CLIMATE CHANGE ADAPTATION GUIDELINES FOR ...old.cwc.gov.in/CPDAC-Website/Training/ToT_reference...(New Zealand) for the Global Environment Facility and Asian Development Bank, 180

ADB-IND TA 8652: Climate Resilient Coastal Protection and Management Project (CRCPMP)

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T

ADB TA 8652: CLIMATE RESILIENT COASTAL

PROTECTCTION AND MANAGEMENT PROJECT

TRAINING OF TRAINERS

IN THE USE OF

CLIMATE CHANGE ADAPTATION

GUIDELINES FOR COASTAL PROTECTION

AND MANAGMENT IN INDIA

25-27 JULY 2016

AT NATIONAL WATER ACADEMY, PUNE

SUMMARY DOCUMENT

GLOBAL ENVIRONMENT FACILITY

ASIAN DEVELOPMENT BANK

MINISTRY OF WATER RESOURCES, RIVER DEVELOPMENT AND

GANGA REJUVENATION

CENTRAL WATER COMMISSION

CENTRAL WATER AND POWER RESEARCH STATION, PUNE

FCG-ANZDEC, NEWZEALAND


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CLIMATE CHANGE ADAPTATION GUIDELINES FOR COASTAL

PROTECTION AND MANAGMENT IN INDIA

SUMMARY DOCUMENT

PREFACE

The ADB Technical Assistance (TA) ‗Climate Resilient Coastal Protection and Management Project (CRCPMP)‘ is financed by the Global Environmental Facility (GEF). The Ministry of Water Resources, River Development and Ganga Rejuvenation is executing the project through the consultants FCG ANZDEC, New Zealand. The TA objectives are to strengthen the resilience of the Indian coast, coastal infrastructure and communities to the adverse impacts of climate change through agreed strategies and effective mainstreaming of climate change considerations into coastal protection and management.

The most important deliverable of the Project is to prepare ‗Climate Change Adaptation Guidelines for Coastal Protection and Management‘. Based on the Preliminary Guidelines prepared in early 2016 and the reviews on the same, ‗Draft Guidelines‘ are prepared. These ‗Draft Climate Change Adaptation Guidelines for Coastal Protection and Management‘ with seventeen Appendices covering in detail all aspects of coastal protection and management in a climate change scenario are circulated. As part of the dissemination of the guidelines to the stakeholders for implementation three training programs are proposed under the project. The first one is being organized during 25-27 July 2016 in Pune is to prepare a team of trainers who will conduct the other two trainings during the project and afterwards.

The Experts of the TA Team have prepared the ‗Draft Guidelines‘, which will be improved after the feedback from the trainees, experts and other stakeholders. The Final Guidelines based on the revision of the ‗Draft Guidelines‘ is expected to be ready by the end of 2016.

This SUMMARY DOCUMENT of the ‗Draft Guidelines‘ covers the most important aspects of the Guidelines mainly to contain the training to three days. It has 12 sections and the 12th one is added as a guide to the trainers. CWPRS is contributing two lectures on coastal engineering and they are added as 13 &14 in this document. This document and its content may be used with proper acknowledgement and be referred as:

Black, K.P., Baba, M., Mathew J.,Kurian, N.P., Urich P., Gear R., Stanley D.O. and Bhat N. (2016) ‗Climate Change Adaptation Draft Guidelines for Coastal Protection and Management in India – Summary Document‘ (Eds: Baba M. and Kurian N.P.) prepared by FCG-ANZDEC (New Zealand) for the Global Environment Facility and Asian Development Bank, 180 p.

However, for all practical purposes the users are advised to refer to the detailed ‗DRAFT GUIDELINES‘ issued separately. The latter should be referred as:

Black, K.P., Baba, M., Mathew J.,Kurian, N.P., Urich P., Gear R. and Stanley D.O.(2016) ‗Climate Change Adaptation Draft Guidelines for Coastal Protection and Management in India‘ (Eds: Black K.P., Baba M. and Parsons S.B.), prepared by FCG-ANZDEC (New Zealand) for the Global Environment Facility and Asian Development Bank, 294 p.


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CLIMATE CHANGE ADAPTATION GUIDELINES FOR COASTAL

PROTECTION AND MANAGMENT IN INDIA

SUMMARY DOCUMENT

CONTENTS

1. Coastal Processes………………………………………………………..4

2. Climate Change……………………………………………………………20

3. Climate Change Impacts on Indian Coast…………………………….34

4. Shoreline Management and Existing Guidelines……………………47

5. Climate Change Adaptation Guidelines for Coastal Protection

and Management in India…………………………………………..58

6. Utilizing the Guidelines………………………………………………….75

7. Sand-Based Solutions for Coastal Protection………………………87

8. Structural Solutions for Costal Protection…………………………..105

9. „Coasttool‟ for Planning Coastal Protection………………………….126

10. Environment Impact and Economic Analysis……………………....144

11. Observation and Modelling……………………………………………………..163

12. Training Skills for Master Trainers…………………………………...175

CWPRS Lectures

13. Overview of Coastal Engineering…………..............................187

14 Coastal Erosion and Protection Measures ……………………203


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CRCPMP TRAINERS TRAINING 25-27 JULY 2016

1.COASTAL PROCESSES

1.1 COAST

Coastal zones (Figure 1.1), encompassing the coastal planes and continental shelves, are

regions that exhibit close interaction between the hydrosphere, lithosphere and atmosphere.

The coasts are dynamic systems, undergoing adjustments of form and processes at different

time and space scales in response to oceanographic and geomorphologic factors. It is

continuously under threat from different hazards including storm surges, flooding, erosion,

sea level rise. It consists of nearshore zone, gulfs, bays, inlets, creeks, tidal deltas,lagoons,

coastal lakes, estuaries, coral reefs, shoals, tidal flats, mudflats, beaches, sand ridges,

coastal dunes, mangroves, marshes, salt-affected land, rocks, cliffs, etc.The developments

attained through over-exploitation of the resources of the coastal zone at the cost of the

environmental quality would inadvertently destabilize the delicate balance between the

biological, geological and meteorological component of the system.

Figure 1.1 A schematic diagram showing the different zones of the coast (after SPM, 1984)

1.1.1 Coastal Evolution

While the hydrodynamic forces are controlling changes in coastal form and evolution, changes in the relative level of the land and the water body, on a variety of time scales, can greatly influence the effect of these processes and the way in which coastal evolution occurs. Dynamic changes in sea level on the order of hours to a few decades reflectresponse of the water surface to meteorologicaland oceanographic processes as well as tidesand can be thought of as periodic or episodicdeviations about mean sea level. They affect thelevel at which wave action occurs and may alsolead to horizontal movements of


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water in tidaland other currents. They thus have an effect oncoastal erosion, transportation and deposition.

In addition to tides produced by the gravitationalforce of the moon and the sun, short-term fluctuationin sea level occur as a result of stormsurge, seasonal variations in pressure and windpatterns and changes in weather patterns on ascale of years to decades such as the El NinoSouthern Oscillation (ENSO) cycle in the Pacific.These fluctuations are also extremely significantecologically, both directly through exposure andcoverage of the intertidal zone and indirectlybecause of the movements of water and nutrientsassociated with the water level fluctuations.

Changes in the relative position of the land andsea on a time scale of thousands to millions ofyears lead to inundation (transgression) or exposure(regression) of the land. Eustatic changes result from changes in the volume of water in theocean basins with the most significant of thesebeing the effects of ice sheet growth and decayduring the Pleistocene. During the last glacialperiod sea level reached its lowest point around25 000 BP at an elevation of about 130mbelow thepresent level. The succeeding Holocene transgressionproduced a rapid rise in sea level to somethingclose to its present level about 5000 BP. Isostaticloading and unloading due to the growth anddecay of the ice sheets complicates the responseof the coast in mid- and high latitudes. Over longertime periods tectonic forces lead to relativechanges in the elevation of the coast locally andto changes in the ocean basins as a result of continentaldrift.

One consequence of human-induced globalwarming is the potential for increased melting ofglaciers and snow fields, particularly in Greenlandand Antarctica where the largest reservoirs offresh water are located. This in turn is leading toan increase in the eustatic sea level worldwide,though locally the magnitude will vary becauseof other factors.

1.1.2 Coastal Processes

Coastal processes can be defined as the set of mechanisms that operate along a coastline, bringing about various combinations of erosion and deposition that in turn influence the geomorphic form and evolution of the coast. The coastal zone is constantly under the action of hydrodynamic processes such as waves, wind, tide and currents. Because of this the land water interface along the coastline is always in a highly dynamic state and nature works towards maintaining an equilibrium condition. Dissipation of energy (due to the hydrodynamic processes) is often provided by the beaches, mudflats, marshes and mangroves.

Coastal processes are very complex and they are not easily predictable as they depend on so many factors that influence the coast like external forces acting like wind, waves, tides, currents etc. and the reason that these factors are mostly site specific makes it all the more difficult. Human interference like construction activities for shore protection which includes both hard and soft measures and also other activities related to port and harbour developments, tourism etc. often makes the otherwise stable system unstable leading to sediment transport which ultimately ends up in either excessive erosion or accretion at some locations.

1.2 COASTAL HYDRODYNAMICS

1.2.1 How are Waves Created?

When wind blows across the sea surface, the friction between the air and water initiates a series of small ripples. These bumps on the sea give the wind something to push against,


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and soon the ripples grow into waves. The waves grow higher, longer and faster, reaching their maximum size when they nearly match the speed of the wind.

The longer and further the wind blows, the bigger and faster the ‗sea waves‘ become. The largest waves on Earth form where strong winds blow steadily across miles of open sea, like the long empty stretch between Antarctica and the Indian Ocean.

In deep water, a group of wind-driven waves, called a wave train, develops into a series of harmonious, rounded ‗swells‘. The train keeps moving even as it leaves behind the wind that formed it. In the open sea, wave trains soon encounter other sets of waves traveling in different directions and with different speeds, heights, and wavelengths. Interference between wave trains can produce a confused, highly irregular sea.

In the open ocean, individual water molecules move in circles as a wave passes. Energy is only thing that waves transmit across the sea.

The highest surface part of a wave is called the crest, and the lowest part is the trough

(Figure 1.2). The vertical distance between the crest and the trough is the wave height. The

horizontal distance between two adjacent crests or troughs is known as the wavelength. The

time taken for a wave to travel one wavelength is called the period.

Figure 1.2 Definition sketch of a propagating ocean surface wave

Long period waves move faster than short period waves. As the storm swell moves across the oceans, the long waves move ahead of the stragglers. Swells also form into groups of larger waves or ―sets‖. We see these large wave sets (also called ‗wave groups‘)arriving at beaches every 5-10 minutes.

1.2.2 How are Waves Transformed in the Shallow Waters?

When waves move into shallow water they start to ―feel the bottom‖—the deepest circling water molecules come in contact with the seafloor. The wavelength decreases and the waves in the train start to bunch up. The wave length (L) is related to the depth of water (h) and wave period (Tp) by

(

)or √

(1)

L0 is the deep water wave length

(2)


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where, g is the acceleration due to gravity. From this equation, the wave length corresponding to the wave period in the given depth of water can be worked out by iteration.

In MKS units, the deep water wave length (Lo) is given by

Lo = 1.56 T2 (3)

The waves are classified as deep water or shallow water waves according to relative depth (d/L) as follows:

1/2 <d/L deep water waves

1/20 <d/L< 1/2 intermediate

d/L< 1/20 shallow water waves (4)

In deep water, the trajectories of water particles are circular and effect of waves does not reach the bed whereas in shallow water, the trajectories are elliptical in nature and the effect due to waves is felt at the bed (Figure 1.3).

Shallow Water Intermediate Water Deep Water

Figure 1.3 Water Particle Trajectories in Progressive Water Waves

If a wave is coming toward land at an angle, or the shoreline is uneven, some parts of a wave will feel bottom before other parts and slow down first. This causes the wave to bend, or refract, so that waves turn toward the shore or wrap around islands or headlands(Figure 1.4).


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Figure1.4Waverefraction: convergence and divergence

The wave begins to lean forward as the crest rushes ahead of the base and eventually the wave topples over and breaks.

1.2.3 What is the Difference Between Wave Setup and Wave Runup?

Within the nearshore zone, the mean sea surface in the presence of waves is usually displaced from the still water level. This variation occurs in response to the onshore momentum flux. Thissuper elevation of water surface over normal still water level due to onshore mass transport of the water by wave action alone is called as wave setup. The setup in the nearshore zone is accompanied by lowering of still water level immediately offshore of the breaker zone and this drop in mean water surface is called as setdown.

The swash zone is the section of the nearshore zone where waves can be seen to directly interact with the shore. It can be defined as the region where the beach face is alternatively covered by the wave uprush, and is exposed by the wave backwash. Wave run up,also known as ―wave uprush‖,is defined as the maximum height above the still water level reached by the wave swash, and it therefore includes the wave setup. This is typically about 15% of the breaking wave height, but it does depend on a number of factors including: the type of breaking wave, the beach slope and the sediment texture.

1.2.4 Where do waves in India come from?

Waves reaching India come from two different sources. The first source is the Southern Ocean where big storms occur(Figure 1.5). The waves travel thousands of kilometres to reach the Indian shore. They arrive in India with directions from the southerly quarter. These waves normally have long periods.

The second major source is the monsoon storms. These storms are close to the Indian shore and produce ―messy‖ seas with short period and irregular waves. On the east coast, the monsoon waves come from north of east. On the west coast, they come from the north of west.


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India is tropical with two main seasons. The non-monsoon season has offshore winds and waves come as swell from the south. During the monsoon season the coasts are impacted by the sea waves. Thus, the Indian coast is sensitive to the waves generated by both the southern oceans and those generated by the monsoons. To understand the effect of climate change on the Indian coast we have to study both the systems and their influence. The wave direction is important in the refraction and diffraction of the waves and along the Indian coast it is normally different by up to 45o between the monsoon and non-monsoon periods.Other waves come from cyclones, especially on the east coast when cyclones travel across northern India in the Bay of Bengal(Figure 1.5).

Figure 1.5Indian Ocean and Southern Ocean Wave Height;Arrows indicate the direction of wave propagation

(source: www.surfline.com/surfdata/chart_viewer/?chart=iowave&id=2950)

Southern Ocean

Indian Ocean

http://www.surfline.com/surfdata/chart_viewer/?chart=iowave&id=2950


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1.2.5 Is there a Wave-Induced Nearshore Circulation?

A circulation system is generated in the nearshore by the breaking waves. Shepard and Inman (1950) introduced the term ―nearshore currents‖ to distinguish the nearshore current system from the other currents. Thus nearshore currents are defined as currents associated directly with waves (Horikawa, 1988), and as such they are confined to the nearshore zone. Nearshore currents include longshore currents, shoreward directed currents and rip currents.This system of circulation that recirculates water in the nearshore is also termed as cell circulation (Komar, 1976). Other currents that may be found in the nearshore zone are known as coastal currents, and they are not generated by gravity waves. Coastal currents include ocean currents, tidal currents and wind-induced currents.

Longshore currents:The nearshore current in the surf zone moving essentially parallel to the shore, is called as longshore currents. They are usually generated by the longshore component of motion in waves that obliquely approach the shoreline. Longshore currents may also be generated by the longshore variation in wave heights that causes a longshore variation in wave setup. This results in a pressure gradient from regions with high waves to regions with low waves. Water can flow along this pressure gradient as a longshore current, before turning and moving offshore as rip current.

Rip currents:A rip current is a strong, narrow seaward directed current perpendicular to the shorelineand are caused by water moving downslope (away from beach) as a result of wave setup. Rip currents are fed by a system of longshore currents. Rip currents tend to form at a spacing of about four times the width of the surf zone.

1.2.6 How are tides generated?

Tides, which are typically observed along most of the coast around the world are, the periodic in nature with occurrence of high and low waters once (diurnal) or twice a day (semi-diurnal), the latter is seen in India. Tides are created by the pull of the Sun and Moon on the oceans. There are many constituents due to variations in the orbits. Global bathymetry plays a very important role as the tidal waves interact with the continents causing interference patterns that can create very small tides in some locations and very large tides in others. The tides on the coast of India increase substantially to the north.

Tides are responsible for moving large amounts of sediments perpendicular to the coast and tidal range governs the width of the littoral zone. Tides influence the distribution and morphology of tidal flats, coastal deltas, Barrier Island, spits etc. It is also responsible for salt and fresh water mixing in estuary and may play an important role in the mixing of ocean currents.

The flow of water (tidal flow) from land towards sea is from high tide to low tide and is called ebb tide, while landward tidal flow from low to high tide is called flood tide. Time of no flow between ebb and flood tide is called slack water (period). If we observe the tide for a longer period, then we observe that the tidal range varies with time. There are periods with large tidal ranges and periods with small tidal ranges. The period with large tidal range is called the spring tide while the period with smaller tidal ranges is called the neap tide. The time between two periods of spring tides is about 15 days.

1.2.7 How are coastal currents generated?

A current that flows roughly parallel to the coast outside the surf zone is called as coastal current. It comprises of wind driven currents, continental shelf currents, tidal currents and currents due to coastal trapped waves. Tidal currents are already dealt in Section B6.


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When wind blows over a water surface, pure wind driven currents are generated by the transfer of momentum from wind to water at the air-sea interface and by friction between moving layers within the water. The direct effect of wind stress is confined to the layer beneath the surface called Ekman layer. The wind-driven currents do not move directly downwind of prevailing wind but is controlled by the Coriolis effect, stratification of the ocean and ocean basin boundaries. Longshore winds are the most important for beaches as they can drive currents up or down the coast which, in the presence of waves, exacerbates the longshore transport.

Inside the harbours and estuaries, the currents are mostly caused by tides or river flows. In combination, these act to form sand bars and help to flush sands from the rivers into the sea. Mangroves create friction on the banks of an estuary which reduces the currents. They commonly collect muds which can eventually lead to natural reclamation of the estuary as the muds build up above the high tide line.

1.2.8 How do Cyclones andStorm Surge occur?

A cyclone is a large scale air mass that rotates around a strong centre of low pressure. Itis usually characterized by inward spiralling winds that rotate counter clockwise in the northern hemisphere and clockwise in the southern hemisphere. The largest low-pressure systems

are polar vortices and extratropical cyclones of the largest scale (synoptic scale). Warm-core

cyclones such as tropical cyclones and subtropical cyclones also lie within the synoptic

scale. Mesocyclones, tornadoes and dust devils lie within the smaller mesoscale. A cyclone's

track is guided over the course of its 2 to 6 day life cycle by the steering flow of the

subtropical jet stream.Tropical cyclones are also called as hurricanes.

Storm surge is an abnormal rise of water generated by a storm, over and above the predicted astronomical tide. It‘s the change in the water level that is due to the presence of the storm. Since storm surge is a difference between water levels, it does not have a reference level.

Storm tide is the water level rise during a storm due to the combination of storm surge and the astronomical tide. Since storm tide is the combination of surge and tide, it does require a reference level.

Storm surge is caused primarily by the strong winds in a hurricane or tropical storm. The low pressure of the storm has minimal contribution! The wind circulation around the eye of a hurricane blows on the ocean surface and produces a vertical circulation in the ocean. In deep water, there is nothing to disturb this circulation and there is very little indication of storm surge. Once the hurricane reaches shallower waters near the coast, the vertical circulation in the ocean becomes disrupted by the ocean bottom. The water can no longer go down, so it has nowhere else to go but up and inland.

1.2.9 How does TsunamiBecome Very Destructive in Shallow Waters?

Tsunami waves are the largest and most energetic on Earth. Tsunami waves are barely noticeable in the open sea – their height is just 1 m or less, and successive wave crests are miles apart. These waves travel very fast, racing across an ocean at the speed of a jet.

Tsunamis are caused by geological events that push a mass of water. Underwater landslides, volcanic eruptions, even asteroids falling into the sea from space, can create a tsunami. But most are caused by earthquakes which move a large piece of seafloor up or down. The displaced water rushes away from the disturbance in waves that spread in all directions.

https://en.wikipedia.org/wiki/Spiral

https://en.wikipedia.org/wiki/Wind

https://en.wikipedia.org/wiki/Northern_Hemisphere

https://en.wikipedia.org/wiki/Northern_Hemisphere

https://en.wikipedia.org/wiki/Clockwise

https://en.wikipedia.org/wiki/Polar_vortex

https://en.wikipedia.org/wiki/Extratropical_cyclone

https://en.wikipedia.org/wiki/Synoptic_scale

https://en.wikipedia.org/wiki/Tropical_cyclone

https://en.wikipedia.org/wiki/Subtropical_cyclone

https://en.wikipedia.org/wiki/Mesocyclone

https://en.wikipedia.org/wiki/Tornado

https://en.wikipedia.org/wiki/Dust_devil

https://en.wikipedia.org/wiki/Mesoscale_meteorology

https://en.wikipedia.org/wiki/Jet_stream


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When tsunamis reach the coast, they behave like normal breaking wind waves. But when all of that enormous energy is compressed into shallow water, the wave grows to massive heights, as much as 40 m or more.

As the wave rises, water is sucked into the crest from ahead of the wave, and shoreline can become suddenly exposed, like an exceptional low tide. The tsunami breaks with enormous force and the water from the collapsed wave can sweep far inland. A tsunami is usually a series of waves which arrive over several minutes to almost 2 hours.

1.3 COASTAL SEDIMENTS

1.3.1 What are the Sources of Coastal Sediments?

Coastal sediments are derived from a wide variety of sources, hinterland rock, rivers, glaciers, volcanoes, coral reefs, sea shells, the Holocene rise in rea level and the cannibalization of ancient coastal deposits. The nature of the source and the type and intensity of the erosional, transportational and depositional processes in a coastal region determine the type of material that constitutes a coast. Beach sediments on most beaches range from fine sands to cobbles. The sizeand character of sediments and the slope of the beach are related to theforces to which the beach is exposed and the type of material available on thecoast. Much of the beach material originates many miles inland where weatheringof the mountains produces small rock fragments that are supplied to thebeach by streams and rivers. When these fragments reach the shore as sand,they are moved alongshore by waves and currents. This longshore transport isa constant process, and great volumes may be transported. Beach material isalso derived from erosion of the coastal formations caused by waves and currentsand, in some cases, by onshore movement of sediment from deeper water.In some regions, a sizable fraction of the beach material is composed ofmarine shell fragments, coral reef fragments, or volcanic materials.

1.3.2 How are Coastal Sediments Classified?

Coastal sediments can be classified by virtue of their different properties:

(i) Size: One of the most important characteristics of sediment is the size of the particles. The division of sediment sizes into classes such as cobbles, sand, silt, etc., is arbitrary, and many schemes have been proposed. However, two classification systems are in general use today by coastal engineers: Modified Wentworth Classification. The other is the Unified Soils Classification or the ASTM Classification, which various American engineering groups have developed.

(ii) Compositional properties: Coastal sediments can be classified based on its composition viz. minerals, density, strength, etc.

(iii) Fall velocity: Another way to classify sediments is by its fall velocity which has its application in coastal engineering. Fall velocity is a function of sediment size, shape, and density as well as the fluid density, viscosity and several other parameters.

(iv) Bulk properties: Porosity, bulk density, and permeability are related bulk properties that arise from the fact that aggregations of sediments have void spaces around each grain.

1.3.3 Cross-shore and Longshore Sediment Transport

Depending on the direction of transport, sediment transport can be classified into two: Longshore transport and cross-shore transport. Longshore transport in the surf zone is caused by longshore currents generated by waves as described in Section B5. Tidal and


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wind generated currents cause alongshore transport in the innershelf. Gradients in the longshore transport rate alter the shoreline, resulting in areas of erosion and accretion. The gradients and their characteristic scale determine the spatial extent of these areas. The mechanisms causing the gradients in local transport are described in the next section.

Cross-shore sediment transport encompasses offshore transport that occurs during storm or rough weather conditions and onshore transport which dominate during fair weather period. Net cross-shore exchange of sediment may occur over long time periods and large areas, having implications for regional shoreline evolution. During a typical year the net cross-shore transport at the boundaries of the nearshore zone may be small, bur over decades or centuries the net contribution could be significant. Also, in the case of extreme events, alarge net transport could take place over ashort time period, having implications forthe evolution of the nearshore topography at much longer time scales than the storm itself.

1.4 BEACH MORPHODYNAMICS

1.4.1 What are the Factors Causing Beach Morphological Changes

The processes affecting beach morphological changes (or erosion/accretion) can be broadly classified into (i) natural and (ii) man-made factors.

Natural factors:

The natural factors affecting beach morphological changes are:

(i) Waves (ii) Wave-induced currents (iii) Coastal currents including tidal currents (iv) River/Estuary inputs (v) Geomorphological factors such as headland, cliff, bay etc. (vi) Coastal hazards such as storm surge, sea level rise, etc.

Human-induced factors:

Human-induced activities can cause morphological changes. They include: (i) Coastal structures (ii) Beach sand mining (iii) Reduction in sediment supply to the coast due to dredging, river sand mining,

damming, etc.

Morphological changes (erosion/accretion) can be both short-term and long-term depending

on the time scale. Seasonal (short-term) erosion occurs during the monsoon or episodic

events. This eroded beach is normally rebuilt during the fair weather period resulting in no

net erosion or accretion over a period of one year. However, in some sectors of the coastline

net erosion or accretion occurs on a longer time scale, mostly due to human interventions.

1.4.2 What is a Sediment cell?

A sediment cell (also known as littoral cell) is defined as a length of coastline which is relatively self-contained. Common examples are beaches between large headlands (Figure 1.6). The volume of sand is essentially fixed, notwithstanding new deliveries from rivers.

Many scientists assume that works within a sediment cell will have no measurable influence on locations outside the cell. Thus, the sediment cell is a convenient method to sub-divide the coast into zones which are essentially independent with no sediment exchanges between the cells.


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Figure 1.6 Definition sketch of littoral cell.

The sediment cells can be broadly divided into Primary, secondary and tertiary. The primary cells can be based on coastal geomorphology, sources of sediments, stores of sediments, interface of rocky-sandy-muddy coast and other major features which divide the coast.

The secondary cells can be demarcated by changes in littoral front, change in coastal alignment, decadal erosion / accretion, man-made littoral barriers, tidal inlets / river mouths, delta front and such sediment binding features. The tertiary cells are actually management units decided based on land use and other coastal activities which affect the sediment movement up and down the coast.

1.4.3 What is Sediment Pie?

The ―sediment pie‖ is the total volume of sand available on a beach. The pie is the volume in a cell. In the cell, there‘s a fixed total volume of sand available for a beach i.e. the volume currently on the beach plus any sand brought to the beach by waves and currents or a river(Figure 1.7). Much of the sand on global beaches came to the shore several thousand years ago (during the Holocene period). Supply from offshore is small now. Legal and illegal sand mining on the beaches is causing a major reduction. Large dams on many rivers have blocked deliveries to the coast. People are encroaching on the beach with buildings and other infrastructure, which buries a large volume of sand and disturbs the coastal processes.

Thus, the sediment pie is getting smaller. The sediment pie rules are:

Sand is precious

There is a limited volume of sand available

If one coastal structure captures sand, then less sand will go to the downstream locations

Dredging of sand to be sold or put to reclamation reduces the volume in the pie

Not much new sand is coming to the beaches

Changing the natural beach processes that nature put in place when the earth was formed is an error

Longshore Transport


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Table 1.1 Types of coastlines of different maritime states of India

In the longshore direction, beaches are connected along their full length. They are very

responsive to the local wave climate. Longshore currents link each part of the beach and

carry sand along the shore. As the season changes, the longshore currents in India

usually change in synchrony with the wave climate. Net movement is to the north in the

dry season and to the south in the monsoons. Of course, there are exceptions for

beaches which might be sheltered by headlands or have unusual orientations.

Figure 1.7 Sediment transport pathways


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1.4.4 Stable (“Happy”) Beach

A stable beach has a neutral alignment relative to the wave climate. Waves come from many directions and they push sand along the shore. But if the total push one way is equal to the total push the other way, then the beach has neutral sediment movement, i.e. Happybeaches are much less likely to be subject to erosion, unless the sand is trapped by structures or removed by human activities. Commonly such beaches reside between natural headlands or on beaches with orientations that are perpendicular to the average wave power reaching the beach.

1.4.5 Unstable (“Hungry”) Beach

A Hungry beach is out of alignment with the waves. When waves come from many different directions the sand moves up and down the coast. But the hungry beach has more sand going one way than the other. This means that the net sediment movement along the shore is up or down the coast.

To be stable, Hungry beaches need a constant sediment supply or they need food. The food has traditionally come from large rivers and we still see evidence of large river deltas bulging out from the shore in India. The hungry beach is out of balance if the sand supply is reduced (e.g. dams on rivers, sand mining or large structures which obstruct their supply). Sand can be quickly washed away from a hungry beach, if the sand inputs are less than the outputs along a section of shoreline.

1.4.6 Beach evolution cross-shore: the “dune-bar connection”

In the cross-shore direction, beaches are like the tip of the iceberg. Much of the beach is underwater, beyond the sand we love to enjoy. There are several key morphological features: sand dune, upper platform, beach face, subtidal beach, bar, and offshore zone.

Nature has evolved a simple system to keep beaches stable:

Step 1: When big storms arrive (mostly during the monsoons in India) the waves cut into the berm and carry the sand offshore to the underwater sand bar where waves are breaking

Step 2. The sand bar gets higher. This causes the breaking waves to lose more energy when breaking which reduces the wave height at the shore

Step 3. Eventually when the sand bar is very shallow, the erosion of the beach face and berm stops

Step 4. The sand on the bar is not lost. During calm conditions under clean (longer period) swells, the sand is moved slowly back to the berm and winds or waves under very high sea levels can move the sediment to the sand dune

Step 5. The sand lost from the berm and dune during the storm is now back again.

1.4.7 Over-topping

Over-topping is a natural part of the beach system. Big waves can set-up the water level and the swash of the broken wave on the beach face goes over the top of the berm. Over-topping helps to build-up the berm and sand dune. When waves over-top they bring sand shorewards which builds up the beach.

People living in this zone are not fond of this natural process as the over-topping can lead to minor flooding in their houses. But the beach is actually behaving naturally by using this simple process to re-build the beach and berm. Rock seawalls, for example, interrupt overtopping and the beach is normally lost.


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Under climate change with higher water levels this highly important over-topping process will act to make the beaches higher and will protect the villages behind. But people need to allow this process to occur. We acknowledge that people view this process as flooding.

1.4.8 Coastal works

Sometimes people build their houses on the top of the sand dune. Sometimes governments put roads along the foreshore, buildings on the beach, rock seawalls on the dune, walls across the beach to train rivers and/or build ports which project offshore on an open sandy shoreline. Sometimes, swamps dry up and are reclaimed and river flows are diverted to stop flooding which changes sand delivery to the coast.

All of these affect the sediment supply to downstream zones. Great care is needed. The engineer needs to be aware of the Sediment Cell, Sediment Pie and the state of the beach to ensure that the total volume of sand remains sufficient to sustain the beach.

1.4.9 Design water level

Many factors affect sea levels. Offshore key factors are:

Tides

Large-scale ocean circulation

Oceanic gyres

Coastal currents

Coriolis deflection of currents

Local wind set up

Cyclones

Barometric pressure

Sea level rise due to climate change

Inshore the factors include:

Wave height

Wave period

Wave direction

Surfzone width

Beach gradient

Sand grain size

Sand bars

Surfzone set-up

Surf beat

Swash and run-up

Surf zone currents

Rainfall

These parameters and factors determine the level of the sea at the coast, and the ultimate

re-sculpting or retreat of the coast in response to waves and storms.

1.5 COASTAL PROCESSES IN THE CLIMATE CHANGE SCENARIO

1.5.1 Climate change and extreme events

Many studies (e.g. IPCC 2013) have shown that climate change may lead to changes in the frequency and intensity of the meteorological drivers of sea level change and to riverine flooding. According to a more recent study by Knutson et al (2010), it is likely that the global frequency of tropical cyclones will either decrease or remain essentially unchanged under


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climate change, however, regional and local frequencies could still change substantially due to other meteorological influences such as ENSO.

While projections of tropical cyclones in the north Indian Ocean region are uncertain, the available studies suggest that there may be an increase in the number of tropical cyclones in the more intense categories. Clearly, any increase in the magnitude of cyclones will make shorelines more susceptible to modification by waves and storm surges as well as pose a large risk to cities and coastal communities. There are several incidents in India in the past, tropical cyclones can generate heavy rainfall, very strong winds and big storm surges when they make landfall, leading to considerable damage to coastal environments and built assets (e.g. 1999 Odisha Cyclone).

Figure 1.8 Cumulative track map of all North Indian ocean cyclones from 1970 to 2005

(source : https://en.wikipedia.org/wiki/North_Indian_Ocean_tropical_cyclone)

1.5.2 Beach responses

Beaches have been in existence for millions of years, and so they have intrinsic stability. But will they survive climate change? And what factors may prevent them from surviving, particularly human interventions that may disrupt natural systems. Beaches can simply change their alignment to re-distribute sand into different locations. Or they may work to build up the sand dune. Alternatively, they may simply erode as sand supply dwindles or moves elsewhere.

The problem of beach adjustment under climate change is complex and subtle. A stormier or altered wave climate with higher water levels defines the real impact of climate change on the coast.

Some of the questions related to coastal processes in the climate change scenario is answered in the following sections.

1.5.3 What if storms get stronger and more frequent?

The ―Dune-Bar Connection‖ relies on storms to take sand to the bar while clean swell during calm conditions brings the sand back to the dune. If storms get stronger and more frequent and the balance between offshore and onshore sand migration is changed, then the beach will erode.

1.5.4 What if the monsoon gets longer/shorter or weaker/more intense?


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The average orientation of beaches in India depends on both the monsoon and the non-monsoon wave conditions. Any shift in the ratio of the duration, orientation or intensity of the monsoon (relative to the non-monsoon) will have big impacts. On long beaches, rotation can lead to hundreds of metres of accretion at one end and the same amount of erosion at the other end.

1.5.5 What if the wave period changes?

Wave periods are mostly shorter in the monsoon. Wave period is a key factor determining if net sand movement is onshore (long wave periods) or offshore (short wave periods). A shift in the period could have dire consequences.

1.5.6 What if sand supply changes?

Locations experiencing drought under climate change will have smaller flows in the rivers. This will lead to a corresponding reduction in sand supply to the coast. Wetter zones might have improved supply, but floods need to be accommodated. Continued sand mining will have dire consequences.

1.5.7 What if humans build rock walls along the entire coast?

Case studies show that while the rock seawalls prevent shoreline retreat, the erosion continues underwater. Rock walls along the coast would fundamentally change the beach system and lead to further beach erosion.Rock walls are unsuitable for coastal protection under increased water levels due to Climate Change.

1.5.8 What if cyclones move further south?

Most beaches are close to equilibrium with their environment. But a sudden shift in the location of cyclone landfall puts the beaches out of alignment with their environment. Such dramatic shifts would be one of the most important impacts, particularly along the east coast of India around the Chennai district and further north.

REFERENCES

Horikawa, K., 1988. Nearshore Dynamics and Coastal Processes: Theory, Measurement and Predictive Models, University of Tokyo press, Tokyo, 522p.

IPCC, 2013. Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1535 pp.

Kalsi, S.R. 2006.Orissa super cyclone – A Synopsis.Mausam, 57, 1 (January 2006), 1-20

Komar, P.D., 1976. Beach Processes and Sedimentation, Prentice-Hall Inc., Englewood Cliffs, New Jersey, 429p.

Knutson, T.R., McBride, J.L., Chan, J., Emanuel, K., Holland, G., Landsea, C., Held, I., Kossin, J.P., Srivastava, A.K. and Sugi, M., 2010, ―Tropical cyclones and climate change‖, Nature Geoscience, vol. 3 (3), pp. 157–163.

Shepard, F. P. and Inman, D. L. 1950. Nearshore water circulation related to bottom topography and waverefraction. Transactions of the American GeophysicalUnion, 31, 196_212.

SPM (Shore Protection Manual), 1984. U.S Army Coastal Engineering Research Centre, U.S. Govt. Press, Washington, D.C.


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2.0 CLIMATE CHANGE

2.1 THE SCIENCE

Carbon dioxide is essential to life on Earth. Without carbon dioxide, the Earth would have been over thirty degrees Celsius colder, and not been habitable for humans. It is the presence of carbon dioxide naturally in the atmosphere that maintained temperatures which helped the growth of agriculture and the spread of human civilizations. But in 2013, for example, humans were responsible for adding 34 billion tonnes (1 tonne = 1,000 kgs) of carbon dioxide from burning fossil fuels and two billion from cement production Another four billion tonnes‘ carbon dioxide got added by our cutting forests; when wood burns or rots, it emits CO2. The contribution of the other greenhouse gases is calculated as an equivalent of CO2 in their capacity to cause warming. So, methane‘s share is nine billion tonnes of CO2-equivalent, and nitrous-oxide and other gases, four billion tonnes. To repeat this simply, CO2 share from burning fossil fuels is 34 billion tonnes, from all activity is 40 billion tonnes, and other gases are equal to another 13 billion tonnes, for a single year‘s (2013) total of 53 billion tonnes of CO2-equivalent.

A quarter of the carbon dioxide gets absorbed by the oceans, making them more acidic. Trees, soil, grass and root systems absorb about the same amount on land. A little under half remains in the atmosphere. Every 1 ppm increase in global CO2 is equivalent to emissions of roughly every eight billion tonnes of carbondioxide in the atmosphere. In 2015, CO2 levels in the atmosphere crossed 400 ppm for the first time in thelast four million years. It was at about 280 ppm around the start of the Industrial Revolution (18th century).

CO2, methane and nitrous oxide trap some of the Sun‘s invisible heat radiation coming up off the Earth, hence causing global warming. Over ninety per cent of the excess heat goes into the oceans. They have a considerable absorption capacity. Warmer oceans disrupt/alter hydrological/rainfall cycles like more intense cyclones and sea level rise from thermal expansion. More heat also melts glaciers and warms soils leading to more biological activity and for permafrost areas the potential for the release of considerable sinks of methane.

Between 1961 and 1990, India used to be 24.87 degrees Celsius, as an average of all seasonsduring those years. By 2001-2010, the average had risen to 25.51 degrees C. The world has become one degree Celsius warmer since the 18th century. The Earth‘s average used to be little over 13.5 degrees C and is now 14.5 degrees C.

The Arctic, North Africa, southern Europe and the Himalayasare warming faster than everywhereelse.There is an important lag time between greenhouse gas emission and rise in temperature. Inertia in the system means that even if we stopped all greenhouse gas emissions now we could experience a further 0.6 degrees Celsius of warming, likely above the current 1 degree rise.

Climate change is a changein weather patterns, rainfall, storms, droughts, over time. It is the most important consequence of globalwarming but not the only one. Global warming also leads to ice glacier melt in Antarctica and warms ocean waters and can cause soils to be drier. There are two broad scale human responses to these changes in our environment in the context of climate change:

• adaptation – actions to address unavoidable climate change, to minimise risk and disruptions, and to strengthen resilience and preparedness, and


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• mitigation – actions to reduce GHG emissions and to modify actions, aiming to reduce the likelihood of further change which may have more severe, more damaging and more costly impacts.

Figure 2.1: The overlapping nature of climate change adaptation, disaster risk reduction and

sustainable development require coordinated actions across the three realms.

These two broad concepts along with disaster risk reduction should be intertwined as actions taken (adaptation) to improve resilience to a changing climate should as much as possible reduce the further emission of greenhouse gases (mitigation) that will only exacerbate the problem.

2.2 THE FUTURE

The Fifth Assessment report (AR5) of the United Nations (UN) Intergovernmental Panel on Climate Change (IPCC) was released in four parts between September 2013 and November 2014 and supersedes the 2007 Fourth Assessment Report (AR4) as the most comprehensive review of climate science and policy. AR5 contains more extensive information on climate change‘s socio-economic impacts, and hence its role in sustainable development. The features include a new set of scenarios that are applied across the three working groups:

Working Group I ―The Physical Science Basis‖

Working Group II ―Impacts, Adaptation and Vulnerability‖

Working Group III ―Mitigation of Climate Change‖

Additional activities include a Task Force on Greenhouse Gas Inventories, a Synthesis Report that integrates science from the three working group reports, and special reports issued through AR5 and previous assessment cycles.

2.2.1 Differences Between Modelling Periods

Climate modelling through General Circulation Models (GCMs), also known as Global Climate Models, has been a substantial part of the Assessment process since 1990. The number of modelling groups producing GCMs has increased markedly over successive Assessments, starting with five groups generating eight models for the FAR (1990) to 27 groups producing 61 models for AR5.

These models represent the natural (physical, chemical and biological) processes of the atmosphere, ocean, cryosphere and land surface, and are the most sophisticated available for simulating increased GHG concentrations on the global climate system. Over time there has also been an expansion in modelled variables, including both the marine and


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atmospheric environment. For AR5, many models have daily varying temperatures (with minimum, mean and maximum values) so that change patterns can be extracted for the first time; AR4 models did not contain this information. Only 12 AR4 GCMs produced daily precipitation outputs; with AR5 more daily outputs results in better modelling of extreme rainfall events. Previously, a location‘s monthly rainfall could show a drying signal even though individual extreme rainfall events increased in intensity, and few groups had managed to develop methods for working with such limited daily GCM data.

More than 20 models (of the current 61) have all the necessary data for post-processing and incorporation into extreme rainfall event models for risk assessments, and 40 models can generate spatial scenarios. This considerable data enrichment adds additional information for any set of tools applied to real world problems, and improves the statistical significance of results. The IPCC is still advising that an ensemble or mean of a group of models be applied when using GCM model data (Stocker et al., 2010).

Global scenario parametersare also necessary to generate climate outputs. Prior to AR5 this information was communicated through the storylines of emissions scenarios (Special Report on Emission Scenarios [SRES]); prior to that FAR was driven by analogue and equilibrium scenarios for impact assessment that included business as usual (as well as policy) scenarios. Forty SRES scenarios represented different assumptions on pollution, land use change and other driving forces of climate change. This scenario list was refined to six families for application in risk assessments with the descriptors A1FI, A1B, A1T, A2, B1 and B2. In 2005, the process moved away SRES with development of representative concentration pathways (RCPs) introduced at an IPCC Expert Meeting on Emissions Scenarios, followed by IPCC workshops (2005, 2007). For the first time the RCPs include scenarios that explore approaches to climate change mitigation in addition to traditional ‗no climate policy‘ scenarios.

Each RCP represents a different emission pathway:

RCP8.5 - leads to a greater than 1370 PPM (parts per million) CO2 equivalent by 2100 with a continued rise post-2100

RCP6.0 - stabilises by 2100 at 850 PPM CO2 equivalent by 2100 without overshoot

RCP4.5 - stabilises by 2100 but at 650 PPM CO2 equivalent without overshoot

RCP2.6 - peaks at 490 PPM CO2 equivalent before 2100 and then declines

The global atmosphere is currently close to 400 PPM CO2 equivalents and concentrations of CO2 and non- CO2 gases are increasing at a rate that is of concern (Prinn 2013). Table 2.1 provides a RCPs overview. Table 2.1: RCPs Overview (van Vuuren et al. 2011; Moss et al. 2010; Rojeli et al. 2012)

Description CO2

Equivalent SRES

Equivalent Publication – IA Model

RCP8.5 Rising radiative forcing pathway leading to 8.5 W/m2 in 2100.

1370 A1FI Raiahiet al. 2007 – MESSAGE

RCP6.0 Stabilisation without overshoot pathway to 6 W/m2 at 2100

850 B2 Fujinoet al.; Hijiokaet al. 2008 – AIM

RCP4.5 Stabilisation without overshoot pathway to 4.5 W/m2 2100

650 B1 Clark et al. 2006; Smith and Wigley 2006; Wise et al. 2009 – GCAM

RCP2.6 Peak in radiative forcing at ~ 3 W/m2 before 2100

490 None van Vuurenet al., 2007; van Vuurenet al. 2006 -


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and decline IMAGE

2.2.2 Extreme Temperatures and Precipitation

In AR4, the IPCC concluded (Solomon et al., 2007) that climate change had begun to affect the frequency, intensity and duration of extreme events (i.e. extreme temperatures, extreme precipitation and floods and droughts), some on which are projected to continue. A subsequent IPCC assessment (a special report on managing risks of extreme events to advance climate change adaptation [SREX]) confirmed these assessments (Seneviratneet al. 2012).

The ability of GCMs to reproduce extremes with different time scales is of great importance. In 1950 the researcher Jennings discovered the relationship between the global maximum of precipitation and duration; since that time his findings have been reinforced by numerous studies. Now the question is ―how do the new models perform and how can their results be folded into decision making?‖

In general, high temperature extremes in the late 20th century are plausibly modelled, with 20 year return values (on a global scale) that are within the range of uncertainty in historical reanalysis data of about 10 C. Local scale discrepancies are greater, with values of up to 50

C, with more extreme differences over the land than the oceans. The uncertainties in low extremes are greater than that of the warm extremes; however, they still fall well within estimates obtained from different reanalysis data.

Precipitation extremes have always been challenging to model. Large uncertainties remain, especially over tropical and subtropical regions, with AR5 models performing similarly to AR4 models. Both perform better in the extratropics where they compare favourably with observational records. By the end of the century, the various RCPs express different possible shifts in precipitation intensity. RCP 2.6 global multi-model results indicate a 6% increase of high extreme daily precipitation while the RCP 4.5 experiment shows a 10% increase and RCP 8.5 20%. Local manifestations of the difference between the various RCP increases can vary considerably and point to the importance of local analysis over the use of global approaches. These changes in extremes are 2 to 3 times greater than the corresponding multi-model change in global annual precipitation. Return periods for extreme precipitation are expected to shorten for much of the world, except in some of the subtropics‘ drying regions. A strong indicative trend is the shortening of 20 year return periods to 14, 11 and 6 years for RCPS 2.6, 4.5 and 8.5 (respectively) by the end of the century, compared with the historical 1986 to 2005 period. Another emerging trend is the increase in intensity of very short term sub-daily events as found in India and around the world (Roy, 2009). The application of new 3 hourly GCM patterns for rainfall show that short duration events could become increasingly intense and become more impactful for both built and natural environments (localised flash flooding and landslips).

In summary, AR5 extremes for temperatures and precipitation are generally in agreement with the AR4 models (Kharinet al. 2013). While annual precipitation may show a decrease for many locations, the intensity of extreme events is likely to increase (Donat, et al., 2016). The expansion in the GCM daily data availability permits the application of ensembles with more members than that in AR4. This means that while statistical analysis of uncertainty across models has improved, it acknowledges that uncertainty in certain regions and locations remains particular high for precipitation (although less so for temperature).


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2.3 AR5 IN INDIA

The IPCC synthesis report focuses on changes in weather patterns and projections related to extreme weather events. These changes are expected to have a cascading effect on ecology, the health of the economy and people.

Net annual temperatures in India in 2030s, with respect to 1970s, could increase from 1.7-2.2°C. Extreme temperatures are expected to increase by 1-4°C. The mean and extreme precipitation during the Indian summer monsoon is expected to increase but monsoon breaks could also increase causing rapid onset drought conditions from time to time (Turner and Annamalai, 2012).The Himalayan region could experience the greatest increase in precipitation, while the north-eastern region could have the lowest increase. More extreme rainfall events are expected but less intense events could result over the central Indian region and in many other areas.

The frequency of cyclones could decrease in 2030s, but with an increase in average cyclone intensity. Floods and droughts are likely to increase in India since there will be a decline in seasonal rainfall, coupled with increase in extreme precipitation during monsoon. Some river basins in India could experience a greater possibility of floods in September but with an increased risk of water scarcity in April.

2.4 SEA LEVEL RISE

Global mean sea level (MSL) rise for 2100 (relative to 1995) for the RCPs is projected in the following 5–95% ranges for AR5:

28-60 cm (RCP2.6)

35–70 cm (RCP4.5)

37–72 cm (RCP6.0)

53-97 cm (RCP8.5)

Confidence in the projected ranges comes from process-based model consistency, in addition to observations and physical understanding. The IPCC notes that there is currently insufficient evidence to evaluate the probability of specific levels above the likely range and this has been affirmed by recent research (Kopp, et al., 2016). It is unlikely that global MSL will exceed the above levels by the end of the century unless there are substantial changes in the Antarctic and Greenland ice sheets. Current research is focused on better understanding the potential for rapid and catastrophic sea level rise over a much shorter timeframe (Krinner and Durand, 2012).

While MSL rise is important, it is also critical to recognise at least two other factors in India:

Sea level rise does not occur evenly across the globe; some areas rise faster than others because of changes in ocean currents, sea water temperatures (the thermal expansion component varies), air pressure and geo-tectonic movements (e.g. land rising can partially or totally offset sea level rise in some localities or subsidence owing to tectonic or other activities such as groundwater extraction can exacerbate local sea level rise).

Extreme sea level events (in addition to sea level rise) often (but not exclusively) arise with the confluence of events such as exceptional seasonal high tides, wind and waves associated with tropical depressions or extra tropical low pressure systems and coastal bathymetry. Extreme sea level (surge) events can have a profound impact on people and property. This can now be modelled for a location, in conjunction with MSL rise, in order to improve understanding of return periods for extreme events and the actual potential sea level during such an event.

Sea level rise on the Indian coast is variable but within a range of between 10 and 20 cms across the entire country with potential rise around the coast of up to 120 cms by 2100. Local variation is important with depth of the water column, vertical land movement and a host of other local factors mean there is subtle local variation in sea level rise.


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2.5 INTENDED NATIONALLY DETERMINED CONTRIBUTIONS (INDCS)

2.5.1 Future rates of change

A pragmatic approach explores the big picture issues rather than diving deeply into individual and nuanced aspects of each and every possibility that could impact change in future greenhouse gas emissions. With the very recent release of Intended Nationally Determined Contributions (INDCs) and potential limitations in societal capacity for achieving not only a reduction in greenhouse gas emissions but a decarbonisation of the world economy stated goals for reducing future temperature rises could be compromised.

2.5.2Is 2 °C the Bottomline?

There is plenty of talk of limiting climate change and global warming to 2 degrees C or less from pre-industrial levels. One of the most influential global groups in the G7 +1 that when they met in June of 2015 made strong statements with regard to the Conference of Parties (hereafter COP) negotiations that were to take place at the end of 2015.

