364
11.3 Results
Major factors and their sub-factors of mangrove degradations are categorized after
the field investigations and monitoring shoreline changes over a time and space in
the region of Sundarban coasts. Southern shores of Namkhana-Henry’s Island,
Jambu Island, Lothian Island, Mousumi Island and Sagar Island are eroded after the
impacts of previous cyclones. Younger bars are emerging in the shallow sea parallel
to the shoreline that playing an important role for concentrating the tidal energy
creating or directing the long shore currents into the shorelines of concavities and
convexities at present. The low-lying shores with a high tidal range (>3.9 m) are
liable to erosion under such conditions in which mangroves are lost and sediment
stability is affected.
The current extent of mangroves has been dramatically reduced from the original
extent nearly every country (Burke et al. 2001). The leading human activities that
contribute to mangrove loss are 52% of aquaculture (38% shrimp plus 14% fish
production), 26% by forest use, and 11% by fresh water diversion (Valiela et al.
2001). Restoration has been successfully attempted in some places, but this has not
kept pace with wholesale destruction in most areas. A large number of poor people
are directly or indirectly dependent on the forest uses in the Sundarban. One estimate shows that about 1 lakh people in West Bengal and 2 lakhs people in Bangladesh
enter into the forest areas of the Sundarban in the month of April for the collection
of non-timber forest products and other types of forest materials. Original extents of
mangrove forests are converted into fish ponds in the northern fringes and southwestern fringes of Sundarban in West Bengal (Fig. 11.3).
11.3.1 Studies of Mangrove Degradation in the Coastal
Wetlands of Southwest Sundarban
Mangrove degradation checklists are prepared for a number of islands of southwestern Sundarban (Henry’s Island, Fredrick Island, Bakkhali, Patibania Island, Jambu
Island and Mousuni Island) for the present study. However, only three islands are
selected for application of such method for assessing the nature of mangrove degradation at present.
11.3.2 Islands of Namkhana Abad with Extent of Mangroves
The extent of mangroves is still evident in the buffer areas of reserve forest of the
Sundarban. Forest interface society is located in the fringe areas of such extent of
mangrove forest of the southwestern Sundarban.
A.K. Paul et al.
11.3 Results
Major factors and their sub-factors of mangrove degradations are categorized after
the field investigations and monitoring shoreline changes over a time and space in
the region of Sundarban coasts. Southern shores of Namkhana-Henry’s Island,
Jambu Island, Lothian Island, Mousumi Island and Sagar Island are eroded after the
impacts of previous cyclones. Younger bars are emerging in the shallow sea parallel
to the shoreline that playing an important role for concentrating the tidal energy
creating or directing the long shore currents into the shorelines of concavities and
convexities at present. The low-lying shores with a high tidal range (>3.9 m) are
liable to erosion under such conditions in which mangroves are lost and sediment
stability is affected.
The current extent of mangroves has been dramatically reduced from the original
extent nearly every country (Burke et al. 2001). The leading human activities that
contribute to mangrove loss are 52% of aquaculture (38% shrimp plus 14% fish
production), 26% by forest use, and 11% by fresh water diversion (Valiela et al.
2001). Restoration has been successfully attempted in some places, but this has not
kept pace with wholesale destruction in most areas. A large number of poor people
are directly or indirectly dependent on the forest uses in the Sundarban. One estimate shows that about 1 lakh people in West Bengal and 2 lakhs people in Bangladesh
enter into the forest areas of the Sundarban in the month of April for the collection
of non-timber forest products and other types of forest materials. Original extents of
mangrove forests are converted into fish ponds in the northern fringes and southwestern fringes of Sundarban in West Bengal (Fig. 11.3).
11.3.1 Studies of Mangrove Degradation in the Coastal
Wetlands of Southwest Sundarban
Mangrove degradation checklists are prepared for a number of islands of southwestern Sundarban (Henry’s Island, Fredrick Island, Bakkhali, Patibania Island, Jambu
Island and Mousuni Island) for the present study. However, only three islands are
selected for application of such method for assessing the nature of mangrove degradation at present.
11.3.2 Islands of Namkhana Abad with Extent of Mangroves
The extent of mangroves is still evident in the buffer areas of reserve forest of the
Sundarban. Forest interface society is located in the fringe areas of such extent of
mangrove forest of the southwestern Sundarban.
A.K. Paul et al.