428
amount of mangrove forests now. Land use
includes fi shing, aquaculture, harvest of timber
and fi rewood, honey-gathering and tourism.
About 10,000 fi shermen are engaged in fi shing.
There are many brackish water aquaculture ponds
(‘bheris’). About 50 % of the Sundarbans mangrove forest have been cleared by man during the
last two or three centuries. About 3,400 km of
embankment have been built to prevent the
ingress of salt water.
Population density of WB has exceeded 1,000/
m
2 . Pressure on the endangered mangrove forest
is intense. The forest area of the delta has been
reduced by half over the last 200–300 years.
These are some of the threats to the Sundarbans.
Some of the social and economic values in the
Sundarbans are as follows: (a) Fishes and prawns
caught in this region are sold in the markets of
Kolkata and almost throughout North India; (b)
the mangrove forests and mudfl ats of the
Sundarbans provide vital breeding and nursery
grounds for large population of fi nfi sh, crustaceans, molluscs, etc.; and (c) about 33 % of the
annual catch of Hilsa in WB and Orissa comes
from the Hooghly-Matlah estuary.
The Sundarbans had been declared as an NP
in 1982 and later as a World Heritage Site.
Proposed conservation measures suggest urgent
need for additional land-based studies combined
with remote-sensing techniques in order to determine the remaining area of mangrove forest.
20.3.23.3 Rabindra Sarovar in Kolkata
Rabindra Sarovar is an artifi cial lentic body situated in South Kolkata. It is famous for its scenic
beauty. The Calcutta Improvement Trust (CIT)
had undertaken a programme of extending the
city southwards by acquisition of marshy land
since the second decade of the twentieth century.
Large-scale excavations were undertaken in this
exercise. Eventually, Rabindra Sarovar was developed by 1940 with new roads, parks and neighbourhoods. Many residential settlements were
developed around the lake during the 1950s
mainly to house the immigrants from East Bengal.
The condition of the lake water and its environs deteriorated badly over the years mainly due
to the increase of man-made interventions. The
main issues are the growing eutrophication and
soil erosion along the shores of the lake. Rabindra
Sarovar was declared as a ‘National Lake’ in
1997 under the National Lake Conservation
Programme (NLCP) of the MOEF, Govt. of India
(GOI). A number of studies, in general, were
done, under the NLCP scheme, on the lake ecosystem, on the faunal diversity of the lake and
also on the utilities and management strategies
for the lake. The lake has an approximate maximum length, breadth and average depth of
1,770 m, 286 m and 9.5 m, respectively.
Further, the lake has the following ranges of
physico-chemical characteristics of its water:
temperature 21–33 °C, turbidity 9.58–20.58
NTU, pH 7.97–8.98, DO 5.15–8.60 mg/l and TA
301.33–417.50 mg/l.
20.3.23.4 East Kolkata Wetlands
The East Calcutta Wetlands or East Kolkata
Wetlands (also commonly known as Salt Lake
Marshes) lie at 3 m MSL, between 22° 25′ and
22° 40′ N and 88° 20′ and 88° 35′ E, and are a
complex of natural and man-made wetlands situated east of Calcutta (Kolkata) City boundary in
West Bengal of India. Its area was c 8,100 ha in
1945 which reduced to c 5,000 ha in 1993. The
wetlands’ area includes salt marshes, salt meadows, sewage farms and settling ponds. The wetlands (Plate 20.89 ) are used to treat Kolkata’s
sewage, and the nutrients contained in the waste
water sustain fi sh farms and agriculture. The climate is humid, tropical monsoon. Annual average rainfall is 1,582 mm. Temperature usually
ranges from 9 to 39 °C.
History
Early descriptions (1748) revealed that the salt
lakes had spread over a vast area extending
between the River Hooghly in the west to River
Bidyadhari (now dead) in the east. These wetlands had a luxuriant population of fi shes and
birds. Urbanisation, since 1800s, had resulted in
discharge of untreated sewage and storm water
into these wetlands. This altered their water
characteristics from a highly saline to a predominantly non-saline regime. This, further, led to
siltation of the River Bidyadhari which was offi -
cially declared dead by the Govt. of WB in 1928.