The agreement should enhance transparency and accountability including through binding rules at its core to track progress towards achieving targets, which should promote increased ambition over time. This should enable all countries to follow a low-carbon and resilient development pathway in line with the global goal to hold the increase in global average temperature below 2 °C. (G7 +1 Leaders Summit, emphasis added)

The latest COP 21 negotiations have concluded in Paris. They do relate and are linked by previous COP meetings and one of the strongest linkages is with the Copenhagen meeting (COP 15), where Member States agreed to a goal of limiting climate change to no more than 2° C. At the current COP (21) there was considerable – but not universal – support for supplementing this goal with a long-term decarbonization goal, like that included in the G7+1 Leaders Statement in June 2015 and noted above, to provide a signal to business and investors. Many countries wanted to include a decarbonization goal in the Paris agreement, but as a consensus could not be reached to do so, a possible fall-back would be to include the goal in the Conference of the Parties (COP) decision that adopts the Paris agreement, which would give the goal a slightly lesser political status (Bodansky 2015).

2.5.3 Limiting to 2.0 (or better) Degrees Celsius

One of the more critical pieces of country engagement in the COP process has been the development of Intended Nationally Determined Contributions referring to greenhouse gas trajectories (i.e. reductions but not in all country cases) that include: current policy projections; short-term pledges (up to 2030) and long-term pledges (up to 2050) with no explanation of post-2050 targets or implementation guidelines or clear statements on binding commitments.

As of 7 December 2015, 158 submissions to the UNFCCC, reflecting 185 countries (including the European Union member states), and covering around 94% of global emissions in 2010 (excluding LULUCF) and 97% of global population had been made. A further 3% of global emissions are coming from international aviation and maritime transport. Almost 1% of global emissions are covered by countries that are not Parties to the UNFCCC.


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Various groups have been analysing the INDCs and what they could mean in relation to the achievement of the target global temperature. Given current commitments and on-going negotiations for decarbonising the global economy pledges look likely to fall short of the 2.0 °C target. Even if the global community were to reach the goal of limiting warming to 2.0 °C there would still be up to 30 cms of sea level rise and important shifts in climate and extreme events that must still be considered in adaptation planning (Wigley 2015).

Importantly there are sizable gaps between what is stated in the recently submitted INDCs and what history tells us. This is called the emissions gap and there are some very good reasons why this gap may persist for the foreseeable future and even if current pledges are fully realised will leave global temperatures at around 2.7 °C and perhaps higher depending on compliance and rates of reduction achieved.

Figure 2.2: Global mean temperature increase (and uncertainty range) by 2100 above pre-industrial temperature and INDC pledges versus current policies to 2100 (Source: Jeffery, et al., 2015).

However, the inertia in the energy system and emissions – e.g. the long lifetime of power plants and other fossil fuel powered technology – sets limits for how quickly nations can realistically slow their emission pathways. Highest emission reduction rates found in the mitigation scenario literature are in the order of 4% to 6% per year, importantly such rates have only been achieved over relatively short periods of time and tend to be European countries (van Vuuren and Stehfast, 2013). Also there is a debate if those countries achieving such rates have simply ‗exported‘ production to the developing world where the GHGs for production are emitted and then finished products are imported without accounting for those GHGs. On a longer timeframe of 50 years, the maximal rates of reduction observed in scenarios has been only 3% to 4%.Therefore it seems unlikely that most countries could sustain multiyear reduction rates exceeding 4% in the future (Elkholm and Lindroos, 2015).


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Figure 2.3: Future temperature and emissions gap (Source: Climate Action Tracker Partners

2015).

The 2030 level can affect the achievable future emission levels: being on a higher level initially makes it more difficult to reach a low emission level in the future, as the rate at which emissions can be realistically reduced is limited. The 2030 level can exclude from reaching the target if the further cuts necessary to meet the 2°C target let along 1.5 °C have to be scaled uprapidly. This seems highly unlikely given inertia in the energy system and other emission sources (Elkholm and Lindroos, 2015). Underlying such rates of possible emissions reductions beyond international and binding political agreements are national and local issues of politics, institutional capacity and mandates, regulations and standards not only of the UNFCCC but also International Organisation for Standardisation (ISO) and industry requirements. There are also issues of technological capacity and transfer, financial and development stages and goals and equity gaps and financing limitations.

For example, India alone through its submission of its INDC requires significant external financial support for capacity building, technology development and transfer. They noted a need for USD 834 billion to achieve moderate low carbon development up to 2030. The Green Climate Fund update at COP20 noted a mobilisation of only USD 10.2 billion to date by contributing parties. The target is for USD 100 billion a year by 2020. Even if achievedIndia alone could consume eight of the next ten years of funding to meet its needs.

The Green Climate Fund is one of the most divisive issues at COP 21 and there are long standing disagreements on what has and will constitute donations to the fund. There remains a large gap between the expectations of developing countries for significant levels of climate finance, and donor countries, who already feel donor fatigue. A recent reportfound that $62 billion in climate finance was mobilized in 2014, up from $52 billion in 2013, although these figures are disputed because of the major methodological questions about what should be counted as climate finance (OECD 2015a).


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2.5.4 What is Best Practice?

Given the confluence of needs for a rapid reduction in greenhouse gas emissions, the slow onset of negotiations to effectuate such change, the move toward non-binding agreements on such reductions is the continued adaption of a worst case scenario – RCP 8.5 ensemble of models and medium to high sensitivity approach justifiable? And is it even possible when countries or individual clients are not bound by any international standards or national regulations but are free to choose the level of risk they may wish to carry forward through the applications of one of many possible emission pathways. Is this ethical/defensible given the new Intended Nationally Determined Contributions (INDCs)?

What if we try to estimate future scenarios from INDC commitments . . . theory and practice?

The 158 submissions to date representing 185 countries currently reporting represent about 90 percent of emissions. Clearly there is a greater than 50 percent chance that the global community is not going to make target temperatures and driving emission profiles. Do we therefore advise to plan for a worst case 3.4 °C or 2.7 °C (or 2.2 °C) world for durable 50+ year infrastructure (rather than 4.9 °C +)?

Table 2.2: Mean annual temperatures and changes in °C to 2030 and 2050 from a baseline of 1995 for RCPs 8.5 medium sensitivity. Global mean temperature change to 2030 for RCP

8.5 is 0.94 °C and for 2050 is 1.70°C, both with medium sensitivity (Warrick et al. 2013).

Settlement Baseline (1995) RCP 8.5 (change) to 2030

RCP 8.5 (change) to 2050

Mumbai 26.9 27.7 (0.8) 28.4 (1.5)

Goa 27.1 27.9 (0.8) 28.6 (1.5)

Bengaluru 23.6 24.5 (0.9) 25.2 (1.6)

New Delhi 24.6 25.8 (1.2) 26.7 (2.1)

In India coastal and more southern cities at elevation -- as expected -- show less of an increase in temperature than inland and more northern settlements over time owing to the moderating effect of the sea. Overall when away from the sea India is warming more quickly than the global mean.

In relation to the INDCs that have been submitted there is as shown a general consensus that current pledges will fall short of achieving the 2.0 °C target (and almost certainly the 1.5 °C target suggested by SIDS). Ultimately, can the INDCs and the process be trusted? Monitoring and evaluation is critical and current negotiations are trending toward making it binding to reduce emissions, but actual targets be unbinding (Bodansky, 2015; factorCO2 2015).


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Figure 2.4: The global mean temperature change of the three selected RCP scenarios. The

graph shows that up to 2030, global mean temperature is projected to increase by about

1.0oC (from 1995), irrespective of the RCP scenario and subsequently the future

temperature change projections diverge by 2050 and even more by 2100, depending on the

RCP scenario.

2.6 MAINSTREAMING OF CLIMATE CHANGE ADAPTATION

Action that addresses the interlinked challenges of disaster risk, sustainable development and climate change is a core priority given that 90% of recorded major disasters caused by natural hazards from 1995 to 2015 were linked to climate and weather including floods, storms, heatwaves and droughts.

UNISDR is focused on achieving stronger recognition of disaster risk reduction and climate change adaptation as essential elements of climate risk management and sustainable development.

UNISDR‘s efforts ensured that the links between disaster risk management and climate change adaptation were elaborated during the decisions taken around loss and damage at the November, 2013, COP19 (Climate Change Conference of the Parties) in Warsaw, Poland. Governments adopted the Warsaw International Mechanism on Loss and Damage associated with Climate Change Impacts with a focus on developing countries that are particularly vulnerable to the adverse effects of climate change. One of its stated functions is to enhance knowledge and understanding of comprehensive risk management approaches.

Link mechanisms for monitoring and reporting of linked goals and indicators

Align targets and indicators across agreements. Allow for a systematic monitoring of the contribution of disaster risk reduction to sustainable development through agreeing to disaster risk reduction-related indicators across the SDG targets aligned to indicators to be established through the Open-ended Intergovernmental Working Group on indicators and terminology for disaster risk reduction.

The formulation of any adaptation or resilience related goal considered at the 21st Conference of the Parties (COP) in Paris should build on alignment with goals agreed in


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the Sendai Framework for Disaster Risk Reduction. Sendai targets related to early warning systems and risk assessment and management have particular relevance.

Call for harmonized national reporting systems. To reduce the burden to countries reporting on international agendas, encourage harmonization in the design of the new generation of reporting tools and national reports to the UNFCCC, and the SDG reporting mechanisms. These should be complemented by commitments to measure risk systematically and strengthen existing national and global risk monitoring systems.

Promote and prioritize programmes and partnership that yield multiple benefits for sustainable development, disaster risk reduction, financing for development, climate action and urban development. Build on established partnerships established for disaster risk reduction and voluntary commitments made to implementation of the Sendai Framework for Disaster Risk Reduction.

2.7 PRINCIPLES AND INDICATORS OF INTEGRATED RISK GOVERNANCE

Since one cannot improve what cannot be measured, it is proposed to build consensus across a range of stakeholders and the ultimate beneficiaries on a set of factual and perception-based indicators that can help assess whether the framework conditions are in place for the 12 Principles to be effectively implemented in practice. In the more medium-term, such indicators could also seek to assess the effectiveness of governance instruments in place to address each of the Principles (OECD 2015b).

These Principles apply to all levels of government. They are clustered around three categories:

(1) Effectiveness of climate change governance relates to the contribution of governance to define clear sustainable water policy goals and targets at different levels of government, to implement those policy goals, and to meet expected objectives or targets.

(2) Efficiency of climate change governance relates to the contribution of governance to maximise the benefits of sustainable water management and welfare at the least cost to society.

(3) Trust and Engagement in climate change governance relate to the contribution of governance to building public confidence and ensuring inclusiveness of stakeholders through democratic legitimacy and fairness for society at large.

2.8 KEEPING ADAPTATION ON TRACK POST-PARIS

A new initiative on adaptation emerged out of the ground-breaking negotiations in Paris at the end of 2015. An Adaptation Committee was formed to produce guidance from a global stocktake of what adaptation activities already completed and underway. The first document should emerge in 2018 with and update in 2023 and every five years thereafter. Many of the details on how the process will work are still to be determined. The Committee‘s findings will inform adaptation communications from the UNFCCC and will include attention to where needs should be supported and successes and failures and the lessons learned shared by those engaged in adaptation activities. The Committee‘s mandate is to facilitate greater ambition toward adaptation among signatory countries to the Paris Agreement and to encourage a continued cycle of communication and improvement. Already the Committee has signalled the following as key attributes for improved success in adaptation (Dagnetet al., 2016):

Finding champions and making stakeholder engagement effective and incentivised

Mainstream adaptation into planning and monitoring and to capacity raising

Apply principles of social learning to establish efficientprocesses to resolve sustainability issues while meeting the goals of resilience and institutional capacity building


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Develop high levels of trust between all actors – civil society, private enterprise, government.

Encourage risk taking to extend learning opportunities

Focus on transparency to test new ideas and challenge embedded values

Attain high levels of citizen participation and improved governance structures to build communities of practice.

Figure 2.5: Review of the INDC submitted by India for the COP21.


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Figure 2.6: Climate change integrated risk governance performance components (modified based on OECD 2015b)

National governments will be required to report to the UNFCCC much like they do not

through the National Communication mechanism, NAP process and INDC but with explicit

and detailed reviews of how adaptation is being attempted and lessons learned across multi

sectors.

References

Bodansky, D. (2015). Crunch Issues in Paris.Opinio Juris. http://opiniojuris.org/2015/12/06/crunch-issues-in-paris/ Accessed 8 December 2015.

Climate Action Tracker Partners (2015).Climate Action Tracker.http://climateactiontracker.org/. Accessed 8 December 2015.

Dagnet, Y., Waskow, D., Elliot, C., Northrop, E., Thwaites, J., Modelgaard, K., Krnjaic, M., Levin, K., McGray, H. (2016).Staying on Track from Paris: Advancing the Key Elements of the Paris Agreement.Working Paper. Washington, DC: World Resources Institute. Available online athttp//www.wri.org/ontrackfromparis.

Ekholm, T.; Lindroos, T.J. (2015). An analysis of countries‘ climate change mitigation contributions towards the Paris agreement. VTT Technical Research Centre of Finland Ltd.

factor CO2 (2015). INDC Update No.6. 5 November. 2pgs

Jeffery, L; Fyson, C; Alexander, R; Gutschow, J; Rocha, M; Cantzler, J; Schaffer, M; Hare, B; Hagemann, M; Hohne, N; van Beevoort, P; Block, K. (2015). Climate Action Tracker (enlínea). Consulted on 15 Dec. 2015. Available at http://climateactiontracker.org/assets/publications/briefing_papers/ CAT_Temp_Update_COP21.pdf

http://opiniojuris.org/2015/12/06/crunch-issues-in-paris/

http://climateactiontracker.org/


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OECD (2015a). Climate finance in 2013-14 and the USD 100 billion goal, a report by the Organisation for Economic Co-operation and Development (OECD) in collaboration with Climate Policy Initiative (CPI).

OECD (2015b). OECD Principles on Water Governance, available online: https://www.oecd. org/gov/regional-policy/OECD-Principles-on-Water-Governance-brochure.pdf

Prinn, R. (2013) 400 ppm CO2? Add Other GHGs, and It‘s Equivalent to 478 ppm. Oceans at MIT News.http://oceans.mit.edu/featured-stories/5-questions-mits-ron-prinn-400-ppm-threshold

Roy, S. (2009). A spatial analysis of extreme hourly precipitation patterns in India. International Journal of Climatology. 29(3):345-355.

Turner, A. G. and H. Annamalai (2012). Climate Change and the South Asian Monsoon, Nature Climate Change 2: 587-595, doi:10.1038/nclimate1495.

vanVuuren, D. P.; and Stehfest, E. (2013). If climate action becomes urgent: The importance of response times for various climate strategies. Climatic Change 121, pp. 473–486.

Warrick, R.; Ye, W.; Li, Y.; Dooley, M.; Kouwenhoven, P.; Urich, P.(2013). SimCLIM 2013: A Software System for Modelling the Impacts of Climate Variability and Change. CLIMsystems Ltd. Hamilton, New Zealand.

Wigley, T.M.L. (in press). Intermediate radiative forcing targets and sea level stabilization.Proceedings of the National Academy of Sciences of the United States of America.

https://www.oecd/

http://oceans.mit.edu/featured-stories/5-questions-mits-ron-prinn-400-ppm-threshold



http://dx.doi.org/doi:10.1038/nclimate1495

http://dx.doi.org/doi:10.1038/nclimate1495


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3.0 CLIMATE CHANGE IMPACTS IN INDIAN COAST

3.1 INTRODUCTION

India has extensive and diverse coastal zone of more than 7500 km long. The coastal ecosystems play a complex and vital role in supporting economic prosperity and social welfare particularly for people living in those areas. The coast sustains the livelihood of millions of people and provides multiple ecosystem services that are essential for life.

Despite their tremendous ecological and economic importance, India‘s coastal ecosystems are under increasing pressure. There is also numerous direct and indirect pressures arising from different types of economic developments across the country. Major anthropogenic drivers of ecosystem degradation and destruction include habitat conversion to other forms of land use (e.g. wetland conversion and settlements on dunes and beaches) and the impacts of agricultural, domestic and industrial sewage and waste. Coastal habitats are also subject to powerful natural weather phenomena, such as cyclones, storm surges and, though infrequent, tsunami. Indirect drivers of ecosystem change include demographic, socio-political, cultural, economic and technological factors. It is clear, however, that the cumulative impacts of pressure on the coastal ecosystems are intensifying and India‘s economy and coastal population could be directly affected. Thus the major drivers of change, degradation or loss of coastal ecosystems and services are mainly anthropogenic. The threat of climate change is over and above this.

A number of recent studies (IPCC AR4, 2007) indicate that India is highly vulnerable to the consequences of Sea Level Rise (SLR).s. A 10% increase of the current 1 in 100-year storm surge level combined with an assumed 1m SLR could affect around 7.6 million people in India (Wheeler, 2011). The same study shows that India has the second highest population (out of 84 developing countries studied) affected by the potential effects of climate change. The affected population depend upon climate-sensitive sectors like fishing, agriculture and forestry for its livelihood.

3.2 GEOGRAPHIC SET UP OF INDIAN COAST

Coastal population in India is ~300 million out of 1.20 billion (Census of India 2011) and is growing at the rate of 2.0%, much higher than the average annual population growth rate of 1.5 % during 2001-2011. The 73 coastal districts 69 coastal districts (Figure 3.1) in mainland India; 3 in Andaman & Nicobar and 1 in Lakshadweep), have a share of 20% of the national population (Table 3.1) living within 50km of the coastline. The coast also includes 77 cities and towns, including some of the largest and most dense urban agglomerations - Mumbai, Kolkata, Chennai, Kochi and Visakhapatnam. India is one of the 10 most industrialized countries in the world. Recent reports highlight India as the 3rd largest economy in the World, and are growing at the rate of 5-6 % per annum. There are 13 major ports and 187 minor and intermediate ports along the India‘s 7,516 km (including island territories).

Coastal resources are increasingly being used for promoting economic growth and also as a sink for land-based pollutants. The dependence of coastal communities on diverse coastal ecosystems is acute in most of the developing countries and erosion of the capacity of these resources would setback the prospects of tackling poverty. Ministry of Economic Affairs (MEA, 2005) has reported that degradation coastal ecosystems could have uneven impacts on coastal communities.


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India is the sixth largest producer of fish with an annual potential yield of 3.92 million tonnes (CMFRI, 2011). An estimated 200,000traditional crafts carry out traditional fishing and there are about 35,000 mechanized fishing boats which are enhancing their fishing capacity annually.

About one million people in around 3650 villages of India situated along the coast are employed in marine capture fisheries. Indian fishery also supports several ancillary activities such as boat building, processing plants etc. All these features make this an important sector from the economic and social view point. The fisheries sector provides employment to more than six million people and accounts for 1.2% of India‘s total GDP.In addition to fisheries, the coastal environment is also of importance to other major economic and production sectors that include agriculture, tourism, ports and maritime shipping, other major transport and communication sectors and their related infrastructures. All these features make this an important sector from the economic and social viewpoint and have a great bearing on the economic sustenance and sustainable livelihoods of a large sector of population living in the coastal areas.

Table 3.1 Population of coastal states and UTs (based on Census of India 2011)

State and length

of coastline in km

Coastal Districts Population Average density of population

Gujarat (1600) Amreli, Anand, Bharuch, Bhavnagar, Jamnagar, Junagadh, Kachchh Navsari, Porbandar, Surat, Valsad

21198777 431 (in this Surat has 1376)

Daman & Diu (21) Diu, Daman 242911 1976

Maharashtra

(720)

Greater Bombay, Raigarh, Ratnagiri Sindhudurg, Thane

16243411 471(excluding GB which has 40333)

Goa (104) North Goa, South Goa 1457723 398

Karnataka (300)

Dakshin Kannada, Udupi, Uttar Kannada

4363617 300

Kerala (590)

Alappuzha, Ernakulam, Kannur, Kasaragod, Kollam, Kottayam, Kozhikode, Malappuram Thiruvananthapuram, Thrissur

26080036 1103

Tamil Nadu (1076)

Nagapattinam, Pudukkottai, Ramanathapuram, Chennai, Cuddalore, Kancheepuram, Kanniyakumari, Thanjavur, Thiruvallur, Thiruvarur, Thoothukudi, Tirunelveli- Kattabomman, Villupuram

28715588 638(excluding Chennai which has 26903)

Puducherry (41)

Yanam, Puducherry, Mahe, Karaikal 1244464 3103

Andhra Pradesh (974)

East Godavari, Guntur, Krishna, Nellore, Prakasam, Srikakulam, Vishakhapatnam, Vizianagaram, West Godavari

31705092 368

Odisha (480) Baleshwar, Bhadrak, Ganjam, Jagatsinghpur, Kendrapara, Puri

10381208 558

West Bengal (158) East Midnapore, Haora, North 24 Parganas, South 24 Parganas

29724862 1914


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The Indian coastal zone is rich in resources both living and non-living. The major among the

non-living resources are the thriving oil and natural gas, rare earth minerals, shell products,

etc. The extensive beaches and other coastal features attract a huge tourism industry. There

are several natural and manmade heritage and archaeological sites along the coast. In

addition many major cities like Mumbai, Chennai and Kolkata and large number of smaller

ones are situated along the coast.

Figure 3.1 Coastal States and districts of India (after NCSCM)

The infrastructure, industrialization and urbanization are currently at rapid pace along the coastal zones. Due to intensive development along the coast and consequent increase in population, the coastal zone has been facing several problems such as pollution especially due to increased nutrients, habitat modification, coastal erosion, conflicting use of land, decrease in biodiversity, depletion of fishery resources, harmful algal blooms. These problems have caused considerable damages along the coast.

Globally, as well as in India, there is an ongoing population migration to the coastal zone. This exacerbates continuing pressure on coastal resources and utilization. In the cities and towns where the density of population and developmental activities are on constant rise, the estuarine and coastal areas have been degraded more severely leading to irrecoverable loss of biodiversity. Prolonged changes over the years in the ecosystem especially due to disposal of wastes have caused decline in fish production.

These activities together with coastal structures including those of ports and harbors along with natural hazards cause moderate to extensive erosion in several coastal areas leading to considerable adverse impact effects not only to the coast and structures themselves but


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also to the various coastal economies. Siltation of navigational channels and river mouths all along the coast is a perpetual problem for ports, harbors, fish landing centres.

3.3 GEOMORPHOLOGY OF INDIAN COAST

The Indian coastline presents a complex picture with its long and varied geologic and geomorphic evolutionary phases. However, the latest picture we find is the result of the Holocene regressions and transgressions. The over 100 rivers of varied sizes flowing into the coastal sea and the dynamic marine environment decide the shape and character of the coastal area (Figure 3.2). Where the north east and north-west coasts have a large tidal range of over 4m, the southern coasts are influenced by only less than 1m tide.

The Gujarat coast in the northwest itself presents a complex geomorphology with extensive mudflats, bays, estuaries, creeks, mangroves, coral reef patches, cliffs, dunes, beaches, etc. The Maharashtra‘s northern coast is similar in nature. But south of Mumbai up to about central Karnataka are characterized by pocket beaches flanked by raised platforms, rocky cliffs, promontories, bays, estuaries and mangroves. The rest of the southwestern coasts of India present a uniform pattern with linear sandy beaches, small estuaries, spits, shallow lagoons and extensive barrier islands. The coastline is densely populated and is protected by seawalls at many stretches from coastal erosion.

Figure 3.2 The Important ecosystems of coastal India

The entire coastline of Tamil Nadu up to mid Andhra Pradesh on the southeast coast generally consists of linear sandy beaches, with an indentation at Vedaranyam and some reef patches towards the south. The northern Andhra Pradesh has two major rivers (Godavari and Krishna) joining the sea resulting in wide deltas. Residual rocky hills and ridges are common on this stretch. The Odisha is mainly depositional in nature formed by


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the major Mahanadi Brahmini-Baitarani river deltas. The Chilka here is the largest lagoon in India. The coast of Orissa is famous for its Bhitarkanika and other mangroves, the Olive Ridley turtle breeding grounds, the endangered horse-shoe crab habitats, etc. The West Bengal coast is deltaic due to the confluence of two major rivers, the Ganga and Brahmaputra. The Sundarban mangroves are world famous with an extensive coverage. The flat terrain is characterized by mudflats, estuaries, a large network of creeks, islands, etc. The Andaman & Nicobar and Lakshadeep islands also present an extensive coastline with mangroves, corals and other important habitats.

Among the various coastal geomorphic systems the beaches and sand dunes play an important role in maintaining the integrity of the coast. Disruptions to the sand balance through activities such as sand mining, near shore aggregate extraction and the construction of artificial coastal barriers in many locations are causing the total disappearance of beaches.

Table 3.2 Major coastal and marine ecosystems along the Indian coast (source: MoEF& ZSI)

Encroachment in dune areas often results in shoreline destabilization, resulting in expensive public works projects such as the building of breakwaters or seawalls and sand re-nourishment.

Deltas are high population and human land use areas and have been identified along with estuaries and small islands, by the Intergovernmental Panel on Climate Change (IPCC) as the coastal ecosystems most vulnerable to climate change and sea-level rise.

Among various types of coastal wetlands of India, tidal mudflats (23,620 sq. km) and mangroves (4,870 sq. km) have major share (Table 3.2). Wetlands are one of the most productive

ecosystems, comparable to tropical evergreen forests in the biosphere and play a significant role in the ecological sustainability of a region. They are an essential part of human civilization meeting many crucial needs for life on earth such as drinking water, protein production, water purification, sinks and climate stabilizers. The values of wetlands, like the cultural, economic and ecological factors, though overlapping, are inseparable.

3.4 CLIMATE AND CLIMATE CHANGE IN INDIA

As per the available Indian data, temperatures have been increasing, particularly in the night time and these may cause severe heat waves. Mean annual surface air temperatures show a significant warming of about 0.5 C/100 years during the last century. The significant warming trend is observed along the west coast, central India, and interior Peninsula and over northeast India. However, cooling trend has been observed in northwest and some part in southern India. The frequencies of large scale droughts or floods do not show any trend. The total frequency of cyclonic storms that form over Bay of Bengal has remained almost constant over the period 1887-1997. The sea level is rising at a rate of 1.30 mm/year during the past century.

The all-India mean monsoon rainfall does not show any long-term trend during the past century. However, small pockets of increasing and decreasing trends are observed. West coast, north Andhra Pradesh and north-west India show increasing trend in seasonal rainfall while decreasing trend is observed over east Madhya Pradesh and adjoining areas, north-east India and parts of Gujarat and Kerala (-6 to -8% of normal over 100 years). Frequency

Habitat Area (km2)

Mangroves 4445

Coral Reefs 5790

Mudflats 2961

Beach/Spit 1461

Marsh Vegetation 370

Mudflat with vegetation 6125

Beach Vegetation 25

Lagoon/ Backwaters 2132

Coastal Dunes 2509

Salt Pans 1617


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of intense rainfall events has been significantly increased. An increase in the rainfall over the west coast and northeast India is projected owing to the projected intensification of the heat low over northwest India, in spite of the projected weakening of the monsoon. This can increase major flood events and they can get reflected in the coastal areas when the rivers discharge.

The warming of the climate system has been termed ‗ unequivocal‘ as is evident from observations of increases of global average air and ocean temperatures, wide spread melting of snow and ice and rising average sea level. The IPCC has predicted a further rise in sea surface temperatures by up to 3°C at the end of the current century. Increasing global mean surface temperature, in general, leads to changes in precipitation and atmospheric moisture because of changes in atmospheric circulation, a more active hydrologic cycle, and increases in the water holding capacity of the atmosphere. Changes are expected in the frequency, intensity, and duration of extreme events, heat waves, heavy precipitation, and cold days. The consequences of sea level rise most likely to be experienced by India include: increased frequency and extent of flooding, rearrangement of unconsolidated coastal sediments and soils, increased soil salinity in areas previously unaffected, changes to wave climate and accelerated dune, beach and wetland (vegetation) erosion.

Table 3.3The projected change in global mean surface temperature and global mean sea

level rise for the mid- and late 21st century, relative to the 1986-2005 period for the 4 RCPs

that IPCC uses in their analyses (taken from IPCC, 2013).

Although much information exists regarding temperature and rainfall associated with climate observations, climate change projections for waves and storm systems remain largely under represented. Current comments relating to the surface of the ocean usually mention the likelihood of increased storminess with climate change, although this is disputed by some.

As SLR is a slow process (the current global mean is 3.3 mm/year, after Nerem et al, (2010), it takes a long time to see a change (however, the change in extreme events, where sea level is one element besides tide, wind, waves, air pressure, can be much more pronounced even on the short term). For this reason projection usually go out for 50, or even 100 years and beyond. Locally, SLR will differ from the global average as projected by the IPCC in the Assessment Reports (IPCC, 2013) because of the variation in local circumstances (currents, air-pressure, and thermal expansion). Long term tidal records can be used to estimate the local observed/experienced sea level rise.

It is possible to build on the CMIP5-data and the IPCC guidance document on constructing sea level scenarios for impact and adaptation assessment of coastal areas (Nicholls, 2011) while combining with various other data sources to produce projections of local experienced sea level rise including the effect of vertical land movement (using a spatial interpolation of continuous GPS measurements and tidal record trends). The data (Figure 3.4) show that there is a seasonal variation around the yearly mean sea level: July/August are about 10cm below that average level, while January-March are about 5cm above. There is no change in


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the seasonal variation from climate change (CLIMsystems, 2015). Near Mumbai (Figure 3.4) the vertical land movement is +1.11 mm/year (upwards), and under the RCP8.5-high

scenario, the projected SLR by 2100 is 106cm , based on an ensemble of 28GCMs.

Figure 3.3General circulation (climate) model (GCM) projections of global mean sea level rise relative to 1986–2005 for the four Representative Concentration Pathways (RCP) scenarios. The solid lines show the median projections, the dashed lines show the likely ranges for RCP4.5 and RCP6.0, and the shading shows the likely ranges for RCP2.6 and RCP8.5. RCPs usually refer to the portion of the concentration pathway extending up to 2100, for which Integrated Assessment Models produced corresponding emission scenarios. RCP2.6: One pathway, where radiative forcing peaks at approximately 3 W m–2 before 2100, and then declines. RCP4.5 and RCP6.0: Two intermediate stabilization pathways in which radiative forcing is stabilized at approximately 4.5 W m–2 and 6.0 W m–2 after 2100. RCP8.5: One high pathway for which radiative reaches greater than 8.5 W m–2 by 2100 and continues to rise for some amount of time (IPCC, 2013)

An intensification of tropical and extra-tropical cyclones, larger extreme waves and storm surges and ocean acidification also has been predicted by IPCC. These phenomena will vary considerably at regional and local scales, but the impacts are virtually certain to be overwhelmingly negative.

Sea Level Rise (SLR) is a relatively fast process, with the observed global mean rate between 1992 and 2015 estimated to be 3.3 mm/year (Nerem et al, 2010). Over a person‘s 50-year lifetime, the levels have risen by 17 cm and the rate is accelerating. Moreover, the frequency of a given extreme event is more pronounced: a small shift in the magnitudes on the extreme event distribution curve causes a big increase in frequency.


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Figure 3.4 Local experienced sea level rise near Mumbai, including vertical land movement (of +1.11mm/year), showing projection for 2020, 2040, 2060, 2008, 2100 (106cm), as well as seasonal variation (around the yearly mean).

3.5 IMPACTS OF CLIMATE CHANGE

The potential physical impacts of sea level rise are multitude (Nichols et. al., 2011):

i. Inundation, flood and storm damage (surge – sea, and backwater effect -riverine) ii. Long-term wetland loss (and change) iii. Altered patterns of erosion and accretion (direct and indirect morphological change) iv. Saltwater Intrusion (surface waters and ground-water) v. Rising water tables/ impeded drainage

In the absence of other impacts, coral reefs may grow fast enough to keep up with rising sea levels, but beaches may erode and mangroves, salt marshes, and seagrass beds will decline, unless they receive sufficient fresh sediment to keep pace or they can move inland (IPCC, 2013). The maximum growth rate under perfect condition for coral is about 4.5 mm/year. That rate of SLR will soon exceed this, so even without the impacts of erosion, coral bleaching and anthropogenic activities, corals are likely to decline.

Rocky shores, warming and acidification are expected to lead to range shifts and changes in biodiversity (IPCC, 2013).

Coastal freshwater wetlands are vulnerable to saltwater intrusion with rising sea levels, but in most river deltas local subsidence from non-climatic processes are more important (IPCC, 2013). A combination of cyclone intensification and sea level rise will increase coastal flooding while losses of coral reefs and mangrove forests will exacerbate wave damage (IPCC, 2013).

Impacts on land are compounded by coastal changes in sea level, increased frequency and magnitude of extreme events, as well as the resulting coastal erosion. Coastal and marine systems in Asia are under increasing stress from both climatic and non-climatic drivers (IPCC, 2013). Mangroves, salt marshes, and sea grass beds may decline unless growth and migration rates exceed SLR with the shift in the coastline, while coastal freshwater swamps and marshes will be vulnerable to the saltwater intrusion resulting from SLR (Table


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3.4). Coral bleaching caused by increasing water temperatures, as well as ocean acidification are expected to cause widespread damage to reef structures. Although marine biodiversity is expected to increase at temperate latitudes with warm water species expanding their ranges northward, it will decrease in the tropics as the thermal tolerance limits of certain species is exceeded (IPCC, 2013).

Table 3.4 Climate change impacts on mangroves

Climate variable Process affected Possible impacts

Rising atmospheric and sea temperature

Respiration Photosynthesis Productivity

Reduced productivity at low latitudes and increased winter productivity at high latitudes

Rising sea level Forest cover Productivity Recruitment

Forest loss seaward Migration landward (dependent on sedimentation and reclamation) Loss of salt marsh and mudflats

Increased storm frequency

Recruitment Sediment retention

Reduced forest cover, recruitment and sediment retention

Increased rainfall Sedimentation Groundwater recharge Less saline habitats Productivity

Flooding Increased diversity, productivity and recruitment

Reduced rainfall Sediment supply Groundwater recharge Salinity ingress

Loss of surface elevation relative to sea level Mangrove retreat to land; Reduced photosynthesis, productivity Species turnover and diversity

Altered coastal circulation

Habitats Sedimentation

Changes in coastal morphology Migration of mangroves Changes in biodiversity

As SLR occurs, inundation episodes from storm surges and flash floods will intensify (both in frequency and magnitude), while being compounded by the overtopping of waves during storms. This will also increase coastal erosion and in some cases lead to salt intrusion rendering soils unproductive.

The total projected sea level rise by 2100 could be more than a meter (106cm), based on an ensemble of 28 Global Climate Models and a high climatic sensitivity (RCP8.5).

Impacts of climate change including sea level rise and increase in the number of storm events will affect the natural stabilities of the beaches, dunes and mud flats.

Sea Level Rise has the capacity to exacerbate coastal erosion by promoting offshore transport of sediment (Table 3.5).

Along the migrating river mouths there are long shore parallel spits which are estimated to be especially vulnerable to increased sea level, wave energies and river flood flows.

Deltas are also potential areas of higher impacts of climate change.

Although mangroves are quite tolerant to changes in sea levels and salinities, it is likely that mangroves will be most vulnerable at the margins.

Also vulnerable are high energy erosion prone shorelines including areas of seawalls/revetments where sediment removal and natural recruitment of plants no longer occur.


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A rise in sea level would increase the accessibility of the backshore areas to waves. In shallow areas, the depth of the water itself limits the size of waves, which could be the most important impact of sea level rise along islands with steep shores. The primary natural causes of erosion in islands are related to sea level rise and storms. The climate change is expected to increase storms and it would further accelerate the coastal erosion.

Table 3.5 Climate change impacts on beaches and dunes

Climate variable Process affected Possible impacts

Rising temperature Breeding of species Changed productivity Changed species diversity

Rising sea level Morphodynamics Sedimentation

Changes in coastal structure Loss of habitats

Increased storm frequency

Morphodynamics Sedimentation

Flooding and erosion Changes in coastal structure

Increased wind and waves

Morphodynamics Sedimentation

Changes in coastal structure Beach erosion; dune building

Increased rainfall Ground water recharge Sedimentation Less saline habitats Productivity

Flooding and erosion Increased groundwater, bio-diversity, productivity and recruitment

Reduced rainfall Ground water recharge Sedimentation

Loss of habitats Salinity ingress Reduced productivity, species diversity

Altered coastal circulation

Habitats Sedimentation

Changes in coastal structure Changes in biodiversity

Global change and sea level rise threatens not only natural environments of coastal areas but also human population centres along low-lying Indian coasts. Climate change is also expected to be accompanied by an increase in the intensity of coastal storms. Sea level rise would increase the impact of tropical cyclones and other storms that drive storm surges. The effects would be disastrous on small island areas, estuaries, creeks, bays and such enclosed water bodies. Flooding due to storm surges will increase under conditions of higher sea level. As is true at present damage due to flooding will be most severe when the surges strike during high tide. Frequency of coastal flooding would be increased by a rise in sea level and changed by alterations to coastal current regimes, changed storm patterns and changes in rainfall which might enhance river based flooding in major river systems. It has been suggested that a general worldwide increase in inundation is expected during the next century.

For many coastal cities reliant at the present time on groundwater supplies, increasing sea levels will restrict the volumes of available freshwater and saline intrusion will increase. Such changes may result in changes to coastal vegetation. At present this is being experienced in many coastal areas of India during summer. These trans-boundary environmental issues need to be addressed in any strategic action plan.

Sea surface temperature (SST) is a critical physical attribute of coastal ecological systems. Water temperature directly affects process rates, water column stability, and the species of plants (such as algae, sea grasses, marsh plants, and mangroves) and animals (microscopic animals, larger invertebrates, fish, and mammals) that live in a particular region. Increases in temperature are thought to be associated with the degradation of coral reefs (bleaching) and may increase the frequency or extent of blooms of harmful algae. On longer time scales (decades to centuries), such changes may be related to variation in the supply of nutrients


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to surface waters from rivers and within the coastal waters and a cascade of effects from wide fluctuations in primary production to fish production.

3.6 ADAPTATION

Communities of plants and animals living in coastal areas are adapted not only to mean sea level but to regular short term changes on variability in sea level, which are associated with the tidal cycle and recurring seasonal changes. The monsoons for example, result in the mean sea level rise in Bangladesh about one meter higher in September than in March, a condition to which the mangrove ecosystems are adapted. It has been argued that even in the case of infrequent episodic events, the communities concerned are ―disturbance adapted‖ and that indeed disturbance may be necessary to maintain the biodiversity of some coral reef and mangrove communities. Some other contrary examples are nesting marine turtles and horseshoe crabs.

Mangrove ecosystems can function as a buffer zone and with sea level rise mangroves can gradually migrate towards land. The widespread conversion of mangrove ecosystems to other uses such as aquaculture, saltpans and rice production seriously reduces coastal protection against storms and wave erosion and reduces the rate of sediment accretion in coastal areas. Kerala has reclaimed several mangrove areas for paddy and coconut plantation. In such areas, the soils have become acid sulphate and the yield has reduced. Moreover, such areas will become more prone to inundation. Kharlandsof Maharashtra, ‗khazans‘ of Goa and ‗pokkali‘ of Kerala are examples. The bunds constructed across the wetlands and creeks destroying vast mangrove areas are attracting floods. Ultimately, the economic costs of continued rising of protective structures and pumping of water may outweigh the economic benefits which can be derived from continued use of the land concerned. Continued protection is the only available option to low lying areas of the country.

Coastlines are dynamic and the net gain or loss of coastal land under the impact of these processes can change over a long term period. Observing the coastline for decadal periods enables scientists to understand the natural dynamic equilibrium that exists. A shorter observation period (monthly, annual or even decadal) might erroneously conclude that there is a net erosion (or accretion). These natural fluctuations in coastal dynamics are upset by human activities such as the construction of ports, hard coastal defences, breakwaters, all of which have strong impacts that can be experienced far away from the actual structures. The slow change introduced by SLR can complicate matters the situation can nucleate to dramatic changes.

Hard coastal defences, such as sea walls, protect settlements at the cost of preventing adjustments by mangroves, salt marshes and seagrass beds to rising sea levels. Landward buffer zones that provide an opportunity for future inland migration could mitigate this problem (IPCC, 2013). More generally, maintaining or restoring natural shorelines where ever possible is expected to provide extended coastal protection and other benefits (IPCC, 2013).

Adaptation involves initiatives and measures that reduce the impact of climate change. Adaptation focuses on reducing the vulnerability of natural and human systems against climate change effects. Policies should be designed to address present day problems in coastal zones with a view to strengthening the natural capacity of coastal systems to respond to changes. In addition, such policies provide for the sustainable use of the renewable resources and hence, even in the absence of climate change, such policies would provide benefit to future generations.

Mitigation and adaptation are two ways by which climate change phenomenon can be reduced. Mitigation includes methods to reduce greenhouse gas emissions and to enhance


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sinks. It is an attempt to reduce hazards. Mitigation addresses the problem at its source. This is mainly a political process. Adaptation involves initiatives and measures that reduce the impact of climate change. In other words, adaptation focuses on reducing the vulnerability of natural and human systems against climate change effects.

Depending on the time and type of response, adaptation can either be reactive or anticipatory, private or public, planned or autonomous as identified by IPCC.

Adaptations can be short term or long term, localised or widespread. In unmanaged natural systems, adaptation is autonomous and reactive and is the means by which natural systems respond to changed conditions. Integrated climate risk management would need to include elements of anticipatory risk management (ensuring that future development reduces rather than increases risk), compensatory risk management (action to mitigate the losses associated with existing risk) and reactive risk management (ensuring that risk is not reconstructed after disaster events).

Some examples of anticipatory responses in coastal areas in natural systems are increased ecosystem management including biodiversity conservation, protection and conservation of coral reefs, mangroves, sea grass and littoral vegetation, development of legislation for coastal protection and research and monitoring of coastal and coastal ecosystems.

Some examples of anticipatory responses in coastal areas in human systems are establishing new building codes for multi hazard-proof houses, instituting hazard insurance, installing early warning systems and evacuation systems, more cyclone / storm surge / flood shelters, integrated coastal zone planning which includes establishing set-back zones (regimented implementation of CRZ, more teeth to these regulations and ICZMP implementation all along, particularly in urban and populated areas by strengthening the institutional framework), enhanced water management (eg. larger culverts and drains particularly in the urbanized areas), improving coastal defences through greenbelts and hard structures (topping up of present coastal protection structures, appropriate elevated design for new structures, elevated foundations for all new structures, mangrove afforestation landward of the existing clusters, mangrove planting in new areas, sand dune protection with natural vegetation, etc.), relocating threatened buildings, phasing out development in exposed areas, creating upland buffers and rolling easements, new agricultural practices, such as using salt-resistant crops, desalination systems and exploring Indigenous options in coastal agriculture, fisheries and housing.

Examples of reactive actions in natural systems are, relocation, changing occupation, changing insurance premium, offering compensation or subsidies, enforcing building codes, promoting soft structures like dune or wetland restoration or reinforcement as buffer, beach nourishment, green belts, biodiversity conservation, public awareness to enhance protection of coastal and marine ecosystems and promoting hard structures like dykes, sea-walls, tidal barriers, detached breakwaters, revetments, groins, floodgates, tidal barriers, beach/wetland nourishment.

Some of the options are ―no regret‖ options. These options have more than one benefit and therefore need not be linked to climate change alone. For instance sand dune, wetland and mangrove conservation or reforestation contribute to soil water conservation, biodiversity conservation and give food, fodder and other produce to coastal communities, besides acting as carbon sinks. In today‘s vulnerability scenario, adaptation in coastal areas is inevitable. Anticipatory adaptation measures are more effective and less costly than reactive adaptation. They reduce the vulnerability and strengthen the response capacity.

Adaptation measures should consider local knowledge and decisions, solutions, actions by the local communities. Most actions require shorter period with smaller costs and larger benefits. Some of the examples of adaptation measures include structural and non-structural


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interventions such as shore protection measures, capacity building and technology interventions. However, these measures should be consistent with the economic and social development and environmental conservation.

In many coastal areas current economic and social activities are exacerbating an already critical situation. Potential impacts of climate change and sea level rise are overshadowed in many areas by existing environmental problems. Current environmentally unsound development practices will increase susceptibility to predicted climate change impacts. Some coastal states are particularly vulnerable. For example, between eight and ten million people live within one metre above sea level in each of the unprotected deltas and coastal areas like the Sundarbans and Orissa. Every year the Bay of Bengal experiences a number of cyclones and floods in the major rivers. Mangrove forests which are in a good condition protect human life and properties from cyclones and floods. The impact of a super cyclone of Orissa on mangrove and non-mangrove regions has once again proved the significance of mangroves and shelter belts.

The economic costs of coastal protection and water regulation may be prohibitive for India. Alternative strategies which maximize the natural protection afforded by ecosystems such as sand dunes, natural beaches, mangrove forests and enhanced natural rate of sediment deposition may be the only possible mechanisms for mitigating the potential impacts of rising sea level. It would be unwise to undertake flood protection measures by means of embankments, especially where subsidence is taking place since these will become increasingly more expensive to maintain in the face of continued sea level rise. Therefore, activities such as encouraging silt deposition through mangrove replanting may not only be economically a better response, but also prove in the long term to be a more environmentally sound option.

Coastal ecosystems can play a valuable role in absorbing the impacts of climate change, so we can reasonably anticipate that the value of these coastal systems as buffers will increase in the coming decades. Greater appreciation of coastal resources also can result in positive changes in governmental regulations. Social safety nets and the creation of alternative livelihoods can be an important element of reform. These reforms can be integrated with poverty reduction programs and other instruments of economic and social development.

References

MoEF and ZSI.Gaps in coastal and Marine Biodiversity studies in India. Online at http://moef.nic.in/downloads/public-information/gaps-in-coastal-and-marine--biodiversity-studies-in-india.pdf

Wheeler, 2011

Nerem et al, 2010

IPCC 2007

IPCC 2013

Nichols et. al., 2011

CLIMsystems, 2015

http://moef.nic.in/downloads/public-information/gaps-in-coastal-and-marine--biodiversity-studies-in-india.pdf

http://moef.nic.in/downloads/public-information/gaps-in-coastal-and-marine--biodiversity-studies-in-india.pdf


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4.0 SHORELINE MANAGEMENT AND EXISTING GUIDELINES

4.1 PRESENT STRATEGY OF PROTECTION OF INDIAN COAST In India as per the latest assessment of NCSCM, MoEF (Annual Report, 2013) about 358 km of coastline is affected by high erosion and 1189 km by medium or low erosion. Most of the high erosion zones are actively retreating and some in spite of coastal protection. As of now about 625 km of the coastline is already protected (Table 4.1) by hard structures (mainly seawalls or groynes). Area lost or seriously impacted by coastal erosion is estimated by CWC is about 450 ha per year. All the coasts do not require protection. If we look at the Indian coastline only one-fifth is reported to be subjected to erosion at high or medium level. This means that the rest of the coast is generally stable and in some cases undergoing even accretion. Hence there is no need to protect these coasts with any structures. Only intervention, if at all, required is to preserve these beaches and its associated geomorphic systems such as coastal dunes, spits, barrier islands, mangroves, etc. These will also help in building resilience to climate change and associated sea level rise. For the eroding coasts four approaches are normally adopted. Where there is no habitation or infrastructure under threat ‗do-nothing‘ is the option. The general concept is that even though a coast is presently undergoing erosion, unless there are serious manual interventions it may stabilize on its own. In the second sparsely populated case where the inhabitants or infrastructure affected is minimal it will be more viable to ‗retreat‘ or relocate the affected people, infrastructure and other investments under risk to safer locations in the backshore. The ‗retreat‘ option also becomes unavoidable when the erosion is very severe and detailed scientific evaluation reveals that no protection measure can really help in restoring the beach or protect the affected objects. The third option is to ‗protect‘ and needs to be adopted when the area is highly populated and when expensive infrastructure is threatened. The options may be hard structures, soft measures or hybrids. The hard measures normally adopted are seawalls, groynes, revetments, dykes, berm breakwaters, etc. The soft measures include beach nourishment, sand bye-passing, dune restoration, etc with borrowed sand often strengthened with sand-filled geotextile bags and vegetation. The last option is ‗advancing to offshore‘. When the objects to be protected are invaluable like defense establishments, historical / heritage monuments / areas, etc or when there is a need to create an area for ports, city expansion (when there is no area available inland), recreation / tourism purposes, etc this option is resorted to. For this the waves are regulated at a distance in the offshore by constructing detached breakwaters, artificial reefs or other similar structures with hard or soft materials.

Coastal protection in India traditionally followed the engineering manuals of the US Army Corps of Engineers / Coastal Engineering Research Centre (CERC) Shore Protection Manual (US Army, 1984) which is updated periodically. A pioneering effort to put the coastal engineering practice under one roof was done by NIO (Bruun&Nayak, 1984) prior to accurate climate change models and scenarios. A similar effort with more emphasis on Karnataka was done by Karnataka Regional Engineering College (KREC, 2001). For the first time in India, the KREC document gave a detailed account of the soft measures of retreat,


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nourishment, sand bypassing, sand dune protection / rehabilitation, vegetative measures, etc.

Another set of guidelines was produced within the framework of the ―Indian-Netherlands Water and Coastal Management Co-operative Programme 2002-2003‖. This provided a framework for a number of Indian-Dutch co-operative activities in the field of Integrated Coastal Zone Management. The guideline presented the entire spectrum of hard and soft coastal protection measures and highlighted the relationship between integrated management and the various coastal protection methods. It presented erosion in a broader context and discussed how anti-erosion measures can be integrated into a general and sustainable approach to coastal development. It introduced three strategies for erosion: (1) retreat, (2) accommodate and (3) protect. The Guideline describes the measures that can be taken for each strategy, with technical maintenance and protection methods for eroding coasts.

CWPRS is the accredited Government agency to give advice and to design coastal protection works.It brought out a Technical Memorandum on ‗Guidelines for Design &Construction of Seawalls‘(Kudale and Sharma,2010).The goal of the document was not to account for climate change impacts or specify the best coastal protection methods to be adopted in a given situation. However, a list of other methods of shore protection was included. These guidelines were based on the vast experience of CWPRS in the design of coastal protection works, both in practice and in the laboratory.

It gave detailed consideration to the practical difficulties / deviations encountered during the design and construction of seawalls, with essential precautions to be taken. Deviations that may occur during design and construction were: position of seawall, under-design of armours, toe protection, inadequate or no-provision of filters, overtopping due to underestimation of design wave or the maximum water level, rounded stones, weak pockets, discontinuities in sea wall, armour in single layer and/or pitched. Lastly, the planning of a construction programme and maintenance of coastal structures wereconsidered.

