Duration of the project : Three Years
Project initiated on : 01.03.1994
Funded by : Ministry of Environment & Forest, Govt. of India.
Introduction:
The State of West Bengal has numerous small and large water-bodies which are among the rich tropical wetland systems of the world. Apart from being a repository of aquatic flora and fauna of this bio-geographic region, these wetlands provide suitable habitat for the resident and migratory waterbirds and contribute much to the socio-economic well-being of the local communities.
These wetlands change due to changes in land use pattern, pollution and lack of scientific management which may lead to complete destruction of these systems. Despite the great sociological, economic and biological importance of the wetlands of the area, insufficient systematic scientific conservation and management studies have been taken up. So an extensive effort is necessary to assess the conservation value and status of wetlands and their associated flora and fauna in West Bengal.
Important parameters studied:
- Geographical features.
- Morphometric features.
- Physio-chemical analysis, such as temperature, Ph, Dissolved Oxygen, light penetration, sedimentation study, fluctuation of water level.
- Biological studies include study on zoo planktons, aquatic vegetation, insects and arthopods, molluscs, fish, birds, reptiles, and other animals.
- Socio-economic study will be made to assess the use of wetlands for fishing and irrigation, human interference, pollution and surrounding population.
Wetlands Covered:
- Satragachi Jheel
- Belanagar Wetland
- Amta Wetland
- Uluberia Wetland
- Mrigala Boro Jala Wetland
- Kolbeel
- Hansmari Char
- Dekol Beel
- Khariberia Bheri
- Nalban Bheri
- Jhaukhali Bheri
- Palta Water works
- Brace Bridge Wetland
- Dabur Char
- Natun Diara
- Bangar Bheel
These wetlands are covered because of their rich potential of biodiversity.
This is a huge 105 page report. So the exhaustive work of only one wetland is given below because it is now a proposed Ramsar Site.
Nalban BHERY:
Nalban Bheri also known as the East Calcutta Wetlands. There are large areas of ponds, marshes and swamps, situated immediately south-east of Calcutta city boundary and located between 22°25' - 22°40' N latitude and 88°35' E longitude. Formerly these wetlands covered approximately 8100 hectares (1945) but now only about 3000 hectares still remain (1955). This swamp is an inter distributaries wetland in the mature delta of river Hooghly and was a vast region of tributaries and distributaries extending between the river Hooghly in the west and river Bidyadhari (now dead) in the east. It also provided important channels for navigation between Calcutta and present days what is today, a part of Bangladesh. The lakes, which acted as spill reservoirs for the Bidyadhari, teemed with fish and birds. With urban development in the early 1800, untreated sewage and storm water began to be discharged into these wetlands, changing their water characteristics from highly saline to predominantly non-saline. This also caused the silting up of the Bidyadhari, which was officially declared dead by the then Bengal Government in 1928.
Dumping of Calcutta's solid wastes in the Salt Lake area still continues and at present, these wetlands sustain the world's largest and oldest integrated resource recovery practice that combines agriculture and aquaculture to utilize the garbage and waste waters of Calcutta metropolis. In the absence of any sewage treatment plants, the entire domestic sewage of the city (estimated to be 680 million liters per day) is discharged into these lakes which act as highly efficient oxy-generation ponds thereby aerating the sewage. The semi-treated, nutrient-rich effluent is then utilized for fish culture and for cultivating vegetables grown on composed solid wastes as well as the paddy fields. Two varieties of paddy are cultivated- Aman and Boro. Aman being sown during the rains and Boro in winter. A large variety of vegetables such as cabbage, cauliflower, gourd and pumpkin are grown on 3200 hectares of garbage substrate. The garbage farms (which form a part of Salt Lake waste recycling system) contribute to round the year supply of vegetables, the production being over 3, 70,650kg per hectare per year and it is estimated to be 148 tones of seasonal vegetables reach the city from the garbage dumps of this area daily. Garbage is deposited in a planned sequence, raising the ground 1-1.5 meters and leaving waterbodies in between dumps to facilitate irrigation of vegetable fields and for growing fish fingerlings on a commercial basis. The sewage-fed fisheries of Salt Lake covered an area of 4685 hactres in 1945 but had shrunk to about 3000 hactres by 1985. These fisheries provide the citizens of Calcutta with fish such as Rohu, Catla, Mrigal, Common carp, Silver carp, Grass carp, Tilapia etc; the production being about 8000 tones per year. Besides, these swamps generate employment opportunities for over 20,000 fishermen, paddy-cultivators, vegetable farmers, rag pickers and people engaged in various forms of waste recycling.
