Water Management

Chapter No. 4Water Management (6 to 8 Marks Theory)

Content of the Topic:Part A:-

• Sources of water• Introduction to Dams• Types of Dams• Introduction to canals

Part B:-• Methods of Irrigation• Rain water Harvesting

Prepared by Mr. KORE P. N.

Questions from University Paper

• Name and explain different methods of irrigation. (4 Mks)• Name different methods of irrigation. (2 Mks)• Explain rain water harvesting with neat sketch. (4 Mks)• Enlist types of Dam. Explain any one with sketch.(4 Mks)• Draw the cross section of concrete dam and show various

level? (4 Mks)• Selection of Dam site. • Write short note on: (4 Mks) each

• Methods of Irrigation• Sources of water• Types of Dams• Drip Irrigation


Part-IWhat is Water Management?

Water management is an activity of planning, developing, distributing and managing the optimum use of limited water resources under defined water policies and regulations.

Why water management?• India- Agricultural land• Main Source of water- Rain• Rainfall- Uncertain - Unpredictable• Types of rainfall- rain, hail, snow and dew (shown in Following Fig.)• Use of water for remaining months of year


RAIN (main source)

HAIL

SNOWMain source of water

DEW

• Rain water is the basic source to fulfill the day to day requirements.

• But not more than 2% of the rain water is utilized.Prepared by Mr. KORE P. N.

Other Sources of Water


What is Hydrological Cycle ?Hydrological Cycle

Hydrological Cycle (Simplified View)

Also called water cycle


Types of Sources of water:

Surface Water Underground water

• Ponds and Lakes • Springs

• Streams and Rivers • Infiltration Galleries

• Storage Reservoirs • Infiltration wells

• Oceans and Seas • Wells and Tube wells

Figures as shown below …….


POND

LAKE


Tube Well

WellInfiltration well

River


DAMS

Content:

• Introduction

• Selection of Dam site

• Types of Dams


Canal

Content:

• Introduction

• Types of Canals

DAMS (are massive structure constructed across the river)


Storage reservoir

• It is an artificial lake formed on the upstream side of the river by

constructing a dam (or barrier) across it.

• So the constructed barrier will form a reservoir which can be utilized

as a source of public water supply through canals and sub-canals.

• Therefore we have to study • Dams (source)

• Canals (supply)

• Method of irrigation or systems of irrigation (procedure)


1. Dam is a massive structure or a solid barrier constructed at a suitable location across a river valley to store flowing water behind it.

2. Dams are constructed with concrete, stones and/or with earth (i.e. soil) also.

3. Dam has rectangular, triangular and /or trapezoidal cross sections.4. The dam which withstands the water pressure by its own weight is

known as ‘Gravity Dam’.

Storage reservoir



Dams: Different cross sections

Rectangular Dam

Triangular Dam

Trapezoidal Dam

Gravity Dams

These dams are heavy and massive wall-like

structures of concrete in which the whole weight

acts vertically downwards

ReservoirForce

As the entire load is transmitted on the small area of foundation, such dams are constructed where rocks are competent and stable.


Selection of Dam Site:

1. Availability of suitable foundation

2. The river valley should be narrow at dam site (it becomes economical).

3. The river valley should be wide at upstream side (to store maximum water).

4. The river bed level at the dam site should be at higher than the river basin.

5. Site for spillway should be availability near to the dam site.

6. Nearness of the locality.

7. The reservoir basin should be leak proof.

8. Minimum land and property should be submerged.

9. The dam site should be accessible to the cities.

10. The project should meet the increased demand in future.


Stored water is utilized for following purpose:

• Drought and flood control

• Generation of hydropower

• Irrigation

• Water for domestic consumption

• For navigational facilities

• Other additional utilization is to develop fisheries.






Structure of Dam

Heel

Gallery

Toe

Spillway(inside dam)

Crest

NWL(Normalwater level)

MWL (Max. Water Level)

Free Board

Sluice way

Upstream U/S Down stream D/S


Max. level

Heel: contact with the ground on the upstream side

Toe: contact on the downstream side

Abutment: Sides of the valley on which the structure of the dam rest

Galleries: small rooms like structure left within the dam for checking operations.

Diversion tunnel: Tunnels are constructed for diverting water before the construction of dam. This helps in keeping the river bed dry.