Central Water Commission (CWC) through the Coastal Protection and Development Advisory Committee (CPDAC) periodically provides guidance to the coastal engineering community about the policies, approaches and guidelines to be followed in the coastal protection works. As part of the National Coastal Protection Project (NCPP)an attempt has been made to compile and bring out guidelines exclusively forpreparation of coastal protection projects through a publication titled "Guidelines forpreparation of coastal protection projects".

Table 4.1 Status of Shore Protection including soft solutions along the Indian coast

No. State (and length of the coast in km*)

*Erosion /protection in km**

Protection measures adopted

1 West Bengal (158)

125 / 81

Generally seawalls and revetments; Groins near Subarnarekha inlet; Digha-Shankarpur Development Authority have constructed a seawall using geotubes to combat dune erosion, for a stretch of about 800 m, between Shankarpur and Mandarmani; social forestry near Subarnarekha inlet.

2 Odisha (476.4)

107.55 / 10

Generally seawalls and revetments; forestry activities in Bitharkanika and Gahirmatha coasts.

3 Andhra Pradesh

65.7 / 20.45

Generally seawalls and revetments;Visakhapatnam Port Trust has engaged Dredging Corporation of India (DCI)


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(973.7) to nourish the RK Beach, Visakhapatnam by bringing dredged material from new Ssnd trap of the Port.

4 Tamil Nadu (906.9)

151.81 / 75.62

Generally seawalls and revetments; Groins at some locations like Ennore, Royapuram and many places in the south, egKanyakumai; Dune management by social forestry in the Thinnelveli and Tuticorin districts. Mangrove management at the Nagapatnam-Vedaranyam coast; Shore parallel geotubes planned at Cuddallore

5 Puduchery (30.6)

9.50 / 3.20

Generally seawall and revetment; Beach restoration programme for Pondicherry initiated by MoES

6 Kerala (569.7)

478.14 / 346.75

Generally seawalls; groins at some locations;Based on a study coordinated by NCESS & IITM transitional T-groin field was recommended for shore protection for the Panathura coast near Thiruvananthapuram - two T-groins out of the recommended groin field were implemented on a pilot basis; The first multipurpose artificial reef built using geotextile bags filled with sand was implemented at Kovalam in 2010.

7 Karnataka (280)

249.56 / 56.77

Generally seawalls and revetments; Nearshore berms and offshore reef being implemented at Ullal under SCPMIP; Another eight locations are selected for seawalls, groins, dunes and nourishment under SCPMIP.

8 Goa, Daman & Diu (160.5)

19.18 / 5.15

Generally seawalls and revetment; Perched submerged breakwaters at Daman.Nearshore geotextile reef and beach nourishment for a length of 800m at Candolim in 2010; Dune management programme at Utroda-majorda and Miramir (Goa); beach nourishment at Coco (Goa); offshore reef at Colva (Goa);

9 Maharashtra (652.6)

263 / 127

Generally seawalls and revetments; Groins at a few locations; Social forestry and mangrove rehabilitation under a GEF-UNDP project; Geotextile tube was deployed at Devbagh (Malvan) as temporary protection for 150 m long coast; Nearshore geotextile tube reef and beach nourishment provided for 900m long coast at INS Hamala, Mumbai in 2010; Offshore geotextile reef together with nourishment was provided for 400m long coast at Dahanu; Submerged reef and beach nourishment implemented at Mirya Bay (Ratnagiri).

10 Gujarat (1214.7 )

155 / 22.3

Generally seawalls and revetments along the south Gujarat coast and at Dwaraka. A Task Force appointed by the Government has taken up preparation of a Master plan for coastal protection for the State

11 A & N Islands(1962)

Revetments and seawalls

12 Lakshadweep Islands (132)

132 / 73

Mainly tetrapod embankments; Dune management in Chetlat island.

* As per CPDAC, CWC website (**Coast affected by erosion / and protected)


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4.1.1 Draft National Strategy for Coastal Protection

The Draft National Strategy for Coastal Protection is a document prepared by the National Centre for Sustainable Coastal Management (NCSCM) of the Ministry of Environment, Forests and Climate Change (MoEF&CC). The objective was to help policy makers and coastal managers to take appropriate decisions with respect to coastal protection. Thus, the target audience includes a broad range of stakeholders such as the government, non-governmental organizations, the private sector, industries and coastal communities. In addition to coastal erosion, climate change is also considered, e.g. sea level rise, storm surge, salt inundation etc. which will displace people and degrade coastal ecosystems.

Following the Dutch collaboration, the concept of the ‗Sediment Cell‘ is advocated. The sediment cell is a section of coast where beach sediments are mostly contained within that zone and there is very little transfer of sand to adjacent zones. This concept is valuable because it defines the physical range of potential impacts, which is equal to the size of the cell. The sediment cell is now widely used to define the size of the zone which needs to be considered when determining impacts of a proposed development.

The strategy paper also documents the techniques and practices for coastal protection under three broad categories: (i) accommodate, (ii) retreat and (iii) protect. Being a broad national strategy paper, there are no specific recommendations for the best methods to protect coasts.

An earlier report prepared under the chairmanship of Dr.M.S.Swaminathan (MoEF, 2005) similarly highlighted the need for an integrated approach to deal with the coastal zone. The Strategies and Guidelines for national implementation of the ICZM were drafted by NCSCM to further facilitate this process (NCSCM, 2014). The document provides another foundation layer to bring an integrated approach to India, and provides an important baseline for our Guidelines being prepared to deal with Climate Change.

4.2 COASTAL REGULATIONS

Strategies and policies that integrate decisions for the Indian coast provide a sound basis for balancing the resource allocation for the coast zone. A balance is envisaged for economic growth, protection from natural hazards, social use and environmental sustainability.

There had been several attempts by the Government of India to bring order to the development of the coastal zones. However these regulations did not account for climate change probably due to the lack proper guidelines for the same. The larger programs on Integrated Coastal Zone Management (ICZM), with the support of World Bank and the initiation of innovative coastal protection approaches supported by the Global Environment Facility and Asia Development Bank (ADB) were the other outcomes to account for the impacts of climate change.

4.2.1 Environment Protection Act(1986)

The Environmental Protection Act (1986) provides regulations for protection and improvement of the environment and for matters connected with the environment. The Act is an umbrella legislation designed to provide a framework for Central Government coordination of various central and state authorities. It was established under previous laws, such as the Water Act and the Air Act.

4.2.2 Coastal Regulation Zone Notification(2011)

To overcome problems associated with the above guidelines, MoEF introduced the CRZ notification (MoEF, 1991), which contained mandatory regulations governing any proposed


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development in the coastal area. The CRZ had a major impact on controlling developmental activities in the coastal areas. The impacts of coastal erosion was also viewed in a different perspective and softer solutions for the ecologically sensitive areas (CRZ-I) and less developed areas (CRZ-III) were considered.

In order to determine the barriers for the implementation of the CRZ and to have a strategy for coastal management, MoEF brought out a strategy document (MoEF, 2005). This recommended some changes in the regulatory framework of CRZ. Among the changes recommended to be incorporated there was impacts of climate change and sustainability of the interventions protecting and conserving coastal ecosystems. Some 6 years later, these recommendations resulted in the new CRZ Notification (MoEF, 2011).

The Coastal Regulation Zone Notification (2011) declared the following areas as coastal regulation zones (CRZ):

land area from High Tide Line (HTL) to 500 m on the landward side along the sea front;

land area from HTL to 100 m inland or the width of the water body (whichever is less) on the landward side along tidally-influenced water bodies;

land area falling between the hazard line and 500 m from HTL on the landward side, in case of seafront and between the hazard line and 100 m line in case of tidally-influenced water bodies;

land area between HTL and Low Tide Line (LTL) and the water and bed area between LTL and the territorial water limit (12 nautical miles) in case of sea, and the water and bed area between LTL at the bank to the LTL on the opposite side of tidal influenced water body.

Here High Tide Line (HTL) is defined here as the line on the land up to which the highest water line reaches during the spring tide, without consideration of other sea level influences. The Low Tide Line (LTL) is the line on the land up to which the lowest water line reaches during the spring tide.

The industries, waste disposal, reclamation, mining and few such activities, which disturbs the fragile coastal ecosystems are declared as prohibited within the CRZ with some exemptions essential for the economic development and livelihood security of the region. The exemptions include permission to reclaim land required for setting up, construction or modernization or expansion of foreshore facilities like ports, harbors, jetties, wharves, quays, slipways, bridges, road on stilts, and such as meant for defense and security purpose and for other facilities that are essential for activities permissible under the Notification: measures for control of erosion, based on scientific including Environmental Impact Assessment studies; maintenance or clearing of waterways, channels and ports, based on EIA studies; and measures to prevent sand bars, installation of tidal regulators, laying of storm water drains or for structures for prevention of salinity ingress and freshwater recharge based on studies carried out by any agency to be specified by MoEFCC.

Areas that are ecologically sensitive and geomorphologically important such as mangroves and corals and dressing or altering the sand dunes, hills, natural features including landscape changes for beautification, recreation and other such purpose which are important in the context of climate change are to be protected as per the Notification. The land use and development in areas that have been developed up to or close to the shoreline (CRZ II), areas that are relatively undisturbedusually in the rural areas (CRZ III) and the water and seabed up to 12 nautical miles from the LTL (CRZ IV) are regulated.

The declaration of 200m area from HTIL in CRZ III as a No Development Zone (NDZ) is one step towards adaptation against the possible impacts of climate change. However, the permission for certain activities other than for livelihood including settlements will have far reaching consequences in the light of climate change impacts.


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The CRZ also prescribes a Hazard line, which is being demarcated by the Survey of India to regulate certain activities. The Hazard line takes into account tides, waves and sea level rise and shoreline. The land area falling between the hazard line and 500m from HTL on the landward side is included in CRZ. There is still an uncertainty on how to incorporate regulations within it when they are made available.

4.2.3 Island Regulation Notification(2011)

The Island Regulation Notification 2011 is issued by the Ministry of Environment and Forests to regulate the activities in the ecologically sensitive Islands of Andaman and Nicobar (A and N) and Lakshadweep. It declares the coastal stretches of A and N and Lakshadweep and their water area up to the territorial water limit as the Islands Protection Zone (IPZ) and restricts the areas from the setting up and expansion of any industry, operations or processes and manufacture or handling or storage or disposal of hazardous substances.

As per the Notification, Environmental management for the Islands of Andaman and Nicobar (A and N) and Lakshadweep shall be managed as follows: The entire island of A and N other than the four islands Middle Andaman, North Andaman, South Andaman and Greater Nicobar and all the islands of Lakshadweep shall be managed as per Integrated Island Management Plans (IIMP) to be prepared by the respective Administration with the support of research institutions.

In view of the large geographical area, the islands of Middle Andaman, North Andaman, South Andaman and Greater Nicobar shall be managed as per the Island Coastal Regulation Zone (ICRZ); with categorization as done for mainland coast.

4.2.4 Environment Impact Assessment (EIA) Notification (2006)

This Notification(MoEF, 2006)makes it mandatory for some projects or activities to have prior environmental clearance for implementation. All projects and activities are broadly categorized into two categories - Category A and Category B, based on the spatial extent of potential impacts and potential impacts on human health and natural and man-made resources. Permission shall be obtained from the MoEF on the recommendations of an Expert Appraisal Committee (EAC) for category A projects. For Category B project, approval is at State-level through the State Environment Impact Assessment Authority (SEIAA). They take recommendations at the State or Union territory level from a State Expert Appraisal Committee (SEAC). There‘s a wide range of activities requiring full EIA assessment. This includes the construction of ports, harbours, coastal protection infrastructure, coastal tourism and others.

4.3 SHORELINE MANAGEMENT PLAN

The SMP sets out the strategy for the protection of the coastal communities and theresources for a specified length of the coast. The strategy takes into account the natural coastalprocesses, human influences, land use and other environmental aspects. A detailed understanding of the problems and needs in the coastal zone, best understanding of the constraints and limitations and support of the user groups and local communities are required. SMP defines the nature and magnitude of risks from coastal hazards. The SMP provides a large-scale assessment of the risksassociated with shoreline evolution, sea level rise, coastal flooding and erosion against a backdropassociated with the challenges of environmental and economic development and presents a policy framework to address these risks in a sustainable manner.

A Shoreline Management Plan (SMP) will be a large-scale assessment of the risks associated with coastal processes (as described above) and will help to reduce these risks by properly planning the coastal protection and management of the landuse. For an SMP to


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be successful it should be based on a participatory planning and management system at all stages from conceptualisation to implementation.

Thus the aims of the SMP are:

Identify the areas of conservation, preservation and protection and examine the causes of coastal erosion and coastal instability.

Consider the measures for conservation, preservation and protection and the viability of future coastal protection infrastructure for the most vulnerable and feasible locations using appropriate technologies.

Consider locations where natural protection measures can be considered such as developing dunes and planting of mangroves and other vegetation for protection.

Consider wider coastal management issues including social, economic and developmental requirements.

Ensure that the SMP aligns with the aspirations of the people which can be achieved by stakeholder engagement and improving awareness of coastal issues.

The SMP shall be based on participative planning, professional design and the use of modern technology.

To achieve this the objectives of SMP shall be:

Identify the best and most sustainable ways to manage coastal resources and risks, including those due to climate change, over the next 100 years.

Identify social and economic aspects relevant to the coastal zone.

Indicate how future plans and activities of stakeholders may affect the shoreline and how shoreline management can be relevant to such plans.

Support the planning system (CRZ, EIA and CC Guidelines) to minimise inappropriate developments in the long term.

4.3.1 Determination of Shoreline Management units

The entire coastline will be divided into sediment cells which are defined as a length of coastline relatively self-contained as far as movement of sand and other sediments are concerned, and where interruptions of such movement will not have a significant effect on neighbouring sediment cells. The boundary of a sediment cell generally coincides with larger estuaries or prominent headlands. Each sediment cell (as per the detailed demarcation provided by NCSCM) or sub-cell is divided into smaller management units, which are suitably sized for development of shoreline management sub plans.

Criteria for Sediment Cells

Primary Cells: Coastal geomorphology, sources of sediments, stores of sediments, interface of rocky-sandy-muddy coast

Secondary Cells: Changes in littoral front, change in coastal alignment, decadal erosion / accretion, man-made littoral barriers, tidal inlets / river mouths, delta front

Management Units: Coastal landuse, fishing related activities, erosion / accretion / protection measures, proposed development plans, sediment input from rivers, industrial areas, settlements, tourism areas, other coastal activities, polluted areas / salt pans / aquaculture / salt water intrusion, dredging and reclamation, sand / other mining areas, marine protected areas, ecologically sensitive areas, elevated areas, defense areas, archaeological / heritage sites, CRZ boundaries


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Based on the sediment cells and management units identified the landward boundaries are required to be decided. It has to be based on the geomorphology, landuse, the hazard zoning and CRZ demarcated by MoEFCC and the administrative jurisdiction of the village or Panchayat. This system of zoning provides a basis for deciding the uses and measures that will protect and enhance the character of distinctly different shoreline areas and for uniformly applying policies and use requirements within these areas (Ramanamurthy et al, 2004). 4.3.2 Process of Development of SMP

Once the zoning and its characterization is completed the strategies or policy options for consideration in each zone can be worked out. Monitoring the coastal processes and modelling be adopted for predicting the changes to the coast and for testing different alternatives for protection and management. The standard options normally adopted are: do nothing, retreat, accommodation and protection. SMP policies need to be considered for key time related policy ‗windows‘ to consider long-term coastal changes also due to climate change. For this SMP policies will take into account existing regulatory policies such as the CRZ and EIA over the short-term with cognisance of management over the next 100 years to accommodate the climate change impacts. The plan and policy for each management unit for the long term can be developed as recommended in the present Guidelines for Climate Resilient Coastal Protection and Management. Detailed SMPs needs to be prepared through continuous inter-sectoral consultation and public participation for its acceptability. Thus the different stages in the development of SMP are:

Stage 1: Scope of the SMP: formalising arrangements for production of the SMP

Stage 2: Assessment of the management units and initial stakeholder engagement: undertake a review of coastal processes and behaviour to develop baseline scenarios and consider the different policy scenarios over various timescales, and develop knowledge based from stakeholder engagement for each management unit.

Stage 3: Policy review and development: assessment of policy scenarios for identification of policies for each management unit.

Stage 4: Stakeholder engagement: consultation of key stakeholders and the public to ensureparticipation in the development of the policies and approval of the draft and final SMPs.

Stage 5: Finalise the plan: finalise SMP taking into account of stakeholder responses and overall approval.

Stage 6: Implement the Plan: after approval the SMP needs to be formally adopted by key stakeholders and institutions and incorporated within the planning framework for achieving long term sustainable coastal management objectives.

Stage7: Post monitoring: After implementation regular monitoring of coastal morphology and processes should be done for predicting climate change impacts and for providing modifications to the SMP.

Table 4.2 Status of SMPs for the Indian coast

1 West Bengal World Bank funded project for preparation of ICZMP and SMP initiated for all three coastal sectors in West Bengal (Sundarban sector, Haldia sector and Digha-Shankarpur sector)

2 Odisha SMP was prepared by ICMAM PD for the Gopalpur coast during the 11th Plan period (2007-2012); World Bank funded project initiated for preparation of ICZM Plan for the Paradeep-Dhamra (80km) and


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Gopalpur-Chilika (116km) sectors and SMP for the whole Orissa coast.

3 Andhra Pradesh

Not reported

4 Tamil Nadu Model ICZM plan was made for the coastal zone from Pulicat to Mamallapuram by ICMAM PD during 9th Plan period (1997-2002). SMP was made by ICMAM PD during the 10th Plan period (2002-2007) for the sector from Ennore to Pulicat. ICMAM PD very recently has prepared SMP for the Royapuramcoast located north of Chennai.

5 Puduchery Beach restoration programme for Pondicherry initiated by MoES

6 Kerala SMP prepared by CESS for a 120 km sector of the South-central Kerala coast during 2004-2007. ICZMP was prepared by CESS for a 22 km sector of Southern Kerala during 2000-2001; SMP was prepared by CESS for (i) the Muthalapozhy sector extending from Thumba to Nedunganda between Veli inlet in the south and Varkala cliffs in the north in southern Kerala and (ii) Vadanapally sector from Munambam inlet to Chettuva inlet in the Central Kerala during the 11th Plan period (2007-2012).

7 Karnataka SMP prepared for four sites viz. Devbhag (Karwar), Pavinkurve (Honnavar) KundapurKodi (Kundapur) and UliargoliPadukere (Malpe) by the ICMAM PD in collaboration with NIO during the 2007-2012; SMPs prepared very recently for the whole state under the ADB funded Sustainable Coastal Protection and Management Investment Programme (SCPMIP).

8 Goa, Daman & Diu

Model ICZM plan was made for the Goa coast by ICMAM PD during 9th Plan period (1997-2003).

9 Maharashtra Preparation of SMP for Sindhudurgis taken up under the ADB funded Sustainable Coastal Protection and Management Investment Programme (SCPMIP) for Maharashtra.

10 Gujarat Model ICZM plan was made for the Gulf of Kachchh by the ICMAM PD during the 9th Plan period (1997-2002). World Bank funded project for preparation of ICZMP has again been initiated for Gulf of Kachch. A task Force is preparing an Integrated Coastal protection program for the south Gujarat coast as part of the preparation of a Master plan for for coastal protection for the whole State.

11 A&N Islands NCSCM has prepared an Integrated Insland management plan (IIMP).

12 Lakshadweep Islands

CESS prepared ICZMP for Lakshadweep islands in 2007; CESS also prepared Integrated Island Management Plan (IIMP) as per CRZ 2011 Notification for all islands.

Several attempts have been made in the country for the development of SMPs. Integrated Coastal and Marine Area Management (ICMAM) Project Directorate of MoES has successfully preparedthe SMPs forselected sectors of the Indian coast (Table 4.2). The ADB assisted Sustainable Coastal Protection and Management Project (SCPMIP) has developed Draft SMPs for all the three coastal districts of Karnataka. Maharashtra also has come out with a Draft Interim SMPfor the Sindhudurg district. 4.3.3 Integrated Coastal Zone Management (ICZM) The coast is a highly dynamic interface between land and sea influenced by land-based and oceanic processes. Since most development-related activities are sector-specific and highly competitive, there is often conflict for space and resources. This creates pressure on the natural ecosystems, as the demand for space is high for various activities, causing extensive destruction and degradation to coastal ecosystems. Integrated Coastal Zone Management


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(ICZM) is adopted to reduce the conflicts and pressures and to ensure sustainable development. The Shoreline Management Plan (SMP) thus forms an integral part of ICZM.

While managing management of the coastal area has to be firmly rooted in the Regulations, ICZM provides a larger perspective for development-related activities, successful implementation of the CRZ and conservation of coastal ecosystems. It also provides a platform for the integration of environment and socio-economic concerns with development activities.

The Government of India agreed to adopt an Integrated Coastal Zone Management (ICZM) approach and has developed a vision for the long-term management of the coastal and marine areas, as articulated in the National Environment Policy (2005) and in the M.S.Swaminathan Committee report (2005). The vision has two parts - (a) reforming the regulatory framework for integrated management of the coastal and marine areas and (b) developing the institutional arrangements, capacity and adequate knowledge systems to enable the desired shift to ICZM approach.

The primary goal of ICZM is the reconciliation of development objectives, conservation aims and protection from hazards in the coastal and marine sector. The objectives of ICZM are to help achieve:

i. Security of lives life and property in disaster-prone coastal zones; ii. Conservation, preservation, restoration and development of coastal resources and

ecosystems; iii. Livelihood security of coastal communities and overall food security; iv. Security of cultural and heritage sites and v. Sustainable development and national growth.

ICZM requires a multidisciplinary approach, as no single sector can adequately address these issues. Therefore, the objectives of ICZM primarily include a primary focus on safety and security including national security, security of life, lives and properties, of ecology, culture, and heritage and of livelihood for of coastal communities . The first such a Plan is being now implemented in Odisha under the MoEFCC‘s ICZM Project supported by World Bank.

4.4 CONCLUSIONS

India has legislated against coastal degradation but still the coast is undergoing negative environmental impacts. A large portion of the Indian coast is undergoing erosion and more than half of coast is protected with hard measures such as seawalls and groins. The beaches in these locations are slowly disappearing making the infrastructure vulnerable. However, where the beaches are better conserved like in Goa, the erosion is less and the demand for protection is minimal in that State. Demand by the engineers for protection is greater in the other States.

The following questions need to be addressed:

Is erosion a new fact of life that will require billions of Rupees and high quality planning to cure?

What are the drivers of extensive erosion – natural or induced?

How can shoreline management plans and integrated management of the coastal zone be applied also in the context of climate change?

The existing regulations and practices provide a good basis for developing guidelines for climate change resilience.There are no documents which compare the performances of


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various coastal protection methods being adopted in India, and so understanding the effectiveness of these measures is a priority for sustainable outcomes.For strategic planning of the coastal protection and management projects and for proper regulations in the light of the climate change scenario there is a need to make some amendments in the existing CRZ and other regulatory regimes in India.

References

CRZ Notification 2011.Ministry of Environment and Forests, Government of India. http://www.moef.nic.in/sites/default/files/7_0.pdf

The Environmental Protection Act, 1986. Ministry of Environment and Forests, Government of India, http://www.moef.nic.in/sites/default/files/eprotect_act_1986.pdf

Island protection Zone Notification 2011, Ministry of Environment and Forests, Government of India http://www.moef.nic.in/sites/default/files/so20e.pdf

Environmental Impact Assessment Notification 2006, Ministry of Environment and Forests, Government of India, http://www.moef.nic.in/legis/eia/so1533.pdf

Bruun, P &Nayak, P. (1980). Manual on protection and control of coastal erosion in India, NIO , Goa, 80p

KREC (2001). Manual on coastal protection, Coastal Engineering Research Group, Department of Applied Mechanics & Hydraulics, Karnataka Regional Engineering College, Suratkal, Karnataka, 38p

Kudale M. &Sarma AS. (2010). Technical Memorandum on guidelines for design and construction of seawalls, CWPRS, Pune, 23p

Mathew, J. (2010). Strategic alternatives for coastal protection: multipurpose submerged reefs. Presentation in the eleventh meeting of the Coastal Protection and Development Advisory Committee(CPDAC), Chennai

MoEF (1983). Environmental guidelines for development of beaches, 38p

MoEF (1991). Coastal Regulation Zone Notification, 20p

MoEF (2005). Report of the Committee to Review the Coastal Regulation Zone notification, 127p

MoEF (2011). Coastal Regulation Zone Notification, 28p

NCSCM, MoEF (2014) Strategies and Guidelines for national implementation of Integrated Coastal Zone Management, 156p

NCSCM, MOEF, (2015) National Strategy for Coastal Protection – draft, 44p

US ARMY Corps of Engineers, Coastal Engineering Research Centre (1977). Shore Protection Manual, vol.1, 2 & 3


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CRCPMP TRAINERS TRAINING

25-27 JULY 2016

5.0 CLIMATE CHANGE ADAPTATION GUIDELINES FOR COASTAL

PROTECTION AND MANAGEMENT IN INDIA

5.1 INTRODUCTION

These Guidelines are defined here as ‗scientifically well-founded suggestions to deal with a

changed climate at the coast‘.The phrase ―no regrets‖ (which means that decisions taken

today will not be regretted in the future) adequately describes the need and purpose of the

Guidelines, which foster better planning to deal with climate change impacts. Guidelines are

not regulations, but they may provide a baseline for any future regulatory changes.

The primary goal of the Guidelines is the development and fostering of sustainable methods

to protect coasts in India, which can be adapted to climate change impacts. The Indian

coastline has already been subject to anthropogenic and environmental pressures that have

altered the local area causing erosion, sedimentation, etc. Current coastal protection

measures in India often result from emergency responses to a hazard event, which may lead

to ad hoc approaches creating unplanned coastal protection of varying quality. There is a

need for effective and strategic decision-making to limit climate change impacts to the

coastline through a strategic approach.

This Guideline is not intended to be an engineering design manual. The goal is to provide

the information to enable effective decisions in the present to prepare for an uncertain future,

and where a ‗no-regret‘ approach is needed. The importance of the social and environmental

aspects of future climate change cannot be overstated, particularly in coastal environments.

However, these issues are not the focus of these Guidelines and are dealt with, for example,

by relevant coastal planners, economists, ecologists, and resource managers during the

design and implementation of any adaptation strategy.

The Guidelines are approached in two parts:

The first part considers ―Regulatory Guidelines‖ which are procedural and may be put in place by government departments, while some may require legislative/judicial approval to be enforceable.

The second part focuses on ―Intervention Guidelines‖, which are based upon recommendations for best-practice methods to protect the coast.

Neither element can be successful without the other, as regulations have no substance

without practical solutions, and solutions may not be feasible without a regulatory

framework.Within the two broad categories, several sub-categories of Guidelines are

proposed:

Regulatory Guidelines:

Administrative guidelines: Recommendations to strengthen elements of the approval processes;

Economic guidelines: Dealing with financial assessments and cost-benefit of climate resilient coastal protection measures;


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Land use guidelines: Regulations for the public departments on the land use focusing on coastal protection, building offsets, public use of the land;

Mining and dredging guidelines: Sand resources and uses;

Environmental impact assessment guidelines: Intensity of studies, consideration of the environment, monitoring and environmental risks;

Ecological guidelines: Protect the natural ecosystem flows and function.

While many regulations already exist in the Coastal Regulation Zone (CRZ), the coast is

struggling to remain natural (natural refers to the maintenance of the pre and existing eco-

system services) and many beaches are eroding. Throughout India most State Departments

with responsibility for the coast say that more than 50% of their shoreline needs to be

protected now to save them from the impacts of climate change, i.e. prior to higher sea

levels, bigger and more frequent storms and more population along the coast. The

regulatory challenge is therefore substantial. However, in developing the Guidelines, it is not

sufficient to recommend new regulations without context. Each regulation should aim to

embody an anticipated outcome, and by examining the effectiveness of the existing

regulations and their enforcement, informed decision-making for the future is contextualized.

Intervention Guidelines

The Intervention Guidelines incorporate an understanding of a range of intervention

strategies that can be considered to address climate change impacts at the coast. At this

stage it is emphasized that climate resilience cannot be handled independently. A basically

unscientific design can never be made climate resilient. Hence these guidelines are for

holistic and at the same time climate resilient protection and management of the coast. This

is a guide for coastal planning and management to complement India‘s efforts on integrated

coastal zone management, specifically recommending options for protection, based on case

studies of existing methodologies.

These are Draft Guidelines as agreed in the work program of the project. Appendices are

provided to support for Guideline implementation with considerable background information

from India and abroad, which defined the way forward. The supporting information and

background to the main document is contained in appendices. With the various interests and

skills among the readership, the appendices are designed for specialized training, school

lessons, selection of coastal protection structures and even a tool to help practitioners use

the broad information brought together in this study. For example, some readers may be

unable to comprehend the equations and physics of coasts and waves, while others may

show strong interest in economics or beach dynamics and so the various topics are dealt

with in separate appendices.

An important criteria within the Guideline is the difference between ―hard‖ and ―soft‖

solutions. These are defined more fully elsewhere, but ―soft‖ solutions basically work with

sand to provide the required protection. ―Soft and hard‖ solutions with best global and Indian

practice are considered and an ―Environmental Softness Ladder‖ is presented to help the

reader rank the softness of existing coastal protection methods.


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5.2 REGULATORY GUIDELINES

A Administrative Guidelines

Decisions for coastal infrastructure development in India are often the responsibility of

different departments. There is currently no compulsory requirement to ensure that all

projects in the same sediment cell are referred to and discussed when a new project seeks

approval. They can operate independently. The goal of this guideline is to ensure forward

planning for climate resilience and to avoid duplication, overlap, contradictions, negative

fallouts, etc.Central committees have been established (e.g. National Coastal Zone

management Authority and Committees for EIA /CRZ clearance) which can enforce

compulsory recognition of multiple projects from different departments. The present approval

process and later the monitoring process do not enforce this strictly.This may lead to

transference of the damage done to the beach by one department to be paid for by another

department. This is happening all along India‘s coastline.

Guideline A1: Develop a structure to have compulsory cooperation/consultation

between departments, ministries or agencies which have control over specific

aspects of the coast

Contracts in India are strong, but variable. Designers will often undertake detailed studies

but later the implementing agency might change the design without such intimate

knowledge. Moreover, the department undertaking the works may need to take more

responsibility for negative effects. Currently, a designer may be asked to do the ―best

possible‖ solution within the project constraints and budget. And the designer may note that

negative impacts are likely to occur. However, there is no responsibility back to the

implementing agency for such impacts.

Guideline A2: The roles and responsibilities of designers, implementing agencies and

contractors should be clarified in a standard contractual agreement

Notably, the design of coastal structures is complex and requires years of training and so a

balance must be struck between community engagement and the need for professionals to

be responsible for the design of coastal structures. In thepast, projects have been

essentially secret, even though the Right to Information Act allows access to documents.

Google Earth has also allowed people to see the effects of projects, once the project has

been built. The original consulting reports and other documents may be difficult to procure.

Moreover, the project may have identified negative impacts without the public having access

to this information.

Guideline A3: Develop a central web-based repository for designs and plans to be

made accessible to the public

Though there are provisions included in the agreements and contracts related to coastal

projects implementation, often they are found inadequate or not followed up resulting in

compromises in the quality of the projects.

Guideline A4: Develop a set of rules for monitoring the progress during and after

implementation of the project.


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B Economic Guidelines

Projects in India are based on the construction cost, land or income loss only. However,

every project will have maintenance costs, offset benefits and sometimes downstream

impacts that lead to more expenditure. The environmental costs may be substantial. Losses

of beach amenity, fishing access, degradation of the coastal ecosystem and public distaste

for poor coastal protection measures all play a role in project value. Even simple factors like

public health are influenced when residents are unable to take a stroll on the beach in the

morning and evening. Much of the coastal protection in India is focused on protecting the

―front row‖ of houses or infrastructure. A broader spectrum of issues needs to be engaged in

the decision making so that the shared resources of the coastal zone are all enhanced.

Guideline B1: Account for both the economic and environmental costs and benefits of

coastal management strategies in order to ensure the most beneficial use of the

shared resources of the coastal zone.

Projects in India are based on the construction cost,land or income loss only. However,

every project will have maintenance costs, offset benefits and sometimes downstream

impacts that lead to more expenditure. As such, the full cost of the project is never known.

Decisions are taken on the initial capital costs without an allowance for the long-term costs.

For example, a rock seawall may be built because it‘s considered to be the cheapest form of

coastal protection. However, the long-term costs may be substantial with maintenance of the

wall, need for bigger rocks in the future as the beach disappears and repairs to the beaches

through nourishment. Currently, seawalls are popular for their low initial cost but they may be

actually more expensive than other forms of coastal protection over the full life cycle if the

economic, environment and social costs were included with the maintenance.

Guideline B2: Use full life-cycle cost analysis, not just construction cost (triple bottom

line economic, environment and social cost). The full-life cycle cost incorporates the

costs of climate resilience, maintenance, environmental flows, downstream impacts

and other costs (social to be included) that may arise due to the structure over its full

life-cycle. Benefits may be accrued to offset costs, e.g. environment, beach

restoration, infrastructure, public amenity etc.

The selection of sites for reparation has been at the discretion of local Coastal engineers in

most states. They prepare the lists which are then submitted for funding. Such decisions are

often at sites where the erosion is caused by anupstream structure and funding for these

sites may be the responsibility of the party at fault (polluter pays principle). Moreover, the

benefits need to be clearly identified and costed. The guidelines have set a low target of 5:1,

which can be calculated knowing the real estate value or other benefits. These benefits

should be five times larger than the cost of the project. The goal is to discourage frivolous

applications and to demonstrate that applications have fully considered the need for the

project. The cost to be offset by benefits should be the full life cycle cost.

Guideline B3: Coastal protection projects should have a minimum benefit: cost ratio

of 5:1 over the full-life cycle (Training on life-cycle cost analysis is part of our project).


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C Land Use Guidelines

Under Climate Change, several processes including storm surge, wave run-up and elevated

water levelsare projected to alter. Larger storms with bigger waves are predicted during

cyclones. Thus, the inverse barometer, coastal storm surge, surf zone set up and swash will

be larger.Wave climates are expected to change strength and direction and so an allowance

is needed for potential coastal erosion.An intermediate additional water level allowance of

0.7 m for sea level rise is also forecast (IPCC, 2013).

While these numbers are underpinned by scientific calculations, there is some uncertainty

about storminess and water level rise in the year 2100. The Indian research institutes are

providing further input to the predictions and so Table 5.1 may be modified once those

results become available. Only one water level has been specified, but the likely over-

topping is known to vary around the coast of India. Cyclone prone areas are particularly

vulnerable and will need to consider a higher level.

Current storm surge levels vary significantly from around 7 m in the northeast to less than

0.5 m in the southwest.On the east coast, Orissa experiences levels of 5-7 m while on the

west coast Gujarat experiences 2-3 m. Thus, the values in Table 5.1 are mostly relevant to

Karnataka. Further refinement of this Guideline will come when the full studies of storm

surge under climate change are completed.

Table 5.1 Breakdown of water levels defining the land construction elevation

Parameter Present day Elevation allowance

Elevation allowance withClimateChange (2100)

Erosion allowance 0 0.5

Low pressure inverse barometer 0.3 0.35

Coastal storm surge (wind driven) 0.4 0.45

Surf zone set-up 0.6 0.7

Wave run-up (swash) 0.6 0.7

Elevated level under Climate Change 0 0.7

Adjacent to a river?

TOTAL 1.9 m 3.0 m

Guideline C1: No new construction on land above beaches that is less than 3.0 m

above HTL as defined in CRZ and demarcated in the CZMP, including roads and other

government infrastructure. If a river is adjacent, then the 3.0 m must be supplemented

by river flood levels in a climate change scenario.

As the cost of property and the pressure of population grow, it becomes more difficult to fix

problems at the coast due to existing dwellings. The 50 m allowance is much smaller than

the likely erosion of the beaches in the absence of shore protection works in the event of

climate change impacts at vulnerable stretches. However, our consultation suggests that a

larger distance may not be enforceable.


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We recognize that the goal of blocking construction near the coast is already covered under

the CRZ regulations. While the full 200 m may not be enforced, our experience suggests that

the first 50 m is the most important to allow for Climate Change.

Guideline C2: No maintenance or extension approvals will be given to existing

buildings within 50 m of the crest of the primary sand dune or the berm crest of the

beach, or HTL, whichever is further landward. All must be removed within 5 years.

Government programs should not be exempt in the 50 m zone, including roads and

infrastructure.

While construction is allowed in zones with natural isobaths of 3.0 m elevation, the floor

levels on new buildings need to be at least 1.0 m above that elevation to eliminate

floodingand overtopping (Table 5.1). Structures on piles have been adopted in parts of

America and Australia. The lower level forms a temporary room or provides storage, but the

walls must be constructed from fragile materials that will allow the floods and wave action to

pass unhindered below the main building.Only one water level has been specified, but the

likely over-topping varies around the coast of India. Cyclone prone areas are particularly

vulnerable and will need to consider a higher level. Our CoastTool software aims to provide

levels for individual beaches or districtsaround India. An additional allowance will be needed

in locations adjacent to rivers.

Guideline C3: Approved buildings within the CRZ must have a minimum floor level

above HTL which is greater than the storm surge levels for the location plus 1 m

above HTL.

Unless the beaches are restored, the only alternative for India will be to build barricades

against the sea around the whole country. For millions of years, the beaches and duneshave

been protecting our coasts, with waves breaking offshore, rather than on the rock seawalls

or other barricades. ―The beach is the best form of coastal protection‖.

However, once other hard structures are placed along the shore, the dune and beach are

nearly always lost. In these cases, restoration of the dune is very difficult to achieve and can

only be done with large-scale beach nourishment programs.

Notably, dunes are not large on most of the Indian coast, particularly on the west coast due

to the lack of strong winds to bring the sand from the berm to the dune. The development of

a dune with nourishment provides a buffer of sediment which the natural forces can re-align

as the climate changes.Well-nourished beaches are not expected to erode under climate

change if the sediment supply is maintained either artificially or naturally.

Guideline C4: Primary sand dunes should be restored and elevated to at least 3.0 m

above the high tide levelplus local storm surge levels

Dunes on their own, without vegetation, are not very stable. The planting and fencing allows

the dune plants to become established. Wind-driven sand is then more easily captured and

the dune will grow in height. Walking on the dune breaks the plant roots and prevents the

dune from properly establishing and growing. The pilot studies are demonstrating dune

reclamation and planting


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Guideline C5: Dunes should be maintained through vegetation plans and protected

with simple fences with public access pathways no closer than 100 m

The high tide line is an important delineator as it sets an upper sea level due to tides alone.

This level will vary around India and needs to be defined. The low or mean tide levels are not

as useful for defining building levels as they need to be accompanied by the tidal range

information. We appreciate that considerable work is underway in India to delineate the high

tide line.

Guideline C6: The HTL should be delineated (being completed for the whole country

by MoEFCC) and incorporated into Coastal and Shoreline Management Plans

The need to educate and make people aware of risks is paramount before they will engage

in dealing with Climate Change. This guideline ensures that people think through the risks

and find solutions in their applications for structures.Example risks includecoastal erosion

caused by storms and long-term processes, coastal inundation caused by storms or

inundation from high tides due to sea-level rise and overtopping. Financial risks include

downstream impacts, losses of fishing access and illegal construction in the CRZ.

Guideline C7: All applications for new structures should consider risk from current

and future hazards including the impacts of climate change and natural hazards.

D Mining and Dredging Guidelines (Extractive Activities)

While many communities and regulators are aware of the need to keep the sand on the

beaches, the price of sand and the pressure to find sand for building has risen. However, as

the beach is the main natural protector of the coast, the overall costof coastal protection will

be extremely high if the beaches are lost. The works along the coast with maintenance are

already costing more than the price of the sand and these works will become more

expensive when they need to be stronger and bigger to defend against sea level rise and

stronger storms in the future. The costs for putting rocks along the foreshore are

exponential, i.e. as the beaches erode and larger waves attack the seawalls, the rock size

must increase and the cost of large rocks is rapidly increasing while the sources are

becoming scarcer with the closure of quarries and restrictions on rock transport.

The following guideline is of fundamental importance for the future of India‘s beaches and

sand removal regulations need to be strictly enforced. Sand should not be removed from the

sediment cell, but it may be necessary to re-position sand within the same cell.

Guideline D1: All removal of sand from the CRZ zone to land from the rivers, beaches

and offshore should be stopped, except for beach and dune nourishment with sand

derived from within the same sediment cell including offshore sand deposits noting

that removal from offshore sources is prohibited activity under the present CRZ

notification.

Dredging of navigation channels sometimes requires temporary storage. However, the

requirement to return this sand to the littoral system needs to be enforced within 12 months

of storage. Longer times may be too late as erosion could occur during the first monsoon.


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Guideline D2: No sand (including sand from the CRZ exempted activities like

navigational channels or inlet shoal dredging) should be put onto land, except for

temporary storage convenience, and it must be returned to the beaches within 12

months.

If sand is bypassed around structures or sand from feeder systems like lakes and rivers is

placed downstream, the effects on downstream beaches are minimized. The 5 m depth

relates to the littoral zone where most beaches receive waves of sufficient size to bring sand

shoreward from 5 m depth. This depth is also convenient for dredge operators as it‘s

normally well beyond the surf zone.

Guideline D3: Sand removed from the updrift side of structures, seabed, lakes,

estuaries or any other water bodies connected to the sea should be deposited on

downstream beaches in depths no greater than 5m.

Ports and harbours are having a large impact on the coast. The 5 m depth is convenient for

discharge operations as it‘s well beyond the surf zone. Studies have shown that waves will

be able to bring the sand shoreward on most beaches. If the wave climate is very small then

the 5 m depth may need to be reduced. The 500 m restriction relates to the need to feed

sand to the beaches immediately downstream of the port, thereby preventing erosion in the

most impacted zone.

Guideline D4: Dredged sand from ports will be placed in depths no greater than 5m

and within 500m of their entrance in the downstream direction of the littoral drift.

While this may be difficult to enforce, some countries insist that any excess sand from a

building site is put to the beach. It‘s a small volume usually and so this guideline is not a

priority restriction.

Guideline D5: Extra sand excavated during building construction within the CRZ

should be placed on the beach.

Currently, operators are helping to fund their operations by selling sand. This sand belongs

to the Government and community. While the most appropriate plan is to prohibit any sales

or capture, there will be situations where the construction of a coastal barrier leads to

accumulation, e.g. the port at Mirya, Maharashtra. If a levy is applied per m3, greater care

will be taken to design the ports and other structures in a way that minimizes capture. It will

also discourage the use of sand for reclamation. Exemptions would include coastal

protection structures which are designed to capture sands for beach protection, unless those

structures created problems downstream.

Guideline D6: Sand trapped by coastal construction will be subject to a levy per cubic

meter, payable to the local / district authority and the sale of sand should be

prohibited (the provision in the present CRZ should be strictly enforced).

E Environmental Impact Assessment Guidelines

An EES is designed to identify problems before they occur. For example, a coastal structure

which blocks sand movement, the EES should identify those problems, pose solutions or

account for it in the full life cycle costing of the project. Decisions can then be made in the


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full knowledge of the system and impacts about whether the structure should be built.

Currently, EES documents may be too limited in their brief and limited in their spatial scope.

Guideline E1: A full Environmental Effects Statement (EES) including climate change

impacts must be provided before any construction approvals are given.

Climate Change needs to be specifically addressed so that coastal projects can ameliorate

any future impacts. This might include structure heights, rock sizes or likely erosion impacts

under a changed climate or bed levels.

Guideline E2: The Environmental Effects Statement must address climate change

adaptations (options through risk assessment and benefit analysis).

These guidelines are relevant to current projects, although they are focused on future

impacts. We have prepared a form for the applicant and government to complete which

helps them to focus on the guidelines and their benefits for future projects.

Guideline E3: The applicant will address the Guidelines specifically (in the EIA or EES

and in the project Terms of Reference)

The many case studies in this document indicate that hard structures can be successful at

the site being protected but they may create substantial impacts downstream which are

ultimately detrimental and costly.

The environmental softness ladder is designed to encourage the use of soft solutions, with

sand-based solutions like beach nourishment taking priority. Ultimately, the beaches are

made of sand and the best approach for the future is to slowly build up the sand reserves on

the beaches over the next decades in preparation for climate change. Sand reserves will

then be available to reduce or eliminate erosion and create a natural environment along

India‘s coasts.

Each solution is ranked according to its likely environmental impact. Seawalls receive the

least number of points because they are unsuitable for changed climate conditions when

water levels and waves are larger during cyclones.

Groynes have a lower impact than seawalls, but low-crested groynes are ranked softer than

the traditional groynes with a high crest. The latter acts to block longshore transport and can

have a stronger environmental impact downstream than the low-crested groynes which fill to

a level and then allow the residual sediment to pass over the top unhindered.

Offshore solutions are in the middle of the ladder. These allow the beach to grow seawards

as a widening of the beach (known as a ―salient‖) in their lee. They act on the waves which

cause erosion, rather than trying to deal with the effects at the shoreline.

Guideline E4: In relation to the selected shore protection methodology, projects will

be allocated bonus points according to the Environmental Softness Ladder.

Every site has different elements. It may be on the east or west coast, or in the far north

where tides are larger, waves are smaller and the seabed is more muddy. Some sites

havevariations like the presence of headlands versus a long straight beach. It‘s not possible

to transfer all coastal protection solutions from one site to the next. For example, a


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groynefield may be successful in one location but the same groyne field may be unsuitable

at a site with different longshore transport, wave heights, net sediment flux or wind climate

regime.Each study needs to reconcile the conditions at the site in question. Even though

experience from other sites will remain relevant, a design needs to be carefully blended with

the environment under threat.

Guideline E5: Designs must be site specific and based on a clear understanding of

the coastal processes and the sediment cell concept which shall be clearly mentioned

in the report.

One of the key factors determining the type of solution to be used is the longshore transport

rates. In locations where the net flux is close to zero, an offshore solution or nourishment is

likely to be best. In locations with strong longshore transport in one direction, then groynes

might be successful. It‘s imperative that every site be defined by the longshore transport

fluxes which can be calculated using computer models or empirical equations. Long-term

time series of waves are now available for most of the world‘s coasts, including India. These

come from the combination of satellite observations, wave buoys and computer models

which can accurately hindcast wave conditions over decades.

Guideline E6: The long-term stability or instability in response to positive or negative

rates of sand supply will be identified (comprehensive EIA based on long term

monitoring).

Computer modelling of coasts has reached a very sophisticated level. These models allow

forecasts of outcomes to be determined prior to construction. However, if they are casually

used without calibration data then they may not be reproducing the conditions at the local

site. Models have become readily available off the shelf but the background and training of

the modeler is not uniform. The modeler and the field data collection and analysis will need

peer review to prevent cursory model studies being undertaken.

Guideline E7: Proposed coastal construction projects must be examined using best

practices (computer modeling) techniques, with ample peer-reviewed data collection

prior to approval.

Any solution at a beach is expected to have some impact. This guideline stresses the need

to understand the sedimentary system, sediment cell and to undertake sufficient studies

which inform about likely effects. Any modelling project must be underpinned by data

collection and quality analysis of that data.

Guideline E8: Beach partitioning by any structure (e.g. groynes, nearshore reefs)

must be cognizant of the compartment sizes, downstream beaches and the complete

sediment cell. A detailed analysis must be provided based on best practices

(computer modeling) techniques with substantial supporting peer-review data

collection.

Ongoing monitoring and maintenance are necessary for most coastal projects to assure

continued acceptable project performance. The most important aspect in any monitoring

program is to determine the purpose of the monitoring. Project performance/function

monitoring consists of observations and measurements aimed at evaluating the project's

performance relative to the design objectives. An essential component of any plan is a


68

provision for gathering sufficient baseline data, as it will provide the basis for meaningful

interpretation of measurements and observations. Structural condition monitoring provides

the information necessary to make an updated assessment of the structure state on a

periodic basis or after extreme events.

Guideline E9: Establish an ongoing and appropriate process of monitoring and

evaluation and obtain a fool-proof commitment from the proponent.

The training provided to professionals will vary with the discipline. For example, the engineer

will take a strong interest in the structural aspects, while the scientist will be more

determined to find the underlying causes of erosion and to match the solution with the

environment. In India, decision making about coastal protection has mostly remained with

engineers, many of whom have been transferred from irrigation / public work / dams/ road /

harbour schemes to beaches. While the system requires such a dynamic, this can lead to

decisions being taken by engineers with no formal training in coastal processes or coastal

engineering. Coastal engineering is different from most other forms of engineering. The

coast and its dynamics are unique and all engineers are not exposed to a formal training.

The proposed technical committee, consisting also of other relevant disciplines such as

environment and socio-economics, will be most suitable for making a realistic assessment of

the situation and arriving at the most well-rounded decisions.

Guideline E10: Designs should be reviewed and approved by a technical committee

consisting of at least one expert recognized by the Centre or State from each of these

categories: a coastal scientist, engineer, environmentalist, and socio-economist.

F Ecological Guidelines

The assessment of effects should deal with the marine eco-systems. Indeed, some projects

such as offshore solutions may enhance the fishery and thereby score bonus points for the

project during the evaluation.

Guideline F1: The environmental effects on coastal eco-systems including the sand

dune/beach ecology must be studied as part of the required Environmental Impact

Assessment.

Mangroves are suitable for low energy coasts and particularly on the banks of the inland tidal

water bodies, as they entrap sediments which can provide storm surge and sea level rise

benefits over long periods. The same mud can also eventually lead to the loss of the water

body due to infilling and eventual reclamation. Great care needs to be taken with the

management of mangroves. The siltation encouraged by the mangroves should not

eventually lead to the loss of the water body due to infilling and eventual reclamation.

Guideline F2: Mangroves cannot be considered as a reliable barrier against coastal

erosion or sea level rise on the open sandy sea coast but can be encouraged in

muddy coasts, inland tidal water bodies and mud flats

Many projects could pro-actively enhance the marine eco-system. For example, rocks well

placed can create habitat. Sheltered zones behind reefs can provide a more stable substrate


69

for some species. In addition, beach nourishment can be beneficially used to enhance

shoreline species of plants and animals which may also assist birds and wildlife in some

locations.Ad hoc benefits need to be formally specified with action plans to implement any

benefits.

Guideline F3: Coastal ecosystem benefits must be defined, and ways for their

adaptation to the planned developments should be identified along with an

implementation plan.

5.3 INTERVENTION GUIDELINES

G Coastal Protection Guidelines

The project proponent will need to consider all options with a high environmental softness

which enhances climate resilience prior to proceeding up the ladder to the harder solutions.