However, extensive reclamation of these wetlands which had its early beginnings in 1865 when a 2.6 sq km area was acquired as a landfill by the municipality is today a major threat to the ecological balance. In addition to landfill activities, there are plans to reclaim the wetlands for urban construction due to the high real estate value of land in such proximity to the city of Calcutta. A major reclamation project was carried out from 1962-67 when 1200 hectors of the swamp was filled with silt dredged from it river Hooghly and converted it into a massive residential complex-The Salt Lake City. Large areas of wetlands were also drained and filled for the construction of the Eastern Metropolitan by-pass in the 1980s. Some wetlands were also converted into paddy fields. The remaining wetlands were under threat from real estate interests in 1991-92 when a "Science City" and an amusement park (named Nicco Park) covering an area of 16.18 hactres was built and plans were made to expand the Salt Lake City by 607.04 hactres and building a zoological garden World Trade Center ground on 55.5 hactres. Although these plans have been suspended by a Court Order for the time being but future threats of reclamation cannot be ruled out.
The vast wetlands of eastern Calcutta used to attract a large number of waterbirds in the past. Earlier records (1748) depict Salt Lakes teeming with fish and birds. Hundreds of waders used to flock here throughout the year to feed and breed in the swamps, and in winter thousands of ducks and geese used to throng the area. Even during the 1960s, scientists of the Zoological Survey of India have recorded 248 bird species from the Salt Lakes, of which 90 were wetland species (50% birds being migratory waterfowl) and the rest 158 species of terrestrial birds. Over the years, as the city expanded itself to this portion and the new Salt Lake City was built, the wetlands vanished rapidly. Now only a fraction of the original remains scattered in small fragments as symbols of days gone by. The only large water body remaining in this area is the Nalban Bheri, just adjacent to the newly constructed Nicco Park and although pisciculture is practiced here and recreational activities like boating is carried out, some waterbirds still come here in all seasons. It is the favourite wintering ground of Shovellers and Tufted Pochards which visit the water body in sizeable numbers. A handful of Gadwalls, Garganeys and Pintails also come along with them. Some other waterbirds like Sandpipers, Snipes, Gulls, Terns, Egrets and Cormorants also occur here throughout the year. A list of waterbirds species recorded in recent years is given below along with their seasonal incidence.
The adjoining Chinta Singh Bheri which used to bring in a large number of waterbirds in the past has been gradually filled up over the years and converted into paddy fields. The other waterbodies in the area being reduced in size (like Captain Bheri, Goltala bheri etc.) no longer attract much waterbirds (except Egrets and Cormorants) and especially no ducks and geese. Indeed, the Graylag goose (Anseranser) which used to visit the Salt Lake Wetlands earlier has not been recorded here in the last two decades.
In conclusion, it may be said that the number of migratory and resident waterbirds in the Salt Lake wetlands have declined over the years. Rapid urbanization and unplanned development, filling and reclamation of wetlands, draining of the swamps with consequent changes in their drainage pattern, eutrophication and weed growth, conversion of wetlands to croplands, fragmentation of existing waterbodies, poaching, excessive pisciculture, boating; pollution from household wastes, domestic and municipal sewage as well as fertilizers, pesticides, detergents and large scale discharge of toxic industrial effluents from several tanneries nearby are some of the causes for the present decline in population of waterbirds in the wetlands of Salt Lake.
NORTH 24-PARGANAS (NALBAN BHERRY) Nalban Bhery is in the North 24-Parganas District.
