Wetlands in Deepor Beel

DIPOR (DEEPAR) BEEL Guwahati

Location: south of the Brahmaputra river in Kamrup district, 10 km southwest of Guwahati, Assam
Area: 4000 ha
Altitude: 53 m
Biogeographical province: 4.9.4
Wetland type: 14

Description of site: A permanent, freshwater lake with abundant aquatic vegetation in a former channel of the Brahmaputra river, now to the south’of the main river southwest of Guwahati city. Dipor beel is one of the largest of many such “heels” in lower Assam. At maximum flooding, it is about four metres deep; during the dry season, the depth drops to about one metre. The main sources of water are the Basistha and Kalmani rivers and local monsoon run-off between May and September. The beel drains into the Brahmaputra river five km to the north, through the Khonajan channel. About half of the beel dries out during the winter months, and at this time, the exposed shores are converted into rice paddies to a width of up to one kilometre. National Highway 37 passes close to the northern end of the lake, and the Gorhbhanga Reserved Forest, Chakordew Hill, and Chila Hill lie to the south

Climatic conditions: Humid, tropical monsoon climate with a prolonged monsoon season from May to September, a relatively cool, dry winter, and a pre-monsoon period in March-May with occasional storms. Temperatures range from 10.6° to 32.0°C

Principal vegetation: The dominant aquatic plants include Eichhornia crassipes, Pistia stratiotes, Ottelia alismoides, Lemna minor, Potamogeton crispus, Vallisneria spiralis, Hydrilla verticillata, Ipomoea reptans, Azolla pinnata, Spirodela polyrhiza, Eleocharis plantaginea, Nymphaea albea, N.rubra and Sagittaria sagittifolia. The giant water lily (Euryale ferox) also grows here. The lake shore vegetation includes Eupatorium odoratum, Achyranthes aspera, Cyperus esculoentus Phragmites karka, Vitex trifolia, Accium basilium, Saccharum spontaneum, and Imperata arundinacea. Dominant tree species in the nearby deciduous forests include Tectona grandis, Ficus bengalensis, and Bombax malabaricum. Most of the surrounding areas are under cultivation, chiefly for rice Land tenure: State-owned (Fishery Department, Government of Assam). Surrounding areas are privately owned, except for the Gorbhanga Reserved Forest which is state-owned

Conservation measures taken: The Government of Assam vide Gazette Notification No. FRW.1/80/26 declared 414 ha of the beel area as a Sanctuary (Dipor Beel Sanctuary). Shooting and bird-trapping are prohibited by law, but enforcement is poor.. The area is patrolled by the Fishery Department

Conservation measures proposed: Saikia and Bhattacharjee (1987) have proposed that the entire beel be notified as a bird sanctuary.

Land use: Fishing, illegal trapping of birds during winter, collection of Nymphea nuts and rhizomes of other aquatic plants for human consumption, collection of Euryale ferox seeds for industrial purposes, collection of fodder for domestic livestock, and cultivation of rice during the dry season. Large numbers of domestic livestock graze on the lake shore when water levels are low. Rice is cultivated all around the wetland. A brick factory and several saw-mills have have been established at the beel, and there are many permanant and temporary human dwellings in the vicinity

Possible changes in land use: There is likely to be an increase in human settlement in the area because of an expansion of industry near the beel. The city planners in Guwahati have recently proposed that the beel be used for the disposal of domestic sewage from the city

Disturbances and threats: The intensive fishing activities, pursued both by day and by night, cause a considerable amount of disturbance, and there is heavy hunting pressure on waterbirds. Large numbers of waterbirds are netted illegally during the winter months (December to March) for sale in local markets. The forests in the catchment area to the south are being felled to supply timber for the saw-mills, resulting in increased erosion which, in turn, is causing rapid siltation in the beel. Pesticides and fertilisers are widely used on adjacent agricultural land, and enter the lake in run-off. The fertilizers have accelerated europhication, and infestation with Eichhornia crassipes is now becoming a serious problem. Settlements and permanent agriculture are steadily encroaching on the wetland and reducing the extent of the marsh vegetation. A recent government proposal to dig a canal from Guwahati City to the beel to dispose of the city’s sewage would, if carried out, have disastrous effects on the wetland ecosystem The North East Frontier Railway is planning to construct a railway line through the beel area. Land has already been acquired and construction work is in progress. According to the Institute for Scientific and Technological Research (INSTER), the railway line, related infrastructure, and the increased human nigra, Tadorna ferruginea, Mergus merganser and Ibidorhyncha struthersii. Other noteworthy species associated with the wetlands include Pallas’s fish-eagle, (Haliaeetus leucoryphus), swamp partridge, (Francolinus gularis) , Bengal florican (Houbaropsis bengalensis), crested kingfisher (Leryle Lugubris). There is an extremely large winter roost of swallows and martins (Hirundinidae) on the southern edge of the Park. The following wetland-dependent faunal species that have protected status (i.e. listed in Schedule I of the Indian Wildlife (Protection) Act, 1972), are found in Manas: fishing cat, Indian rhinoceros, wild buffalo, and swamp deer among mammals; osprey among birds; and Indian pond terrapin, sawbacked terrapin, Assam roof turtle, flapshell turtle, chitra turtle, and water monitor among reptiles The Manas river still supports a small population of the endangered gharial (Gavialis gangeticus)