Abstract

Impacts of soil erosion in an ungauged wetland catchment

Author(s): Bhaskar J.Das, S.K.Singal, Ranvir Singh, M.P.Sharma

Deeporbeelwetland is a permanent freshwater lake in the former channel of the River Brahmaputra located in the Assam state of India. It is a large natural wetland having great biological and environmental importance and is the only Ramsar site in the state. One of the major threats faced by the wetland is is erosion in the catchment and subsequent silt deposition. The paper deals with the estimation of the annual soil loss from the wetland catchment due to interrill and rill erosion in the year 2005 and comparison with that of the base year (1972).An attempt has also beenmade to identify the main causes responsible for the changes in the annual soil loss rate. The net sediment deposition into the wetland has also been computed as which is only about 32%of the soil loss due to interrill and rill erosion from the catchment. The temporal changes in the annual soil loss rate can be attributed mainly to the change in land use and variation in average annual rainfall and hence in variation in Rainfall Erosivity Index (R). Sediments trappment through afforestation, construction of check dams parallel to shoreline, reduction in hill cutting and quarry operations in wetland catchment have been suggested as conservation measures for improving the health of wetland.