391
flushing rate of deltaic streams with high evaporation rate, and increased storminess
of the sea control the fate of mangrove wetlands by spread of hyper-salinity. Seaward
zones of Island, estuarine Islands of younger origin and inner parts of mangrove
dominated Islands are mostly affected by degradations.
All the factors and sub-factors are identified with the observations of spatiotemporal characters of coastal wetlands in and around the South western Sundarban.
Identification of potential threats of the coastal wetland is possible by the preparation of mangrove degradation checklists. The MDC can provide thus a perspective
for management opportunities and challenges to restore the coastal wetlands dominated by mangroves in the Sundarban. The Principal Component Analysis (PCA)
for identified multiple factors reveals that hypersalinity, storm effects, land erosion,
sediment deposition and fishery development are mainly responsible for mangrove
degradations in the coastal wetlands of Southwest Sundarban.
The coastal wetlands of Sundarban dominated by mangroves are potentially
threatened by degradations in a multiple way of risk factors. This is a great challenge to the forest department and coastal zone management authorities of India and
Bangladesh to achieve the desired conservation objectives for the sea face of
Sundarban wetlands in an even more sustainable manner against the upcoming
threats with predicted sea level rise in the region. The assessment of geomorphological perspectives of mangrove ecology in regional settings and preparation of
mangrove degradation checklists (MDC) can provide ideal tools for identification of
potential threats to the coastal wetlands of Sundarban.
The physical effects of sea level rise in the form of storminess of the sea, land
erosion at the shore fronts and along the estuarine banks, over wash sand depositional lobes behind the beaches and bars, high evaporation rate and hypersalinity,
conversion of wetlands for fish farming plots by local people to adjust with salt
water flooding, and spread of eutrophication in the surface depressions of swampy
tract are drivers of mangrove wetland degradations in the Sundarban. The zoning of
wetland management should not be restricted only in the emerged hyper saline
patches or in areas of tidal drainage loss by creating artificial drainage lines for supply of moistures and fresh silts through salt water inflows but, other areas of emerged
bars, river flats, buffer areas of reserve forests and emerging areas of salt water
flooding incidences also should be considered for restoration of wetlands by mangrove afforestation at present.
Fig. 11.17 (continued) decomposed algae mat into the lower part; (c) the pit cutting of a hyper
saline patch showing the location of animal burrows into the lower part of vertical profile underlain
by salt encrusted top layer. The mangrove swamp was produced in the past when the animal burrows were developed into that layer; (d) the die back of mangrove vegetations and conversion of
some vegetation into dwarfed condition due to increased salinity of top soil; (e) the mangrove trees
uprooted from the wetland areas affected by slumping mud banks of the Island fringed tidal channel; (f) the loss of mangrove vegetation due to the erosion and retreating mud banks of compact
clayey platform dominated by Hental trees (Phoneix peludosa); (g) the chunk of forest patch is
submerged due to undermining and collapsing process of Island platform fringed with the active
tidal channel; and (h) sediments removed from the swampy surface dominated by mangrove trees
(Rhizophora sp.) during storm events may produce damage to the vegetations in the near future
11 Mangrove Degradation in the Sundarbans
flushing rate of deltaic streams with high evaporation rate, and increased storminess
of the sea control the fate of mangrove wetlands by spread of hyper-salinity. Seaward
zones of Island, estuarine Islands of younger origin and inner parts of mangrove
dominated Islands are mostly affected by degradations.
All the factors and sub-factors are identified with the observations of spatiotemporal characters of coastal wetlands in and around the South western Sundarban.
Identification of potential threats of the coastal wetland is possible by the preparation of mangrove degradation checklists. The MDC can provide thus a perspective
for management opportunities and challenges to restore the coastal wetlands dominated by mangroves in the Sundarban. The Principal Component Analysis (PCA)
for identified multiple factors reveals that hypersalinity, storm effects, land erosion,
sediment deposition and fishery development are mainly responsible for mangrove
degradations in the coastal wetlands of Southwest Sundarban.
The coastal wetlands of Sundarban dominated by mangroves are potentially
threatened by degradations in a multiple way of risk factors. This is a great challenge to the forest department and coastal zone management authorities of India and
Bangladesh to achieve the desired conservation objectives for the sea face of
Sundarban wetlands in an even more sustainable manner against the upcoming
threats with predicted sea level rise in the region. The assessment of geomorphological perspectives of mangrove ecology in regional settings and preparation of
mangrove degradation checklists (MDC) can provide ideal tools for identification of
potential threats to the coastal wetlands of Sundarban.
The physical effects of sea level rise in the form of storminess of the sea, land
erosion at the shore fronts and along the estuarine banks, over wash sand depositional lobes behind the beaches and bars, high evaporation rate and hypersalinity,
conversion of wetlands for fish farming plots by local people to adjust with salt
water flooding, and spread of eutrophication in the surface depressions of swampy
tract are drivers of mangrove wetland degradations in the Sundarban. The zoning of
wetland management should not be restricted only in the emerged hyper saline
patches or in areas of tidal drainage loss by creating artificial drainage lines for supply of moistures and fresh silts through salt water inflows but, other areas of emerged
bars, river flats, buffer areas of reserve forests and emerging areas of salt water
flooding incidences also should be considered for restoration of wetlands by mangrove afforestation at present.
Fig. 11.17 (continued) decomposed algae mat into the lower part; (c) the pit cutting of a hyper
saline patch showing the location of animal burrows into the lower part of vertical profile underlain
by salt encrusted top layer. The mangrove swamp was produced in the past when the animal burrows were developed into that layer; (d) the die back of mangrove vegetations and conversion of
some vegetation into dwarfed condition due to increased salinity of top soil; (e) the mangrove trees
uprooted from the wetland areas affected by slumping mud banks of the Island fringed tidal channel; (f) the loss of mangrove vegetation due to the erosion and retreating mud banks of compact
clayey platform dominated by Hental trees (Phoneix peludosa); (g) the chunk of forest patch is
submerged due to undermining and collapsing process of Island platform fringed with the active
tidal channel; and (h) sediments removed from the swampy surface dominated by mangrove trees
(Rhizophora sp.) during storm events may produce damage to the vegetations in the near future
11 Mangrove Degradation in the Sundarbans