Presentation_Value of Mangroves in Coastal Protection
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8/4/2019 Presentation_Value of Mangroves in Coastal Protection
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Presented By:
Akil HossainB. Sc In Environmental Science
DisciplineKhulna University
Value of Mangroves In Coastal Protection
In Bangladesh
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Mangroves are a diverse group of unrelated trees, palms, shrubs, vines
and ferns that share a common ability to live in waterlogged saline soils
subjected to regular flooding.
They are highly specialized plants that have developed unusual
adaptations to the unique environmental conditions in which they are
found.
There are around 80 species of mangroves found throughout the world.
Most commonly they occur within tropical and subtropical sheltered
coastal areas subjected to tidal influences.
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Mangroves can be divided into two distinct groups:
Exclusive mangroves
The largest group, comprising around 60 species (Saenger et al., 1983)
These mangroves are confined to intertidal areas and have not been found
to exist within any other type of vegetation community
Non-exclusive mangroves
Comprising around 20 plant species
These plants are not restricted to the typical mangrove environment and
are often found within drier, more terrestrial areas
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Mangroves are found along estuaries and marine shorelines
High tide and low tide are the common phenomena
Mangrove roots provide an oyster habitat and slow water
flow, thereby enhancing sediment deposition in this areas
Due to the high salinity and frequent tidal inundation
mangrove tree species show distinct zonation
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Adaptations to low oxygen
Limiting salt intake
Limiting water loss
Nutrient uptake
Increasing survival of offspring
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Problem Identification
The coast of Bangladesh is known as a zone of vulnerabilities as well as
opportunities. It is prone to natural disasters like cyclone, storm surge andflood. The combination of natural and man-made hazards such as erosion,
high arsenic content in ground water, water logging, earthquake, water
and soil salinity, various forms of pollution, risks from climate change,
etc, have adversely affected lives and livelihoods in the coastal zone and
slowed down the pace of social and economic developments in this
region.
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Nature of Coastal Disasters in Bangladesh
The entire coastal zone is prone to violent storm and tropical cyclones
during pre monsoon and post monsoon season. The cyclone accompanied
with torrential rain and devastating tidal surge causes havoc to lives and
property in the cyclone path, and the environment in the affected area.
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Causes of Coastal Vulnerabilities
The poverty monitoring survey of Bangladesh Bureau of Statistics (BBS) summarized
crises in following categories. Are-
a. Human factor i.e. sudden death of the main income earner, large medicalexpensesdue to illness, crop loss, social conflict etc.
b. Natural disaster like cyclone, tidal surge,water logging, erosion, salinity intrusion,
etc
c. Governance i.e. deterioration of law and order situation (dacoity, money extortion,abduction, snatching, death threat, case expenditure, occupying of govt. khas land,
natural resource base e.g. destruction of mangroves, overexploitation of natural
resources etc (PDOICZMP, 2003).
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The above figure reveals that the coastal human ecosystem is greatly
threatened by human factors and ill governance that creates imbalances in
productivity and in the distribution of goods and services.
Source: PDOICZMP, 2003
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Cyclone and Coastal Vulnerabilities
The entire coastal zone is prone to violent storm and tropical cyclones during
pre monsoon and post monsoon season. Sometimes cyclone associated with
tidal waves caused great loss of lives and property.
Source: ICZM-2003
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COASTAL PROTECTION
Mangroves as Bio-shield: Evidence from around the world
Research and experience have shown that forest ecosystems reducing the
physical exposure of natural hazards and providing people with the livelihood
resources to withstand and recover from crises
Mangrove Forests Saved Lives In Tsunami Disaster
Mangroves can absorb 70-90 percent of the energy of a normal
wave, even though reliable figures for tsunamis are not available.
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Foreshore Protection
Acting as a natural buffer to water erosion from both the land and the sea.
By creating a physical barrier
Slowing water movement from the land
Trapping sediments
Reduce erosion along estuaries and creeks
Dampen storm surge and tropical periodic cyclones
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Intertidal/Muddy Coast
This type of coast is characterized by fine-grained sedimentary deposits,
predominantly silt and clay that come from rivers; it can be classified as asoft coast. It has a broad gentle seaward slope, known as an intertidal mud
flat where mangrove forest, saltmarshes, shrubs and other trees are found.
Most erosion is generated by river damming that reduces sediment supply,
diminishes vegetation cover (usually mangroves and saltmarshes) and
exposes vegetation roots by lowering the mud flat that leads to their final
collapse.
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Scientific findings on the protective functions of coastal forests and trees
Scientific investigations on how coastal vegetation provides a measure of
shoreline protection have been show that mangrove forest and othercoastal vegetation of certain density can reduce wave height considerably
and protect the coast from erosion, as well as effectively prevent coastal
sand dune movement during strong winds. Healthy coastal forests such as
mangroves and salt marshes can serve as a coastal defense system where
they grow in equilibrium with erosion and accretion processes generated
by waves, winds and other natural actions.
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Maintaining ecological balance of the nature
By photosynthesis, supply nutrients and oxygen to animals and plants in the ecosystem.
link up the ecosystems of the land and sea.
Every hectare of mangroves can feed 12 tonnes of living things including insects, reptiles,amphibians, birds, invertebrates and various aquatic microorganisms.
Foraging and living places for wildlife
Reducing water pollution
keeping the fishery yields in coastal and offshore areas.
Acts as a sight-seeing route of eco-tours, and brings financial incentives to the community.
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Oil spills from theinternational ships, mechanize trawlers, andwater
vessels passing through the Sundarbans.
Rising sea level threatens to inundate low-lying areas and offshore
islands in the country's coastal belt
Almost all the forest area is now under shrimpfarms.
Salt Pans have been set up within the forestareas
because of lesser tide inundation andthus vegetation is getting destroyed
Encroachment and illicit removal of
timber andfuel wood is increasing
Marginallands, with about half of the
forestlands beingcultivated or occupied.
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Possible management scenarios
Public awareness and education about the mangrove forests may help protect them. It is
necessary to involve local communities in managing and protecting their mangroves.
Designated conservation areas may also save some of the forests.
Proposals/ actions need to be taken to avert future natural disasters
Action has to be taken for reforestation, restoration and development of the mangroves.
Public education campaign is to be conducted to make local communities, the tourism
industry and other sectors aware of the importance of mangroves.
Periodic mapping of Sunderbans mangrove forests has to be carried out using
the Remote Sensing and GIS technology to monitor the changes in the ecosystem.
Social forestry can be useful for eco-restoration of mangrove vegetation through creation
of employment opportunities
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Any Question?
Contact:S.M. Samkeyat Shohan
Phone Call: +8801672048125Email: shohan_es08@yahoo.com
Akil HossainPhone Call: +8801738383863Email: akil_08es@yahoo.com
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