If an option lower on the ladder is considered unsuitable then arguments to support that

decision will need to be presented. The goal is to encourage the use of softer solutions,

while retaining the rights of the designer to appeal for a harder solution in certain cases.

Guideline G1: Coastal protection measures should not interrupt free movement of

sand along the beaches. Methods with a higher softness index (e.g. dune care or

nourishment) should be considered before proceeding higher up the “Environmental

Softness Ladder”.

Beach structures which capture sand deplete the total sand budget along a beach. In some

cases with large net sediment transport, the amount captured by the structure may be small

by comparison and nourishment may not be required. The project proponent will need to

provide sufficient evidence to allow the project to proceed without nourishment.

Guideline G2: New coastal protection structures should be accompanied by beach

nourishment to bring the system to equilibrium, rather than relying on the capture of

natural sands.

Any structure that causes the beach to be lost is not providing beach protection. To ensure

that the beaches can resist climate change, projects need to ensure that the beach remains

intact after the structure is built. Seawalls are unlikely to meet this requirement.

Guideline G3: Coastal protection measures must ensure survival of the beach above

high tide.

In the past, no consideration has been given to visual impacts, human use of the beach or

landscape. This has led to the ―industrialization‖ of India‘s coasts with numerous rock walls

and groynes. Several attractive beaches were lost which decimated the coastal tourism

potential, a high priority economic activity of the coastal states and islands. The fishermen

lost their natural fish landing and net drying environment and so they ultimately clamoured

for more fishing harbours and artificial fish landing centres, leading again to loss of more

beaches downstream. Natural landscape protection is a legacy for future generations. An

example isNavabagh beach, Vengurla, Maharashtra where seawall, vegetation and wide

beach facilitates fishing operations, recreation and tourism. The wall at Navabagh is known

as ―last line of defence‖. It was built a long way inland and will only play a role if a


70

succession of very large and unusual storms erodes the beach. Under most conditions, the

wall doesn‘t interfere with natural processes. Walls placed further seaward have been shown

to cause loss of the beach.

Guideline G4: If sand-based solutions are not possible, constructed structures

should have minimal visual, social and environmental impact. Coastal protection

structures should not obstruct but exist naturally with the esthetics of beaches.

Structures should maintain the natural landscape and ecosystem function of the

coast.

Public access to the beach is a priority, including fishers who need spaces for their boats

and nets. Seawalls will normally fail to meet this guideline.

Guideline G5: Coastal protection structures should not inhibit public access to the

beach.

Reefs provide a very important solution, but they are best when the crest is at least higher

than low tide levels. Many computer model simulations have shown that having the crest at

high tide allows the reef to have low visual impact, while providing substantial protection to

the coast. Lower levels are satisfactory but if the reef was to subside, lose its crest in storms

or lower in any way, the efficacy of the reef can be lost. Thus, to allow for these factors and

for Climate Change, the level of the crest may be best placed at the high tide level, so that

the reef still allows water over the top, but inhibits the waves during the lower tides. Crest

height can be augmented in the future.

Guideline G6: The most appropriate crest height for offshore reefs is high tide level

to ensure that the structure provides protection now and will remain viable with sea

level rise

With rising sea level and larger waves, the crest levels of structures may need to be

elevated. This may be incorporated into the design of the structure now, or an allowance for

future increases can be made in the design. Most structures can accommodate a higher

crest in future.Though the crest level of seawalls also can be raised, they are unable to meet

the demands of climate change.

Guideline G7: Structures should be designed so that crest heights can be increased

as SLR occurs.

Most structures which block transport at the beach will have downstream impacts. While this

may be allowed in the early stages, they cannot continue to do this over the longer term.

There may be exemptions when a very long groyne is designed to create a new sediment

cell after all considerations of downstream impacts have been considered.

Guideline G8: Cross-shore oriented structures (which cross the beach) should block

no more than 60% of the long shore littoral drift in the initial phase after construction

and should allow sand to pass freely after reaching equilibrium.

Seawalls have led to the loss of the beach and numerous downstream impacts in India.

They are not suitable under climate change with larger waves and higher sea levels


71

Guideline G9: Seawalls should be used only as a last resort in cases where major

land infrastructure must be protected or in sheltered waters.

The very hard structures like ports will need to have additional approvals over the softer

solutions. A soft solution will find that the approvals are easier to obtain.

Guideline G10: Methodologies with less than 50 points on the Softness-Index Ladder

will need additional approval by a Central Governing Authority, as well as the

individual States.

Many structures have simply not been compatible with their environment and some have not

been understood well enough. Coastal scientists are well trained in the physical environment

and their training is suited to the functional design of coastal structures, while the engineers

who have not received coastal training can focus on the structural and engineering aspects

and construction methods.

Guideline G11: Beach protection structures should be designed by coastal scientists,

who guide trained engineers, whenever possible, to fit the structure to the local

environment and not limit ecological services.

Zoning of these areas will reduce the number of problems in the future. Once people build

close to the shore, either legally or not, the responsibility to protect them normally comes

back to the Government. It may be very difficult to deal with millions of Climate Change

coastal refugees in the future and so planning now may reduce that problem. We

acknowledge that Hazard Vulnerability zoning is being done by the Government of india and

it can be a handy tool in the site selection for development.

Guideline G12: Development in low-lying areas that are at risk of flooding and

inundation should be avoided to reduce such hazards and risk.

Ports can provide a very positive public facility. For example, jetties that are useful for the

broader community, safe moorings, good beaches etc. The public may not be allowed into

dangerous work areas.

Guideline G13: Ports should be designed to maximize economic and social benefits

that include improvements to public amenity and adjacent beaches, notwithstanding

operational areas.

Many ports in India are inside an estuary but the entrance has been built with little concern

for the sedimentary environment. This has led to major disruptions of beaches and

downstream erosion. Modern shapes which naturally by-pass much of the sand lead to

reduced dredging requirements, a more restricted dredging area to reduce cost and more

easy by-passing using pumping.

Guideline G14: Ports should be designed using modern bypassing shapes, which are

curved with the two breakwaters overlapping. Such ports are easier to manage and

channels can be sustained with a more cost effective bypassing system.

Long straight beaches are a unique environment. The whole beach is one single cell and

any disruption along this beach can have widespread impacts. The most appropriate


72

locations for ports are on beaches bounded by headlands, where the sediment cell is no

longer than 8 km.

Guideline G15: Ports and harbors should not be constructed on long beaches (>8 km

long) with long sediment cells, unless adequate care is taken to enable sand to

bypass. They are best constructed in zones bound by headlands with short sediment

cells, within 4 km on either side.

Urban drainage causes beach pollution and can sweep sand off the beaches during the

monsoons. This sand loss disrupts the beach and numerous drains will cause erosion. The

quality of the beach is also affected by such discharges. The CRZ also insists on treated

drainage and deeper discharge. This needs to be strictly enforced.

Guideline G16: Urban drainage should not terminate at the top of the beach. Pipes

must discharge via existing conduits, via ports or at depths beyond -4 m offshore, i.e.

underwater at depth.

5.4 APPENDICES AND WRIS

To support the Guidelines, much work has been done under the project to provide

quantification of possible changes to key parameters with climate change. Databases have

been established through commissioned research, and located in publically available web-

sites. Computer tools have been developed to use data from these data-sets to assist

design of coastal protection schemes in conjunction with these Guidelines.

The topics covered in the Guidelines are covered in detail in the 17 appendices as follows:

Background to the Guidelines

1. Explaining the Guidelines

2. Indian Coastal Scientific Literature

Regulatory Framework

3. Existing Regulations for the Indian Coastal Zone

4. Strategic Planning of Coastal Zone and Shoreline in India

Coastal Systems

5. Glossary of Coastal Terms

6. Coastal Processes

Interventions for coastal practitioners

7. Sand-based Solutions for Coastal Protection

8. Seawalls

9. Groynes

10. Offshore Reefs and Islands

Project planning

11. Data collection and modeling for coastal protection

12. Environmental Impact Assessment of Coastal Protection

13. Climate Change Projections for Indian coast

14. Using the WRIS Database for Climate Resilient Coastal Protection and Management


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15. Economics and Life-cycle Costing for Coastal Protection Schemes

16. CoastTool for Planning Coastal Protection

17. Documentation and Application of the CRCPM Guidelines

5.5 CONCLUSIONS

Many regulations and policies already exist for the protection and management of the coast

in India. However, most coastal states are recommending shore protection now, i.e. prior to

higher climate change sea levels, more intense and more frequent storms and increases in

population along the coast without always appreciating the instructions provided by CWC or

CRZ. This challenges the practical value of the regulations. Each regulation should aim to

embody an anticipated outcome and, by examining the effectiveness of the existing

regulations and their enforcement, informed decision-making for the future is contextualized.

State governments under appropriate policies can enforce many of the regulatory guidelines

suggested, as they are mostly procedural. For example, changes to reporting standards in

an EIA, or changes to the way a project is assessed, can be achieved within the responsible

departments without legislation. However, a mutual policy is needed that sets the

boundaries, as well as promotes implementation strategies. Other guidelines, such as

building regulations along the shoreline, require legislative approval for enforcement.

However, many of these are already in existence within the current CRZ. While there is

some repetition of existing coastal regulations or instructions for coastal protection the

repetition here is designed to bring all relevant recommendations to one place for

convenience and cross-sectorial understanding.. The CRZ has numerous exemptions, which

are not duplicated here. Such exemptions may be better dealt with when these Guidelines

are ready to become a Regulation.


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Table 5.2 The Environmental Softness Ladder for coastal protection solutions. The higher you go up the ladder, the harder it gets. The Point allocations relate to the leeside and downstream impacts, local impacts and public

amenity. Cost of construction or method of construction and materials are not considered in this table.

Title Methodology Status, including visual and public amenity

benefits Environment

Softness-Index Points

CONSTRUCTION-BASED

Steep seawalls A long shore wall is built to protect the land with front slope gradient >1:15. Very poor Reserved for last resort Best in sheltered waters

0

Low gradient seawalls A long shore wall is built to protect the land with front slope gradient <1:15. Poor Reserved for last resort Best in sheltered waters

5

Headland groynes Groynes longer than 300 m with high crest Poor Not suitable without considerable investigation 5

Long, high-crested groynes

Groynes longer than 100-300 m with crest above high tide Poor Industrial regions 20

Short, high-crested groynes

Groynes with crest above high tide, but less than 100 m long Below average Industrial regions, gaps in seawalls 40

Low-crested groynes Series of groynes with crests lower than high tide, and less than 100 m long Good with wider beach All beaches Best on beaches with net littoral drift

60

Offshore breakwaters A breakwater is built offshore Good, unless close to shore or crest is high and blocking vista

All coasts 60

Nearshore Reef A reef is built shoreward of Chart Datum isobath Excellent if public benefits are included and crest is low

All beaches Best on beaches with net littoral drift

75

Offshore islands An island with public amenity is built offshore Excellent, if the island is not mostly blocking the vista Water sports can be added and marine life

All coasts 85

Offshore reefs Reef is built offshore, normally in 3-8 m depth Excellent Water sports can be added and marine life

All coasts 90

SAND-BASED

Nourishment Major sand replenishment. Sand source is lower beach, offshore or external Excellent Beaches, no buildings on dune May be able to build new dune

95

Dune Restoration Minor sand replacement, from the beach Excellent Beaches, no buildings on beach and dune 100

Dune Care Replanting, fencing, walkways on dunes Excellent Beaches, no buildings on dune 100


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25-27 JULY 2016

6 UTILIZING THE GUIDELINES

6.1 INTRODUCTION

The Climate Change Adaptation Draft Guidelines for Coastal Protection and Management in India provide an easy-to-use method to develop responses to coastal erosion which are primed to deal with climate change impacts. Sound decisions are needed because coast protection expenditure is already large and likely to become a significant fraction of GDP in future in a climate change scenario. The current lack of systematic assessment justifies the need for guidelines requiring greater scientific investigation, computer modelling and sound environmental impact statements.

While investment in coastal structures for the year 2100 is not likely to occur now, at least the methods adopted can be the most appropriate for both current situations and the future. While they may not be specifically designed to deal with future conditions, they need to be amenable to adjustment in the future. Moreover, the designer can be cognizant of the methods that will not be ideal under higher sea levels and larger storms.

6.2 WHAT DETERMINES STRUCTURE SUITABILITY?

Beaches are grossly divided into two types. One is called ―neutral‖ or ―happy‖, whereby the sand simply moves back and forth along the beach within the sediment cell as the seasons change, but there is no large net transport either way when averaged over decades. Such beaches are common between two headlands or in locations where the beach has a wave climate that leads to net zero sediment transport.

The other type of beach is called ―hungry‖. Such beaches are out of alignment with the wave climate. Sand moves up and down the beach in the different seasons, but the net movement when averaged over decades is substantially one way only. These beaches have developed historically in cases where there‘s a supply of sediment from a river at the upstream end. In recent times, many of the rivers have dams or river sand is mined for commercial and construction purposes and so this supply has greatly reduced. Even the beach / dune sand is mined(in violation of the CRZ!) and this has caused severe erosion at many places.

Any change to the supply has consequences. With reduced inputs, the hungry beach will attempt to realign so that net transport approaches zero. As such, one end of the beach will erode and the other will accrete to find a new alignment which has overall net zero sediment transport. In the worst case, the rotation could be hundreds of meters. In the absence of good scientific understanding, any attempt to block this rotation with structures will leave the problem unresolved or even aggravated.

The differentiation between neutral and hungry beaches is fundamentally important when making decisions about coastal structures. Case studies of major blockages due to ports etc. have shown dire consequences for downstream beaches in zones of strong net transport. Thus, neutral beaches are fundamentally more stable than hungry beaches as they don‘t need a large and continuous supply of sediment at the upstream end.

In India, with changed sediment supplies from rivers, it may be assumed that many beaches are currently attempting to rotate, but this is being stopped by human intervention. Thus, all beach works should know the local longshore sediment transport rates and have a primary goal of putting the beach onto a more neutral alignment. This can lead to downstream impacts (whether using reefs, groynes or any other method) because sand deliveries to neighboring zones will reduce. Thus, the primary sediment cell must be considered. However, a neutral beach is much


76

easier to sustain. Beach nourishment within a neutral cell has extremely positive benefits,this lasts for a long time and allows the beaches to be prepared for climate change. The neutral beach may be protected against climate change by adding sufficient sand to deal with SLR. On a hungry beach however, the nourishment will be washed away and will need more regular renewal.

6.3 THE ENVIRONMENTAL SOFTNESS LADDER

Appendices 7-10 of the Guideline documentdiscuss potential interventions which fall into the following two categories:

Sand based solutions

Construction-based solutions

A third option is ‗Planned Retreat‘ (or ―Do Nothing‖) which identifies regions as sacrificial orrelocation of threatened buildings. No relief is provided for erosion, overtopping or flooding. The ‗Do Nothing‘ option is adopted when the processes are natural and cyclic and no population or economic activity is affected. While ‗Planned Retreat‘ has potential for an unmanageable erosional site or under advanced regional planning, it remains outside the bounds of coastal protection. Such decisions are often within the domain of city planners or politicians (arising when unplanned storms arrive!) and are partly addressed in the CRZ. Thus, Planned Retreat is not considered here.

While the terms ―soft‖ and ―hard‖ are used in coastal engineering to describe the ―solution‖ being developed, the definition is sometimes confused by the construction materials being used. To avoid any confusion, the terms are defined here:

Soft coastal solutions are those that do not damage or grossly interfere with the beach, and which allow natural flow of sand along the beaches. Soft solutions might be used to enhance marine ecosystems or public amenity. A soft solution would normally not project above water level around high tide.

Hard coastal solutions are those that disrupt the beach, natural sediment movement and environment. They normally include structures like seawalls, groynes, port walls, wharves, and high breakwaters. They usually have a large visual impact and physical presence.

Soft construction materials are usually sand based. This could include nourishment, sand-filled geocontainers, rubber blocks etc. Notably, a geotube inflated with sand is very solid, but it‘s normally put in the ―soft‖ category.

Hard construction materials are substances like natural rock or concrete. Under these definitions, a soft solution can be constructed from hard materials, e.g. an offshore reef which is made of rocks. Conversely, a hard solution can be made from soft materials, e.g. a seawall or groynes made of geocontainers.

There are many shades between the two extremes of soft and hard, which make it difficult to rank the various coastal protection methods. Here, a scheme is presented to rank the commonly-adopted solutions, called the ―Environmental Softness Ladder‖ (Table 6.1). The metaphor is a gentle reminder that the higher you go up the ladder, the harder it gets. Points are allocated between 0-100 with highest scores for the softest solutions.

To eliminate confusion about reefs, breakwaters and islands, a reef is defined as being underwater at some stage of the tide, i.e. crest level is at or below high tide. A breakwater or island is defined as being out of the water at all times, i.e. crest level above high tide.

6.4 THE SELECTION OF A SUITABLE PROTECTION METHOD

A key tool for the designer is the Environmental Softness Ladder (Table 6.1).Rock seawalls are placed at the top of the Environmental Softness Ladder (i.e. the hardest option) and receive zero points.


77

The common assumption is that the crest level of seawalls can be easily raised to fight storms and SLR. However, our calculations in Appendix 8 of the ‗Draft Guidelines‘ demonstrate that such large units will not be transportable, or potentially not available from the rock quarries or economically not feasible with alternative materials. And so the seawall is not ideal for future climate change as the sea level rises and storm intensity increases. In combination with the environmental impacts, loss of amenity and loss of the beach, the seawall ranks at the bottom of suitable methods for preparation against climate change. Seawalls may be best restricted to port areas, rather than being adopted on beaches for coast protection.

The analysis has shown that existing seawalls should be modified to have gaps some 300 m long every 2 km of coast (Appendix 8 of the Guidelines). The rocks from the existing seawalls could be used to help construct short groynes on either side of the gaps. The gap should have a shorter groyne on the upstream side (e.g. 50 m) and longer on the downstream end (e.g. 100 m). Alternatively, an offshore reef could be constructed on the downstream end of the gap. The reef would have the crest at high tide level and would be about 100 m long (in the longshore direction) and some 100 m offshore of the seawall.

6.5 POINT SYSTEM (CPoints)

The point system, CPoints, for project evaluation establishes the selection criteria and evaluation process for coastal protection projects. This note provides an example of the documents to be completed under the guidelines. There are two parts to the CPoints Form:

(1) Part I : Basic information about the project to be considered, which needs to be filled by the project proponent;

(2) Part II: Checking against compliance with the coastal protection guidelines, to be filled by the approval authority.

The project approval criteria is based on the project proponent‘s written description of the

coastal protection solution recommended, but do not guarantee that the proponent will take on

the project. These criteria are used to screen projects presented to the regulatory authority and

to ensure the coastal protection project‘s compliance with the guidelines. The CPoints provides

a critical tool for determining which solutions are appropriate for the environment. The selection

criteria allow project proponents‘ to understand the policies and priorities for coastal protection.

CPoints also ensures that coastal protection projects are selected based on the government‘s

priorities for sustainable coastal protection methods.

As an example, evaluation of a beach restoration project being implemented at Ubhadanda,

Sindhudurg Dt., Maharashtraas part of the CRCPM Project is presented here(Table 6.2). The

project site (Figure 6.1) is part of a straight coast of length approximately 5 km starting from a

headland and a creek in the north at Dabhoswada (north of Vengurla) and ending at another

headland in the south near Muth. Immediately south of the creek in the north, there is a sand

spit of approximately 200 m length. The coast further south is protected by a bund-cum-road,

about 750 m in length, which protects a densely populated fishing community in the hinterland.

Further towards south the beach width increases and degenerated sand dunes are found at the

backshore. Many tourist resorts are located in the hinterland region. Casuarina plantation is also

seen in the backshore/hinterland region of this sector.

The project site is about I km long south of the bund-cum road in the northern part of the above

coast and belongs to Ubadanda village of the UbadandaGrama Panchayat (GP). In addition to

its use by the fishermen who reside in a colony north of this site, it is also an important tourism

spot.


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Table 6.1 The Environmental Softness Ladder for coastal protection solutions. The higher you go up the ladder, the harder it gets. The point allocations relate to the leeside and downstream impacts, local impacts and public amenity. Cost of construction or method of construction and materials are not considered in this table.

Title Methodology Status, including visual and

public amenity benefits Environment

Softness Index Points

CONSTRUCTION-BASED

Steep seawalls A long shore wall is built to protect the land with front slope gradient >1:15

Very poor Reserved for last resort Best in sheltered waters

0

Low gradient seawalls A long shore wall is built to protect the land with front slope gradient <1:15

Poor Reserved for last resort Best in sheltered waters

5

Headland groynes Groynes longer than 300 m with high crest Poor Not suitable without considerable investigation

5

Long, high-crested groynes Groynes longer than 100-300 m with crest above high tide

Poor Industrial regions 20

Short, high-crested groynes Groynes with crest above high tide, but less than 100 m long

Below average Industrial regions, gaps in seawalls 40

Low-crested groynes Series of groynes with crests lower than high tide, and less than 100 m long

Good with wider beach All beaches; best on beaches with net littoral drift

60

Offshore breakwaters A breakwater is built offshore Good, unless close to shore or crest is high and blocking vista

All coasts 60

Nearshore reef A reef is built shoreward of Chart Datum isobath

Excellent if public benefits are included and crest is low

All beaches; best on beaches with net littoral drift

75

Offshore islands An island with public amenity is built offshore

Excellent, if the island is not mostly blocking the vista; Water sports can be added and marine life

All coasts 85

Offshore reefs Reef is built offshore, normally in 3-8 m depth

Excellent, Water sports can be added and marine life

All coasts 90

SAND BASED

Beach Nourishment Major sand replenishment. Sand source is lower beach, offshore or external

Excellent Beaches, no buildings on dune May be able to build new dune

95

Dune restoration Minor sand replacement, from the beach Excellent Beaches, no buildings on beach and dune

100


79

Dune care Replanting, fencing, walkways on dunes Excellent Beaches, no buildings on dune 100


80

Figure 6.1 The site in Ubadanda village near Vengurla, Sindhudurg district, Maharashtra where the pilot demonstration project involving beach restoration is being implemented as part of the CRCPM Project

Table 6.2 Filled up (just for demonstration purpose) ‘CPoints’ forms for Ubhadanda beach restoration project of CRCPMP

The CPoints forms

Points for Coastal Protection Projects

Part I(To be filled by the project proponent)

A Basic Information

Location Name Ubhadanda

State Maharashtra

District Sindhudurg

Village / Municipality / Corporation Ubhadanda

Beach Name Vengurla

Latitude (decimal degrees) 15.8515

Longitude (decimal degrees) 73.6265


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Engineer in charge Project Director

Project Proponent Project Management Unit (PMU), Maharashtra Maritime Board (MMB) Maharashtra

B Project Description

Sand-based solution*

Dune restoration

Beach/dune nourishment volume (cu m) 16,000

Length of dune /beach to be nourished (m) 1,000

Construction-based solution** Not applicable

Crest elevation of the structure relative to Chart Datum (m) 5.5

Offshore distance of the structure (m) Not applicable

Area of structure (sq. m) Not applicable

Volume of structure (cu m) 10,000

C Project Costs and Economics

Total cost of project (INR) 54,00,000

Whole of life cycle economic costing

Value of threatened coastal infra-structure (INR)

Income generating value of the beach (INR)

Value of downdrift infrastructure (INR)

Total benefit of project (INR)

D Coastal Environment Monsoon Non-monsoon

Length of beach 5,000 5,000

Elevation of dune crest (m) the existing relative to CD 4.5 4.5

Elevation of property behind the dune (m) relative to CD 6 6

Length of coast suffering from erosion (m) 1000 1000

Beach width from dune to high tide line (m) 20 60

Nearest headland (m) 1,000 1,000

Length of sediment cell (m) 5,000 5,000

Beach gradient (ratio) 0.04 0.02

Beach grain size (mm) 0.25 0.2

Typical longshore currents (m/s) 1.5 0.9

Net sediment littoral drift (m3/year) 53,000 m

3/year to the south

to the south Spring tidal range (m) 1.8

Mean Sea Level above CD (m) 1.2

Wave height (m) 2 1

Wave angle to coast (degrees) 20 10

Wave period (s) 8 11

Wave set-up (m) 0.4

Storm surge (m) 0.5

Sea level rise 0.5

Calculations

Calculated maximum water level above CD (m) 3.2

Dune crest elevation above maximum water level (m) 1.3

* For example, dune management, dune restoration, beach nourishment

** For example, offshore reef, offshore islands, nearshore reef, offshore breakwater, low-crested groynes, long high-crested groynes, headland groynes, low gradient seawalls, steep seawalls

Part II (To be filled by the District / State / National Authority)


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E Compliance with Regulatory Guidelines

(All scores are out of 100) Points

Score

Administration

Stakeholder consultation, including government organizations conducted?

100 80

Is consultation with stakeholders effective and the important concerns addressed?

100 50

Is there provision for continuing consultation as the project develops? 100 60

Submission of standard contractual agreement 100 0

Public access to designs, reports and plans 100 0

Sub-total 500 190

Note: Supporting documents for the stakeholder consultations are required. Eg. Meeting notices and minutes, photographs, written submission by the stakeholders

Land Use

CRZ map of the project site submitted 100 100

CRZ category of intervention site (0 pts. for CRZ1, 0 for CRZ 2, 50 for CRZ 3 and 100 for CRZ4)

100 50

Elevation of the new structure from HTL (m) (<2.5 m is 0 pts. and <2.5 m is 100 pts.) 100 100

Is the structure to be built on primary dune (Yes is 0 pts. and No is 100 pts.)

100 0

Is the proposed development/activity likely to be vulnerable to coastal hazards?

100 50

Future development plans within 5 km of the proposed site 100 100

Sub-total 600 400

Note: CRZ map must be prepared by an approved agency. Land use map must be submitted along with the CRZ map. Information about future development plans, e.g. port, jetty, any other coastal infrastructure must be provided

Mining and Dredging (Extractive)

Location of mining/dredging (shoal & channels 100 pts.) 100 100

Location of mined / dredged sand disposal (dune, beach, nearshore 100 pts.)

100 100

Clay silt content of dredged material (<15 % is 100 pts.) 100 100

Sub-total 300 300

Note: Sediment grain size and chemical analysis report must be submitted. All analysis must be done by an ISO certified or accredited laboratory (e.g. National Accreditation Board for Testing and Calibration Laboratories (NABL))

Environmental Impact Assessment

Has Environmental Effects Statement prepared and submitted 100 0

Has a thorough environmental/social impact assessment been completed?

100 0

Is the issue clearly defined? (cause, consequences, spatial extents) 100 70

Field data collection 100 80

Computer modeling 100 0

Have options lower on the Ladder been considered 100 100

Is the option site specific and depending on the local conditions? 100 100

Effectiveness for climate change adaptation 100 100

Any downstream impacts 100 100

Is the monitoring and maintenance strategy clearly defined? 100 60

Is the design reviewed by technical committee and recommendations submitted?

100 0

Sub-total 1100 610


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Note: The ‘Environmental Statement’ (ES) is the report normally produced by, or on behalf of, and at the expense of the proposer which must be submitted with the application. It embraces the first four elements of: (1) gathering environmental information, (2)describing the project, (3)predicting and describing the environmental effects of the project; and (4)defining ways of avoiding, reducing or compensating for the adverse effects.

Ecology

Ecological sensitivity 100 100

Ecological impacts assessment 100 0

No Impact on mangroves 100 100

No Impact on coral reefs 100 100

Sub-total 400 300

Note: The ‘ecological impact assessment must be done by a competent agency, e.g accredited agency for EIA studies or research organizations, universities. Is the site a turtle nesting area or would affect any endangered species, coral reefs or mangroves?

F Compliance with Intervention Guidelines

Coastal Protection Solution

All reasonable options been considered 100 80

Soft or hard solution 100 100

Softness Index 100 100

Plan for nourishment 100 100

Length of beach created 100 100

Beach width 100 100

Minimal downstream impacts 100 100

Minimal obstruction to littoral drift 100 100

Minimal re-nourishment requirement 100 100

Security of beach in storms 100 80

Sub-total 1000 960

Note: At least 3 options must be considered and of which 2 must be soft solutions. Full points are awarded to soft coastal protection options

Safety

Sheltered beach 100 100

Structure friendliness for humans 100 100

Beach gentleness 100 100

Low adverse currents 100 100

No wave over-topping at beach 100 100

Sub-total 500 500

Note: The proposed solution must provide a sheltered beach in all weather conditions. Structure induced currents must be identified and reported.

Community Utility

Permanent activity spaces for the public 100 100

Beach access 100 100

Potential for adding amenity 100 60

No obstruction to beach activities 100 100

Sub-total 400 400

Note: Whether the proposed solution would provide beach space for community, e.g. recreation, boat parking, beach seine. If the solution can add amenity like water sports (surfing, snorkeling, sheltered swimming)? Any obstruction to beach access by visitors, fishers, etc?

Aesthetics

Natural looking beach 100 100


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Good visual Impact 100 100

Construction Impacts 100 80

Low environmental effects during and after construction 100 100

Sub-total 400 380

Note: Whether the proposed solution would affect the natural character of the coastal environment. The impacts during construction could include increased turbidity of the nearshore environment, sound during construction, increased traffic, need to bring heavy machinery and equipment for construction, extended construction period

Climate Change

Adapted to climate change 100 100

Adaptable to climate change 100 100

Sub-total 200 200

Note: Whether the proposed solution is adapted to the projected climate change like sea level rise and increased storms. Can the structure design be easily modified for increased storm conditions?

Hybrids

Bonus points for a multiple solution with nourishment 100

Note: Hybrid solution e.g. offshore reef and beach nourishment

Project Life and Cost Benefit Ratio

Predicted life cycle of project (years) (10 pts. per year up to 100) 100 10

Benefit to cost ratio (> 5: 1, 100 pts.) 100 100

Sub-total 200 110

Note: The cost benefit analysis must consider the social, economic and environmental costs and benefits of the coastal protection options, along with the implications of a base case (or business-as-usual option). The analysis must provide the basis for an analysis to identify those stakeholders who are positively and/or negatively impacted. It should also identify the social impacts of options in terms of local tourism, housing, jobs, population, supporting industries and the long-term viability of the project. The costs must considered the full life cycle cost including construction, maintenance and not just the construction cost or loss of property

6.6 APPROVALS

In defining a project, the Guidelines indicate that all options at lower levels on the Environmental Softness Ladder need to be examined before approval can be granted to a preferred solution which is higher up the ladder. That is, a proponent cannot proceed up the ladder rungs without checking each option during that ascent. This means that projects at the top of the ladder will need considerably more studies and investigations than those at the base. The goal is to:

Encourage the use of the softest possible solutions

Ensure that softer options have been formally ruled out as unsuitable

Weightage: Currently, the ―CPoints‖ form allocates equal weightage to each section and each question. For example, the softness index is only one factor in the full points system, and thereby has a small overall weightage on the outcomes.

This means that issues of safety have the same weighting as issues of environment, for example.One of the key weights is the well-understood trade-off between project cost and environmental impacts. This relationship is now more formalized within the Guidelines by the need to undertake a life-cycle costing that must achieve a benefit/cost ratio exceeding 5:1. A similar requirement has been used for decades in Britain when local bodies are applying for coast protection funding from government.


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„CPoints‟ and CRZ: In the relation to the CRZ zoning of the site in question, discriminating between the different environments is needed (Table 6.3). The CRZ is sub-divided into the following four sub-categories, according to CRZ Notification 2011:

CRZ I: include areas that are ecologically sensitive like mangroves, corals and coral reefs, sand dunes, mudflats, national parks, marine parks, sanctuaries, reserve forests, salt marshes, turtle nesting grounds, etc. A 50m buffer zone around the mangroveswith 1,000 m

2area is also to be considered as CRZ I. CRZ I also include the inter-tidal zone.

CRZ II: include areas that have developed close to the shoreline. These are urban areas, which have drainage, approach roads and other infrastructural facilities with a ratio of built up plots to total plots more than 50 per cent.

CRZ III: are relatively undisturbed areas that are neither CRZ I or II. Area up to 200m from HTL for seafront and 100m for tidal influenced water body is to be set aside as No Development Zone (NDZ).

CRZ IV: include water area from LTL to 12 nautical miles seaward. For tidal influenced water bodies, this includes the water area from the mouth of the water body at the sea upto the influence of tide.

Special areas: These include CRZ areas within municipal limits of Greater Mumbai, CRZ areas of Kerala including backwaters, CRZ area of Goa, critically vulnerable areas like Sunderbans and other ecologically sensitive areas identified under the Environment (Protection) Act, 1986.

There is a special notification called Island Protection Zone Notification, 2011 which governs the islands of Andaman and Nicobar and Lakshadweep. There are about 500 islands in Andaman and Nicobar and about 30 in Lakshadweep. The NDZ for the development of ecotourism activities as per the Island Protection Zone Notification 2011 is 50m from the HTL. (After hazard line demarcation, the hazard line will be considered the no development zone limit). Mining is prohibited by the notification. Developmental activities are carried on these islands based on the plans approved by the Ministry of Environment and Forests (MoEF).

Table 6.3 Maximum points allocated for the different CRZ zones

CRZ Zone Points

I 0

II 100

III 0

IV 50

6.7 DEFINING A SAND BASED PROJECT

When defining a sand based solution (Guidelines Appendix 7), there are three key decisions:

Source: Where will the sand come from?

Sink: Where will it be placed and what are the volumes?

Duration: Will the solution require ongoing maintenance or is it a one-off operation?

In relation to the source, most common options are:

Local repositioning: Sand taken from the lower beach around low tide, normally with heavy machinery or from another site within the same sediment cell

Sand pumping: Sand pumped shoreward from offshore of the breakers

Off-site: Sand is brought from an external source, normally by truck. If CRZ regulations were changed, sand may be brought from offshore to the beaches.


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In relation to the sink, most common options are:

Sand dune: a higher/wider sand dune is created at the top of the beach

Berm: Sand is placed to form a wider berm, i.e. the approximately horizontal zone between the dune and the beach face

Profile: Sand is placed on the beach and/or below Chart Datum to re-nourish the full profile.

The required volumes are normally obtained knowing the current scour situation and the design elevations of the sink relative to required levels.

Coastal protection solutions can be a hybrid with multiple solutions being used at a single beach. Most common examples are:

Structures with nourishment, e.g. proposed for Puducherry City

Gaps in seawalls bounded by short groynes. These give fishermen and the public access to the sea and are a very valuable addition for local communities in India.

Offshore reef with shoreline-attached structures, e.g. Ullal, Karnataka.

The hybrids are treated as separate projects and receive points for each element of the scheme. However, a multi-faceted hybrid may be seen as a more secure option for the future and bonus points may be received. The use of nourishment within a coastal protection scheme will be rewarded by 100 points.


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7 SAND-BASED SOLUTIONS FOR COASTAL PROTECTION

7.1 INTRODUCTION

Most estimates indicate that more than 50% of the Indian coast is eroding. The other 50% is either stable or accreting. The primary cause of much of India‘s coastal erosion is sand deficiency. Anything that affects the supply of sediment to beaches could create erosion. More often than not, the sand deficiency is caused by human activities than natural processes. Seawalls, groins, dredging of navigational channels, trapping of sand with breakwaters, jetties, damming of rivers and sand mining have all contributed to sediment deficiency and thereby increased coastal erosion.

In the past,development of coastal areas often began behind dunes or in back bay areas,which provided substantial buffers between buildings and the sea. However,modern development of beach areas has predominantly occurred in closeproximity to the beachfront and has often resulted in the replacement of dunesystems with buildings, coastal roads or other infrastructure. This practice has increased the exposure of buildings and coastal infrastructure todamage from natural forces. Theexistence of buildings or coastal infrastructure relative to an eroding shoreline results in a reduction inbeach width, adversely impacting both natural storm protection and therecreational quality of affected beaches

Overall there are three available solutions to a local coastal erosion problem: (1) hard solutions, (2) soft or sand-based solutions and (3) retreat.

While a few projects have adopted sand-based solutions in India, the overwhelming preference for coastal protection structures has been seawalls and groynes. None of these shoreprotection structures, however, adds sand to the beach system to compensate for sand deficiency. International best practice has favoured a wider variety of solutions. In this lecture note, the category of―sand-based solutions‖ is considered:

1. Dune Care: nurturing existing or artificial sand dunes, focussing on methods to enhance the dunes by planting and the use of fencing to prevent trampling

2. Nourishment: Introduction of new sand to the beach system

3. By-passing: Sand trapped near a structure or river is moved past the blockage

4. Back-passing: Sand which travels along a beach is moved back to its starting point

While the terms ―soft‖ and ―hard‖ are used in coastal engineering to describe the ―solution‖ being developed, the definition is sometimes confused by the construction materials being used. Soft coastal protection solutions are those that do not damage or grossly interfere with the beach, and which allow natural bypassing of sand, such as nourishment or a submerged offshore reef. Soft solutions might be used to enhance marine eco-systems or public amenity. A soft construction solution would normally not project above water level around high tide. On the other hand, hard coastal solutions are those that disrupt the beach and environment. They normally include structures like seawalls, groynes, port walls, wharves, and high breakwaters. They usually have a large visual impact and physical presence.

In relation to the material being adopted for construction, soft materials could include nourishment, sand-filled geocontainers, rubber blocks etc. Notably, a geotube inflated with sand is very hard, but it‘s normally put in the ―soft‖ construction material category. Hard construction materials are substances like natural rock or concrete.


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7.2 MORPHOLOGY OF THE COAST AND DUNES

The coastal geomorphological zones are depicted in Figure 7.1. From offshore, the sub-tidal beach within the nearshore zone is located in deeper water beyond the surf zone. The surf zone interacts with the sub-aerial beach through the swash zone and onto the berm of the beach. Landwards of the berm, a series of dunes may have formed.

A dune is a mound or ridge of sediment with its axis, or crest, parallel to the shoreline. Many relict dunes in India may have beenestablished by winds and wave over-topping duringperiods of high sealevels. However, in the normal conditions the dunes form when strong winds bring beach sand shorewards from the upper beach and berm (Figure 7.1). Vegetation on the dune helps to capture the wind-blown sand and the dune may grow in volume after each successive wind event.

In principle, the dune/berm combination may erode during severe storm events (Figure 7-1). The sand is moved offshore onto the sub-tidal bar. Once the storm abates, long-crested swell slowly brings the sand back to the beach. Sometimes this process is restricted to the berm only, but sometimes the storm is large enough to engage the dune as well.

Thus, the dune provides two key services. First, the high crest can prevent or reduce over-topping by big waves in storms. Secondly, the dune provides a sediment reservoir which may be re-distributed in large storms,thus reducing further impact of the waves, and subsequently returned to the dune in calm weather.As waves reach a dune and its sediments move and shift, the wave energy is absorbed, protecting landward areas from the full brunt of the storm. But there needs to be enough sediment available in the beach environment to facilitate this.

Dunes in India take on a remarkable range of sizes (evenfrom 0.5m upto 10m in height, the tallest is seen in south Tamil Nadu coast)and shapes, depending on the amount of sand available, the size of the sand, beach width, time available to build and the prevailing wind directions. The beach is the sole source of sand for coastal dunes. Many beaches have a small frontal dune because the winds are not strong enough to bring sufficient sand shoreward.

Dunes naturally migrate landwards under sea level rise (Scottish Natural Heritage, 2000) and so they are an ideal coastal protection solution for Indian beaches under climate change. The landward migration may be halted if enough sand is added to the beach to allow the dunes to grow upwards with sea level rise, using the nourishment sand.


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Figure 7.1Typical features of a dynamic beach system (source: NSW Department of Land and Water Conservation, 2001)

7.3 DUNE CARE

Dune Care involves nurturing existing or artificial sand dunes, focussing on methods to enhance the dunes by planting and the use of fencing to prevent trampling. Dune Care does not involve sand nourishment to create a new or larger dune, although a Dune Care programme is recommended for artificial dunes. The goal is to simply improve the vegetation to create a more stable dune and to revitalise the natural systems that existed before dunes were trampled, built upon or damaged by man in general.Vegetation is vital for survival of dunes, both with respect to the binding of sediment by root systems and in facilitating the build-up of dune sediment by wind. The term 'vegetation', as used here, encompasses all the different plant species that grow from the high waterline to the back of the beach through the dunes.

To prevent the public from damaging the dune, most Dune Care projects use sand fencing around the newly planted area. ―Sand-trapping‖ fences have been used also to trap wind-blown sand or to simply stabilise the existing sand while plants are growing. The fences are usually temporary and bio-degradable, as they may be broken by wind, sand build-up, the public etc. Thus, in most cases, a simpler fence to mark the dune area is preferred. Sand trapping fences should not be placed where a dune of adequate size already exists, where they would trap sand in unnatural configurations, or where they cannot be buried, such as in vegetated portions of the dune or too close to the water. Sand-trapping fences around the first dune ridge function as the core around which the natural dune can evolve (Nordstrom et al. 2000; Grafals-Soto and Nordstrom 2009).Most importantly, the dune project area must be protected from fishing boats, vehicles, pedestrians and grazing animals.

7.4 BEACH NOURISHMENT

The term beach nourishment generally refers to the process of adding sediment, also known as ―beach fill,‖ to a beach and/or dune /nearshore system.The principle being adopted is that the ―beach provides the best form of coastal protection‖. A well-nourished beach will provide protection from storms and keep the whole coast healthy. Indeed, the beaches and dunes have been providing coastal protection since the dawn of time. Nourishment is highly recommended as the best method to deal with future climate change. In some cases, a hybrid solution may be adopted with nourishment plus some structures such as offshore reefs/islands or groynes.

The designer of a nourishment project must deal with three key decisions:

a) Source: Where will the sand come from? b) Sink: Where will it be placed and what are the volumes? c) Durability: How long will the sediment remain on the beach?

In relation to the source, there are four zones that may be nourished. In some cases, the beach is relatively healthy but the dune may be inadequate. Thus, sand may be placed to build-up an existing dune or to create an artificial dune. If the beach is also eroded, then sand may be placed both on the dune and on the beach above the berm. In the third case, the whole dune, beach and underwater profile is nourished. The fourth option involves placement on the offshore bar and allowing the natural wave action to re-distribute the sand and bring it up onto the beach.

We summarise and name these options as:

i. dune nourishment - placing all of the sand as a dune backing the beach,


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ii. dry beach nourishment - using the nourished sand to build a wider and higher berm above the waterline

iii. profile nourishment - distributing the added sand over the entire beach profile, iv. nearshore bar nourishment - placing sand in the shallow offshore as an artificial bar.

The most common options for bringing new sand to the beach are:

i. Sand positioning: Sand taken from the lower beach around low tide, normally with heavy machinery is brought up above the HTL

ii. Sand pumping: Sand pumped shoreward from offshore of the breakers or navigational channels

iii. Off-site: Sand is brought from an external source, normally by truck iv. Sand is by-passed or back-passed (see sections below).

The selected design depends on the location of the source material and the method of delivery to the beach. If the borrow area is on land and the sand is transported by trucks to the beach, placement on the berm or in a dune is generally the most economical. Nourishment is particularly effective in protecting upland development against storm waves. The dry beach method results in an immediate increase in beach width available for recreation. Once the sand is placed on the beach, waves and currents redistribute the material offshore and alongshore until a stable profile configuration is achieved. The nourished beach may take weeks to several months to reach the new equilibrium condition depending on local conditions. During this process, the beach will narrow as sand slumps down underwater and so an allowance for this need to be included in the nourishment design.

The durability of the nourishment will depend primarily on the size of the sediment cell versus the volume of sand to be placed. A small volume in a large cell will ―disappear‖ relatively quickly due to re-distribution within the cell by longshore and cross-shore currents. The best solution is to bring enough sand to re-nourish the entire sediment cell. Notably, sand has not actually disappeared, it has just been distributed more evenly throughout the cell and so any new sand provides some benefit throughout the full sediment cell. The benefit may be small if the cell is large and the new volumes are small.Selection of sand

Nourishment projects require the use of compatible sediments. Sediments that are too fine will erode quickly, reducing project effectiveness. Sediments that are too large may not move and shift as intended and could increase erosion and other problems. Coarse sands will create a steeper beachand this can lead to heavy wave breaking and public safety may be reduced. Consequently, the percentage of sand, gravel, and fines in the selected sediment should match, or be slightly coarser than, the existing beach and dune sediments.

Using sediments with slightly larger grain sizes can provide improved erosion control and storm damage protection. More energy is needed to move this larger material, absorbing wave energy more effectively and eroding less readily. In addition, when a dune is overtopped during a storm, the larger sediments shift landward and provide direct protection from storm waves.

Thus, decisions about the range of sediment sizes should be basedon specific site conditions determined from grain size analyses and the desired level of shoreline protection.

The colour and texture of the sediment for a nourishment project can affect the aesthetics of the site. However, because this impact is temporary and does not interfere with the way the shoreline system functions,colour may be optional. Sediment with high concentrations of heavy mineral appears black when compared to the typical white-to-yellow colour of Indian west and east coast. The colour changes are ephemeral (Prakash and Verghese, 1987).

In relation to texture, some compatible sediment sources contain a percentage of fine silt which can deter recreational beach users. Although the silt naturally blows or washes away


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with time, sediment with lower silt content is preferred. In these cases, many international projects have placed such sediment on the offshore bar, which allows the waves to sort the sands and the fines to wash out. But the temporary mud plume may be considered unsuitable for the site. If the sediment has a high shell content, then it also may be best placed on the offshore bar for natural wave sorting.

7.4.1 Dune Enhancement and Artificial Dunes

An artificial dune is a shoreline protection option where a new mound of compatible sediment is built along in the backshore of the beach. Degraded dunes can be strengthened by increasing their height and stabilityor new artificial dunes can be created. Artificial and nourished dunes, not only increase the direct level of protection to inland areas by acting as a physical buffer, the added sediment from dune projects supports the protective capacity of the entire beach system (i.e., dune, beach, and nearshore area).

7.4.2 Appropriate Locations for Dune Enhancement

Dune projects are appropriate for almost any area with a dry beach at high tide, sufficient space to maintain some dry beach even after the new dune sediments are added to the site and good onshore wind is present to slowly support the dune formation (Figure 7.2). In areas with no beach at high tide, the protection provided by dune projects is relatively short-lived because the added sediments are readily eroded and redistributed to the nearshore by waves, tides and storms. In these situations, increasing the width of the beach through beach nourishment may be a preferred shoreline protection option. For projects on narrow beaches where the seaward part of a dune would be reached by extreme high tides or minor storms, the dune will likely erode quickly and require frequent maintenance to retain the level of protection the project was designed to provide. While sand dunes can provide efficient protection against beach erosion, ―false‖ security from storm waves should not lead to inappropriate coastal development which is constructed too far forward.

Figure 7.2 Beaches and fore dunes (the dunes closest to the sea) are in a constant state of change in response to waves and wind. Upper panel: fore dunes are formed when vegetation traps wind-blown sand. Middle panel: the front face of a fore dune is eroded when storm waves crash onto the dunes and wash away plants and sand. Lower panel: the dunes


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form again as vegetation is re-established on an exposed site and begins to trap sand (source: www.teara.govt.nz)

7.4.3 Dune Dimension and Slope

The height, length, and width of a dune relative to the size of the predicted storm waves and storm surge determines the level of protection the dune can provide. The recommended size for an artificial or nourished dune will depend on the desired level of protection, the predicted wave conditions and storm surge for the area, and site constraints (such as beach width and proximity to sensitive resource areas). In general, the dune crest should be at least 3 m above the local HTL. This would need to be larger in cyclone prone regions.

The slope selected for the project will be based on the existing beach and dune slope, the width of the dry beach, and the grain size of the dune sediments. Steep dunes are unstable and may erode rapidly and cause problematic scarps. To avoid this problem, the seaward slope of the dune should be less than 3:1 (base:height).

Figure 7.3 Majali, Karnataka dune design

7.4.4 Volume of Material

The volume of sediment needed for a dune project can be determined by finding the difference in volume between the final design against the natural beach profiles measured on the site. Volumes are normally expressed as m3/m of beach length.

7.4.5 Maintenance Requirements

To maintain the dunes as an effective physical buffer, detailed studies will determine if sediment must be added regularly to keep the dune‘s height, width, and volume at appropriate levels. Dunes may also degrade if the public is given access to the dune or if a Dune Care programme is not put in place. As with most aspects of natural resource management, follow-up management is critical to ensure the success of a dune project.

The amount and frequency of sediment nourishment for a dune project will therefore depend on the proximity of the dune to the reach of high tide, the frequency and severity of storms, the initial design of the dune (e.g., grain size, volume, height, and slope), and how established is the vegetation. Storm wave uprush may eliminate the seaward portion of the dune and create an erosional scarp, but post-storm beach accretion creates a new source of sand to be brought back to the beach, re-establishing the dune sediment budget. Plants may need to be replaced (at the appropriate time of year) if they are removed by storms or die.Losses are more common in the early stages of a planting scheme.As the volumes involved in a dune project are relatively low, some projects will use monitoring to determine

http://www.teara.govt.nz/


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the re-nourishment requirements. However, this can lead to failures of the project if an allowance for re-nourishment is not made early and funds procured.

7.4.6 Planting and Management of Vegetation on Dunes

Each dune site must be considered independently, with approaches tailored to the specific site. Planting shall imitate the natural conditions and should be undertaken after long term monitoring the beach-dune system and near-shore coastal processes and after ensuring that a reasonable physical and natural environment has been established. Post planting monitoring should be undertaken at least bi-annually to assess the beach-dune evolution and the success of the vegetation plan.

The vegetation plan (Figure 7.4)should be developed after a thorough evaluation of the site and observing a natural model or referencing to an adjacent reference area during different seasons. The vegetation plan shall specify the species, spacing, diversity and density. Involving the local community and the local expertise of the community living in the area and agencies working is essential in the site assessment, development of vegetation plan, nursery development, planting, protection, monitoring and management and trading of the produce if any would be appropriate. Trainings related to each and every aspect of ecosystem restoration should be provided to the community, NGO‘s and other stakeholders.

Figure 7.4General distribution of vegetation on the coastal sand dunes in India; Illustration: DeivaOswin Stanley

Dune assessment establishes a baseline so that changes in vegetation cover and species composition can be monitored over time. The restored dune and beach sand need to be sustainably managed by regular monitoring procedures decided specific to the site. „Community Dune Care groups‟ may undertake monitoring of dune condition and vegetation cover periodically.

7.4.7 Project Costs

In general, the greater the quantity of sediment that is used in the project, the greater the construction costs, the lower the maintenance costs, and the greater the level of protection


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provided for the site. The considerations that most influence the cost of dune projects are the severity of erosion, the width and elevation of the beach, the volume and availability of sediment source, the size and location of the proposed dune. For comparison with other coastal protection options (e.g. for seawall, INR 5 -10 crores per km), dune projects typically have relatively low construction (INR 0.25 – 1 crore per km), depending on the sand availability and maintenance costs.

