370
sediments from seaward face to inner parts of the delta plains. The landward
advancement of sediment lobes submerges the forests, wetland surface and tidal
creeks at a steady rate with increased frequency of storm events in the deltaic
coast at present.
5. Storm effects: The tropical cyclone breaks in November 2007, April 2009,
November 1988, October 1989 and November 1991 devastated mangroves on
the coast of the Bay of Bengal in Bangladesh and West Bengal (India). The
stumps of mangrove trees on the shore front mud banks are the remains of the
devastation. Sediments have been stripped from the forest floor in which the root
system of mangrove trees is exposed in unearthing condition in the foreground.
The top breakage of mangroves in the inner forest records winds thrown activities of cyclone landfall on the deltaic coast fringed by Bay of Bengal.
Such storm effects have been monitored along the Sundarban shores after the
events in many places to estimate the wetland losses. Prolonged inundation by
salt water flooding and fire ball activities during storm events also devastated
mangroves in the Sundarban coast in the past.
6. Land erosion: Low-lying deltas flat is the place of geographical habitat to support the vegetated tidal flat along the seaward parts of Sundarban. The rate of
land erosion between 1989 and 2015 shows a great loss of mangrove forests as
well as coastal wetlands in the Sundarban (Figs. 11.5 and 11.11). Various mechanisms of land erosion resulted from hydrodynamic stress have produced significant damages to the mangrove wetlands along the coastal belt. All the sea front
islands with mangrove forests have been reduced in size and shape due to erosion in the previous decades. Erosion and flooding related activities will be
increased in steady state if the current sea level rise takes place as per predictable
rates in the Sundarban Delta (Table 11.4).
It is established by the present study made by Raha et al. (2014) that other
than sea level rise, many factors like sediment deposition, lack of fresh water
flow in the deltaic part and natural subsidence of the deltaic platform are also
playing a major role in the loss of mangrove wetlands in the Sundarban.
7. Mangrove regeneration problems: Large number of mangrove seeds is regularly drifted into the unfavorable sandy substrate after the events of storms, tidal
waves; southwest monsoon brace and HAT (Highest Astronomical Tides) phase
currents along the shores of the Bay of Bengal. Litters and huge amount of viviparous mangrove seeds are usually deposited along the high tidal limit of the
sandy shores of south west Sundarban during monsoon months. Large number
cattle population with other livestock generally feed on mangrove seeds along
the sandy shores (Fig. 11.7).
The wave beaten compact mud banks on the foregrounds of high tide shoreline do not provide the anchorage facilities for mangrove seeds in the dynamic
current condition. Tidal dispersal of mangrove seeds cannot reach the supra tidal
flat affected by drainage loss, particularly in the inner parts of islands away from
channels and shorelines. Other activities like crab potting, clay mining, and
unscientific netting across channels and intertidal flats also disturb the process of
seed anchorage. Mangrove trees in the sapling stage are also affected by insect
A.K. Paul et al.
sediments from seaward face to inner parts of the delta plains. The landward
advancement of sediment lobes submerges the forests, wetland surface and tidal
creeks at a steady rate with increased frequency of storm events in the deltaic
coast at present.
5. Storm effects: The tropical cyclone breaks in November 2007, April 2009,
November 1988, October 1989 and November 1991 devastated mangroves on
the coast of the Bay of Bengal in Bangladesh and West Bengal (India). The
stumps of mangrove trees on the shore front mud banks are the remains of the
devastation. Sediments have been stripped from the forest floor in which the root
system of mangrove trees is exposed in unearthing condition in the foreground.
The top breakage of mangroves in the inner forest records winds thrown activities of cyclone landfall on the deltaic coast fringed by Bay of Bengal.
Such storm effects have been monitored along the Sundarban shores after the
events in many places to estimate the wetland losses. Prolonged inundation by
salt water flooding and fire ball activities during storm events also devastated
mangroves in the Sundarban coast in the past.
6. Land erosion: Low-lying deltas flat is the place of geographical habitat to support the vegetated tidal flat along the seaward parts of Sundarban. The rate of
land erosion between 1989 and 2015 shows a great loss of mangrove forests as
well as coastal wetlands in the Sundarban (Figs. 11.5 and 11.11). Various mechanisms of land erosion resulted from hydrodynamic stress have produced significant damages to the mangrove wetlands along the coastal belt. All the sea front
islands with mangrove forests have been reduced in size and shape due to erosion in the previous decades. Erosion and flooding related activities will be
increased in steady state if the current sea level rise takes place as per predictable
rates in the Sundarban Delta (Table 11.4).
It is established by the present study made by Raha et al. (2014) that other
than sea level rise, many factors like sediment deposition, lack of fresh water
flow in the deltaic part and natural subsidence of the deltaic platform are also
playing a major role in the loss of mangrove wetlands in the Sundarban.
7. Mangrove regeneration problems: Large number of mangrove seeds is regularly drifted into the unfavorable sandy substrate after the events of storms, tidal
waves; southwest monsoon brace and HAT (Highest Astronomical Tides) phase
currents along the shores of the Bay of Bengal. Litters and huge amount of viviparous mangrove seeds are usually deposited along the high tidal limit of the
sandy shores of south west Sundarban during monsoon months. Large number
cattle population with other livestock generally feed on mangrove seeds along
the sandy shores (Fig. 11.7).
The wave beaten compact mud banks on the foregrounds of high tide shoreline do not provide the anchorage facilities for mangrove seeds in the dynamic
current condition. Tidal dispersal of mangrove seeds cannot reach the supra tidal
flat affected by drainage loss, particularly in the inner parts of islands away from
channels and shorelines. Other activities like crab potting, clay mining, and
unscientific netting across channels and intertidal flats also disturb the process of
seed anchorage. Mangrove trees in the sapling stage are also affected by insect
A.K. Paul et al.