Environmental Risk Assessment: A Geomorphic Investigation over the Bolpur-Santiniketan-Illambazar Lateritic Patch of Birbhum District, West Bengal, India

A proper geomorphic study of a region can be useful in understanding past and present environmental circumstances and analyzing potential environmental risks. Careful analysis of morphodynamic processes and existing diagnostic landforms reveal several aspects about the origin, characteristics and possible pattern of morpho-climatic interactions on the landscape over temporal scale, which helps significantly in proper terrain evaluation from societal welfare and integrated management point of view, including environmental risk assessment and disaster management. This paper has made a thorough geomorphic investigation based on intensive fieldwork and multi-sourced remote sensing data to characterize the lateritic soil profile and landforms of the study area in respect to their morphology and Physico-chemical properties at the different sites of land degradation to understand the outcome of morphoclimatic interactions on the landscape over time, and to evaluate the severity of operation with pedo-geomorphic constraints in the lateritic environment for sustainable management purposes. It is found that the region is highly sensitive to weathering, mass movement and denudational activities, mainly caused by rainwater erosion which has resulted into varied landforms including well-developed rills and gullies, lateritic ridges, isolated residual hills etc and generated a unique identity to this part of the lateritic region. The study also suggested a model for the development of geomorphic landforms in a lateritic terrain based on past and present morphoclimatic interactions, nature of physiography, lithology, soil characteristics and other biotic and abiotic elements. The region is also found to be a subject to moderate to severe land degradation due to the active geomorphic processes in operation in tropical regions and inherently poor physical and chemical formation of the existing soil profile and radical conversion of land uses as observed at cadastral level leading towards irresistible desertification. Annual topsoil loss amount has been calculated using the Universal Soil Loss Equation method. Three sample Mouzas namely Ballavpur, Shyambati and Chawpahari jungle have been assessed to be having 36.98%, 71.42% and 61.73% of degraded land in respect to their total village area. Various conservative measures like stabilization of gully heads and beds through reforestation and afforestation with cutting earth plug, brush fills and check dams; improvement of the irrigation network, suitable dryland farming etc. have been recommended to arrest the desertification process.