7.4.8 Community Consultation and Participation

Unlike the hard options, the dune project once established can be more easily managed by the local community with some amount of technical guidance(Figure 7.5). Strong community and local government (e.g Panchayat) interest and involvement can generate a sense of local ownership that is invaluable in successfully completing and maintaining a dune project. It is especially important to have local residents on side. To this end, dune restoration or nourishment planning must address the needs and expectations of all users, including local residents, fishers and visitors.

Both existing users of the site and potential stakeholders need to be identified and their views respected. The earlier this occurs the more likely the project will attract sustained community support. Ideally, efforts will extend beyond basic consultation to having users help formulate and implement the project plan. The success of these efforts relies upon an effective community consultation exercise.

In the case of recreational beaches, visitor needs and expectations should also be understood. Their expectations in terms of access and facilities and the recreational experiences that they are seeking may also differ from those of local residents. In short, any dune management project should include a carefully planned procedure to achieve and maintain strong awareness and support within the broader community.

7.4.9 Project Monitoring and Evaluation

Monitoring and maintaining a dune site may be needed for several years after completion of site works. Monitoring is important in assessing (1) whether dune restoration/ nourishment goals have been achieved, (2) what kind of follow-up actions are required and (3) how plans can be modified to achieve better future projects.

Evaluations should be conducted for several years after dune building begins, so that stakeholders can appreciate the coastal protection benefits, the time required for a resilient species-appropriate vegetation cover to become established and have realistic expectations of dune restoration outcomes.

7.5 BEACH PROFILE NOURISHMENT

Profile nourishment involves placing the sand across the entire beach cross-section, both above and below water (Figure 7.5). Because the equilibrium condition develops immediately, there is little offshore redistribution of sand and changes in the dry beach width are minimal. However, this placement scheme is more difficult and also provides less storm protection because there is no extra reserve of sand on the beach as there is with the dune and dry beach nourishment schemes. We recommend that profile nourishment should be accompanied by artificial dune creation.

While the profile is adjusting to reach an equilibrium condition, the general public may perceive the narrowing of the initial dry beach width as a sign of failure of the project. Therefore, public education at the onset of the project is beneficial so that the public understands that some initial alongshore and offshore sediment movement and erosion of the berm are expected. Also, the public needs to recognise that the sand remains in the


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littoral zone within the envelope of beach profile changes, the sand has not actually been "lost‖. Although the profile adjustment will in most cases result in shoreline recession, the material will be still present in the active beach profile; much of it will be in the offshore bar and on the berm.

Figure 7.5 Schematic representation dry beach nourishment (Source: USACE, 1992)

7.5.1 Beach Nourishment Design

The designed beach profile should approximate the natural beach. There are three commonly-adopted methods, i.e. (1) by surveying a nearby healthy beach to find the profile (2) by applying the Dean formula or (3) seaward transfer of the existing beach profile to achieve the required beach width.

Healthy beach profile method: In order to estimate the natural profile, the firstapproach is to study nearby existing contiguous beaches which are not eroding. For this, detailed bathymetric survey(s) are needed on the eroding beach and the nearby beach. The difference in the profiles can be used to find the required nourishment volumes. The surveys should include the dune (or permanent or hard structure on the landward end) out to the depth of closure (the seaward limit of significant sediment movement). Offshore bathymetry data beyond the depth of closure may be required for wave transformation modelling and/or identification of offshore sand source for beach nourishment, but is not normally considered when calculating nourishment volumes.

An example is shown in Figure 7.6 where the healthy and eroding profiles have been surveyed and compared. Notably, the healthy profile has a concave up shape, while the eroding profile is concave down, but both profiles meet at the depth of closure around 6 m depth. The volume required to restore the profile was 350 m3/m of beach.


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Figure 7.6 Measured cross-shore profiles on the eroding coast in front of a rock wall and further south on a healthy natural beach (Puducherry).

Dean method: Dean (1991) developed a method for beach nourishment design based on the equilibrium beach profile model, whereby volumes of fill would be estimated by comparing the equilibrium profile of the borrow material with that of the native material. The relationship for the equilibrium profile given in Dean (1991) is:

y(x) =A x 2/3

where y is the depth in meters at a distance of x meters offshore. The parameter A is a scale parameter that depends on the sediment grain size. A can be expressed (Dean, 1991) as:

where D is the sediment grain size in mm. The Dean profile is concave down (Figure 7.7).

The use of the Dean (2002) concept also provides a direct method for estimating nourishment quantities for various wave and sand-source conditions. Dean‘s method is based on assuming that both natural and nourished beach profiles conform to the characteristic parabolic equation given above. These concepts are generally accepted in the industry.

Depending on the relative values of the coefficient A for the native and beach fill material, the nourished profile will intersect the native profile either landward or seaward of the closure depth(hc) (Hallermeier, 1978) depending on the relative slopes and the amount of dry beach width(Bd) that is being reclaimed(Figure 7.7).

Profile intersection occurs when:

(

)

(

)

Where An and Ab are the native and borrow sand scale parameter. For an intersecting

profile, the fill material sediment grain size, Db> native sediment grain size Dnand therefore,

Ab>An . Conversely, for a non-intersecting profile, the fill material sediment grain size, Db <

native sediment grain size Dn and therefore, Ab< An.

Therefore for an intersecting profile, the volume of beach material per metre length of beach required to create an increased dry beach width is:


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( (

)

)

And for a non-intersecting profile:

((

)

(

)

)

(

)

The equilibrium profile methods do not account for a sediment deficit in the pre-project beach profile, which is common along eroded shorelines where beach nourishment projects are typically considered. This means that surveys of the profiles are essential. The methods also only account for volume below the berm elevation. Volume contained in the dune and upper beach must be added to the estimate. These methods are recommended for quick calculations, and to compliment calculations based on differences between the natural stable beach profile with the eroding profile.

Figure 7.7Intersecting and non-intersecting profiles as suggested by Dean (1991).

Beach width method: On sandy beaches the design profile maybe obtained by simply shifting the existing profile seaward. The existing beach is transferred seaward by the amount of beach widening that is required. Some care needs to be taken to ensure the new profile joins at depth with the existing profile and this is normally done by applying a Dean shape to the seabed.

7.5.2 Design versus Construction Profiles

The design profile is the cross-section that the equilibrated beach is expected to take after equilibrium is reached. The design profile may be calculated using computer models or by comparison with nearby beaches.

The construction profile is the cross-section that the contractor is required to achieve. Normally, the constructed beach contains enough sediment so that the design profile can be achieved after adjustment. In addition, the construction profile may be simpler and easier to build than the design shape for convenience and cost. Both the design fill and the advanced fill quantities are normally included.


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The construction cross-section is usually significantly wider than the design profile because of the steeper slopes and t‘s often steeper than the design cross-section because of budget limitations. Sandcan be placed high on the beach and to allow the wave and current action to adjust the construction cross-section to a flatter equilibrium slope; this usually occurs within the first few months to a year. Residents need to understand that the sand is not lost; the sand is simply slumping down underwater to fill the scoured profile.

7.5.3 Nearshore Bar Nourishment

Nearshore bar nourishment involves the placement of beach fill material in a sand bar just offshore of the surf zone. To be successful, the placement must be within the active portion of the beach profile, typically around half the closure depth. The guidelines suggest that sand must be placed in depths less than 5 m, but this depth may be less in locations with small waves. The appropriate depth is less than 2.5 times the significant wave height averaged over the non-monsoon period (up to a maximum of 5 m).

The bar is dynamically connected to the beach, and so waves will bring the sand shoreward. It is always preferable to do bar nourishment at the start of the non-monsoon when long period waves are present to bring the sand inshore.

Figure 7.8The construction template (source: USACE 1992)

Nearshore bar nourishment is most likely to occur when sand is dredged, e.g. port channels or offshore sources.

7.5.4 Sources of Sand for the Beach Nourishment

The source of sand is one of the critical elements of beach nourishment design. The quality of the sand controls the aesthetics, the cost, and the physical and ecological performance. As noted above, the perfect sand for beach nourishment would be sand that is exactly same or slightly coarser than the native beach sand. The match should include grain size and distribution. However in practice, the choice of material for a nourishment project may be controlled by availability and cost, with only an application of the ―rule of thumb‖ that the median diameter of the borrowed material be equal to or somewhat coarser than the median diameter of the native sediment on the beach (Komar, 1998).

Dredged sand from harbours and inlets can be a sediment source if the dredged sand is uncontaminated and has a small fraction of fine grain sizes (such as silt and clay). In many cases, dredged sand originally came from the beach and should be returned, rather than deposited in the deep water offshore (or on land) where it is permanently lost from the littoral


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zone. If the sand is muddy, then it may be deposited offshore on the bar, which allows the waves and currents to winnow out the muds, leaving the pure beach sand. However, the mud plume may be environmentally damaging in some locations.

Offshore sand deposits are another major source of sand for beach nourishment. Sand from these relict deposits is typically dredged and placed on the dry beach. The primary advantages of this approach includes low cost, high placement rates on the receiving beach, and minimal disturbance onshore while the project is underway

In some beach nourishment projects, ebb-tidal shoals have been mined as they are usually clean sands with grain sizes that match the beach sands. However, we need to be very careful when mining ebb tidal shoals for beach nourishment as these shoals usually shelter and feed the nearby beaches. Changing the natural shoal shape can lead to beach erosion. Indeed, this sand is normally transported out of the estuary naturally during high rainfall events, unless the estuary has been modified internally with deeper channels.

The sediment trapped behind the dams represents another source of sand for beach nourishment. The loss of sediment reaching the coast due to the damming of rivers is a well-documented phenomenon (Willis and Griggs, 2003). The use of this sediment accomplishes two objectives: re-establishment of the reservoir capacity and nourishment of the beaches.

7.5.5 Length of Beach to be Nourished

Nourishment projects should fill the whole sediment cell, if possible, due to alongshore spreading (Komar, 1998, Douglass, 2006). If a short section of beach is nourished, the sand will simply disperse through the whole sediment cell. The rate of alongshore spreading of the placed sand is a dominant engineering measure of the success of a project and is fundamental to determining success relative to economic measures as well. Numerical models are available for detailed analysis of the longshore dispersion of nourished sand placed on the beach.

7.5.6 Transport of Borrow Sediment to the Nourishment Site

Generally, there are two methods of transport and placement of borrow material for a beach nourishment: hydraulic and dry methods. Hydraulic methods are generally used for material obtained from marine-based sources and dry methods for material obtained from land-based sources though the hydraulic method may be employed for land based sources, depending on the site conditions. If the borrow sand is stockpiled on land, the sand is trucked to the nourishment site and placement on the dry beach is obviously the most economical and efficient method. The sand delivered to the shore then needs to be groomed using earth moving equipment to the desired construction profile.

7.5.7 Monitoring

Following construction, the beach nourishment needs to be monitored to evaluate the project performance and to regularly assess the condition of the nourishment. These include shoreline and berm positions, total volume, and the response of the beach to a storm. Beach profile surveys, beach sediment sampling, shoreline surveys, satellite imageries, and wave and water level monitoring would provide an accurate and objective measure of the nourishment project‘s response. Without physical monitoring data, it is difficult to estimate how well the project is performing in comparison to the design. Most monitoring programs involve an early phase of more intensive data collection of beach profiles, sediment and marine ecology to evaluate project performance. After the project performance is established, data collection may be scaled back. A full pre-project (baseline) bathymetric survey should be undertaken, followed by a post-nourishment survey. Surveys are then performed twice a year, typically at the end of monsoon (September for the west coast of


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India) and summer (February or March) to determine the full excursion of seasonal changes in the subaerial beach width and volume.

7.5.8 Re-Nourishment Requirements

In general, maintenance requirements for a nourishment project can be determined by calculating the sediment deficit in the full sediment cell. This is then compared to the volume of sand being placed on the beach to determine the percent effectiveness of the nourishment project. If the percentage is low, then the designer must determine the durability of the nourishment at the local site using computer modelling and assess the value of the project accordingly.

Waves and currents will redistribute the nourished sand in the alongshore and cross-shore directions and extreme storm events may cause losses of sediment from the dry beach if the original volumes were too small. Indeed, larger initial volumes always lead to reduced re-nourishment requirements.

Nourished beaches typically require periodic re-nourishment, until the full sediment cell is filled. Beaches with small net sediment transport or short sediment cells are the most durable. Remember that sand is not being lost from the sediment cell and so each renourishment helps to bring the full sediment cell back to a healthy state. This will occur faster if the initial project spreads sand over more of the full cell.

Beach nourishment projects world-wide suggest that typical re-nourishment intervals range between two and ten years. However, if the weather conditions following the nourishment are generally stormier than average conditions, the time for renourishment may be shorter than the expected 10 years. To lower the risk of a shortened renourishment interval, increased advanced-fill quantities beyond those actually required is an option if sufficient quantity of sand is available. Sand retention devices may be used to prolong the effectiveness of beach nourishment

7.5.9 Relative Benefits and Impacts Compared to Other Options

The major benefit of nourishment projects is that unlike seawalls or other ―hard‖ coastal protection structures, dunes and beaches dissipate wave energy during storm conditions rather than reflecting waves. The design of a hard structure affects how much wave energy is reflected; for example vertical walls reflect more wave energy than sloping rock revetments. These reflected waves erode beaches in front of and next to a hard structure, eventually undermining and reducing the effectiveness of the structure and leading to expensive maintenance. This erosion also results in a loss of dry beach at high tide, reducing the beach‘s value for storm damage protection, recreation, and habitat. Hard structures also impede the natural flow of sand, which can cause erosion in downstream areas of the beach system. Dune projects, however, increase protection to landward areas while allowing the system‘s natural process of erosion and accretion to continue. In addition, because of their more natural appearance, dunes can be more aesthetically pleasing than hard structures (Figure 7.9).

In general, the impacts of nourishment projects are relatively minor when compared to hard structures and ultimately, the replacement of sand on the beaches will lead to stability in the future under climate change.


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Figure 7.9 Well-formed sand dunes in Karnataka and Tamil Nadu

7.6 BY-PASSING

Sand bypassing is the practice of transporting accumulated sand from the up-coast side of a sediment barrier. The construction of breakwaters and other shore normal structures can interrupt the longshore sediment transport and cause erosion of the downdrift coast. Sediment bypassing involves moving sediments from the areas of accumulation to the eroding area, e.g. across a port or entrance training walls. By maintaining the supply of sediment along the shore, sediment bypassing ensures that excessive downdrift erosion is avoided by nourishing the downdrift beaches.

Sand bypassing redistributes sand within the littoral system. This method does not represent a true source of sand because no new material is added to the system. Sediment bypassing associated with dredging operations at the entrance to ports (e.g. Visakhapatanam, India,) and inlets (e.g. Tweed River, Australia, proved to be an effective means of nourishing downdrift beaches. However, sand bypassing has been rarely utilized in India, except at Visakhapatanam Port (and at Pondicherry for a short period), although there are many coasts where bypassing is needed.

Bypassing is sustainable and makes best use of material already in the littoral system as well as reducing un-wanted build-up. In the case of properly designed port breakwaters, bypassing also reduces deposition of material in navigation channels. Methods used to undertake bypassing include the installation of specially designed fixed plant, floating plant (dredgers) or land based equipment.

Sand bypassing considerations include: determination of the amount of sand actually in transport along shorelines and plant capacity - the hourly rate at which a plant can transfer arriving sand.

Many of Indian beaches have already been damaged unknowingly by interrupting the movement of sand along and to the coast. In addition, a large quantity of sand has been removed from the ship channels and dumped offshore or on land. Much of the man-made erosion can be stopped or at least minimised with sand bypassing methods – restoring the movement of sand along the beach past a structure.

7.7 BACK-PASSING

Sand back-passing involves the mechanical transport of material from a wide stable beach to an up-coast sediment-starved beach within a sediment cell. In effect, currents bring the sand, while pumps return it upstream. This method often is utilised in locations where the sand from an eroding reach moves alongshore and is deposited in a more sheltered area. Back-passing essentially ―recycles‖ the sand back to the eroding beach and allows artificial adjustment to seasonal effects.


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Figure 7.10 Sand back-passing, Noosa, Australia

Like sand bypassing, back-passing operations (Figure 7.10)redistribute sand within the littoral system and this method does not represent a true source of sand because no new material is added to the system. Sand back-passing has been rarely utilized in India. Sand back-passing is sustainable and makes best use of material already in the littoral system or onshore.

Considerations for sand back-passing include: ownership of the sediment source, beach uses, littoral drift patterns, environmental effects, would the removal of sediment from the accumulated area cause erosion at the site from which sand is being recycled. As the source sand for back-passing is from the same sediment cell, comparatively low environmental effects are likely, and thereby ecological or visual effects are also minimal.

Stakeholder consultation is essential as removal of sand may conflict with the aims of other stakeholders. If the sand volumes are moderate and the haul distances are short, the back-passing can provide a cost-effective method for beach maintenance. However, back-passing may be less efficient on wide sandy beaches, where large sand volumes will be required.

7.8 SELECTING A METHOD FOR INDIA

Ultimately, the selection of the best method will depend on the field and computer studies which identify the causes of the problem. The most common cause of erosion in India is the imposition of structures causing downstream sediment deficiencies, or the reduction of sand on the beaches due to dredging and mining. In these cases, new sand must be added to the beach or the cause must be eliminated. Even so, the lost sand may still need to be replaced to widen the beach and allow space for the natural processes to become re-established.

In many cases, the cause is just degradation of the dune, public trampling and general slumping of the upper beach. Dune Care involves nurturing the dune with planting and stopping the public from damaging the dune. It doesn‘t involve the placement of new sand. However, there are many cases where the degradation of the dune leads to enhanced erosion. And conversely, the rehabilitation of the dune has led to stability of beaches that were formerly eroding. Potential Dune Care sites should be identified in the CMP‘s of each state as it‘s an inexpensive method to adopt with community participation.

Dune Care will not protect a coastline which is eroding due to sediment starvation from upstream. The erosion will simply cut through the dune and the beach will be lost as seen at Thalapaddy, Karnataka. The root cause of the erosion at Thalapaddy needs to be overcome, rather than relying on the dune.


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Nourishment will be successful in cases when the cause of the sediment deficiency is cured (e.g. by-passing of sediment is initiated past a disruptive port). However, nourishment is also highly effective when the full sediment cell is treated or when the net longshore transport rates are small. Critics may claim that nourishment has ―disappeared‖ but they may not realise that some of the sand has slumped underwater to re-create the sub-aerial profile. In other cases, the sand may be lost longshore due to strong longshore drift. The designer must be aware of the size of the sediment cell, the sediment deficiency in the full cell, the longshore transport rates and the causes of the erosion.

If studies are carefully done, nourishment is expected to help most beaches in India if the amount of sand added is sufficient to sustain the full sediment cell, either in the first nourishment or with a systematic re-nourishment programme that eventually fills the sediment cell. Nourishment projects will only fail if insufficient sand is added or the designer is unaware of the sediment.. As noted already, nourishment is less viable if sand upstream is being blocked by a structure, without being by-passed, on a beach with strong net longshore transport.

In long sediment cells, structures may be needed to sub-divide the cell. However, these structures will not solve the problem in many cases if they rely on capture of natural sand supplies and they may have a substantial impact downstream. Most structure projects in India, particularly groynes and offshore reefs/islands, need to be accompanied by a nourishment programme.

7.9 CONCLUSIONS

Sand-based solutions have the least environmental impact. They acknowledge that the ―best form of coastal protection, is the beach‖. Sand losses due to mining and the impacts of coastal structures have led to sand shortages on many Indian beaches. The sand-based solutions with nourishment overcome these deficiencies and bring the beach back to a healthy state.

Nourishment will typically fill the full sediment cell. Design volumes must allow for sand re-distribution both offshore underwater and beyond the nourishment site. In the long-term, this sand is not lost, and it will protect the full sediment cell.

References

Black, K., 1999. Designing the shape of the Gold Coast Reef: sediment dynamics. Proceedings of the Coasts & Ports ‘99 Conference, 14-16 April 1999, Perth, Australia

Dean, R.G., 1991. ―Equilibrium beach, profiles: Characteristics- and applications,‖ Journal of Coastal Research 7(1), 53-84.

Dean, R.G., 2002. Beach Nourishment; Theory and Practice. Advanced Series on Ocean Engineering – Vol. 18, World Scientific, Singapore.

Dinesh, A.C, Praveen Kumar.P., Shareef.N.M. andJayaprakash.C., 2014. Marine Sand Resources off Kerala Coast vis-à-vis Acute Shortage of Construction Sand in the State of Kerala. Technical paper presented at the conf. on ―Mineral Resources of Kerala‘, Department of Geology, University of Kerala, Trivandrum, India, March 2014

Douglass, S.L., 2006. Saving America‘s Beaches: the Causes of and Solutions to Beach Erosion.Advanced Series on Ocean Engineering – Volume 19.World Scientific Publishing Co. Pte.Ltd. 91p.

Grafals-Soto, R. and Nordstrom, K.F., 2009. Sand fences in the coastal zone: intended and unintended effects. Environ Manag. 44:420-429


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Hallermeier, R. J. (1978). Uses for a calculated limit depth to beach erosion.Proceedings, 16th Coastal Engineering Conference, American Society of Civil Engineers, 1493- 15 12.

Komar, P.D., 1998. Beach Processes and Sedimentation (2nd ed.). Prentice-Hall, Inc. 544p.

Nordstrom K.F., Lampe, R, Vandemark, L.M., 2000. Re-establishing naturally functioning dunes on developed coasts. Environ. Management 25(1):37-51.

NSW Department of Land and Water Conservation, 2001.Coastal Dune Management: A Manual of Coastal Dune Management and Rehabilitation Techniques, Coastal Unit, DLWC, Newcastle

Prakash, T.N. and Verghese, P.A.,1987. Seasonal beach changes along Quilon district coast, Kerala, Journal of Geological Society of India, 29(4), 390-398.

Scottish Natural Heritage, 2000. A guide to managing coastal erosion in beach/dune systems (http://www.snh.org.uk/publications/on-line/heritagemanagement/erosion/ appendix_2. shtml )

Sukumaran, P.V., Unnikrishnan, E., Gangadharan, A.V., Zaheer, B., Abdulla, N.M., Kumaran, K., Ramachandran, K.V., Hegde, S.V., Maran, N., Bhat, K.K., Rao, M.K., Dinesh, A.C., Jayaprakash, C., Praveen Kumar, P., Shareef, N.M. and Gopalan, C.V., 2010. Marine sand resources in the south-west continental shelf of India. Indian Journal of Geo-Marine Sciences, Vol. 39(4), December 2010, pp. 572-578.

USACE, 1992. Coastal Engineering Manual, Manual 1110-2-1100, US Army Corp of Engineers, 2002 – 2006

Willis, CM. and Griggs, GB., 2003. Reductions in fluvial sediment discharge by coastal dams in California and implications for beach sustainability, J. of Geology, 111 167-182.

http://www.snh.org.uk/publications/on-line/heritagemanagement/


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25-27 JULY 2016

8 STRUCTURAL SOLUTIONS FOR COSTAL PROTECTION

8.1 INTRODUCTION

Among the hard and soft measures for the protection of the coast, the structural solutions like

seawalls, groynes, port walls, wharves and high breakwaters are in hard category. Hard coastal

solutions disrupt the beach, natural sediment movement and environment. They usually have a large

visual impact and physical presence.

Adaptation to climate change effects need to be considered for both existing and new structures.

While doing this, conflicting aspects of sustainability and safety need to be weighed against

uncertainty of future climate change effects and higher cost. Possible ways of optimizing while

designing these structures for coastal protection in the above scenario is a real challenge to the

coastal engineers.

Current coastal protection measures in India sometimes result from emergency responses to a

hazard event, which may lead to ad hoc approaches creating unplanned coastal protection of varying

quality. These approaches may not demonstrate the required strategic approach to the

management of the coastline. Innovative methods to protect coasts continue to evolve, but the best

technical solutions may not be seen as cost effective or the politically most acceptable. Furthermore,

coastal protection measures deal with many competing factors around resource sharing. There is a

need for effective and strategic decision-making to limit climate change impacts to the coastline

through a strategic approach.

Today’s methods provide an essential initial basis for such decisions. If the current methods do not

solve the existing problems, then they will fail when confronting larger storms, higher water levels,

increases in population, shortage of sand supply to the beaches and a myriad of other factors. Other

more successful methods may need enhancement to be effective in the future. This means that

great care has to be taken (1) to find the best shoreline protection methods being adopted now and

(2) to thoroughly crosscheck that these will succeed in the face of climate change projections.

8.2 SEAWALLS

Seawall or revetment is the most accepted means of coastal protection in India. The overwhelming

preference for coastal protection structures in India has been seawalls and groynes, while

international best practice has favoreda wider variety of soft and hard solutions.

8. 2. 1 ENGINEERING DESIGN OF SEAWALLS

The “Technical Memorandum on Guidelines for Design Construction of Seawalls” (Kudale and Sarma,

2010) was prepared by the Central Water and Power Research Station (CWPRS), Pune. The basic

design and construction methods are generally available in coastal engineering books and manuals.

However, this Memorandum provides the essential guidelines for Indian practice, with the


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precautions to be taken during design and construction of seawalls. These guidelines are based on

the vast experience of CWPRS in India, both in practice and in the laboratory at Pune. The

Memorandum begins with a list of the various methods of shore protection and highlights design

considerations. The usual steps needed to design an adequate and efficient rubble mound

seawall/revetments are listed. Deviations in design and construction may occur, such as position of

seawall, under-design of armors, toe protection, inadequate or no-provision of filters, overtopping

due to underestimation of design wave or the maximum water level, rounded stones, weak pockets,

discontinuities in sea wall, armor in single layer and/or pitched. These are dealt with in detail.

Finally, the planning of a construction program and maintenance of coastal structures are treated.

The Technical Memorandum does not consider the decision-making in relation to selection of a rock

seawall as the preferred coastal protection solution.

8. 2. 2 EFFECTIVENESS AND IMPACTS OF SEAWALLS IN INDIA

Globally, rock seawalls have been highly successful for protecting the land but the beach is often

lost. This occurs because the slope of the wall is greater than the natural gradient of the beach.

Wave breaking and turbulence at the foot of the wall creates more turbulence, which tends to

suspend the sand and allow currents to carry it away. This results in a steeper nearshore seabed

profile, which subsequently allows larger waves to reach the structure. Furthermore, the reflection

of waves from the wall disrupts the natural processes that bring sand from the offshore sand bar to

the beach during conditions of low swell. The asymmetry of the wave orbital motion under swell has

been shown to carry sand shoreward at these times, but the reflected waves cancel out some of the

onshore net movement. Overall, the walls have been proven throughout India and internationally to

cause the beach to be lost (see examples from Puducherry, Karnataka, Kerala and New Zealand in

Figure 8.1(a-d).

However, seawalls in India remain the most common coastal protection structure. For example, in

Kerala there’s already 350 km of rock seawall and seawalls have been built in most coastal states in

India. The seawall is relatively inexpensive and easy to construct and they protect land-based

infrastructure. They are commonly called “Coastal Protection” structures, but they are more

correctlycalled “Land Protection” structures.

(a) (b)


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Figure 8.0 The beach is lost in front of the rock walls at (a) Puducherry (b) Ullal, Karnataka, (c) Kovalam, Kerala and (d) Dunedin, New Zealand.

Often the wall is built once houses and infrastructure are threatened. By this time, the structures are

well forward on the beach, and so there is usually very little space for the proper location of the

wall. Thus the wall is normally built on top of the beach itself. When the wall is too far to seaward,

all case studies in India have shown that the beach is lost in front and the wall doesn’t stop the

erosion; instead it continues underwater. Many scientific and practical engineering publications have

shown this to occur. Rock seawalls are heavily restricted in many parts of the world, including NSW,

Australia because they don’t deal with the cause of erosion, they cause beaches to be lost and they

produce end-effects whereby scour occurs not only on the front but also at the ends of the walls

(Figure 8.2).

8. 2. 3 Limits to Adaptation for Seawalls

Potential adaptations to climate change have physical, economic and institutional limits. For

example, there are practical limits to the height of seawalls. In cyclone prone areas, the rock

seawalls are already as much as 12-15 m high, and many seawalls in India are already 5-10 m above

the high tide line. They require large stones to reduce the constant maintenance caused by direct

wave breaking on the structure.

Hudson's formula, is an equation used by coastal engineers to calculate the minimum size of rock

armour blocks required to provide satisfactory stability characteristics for rubble structures such as

seawalls under attack from storm wave conditions. The equation was developed by the United

States Army Corps of Engineers, Waterways Experiment Station (WES), following extensive

investigations by Hudson (1953, 1959).

The Hudson formula is given by:

where W = weight of armour unit (Newton)

H = Design wave height at the toe of the structure (m)

(c) (d)


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KD = Dimensionless stability coefficient deduced from laboratory experiments for different

kinds of armour blocks and for very small damage. KD = around 3 for natural quarry rock and KD =

around 10 for artificial interlocking concrete blocks

α = Slope angle of structure

ρr = Mass density of armour (kg/m3)

g = Acceleration due to gravity (m/s2)

Δ = Dimensionless relative buoyant density of rock = (ρr / ρw) – 1 = around 1.58 for granite in

sea water

ρw =Mass density of seawater (kg/m3)

Shore Protection Manual (CERC, 1984) recommended the use of H1/10 as the design wave height in

the Hudson formula. Accordingly, the original Hudson formula was rewritten as follows using H1/10 =

1.27 Hs, in terms of the stability parameter, Ns = Hs / (Δ Dn50):

( )

⁄

whereHs is the design significant wave height at the toe of the structure (m)

Dn50 is the nominal median diameter of armour stone = (W50/ρr)1/3 (m)

At a water depth of 2 m in front of seawalls (where the tide is 1 m and storm surge of 0.2 m) the

breaker height is about 2.5m. According to the Hudson formula, the armour stone weight should be

1.75t, which is an acceptable and obtainable rock size.

However, scouring due to the presence of the seawall (Figure 8.3) could increase the water depth to

4 or 5 m. In addition, if sea level rises by 0.5 m plus storm surge of 0.5 m and tide of 2 m, the total

water depth can exceed 7 m on a steep seawall. The armour stone requirement according to the

Hudson formula would be as much as 18 t. Such rocks are unavailable, expensive or cannot be

transported. This means that increasing the height of the seawall under climate change is not an

ideal adaptation option.

Engineers have modified the designs of seawalls to incorporate reduced frontal gradient or to build a

long underwater toe. The toe is designed to stabilize the wall and force waves to break on stone

which is underwater and therefore more stable. However, the cost of these walls and their

environmental impacts are substantial. Erosion around the toe can cause the rock to sink into the

sand or subside and the toe may need to be maintained or enlarged. Such a structure might have a

base which is greater than 50 m wide, which spans the full beach zone. The natural sediment

transport is highly disrupted.


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Moreover under climate change, the maintenance of seawalls is likely to grow due to the expected

increase in SLR, storm events and storm intensity. Increased wear and tear on coastal infrastructure

will require more frequent maintenance and replacement.

Seawalls block erosion of the land. However, they have critical deficiencies:

Underwater scour: While the land erosion may be blocked, the erosion often continues underwater in front of the wall, thereby allowing larger waves to attack the structure, while impacts on downstream beaches are exacerbated.

End effects: Erosion always occurs at the end of a seawall, which means that the wall has to be lengthened, until the full sediment cell is protected.

Disruption of the natural system: The natural processes which occur during beach accretion are disturbed and the beach is lost in front of the walls.

Rock sizes: The rock sizes needed for a stable wall may be unobtainable in future.

Figure 8.2 End Effect due to seawalls.

Figure 8.3. Scour at the base of a seawall

which leads to the loss of the beach and the

need for reinforcement of the wall.


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8. 2. 4Discussion

Seawalls are placed at the top of the environmental softness ladder (i.e. the hardest option) and are

unlikely to be suitable in the future for several reasons. The beach is normally lost at the foot of the

wall, particularly at high tide, through greater wave turbulence at the base of the wall and because

of the imposition they create by burying the primary dune and berm of the beach. Seawalls block

land erosion, but erosion continues underwater in front of the walls.With a deeper profile offshore,

the walls are attacked by larger waves. While the common assumption is that the crest level can be

simply raised to fight storms and sea level rise, our calculations demonstrate that the rock sizes

required for stability of the wall become untenable or extremely costly. While the design height of a

rock seawall is large (often exceeding 5-10 m due to run-up and over-topping), splash and spray

over-topping is common in large waves. At least 2.0 m elevation will need to be added to existing

walls under climate. Another water level allowance will be needed in areas adjacent to rivers.

In addition, seawalls prohibit access to the sea, with dangerous and slippery rocks. Fishermen using

boats or nets are mostly unable to work effectively and without great risk.The walls are well known

to subside due to toe scour or collapse due to wave impacts, and need regular replacement or

topping up (Baba and Thomas, 1987).The end-effect (orbeach scour where the wall terminates)

makes it necessary to continue lengthening the wall each season. The seawalls also prevent the

natural adjustments in beach orientation needed for a stable beach and a sustainable solution to

coastal erosion.

The combination ofincreasing construction and maintenance issues, environmental impacts, loss of

amenity and loss of the beach means that the seawall ranks at the bottom of suitable methods for

preparation against climate change.

8. 3 GROYNES

Groynes are cross-shore structures, sometimes at an angle to the coast but normally perpendicular.

A typical groyne will run from above the high tide level to around 3-5 m depth offshore. They are

distinguished by a crest that is above the water level, although some may taper down offshore.

Groynes are typically constructed using heavy rocks or wave-dissipating elements made of concrete.

The groyne wall thickness is as narrow as possible to reduce the volume and cost, while remaining

stable under wave attack. Normally, they are wide enough for a truck to drive along the top and

drop rocks at the tip during construction, with sloping sides for stability. The generic category of

“groyne” may have many shapes including T-groynes, Y-groynes, or Fishtailed groynes. Groyne Fields

have more than one along the shore.

8. 3. 1 Groyne Design

Groynes have been tested over much of the world but have been mostly studied in temperate

regions there the wave climate is more variable. In India, the beaches are subjected to two distinct

and long seasons. By crossing the beach, a groyne interrupts the longshore transport. Theoretically,

the groyne acts like a natural headland. Very long groynes can fully partition the beach into smaller

sediment cells. Shorter groynes allow some sediment by-passing and are usually built to simply slow


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the longshore drift of sediment. A designer must choose four key variables: elevation of groynes,

length of groynes, spacing of groynes and the number of groynes.

First, the local wave and longshore transport conditions at the site must be analysed. The groyne

elevation in India has been normally several metres above the high tide level i.e. 3-5 m above high

tide water level. Essentially, the crest is set to block all longshore drift at the beach, However, low-

crested groynes have been adopted internationally which are described later.

In the next stage, the designer decides how much sand the thegroyne should capture and how much

should by-pass, which determines the length of the groynes. Very short groynes (e.g. 30 m) will have

a small impact as sand will go around the tip easily. Long groynes (e.g. 500 m) may cause a total

blockage, like a large port.

The spacing between groynes is a function of the beach rotations. In the seasonal wave climate of

India, the waves come from different directions in the Wet and Dry seasons. In response, the

beaches within the groyne compartments rotate so that their shore-normal is closer to the neutral

wave power direction every season (Figure 8.4). That is, the beach tries to align into the waves

within the groyne compartments.

The rotation occurs because sand is pushed to one end of the groyne compartment by longshore

currents in one season and then pushed to the other end when the seasonal wave directions change.

The amount of sand moved will depend on the strength of the longshore currents which, in turn,

depend on the intensity, orientation and height of waves. Thus, each site will display different

rotations.

The seasonal beach rotations in India need to be understood and allowed for in the design of the

groynes so that infrastructure within the groyne compartment is not attacked by waves each season.

Black and Mathew (2016) found that the beach rotation on the east coast of India near Pondicherry

was proportional to the length of the groyne compartment (Figure 8.5). They presented the

following equation to predict rotation:

( )

where L is the beach length (m). The formula above shows that short compartments will experience

larger rotations and so wider spacing is beneficial.

A groyne field is often defined by the ratio of groyne length divided by groyne spacing (L/W) (Figure

8.6). Most fields adopt values of less than 0.5, i.e. the spacing is at least twice the length of the

groyne. However, the rotation formula above shows that wider spacings lead to smaller rotations in

India and so values of L/W of around 0.1-0.2 will be more appropriate in many locations, although a

groyne field with short lengths and wide spacing may show limited benefits at the shoreline. Thus,

the designer must find the best compromise for groyne spacing, normally within the range L/W= 0.1

to 0.5. The final decision is the number of groynes. Because the beach is expected to erode beyond

the groyne field, normally the entire sediment cell will need groynes. Finally, numerical modelling

will be used to confirm the design and minimize cost without losing the benefits.


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Figure 8.4 The beach in groyne compartments rotates seasonally in synchrony with the wave

direction. The two yellow lines show the beach orientation after the NE monsoon and after the SW

monsoon.

A well-designed groyne field with correct spacing and length can substantially slow sediment erosion

within the groyne compartment, particularly if the compartments are initially filled with

nourishment. However, groynes have some well-known negative effects:

Groynes induce downstream erosion. Figure 8.7 shows examples from the Shore Protection Manual published over 30 years ago.


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Figure 8.5 Rotation of beaches in groyne compartments versus beach length

Figure8.6Agroyne compartment with the internal beach rotated into the wave direction. The beach

orientation in the groyne compartment is σ. The spacing of the groynes is W while L is the length of

the groynes.

Most published literature on groynes has come from temperate regions and so the theory of groynes in the tropics is not as well understood, which means that more computer modelling is needed to find the best dimensions for the groynes.

Groynes deflect currents offshore, sometimes in the form of a rip current. This current carries sand from the beach to deeper water offshore.

If the first groyne is too long, sand is unable to enter the compartments leaving the beach in the compartments unprotected and downstream erosion can be severe.

Normally the entire sediment cell will need groynes and so the costs for a groyne field are very large on long beaches.

Wave orientation

W

L

𝜎


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8. 3. 2 Computer Modelling of Groynes

Computer models are ideal for determining the benefits and impacts of a groyne field. The model

should use local bathymetry in the local wave climate. The model should first be calibrated to ensure

that its reproducing observed behavior. In Figure 8.8, an example calibration is shown (Black and

Mathew, 2015).

The model is simulating a groyne pair with natural beach to the north. Starting with an initial linear

beach, the model uses 3 years of wave data and shows the rotations of the beach within the groyne

compartment and the erosion downstream of the northern groyne. When compared to actual beach

adjustments seen in Google Earth images, the model was found to provide an accurate simulation of

reality (Figure 8.9). Such calibrations are essential, particularly using the actual wave climate for at

least one year to ensure that seasonal changes are considered.

A tapered groyne field (Figure 8.10) is often adopted to allow sand to enter the compartments more

easily on the upstream side while attempting to subdue the groyne effects downstream. In Figure

8.11, a tapered field of groynes which is similar to that recommended in the Shore Protection

Manual is considered. The layout has 7 groynes (Figure 8.11). The central one was 200 long and 3

groynes either side were successively 50 m shorter, i.e. 200, 150, 100 and 50 m long groynes. The

spacing was 200 m and so L/W=1, 0.75, 0.5, 0.25 respectively. An initial nourishment of 500,000 m3

was placed along the beach within the groyne compartments. Net transport is to the north under

the wave conditions simulated.


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Figure 8.7Downstream erosion at a groyne as shown in the Shore Protection Manual (1984)

The model predicts that the beaches rotate substantially each season in the compartments (Figure

8.11). Sediment is lost from the last 2 northern compartments with (L/W<0.5) and sand carried from

the south by natural longshore currents keeps the southern compartments filled. Sand is deflected

offshore at each groyne. Eventually all the nourishment sand leaks to the north, although the rate of

loss is much slower than without the groynes.

Figure 8.8Model predictions of bed levels at 0, 730 and 1000 days into the simulation. The grey zone

is sand above 1 m elevation and the green indicates groynes and rock walls. The contours show bed


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levels out to 5 m depth. The beach is rotating within the groyne compartment and the beach

downstream of the northern groyne erodes.

Figure 8.9 The Google Earth image overlaid with the shoreline position predicted by the computer

model for July 3, 2014.

This modelling example indicates that groynes can slow the natural losses of sand from a beach, but

in the case considered the losses were faster than the inputs from natural longshore drift and so the

sand was eventually lost. While the groynes block sand losses at the shore, sand can still by-pass

offshore in deeper water. This means that the selection of the groyne length is a critical design

factor. The examples show how computer modelling is needed to assess any groyne field within the

local wave environment.

Figure 8.10 A tapered groyne field from the Shore Protection Manual (1984).


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Figure 8.11 Sediment patterns at 0, 280, 430, 630, 800 and 1000 days for a tapered groyne field

(L=50,100, 150 and 200 m and W=200 m) using Indian east coast wave conditions.

8. 3. 3When and Where Should Groynes be Used?

The case studies have shown a mixture of successes and failures with groynes. However, in assessing

each groyne project, difficulties arise for several reasons.

First, every groyne field appears to be different, with different lengths and different spacings. For

example at Panathura, a much longer groyne with nourishment of the beaches to the south may

have been more successful. For many reasons that were not totally scientific, only a 33 m long

groyne was built. This is relatively small for a coast which stretches 3 km to the south.

Second, pressures that come to bear during a project in India, can lead to design changes between

design and construction. For example, the original design at Panathura recommended groynes that

were 125 m long, but a 33 m groyne was built instead as a trial.

Third, each segment of coast along the Indian coast is fundamentally different. Some coasts like

Kerala or Ponicherry have net transport which is dominantly in one direction. Others like Goa and


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Maharashtra or within small embayments have net transport which is close to zero (just alternating

each season).

Fourthly, groynes have been placed in locations with very small sediment inputs. The concept of

capturing natural sand will fail in these cases.

Fifth, groyne fields may be designed to deliberately leak sand. Usually there will be pressure to

ensure that downstream beaches receive inputs and so a “half-way” design is put in place and the

groyne is then seen by some as being unsuccessful. The groynes at Bournemouth were designed to

leak because the downstream residents wanted sand on their beaches, but the cost of groyne

maintenance and sand replenishment is very large. This may be unsustainable in India. In essence,

the politics of beaches and the delivery of sand downstream will often lead to decisions like the

construction of groynes which are shorter than the designer wants.

Sixth, while a method of coastal protection may be considered a failure in some locations, the failure

may be due to the design engineer rather than a failure of the whole coastal protection method. The

engineer may not have considered the environmental conditions (especially net longshore transport)

and factors beyond their control may have influenced the final decision. Insufficient data collection,

proper analysis or inadequate computer modelling may be also at fault. Thus, while one groyne field

may be successful in a location, the same design may not be suitable elsewhere.

Seventh, there are three key variables to consider, i.e. number of groynes, spacing and length. In

India, these factors vary sufficiently and appear “random”, with different lengths and spacings being

noted, even within a single groyne field. There are numerous forms of groyne like T-groyne, fish-tail

groyne, curved groyne etc.

Overall, the question of what should be built, which takes account of the existing environment and

under climate change, needs to be answered. The key message in this description is that all beach

works should have a primary goal of putting the beach onto an alignment that leads to neutral net

longshore sediment transport. This can lead to downstream impacts (whether using reefs, groynes

or any other method) because deliveries to neighbouring zones will reduce. Thus, the full sediment

cell must be considered. However, once a beach is neutral, it’s much easier to sustain and beach

nourishment within the cell has extremely positive benefits, lasts for a long time and allows the

beaches to be prepared for climate change.

At smaller scales, groynes can be used to rotate beaches within smaller compartments. However,

because they cut off the longshore drift, the full cell needs to be treated. The groynes are then

placed only to reduce longshore transport like Bournemouth, rather than act to find a new beach

alignment. In these cases, the use of an offshore reef would be preferred because reefs allow by-

passing of sand at the shoreline.

In general, groynes have no positive benefit on neutral beaches. If neutral beaches are eroding, the

cause will be sand lost due to reclamation, mining or human interference at the shoreline disrupting

the berm and beach. Sometimes neutral beaches can be temporarily out of alignment due to annual

or decadal oscillations in the wave climate and disruption of the cross-shore transport during periods

with more storms. However, the sediment will still be within the sediment cell.


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8.4 OFFSHORE REEFS, BREAKWATERS AND ISLANDS

Offshore reef is a relatively new means of coastal protection in India. However, natural reefs and

islands have been protecting the Indian coasts since the dawn of time. The first artificial reef to be

built in India was at Kovalam. Large sand-filled geocontainers were adopted. Another reef of

geocontainers is currently under construction at Mirya, Ratnagiri. Reefs are a construction-based

solution, which fit into the “soft” solution category because they are offshore and underwater (crest

at high tide or lower). The artificial reefs are primarily built to protect the coast, but they also have

several public amenity benefits: improved fishing; snorkeling for visitors; and improved safer

beaches. They are adopted in several countries internationally.

8. 4. 1 Design of Offshore Reefs

An offshore reef acts on the waves, which are the most common cause of erosion. Other land-based

structures like groynes and rock walls act on the effects at the beach. Philosophically, it is preferable

to fix the cause rather than putting a “bandage” on the effects. Any structure offshore will help to

protect a coastline, but the degree of protection depends on the design. Parameters such as crest

height, longshore length, and distance offshore all need to be appropriately set. Optimum

parameters will give the appropriate beach protection, while still allowing sediment to pass naturally

along the shore, thereby eliminating downstream impacts.

Black and Andrews (2001a) digitized the shapes of numerous salients in the lee of natural

submerged and emerged reefs. They defined the variables in Figure 8.12. Their analysis showed that

the size of the salient was primarily dependent on two variables: the longshore length of the

structure and the distance offshore (Figure 8.13a,b). They obtained the following relationship to pre-

determine the size Yoff of the salient at its widest mid-point:

Xoff/B = 0.5 (B/S) -1.27 (1)

Further research (Black and Andrews (2001b) indicated that the shape of the salient was described

by an asymmetric sigmoid (Figure 8.14).

Knowing the geometry and shape allows the salient to be forecast prior to construction of an

offshore structure and without computer modeling. However, numerous calibrated simulations of

the computer models later showed that the theory could be reproduced by the models.


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Figure 8.12 Definition of variables defining a structure and salient.

Figure 8.13 Salient Xoff/B versus B/S for reefs and islands (from Black and Andrews, 2001a)

8538 c1

Rank 1 Eqn 8090 [AsymSig] y=a+b/(1+exp(-(x-dln(2 1/d -1)-c)/d)) d

Adj r 2 =0.99787173

a=-9.3873315 b=135.21325 c=339.83375

d=20.302925

0 100 200 300 400 500 Longshore Distance (m)

0

25

50

75

100

125

150

Offshore Distance (m)

Figure 8.14 The asymmetric sigmoid shape of salients (from Black and Andrews, 2001b).

S

B

Xoff

DRDL

Dtot

Yoff

Offshore Obstacle

Salient Undisturbed Shoreline

W


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The physics is explained simply in Figure 8.15a, b. Reefs, which block waves, are called dissipaters.

The reef produces a wave shadow zone at the shore. When waves arrive from different directions

the shadow zone moves as the wave angle changes (Figure 8.15a). This produces a shoreline wave

shadow much broader than the reef, and leads to protection along a longer section of coast than the

longshore reef length. The maximum protection occurs in the line of the dominant wave direction

and grows less to either side, which forms the common salient shape sketched in Figure 8.15a. The

length of shoreline protected can be up to 8 times the longshore length of the reef (Black and

Andrews, 2001a), which substantially reduces the cost per metre of coastal protection.

Alternatively, submerged reefs can also help protect a coast by rotating the waves. Waves arriving at

an angle to the coast drive littoral sediment transport in the direction of the waves (Figure 8.15b).

Thus, if the wave is rotated (e.g. onto a more shore-parallel angle), the littoral drift can be changed

to the benefit of the beach. Prof Black patented this powerful concept of wave rotation on reefs for

coastal protection. The third option is a wave reflector. In this case, the offshore structure is

constructed to reflect the incoming energy, rather than induce wave breaking. Once again, this

reduces the wave height at the shore and leads to accumulation of sediment in the form of a salient.

Figure 8.15.(a) Dissipating reef and (b) rotating reef

8. 4. 2Salients

Black and Andrews (2001) examined salients in the temperate waters of Australia and New Zealand.

No reefs or islands in the tropics were considered.

To test if the theory was applicable to the tropics, two further investigations have been undertaken:

(i) Salients formed inside the lagoons of tropical reefs at Mauritius in the southern Indian Ocean and

(ii) Salients formed in the lee of reefs and islands on the coast of India. For each salient case, the

following key measurements were made using Google Earth images:

• Reef length (B) in the longshore direction (m)

• Baseline location where the salient projects beyond the natural beach (length=Dtot)

• Cross-shore distance (S) from the baseline to the reef

• Apex cross-shore width of the salient (Yoff)

(a) (b)


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Using the two parameters B and S, the theoretical salient width was calculated and compared to the

actual measured size.

There are several well-formed salients along the shoreline around the Indian coast (Figure 8.16). The

best-fit curve is linear with a gradient of 0.99 (R2=1.00). The gradient indicates that actual salient

widths are 1% larger than predicted by the formula, which is small and within the data scatter. Thus,

Black and Andrew’s formula derived in temperate regions is valid for Indian conditions.

Figure 8.16 Salient at (a) Enayam, (b) Hadin, (c) Majali, (d) Palissery,

8. 4. 3Discussion

Reefs/islands are a very natural solution for coastal erosion. They simply copy the example set by

nature. Most importantly, once the beach salient is formed, they allow natural bypassing of sand.

Many stakeholders prefer this solution because it meets most of their aspirations. The reef has

minor visual impacts, requires no construction on the beach, can be modified as a water sport

enhancement (e.g. surfing). The habitat they provide can also greatly benefit marine life and fishers.


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The benefit/cost ratios for well-designed reefs can be very large, particularly in tourism areas. In

addition, reefs deal with the waves, which are the cause of the erosion, rather than trying to deal

with the effects at the shore. This makes it ideal for Climate Change adaptation. The crest can be

raised, if required.

8. 5 OVERALL CONCLUSIONS

Much of the coastal protection in India is focused on protecting the “front row” of houses or

infrastructure. A broader spectrum of issues needs to be engaged in the decision making so that the

shared resources of the coastal zone are all enhanced.There is a need to visualize a future without

beaches if the present unscientific developmental practices continue. At the same time, sand

supplies are dwindling from the rivers. Very little sand comes naturally from offshore and this will

not change when sea levels rise. Thus, sand-based solutions rank best on the Environmental Softness

Ladder proposed in the present Adaptation Guidelines (i.e. the softest) and are the preferred option

for climate change adaptation.

