In floodplain wetland the evaluation of aquatic environment has been implemented as an effective tool for the rapid assessment. Ox-bow lakes i.e. natural wetlands are the abandoned part of the former meander are common features developed in floodplain. The northern portion of Coochbehar district is under the Tarai belt and the southern portion lies under the alluvial plain physiographic region. The Tarai zone is composed of alternate layers of clay and sand, with a high water table that creates many wetlands. Many natural wetlands in the form of ox-bow lakes have been formed in Tufanganj C.D. Blocks which are locally known as beel or baor. These beels are the abandoned channels of Raidak I, Gadadhar, Kaljani, and Mora Raidak River. Due to the geological and geomorphological set up of this region the rivers mentioned above frequently change their course. Topographical, Geomorphological and Geohydrological maps have been used to know the spatial distribution of wetlands and physiographic set up of the region. Many beels have evolved which are ecologically very much productive. With the help of the Oakton multi parameter and WTW DO meter wetland index has been prepared in some of the beels to analyze the physico-chemical properties of wetlands and to assess the ecological importance as well as human intervention. Thermal bands of Landsat image (OLI/TIRS) have also been used to assess the temperature distribution of the land and wetlands. This paper investigates the role of wetland hydrology to evaluate aquatic environment for the wetland assessment in the floodplain regime.

Wetland classification is the primary tool to identify and determine wetland landscapes, but it seems to be very difficult as wetlands are the transitional zone between aquatic boundary and terrestrial boundary. Wetlands are also found in different hydroclimatic and topographic settings. Recently ecological wetland classification focuses on hydrogeomorphic unit to know the physical background of the wetland. In most of the cases, the topographic terms like slopes, flats have been given more importance than the geomorphological terms like ox-bow, floodplain. Floodplain wetlands in the Himalayan foothill region are very dynamic in nature. In Tufanganj C.D Blocks of Coochbehar district, many floodplain wetlands are evolved in the form of ox-bow lakes, meander scrolls and paleochannels. These wetland landform adjustments have been taking place as a result of spatio-temporal changes of rivers. The study focuses on the process-landform relationships and timescales of landform adjustments which is helpful for further wetland classification and management. In collaboration with both the participation of geomorphology community in wetland science and awareness by ecology community, characterizing wetlands as dynamic landscapes will be more eminent for wetland research and management.