Exploring geospatial changes of wetland in different hydrological paradigms using water presence frequency approach in Barind Tract of West Bengal

The Barind tract of West Bengal is composed with old alluvial soil, relatively undulating plain with good number of riparian wetlands. The main source of water of these wetlands is rain water and inundated water from river because most of the natural wetlands are located alongside the river. Under this condition any kind of river flow modification may influence the present wetlands condition. A good number of dam/reservoirs have been constructed on river Atreyee, Punarbhaba, Tangon etc. and it causes flow modification in those rivers in their downstream. The main objective of this paper is to find out the consequence of such river flow modification on areal extent of wetland, seasonal dynamics of wetland, temporal trend and their vulnerability. For doing this work Landsat image of premonsoon and post-monsoon season since 1988-2016 have been collected from USGS website. After that water presence frequency approach is used for wetland mapping and detecting change in pre and post dam regime. From the analysis it is found that in post dam condition both quantitative and qualitative degradation are being happened and their rate varies in different interfluves zones. It is also found that the degree of vulnerability has been increased in post dam condition. Considering the ecological values and their capability of livelihood support scientific delineation of wetland boundary according to their degree of vulnerability is essential.