Projects in India are based on the construction cost, land or income loss only. However, every

project will have maintenance costs, offset benefits and sometimes downstream impacts that lead

to more expenditure. The environmental costs may be substantial. Losses of beach amenity, fishing

access, degradation of the coastal ecosystem and public distaste for poor coastal protection

measures all play a role in project value.

The analysis has shown that existing seawalls should be modified to have gaps some 300 m long

every 2 km of coast. The rocks from the existing seawalls could be used to help construct short

groynes on either side of the gaps. The gap should have a shorter groyne on the upstream side (e.g.

50 m) and longer on the downstream end (e.g. 100 m). Alternatively, an offshore reef could be

constructed on the downstream end of the gap. The reef would have the crest at high tide level and

would be about 100 m long (in the longshore direction) and some 100 m offshore of the seawall.

Groynes rank better than seawalls on the Environmental Softness Ladder proposed in the present

Adaptation Guidelines. They are designed to segment the sediment cell. In India, the variation in

length and spacing of existing groynes has not been shown to relate to the local longshore sediment

transport conditions or to the size and energy of the beach within the sediment cell. Indeed,

different lengths and spacing have been used in the same sediment cell, without any plausible

scientific explanation.

Groynes create a downstream effect. Their job is to capture sand, and so the beach beyond the

structures is likely to suffer. The designer must understand and clearly know the volumes of sand

coming as longshore transport and what effects the capture of sand around a structure will have on

downstream beaches. We’ve seen numerous cases in our Indian case studies where groynes located

in the midst of a long sandy beach have had serious consequences in adjacent regions. This led to

construction of additional groynes to fix the problems they caused themselves. The same has been

seen with seawalls and their “end effects” which led to more seawalls.


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However, groynes may have a place in coastal protection. They are likely to succeed in several

circumstances:

a) When they are very long and deliberately break a single sediment cell into multiple compartments or smaller cells. These smaller cells may need initial nourishment and the groyne simply acts to hold that sand on a section of beach, with no expectation of inputs/outputs. That is, they mimic a large headland which may bound a sediment cell;

b) When the entire beach is protected with groynes and the compartments are initially filled with nourishment. The groynes then act to slow the longshore drift and hold the sediment within the compartments, thereby reducing renourishment requirements;

c) When the groynes are short and simply act to protect the upper beach. This assumes that longshore drift is mostly uni-directional;

d) When the groynes have a low crest (around 1-2 m above high tide level), so that sand can build up to create the beach but any excess sand passes freely from one compartment to the next.

Softer on the Ladder are offshore breakwaters and offshore reefs. The former will be a large

structure with the crest out of the water, like an island. The latter has the crest at or below high tide.

Our analysis of Indian beaches has shown that islands and reefs conform to the theory presented

which showed that offshore structures cause the beach to build out to seawards in the form of a

salient or tombolo. The beach is thereby widened without the need for structures at the shoreline.

This can overcome problems with urbanization which has developed too close to the sand dune and

beach. While the beach grows outwards, further migration of houses and infrastructure to seaward

will need to be blocked. There are examples of large salients in Karnataka but houses have been built

on the primary dune and locals are claiming that the beach is eroding, even though the beach is

actually several hundred metres seaward of the natural beach line.

Numerous other benefits of offshore solutions were identified including marine habitat for fish and

other marine species, the ability to add amenity like surfing and the minor visual impact they cause.

A salient builds to a dynamic equilibrium size and then allows sand to pass freely along the beach.

Thus, the downstream impacts are small, particularly if the salient formation is created using

nourishment to overcome initial sand-trapping effects. The cost per metre of reefs is higher than a

rock seawall, but a typical reef protects the beach up to 8 times its longshore length (Black and

Andrews, 2001) which reduces its cost disadvantage.

Reefs and islands thereby have a much lower environmental impact and are ranked in the centre of

the Environmental Softness Ladder. Under climate change, they provide a benefit/cost ratio that is

substantial. One of the main features of reefs and islands is that they act on the waves, which is the

cause of erosion, rather than trying to put a “bandage” on the effects.

Notably, if the whole coast is suffering sediment deficits due to reduced river inputs, mining or other

causes, the beach in the lee of a reef or island will still retreat, even though it will stay forward of

adjacent shoreline. Erosion will occur with groynes and seawalls also. If sand mining is not blocked,

sand will need to be added to the beach as nourishment or the beach will need to be realigned.

Ultimately, our studies have reinforced the notion that “the beach is the best form of coast

protection”. To prepare for Climate Change, the sand resources need to be protected. In addition,


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any structures which capture sand, deplete the downstream zones or change the shoreline dynamics

need to be abandoned.

REFERENCES

Black, K. and Andrews, C. (2001a). Sandy Shoreline Response to Offshore Obstacles, Part 1: Salient

and Tombolo Geometry and shape. In: K. Black (ed) Natural and Artificial Reefs for Surfing

and Coastal Protection. Special Issue 29, Journal of Coastal Research, 82-93.

Black, K. and Andrews, C. (2001b). Sandy Shoreline Response to Offshore Obstacles, Part 2:

Discussion of Formative Mechanisms. In: K. Black (ed) Natural and Artificial Reefs for

Surfing and Coastal Protection. Special Issue 29, Journal of Coastal Research, pp. 94-101.

Baba, M. & Thomas, KV. (1987). Performance of a seawall with frontal beach, Proc. `Coastal

Sediments 87', American Society of Civil Engineers, New Orleans, 1051-1061.

Black, K and Mathew, J. (2016). Puducherry Beach Restoration Project: Task 2: Detailed design of

finalized alternative. Report submitted to National Institute of Ocean Technology (NIOT),

Chennai, May 2016, 182 p.

Black, K.P., & Mathew, J. (2015). Puducherry Beach Restoration, Task 1: Feasibility Studies for Design

Alternatives. Submitted to National Institute of Ocean Technology (NIOT) by Sanctuary

Beach Pte Ltd. 270 pp.

CERC (1984).Shore Protection Manual, 4thEdn.Coastal Engineering Research Centre, US Army Corps

of Engineers, Vicksburg, MS.

Hudson, R. Y. (Ed.). 1974. “Concrete Armor Units for Protection Against Wave Attack,” Miscellaneous

Paper H-74-2, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS.

Hudson, R. Y. 1953. Wave forces on breakwaters. Trans. Am. Soc. Civil Engrs, Vol. 118,pp 653-674

Hudson, R. Y. 1959. “Laboratory Investigation of Rubble-Mound Breakwaters,” Journal of the

Waterways and Harbors Division, American Society of Civil Engineers, Vol 85, No. WW3, pp

93-121.

Kudale, M.D. andSitaramaSarma, A.V. (2010). Technical Memorandum on Guidelines for Design &

Construction of Seawalls, Central Water and Power Research Station, Pune, India, 23p


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9 „COASTTOOL‟ FOR PLANNING COASTAL PROTECTION

9.1 INTRODUCTION

Different coastal protection solutions will be needed for different beach environments, e.g. long sandy beaches, pocket beaches, cliffs, muddy coasts, rocky beaches all have different character. However, the input design parameters like wave height and water level are also highly variable along the Indian coast. The Indian research institutes acknowledge that climate change will not be the same everywhere along the Indian shoreline and that localized refinement is important, rather than adopting a single water level or wave climate for all of India. Moreover, it‘s well understood that tides, wave climates and storm surge vary substantially from north to south and from east to west along the Indian coast. Even simple factors like the beach angle will greatly change the impacts of climate change. And sheltered beaches with small waves will be less impacted than beaches fronting major wave corridors.

Thus, a software design tool is needed to provide engineers and local enthusiasts withinformation for decision making before designing a structure.CoastTool is developed as a software design tool which:

Transforms the offshore data provided by the Institutes‘ data to the nearshore

Assimilates existing data on tides, winds and waves

Provides information about longshore sediment transport, beach grain sizes and beach morphology

The software Tool will be easy to use but will have considerable complex science embedded, thereby eliminating the need for the non-expert or busy engineer to deal with the mathematics.

9.2 THE BASIC DESIGN OF COASTTOOL

For easy access, a front-end will be written in Visual Basic or HTML if the Tool is to reside on a website. This will ask the relevant questions of the user including:

Name of beach

Latitude and Longitude of project

A clickable map to allow users to find their location

The output from CoastTool will be:

Sea level predictions for 2050 and 2100

Tidal amplitudes and phases

Location and size of sediment cell with presence of headlands and their length

Wave data: wave height, angle and period statistics including extreme 1:30 year conditions with set-up and run-up levels

Design water levels

Longshore transport fluxes: north/south, net, gross

Beach data: orientation, length, width, grain size, elevation, slope, classification, morphology

Presence of rivers and names: estimated flows in the dry and monsoon

Presence of structures: ports, groynes, seawalls, natural reefs or islands,

Presence of extraction industries


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The tool will hold relevant Google images to show the key features for each site and confirmation of the correct selection by the user. It will operate by storing and cataloguing input data (i.e. waves, tides, sea levels etc.) in computer files tagged by latitude/longitude, place names and statistics available. Some information will be unavailable and the software will identify those cases and allow the user to input relevant information, if required.

The required wave information will be taken from hindcast wave conditions which are now available for 36 years along the Indian coast. In the first version, CoastTool will embed just two wave time series, i.e. one for Karnataka and one for Maharashtra. The altered wave climate under climate change from the Institutes will be embedded also.

This appendix provides the mathematical background for the formulae to be adopted. However, all of this will be embedded in the software and so the user won‘t have to deal with the complex mathematics.

9.3 BACKGROUND

The sea is fluid and the forces that move the fluid up, down and sideways are numerous. We can think of the sea like a bathtub, rocking and rolling with myriad forces, including forces from space like the pull of the sun and the moon which drives the tides.

The science can identify what to expect in the future, e.g. what water levels to prepare for, whether cyclones will migrate more south as seas become warmer, or monsoon seasons get longer, wetter, shorter etc. All of these factors and many more determine outcomes at the coast.

In addition, waves play a dominant role. Any alteration to the direction or size of the waves due to climate change can be expected to dramatically alter beach alignments, change the direction or intensity of net sediment transport and ultimately lead to erosion or accretion adjustments that need to be forecast.

To answer some of these scientific questions, the TA team has requested four of India‘s best research institutes to explain the future of water levels, cyclones and waves. These inputs can be incorporated into the guidelines in several ways. First, a design water level can be specified. Secondly, forecast changes in the weather can be utilised for improved design of beach protection methods.

9.3.1 Water Level Rise

Many factors affect sea levels. Offshore, the key factors are:

Tides

Large-scale ocean circulation

Oceanic gyres

Coastal currents

Coriolis deflection of currents

Local wind set up

Cyclones

Barometric pressure

Sea level rise due to climate change

Inshore, the key factors include:

Wave height

Wave period

Wave direction

Surfzone width


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Beach gradient

Sand grain size

Sand bars

Surfzone set-up

Surf beat

Swash and run-up

Surf zone currents

Rainfall

These parameters determine the level of the sea at the coast, and the ultimate re-sculpting or retreat of the coast in response to waves and storms.

9.3.2 Tides

The tides around India vary from small ranges in the south (order 0.8 m) to large ranges in the north (order 4-5 m). The largest tides occur around Gujarat where ranges of 7 m occur (Figure 9.1).

Figure 9.1Water levels at few locations along the Indian coast (Source :Sanil Kumar et al

2006)

9.3.3 Large-Scale Ocean Circulation

An example of global circulation is shown in Figure 9.2. Currents travelling towards or along the coast will elevate sea levels. The currents in the northern portion of the Indian Ocean change their direction from season to season in response to the seasonal rhythm of the monsoons. The effect of winds is comparatively more pronounced in the Indian Ocean. Monsoon winds in Northern Indian Ocean are peculiar to the region, which directly influence the ocean surface water movement [North Indian Ocean Currents].


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The north-east monsoons drive the water along the coast of Bay of Bengal to circulate in an anti-clockwise direction.Similarly, the water along the coast of Arabian Sea also circulate in an anti-clockwise circulation.

In northern hemisphere summer, due to the effects of the strong south-west monsoon and the absence of the north-east trades, a strong current flows from west to east. Thus, the circulation of water in the northern part of the ocean is clockwise during this season.

Figure 9.2Example of global ocean circulation.

9.3.4 Oceanic Gyres

An ocean gyre is a large system of circular ocean currents formed by global wind patterns and forces created by Earth‘s rotation (Figure 9.3). The Indian Ocean Gyre is a complex system of many currents extending from the eastern coast of Africa to the western coast of Australia. The northern part of the system circulates between the Horn of Africa and the Indonesian archipelago. It is sometimes called the Indian monsoon current.It is one of the very few currents in an ocean gyre that change direction

Figure 9.3Example of oceanic gyres in the global oceans. The Indian Ocean gyre in the southern hemisphere is a dominant feature.


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9.3.5 Coastal and Oceanic Currents

Coastal currents are intricately tied to winds, waves, and land formations. Winds that blow along the shoreline—longshore winds—affect waves and, therefore, currents

Oceanic currents are driven by several factors. Tides create a current in the oceans, near the shore, and in bays and estuaries along the coast. These are called "tidal currents." A second factor that drives ocean currents is wind. Winds drive currents that are at or near the ocean's surface. Winds drive currents near coastal areas on a localized scale, and in the open ocean on a global scale. A third factor that drives currents is thermohaline circulation - a process driven by density differences in water due to temperature (thermo) and salinity (haline) in different parts of the ocean. Currents driven by thermohaline circulation occur at both deep and shallow ocean levels and move much slower than tidal or surface currents.

An important feature of the surface currents of the Indian Ocean (Figure 9.4)is the appearance of Equatorial Jet during the transition periods before northern hemisphere summer (April-May) and winter (November-December). The currents in the North Indian Ocean show greater response to the reversing monsoon winds (Shenoi et al., 1999).Table 9.1 presentscurrents at shallow water locations along the Indian coast

Figure 9.4Schematic of major surface currents in the Indian Ocean during winter and summer: (a) the northeast monsoon and (b) the southwest monsoon. The major currents depicted are: South Equatorial Current (SEC), Northeast Monsoon Current (NMC), Equatorial Counter Current (ECC), Equatorial Jet (EJ), East African Coastal Current (EACC), Somali Current (SC), Southwest Monsoon Current (SMC), West India Coastal Current (WICC), East India Coastal Current (EICC) and East Madagascar Current (EMC). The EJ, though depicted in the schematic for winter, does not appear either during summer or winter monsoon season; it appears during the transition period in April–May and November–December. The thickness of the curve represents the relative magnitude of the current (source: Shenoi et al, 1999)

9.3.6 Coriolis Deflection of Currents and Coastal-Trapped waves

Because the Earth rotates on its axis, circulating water is deflected toward the right in the Northern Hemisphere and toward the left in the Southern Hemisphere(Figure 9.5). This deflection is called the Coriolis effect. Thus, a current travelling south down India‘s west coast will deflect offshore. This has the effect of lowering water levels at the coast. The magnitude depends on current strength and Latitude. A current travelling to the north on the west coast will raise water levels. An oscillating current can also occur, known as coastal-trapped waves (Middleton and Black, 1994)

In CoastTool, the set-up at the shore is estimated most simply as,


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where ∆Z is the sealevel change at the coast, f is the Coriolis parameter, V is the longshore

velocity averaged over the continental shelf (positive to the north) and ∆X is the local width

of the shelf.

Table 9.1 Currents at shallow water along the Indian coast (Source: Sanil Kumar et

al.,2006)

The Coriolis parameter is,

( ) where N is the latitude in radians (positive in the northern hemisphere). Currents averaged through the water column are typically less than 0.5% of the longshore wind speed when averaged across the shelf. A value of 0.5% is used in CoastTool so that the set-up is not


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under-estimated. Notably, the currents are highly dependent on bathymetric topography, seabed friction, depth of water and wind stress and so CoastTool only provides an estimate. A more sound approach would use computer models to simulate the full hydrodynamic equations over real bathymetry. Studies of storm surge for Port Phillip Bay in southern Australia showed that the deflection of longshore currents by Coriolis force caused larger water level rises at the coast than the direct action of onshore winds pushing water against the coast (Black, 1992). The effect of Coriolis deflection grows bigger at higher Latitudes, from south to north India.

Figure 9.5Deflection of currents due to the Coriolis force which is induced by the rotation of

the Earth.

9.3.7 Cross-shoreWind Set Up

'Wind setup' is thevertical rise in the still water level on the landward side of a body of water caused by wind stresses on the surface of the water (Figure 9.6). The wind blows onshore and causes sealevel to push up against the coast. The setup, nw depends on the square of the wind speed, wind fetch and water depth,

where,

ρa is Density of air.

CDWis Drag coefficient due to wind stress given by

U : The surface wind speed at an elevation of 10 m above sea surface,


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(

)

Uz : Measured wind speed at an elevation z m

F : The fetch along the wind direction (m)

ρ : Density of sea water .

g : acceleration due to gravity 9.81

: Average water depth along the fetch.

Mostly the wind setup occurs on the continental shelf, which defines the wind fetch.

Figure 9.6 Coastal water level setup due to wind.(Read more:

http://teachmefinance.com/Scientific_Terms/Wind%20setup.html#ixzz3tvkAmN3V)

9.3.8 Wave Set Up

Wave setup is the change in the water level inside the breaker zone in the presence of waves (Figure 9.7),


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(

)( )

where, h is water depth hb is the breaker water depth. A wave of given height will break at this water depth.

ηd is wave set-down. The change in the water level outside the breaker zone in the presence of waves.

( )

whereHb is the wave breaker height. A wave of this height will break at the given water depth.

γ is the wave breaking index. The ratio of wave height to water depth at which the wave will break.

k is the angular wave number. The number of wave units which are contained within unit horizontal distance.

L is the shallow water wave length

. (

)or √

L0 is the deep water wave length.

Fa is a function used in shallow water wavelength approximation.

Ga : Function used in shallow water wavelength approximation.

(

)

g : acceleration due to gravity where g=9.81

The wave group speed in shallow water is

( )

and shallow-water wavelength can be calculated as,


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Figure9.7Beach parameters showing wave setup and wave run-up.

9.3.9 Wave Run-Up

Wave run-up is the maximum vertical extent of wave uprush on a beach or structure above

the still water level (SWL) (Sorensen, 1997).

√

9.3.9.1 Transforming wave height and angle from offshore

For CoastTool, wave statistics are available offshore only. Thus, the waves have to be

transformed to the break point. The wave characteristics vary spatially (Table 9.2). Wave

height transformation is given by,

Hb = KRKSKf H0

where Ho = offshore wave height; Hb = inshore wave height at the breakpoint; KR =

refraction coefficient; KS = shoaling coefficient; Kf = frictional coefficient.

The refraction coefficient is given by

KR (cos / cos ) / 0 2

1 2

where 0 = offshore wave angle; 2 = inshore wave angle.

The shoaling coefficient is given by

K C Cs g g ( / ) /

0 2

1 2

whereCg0 = group speed offshore; Cg2 = group speed inshore

The group speed is obtained using a Newton Raphson iterative solution of the linear wave

dispersion relation:

)tanh(2 kdgk

Where = radian frequency; g = gravitational acceleration (9.81 m.s-2); k = wave number;

d = water depth.


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The equation for depth-limited breaking is given by

H db b

where = breaker index often taken as 0.78. Thus, the depth at breaking can be found knowing the inshore wave height.

The friction term is based on the non-dimensional orbital velocity, and is,

( ⁄ ) ( )

where Cf is the friction coefficient (taken as 0.2), the radian frequency is = 2π/T, T is the wave period, UB is the bed orbital velocity, g is gravitational acceleration, ∆x the size of the iterative steps from offshore to inshore and is the wave angle. Friction losses increase with bed orbital motion and as the wave period drops. However for CoastTool, the friction multiplier Kf is treated as a constant = 0.97, i.e. the waves lose 3% of their height as they cross the inner shelf to the beach due to friction. This is a highly conservative value so that longshore transport rates are not under-estimated.

The wave angle transformation is calculated by Snell‘s Law

2

2

0

0 sinsin

CC

where Co = phase speed offshore; C2 = phase speed inshore at the breakpoint.

The dispersion relation for linear waves is,

( )

where ω is the radian frequency (2π/T), k is the wave number (2π/L). An iterative Newton-Raphson method is adopted to solve the equation, knowing the period T and the water depth h. The wave phase speed is given by,

9.3.10 Cyclones

Cyclones have a major impact on the coast. Our study is investigating cyclones with the assistance of the Indian Research Institutes.

9.3.11 Barometric Pressure

The inverse barometer (IB) is the correction for variations in sea surface height due to atmospheric pressure variations. A 1 mbar atmospheric pressure change corresponds to a linear response of the sea level of about 1 cm, although there can be local variations due to land effects. The inverse barometer correction B (cm) can be computed from the air pressure P (mbars):

B = 1013 - P

Notably, the inverse barometer effect is modulated by large scale bathymetry and coastal morphology which can only be accurately treated by computer models. The value 1013 mbar is the long-term average of local air pressure at the site and may vary along the Indian coast(Figure 9.8).


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Figure 9.8Barometric pressure varies with elevation and location. Low atmospheric pressure causes the sea level to rise and augment the storm surge felt at the shoreline.

Table 9.2Wave characteristics at different locations based on measured data (Source: Sanil Kumar et al.,2006)


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9.3.12 Longshore sediment transport

Bedload is the transport of sand grains along the seabed and suspended load is the

transport of sand in the water column. Waves act to lift sediment from the seabed into the

water column. In the presence of currents, this sand is moved alongshore and cross-shore.

The largest transport usually occurs in the longshore direction when waves arrive at an

angle to the coast. Several researchers have studied longshore drift, and the equations in

CoastTool are described below.

9.3.12.1 Kamphuisformula

The Kamphuis (1991) formula for longshore sand transport along a beach (Q m3h-1) is given

by,

Q=7.4 Hs2 Tp

1.5 mb0.75 d50

-0.25sin0.6(2αb)

where Hs is significant wave height at the breakpoint (m);

Tp is peak wave period (s);

mb is the local beach slope at the breakpoint;

d50 is the median grain size (mm);

b = subscript denoting wave breaking condition;

αb = angle of breaking waves relative to the local shoreline.

The coefficient ―7.4‖ incorporates typical sand density and porosity.

9.3.12.2 CERCformula

The well-known CERC equations (SPM, 1984) for longshore transport Q (m3h-1) are:

( )

and

( )

where K is a dimensionless empirical coefficient,ρs and ρ are sediment and water densities (kgm-3) respectively, a’ is the volume of solids/total volume (accounts for the porosity), g is gravitational acceleration, Hrms,b is the RMS wave height at the breakpoint,Cgb is the group speed at the breakpoint, and αb is the breakpoint angle relative to the shore.The value of K incorporates the grain size effects (and other surfzone factors like bars, ripples etc.) and has been found to vary over a broad range from 0.2 to 1.6 (Bodge and Kraus, 1991). This can cause a factor of 8 variation in the predicted longshore transport rates. The value chosen for CoastTool is 0.39 (Bodge and Kraus, 1991). Notably, some authors adopt values for K in the range 0.70-0.77 (e.g. van Rijn, several references).

In relation to the K value, Wang et al. (2002) state:

―Based on the original field study by Komar and Inman (1970), the Shore Protection Manual recommends a K value of 0.39. Bodge and Kraus (1991) re-examined the derivation and suggested a lower K value of 0.32. Schoonees and Theron (1993, 1994) re-examined the 46 most reliable of the 240 existing field measurements that have been compiled and


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recommended a K value of approximately 0.2. In a number of GENESIS model applications, where calibration involves adjustment of the K value to maximize replication of observed shoreline changes and net and gross Longshore Sediment Transport rates based on local knowledge of the sediment budget, optimal K values often range from 25 to 50 percent of the value recommended in the Shore Protection Manual.‖

Our selection of K=0.39 is larger than most of the values described above and so predictions with CERC are likely to be conservative on the high side. Moreover, the results in the large wave flume of Wang et al. (2002) support this conclusion. These authors suggest that the best way to choose the value is to calibrate the model against shoreline changes, which we was done for the east coast of India (Black and Mathew, 2015) and they found that K=0.39 was appropriate.

The CERC equation is derived from the wave power equations. In a mixed sea state, the wave power is associated with the RMS wave height (Hrms

2) rather than the significant height (van Rijn, several references). Several authors have incorrectly applied the significant height in the CERC equation, which leads to transport rates 2.4 times larger (=0.72.5) than those predicted by the Kamphuis equation. Indeed, some researchers (including Vijayakumar et al. (2014)) have used Hs rather than Hrms which helps to explain the major discrepancies they obtained. Moreover, Wang et al. 2002) have used Hs instead of Hrms and they found that CERC grossly over-estimated by a factor of 3 or more. Van Rijn correctly reported that the Kamphuis equation is associated with the significant height at the breakpoint while CERC uses the RMS height.

In a sea with Rayleigh distribution of wave heights (Lee and Black, 1978; Black, 1978), the relationship between the two height statistics is,

Hrms = 0.707Hs

This correction is applied to the significant heights coming from wave time series for the CERC equations, but not in the Kamphuis equation.

9.3.12.3 ModifiedKamphuis formula

Kamphuis introduced a period dependence into the longshore transport equations to parameterise the intensity of breaking. Intense breaking was expected to increase concentration at the breakpoint and thereby cause an increase in total load. However, while breaking intensity does have an impact on local suspension, the period effect does not occur across the full surf zone and beyond the breakpoint. The second influence of period relates to the asymmetric orbital motion under long period waves which drives sand shorewards and longshore.

Mil-Homens et al. (2013) presented evidence to show that the grain size and wave period dependence in the Kamphuis equation was not in agreement with a wider and more modern dataset. Much more information from beaches was available to Mil-Homens et al. in 2013 than to Kamphuis in 1991. While they retained the same essential formula, they varied the power dependence of the input parameters and presented the following modified Kamphuis equation:

Qt,mass= 0.15 (s/(s-)) (Tp) 0.89 (mB)0.86 (d50)-0.69 (Hs,br) 2.75 [sin(2br)]0.5

whereQt,mass is the dry mass in kgs-1. All other terms have been defined before. Notably van Rijn found that the modified Kamphuis formula given by Mil-Homens et al. (2013) contained two errors (His Personal Communication). Van Rijn asserts that the above equation is the correct one.


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In this formula, the wave period has a much lower power of 0.89, compared to 1.5, and so its effect is substantially reduced. The breaking wave height dependence is now to the power 2.75, rather than 2.0 and so its effect is strengthened. Notably, the new power of 2.75 is closer to the CERC formula with 2.5. The seabed gradient and angle influence has also been slightly changed. The grain size influence has been substantially changed with the power going from -0.25 to -0.69.

9.4 DEFINING THE PARAMETERS NOW, IN 2050 AND 2100

The Table 9.3 shows the parameters and the likely changes in values under climate change. Our study is working with the Indian institutes to provide best estimates of the missing values. Monsoon onset dates are likely to become earlier or not to change much while monsoon withdrawal dates are likely to delay, resulting in a lengthening of the monsoon season in many regions. The increase in seasonal mean precipitation is pronounced in the east and South Asian summer monsoons. Future increase in precipitation extremes related to the monsoon is very likely in South Asia. Indian monsoon rainfall is projected to increase.

Table9.3The parameters and the likely changes in values under climate change

Parameter 2015 2050 2100

Wind strengths

West wind vector

North wind vector

Monsoon duration

Wave height, period

Tides

Cyclone frequency

Cyclone intensity

9.5 SEA LEVELS AT THE SHORELINE

The latest IPCC report (2013) finds that "It‘s very likely that the mean rate of global averaged sea level rise was 1.7 [1.5 to 1.9] mm/yr between 1901 and 2010, 2.0 [1.7 to 2.3] mm/yr between 1971 and 2010 and 3.2 [2.8 to 3.6] mm/yr between 1993 and 2010. Tide-gauge and satellite altimeter data are consistent regarding the higher rate of the latter period"

In relation to other factors, Figure 9.9 shows the combined influence on the coast of winds,

waves and the combination. This indicates maximum rises of 1.5 m, without the addition of

set-up in the surf zone and run-up on the beach. With a SLR or 0.7 m, plus the other factors,

the level may be up to 3 m above high tide at times.

9.6 COASTTOOL EXAMPLE

The Figure 9.10 shows the input data and the final water level being calculated in this


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Figure 9.9 (a) Schematic showing the different contributions of water-level changes that make up the total rise in water elevation. (b) Storm surge simulations, including the wave effect, due to radiation stress for steep (top), mild (centre) and shallow (bottom) bottom slopes defined by A, and for wind speeds covering gale (17.5 m/s), tropical storm (26 m/s) and hurricane (33 m/s) force. The simulations show that for steep slopes (top panel), the waveinduced water level rise (dark blue) dominates the wind-driven storm surge effect (light blue). On the contrary, for gentle slopes (bottom), the wind-induced storm surge (light blue) causes the largest water level rise rather than the waves. The yellow boxes represent the results of total storm surge when the wind-driven and wave induced water levels are added nonlinearly within the model, while the brown boxes shows the linear combination of these. Figure taken from Graber et al (2006)

Figure 9.10Example of a version of CoastTool we developed in a spreadsheet. This makes a

good testing platform for the formula.


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single example. The design tool will be able to undertake this analysis for all of the Indian coast and the beaches when fully completed. Notably, for the very moderate conditions adopted in the spreadsheet (i.e. significant wave height of 2 m and zero coastal currents, gyres, Coriolis set-up etc.) that the predicted design water level is 2.07 m above the high tide level. Note also that the climate change sea level rise is set to just 0.5 m. If the significant wave height is increased to 4 m (a moderate wave condition in a storm), then the design level becomes 4.03 m above high tide.

In the guidelines, we have taken the design level to be 2.6 m as a general assumption. This value will vary with location in India and with climate variable values once our analysis is completed and further data is collected around Indian beaches to validate the scientific equations in the design tool.

References

Graber, H.C., V.J. Cardone, R.E. Jensen, D.N. Slinn,S.C. Hagen, A.T. Cox, M.D. Powell, and C. Grassl., 2006. Coastal forecasts and storm surge predictions for tropical cyclones. A timely partnership program,Oceanography Vol. 19(1):130–141

Sanil Kumar V, Pathak, K.C., Pednekar, P., Raju, N.S.N. and Gowthaman, R., 2006. Coastal processes along the Indian coastline, Current Science, Vol. 91(4) :530-536.

Shenoi, S.S.C., Saji, P.K.and AM Almeida, A.M., 1999.Near-surface circulation and kinetic energy in the tropical Indian Ocean derived from Lagrangian drifters,Journal of Marine Research, Vol.57 :885–907

Bagnold, R.A. ,1963. Mechanics of Marine Sedimentation, in: The Sea, Vol. 3, p. 507-528, edited by M.N. Hill, Interscience, NY

Black, K.P., 1978. Wave transformation over a coral reef, Master of Science thesis undertaken at the University of Hawaii, University of Melbourne. 240 pp.

Black, K.P., 1992. The dynamics of Port Phillip Bay and adjacent Bass Strait, Victorian Institute of Marine Sciences Report for the Port Phillip Bay Model Consortium, Victorian Institute of Marine Sciences Technical Report No. 18., 120 pp.

Black, K.P. and Mathew, J., 2015. Puducherry Beach Restoration: Task 1 Feasibility Studies For Design Alternatives. Report submitted to National Institute of Ocean technology (NIOT), Chennai, India, September 2015, pp 270

Bodge, K. R., and Kraus, N. C., 1991.Critical examination of longshore transport rate magnitude, Proceedings Coastal Sediments '91, ASCE Press, New York, 139-155.

Graber, H.C., V.J. Cardone, R.E. Jensen, D.N. Slinn,S.C. Hagen, A.T. Cox, M.D. Powell, and C. Grassl. 2006. Coastal forecasts and storm surge predictions for tropical cyclones, A timely partnership program,Oceanography,19(1):130–141

Kamphuis, J.W., 2000. Introduction to Coastal Engineering and Management, World Scientific Publishing Company Pte Ltd., 437 pp.

Kamphuis, J.W., 1991. Alongshore sediment transport rate, Journal of Waterway, Port, Coastal and Ocean Engineering, Vol. 117, 624-640

Lee, T.T. and Black, K.P., 1978.The energy spectra of surf waves on a coral reef, Proceedings of the 16th International Conference on Coastal Engineering (ASCE), Hamburg.pp.588-608.

Middleton, J.F. and Black, K.P., 1994. The low frequency circulation in and around Bass Strait: a numerical study, Continental Shelf Research, 14(13/14): 1495-1521.


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Mil-Homens, J., Ranasinghe, R., Van Thiel de Vries, J.S.M. and Stive, M.J.F., 2013. Re-evaluation and improvement of three commonly used bulk longshore sediment transport formulas, Coastal Engineering 75, 29-39

SPM, 1984. Shore Protection Manual, US Army Coastal Engineering Research Centre, Waterways Experiment Station, Vicksburg Miss., US Army Corps of Engineers, USA.

Van Rijn, L.C., 1990, 2011. Principles of fluid flow and surface waves in rivers, estuaries and coastal seas, Aqua Publications, Nederland (www.aquapublications.nl)

Van Rijn, L.C., 1993, 2006. Principles of sediment transport in rivers, estuaries and coastal seas, Aqua Publications, Netherlands

Van Rijn, L.C., 1997. Sediment transport and budget of the central coastal zone of Holland, Coastal Engineering, Vol. 32, 61-90

Van Rijn, L.C., 2002. Longshore transport, 28th ICCE, Cardiff, UK, 2439-2451

Van Rijn, L.C., 2006, 2012. Principles of sedimentation and erosion engineering in rivers, estuaries and coastal seas.Aqua Publications, The Netherlands (www.aquapublications.nl).

Vijayakumar, G., Rajasekaran, C., Sundararajan, T and Govindarajalu, D., 2014. Studies on the dynamic response of coastal sediments due to natural and manmade activities for the Puducherry coast, Indian Journal of Marine Sciences, Vol. 43(7), July 2014.

http://www.aquapublications.nl/


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10. ENVIRONMENT IMPACT AND ECONOMIC ANALYSIS

10.1 PART 1: ENVIRONMENTAL IMPACT ASSESSMENT (EIA)

10. 1. 1 INTRODUCTION

Environmental Impact Assessment (EIA) is a tool that seeks to ensure sustainable development through the evaluation of those impacts arising from a major activity (policy, plan, program, or project) that are likely to have significant environmental effects. EIA systematically examines both beneficial and adverse consequences of the project and ensures that these effects are taken into account during project design. It helps to identify possible environmental effects of the proposed project, proposes measures to mitigate adverse effects and predicts whether there will be significant adverse environmental effects, even after the mitigation is implemented. By considering the environmental effects of the project and their mitigation early in the project planning cycle, environmental assessment has many benefits, such as protection of environment, optimum utilization of resources and saving of time and cost of the project. Properly conducted EIA also lessens conflicts by promoting community participation, informing decision makers, and helping lay the base for environmentally sound projects. Benefits of integrating EIA have been observed in all stages of a project, from exploration and planning, through construction, operations, decommissioning, and beyond site closure.

EIA is intended to prevent or minimize potentially adverse environmental impacts and enhance the overall quality of a project. The main benefits and advantages of EIA are:

Lower project costs in the long-term

Increased project acceptance

Improved project design

Informed decision making

Environmentally sensitive decisions

Increased accountability and transparency

Reduced environmental damage

Improved integration of projects into their environmental and social settings

The climate change adaptation guidelines require the coastal protection project to prepare a full Environmental Effects Statement (EES) including climate change impacts before any construction approvals are given. The guidelines emphasize that the design must be site specific and based on a clear understanding of the coastal processes, the long-term stability or instability of the coast and the ecological impacts. A comprehensive EIA based on long term monitoring has been recommended. This appendix provides the basic requirements for the preparation of EIA and EMP.

For the EIA process, the Ministry of Environment, Forests and Climate Change (MoEF&CC) has promulgated EIA notification in 1994 under the Environment (Protection) Act (1986) making environment clearance mandatory for setting up new projects listed therein. The detailed Notification and the guidelines for EIA approval process is available in www.moef.nic.in/environmental_clearancegeneral


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10. I. 2THE EIA PROCESS

The basic objectives for EIA are to predict environmental impact of projects, find ways and means to reduce adverse impacts and shape the projects to suit local environment.

An EIA is expected to cover at least the following matters:

Description of the proposed activities;

Description of the base environmental and climatic conditions and potential affected environment including specific information necessary to identify and assess the environmental effect of the proposed activities;

Analysis of the land use and land use change, waste generation, water consumption (and the existing balance), power consumption etc. along with the social and health impacts (in terms of number of people displayed etc);

Description of the practical activities as appropriate;

An assessment of the likely or potential environmental impacts of the proposed activity (like air pollution, noise generation) and the alternatives, including the direct or indirect, cumulative, short-term and long-term effects;

A risk assessment report and disaster management plan to mitigate adverse environmental impacts of proposed activity and assessment of those measures;

An indication of the likely area to be affected by the proposed activity or its alternatives;

A detailed environmental feasibility report.

Project Proposal, Scoping and Consideration of Alternatives

Preparation of a project proposal is the first step. The project proposal shall include all relevant information available including a land-use map. Scoping is a process of detailing the terms of reference of EIA. Quantifiable impacts are to be assessed on the basis of magnitude, prevalence, frequency and duration and non-quantifiable impacts (such as aesthetic or recreational value), significance is commonly determined through the socio-economic criteria. After the areas where the project could have significant impact, are identified, the baseline status of these should be monitored and then the likely changes in these on account of the construction and operation of the proposed project should be predicted. Baseline data describes the existing environmental status of the identified study area. The site-specific primary data should be monitored for the identified parameters and supplemented by secondary data if available.

Impact Prediction and Assessment of Alternatives

Impact prediction is a way of mapping the environmental consequences of the significant aspects of the project and its alternatives. For every project, possible alternatives should be identified and environmental attributes compared. Alternatives should cover both project location and process technologies. Alternatives should then be ranked for selection of the best environmental and optimum economic benefits for the community at large. Once alternatives have been reviewed, a mitigation plan should be drawn up for the selected option and is supplemented with an Environmental Management Plan (EMP) to guide the proponent towards environmental improvements. The EMP is a crucial input to monitoring the clearance conditions and therefore details of monitoring should be included in the EMP.

The EIA Report

An EIA report should provide clear information to the decision-maker on the different environmental scenarios without the project, with the project and with the project alternatives. The detailed Project report provides information in logical and transparent manner.


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Monitoring has to be clearly spelt out for both construction and operation phases of a project. It‘s not done just to ensure that the commitments made are complied with, but also to observe whether the predictions made in the EIA reports are correct or not. Where the impacts exceed the predicted levels, corrective action should be taken. Monitoring also enables the regulatory agency to review the validity of predictions and the conditions of implementation of the Environmental Management Plan (EMP). The generic structure of EIA report is condensed in the Table 10.1.1.

Table 10.1.1 Generic structure of the EIA report

No. EIA structure Contents

1. Introduction o Purpose of the report o Identification of project & project proponent o Brief description of nature, size, location of the

project and its importance to the country, region o Scope of the study – details of regulatory scoping

carried out (as per terms of reference)

2. Project description Condensed description of those aspects of the project (based on project feasibility study), likely to cause environmental effects. Details should be provided to give clear picture of the following:

o Type of project o Need for the project o Location (maps showing general location, specific

location, project boundary & project site layout) o Size or magnitude of operation (including

associated activities required by or for the project) o Proposed schedule for approval and

implementation o Technology and process description o Project description including drawings showing

project layout, components of project etc. Schematic representations of the feasibility drawings which give information important for EIA purpose.

o Description of mitigation measures incorporated into the project to meet environmental standards, environmental operating conditions, or other EIA requirements (as required by the scope)

o Assessment of new & untested technology for the risk of technological failure

3. Description of the environment

o Study area, period, components & methodology o Establishment of baseline for valued environmental

components, as identified in the scope o Base maps of all environmental components

4. Anticipated environmental impacts & mitigation measures

o Details of investigated environmental impacts due to project location, possible accidents, project design, project construction, regular operations, final decommissioning or rehabilitation of a completed project

o Measures for minimizing and / or offsetting adverse impacts identified

o Irreversible and irretrievable commitments of


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environmental components o Assessment of significance of impacts (criteria for

determining significance, assigning significance) o Mitigation measures

5. Analysis of alternatives (technology & site)

In case, the scoping exercise results in need for alternatives:

o Description of each alternative including the results of the model studies

o Summary of adverse impacts of each alternative o Mitigation measures proposed for each alternative

and o Selection of alternative

6. Environmental monitoring program

Technical aspects of monitoring the effectiveness of mitigation measures (including measurement methodologies, frequency, location, data analysis, reporting schedules, emergency procedures, detailed budget & procurement schedules)

7. Additional studies o Public consultation o Risk assessment o Social impact assessment; R&R action plans

8. Project benefits o Improvements in the physical infrastructure o Improvements in the social infrastructure o Employment potential–skilled; semi-skilled and

unskilled o Other tangible benefits

9. Environmental Cost - Benefit analysis

If recommended at the scoping stage

10. EMP

Description of the administrative aspects of ensuring that mitigative measures are implemented and their effectiveness monitored, after approval of the EIA

11 Summary & Conclusion (this will constitute the summary of the EIA Report )

o Overall justification for implementation of the project

o Explanation of how, adverse effects have been mitigated

12. Disclosure of consultants engaged

The names of the consultants engaged with their brief resume and nature of consultancy rendered

10. 1. 3 EIA PROCESS IN INDIA

On 27th January 1994, Union Ministry of Environment & Forests, GOI under Environment (Protection) Act 1986, promulgated EIA notification making Environment clearance mandatory for expansion or modernization of any activity or for setting up new projects listed in Schedule one of the notification, which have been amended more than12 times.

In India, EIA was made mandatory in 1994 with the following four objectives:

a) Predict environmental impact of projects;

b) Find ways and means to reduce adverse impacts;

c) Shape the projects to suit local environment;

d) Present the predictions and options to the decision-makers.

Till 1994, EIA clearance was the administrative requirement for big projects undertaken by the Government or public sector undertakings. The Notification mandates a public hearing


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and environment itself), with further review by a committee of experts in certain cases. According to Schedule II of the notification, the EIA is expected to cover at least the following matters:

a) Description of the proposed activities; b) Description of the base environmental and climatic conditions and potential affected

environment including specific information necessary to identify and assess the environmental effect of the proposed activities

c) Analysis of the land use and land use change, waste generation, water consumption (and the existing balance), power consumption etc. along with the social and health impacts (in terms of number of people displayed etc)

d) Description of the practical activities as appropriate e) An assessment of the likely or potential environmental impacts of the proposed

activity (like air pollution, noise generation) and the alternatives, including the direct or indirect, cumulative, short-term and long-term effects;

f) A risk assessment report and disaster management plan to mitigate adverse environmental impacts of proposed activity and assessment of those measures;

g) An indication of the likely area to be affected by the proposed activity or its alternatives;

h) A detailed environmental feasibility report of all the information provided.

10. I. 4 PROJECTS SUBJECT TO EIA The projects can be classified into three categories based on whether EIA is required or not and who is responsible for the clearance. Category 1: Projects where EIA is mandatory and requires clearance from Central government As of now, EIA clearance is required for 30 categories of industries from the central government which can be broadly categorized under sectors of industries, mining, thermal power plants, river valley, ports, harbours and airports, communication, atomic energy, transport (rail, road, highway), tourism (including hotels, beach resorts)

Category 2: Projects where EIA is mandatory and requires clearance from State Governments (full EIA may not be required) The Central Government has notified (dated 10 April 1997, No. S. O.319. E) that certain category of thermal power plants namely all capacity cogeneration plants, captive coal and gas/naphtha based power plants up to 250 MW, coal based power plants up to 250 MW using conventional technologies, coal based plants up to 500 MW using fluidized bed technology and gas/naphtha based plants up to 500 MW require environmental clearance from the state government. In case of pithead thermal power plants, the applicant shall intimate the location of the project site to the state government while initiating any investigation and surveys. Proposals where forestland is a part of the project site need prior forestry clearance before forwarding to MoEF for environmental clearance. In the environmental clearance process, the documents to be submitted to MoEF are project report, public hearing report, site clearance for site specific projects, no objection certificate from State Pollution Control Board (SPCB), environmental appraisal questionnaire, EIA/EMP report, risk analysis for projects involving hazardous substance and rehabilitation plans, if more than 1000 people are likely to be displaced. Category 3: For these projects EIA is not necessary: Some of the projects that come under this category include defense related road construction projects in border areas, production of production of bulk drugs based on genetically engineered organisms: Construction activities related to the projects of Department of Atomic Energy (b) laying of pipelines, conveying systems including transmission lines; (c) facilities that are essential for activities


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permissible under CRZ-I; Exploration and extraction of oil and natural gas is also permitted between Low Tide Line (LTL) and High Tide Line (HTL) in areas, which are not ecologically sensitive, pipeline projects; Facilities for receipt and storage of Liquefied Natural Gas (LNG) and facilities for its re-gasification.

10. I. 5THE EIA PROCEDURE The EIA process in India consists the following phases:

Project Proposal: Any proponent embarking on any major development project shall notify IAA in writing by the submission of a project proposal. The project proposal shall include all relevant information available including a land-use map in order for it to move to the next stage, which is screening. The submission of a project proposal signifies the commencement of the EIA process.

Screening: Screening is done to see whether a project requires environmental clearance as per the statutory notifications. At this stage, the project proponent decides the type of project and also about requirement of Environmental Clearance. If required, the proponent may consult IAA.

Scoping and consideration of alternatives: Scoping is a process of detailing the terms of reference of EIA. It has to be done by the consultant in consultation with the project proponent and guidance, if need be, from Impact Assessment Agency. The Ministry of Environment and Forests has published guidelines for different sectors (see next sub section), which outlines the significant issues to be addressed in the EIA studies. Quantifiable impacts are to be assessed on the basis of magnitude, prevalence, frequency and duration and non-quantifiable impacts (such as aesthetic or recreational value), significance is commonly determined through the socio-economic criteria. After the areas, where the project could have significant impact, are identified, the baseline status of these should be monitored and then the likely changes in these on account of the construction and operation of the proposed project should be predicted

Base line data collection: Base line data describes the existing environmental status of the identified study area. The site-specific primary data should be monitored for the identified parameters and supplemented by secondary data if available.

Impact prediction and Assessment of Alternatives: Impact prediction is a way of mapping the environmental consequences of the significant aspects of the project and its alternatives. For every project, possible alternatives should be identified and environmental attributes compared. Alternatives should cover both project location and process technologies. Alternatives should then be ranked for selection of the best environmental optimum economic benefits to the community at large. Once alternatives have been reviewed, a mitigation plan should be drawn up for the selected option and is supplemented with an Environmental Management Plan (EMP) to guide the proponent towards environmental improvements. The EMP is a crucial input to monitoring the clearance conditions and therefore details of monitoring should be included in the EMP.

EIA Report: An EIA report should provide clear information to the decision-maker on the different environmental scenarios without the project, with the project and with project alternatives. The proponent prepares detailed Project report and provides information in logical and transparent manner. The IAA examines if procedures have been followed as per MoEF notifications.


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Public hearing: After the completion of EIA report the law requires that the public must be informed and consulted on a proposed development after the completion of EIA report. The State Pollution Control Boards will conduct the public hearing before the proposals are sent to MoEF for obtaining environmental clearance. Any one likely to be affected by the proposed project is entitled to have access to the Executive Summary of the EIA. The affected persons may include: a) Bonafide local residents; b) Local associations; c) Environmental groups: active in the area; d) Any other person located at the project site / sites of displacement. They are to be given an opportunity to make oral/written suggestions to the State Pollution Control Board as per Schedule IV.

Decision-making: Decision making process involve consultation between the project proponent (assisted by a consultant) and the impact assessment authority (assisted by an expert group if necessary). The decision on environmental clearance is arrived at through a number of steps including evaluation of EIA and EMP.

Monitoring the clearance conditions: Monitoring has to be done during both construction and operation phases of a project. It is done not just to ensure that the commitments made are complied with but also to observe whether the predictions made in the EIA reports are correct or not. Where the impacts exceed the predicted levels, corrective action should be taken. Monitoring also enables the regulatory agency to review the validity of predictions and the conditions of implementation of the Environmental Management Plan (EMP). The Project Proponent, IAA and Pollution Control Boards should monitor the implementation of conditions. The proponent is required to file once in six months a report demonstrating the compliance to IAA.

10.2 PART2: ECONOMIC ANALYSIS

10. 2. 1 INTRODUCTION

Coastal protection projects have both direct and indirect or hidden costs and benefits. The direct costs relate to the initial project capital development cost of the works, i.e. the direct cost of building a coastal intervention, and the ongoing operation and maintenance costs over the life of project, for example the cost of the periodic nourishment of the beach. The hidden costs relate to unforeseen downstream impacts or the need for unforeseen maintenance, e.g. the cost of repairing a downstream beach impacted by the works, or the maintenance arising when rocks used in the project are dislodged by waves. Over the full life cycle of a project, it may be cost effective to use larger rocks at the start rather than accepting long-term maintenance.

Direct benefits relate to the value of assets protected by the coastal work, like land, houses and roads. The indirect benefits may be elements such as improved access to the beach for fishing, impact on public health, tourism or development of coastal resorts for income generation, protection of cultural heritage etc.

In India, the costing of projects for coastal protection generally has only considered the direct costs. There has been no attempt to analyse the hidden costs and no specific consideration of both direct and hidden benefits over the whole life of the project. While a seawall may be built to protect houses, no calculations are done to estimate the value of those houses being protected, or to examine the total cost compared with the benefits of the project. Many of the decisions to protect a coast have arisen from residents applying political pressure to local politicians or engineers planning works which they believe to be worthwhile, but are not subject to a cost benefit analysis.

This lecture note contains how to undertake:


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Full life-cycle costing of a project, that is allowing for all costs of a project including for the initial capital costs of construction, the ongoing maintenance and replenishment costs and the costs of negative external impacts downstream or outside of the project;

Identifying and quantifying the benefits resulting from the project over its full life, including methods of valuing benefits that are not easily expressed in monetary values; and

The application of Cost-Benefit Analysis to indicate if a project is economically viable and to allow the comparison of project relative economic performance through the indicator of the Internal Rate of Return (IRR), Net Present Value (NPV) and Benefit: Cost Ratio (BCR) .