Dumping of solid wastes of Calcutta into the
20 Wetlands of India
amount of mangrove forests now. Land use
includes fi shing, aquaculture, harvest of timber
and fi rewood, honey-gathering and tourism.
About 10,000 fi shermen are engaged in fi shing.
There are many brackish water aquaculture ponds
(‘bheris’). About 50 % of the Sundarbans mangrove forest have been cleared by man during the
last two or three centuries. About 3,400 km of
embankment have been built to prevent the
ingress of salt water.
Population density of WB has exceeded 1,000/
m
2 . Pressure on the endangered mangrove forest
is intense. The forest area of the delta has been
reduced by half over the last 200–300 years.
These are some of the threats to the Sundarbans.
Some of the social and economic values in the
Sundarbans are as follows: (a) Fishes and prawns
caught in this region are sold in the markets of
Kolkata and almost throughout North India; (b)
the mangrove forests and mudfl ats of the
Sundarbans provide vital breeding and nursery
grounds for large population of fi nfi sh, crustaceans, molluscs, etc.; and (c) about 33 % of the
annual catch of Hilsa in WB and Orissa comes
from the Hooghly-Matlah estuary.
The Sundarbans had been declared as an NP
in 1982 and later as a World Heritage Site.
Proposed conservation measures suggest urgent
need for additional land-based studies combined
with remote-sensing techniques in order to determine the remaining area of mangrove forest.
20.3.23.3 Rabindra Sarovar in Kolkata
Rabindra Sarovar is an artifi cial lentic body situated in South Kolkata. It is famous for its scenic
beauty. The Calcutta Improvement Trust (CIT)
had undertaken a programme of extending the
city southwards by acquisition of marshy land
since the second decade of the twentieth century.
Large-scale excavations were undertaken in this
exercise. Eventually, Rabindra Sarovar was developed by 1940 with new roads, parks and neighbourhoods. Many residential settlements were
developed around the lake during the 1950s
mainly to house the immigrants from East Bengal.
The condition of the lake water and its environs deteriorated badly over the years mainly due
to the increase of man-made interventions. The
main issues are the growing eutrophication and
soil erosion along the shores of the lake. Rabindra
Sarovar was declared as a ‘National Lake’ in
1997 under the National Lake Conservation
Programme (NLCP) of the MOEF, Govt. of India
(GOI). A number of studies, in general, were
done, under the NLCP scheme, on the lake ecosystem, on the faunal diversity of the lake and
also on the utilities and management strategies
for the lake. The lake has an approximate maximum length, breadth and average depth of
1,770 m, 286 m and 9.5 m, respectively.
Further, the lake has the following ranges of
physico-chemical characteristics of its water:
temperature 21–33 °C, turbidity 9.58–20.58
NTU, pH 7.97–8.98, DO 5.15–8.60 mg/l and TA
301.33–417.50 mg/l.
20.3.23.4 East Kolkata Wetlands
The East Calcutta Wetlands or East Kolkata
Wetlands (also commonly known as Salt Lake
Marshes) lie at 3 m MSL, between 22° 25′ and
22° 40′ N and 88° 20′ and 88° 35′ E, and are a
complex of natural and man-made wetlands situated east of Calcutta (Kolkata) City boundary in
West Bengal of India. Its area was c 8,100 ha in
1945 which reduced to c 5,000 ha in 1993. The
wetlands’ area includes salt marshes, salt meadows, sewage farms and settling ponds. The wetlands (Plate 20.89 ) are used to treat Kolkata’s
sewage, and the nutrients contained in the waste
water sustain fi sh farms and agriculture. The climate is humid, tropical monsoon. Annual average rainfall is 1,582 mm. Temperature usually
ranges from 9 to 39 °C.
History
Early descriptions (1748) revealed that the salt
lakes had spread over a vast area extending
between the River Hooghly in the west to River
Bidyadhari (now dead) in the east. These wetlands had a luxuriant population of fi shes and
birds. Urbanisation, since 1800s, had resulted in
discharge of untreated sewage and storm water
into these wetlands. This altered their water
characteristics from a highly saline to a predominantly non-saline regime. This, further, led to
siltation of the River Bidyadhari which was offi -
cially declared dead by the Govt. of WB in 1928.
Dumping of solid wastes of Calcutta into the
20 Wetlands of India