Spillways: It is the arrangement near the top to release the excess water of the reservoir to downstream side

Sluice way: An opening in the dam near the ground level, which is used to clear the silt accumulation in the reservoir side.


Structure of Dam



Spillway

SpillwaySpillway

TYPES OF DAMS

• Earth dam

• Rock-fill dam

• Solid- Masonry Gravity dam

• Hollow- Masonry Gravity dam

• Steel dam

• Timber dam

• Arch damPrepared by Mr. KORE P. N.

Earth Dams: They are trapezoidal in shape.Earth dams are constructed

where the foundation or the underlying material or rocks are weak to support the masonry dam or where the suitable competent rocks are at greater depth.

Earthen dams are relatively smaller in height and broad at the base.

They are mainly built with clay, sand and gravel, hence they are also known as Earth fill dam or Rock fill dam.


Cross Section

Earth dam


Earth dam


Loose rocks and boulders are piled in the river bed

to construct such damsThe dams are made water-tight by applying a slab of R.C.C. on U/S surface of dam.

Rock-fill Dams


Timber Dam


These type of dams are concrete or masonry dams which are curved or convex upstream in plan

This shape helps to transmit the major part of the water load to the abutments

Arch dams are built across narrow, deep river gorges, but now in recent years they have been considered even for little wider valleys.

Arch Dam


Arch Dam





Canal

A Canal is a trench or path through which the water fromreservoir flows towards the areas to be irrigated.

Definition:

Types of Canal

Reservoir Main Canal

Branch Canal

Distributory

Major Distributory

Minor Distributoryor Field Channels


Storage Reservoir

Branch Canal

Major Distributory

Minor Distributory

Farm Farm

Irrigation System

River Flow

Main Canal

CanalCanal

Farm

Branch Canal


IrrigationIrrigation engineering is defined as that branch of engineering which deals with the artificial supply of water to the soil in accordance with ‘crop requirement’ throughout the ‘crop period’ for full fledged growth of the crop.

Importance of Irrigation

1. India has wide cultivable land and 70 % population depend on it.

2. The rain-fall is insufficient during the year.3. So it is essential to supply correct quantity of water to the

plants at correct time.4. This requires collection of water during excess rainfall and

distribute it to the agricultural lands according to requirement.


Irrigation

Surface Irrigation Sub-surface Irrigation

Flow irrigation

Lift Irrigation (well)

Natural Sub-surface

Irrigation

ArtificialSub-surface

Irrigation

PerennialIrrigation

FloodIrrigation

Direct Irrigation (River)

StorageIrrigation

(Tank)

ValleyIrrigation

DeltaIrrigation

Open wellIrrigation

Tube wellIrrigation

Methods of Irrigation:

Flow Irrigation or Gravity Flow Irrigation


Flow Irrigation

Flow Irrigation


Flood Irrigation or Inundation Irrigation


Flood Irrigation (Inundation Irrigation)


Flood Irrigation


Left Main Canal

Right Main Canal

RiverReservoirDam

Storage Irrigation (Tank Irrigation)


River

Left Main canal

Right Main canal Diversion Weir (a low height wall which is constructed across the river) Direct Irrigation

Drains

Drains


Furrow Irrigation


Drip Irrigation System in Farm


Spray IrrigationUsed to irrigate large uniform areas


What is Rainwater harvesting?

The term rainwater harvesting is being frequently used these days, however, the concept of water harvesting is not new for India. Water harvesting techniques had been evolved and developed centuries ago.

First Aim: Conserve Water


• Ground water resource gets naturally recharged through percolation.

• But due to rapid development of urbanization, exposed surface for soil has been reduced drastically with resultant reduction in percolation of rainwater, thereby depleting ground water resource.

• Rainwater harvesting is the process in which their is filtration of rainwater in to the underground formation by some artificial methods.

What is the aim behind Rainwater harvesting?

How to harvest rainwater ? Broadly there are two ways of harvesting

rainwater

Surface runoff

harvesting Roof top rainwater harvesting


Rain water Harvesting

Concept


In urban area rainwater flows away as surface runoff. This runoff could be caught and used for recharging aquifers by adopting appropriate methods.


Purpose of Rainwater harvesting

• To arrest ground water decline and augment ground water table.

• To beneficiate water quality in aquifers. • To conserve surface water runoff during monsoon. • To reduce soil erosion. • To inculcate a culture of water conservation.



Thank you …

Water Management

Engineering