10.2.2 COST BENEFIT ANALYSIS

Economists and planners use Cost Benefit Analysis (CBA) to help decide if a project is economically viable and worthwhile investment. In relation to these Guidelines, the goal of the economics is to ensure the following:

Development of a CBA model that accounts for all economic, environmental and social costs and benefits of coastal management strategies.

Enable planners to use the CBA model to rationalize the allocation of resources, and to make decisions about the appropriate strategy for sites. The development of interventions in order to ensure the most efficient allocation and beneficial use of capital resources in the coastal zone for the management and adaptation to coastal erosion and the future impact of climate change

Cost Benefit Analysis (CBA) uses full life cycle cost analysis, not just construction costs, which incorporates on-going maintenance, environmental restoration costs, downstream impacts and other costs that may arise due to the structure over its full life-cycle of thirty years or more. Similarly, the benefits of environmental beach restoration and coastal protection that occur over the full life-cycle to offset costs are valued and included in the evaluation, e.g. protection of infrastructure, land, agriculture and fisheries livelihoods, public amenities, tourism, social and historical features, etc.

Methodologies for including subsistence and non-market values, ecological functions and non-use benefits in the economic valuation of benefits are considered. The Appendix also highlights issues concerning the appropriate discount rate, valuation of benefits and costs, inter-generational equity, direct values, indirect values, option values and non-use values, etc.

Cost-benefit analysis (CBA) is used to assess the economic performance of a project over its life and to allow comparison of the economic return of different projects as a means of assessing the priority for implementation. When capital is limited, as is likely to be the case for developing coastal protection measures when the effects of SLR and CC become more apparent, it will be necessary to direct the investment to projects where the economic benefits are highest.

The basis for CBA is that the future annual cash flows of costs (capital and maintenance) will be less than the benefits.

To put all projects on a level playing field for comparison, many economists will adjust the costs and benefits to Present Value, i.e. future costs and benefits are adjusted to today‘s financial conditions. This is done because the money spent in the future has a different value (due to inflation, interest and the loss of future alternative uses of the money being used for


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the project). The adjustment is done using a ―discount rate‖ which is a percentage change in the value of the money. The simplest approach for choosing the discount rate is to decide the rate which the capital needed for the project could return if invested in an alternative venture. If, for example, the capital required for Project A can earn 5% elsewhere, use this discount rate in the Present Value calculation to allow a direct comparison to be made between Project A and the

alternative.

Usually international development agencies (IDAs), such as the World Bank and Asian Development Bank, require that the discount rate should be 10% to 12% representing the opportunity cost of capital.

Table 10.2.1 Recommended discount rates for Indian beach protection projects.

Methodology Discount rate Comment

Nourishment 1% Long-lived and beneficial for the full sediment cell

Offshore reefs 3% Widen the beach and sediment is stored in the salient

Offshore breakwaters 5% Requires more maintenance

Low-crested groynes 8% Can only slow sediment losses

Groynes 10% Needs maintenance and might impact on downstream beaches

Seawalls 20% Beach is lost. Long term costs are high

However for projects, such as those building resilience to climate change and protecting the environment, with a longer gestation period before the full benefits are achieved and longer time-scales with inter-generational aspects to be considered, a lower discount rate, e.g. 5%, is generally considered to be more realistic. For Indian coastal protection projects, we recommend the following discount rates in Table 10.2.1.

Project economic performance can be measured by the Benefit Cost Ratio (BCR), which is the ratio between the PV of benefits and the PV of costs. A BCR of greater than 1.0 results when the PV of benefits is greater than the PV of costs and is often used as the indicator of a satisfactory economic performance.

Benefit Cost Ratio: For a simple economic analysis used as an initial screening instrument and to indicate the likely economic performance, the Benefit Cost Ratio (BCR) is a convenient means of assessing project viability. The PV of a constant stream of costs or benefits over a time period (PV of an annuity) can be expressed by multiplying the yearly amount by a common factor (the ―annuity factor‖), which depends on the discount rate that is applied, as illustrated in Table 10.2.1.

For example, an expenditure of $1000 over 30 years would have a Present Value reduced by 25.8%, i.e. $742.

Table 10.2.2 PV of Annuity Factor according to Discount Rate

Discount rate PV of Annuity Factor 20 years 30 years 50 years

10% 8.5 9.4 9.9 7% 10.6 12.4 13.8 5% 12.5 15.4 18.3 1% 18.0 25.8 39.2


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10.2.3 ASSESSING COSTS

Assessing the costs is the easier part of preparing a Cost Benefit Analysis. Coastal protection project costs are made up of the initial capital investment costs and the ongoing Operational and Management costs needed to maintain the assets that occur over the life of the project. The capital costs are defined during project preparation and typically will be incurred over the first years of project implementation, which for coastal protection projects can be expected to be implemented over a one to three year time frame depending on the size and complexity of the project.

The capital costs as they occur can be expressed as a Present Value by using a discount factor for each year and summed to represent the total Present Value of capital costs. The Present Value factors for various discount rates for years 1 to 5 are shown in Table 10.2.3.

Table 10.2.3 PV Factor for Years 1-5 according to Discount Rate

Year Discount Rate

1% 5% 7% 10%

1 0.990 0.952 0.935 0.909

2 0.980 0.907 0.873 0.826

3 0.971 0.864 0.816 0.751

4 0.961 0.823 0.763 0.683

5 0.951 0.784 0.713 0.621

Annual O&M costs can be expressed as a percentage of the initial capital cost, and vary according to the category of costs. Hard assets such as roads, seawalls, and buildings typically have annual O&M of between 0.5% to 3% of the initial capital cost, while equipment and moveable assets such as pumps, control gates have a higher rate – 5% to 10% of their capital cost per year. Vehicles have a higher annual cost of maintenance and fuel, proportional to the amount of usage. O&M costs can be regarded as an annuity, i.e. a constant amount occurring every year and can be converted to a PV by the appropriate PV of an annuity factor as noted above.

Some operation and maintenance costs occur as irregular lumps every so many years over the life of the project, for example the replenishment of sand every five years, or major repairs to protection infrastructure that may be required after an exception storm or climatic event. In this case the irregular amounts can be averaged to a yearly cost and the PV calculated through the PV of annuity tables, or more simple calculated from the cash flow in Excel.

Sometimes the introduction of protection measures in one location may have an unintended negative impact on another location off-site, for example, when the construction of an artificial reef to protect an area of coastline may change the morphology of another location leading to accelerated beach erosion. The impact of this should be included as a cost, or negative benefit, of the project.

10.2.4 ASSESSING BENEFITS

Assessing the benefits arising from coastal protection measures is a more complicated and diverse exercise than assessing the costs. Coastal protection projects are designed to protect the coast and increase resilience to climatic events. Most of the benefits are in the form of saved losses: saving the loss of land due to coastal erosion, prevention of the destruction of roads and infrastructure, protecting land from losses in productivity due to salt water intrusion, and so on. Assessing the benefits requires both information about the likely impacts (saved loss) and the timing of when the loss may occur over the life of the project.


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Both of these aspects require local knowledge of the extent of the coastal land and infrastructure affected and detailed analysis of the impacts supported by field investigation. The likely benefits can be divided into seven categories as given in Table 10.2.4.

Table 10.2.4 Benefit categories that accrue from coastal protection measures

Benefit category Description

1. Loss of land Physical loss of coastal land due to coastal erosion

2. Loss of land productivity

Loss of agricultural production from coastal land due to inundation with sea water and saline water intrusion

3. Damage to assets Damage and destruction of coastal assets including housing, buildings, roads, port facilities due to coastal erosion

4. Loss of livelihood Impact on local fishing activities, tourism due to the loss of the beach and assess to boat launching facilities

5. Saved protection costs in without project situation

Savings in the cost of emergency and remedial works that would have to be incurred if the project did not exist

6. Increase in economic output

Impact of coastal protection measures on promoting economic activity such as investment in tourism infrastructure, intensified agricultural production

7. Impact on cultural and heritage sites

Damage and destruction to cultural assets, such as places of worship, heritage buildings, graveyards etc through coastal erosion

A first step in the benefit assessment is to define the boundaries and extent of the land that is affected and that will be protected through the project. This land may be divided into the beach frontage that has no economic use other than providing protection to the back slope, a desirable location for tourist operations, and to provide access to the sea for fishing. Then there is land that is used for infrastructure and housing close to the beach, and thirdly productive land that is used for agriculture and which will be threatened by coastal erosion. Quantifying these benefits required an estimate of the annual net production from the land and the loss in income through the impact on its use, or the need to change to a less productive use.

Quantifying the saved cost of damage to assets (category 3) requires an estimation of the saved cost of the repairs, and a valuation of the replacement cost in the event that the asset is destroyed. In extreme case, the local residents may have to relocate to a location in which case there will be the cost of establishing a new home. Relocation may also lead to a loss of livelihood and the need to take up an alternative livelihood, as would be case when coastal residents are no longer able to work as fishermen. The net loss in their livelihood can then be counted as a benefit.

The installation of an effective coastal protection measures means that there will be a saving in the costs that would have been incurred in the without project situation in dealing with emergencies to protect essential infrastructure and remedial works. The saving in this cost can also be counted as a benefit in the CBA. This requires the analyst to estimate what the annual average costs of protection would be without the project, and how effective this work might have been in protecting the coastline.

Effective coastal protection measures can act as a stimulus for increased economic production in the coastal area when investors and landholders have more confidence to develop resources for tourism and more intensive agricultural production. The net increase in national tourism can be counted as a benefit to the economy, i.e. an increase in international tourism rather than a relocation of tourists from another tourist area. Coastal


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protection interventions can also enhance people‘s livelihoods and resilience to natural disasters in a positive way, not only through the avoided costs of damage. The benefits of these types of projects can be valued as the increase in income, or income-in-kind over the life of the project.

The coastal protection works may also protect locations and infrastructure with a particular cultural and heritage value that cannot be easily expressed in monetary terms, such as the case for the destruction of a building, or loss of productivity from land. The value of the saving of these assets can also be included as a benefit, but they usually require other techniques to arrive at their value to the society.

10.2.5ASSESSING WHEN BENEFITS OCCUR

The next step after defining the type and monetary value of the benefits is to decide when the benefits will occur over the life of the project. In the situation without the coastal protection provided by the project there will be annual accumulation of impacts as the coastal land is eroded away and productive land is subject to more frequent inundation with seawater. In most of India's coastal erosion occurs during the annual monsoon period when increase storms and rainfall cause heightened wave action and flooding in coastal areas contributing to an gradual landward progression of the coastline. Unlike other situations where coastal erosion is caused by extreme climatic events such as a cyclone the situation in India is a more gradual annual process. In this case, the analyst must estimate the extent of the land loss and associated damage and impact on economic activity each year over the life of the project. This should also allow for the partial protection provided in the without project situation by the unplanned and less effective coastal protection measures. The net result is an average annual benefit of the saved losses.

10.2.6PROBABILITY MATRIX

Where it is possible to ascribe a probability of occurrence of climatic events of varying severity leading to coastal erosion and its impact a probability matrix can be developed to calculate the average annual loss. The methodology for assessing the benefits of installing coastal protection measures against climatic events (sea surges, wave overtopping, flooding etc.) is to calculate the expected damage that would occur in the absence of the protective measures and to express the cost of the damage avoided as an average annual benefit over the life of the project. For example if the construction of a flood protection measure, say, ecology-based coastal protection is expected to reduce damage to an acceptable level for up to a 20-year event and the damage/cost expected in the without project situation is INR100,000, then the average benefit would be INR5,000 (100,000/20) per year, which can be discounted to a PV by applying the PV of an annuity factor. Floods with a more frequent occurrence but with a lower level of associated damage would also be included in the benefits.

Although the frequency of extreme climatic events may be able to be predicted based on the historical records, the difficulty is in estimating the costs of the damage resulting from an event. This is dependent on the value of the infrastructure that is being protected by the protective measures, and the expected damage that would occur to the assets related to the severity of the storm/event. The amount of damage usually depends on the depth and amount of time the location might be inundated, and the destructive force of the flooding and wind that occurs with an extreme climatic event destroying property and eroding the land. As noted above, predicting and quantifying the costs (benefits) requires a valuation of the assets and an assessment of the likely cost of the damage to property, personal injury, livelihoods etc., which usually requires intensive field investigation for each situation and project.


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The probability of events with different return periods and their associated costs can be developed to show an overall annual average cost/saved damage cost as illustrated in Table 10.2.5, which relates storm severity to its associated cost of damage. The risk of a 5-year storm happening in any year is 1/5 = 0.2, a 10 year storm has an annual risk of 1/10 = 0.1 and so on. The risk of a storm which is greater than a 5-year storm but not as great as a 10-year storm is 1/5 – 1/10 = 0.1. Similarly a storm greater that 10 years but not greater than 20 years is 1/10 -1/20 = 0.05. The sum of all the probabilities of the events is 1.00.

Table 10.2.5 Average Annual Avoided Costs Example

Return period Years and Storm

Probability Range

Annual

Probability

Associated

damage

Average

annual

cost

<5 Storm less than 1:5 year 0.80 1,000 800

5-10 Storm greater or equal to 1:5

but less than 1:10

0.10 15,000 1,500

10-20 Storm greater or equal to

1:10 but less than 1:20 year

0.05 400,000 20,000

>20 Storm of 1:20 or greater 0.05 1,500,000 75,000

Total annual average cost 1.00

The impact and cost of damage usually are proportionally much greater as the return period increases. The probability of damage from a 5 to 10 year storm is 0.10, and the damage cost if it occurs is $15,000, so the cost on average each year is 0.1 x $15,000 = $1,500. If for example a protective measure were able to provide protection up to a 20-year storm then the annual average benefit of the cost savings would be $22,300. As the protective measures do not provide protection for a storm with a return frequency greater than 20 years the average annual cost of these storms of $75,000 is not included.

Where there is a large amount of damage associated with and infrequent event this may result in a higher annual saved loss benefit than the average benefit as described in the preceding paragraphs

In most locations in south-west India, there is not sufficient information available of the occurrence and frequency of storms and extreme events and the associated level of impact and damage to build a realistic probability matrix. The impact has to be assessed through the average annual cost based on the progressive rate of annual coastal erosion.

10.2.7 ECONOMIC ANALYSIS TEMPLATE

The economic analysis and screening of coastal protection projects identified and proposed for inclusion in a programme requires a relatively simple and cost-effective methodology that can be applied by local staff who may not be skilled in economic analysis. Application of the model will assist in the screening a a number of potential projects covering a wide range a wide range of activities to whittle down the list to a short list of project, which would then be subject to a more detailed economic analysis by professional staff with capacity in the application of CBA and skills in the economics of coastal protection. Another important application of the economic model will be to evaluate between several options to achieve the same output to determine which is the most cost effective and least cost option for a particular location, called least cost analysis.


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Simple Economic Template

For relatively straight-forward projects a template could be used for the economic analysis based on a simplified Cost Benefit analysis using the Benefit Cost Ratio as the main indicator for assessing economic viability, as discussed above. The ‗B‖ side of the equation represents the avoided cost of damage under climate change. A Benefit Cost Ratio of more than 1.0 indicates that the project is economically viable. The proposed template for these types of projects is shown in Table 10.2.6.

Table 10.2.6 Economic Evaluation and Screening Template

Economic Evaluation Template for Coastal Protection Projects Project name ___________________________________ Project No.________________ Location (Village) ________________________________ Date ________________ Project description ________________________________________________________________________ _________________________________________________________________________ ________________________________________________________________________ Project Category Local Infrastructure Road/ Culvert , Seawall , Building , Community asset , Cultural asset , Relocation Ecological Beach protection , Hard structres, Mangrove planting , Reef conservation Sectoral/ Livelihoods support/ Resilience Agriculture , Fisheries , Forestry , Tourism , Other ___________________ Village Population__________ Number of Beneficiaries ______________ Project Costs (itemise the estimated costs and implementation schedule)

Item Total cost Implementation programme (% of costs)

(INR‘000) Year 1 Year 2 Year 3 Year 4

Civil works

Equipment & materials

Personnel

Training

Other

TOTAL INVESTMENT

O&M Costs (Estimate the annual O&M costs for the project)

Item % of cost Annual cost

Civil works 1%

Equipment 10%

Sand replenishment (ave/yr)

Other 5%

Total O&M per year

Project Benefits (List the expected impact/ benefits of the project. Expand as necessary)

Item Impact Value INR‘000

Value of assets affected (Housing, roads, buildings, tree crops etc)


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Estimated average annual value of avoided damage

(Based on degree of protection and return period for destructive events)

Estimated average annual value of improved production/ livelihoods

(Value of production from agriculture, fisheries, forestry, tourism resulting from the project)

Benefit Cost Ratio (based on discount rate of 5% and 30 year project life)

COSTS Total

Investment Costs (from above adjusted for timing)

O&M (as above) PV = Annual value times 15

TOTAL (A)

BENEFITS Total

Avoided damage PV = Annual average value x 15

Livelihood Benefits PV = Annual average value x15

TOTAL (B)

BENEFIT COST RATIO B:C Ratio

Benefits (B) ÷ Costs (A)

Benefits

Costs

CONCLUSION/ RECOMMENDATION

Excel-based Template

For more complex projects, and where there is greater range of potential coats and benefits an economic analysis template model which uses MS Excel to derive the ERR and BC ratio could be used. This has the advantage that it is more flexible and can be adapted to capture a variety of benefits flows which may not be regular over the life of the project making it more difficult to analyse using the discount factors. An example of this type of template is shown in Table 10.2.7.

The template can be adapted to include any number of types of benefit cash flows over the life of the project, and will also calculate the sensitivity of the results to changes in the main parameters and assumptions.

The application of this type of template would usually entail a more detailed and through economic evaluation than that needed for the simpler screening template. The analyst will need more capacity and experience in the application of CBA. It could be used after the initial screening to prepare a more detailed evaluation of a short-list of projects as part of due


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diligence for getting approval for funding. It would usually require more data analysis and field investigation to substantiate and quantify the costs and benefits.

10.2.8 NOT QUANTIFIED COSTS AND BENEFITS

Mainstream economic analysis has tended to use a narrow definition of the costs and benefits, ignoring many of the other negative and positive impacts associated with a project, (also called externalities). For some projects, there are significant impacts of coastal erosion that are not easily expressed in monetary values and included in a conventional CBA. For example, when a coastal protection project may protect assets of high cultural and historical worth, but for which it is not possible to easily quantify in monetary terms. In this situation economists may apply a broader economic evaluation taking account other factors in the environment. The essence of an environmental economic evaluation is that it goes beyond outputs (as measured in the marketplace) and also considers non-market values.

The concept of total economic value has become more widely accepted; using tools for identifying and categorising all ecosystem benefits instead of focussing only on the direct natural resource, or commercial values. It also values the subsistence and non-market values, ecological functions and non-use benefits. Thus it presents a more complete picture of the economic importance of ecosystems and demonstrates the often high and wide-ranging economic costs associated with degradation, which extends beyond the loss of direct use values. It tries to express in economic ($ values) terms the importance of other values which is not captured in a conventional or traditional economic analysis. This allows a more common framework for comparison and places a value of assets that otherwise may not be properly valued.

The total economic value of an ecosystem can be categorised into four components: direct values, indirect values, option values and non-use values, as is shown in Figure 10.2.1.

Direct Values Indirect Values Option Values Non-Use Values

Production and consumption

goods such as: Water, Fish, Firewood,

Materials, Wild Foods, Crops, Pasture, Fruit,

Transport, Recreation …etc…

Ecosystem functions and services such

as: Water quality

and flow, Water storage and recharge, Nutrient

recycling, Flood attenuation,

Micro-climate …etc...

Premium placed on possible

future uses and applications

such as: Agricultural,

Industrial, Leisure, Pharmaceutical,

Water use ...etc…

Intrinsic significance of resources and ecosystems in

terms of : Cultural value,

Aesthetic value, Heritage value,

Bequest value …etc...

Source: Values and Rewards: Counting and Capturing Ecosystem Water Services for Sustainable Development, IUCN Water, Nature and Economic Technical paper No.1 2005.

Figure 10.2.1 Total Economic Value of Ecosystems


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Table 10.2.7 Excel-based Economic Evaluation Template

E

Coastal Protection Economic Evaluation Template

Capital O&M Base Investmt O&M Infrastr. Ag prodtn. Livelihood Tourism

Year costs costs Total Infrastr. Housing Ag land Ag prodtn. Livelihood Tourism Total Bnft Case 10% 10% -20% -20% -20% -20%INR'000 INR'000 INR'000 INR'000 INR'000 INR'000 INR'000 INR'000 INR'000 INR'000 INR'000 INR'000 INR'000 INR'000 INR'000 INR'000 INR'000

2016 7,637 0 7,637 0 0 0 0 0 0 0 -7,637 -8,400 -7,637 -7,637 -7,637 -7,637 -8,400

2017 26,475 0 26,475 0 0 0 0 0 0 0 -26,475 -29,123 -26,475 -26,475 -26,475 -26,475 -29,123

2018 18,669 0 18,669 0 0 0 0 0 0 0 -18,669 -20,536 -18,669 -18,669 -18,669 -18,669 -20,536

2019 10,688 0 10,688 840 0 0 0 0 610 1,450 -9,238 -10,307 -9,238 -9,406 -9,238 -9,238 -10,429

2020 3,006 651 3,657 1,426 600 2,315 381 133 4,344 9,198 5,541 5,241 5,476 5,256 5,422 5,078 4,372

2021 199 1,181 1,380 1,701 600 4,647 396 133 4,344 11,821 10,441 10,421 10,323 10,101 10,321 9,512 9,552

2022 0 1,151 1,151 1,706 600 5,654 396 133 4,344 12,833 11,682 11,682 11,567 11,341 11,562 10,551 10,813

2023 0 1,912 1,912 1,711 600 7,094 396 133 4,344 14,277 12,365 12,365 12,174 12,023 12,245 10,947 11,497

2024 0 2,172 2,172 1,715 600 7,119 396 133 4,344 14,307 12,135 12,135 11,918 11,792 12,015 10,711 11,266

2025 0 2,342 2,342 1,720 600 7,143 396 133 4,344 14,336 11,994 11,994 11,759 11,650 11,874 10,565 11,125

2026 0 2,342 2,342 1,888 600 7,167 396 133 4,344 14,528 12,185 12,185 11,951 11,808 12,065 10,752 11,317

2027 0 2,342 2,342 1,892 600 7,189 396 133 4,344 14,555 12,212 12,212 11,978 11,834 12,092 10,775 11,344

2028 0 2,342 2,342 1,897 600 7,211 396 133 4,344 14,581 12,238 12,238 12,004 11,859 12,119 10,796 11,370

2029 0 2,342 2,342 1,901 600 7,233 396 133 4,344 14,606 12,264 12,264 12,030 11,884 12,144 10,817 11,395

2030 0 2,342 2,342 1,905 600 7,254 396 133 4,344 14,631 12,289 12,289 12,055 11,908 12,169 10,838 11,420

2031 0 2,342 2,342 1,909 600 7,275 396 133 4,344 14,656 12,314 12,314 12,080 11,932 12,194 10,859 11,445

2032 0 2,342 2,342 1,913 600 7,296 396 133 4,344 14,682 12,339 12,339 12,105 11,957 12,220 10,880 11,471

2033 0 2,342 2,342 1,917 600 7,318 396 133 4,344 14,708 12,365 12,365 12,131 11,982 12,245 10,902 11,496

2034 0 2,342 2,342 1,921 600 7,340 396 133 4,344 14,733 12,391 12,391 12,157 12,007 12,271 10,923 11,522

2035 0 2,342 2,342 1,925 600 7,362 396 133 4,344 14,760 12,417 12,417 12,183 12,032 12,297 10,945 11,549

2036 0 2,342 2,342 1,925 600 7,362 396 133 4,344 14,760 12,417 12,417 12,183 12,032 12,297 10,945 11,549

2037 0 2,342 2,342 1,925 600 7,362 396 133 4,344 14,760 12,417 12,417 12,183 12,032 12,297 10,945 11,549

2038 0 2,342 2,342 1,925 600 7,362 396 133 4,344 14,760 12,417 12,417 12,183 12,032 12,297 10,945 11,549

2039 0 2,342 2,342 1,925 600 7,362 396 133 4,344 14,760 12,417 12,417 12,183 12,032 12,297 10,945 11,549

2040 0 2,342 2,342 1,925 600 7,362 396 133 4,344 14,760 12,417 12,417 12,183 12,032 12,297 10,945 11,549

2041 0 2,342 2,342 1,925 600 7,362 396 133 4,344 14,760 12,417 12,417 12,183 12,032 12,297 10,945 11,549

2042 0 2,342 2,342 1,925 600 7,362 396 133 4,344 14,760 12,417 12,417 12,183 12,032 12,297 10,945 11,549

2043 0 2,342 2,342 1,925 600 7,362 396 133 4,344 14,760 12,417 12,417 12,183 12,032 12,297 10,945 11,549

2044 0 2,342 2,342 1,925 600 7,362 396 133 4,344 14,760 12,417 12,417 12,183 12,032 12,297 10,945 11,549

2045 0 2,342 2,342 1,925 600 7,362 396 133 4,344 14,760 12,417 12,417 12,183 12,032 12,297 10,945 11,549

Discount Rate @ 12% EIRR 14.12% 12.9% 13.9% 13.7% 14.0% 12.7% 12.0%

ENPV 9,477 4,496 8,534 7,591 8,875 3,187 59

Sensitivity Indicator EIRR 5.6 0.9 1.0 0.3 3.3 5.0

ENPV 5.3 1.0 1.0 0.3 3.3 5.0

Switching Value EIRR 18% 106% 103% 326% 31% 20%

ENPV 19% 100% 101% 315% 30% 20%

Net Benefit (Cost)

Benefits


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Considering the total economic value of an ecosystem, such as area given protection through coastal protection works, involves considering its full range of characteristic as an integrated system – its resource stock or assets, flows of environmental services and the attributes of the ecosystem as a whole. Broadly defined the total economic value of the ecosystem includes:

Direct values: natural resources (raw materials and physical products) which are used directly for production, consumption, and sale, such as those providing energy, shelter, food, agricultural production, fish production, water supply, transport and recreational activities.

Indirect values: the ecological functions which sustain and protect natural flora and fauna and human systems through services such as maintenance of water quality and flow, flood control, and storm protection, nutrient retention, macro and micro climate stabilisation and the production and consumption activities they support.

Option values: the premium placed on maintaining a pool of species and genetic resources for future possible uses, some of which may not be known now, such as leisure, commercial, industrial, agricultural and pharmaceutical application and water based developments.

Existence values: the intrinsic value of ecosystems and their component parts, regardless of their current or future use possibilities, such as their cultural, aesthetic, heritage and bequest significance.

10.2.8 METHODS OF VALUING ECONOMIC ENVIRONMENTAL VALUES

Various methods can be used in valuing the outputs and existence values of the environmental aspects in economic terms. These include:

Market prices: This is the most straightforward way of quantifying economic values where outputs are traded and market prices are available to indicate the value. In some cases the market prices may need to be converted to economic values to allow for distorting effects of taxes, subsidies and where there is an imperfect market as a determinant of price or value.

Price of alternatives or substitutes: This method involves valuing a product with no market value by comparing it to the value of a close substitute, for example kerosene as an alternative to firewood, and corrugated iron as a substitute to thatching grass.

Collection and production labour: Where products have no market price they may be valued based on the amount of time and labour spent in collecting or preparing the goods at the prevailing wage rate. For example the time spent on collecting products for consumption or firewood for own use. A problem can arise when there is no alternative employment to indicate the prevailing wage rate, so other methods of valuing time have to be applied.

Contingent valuation: A more sophisticated valuation method for valuing environmental benefits that are not marketed or consumed directly by determining consumers willingness-to-pay for a certain amount of the item, as determined through surveys and interviews.

Travel cost approach: Determining the total cost of peoples' time, transport, accommodation and entrance fees for visiting a scenic or environmental attraction as a proxy of the value that they ascribe to the place or feature.

Participatory valuation: A similar technique to contingent valuation but avoids potential distortion caused through using monetary values and instead asks people to value the resource in terms of locally important products or categories of value.

Despite the various method of valuing the benefits some benefits cannot be quantified and are immeasurable, mostly because the necessary scientific, technical or economic data are not available to allow an meaningful and objective valuation. Other aspects of the valuation which relate to human life or cultural significant may involve ethical considerations,


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especially when they are used to argue that specific activities or particular peoples needs are more important than others.

Application of these techniques usually requires specialist knowledge and skills and involves addition costs and time for surveys, participant interviews and analysis of the data. It may be applied when a location as assets or an environment of special significance that requires consideration of the non-monetary benefits to be included in the economic evaluation through the application of these techniques.


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11 OBSERVATIONAND MODELLING

11.1 INTRODUCTION

There is a dire need for comprehensive data on different coastal environmental parameters at the pre-implementation, implementation and post-implementation stages of any coastal protection project. Typically in India such comprehensive data collection is lacking even at the pre-implementation stage of the project, though some data collection/collation takes place just for the purpose of the design of the project. Modelling provides a vehicle by which coastal engineers can illustrate complex interactions, test theories, and project future situations and outcomes. The data is needed in its own right and to supplement the modelling with information for calibration. This lecture concentrates on these two most important topics viz. observation and modelling which are vital for any coastal engineering project.

11.2 NEED FOR OBSERVATION

Planning and designing of coastal structures must be based on sound knowledge and understanding of coastal processes. Towards this, measurements and observations of a wide range of coastal environmental parameters is essential. It is not uncommon that shore protection structures in India are designed even now based on data from the wave atlas published in the eighties which is based on ship based observations. The wave characteristics decide the design of the structure. In the absence of accurate wave data and nearshore profile, the design can go awry. The longshore sediment transport (LST) is another important parameter in design of coastal structures. LSTderived from such erroneous data can often prevent the functioning of the structure and can, as seen in a few cases,do more damage let alone protection of the coast. Another data that is essential is the seasonal beach profile and volume change. When the sea wall is built too far seaward, the beach is lost in front and the wall doesn‘t stop the erosion. While the collection of such precious data from the beach and nearshore was difficult in the past due to operational problems, the availability of sophisticated equipment designed for measurements of littoral environmental parameters isnow available for coastal environmental observations. Moreover while acquisition of such sophisticated equipment may solve the problem with regard to lack of data from the hitherto inaccessible nearshore, the lack of expertise in the processing and interpretation of such data also needs serious thought.

11.3 NEED FOR MODELLING STUDIES

Data collection has to be accompanied by modellingfor understandingthe coastal processes. Though physical modelling has been in vogue until recently, numerical modelling has greatly supplemented the whole gamut of modelling due to its many advantages. The numerical models are able to examine systems to unravel the complexity of the multiple processes that may occur simultaneously. Also, the models can be used in forecast mode to predict future outcomes. The models, after due calibration and validation, can take point data to provide detailed spatial information.

Many projects in India in the past have simply recorded and presented data, without delving into what the data reveals. With models, they have been used at times to simply prove that modelling has been undertaken, rather than using the models to fully test options, scenarios and a careful consideration of the physical system. The model is a powerful tool, but it must


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be used to really understand the existing system first and then used to examine potential benefits or impacts of proposed methods of coastal protection.

11.4 INFORMATION/DATA TO BE COLLECTED

The information/data to be collected can be broadly categorized into two:

1. Locational parameters 2. Coastal environmental parameters

11.4.1 Locational Information

Locational information is a prerequisite for taking up more detailed monitoring of coastal environmental parameters. The following are the important locational information to be collected:

Coastal geomorphology- Themorphological features of the coast has to be understood before venturing into the project. The morphological features give an indication of the processes that form them, especially those that lead to the erosion, transport and deposition of sediments. The morphology may also determine the size of sediment cells, impositions to LST and links between rivers supplying sand and the beach.

Land use and Land cover–Landuse and land cover mapping of the project area is an essential requirement. Land cover data records how much of the coast is covered by forests, wetlands, impervious surfaces,agriculture, and other land and water types. Land use shows how people use the landscape – whether for development, conservation, or mixed uses.

Topography - A detailed map of the surface features of land which includes the mountains, hills, creeks, and other ―bumps and lumps‖is a prerequisite for the project.

Bathymetry - The depths around the region of interest, including offshore,is required for understanding the sea bed topography while alsor providing bathymetric grids for numerical modelling. Bathymetry will often need to be recorded at least twice; at the end of the wet and dry seasons. It also needs to be recorded during the pre- and post-implementation stage of the project.

Soil characteristics -The physical properties of the project site soil such as texture, structure, density,porosity, consistency, resistivity etc. need to be understood.

Performance of existing structures–Information on the performance of existing structures is very useful in the design stage. The performance of the existing structures can tell about thestability of the beach (happy/stable, hungry,etc), littoral environmental characteristics, and so on.

Availability of materials for construction - The availability of materials of the required quality and quantity for construction such as rock, sand, geotextile etc. has to be ensured.

11.4.2 Coastal Environmental Parameters

Collection of coastal environmental data forms the basis for understanding the system so that solutions can be designed which are compatible with the environment and any impacts can be forecast for a decision to be taken with full knowledge of project costs and future reparation that might be required.


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Coastal environmental data is normally needed across a range of categories:

Winds – Many of the processes are responsive to winds, including currents along the coast. Winds measured inland or within tall structures are usually not suitable.

Sea levels – Sea levels vary with tides and a range of other factors like storm surge, coastal-trapped waves and direct wind forcing. Sea level is one of the primary factors determining the design of structures.

Currents – Recording of the currents both offshore and within the surf zone under a variety of weather and wave conditions is required.

Waves – Measurements of waves are essential to predict longshore currents, longshore sediment transport, design material sizes and to know how strong a solution needs to be put in place.

Sediment flux – Direct measurements of sediment fluxes on beaches are rare in India but they need to be made to confirm empirical equations and models.

Beach profile –The beach profiles and the seasonal and annual volume changes computed therefrom are very useful in understanding the sedimentary regime including sand bar movements. Beach profile data provide important clue on the cross-shore and longshore sediment dynamics and the interactions that occur between waves and river/tidal flows around estuarine entrances.

Grain sizes – The sand size plays a critical role in predictions of sediment dynamics and needs to be measured along cross-shore profiles from the top of the beach to at least 10 m depth.

River flows – River flows determine the delivery of sand to the coast and have a strong influence on the formation of deltas at the entrance.

Water parameters – Temperature, salinity, density and chemical contents are often needed to determine the state of the water quality

For a computer modelling study, the measurements are normally made simultaneously.

11.5 MEASUREMENT TECHNIQUES

11.5.1 Bathymetry

Coastal bathymetry is an essential prerequisite for any study. Normally surveys are undertaken offshore from a vessel while a land-based Total Station system is used for the nearshore zone. Jet skis are now commonly rigged with high quality bathymetry instruments in water proof boxes to enable measurements in the surf zone (Figure 11.1). Alternatively, sleds with GPS and reflector can be towed through the surf zone to obtain profiles.

Issues to be confronted relate to the use of high-quality equipment that corrects for wave action through differential GPS, careful measurement of the datum and knowledge of the relationship to Chart Datum. The surveyor must ensure that the ―run –line‖ spacing is small enough to resolve important bathymetric features. When determining the spatial scale, it‘s important to consider the sediment cell size, likely wave orientations and model grid size. Many studies will require 2-10 m horizontal resolution cross-shore and 40-100 m resolution longshore.


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Figure 11.1 Jetski nearshore hydrographic survey system. All of the hydrographic system

components are installed inside a water tight storage compartment.

Data for the seas and coast around India is available from the National Hydrographic Office, Dehradun (http://www.hydrobharat.nic.in/) in contour form. These data provide a high quality baseline, but most studies require more detailed measurements around the region of interest and close to the coast.

On most Indian coasts, the nearshore bathymetry will change between the seasons and so surveys at the end of both the wet and dry seasons are normally needed.

11.5.2 Wind

Currents along the coast, sea level and wave conditions are all responsive to winds. The number of quality wind stations along the coast in India is usually inadequate. For each field deployment, a wind station needs to be established at least 5 m above ground level, without obstructions. The instruments should measure barometric pressure and air temperature. The former is used to eliminate barometric pressure effects from the pressure-based sea level measurements.

11.5.3 Sea Level

Raw sea levels are normally measured at the site by a pressure sensor with in-built computer memory. To discriminate the spring/neap tidal cycle at least 30 days of measurements are needed. In some cases, a convenient sensor may be already located in a nearby port.

The raw records are subjected to a tidal analysis, whereby (1) barometric pressure is removed (2) the tidal constituents are found (3) the residual levels after removing the tides are calculated and (4) the residual is correlated to local winds. Many sea level records will contain variations due to coastal-trapped waves which have not been studied in detail in India.

For modelling the open coast, it‘s often necessary to have two sensors, one at each end of the model domain so that boundary conditions can be established. If an estuary or river is being modelled then levels need to be recorded outside the entrance and deep into the


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estuary. If a river is involved, then records need to be taken during high and low river flows and the effect of the river on levels needs to be determined.

11.5.4 Current

Currents can be recorded in conjunction with waves using a modern wave/current meter like InterOcean S4. These record flows at a particular depth while also recording the sea level variations at high frequency to obtain wave information. The currents are normally taken as the average over 10-15 minutes, while the wave record is often at 2 Hz. Many instruments use burst mode where a burst of data is collected every 30-60 minutes, which enable longer time periods to be stored in memory.

More sophisticated Acoustic Doppler Current Profilers (ADCP) will measure simultaneously in layers through the water column. These are especially useful in stratified flows or to record up/downwelling on a coast.

Deployments should have duration of at least 30 days to record the spring/neap cycle and obtain currents under a variety of wave and wind conditions. Measurements will be needed during both the wet and dry seasons.

11.5.5 Wave

There are different methods for measurement of ocean waves, but the two main types of instruments commonly used are the pressure sensor based wave gauges (eg.Valeport)and waveriderbuoys (eg. Datawell).In India measurements of waves picked up from the 1970‘s.Thanks to the National Data Buoy Programme (NDBP), which was established in 1996 by the then Department of Ocean Development (presently Ministry of Earth Sciences (MoES)), with the objective to operate, maintain and develop moored buoy observational networks in the Indian seas, waves and other Met-Ocean parameters are being regularly monitored. This measurement program is now part of the Ocean Observation System (OOS) of MoES operational at National Institute of Ocean Technology.

Waves can now be very closely predicted by global or regional wave models too. Time series of wave heights, periods and angles are also readily available for purchase from professional suppliers via the internet. Wave hindcasts of more than 30 years provide a high-quality time series for calculating long-term sediment transport fluxes on beaches and for assessing storm intensity and extreme events.

11.5.6 Sediment Flux

Measurement of sand concentrations in the water column and under waves has become technically feasible, although sophisticated equipment is needed which has not been used in India yet.The cost of the equipment is high but at least one research centre in India needs to be given access to this type of equipment, noting the importance of beaches.

Typical sensors are infra-red to record sediment concentrations or acoustic to measure bedforms on the seabed. Others act by trapping a water sample, analysing the sediment for concentration and grain size and then releasing the sample. This may be repeated every 30 minutes. Complex arrays of equipment may be placed on a seabed tripod (Green et al., 1997; Green and Black, 1999)

A less expensive and useful technique is the sediment trap. This is made simply from household PVC pipe with a hole in the top. Sediment falls into the trap over time and the volumes can be converted to water column concentrations, knowing the grain fall velocity. These traps (Figure 11.2) were used in a study to assess the impacts of sand mining at


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Chavara in Kerala (Black et al., 2002).Vijayakumar et al. (2013) used traps to record longshore transport at Pondicherry

.

Figure 11.2 A sediment trap assembly being deployed at the offshore site off Chavara in

Kerala as part of a sediment budgeting study conducted during 1999-2002 (Black et al.

2002)

In some studies, marked tracers can be adopted. These may be actual sand grains marked with radiation, sand painted fluorescent or purpose made sediment beads from fluorescent plastic (Burgess et al., 2007). This technique is particularly useful for directly measuring longshore sediment transport and has been used to track dredge spoil or sand movement around headlands (McComb et al., 2004).

11.5.7 Beach Morphology

The conventional method of measuring the beach morphology is beach profiling. The profiling is normally done with reference to a bench mark in the backshore along a transect normal to the shoreline and extends upto the surf zone. The conventional dumpy level and staff or a total station or a differential GPS can be used for beach profile measurement.Typically beach profiles are preferred at monthly intervals for a minimum period of one year during the pre-implementation stage and at 3 monthly intervals during the post-implementation stage.

A recent method to record the changes that occur on beaches is time-lapse photography or videoimaging through cameras installed at suitable locations facing the beach (Figure 11.3). This allows the beach to be watched for periods when events sculpt the beach topography and sand bars.With careful surveying and software, the images can be ―rectified‖ to provide vertical images that allow the changes to be mapped and digitised in known coordinates.

11.5.8 Sediment Grain Size

The sediment grain sizes on a beach are a key input parameter to models. In India, a sample is normally analysed using sieves of different sizes to find the fraction of each size. For modelling, the fall velocity is needed and so ―fall tubes‖ which measure the time for sand to fall through water are more useful.


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Normally samples will be taken from the low tide, beach face, high tide and upper beach. Further samples need to be taken underwater in mid surf zone, at the breakpoint bar and at 2-3 locations offshore.

Figure 11.3 Time lapse images show the positions of wave breaking on a beach and the sand bars (Ranasinghe et al., 2004).

In many parts of India, the quartz sands are mixed with iron rich black sands (Black et al., 2002). These have different densities and so both components need to be analysed separately. They behave differently under waves and have been observed to be in different ratios on beaches in different seasons (Prakash et al., 2007).

11.5.9 River Flows

In India, the Central Water Commission, being the apex national body for the development of surface water resources of the country, has established a network of hydrological observation stations in all the river basins of the country from where river discharges are being monitored.The rivers have a very strong influence on the coast and are responsible for much of the sand delivery to the beaches. River volume inputs are often an essential dataset for modelling of an estuary or estuary entrance. The river levels also determine flooding, mud inundation, collapse or growth of mud/sand banks and currents around many ports.

11.5.10 Water Parameters

The most common water parameters to record are salinity, temperature, turbidity and conductivity. These measurements will be needed in all estuarine studies to define the intrusion of salt water and mixing processes. They act as a surrogate for current metering, by showing the estuarine dynamics and mixing. Models are often calibrated against salinity as it indicates the advection and mixing of the river inputs with the salt waters from the entrance of the estuary. Turbidity is an important indicator of the concentration of muds being carried to the sea from the river.

11.6 PLANNING AND ESTABLISHING A FIELD PROGRAMME

When planning a field programme, the modelling requirements must be kept in mind. It‘s normally essential also to make measurements simultaneously during an intense measurement period. For example, if currents are measured after sea levels, then it‘s difficult to link these to each other and formulate model boundary conditions or undertake calibration.


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The factors to accommodate are the need to record bathymetry in the surf zone, the difficulty of working in a surf zone and the need to make a broad study, rather than just offshore currents and sea levels. Specialised equipment will be needed and so the Indian institutes need to start planning and accruing these instruments for future use. On an open coast, the boundary conditions are more complex than in an estuary as the model zone is subjected to water level gradients due to tides and factors such as coastal trapped waves (Middleton and Black, 1994).

As an example Figure 11.4shows measurements made to determine the impacts of dredge sand disposal from a port on New Zealand‘s west coast. The marine colonies on the nearby reefs were to be protected from sediment inundation. This project adopted numerous sediment traps and tracers which showed the direction and volume of sediment transport over a period of months. Sand samples were collected regularly and the number of tracer beads in each sample was counted under a fluorescent microscope. At the same time, sea levels and currents were measured at multiple sites.

Figure 11.4 A very large experiment was conducted to determine the movement of dredge sands after disposal. The goal was to gain consents for nearshore sand dumping as the beaches downstream of the port were eroding due to disposal offshore. The data proved to be useful for modelcalibration (McComb et al, 2001).

11.7 MODELS COMMONLY USED

When investigating a site, several different computer models are normally needed to cover the range of processes that occur along the coast. The best models are those which are coupled, i.e. information produced by one model can be readily transferred and utilised by another model. Some models nowadays can treat multiple processes simultaneously, which accounts for non-linear interactions between processes (e.g. tides and surf zone currents) and feed-back systems (e.g. waves building a sand bar or rip current cell which then changes the waves inshore). The type of models most commonly needed fall into the following categories:


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Wave prediction modes: The models use winds to predict the waves at the site. However in many studies, it‘s best to leave these predictions to professionals who will offer/sell their results for local sites.

Tide and current models: These can extend over large areas such as the whole of India. In many studies, boundary conditions are extracted from the large-scale models to drive a local model of tides and currents around the site of interest. Tidal constituents in the world‘s oceans are now available from the internet after many years of satellite observations and modelling.

Longshore transport models: These are the simplest beach models which use the wave time series to calculate the breaking wave conditions, longshore currents and longshore sediment fluxes. While relatively simple, they provide essential data when designing a structure including the intensity of LST and the likely impacts of a structure which may fully or partially block the natural sediment movement along the beach.

Beach dynamics models: These models simultaneously predict the wave-driven circulation (sometimes in 3-dimensions) and the resulting sediment transport.

Beach morphology models: As waves arrive and break around beaches, they drive net circulation. The beach morphology models use the combined effect of waves and currents to predict adjustments to the morphology (beach and sand bars) over periods of years. These models are crucial for understanding the effects of structures and the long-term impacts on the beach. In an estuary or harbour, the model will be more dependent on the tidal circulation and river flows than on the waves. But the complex entrance will need a model that simulates rivers, tides and waves.

Particle advection/diffusion modelling: Particle models use the currents from the hydrodynamic models to predict the pathways of pollutants, muds, dissolved chemicals, floating debris or oil spills. These models show the likely impacts of any discharges on downstream zones, including the expected concentrations.

Primary production modelling: Around discharges like sewerage or pollutants, the primary productivity is altered. Phytoplankton and zooplankton are at the base of the food chain and have a fundamental impact on fish, public health and aesthetics. Too much nutrient can result in harmful algal blooms that may seriously damage the fishery. Understanding primary production near the coast needs to be given more attention in India to ensure a safe and healthy environment for people and marine species.

11.8 MODEL CALIBRATION

Model calibration is the most difficult stage of any project. But before calibration is started, the modeller must analyse all the data to understand the system and thereby carefully choose the models to be used and the boundary conditions. All data must be prepared and presented and any insights about the site coming from the data must be fully evolved and reported before commencing the modelling.

The calibration involves comparing the model with the measurements to ensure that both the model and the modeller‘s assumptions and choices are correct, and matching the environment being simulated.

Figure 11.5 showsan example of model calibration. Calibration is required for every aspect of a project and can prove to be very time consuming. Models cannot be relied on without calibration, and so ―off-the-shelf‖ models without supporting data are not adequate when important decisions need to be taken about coastal solutions. The skill of the modeller is tested during the calibration phase.


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Figure 11.5 Comparison of measurements and a wave prediction model showing wave height, direction and period (Gorman and Black, pers. comm.)

REFERENCES

Bell, R.G.; Gorman, R.; Carter, G.S.; Oldman, J.W. and Black, K.P. (1996) Numerical modelling of a storm discharge from the upgraded Mangere Wastewater Treatment Plant. National Institute of Water and Atmospheric Research Consultancy Report No. WSL60203/4 for Watercare Services Ltd, June, 1996. 17 pp plus figures.

Black, K.P. and Rosenberg, M.A. (1992) Semi-empirical treatment of wave transformation outside and inside the breaker line.Coastal Engineering. 16: 313-345.

Black, K.; Bell, R.; Green, M.; Hicks, M.; Hume, T. Lee; R., Oldman, J. and Sharples, J. (1996) From Point Measurements to Regional Models: Addressing scale and data synthesis in NOSEX, a multi-faceted coastal research programme. Invited paper presented to the Western Pacific Geophysics Meeting of the American Geophysical Union, Brisbane, 1996.

Black, K. (1999) Designing the shape of the Gold Coast Reef: sediment dynamics.Proceedings of the Coasts & Ports ‘99 Conference, 14-16 April 1999, Perth, Australia.Vol 1, pp.58-63.

Black, K.P. and Oldman, J.W. (1999) Wave mechanisms responsible for grain sorting and non-uniform ripple distribution across two moderate-energy, sandy continental shelves. Marine Geology 162, 121-132.


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Black, K.P. (2000). The 3DD Suite of Numerical Physical Process Models. Sanctuary Beach Pte Ltd.

Black, K.P. and Vincent, C.E. (2001) High resolution field measurements and numerical modeling of intra-wave sediment suspension on plane beds under shoaling waves. Coastal Engineering, 42:173-197

Black, K.P., J Mathew, N.P. Kurian, T.N. Prakash and K.V. Thomas, (2002).Heavy mineral budgeting and management at Chavara.Report submitted to Centre for Earth Science Studies, by ASR Limited April, 2002.pp 513.

Black, K.P., Kurian, N.P., Mathew, J. and Baba, M. (2008) Open coast monsoonal beach dynamics, Journal of Coastal Research, 24(1), 1-12.

Black, K.P., Oldman, J., Hume, T. (2005) Dynamics of a 3-dimensional, baroclinic, headland eddy.New Zealand Journal of Marine and Freshwater Research.

Black, K.P., Harrison, S.R., Greer, S.D., Borrero, J.C. and Bosserelle, C.D. (2007). Numerical Modelling of Desalination Plant discharges in Port Philip and Western Port Bays. Technical report prepared for GHD Services Pty Ltd. © ASR Ltd, PO Box 67, Raglan, New Zealand. June, 2007.

Black, K.P. and Mathews, J. (2015) Puducherry Beach Restoration, Task 1: Feasibility Studies for Design Alternatives. Submitted to National Institute of Ocean Technology (NIOT, Chennai, India) by Sanctuary Beach Pte Ltd. 270 pp.

Burgess, S.C., Kingsford M.J. and Black K.P. (2007). Influence of tidal eddies and wind on the distribution of presettlement fishes around One Tree Island, Great Barrier Reef. Marine Ecology Progress Series. 341:233-242

Grant, D.; Black, K.; Osborne, P.; Gorman, R.; Bryan, K.; Villard, P.; Douglass, S.; Radford, J.; Flint, S. and Watkins, N. (1998) Surf Zone Experiments at Cooks Beach and Tairua North, Coromandel, New Zealand. NIWA Internal Report 98/03, WSB802/1: June 1998. 59 pp + appendices

Green, M.O.; Black, K.P. and Amos, C.L. (1997) Control of estuarine sediment dynamics by interactions amongst currents, waves and water depth at several scales. Marine Geology 144(1997): 97-116.

Green, M.O. and Black, K.P. (1999) Suspended-sediment reference concentration under waves: field observations and critical analysis of two predictive models. Coastal Engineering. 38: 115-141.

Healy, T.; Stephens, S.; Black, K.; Gorman, R.; Cole, R. and Beamsley, B. (2002) Port redesign and planned beach renourshment in a huge wave energy sandy-muddy coastal environment, Port Gisborne, New Zealand. Geomorphology 48: 163-177.

Hume, T.M.; Oldman, J.W. and Black, K.P. (2000) Sediment facies and pathways of sand transport about a large deep water headland, Cape Rodney, New Zealand. NZ Journal of Marine and Freshwater Research 34: pp 695-717.

Hume, T.; Payne; G.; Bryan, K., and Black. K. The Cam-Era Network. NIWA Internal Report #59, September 1999, pp18.

Hutt, J.A.; Black, K.P.; Jackson, A. and McGrath, J. (1999) Designing the Shape of the Gold Coast Reef: Field Investigations.Proceedings of the Coasts & Ports ‘99 Conference, 14-16 April 1999, Perth, Australia.Vol 1, pp.299-304.

McComb, P.J., and Black, K.P., (2001). Dynamics of a nearshore dredged-sand mound on a rocky, high-energy coast. Special Issue 34 (ICS 2000), Journal of Coastal Research, pp 550-563.


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McComb, P.J. and Black, K.P. 2004.Detailed observations of littoral transport using artificial sediment tracer in a high-energy, rocky-reef and iron sand environment.Journal of Coastal Research. 20: 212-227.

Middleton, J.F. and Black, K.P. (1994) The low frequency circulation in and around Bass Strait: a numerical study. Continental Shelf Research 14(13/14): 1495-1521.

Prakash, T.N., Black, K.P., Mathew, J., Kurian, N.P., Thomas, K.V., Shahul Hameed, T.S., Vinod, M.V. and Rajith, K. 2007. Nearshore and beach sedimentary dynamics in a placer-dominated coast, south-west India. Journal of Coastal Research, 23(6), 1391-1398.

Ranasinge, R., Symonds, G., Black, K. and Holman, R. 2004. Morphodynamics of intermediate beaches: a video imaging and numerical modelling study. Coastal Engineering. 51(7): 629-655.

Vijayakumar, G., Rajasekaran, C., Sundararajan, T and Govindarajalu, D. (2014).Studies on the dynamic response of coastal sediments due to natural and manmade activities for the Puducherry coast. Indian Journal of Marine Sciences, Vol. 43(7), July 2014.


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12 TRAINING SKILLS FOR MASTER TRAINERS

Aim: To build the skills and abilities of Master Trainers; interactive training with emphasis on

effective ‗training delivery‖ for better learning

Focus: Adult learning principles, tools and techniques; Qualities of a good trainer; Areas of

self-development required; Knowledge and skills required; Appreciate learning preferences

of adults - principles and practices of adult learning; Acquire skills and attitudes

Methods: Concepts, group exercises, and presentations; Training versus learning;

Techniques and tools of training, including group facilitation techniques and use of training

aids; Organizing and managing training programs; Post-training follow up; Training feedback

and effectiveness assessment

The Learning Secrets

A good deal of research has been done and still going on in the field of training. Research indicates that effective learning occurs when all the five senses are engaged. The following should be our constant reminder.

We learn We remember

1% through taste 10% of what we read

1.5% through touch 20% of what we hear

3.5% through smell 30% of what we see

11% through hearing 50% of what we see and hear

83% through sight 80% of what we say

Most effective when we use all the five senses

90% of what we say as we do a thing

Left Brain Right Brain

Controls right side Controls left side

Processes information Thinks in pictures-visualizes

Works in logical sequence Works with wholes, not parts

Controls speech and word order Governs body language

Governs information Draws, paints

Analyses, evaluates and criticizes Centre of intuition, feelings, spontaneity

Memory center for words, numbers and logic

Remembers people, things, experiences

Common sense Creativity

Dominant side in analysts, planners, scientists, mathematicians

Dominant side in painters, designers, artists, sales persons


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The Changing Concept of Training

The Traditional Concept The Changing Concept

Trainees acquire knowledge and acquisition of knowledge leads to action

Motivation and skills of learner lead to action. Skills are acquired through practice.

Participants learn what the teacher teaches. Learning is a simple function of the ability to teach and capability to learn

Learning is a complex function. It is influenced by many factors such as the individual himself, his previous learning, training methods, behavior of the trainer and the climate for learning.

Individual action leads to improvement on the job

Improvement on the job is a complex function. Learning, if unused leads to frustration.

Training is the responsibility of the training experts. It begins and ends with the course.

Training is the responsibility of three partners. The participant‘s organization, the participant and the training experts -all have equal responsibilities. It has three stages viz. pre-training, training and post-training. All the three stages are important for the success of training.

Adult Learning Principles

Adults learn, adults grow and adults change! But remember the following factors while dealing with adult training.

Adults learn what is of interest to them.

Adult learning is self-directed.

Adults use personal experience for their learning.

Main Learning Principles

Adult behavior changes in response to various pressures.

Adults learn best when the environment is safe, accepting, challenging and supportive.

In skill oriented training, full participation of adults must be encouraged.

Feedback is essential and should be made available to adult learners.

Success in satisfying the learning needs provides powerful reinforcement. Therefore, this element should be built into the learning process.

Different adults learn differently. Therefore, training to be effective, the trainer has to be flexible in approach and must use a variety of training styles.


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Training Cycle

Identify Training Needs

Define What after

Training?

Assess Current

Skills

Define Gaps

(Learning Need)

Specify Learning

Path

Produce Learning Modules

Mobilize Training

Resources

Deliver Training

Monitor,

Evaluate and

Improve


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Training Methods

Training is concerned with development of people on-the-job. To achieve this, a wide range of training methods are available. Each method has in-built advantages and disadvantages. Each method has also its utility. The choice of a method is a matter of experience and competence of the trainer. However, it is generally accepted that training methods that invite and stimulate participation by the learners are better than those which limit their involvement.

Training methods can be generalized under three broad groups:

Informative, Participatory andExperiential

You can use a judicious mix of these methods to ensure enhanced learning in coastal adaptation guidelines. The specifics of each of the training methods are described below.

Method Specifics Best suited to cover the following topics

Informative Lecture, Presentation, Film shows, Reading and Writing Assignments, Paper and Pencil Tests

Understanding coastal processes, SMPs and existing guidelines, Preliminary guidelines

Participatory Group Discussion, Brain Storming, Seminar, Syndicate Discussion, On-the-job training, Incidents, Case study, Problem solving exercises, Demonstration, Field visits, Trigger Films

Climate Change, Climate Change Impacts, Sand based solutions, Structural solutions

Experiential Role Plays, Business games, practicing specific skills, Project Assignments, Field visits

Coast tool, Utilizing guidelines, Softness Index Ladder, Exposure visits

Depending on the need any method can be used to make people learn. Some of the important methods are described below.

Lecture

Lecture or Presentation is one of the most commonly used training methods. When you are using lecture method, ask the following four questions.

Who is my audience? Who?

What is the purpose of my talk? Why?

What is the topic? What?

How much time is needed for the topic?

How long?


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Delivering the Lecture

Essentials Actions

Setting the scene Arrive early

Check the arrangement

Covering the material Size up your audience

Start punctually

Refer to notes only when necessary

If you do not know the answer says so. Ask the audience, if they know the answer

Finish on time

Posture Lecture in a standing position

Avoid using lectern, if possible

Move around the class room slowly and steadily

Appearance Appearance in harmony with the occasion

Try to appear formal, if the situation demands

Manner Be poised

Be dignified

Be courteous

Be sincere

Establish eye contact with the audience

Speak to all and not one

Gesture Must be natural

Must be purposeful

Avoid unnecessary movements

Avoid leaning on the table

Voice Speak slowly

Vary pace and volume to avoid monotony

Pause appropriately

Vocabulary Use everyday language

Avoid difficult words and slang

Tell relevant stories

The three parts of the lecture are:

Introduce the topic, Deal with details, Summarize

Advantages and Limitations of Lecture Method

Advantages Limitations

Presentation of facts and opinions in a systematic manner

Only the trainer‘s point of view is presented

Learners can be stimulated to study further

Learners largely remain passive recipients

Large number of learners can attend It can tend to satisfy the needs of the lecturer at the cost of learning


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Group Discussion

Group discussions are conversations between trainees in a structured manner, aimed toward achieving specific learning objectives. In a group discussion, the trainer assumes the role of a facilitator. This method is generally effective when the learners have some work experience.

The mechanics of the method are described below:

Divide the large group into small teams

Each team functions as a sub-group.

The groups are given assignments that they have to complete within a given time frame. You can build-in other restrictions.

Each assignment to the sub-group is given as a ‗brief‘. This has to be carefully prepared beforehand.

One person in the sub-group assumes the role of the leader

Some advantages and limitations of group discussion are:


Secures moderate to high level of involvement

If unstructured, the risk of discussion running lose is high

Participants can assimilate new concepts, techniques and information in a non-threatening manner

Some members may dominate the discussion and may thrust their opinion on the group

Gives an opportunity to communicate openly with other learners

Difference of opinion may be ignored by participants to avoid conflict

Case Study

Case Study is an excellent medium to develop analytical skills. This is one of the best methods of participatory training. This method is increasingly being used in industries and business.

Case is a written description of an actual situation in business. It is an objective description of a ‗real life‘ business situation that are confronted by an organization.

Case is usually organized around one or more problems. A case normally contains enough information to permit meaningful analysis. Cases can range in length from one page to several pages. However, good trainers use cases that can be described in one or two pages.

Case is intended to serve as a class room discussion. It provides a learning situation that depends on the involvement of the learners. The case discussion must be focused yet informal. Some of the questions that need to be asked in case study analysis are as follows.

What is the problem?Who has caused it?

What has caused it? What are the main issues?

Why are the issues important?

Are we looking at causes or at symptoms?

What are the possible courses of action?

What are the possible effects?

Five steps are involved in writing a case study.

Select the type of problem


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Observe and collect relevant data

Be Objective.

Determine the usefulness of the case in learning situations

Use simple language, but make it interesting


It creates several options Tendency to focus on the subject matter rather than the feelings

Helps in developing analytical skills Developing case studies is a difficult task. Time consuming

Helps in gaining new insights and conceptual frameworks

The facts of the case are generally colored by the perception of the writer of the case

Role-play

One of the basic principles in adult learning is that active participation rather than passive reception facilitates learning. Role- play is one of the most effective methods of encouraging participation and involvement.

Role- play is ‗acting out‘. Discussion and analysis to determine what happened and why it happened follow the acting out. In role-play actors have no scripts. At the most they have briefs.

The unique features of role-play are:

It demonstrates the gap between thinking and doing

It permits the practice of carrying out an action in a non-threatening environment

Attitudinal changes can be accomplished by placing persons in specified roles

It trains the learner to be aware of, and sensitive to others feelings

Each one is able to discover his own personal faults

It permits training the control of feelings and emotions

Four types of learning take place through role-play.

Learning by practice of the desired skill

Learning through imitation of desirable behavior

Learning through observation and feedback

Learning through analysis and conceptualization

Role- play can be structured or spontaneous.

The three steps in the role-playing process are:

Step Trainer‟s Role

1. The Warm Up Encourage; remove anxiety

2. The Enactment Permit independence; do not interfere

3. Post-play discussion Focus on experimental behavior and not ‗theatrical effectiveness‘


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Advantages and Limitations of Role Plays


It is a simple and low cost method Risk of role playing becoming an end in itself

It focuses right on the problem Risk of serving only an entertainment value

It provides low risk opportunities to individuals to experiment with new behavior

Over-enthusiastic learners tend to make up facts that are not in the case

It does not require much advance preparation

Tendency of learners to over step their brief

Demonstration

Demonstrations are merely illustrated lectures or presentations. The key to successful demonstrations is a close integration of the spoken and the visual stimulus. Careful planning and ample rehearsal helps a lot in making effective demonstrations. Good demonstrators:

Analyze the process, breaking it into small logical steps

Have all their material in place

Check the operation of all equipment just before they start the demonstration

Position models so that all learners can see all parts at all the time

Explain the goals of demonstration at the beginning

Present the operation, one step at a time

Allow ‗try out‘ of the demonstrated skill

Reinforce correctness in the ‗try-outs‘

Field Visits/Exposure Visits

Planned field visits are good participative learning experiences. The technique helps them to ‗discover‘ for themselves.

A major argument in favor of field visits is that they permit learners to experience sensory impressions which could never occur in class room situations. Few tips to organize structured field visits:

Divide the large group into small sub-groups. Try not to have more than 10 -15 members per group

Provide the background picture

Explain the discipline and safety procedures (if needed) to be followed during the visit

Describe the total picture first

Describe key processes

Explain each process in detail

Provide time for question and answer at the end of the session

You may ask some of the participants to describe what they have observed

Summarize at the end of the visit


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Training Aids

Visual Aids appeals to the sense of sight. Visuals are an excellent way of capturing the learners‘ attention.

While using visual aids, consider their appropriateness to the situation. Poor visibility is the most frequent failure of aids. Basic rules of visibility are:

Use no more than six lines per visual.

Text should be large enough for everyone to see.

Do not block the screen or board while talking.

Organizing a Training Program

The three important stages in a training program are: Pre-training stage, Training stage and

Post-training stage

Stage Must Know Must Do

Pre-

training

Stage

Needs of the group

Objectives of the program

Contents of the program

Methods of training

Mobilize required resources (room, tables, chairs, white board, markers, pencil, notebook, TV, LCD, and Video etc.)

Establish contacts with experts (if required)

Keep a list of participants ready and collect their background details

Training

Stage

Where lunch and refreshments are organized

Timing and venue of the program

Welcome participants

Introduce yourself and other trainers

Provide general information including lunch and tea-breaks

Specify do‘s and don‘ts during the program

Post-

training

Stage

Where participants are located

How to contact them if needed

Who is she/he going to report

Evaluate the program

Write reports

Identify ‗star‘ material and inform her/his boss of your opinion

Managing a Training Program

Most learners are a pleasure to work with, but some are inevitably troublemakers. You need

to deal with them. But first check, whether your attitude in any manner caused that behavior.

To begin with, ensure the following:

Have a well-defined objective and well prepared plan


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Retain high job relevance

Follow acceptable pace

Encourage high interest

Facilitate learning

Provide a low threat environment

Many participants display dysfunctional behavior. Develop skills to handle them. Some

examples of dysfunctional behavior are:

Arriving late

Dominating discussions

Withdrawing from discussions

Arguing with other participants and the trainer

Questioning the trainer‘s competence

Failing to complete assignments

Strategies to manage these behaviors vary from situation to situation.

The thumb rule is not to threaten the participant further. Out of the room one-on-one discussion is the proven method.

Avoid interpreting behavior.

Avoid arguments.

Be descriptive. Give specific examples.

Be polite but firm.

Take control of the situation. Do not let the group drift.

Describe how others are affected by her/his behavior.

If several participants display frequent dysfunctional behavior, it may be a good idea to raise your concern with the group.

Six Stages of a Training Session

1. Forming

Introductions and getting to know activities

2. Storming

The negotiation begins between the learner and what has to be learned. You are the

mediator; your tactics are lecture, discussion, demonstration, project work, role-play,

reading assignments etc.

3. Restoring

The provision of rest and refreshments to take care of learner‘s learning curves.

4. Norming

Learners come to terms with their learning tasks, understand what is required of them,

and stimulateeach other‘s learning. You provide reinforcement by way of feedback on

progress; encourage questions and provide answers, using different learning methods.

5. Learning

Learners practice what they have learned, demonstrate they can do or prove what the

program was about by written tests, demonstration, quiz etc.


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6. (De) Parting

Wind down or debrief: where the learners go from here, what they can do with their new

knowledge and skill.

Training Tips

1. First Impression

First impressions count. Do not forget a friendly smile. Tell a relevant and appropriate

story.

2. Respect your Audience

Acknowledge the worth of your audience. Respect their knowledge and eagerness to

learn. Never ridicule them. Do not hurt their sentiment by out of place jokes.

3. Maintain Eye Contact

Look at individuals occasionally as you talk to them, but do not be afraid to look away.

4. Use Gestures

Use your voice and body to convey your message. But do not overdo it. Try not to wave

your arms distractingly.

5. Posture

When you are not gesturing stand still: do not fidget, sway or click with your pen or

awkward movements.

6. Keep Smiling

You don‘t have to have a grin on your face all the time. Nevertheless, be ready to smile

when the occasion warrants it.

7. Structure your talk

Tell what you are going to tell. Tell. And then tell what you have told.

8. Style of Delivery

Change the pace, speed and quality of delivery. Vary the pitch of your voice; deepen for

emphasis, lighten for humor.

9. Speech

Use conversational language.

10. Keep it Simple

Keep it Simple and Short. Use examples, illustrations and comparisons.

11. Be Positive

Emphasize the positive. Don‘t be a gloom and doom merchant even if you are talking

about the worst scenario.


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12. Anticipate Questions

Anticipate questions as much as you can. Be prepared and provide practical answers.

13. Be Polite, but firm

Deal immediately with comments from the floor that you do not agree with. Provide

reasons and steer the discussion back to the main point.

14. Use Humor

Use humor for effect but don‘t be a clown. Make it relevant.

15. Show Enthusiasm and be Alert

Finally, communicate your enthusiasm. If you are genuinely interested in what are you

saying, you won‘t be able to hide it. Watch signs of boredom such as yawning and cross

talking. Deal with such issues promptly. Demonstrate that you are in control.


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25-27 JULY 2016

LECTURE NOTE BY

M.D.KUDALE


13 OVERVIEW OF COASTAL ENGINEERING

13.1 INTRODUCTION

There is long history of interaction of mankind with ocean. Perhaps primitive man halted at seashore

and thought how to sail through the waves. Since then the endeavour to understand ocean and

coastal process is enormous. The term "Coastal Engineering" as employed in the present context is

first introduced in October of 1950 at the first conference held at long beach, California, U.S.A. Most

of the problems taken up under the heading "Coastal Engineering" were previously considered as

one important part of Civil Engineering especially port and harbour engineering. In connection with

port and harbour construction, wave hindcasting, wave force estimation, disturbances within basins

and sediment movement have been basic problems in breakwater planning, design and

construction. Technically the coast is that strip of ground bordering sea, which alternately exposed

or covered by tides and waves (Fig.1). Coast is continuously changing, at best they are in dynamic

equilibrium sediment moving offshore and then back onshore, along the shore in one direction and

then perhaps in the other direction.

The subject of Coastal Engineering can be divided in three groups:

i) Understanding coastal processes

ii) Coastal structures and their impacts on coastal processes

iii) Tools available for solving the problem.

13.2 COASTAL PROCESSES

In coastal environment waves, tides, currents and winds are the important parameters which need

to be considered for any development. It is very much essential to understand the physics of these

processes.


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13.2.1 Waves

In many situations, wave is the single most important parameter, which influences design

considerations. Waves are generated in the offshore region by the interfacial shear extended by

wind blowing over the sea surface. As such, they are also called a wind waves. The parameters

which govern the wave generation process are Fetch of water surface which is subjected to wind

(F), Wind speed (V), Duration of wind (t).

Waves in the generation area are of variable heights and frequencies and propagate in all directions.

These are known as waves. However, when waves leave the generation area and travel towards the

coast they get segregated according to frequency due to dispersion of waves, which are known as

swell waves. A typical wave form as measured at deep sea is shown in Fig.2.

The wind waves are short waves (Fig.2b) with Period (T) varying between 1 and 30 sec,

height varying between 0.5 and 5m and wave length (L) is of the order of few hundred

meters. However, during the severe cyclones the wave heights may be upto 10 m or higher.

As restoring force for this kind of wave is gravity these are also known as gravity waves.

When depth is more than L/2 the wave does not feel the bottom. But in shallower region wave

undergoes changes due to various process like:

Refraction

Diffraction

Shoaling

Breaking

Decay of energy due to friction

In deep water the wave length (Lo) is given by

Lo = gT2 / 2

Wave speed Co is given by

Co = Lo / T

In shallow water using small amplitude wave theory it is derived that :

L

dgTL

2tanh

2

2

The waves are classified as deep water or shallow water waves according to relative depth (d/L) as

follows:

½ < d/L : deep water waves

1/20 < d/L< ½ : intermediate waves

d/L < 1/20 : shallow water waves


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The wind energy in the offshore region is transported to the coast in the form of waves which

constantly agitate the coastal region. The waves cause dynamic impact on coastal structures, which

they must withstand. A typical wave force diagram is shown in (fig.2c). The waves influence

navigation of ship as well as ship motion at berth affecting the operation at berth. At coast, the

waves result in movement of sand along the shore causing erosion or accretion of shoreline. The

waves stir up the sediments at the bed and bring them into suspension, which are transported by

currents, which may lead to siltation in harbours and approaches. Therefore, understanding

mechanism of waves is important to coastal engineers.

13.2.2 Tides

In most of the seas and estuaries one can observe the periodic rise and fall of the water level. If one

visits to seashore at a particular time and observe the water line on the beach and again he returns

to the beach after few hours he will find that the water line has receded or advanced. This is due to

tidal fluctuation. This is called astronomical tide as it is produced by the attraction force of sun,

moon, earth and other celestial bodies. A typical tide observed at site is shown in Fig.3a.

13.2.3 Harmonic analysis of tides

On account of the regularity inherent in astronomical processes, certain harmonics may be easily

identified in oceanic tides. In general terms, the temporal variation of water level may be

described by an equation of the form

)cos(0 ii

n

ji

i ta

where,

= water level (normally hourly observations over 29 days)

o = mean water level above local datum (average of 69611 values)

i = frequency of the i'th component (obtained from astronomical theory)

ai = amplitude of the i'th component (determined from each constituent)

i = phase of i'th component (determined for each constituent)

n = number of harmonics used to generate tide

t = time

With a 29 day record of hourly observations, 9 constituents (M2, S2, N2, K2, K1, O1, P1, M1, MSo) may

be determined. The notation is M = moon, S = sun, MS = compound tide 1 = diurnal, 2 = semi diurnal,

4 = quarter diurnal, etc. A 360 day record of hourly observations will give 30 constituents. The


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relative importance of diurnal and semi-diurnal components may be evaluated at any locality by the

ratio F, where

22

1

SM

OKF

If F < 1.0, there will be a strong semi-diurnal influence. If F>> 1.0 the tides will be diurnal.

Approximate values of mean low water springs (ML WS) and lowest possible low water (LPL W) are

given by

ML WS = o -(M2 + S2)

LPLW = o -1.2 (M2 + S2+ K2)

The period of the vertical movement is about 12 hours 25 minutes known as the tidal period and

denoted as T (Fig.3b). The highest level is called as high water (HW) and lowest level is called as

low water (LW). The difference between HW and L W is called the tidal range. If we measure the

vertical movement of the water level for about 24 hrs, we would observe that the second HW

and L W would differ from the first HW and L W. This difference in consecutive HW and L W is

known as diurnal inequality. If we observe the tide for longer period (say about month) then we

see that the tidal range varies with time. There are periods with large tidal ranges which are

called spring tides, the periods with small tidal range known as neap tide. The time between two

periods of spring tide is about 15 days. The above observations are in relation to a fixed location.

The tide however, is a long wave of wave length of several hundreds of kilometers. Typical tidal

wave observed at a time along Hugli estuary is shown in Fig.3c.

From the figure it may be seen that at Hugli wave length is about 300 km. It is also observed that

water surface slope is generated due to tide. This surface slope generates tidal current. During rising

stage of tide velocity is in one direction and during falling stage the velocity reverses. In sea, tide

induced current is less usually is of the order of tens cm/sec. But in estuary the tide induced velocity

is quite high usually 1 m/sec. 2 to 3 m/sec is also observed at certain places.

Flood and ebb flow do not follow the same path moreover they are not of same magnitude. This

dissimilarity causes net movement of sediment and pollutant.


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13.2.4 Wind

Wind is always present in ocean environment. Besides generating wave wind also produces current

and water level set up and set down. At times of storm water level set up created .by wind velocity

as well as pressure difference submerge large areas of land. In ocean environment any Structure

projected above water level are subjected to wind load. It is observed that water does not move in

the direction of wind. Once water particle starts moving due to wind, friction force and Coriolis force

start working on that and particles starts moving in a direction making an angle with wind direction.

Position of coastline with respect to wind direction governs current field (Fig.4a).

Ekman has also derived vertical profile of velocity generated due to wind (Fig.4b). It is observed

that with depth direction as well as magnitude of velocity changes. Wind is also responsible for

creating sand dunes at the shore.

13.2.5 Beach Process and Sediment Transport

The sediment transport phenomenon is very complex in coastal area. In the near shore zone the

decreasing water depths affect the wave motion, eventually leading to the wave breaking and

running up on to the beach. Four zones can be distinguished (Fig.5):

i) Deep water: Here the water depth is large compared with the wave length of the waves, the wave

crests are straight, the velocity of propagation C and angle of incidence, relative to the shore are

constant.

ii) Refraction zone: The waves feel the bottom, the wave length and velocity vary as they progress

through the period remains constant. The wave crests are progressively bend to parallel the shore

line and the waves steepen and eventually break.

iii) Surf zone: This is the zone between the breaker point and the shore. The breaker line is not a

fixed line since the position of breaking varies with the wave height, higher waves breaking farther

down the shore: Within the surf zone measurements have shown that there is well defined long

shore current.

iv) Swash zone: This is limited by the highest point on the beach that the breaking waves run up to,

and the lowest point to which the water recedes between waves.

13.2.6 Littoral Transport


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Although waves tend to become parallel with coast as a result of refraction, they usually break

at a slight angle to the shore with the result that a "littoral current" is effective in moving a mass

of water slowly along the coast in the surf zone. One of the important effects of littoral currents

is movement of sand along a coast as "littoral drift". The littoral current, combined with the

agitating action of breaking waves, is the primary factor in causing such sand movement. Studies

indicate that the greatest percentage of sand transported along a coast occurs shoreward of

breaker zone.

Besides alongshore movement, wave also causes onshore offshore movement of water mass

and sediment. The distribution of velocity over depth as function of wave height and wave

period as well as depth averaged velocity is shown in fig.6. The velocity though small causes

huge mass transport per unit width because of large depth. As this mass of water meets the

coast there will be return flow. This phenomena causes onshore offshore movement of

sediment. Atypical onshore-offshore movement of sediment during storm event is shown in

fig.7. During storm beach erosion takes place. During normal wave action beach is built up.

13.3 COASTAL ENGINEERING PROBLEMS

Coastal engineering problems may be classified into four general categories: shoreline stabilization,

backshore protection (from waves and surge), inlet stabilization, and harbour protection (Table-1). A

coastal problem may fall into more than one category. Once classified, there are various solutions

available to the coastal engineer. Some of these are structural; however, other techniques may be

employed, such as zoning and land use management.

Table-1 indicates structures or protective works that fit into the four general problem

classifications and factors that must be considered in analysing the problem. Hydraulic

considerations include wind, waves, currents, tides, storm surge or wind set up and the basic

bathymetry of the area. Sedimentation considerations include the littoral material and processes

(i.e., direction of movement; rate of transport, net and gross; and sediment classification and

characteristics) and changes in shore alignment. Navigation considerations include the design

craft or vessel data, traffic lanes, channel depth, width, length and alignment. Control structure

considerations include selection of the protective works evaluating type, use, effectiveness,

economics and environmental impact. In selecting the shape, size, and location of shore-

protection works, the objective should be not only to design and engineering work which will

accomplish the desired results most economically, but also to consider effects on adjacent areas.

Economic evaluation includes the maintenance costs and interest on capital cost. If any plan

considered would result in enlarging the problem by extending its effects to a larger coastal

stretch or prevent such enlargement, the economic effect of each such consequence should be

evaluated. A convenient yardstick for comparing various plans on an economic basis is the total

cost per year per metre of shore protected.

13.3.1 Method of study

Before taking up any construction in coastal area a thorough hydraulic study is required in

respect to its functional utility, stability, and its impact on surrounding environment.


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The studies are usually taken up by site inspection, field investigation, physical modeling,

mathematical modeling. Recently, remote sensing is also used to understand global phenomena

prevailing in the area.

13.3.2 Site inspection

Site inspection by qualified and experienced engineers is very much essential before actual study. In

fact experienced engineers can understand the problem, possible solution, data requirement for

study during site inspection.

13.3.3 Field Investigation

Bathymetric chart, wave climate, tidal levels, velocity field, bed material, size distribution, beach

slope, suspended load concentration, salinity, bore well data all these data depending upon the

nature of problem form integral part of any study to be taken up data are collected through

intensive field investigations.

13.3.4 Physical Modelling

Scale model are long being used to study coastal engineering problem. Different types of models are

used in dealing with coastal engineering problems:

i) Wave model: Wave models are undistorted model usually used to determine wave tranquillity or

simulation of littoral current in coastal area.

ii) Tidal model: Tidal models are distorted model used for simulation of tidal phenomena like tidal

level, tidal current.

iii) Wave cum tidal model: For simulation of inlet phenomena where both wave and tide are

important wave cum tidal model are used. These models are usually distorted.

iv) Wave flume: Wave flumes are used to test breakwater section or any other maritime structure

under regular and irregular waves.

v) Hot water circulation model: As a number of power plants are situated along the coast of India,

hot water circulation model are used for these studies. These are usually wave cum tide model

having facility of injecting hot water and measurement system of temperature rise.

The scale models used for studying coastal engineering problems are Froudian model. Equality

of Froud number both in proto and model is used for deriving model laws –


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i.e.

mpgd

V

gd

V

dp

dm

Vp

VmVr

Similarly other model laws can be derived.

13.3.5 Mathematical modeling

Since last two decades mathematical modeling has become a very efficient tool for studying

coastal engineering problem. These models are essentially based on conservation of mass and

momentum equation. Similar to scale model, there are tidal model as well as wave model. These

models can be three dimensional (3D) or two dimensional (2D) depending upon governing

equation. At present for coastal engineering problems mostly two dimensional models are used.

In mathematical modeling, the region of interest are schematised by regular square grids in finite

difference method or by irregular triangular grids in finite element method. In natural closed

boundary usually no flow condition for tidal flows and reflection coefficient for wave model are

provided as boundary condition. At open boundary observed tide or flow (velocity) are used as

boundary condition for tidal model. For wave model observed wave (height and period) and wave

angle are used as boundary condition.

In tidal model Navier stokes equations are solved to get tidal level, velocity (magnitude and

direction) at all interior wet grid points. Instantaneous velocity field are depicted by vector

diagram. The water level fluctuation and continuously changing velocity field can be

demonstrated through animation.

In wave model two equations are solved (i) conservation of wave energy (ii) irrotationality of

wave number. As output wave models produce wave height and wave direction. The results are

presented both as vector field indicating magnitude of wave height and wave direction at all grid

points, Also wave isolines are presented to indicate wave crests and troughs.

Besides tidal and wave model sediment transport model, pollution transport model, ship

navigation model, ship motion models are also used.

Various models used at present are shown in Table-2.


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13.4 CONCLUDING REMARK

Coastal engineering is a multidisciplinary subject which needs a very good team work for

studying a project.


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25-27 JULY 2016

LECTURE NOTE BY

A.V.MAHALINGAIAH


14 COASTAL EROSION AND PROTECTION MEASURES

14.1 INTRODUCTION

Coastline is an interface between the ocean and the land. It is dynamic morphological entity,

which responds to the external forces exerted by waves, tides and near shore currents and

resultant sediment movement. Coastal erosion is recession of the shoreline and loss of land

area due to action of waves, currents and wind. Human interference also contributes to the

adverse effects along the coastline, including the erosion. The physical regime of the Indian

coastline is characterized by different types of coastal features like promontories, Sand spits,

Barrier beaches, Embayments, Estuaries and offshore Islands etc. The morphological

changes near shore region are entirely due to waves, tides and other environmental

parameters, which cause changes in the coastline in the form of recession or advancement.

In the most part of Indian coast, the erosion observed is seasonal in nature, ie. beach gets

eroded during monsoon and regains its original profile during fair weather season. The

magnitude and nature of erosion changes from place to place. However, at some places,

erosion is of permanent nature and there is a need to protect on priority. The causes of

coastal erosion are broadly classified as natural and human causes.

In order to mitigate the coastal erosion, the coastal protections are provided and are broadly

classified as soft and hard solutions, and also combination of both. The coastal resources

are over exploited with the increase in coastal population, which have resulted in threatening

of not only our coastal resources but also the entire eco-system of the coastal belts. The

protection does not only stop the erosion of the coast but also saves the cultivable land

being inundated and protects important structures and valuable properties along the coast.

The methodology/solutions need to be evolved with thorough understanding of the various

coastal processes, with due consideration to the environmental aspects as well as should be

easily constructible in minimum period of time. The solutions evolved for protecting the

coastline will vary considerably depending on the extent of erosion and environmental

conditions. The site specific measures to combat erosion are required to be evolved based

on evaluation of coastal environment conditions prevailing at the site, availability of material

and equipment and resourcefulness of execution team. As such, the site specific protection

measures are evolved based on coastal environment of the different coastal regime. Some

coastal protection measures are described in detail, which depict the importance of site

specific solutions for coastal protection.


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14.2 CAUSES OF COASTAL EROSION

The causes of Coastal erosion are broadly classified as natural and human causes.

Natural Causes

i) Increased rate of net littoral drift due to change in wave conditions

ii) Erosion during extreme wave and storm surge conditions

iii) Loss of sand into canyons

iv) Sea level rise

v) Deflation – sand movement due to wind

vi) Subsidence – lowering of the surface in certain region

vii) Variation in supply of sand from rivers due to droughts

Human Causes

i) Interruption to littoral drift by constructing structures such as breakwaters, navigational channels.

ii) Dredging and disposal of sand while maintaining the navigational depths in channels and harbours

iii) Removal of sand from the beach

iv) Obstruction to natural supply of sand from rivers

14.3 MEATHODS OF COASTAL PROTECTION

The coastal protections are broadly classified as soft and hard solutions, and also combination of both.

14.3.1 Soft solutions

Plantation of Vegetation: Planting or replacement of appropriate species of vegetation to assist in the stabilization of dunes, bluffs or banks. Useful to reduce sediment loss due to wind, Eco-friendly solution.

Artificial Beach nourishment: Introduction of material along a shoreline to

supplement the natural littoral drift. Sand is added to existing beach Natural Eco-


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friendly way to combat coastal erosion Preserves flora fauna, recreational opportunities, controls flooding.

Sand bypassing: Hydraulic/mechanical movement of sand from an area of accretion to a downdrift area of erosion, across a barrier to natural sand transport.

Flood proofing: Flood proofing measures is the elevation of homes

Zoning: Implementation & enforcement of planning & zoning by-laws to control development in flood & erosion hazard zones

Retreat: In some cases, it may be less expensive to relocate endangered structures than to invest in large scale shore protection.

Do nothing: No action, or do nothing approach is commonly used by engineers to help evaluate different courses of action.


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Armour

Secondary layer

Toe

Existing beach Profile

Sea side Lee side

High Water Level

Filter

Core

Crest

14.3.2 Hard solutions

14.3.2.1 Protective structures

a) Seawalls

i) Relatively massive structures, parallel to the shoreline

ii) Rubblemound or vertical monolithic structures

iii) Prone to damage due to scouring at toe

Types of Seawall

A typical rubblemound seawall

The toe protection is supplemental armouring of the bed surface in front of structure, which

prevents waves from scouring and undercutting it. The computations for the unit weight of

armour using stones by Hudson‘s formula as shown below:

Where, W =Weight of armour unit (kg), KD= Stability coefficient

wr = Unit weights of armour block (kg/cum),

H = Wave height at the proposed structure (m)

Sr = Specific gravity of the armour units

Ө = Angle of armour slope measured with the horizontal,

cot)1(

.3

3

SrK

HwW

D

br


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b) Revetments

i) Parallel to the shoreline and sloped in such a way as to match the natural slope of the shoreline profile

ii) Similar to seawalls, exposed to lower level of attach of waves

iii) Rubblemound structures and does not feature back-slope armour

Types of Revetments

c) Other Protective structures

i) Bulkheads primarily retain the land

ii) Dikes primarily prevent the flooding

14.3.2.2 Structures to Trap Sediment Movement

a) Groynes

i) Normally constructed in a series, perpendicular to the shoreline

ii) Traps sediments by interrupting or reducing long-shore drift

iii) May cause down-drift erosion

Forms of Groynes

b) Offshore

Breakwaters

/ Detached

Seawalls

i) Normally constructed in a series, Parallel to the shoreline

ii) Breaks waves before they reach shoreline

iii) Traps sediments by providing calm area on leeside

iv) May cause down-drift erosion


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Offshore Breakwater

The detached breakwater is constructed parallel to shore, which leads to formation

of Salient/Tombolo on lee side.

LB = Length of detached breakwater

x = Detached breakwater distance from the shoreline

x80 = Surf-zone width (Approx. 80% of littoral transport take place landward to this

line)

LB * = LB / x X*= x/X80

LB * < 0.6 to 0.7 - Formation of Bell shaped Salient

LB * > 0.9 to 1.0 - Formation of Tombolo

c) Artificial Reefs / Perched Beaches / Sills

a) Submerged, detached structures, constructed parallel to the shoreline, traps sand brought in by wave action, or brought in by man.

b) Differ from submerged offshore breakwaters in having wider crown c) Useful when used in front of seawalls or revetments

Artificial Reef

14.3.2.3 Combination of Artificial Beach

Nourishment & Structures The sand brought in for Artificial Nourishment can be held up by constructing structures like Groynes, Offshore /Detached reefs, or artificial Reefs. Effective and most widely used


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method. Cost of Artificial Nourishment Project mainly depends on the availability of suitable sand. This method avoids frequent refilling of the eroding beach. 14.3.2.4 Use of Geo-synthetic Tubes/Bags /mats/filter etc.

a) Geo-synthetic tubes/ Bags filled with sand can be used for beach protection

b) Groins, detached seawalls, anti-sea erosion bunds can be formed using sand-filled Geo-synthetic Tubes / Bags.

c) These materials are available under various trade names.

14.3.3 Limitations of Conventional Methods

The present practice followed to mitigate the coastal erosion in India is construction of seawall or

groyne, depending upon whether sediment movement is onshore-offshore or there is littoral

transport. These coastal structures are flexible and are normally of conventional type, which

requires heavy stones/concrete blocks in the armour. In case of rubblemound seawalls

constructed conventionally, the placing of stones of required gradation in the armour per unit

surface area of armour is rather difficult, tedious and also requires sophisticated cranes for placing

of heavy stones/armour. As such, major part of the cost of construction of such marine structures

is entirely due to placing of heavy stones or concrete blocks in the armour / cover layer.

Equipments such as cranes with long booms are required to place these heavy stones / blocks in

the armour layer and also in the toe. The present methods of construction of seawall/groyne by

conventional method have following limitations:

Non availability of suitable construction material from nearby quarry

Non availability of construction equipment like crane

No space for movement of construction equipment at site

Time span in which the work is required to be completed

Non availability of sufficient beach width

14.4 SITE SPECIFIC SOLUTIONS OF COASTAL PROTECTION MEASURES

A coastal protection measure in a given situation depends on the following three primary conditions;

a) problems (coastal erosion, beach degradation or flooding)


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b) morphological conditions (type of coastal profile and coastline)

c) land use (Infrastructure/habitation, recreation, agriculture etc.)

The conventional method of coastal protection by providing massive seawalls has some limitations viz. non availability of suitable construction material & machines, no space for movement of construction equipment at site and non availability of sufficient beach width. In order to overcome these, the various site specific coastal protection measures are examined and evolved. The site specific solutions are in the form of seawall with higher toe-berm, detached seawalls, offshore reefs, seawall with concrete stepped crest slab, concrete piles for bank protection, artificial beach nourishment, offshore reefs with artificial beach nourishment, groyne field, sand bypassing, revetment with heavy stones pitching, bank protection with stones pitching etc. Design of few site specific solutions for the coastal protections are discussed below: 14.4.1 Seawall with higher Toe-Berm

If the beach profile is with composite slope, the hydraulic stability of structure should be

confirmed for each individual part of the structure. The stability of the toe is essential; else

failure of the toe will generally lead to failure of the whole structure. The utility of the toe can

be enhanced by providing flatter slope of toe face, or by providing horizontal berm on the

seawall face at a level close to the design water level. However, this toe is exposed to the

direct wave attack, since the waves are breaking on the toe berm or toe slope.

Seawall/revetments without toe will not serve the purpose as the wave force will cause

damage to the seawall/revetments. In view of these constraints at the coastal erosion site

along the National highway near Maravanthe in Karnataka, the erosion problem was solved

using a seawall with higher toe-berm . The toe berm is kept at higher level than the design

Highest High Water Level (HHWL). A flatter toe slope is provided to protect the armour and

crest vis a vis the highway by absorbing the brunt of the breaking wave energy on toe berm

itself, reducing the uprush and prevent overtopping or splashing of the water on to the

highway embankment. The toe takes the brunt of the breaking waves and subsequently

reduces the uprush. The concept of seawall with differential toe helps in reducing the

overtopping of the waves on the crest vis a vis provides better protection to the coastal

highways.

Severe Erosion at Maravanthe (left); coast after construction of seawall (right)


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Cross-section of seawall with higher toe-berm

14.4.2 Toe Protection to the Vertical Wall

A historical Somnath temple is located on the west coast of India in Saurashtra, Gujarat.

Recently, a part of the retaining wall on the seaside of the temple suffered damage due to

action of sea waves. A rubblemound slope at the toe of the vertical wall, which prevents

scouring and undermining of the vertical wall.

Retaining wall at Somnath temple (left); Wave flume tests for toe protection (right)

The vertical walls constructed along the coast with rocky bed slope at several places in

Mumbai (ie. Priyadarshini park, Worli, Dadar Chaityboomi, etc.) suffered damages due to

wave action. A toe protection in the form of seawall with tetrapods in the armour is

suggested at these sites. This solution with tetrapods in the armour is useful from aesthetics

point of view in the city like Mumbai.


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Toe protection in the form of seawall to vertical wall

Seawalls with tetrapods in the armour

14.4.3 Seawalls with Stone-Filled Gabions

The coastline at Tithal near Valsad was under the threat of severe erosion for many years.

Swami Narayan temple near the coast was in danger as the boundary wall of the temple is

located very close to the coast. It was proposed to construct seawall with stone filled flexible

gabions to provide immediate protection to the temple. The coastal protection work was

completed in very short time using the local labours. The construction of protection works

has been maintained regularly. The section is stable and beautiful beach has been formed in

front of the structures, due to better dissipation of wave energy on the stone filled gabions.

Seawall with stone filled Gabions at Tithal


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14.4.4 Bank Protection in the Creek

Pankhol Juwa is an Island located well inside the creek on north side of Malvan,

Maharashtra. The loose soil of the bank has tendency to slide and wash away due to the

tidal currents and flow during monsoon. The bank profiles are very steep and space required

for construction is substantially less. Since the site is situated well inside the creek, locally

generated waves, tide and currents are considered for design. In view of the site condition, it

was decided to design protection measures in the form of PCC driven piles with conventional

bank protection technique. PCC driven piles of 0.3m diameter at 1.5 m spacing are

suggested and top of the piles is fixed at el. +1.0m. The gabions (zinc coated wire) filled with

20 to 40 kg trap stones are placed in between the piles and bank slope. The piles would

hold the gabions on steeper slope.

PCC piles for bank protection


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14.4.5 Seawall with stepped crest slab

Seawall with stepped crest slab

A beautification plan on the beach with coastal protection against waves has been proposed

for tourism places at Shrivardhan, Dahanu and Kelwa beaches, in Maharashtra. It was

decided to incorporate beautification components consistent with the proposed coastal

protection work. A rubble mound seawall consisting of 0.5 to 1.0 t stones with 1:2.5 slope in

the armour layer was proposed to sustain the wave attack. L-shaped PCC parapet wall was

suggested at top with a layer of PCC blocks resting on soling layer. The armour stones are

to be placed in pitching fashion from asthetic point of view and ramps at suitable interval are

proposed for access to the beach.

14.4.6 Artificial Beach Nourishment and Submerged Reefs with Geo-tubes

The sand filled geo-tubes with submerged reefs, groynes are proven to be economical

alternative for coastal protection. The Geo-tubes are made up with woven polypropylene

fabrics with fibrillated yarns. Requirement of the beach width is the main criterion for

deciding the alignment or the depth contour of the offshore reefs. The submerged reef

combined with sand nourishment helps rapidly stabilization of the beach. As such, the

offshore reefs could be of dual purpose viz. allowing overtopping of the hydraulic loading for

the formation of the salient/tambolos at high water level and holds nourished/deposited sand

on the beach against downrush. Generally, the emergent offshore reefs for the purpose of

holding sand are constructed at the nearshore region without gap and special attention has

to be provided for the turbulence created by the breaking of waves. Ultimately, crest

elevation and the alignment location of the offshore breakwater play a key role in deciding

the design cross -sectional details. Use of the geo-tube as an offshore breakwater for

holding the nourished sand is the new trend adopted in India instead of the conventional

rubblemound offshore structure. Effort should be taken to extend life span of the offshore


215

geo-tubes upto the permanent beach stabilization. They can be appropriately covered with

sand. The tubes are susceptible to damage due to the rocky bed or can be easily tampered.

Artificial beach nourishment and submerged reef with Geo-tubes

Submerged reefs with geo-tubes have been provided at INS-Amla, Mumbai. A continuous

row of the 3.0 m dia and 1.0 m dia geo-tubes are provided at a distance of about 50 m away

from the existing compound wall at the bed level of +1.0 m. The tidal range in this area is

about 5.2 m and with this top portion of goe-tube is kept at Mean Sea level of +2.6 m. It was

expected to act as intermediate submerged reef and would help in arrested the nourished

sand on the beach. The nourishment of beach carried out with well graded coarse sand.

Over a couple of seasons a wide beautiful beach has been created and part of these

submerged reefs are buried with sand. Similarly, submerged reef with geo-tubes are

provided at Dahanu and sand deposit take place in the next season.

14.4.7 Sustainable Coastal Protection Measures at Ullal, Mangalore

An integrated development plan prepared by the ADB Consultants for sustainable coastal protection includes i) Construction of two offshore reefs, ii) Construction of four nearshore-


216

berms with geo-textile containers to trap the sediments, iii) Beach nourishment of the Ullal beach, iv) Re-habilitation of breakwaters to allow more sand movement towards south.

Figure: Sustainable Coastal Protection Measures at Ullal, Mangalore

14.4.8 Shoreline Management Scheme

Major morphological impact was felt after development of Ennore port, as this coastal region

is having high longshore littoral drift. It is observed from the studies that, the annual

northward and southward transports are of the order of 0.60 million cum & 0.10 million cum

with net and gross transports being 0.50 million cum and 0.70 million cum. respectively. The

northward transport is more dominant and hence the net transport is towards north. Also it is

observed that the major northward transport occurs in SW monsoon period. In order to

protect the eroding northern coastline, accommodate the dredged sand to meet the

requirement of additional area, eco-friendly multipurpose solution is planned for shoreline

management with combination of sand bypassing and beach nourishment to combat erosion

on downdrift side. Sand trap is suggested at the entrance in the protection zone of the


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Layout and cross-sections of Geo-tubes for beach nourishment

breakwater from which sand would be dredged throughout the year. The dredged sand

would be bypassed on the northern shoreline by deploying a pipeline from a dredger berth

extending along the northern coast.

Groyne fields are also employed in combination with shoreline protection in order to develop

a beach. A layout of groyne field consisting of 10 groynes of 40 m length each has been

suggested on the north side of northern breakwater. Sand-filled geo-tubes of 3m diameter

are to be placed perpendicular to the shoreline to form a groynes field. This eco-friendly

solution would protect the coastline as well as meet the requirements of the port for disposal

of dredged material.

Shoreline management scheme at Ennore Port

14.4.9 Other Specific Coastal Protection Measures in India The site specific solutions have been evolved at number of locations for coastal protection along the Indian coast. Rubblemound seawalls with stones/tetrapod in the armour have been adopted at Paradip, Mumbai, Maravanthe, Mangalore, Alleppy and seawalls with flexible Gabions at Tithal, Varsoli, Ankaleshwar. Groins and detached seawalls with stones/geo-


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tubes have been used at Udwada, Dahanu and Shankarpur. Artificial beach nourishment is successfully carried out through sand bypassing systems at Visakhapatnam and Paradip Ports. Low cost protection schemes are found successful at Lakshadweep & Minicoy Islands. CWPRS Involvement Central Water & Power Research Station (CWPRS), Pune has major involvement in costal protection works in India. Wave flume facilities at CWPRS are used for Hydraulic model studies for design of Coastal Protection Structures. CWPRS is the Nodal agency for Coastal Data Bank and conducts training programs for various State Government Agencies. REFERENCES

Bruun.P (1972), ‗The history and philosophy of coastal protection‘ proceedings 13th

International Conference on Coastal Engineering, (ICCE) Vancouver, Canada, 1972

U.S. Army Corps of Engineers, coastal Engineering, (1984); Shore Protection Manual,

(SPM1984), U.S. Government Printing Office, Washington D.C., USA

M.D. Kudale, A.V. Sitarama Sarma “Guidelines for Design & Construction of Seawalls”, CWPRS

Technical Memorandum. May, 2010

CWPRS Technical Report No. 4316 (2006). Desk & Wave Flume Studies for Strengthening of Existing Seawall & Evolving Shore Protection Works NH-17, at Maravanthe, Karnataka

CWPRS Technical Report No.4658 (September 2009), Desk studies for shoreline management for the proposed phase-II development at Ennore port, Tamilnadu

A.V.Mahalingaiah, M.D.Kudale, ―Eco-friendly solution of coastal protection by shoreline management for port development in littoral zone‖ proceedings of National Conference on Hydraulics and Water resource (Hydro-2011) Dec 2011.

A.V. Mahalingaiah, M.D.Kudale;(2014),"Hydraulic model studies for safe and optimal design

of Rubblemound breakwaters"- International Journal of Earth Sciences and

Engineering, ISSN 0974-5904, Vol. 07, No. 02, pp.400-404, April 2014

A.V. Mahalingaiah, B.R. Tayade, N.V. Gokhale, M.D. Kudale; (2015) ―Design of Submerged Offshore Reefs for the Coastal Protection Measures‖ - Science Direct, Aquatic Procedia, ELSEVIER Journal Publication, ISSN: 2214-241X, Volume 4 (2015), pp.198-205, March 2015

http://www.sciencedirect.com/science/article/pii/S2214241X15000280

http://www.sciencedirect.com/science/article/pii/S2214241X15000280

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