Assessing channel migration dynamics and vulnerability (1977–2018) of the Torsa River in the Duars and Tal region of eastern Himalayan foothills, West Bengal, India

Abstract

Channel migration is perhaps the most rampant quasi-natural hazard that is commonly experienced in the eastern Himalayan foothills of Duars and Tal region, India. The present study is dealt with the Torsa River, which is situated in the Duars and Tal region. The study aims at the changing rate of channel migration and vulnerability of the Torsa River in Duars and Tal region on spatial and temporal basis using geospatial methods. The changing course of the Torsa River was detected using remote sensing and GIS since 1977–2018 (42 years). USGS Landsat MSS, ETM, OLI_TRIS sensor data (1977, 2010 and 2018) were considered to demarcate the chronological changes of the river course. Normalized Difference Water Index was used to extract the surface water bodies. Sixteen cross sections have been considered to delimit the river course migration pattern. The results showed that the Torsa River course has been migrating towards the right bank at different places of the study area. In the downstream of Patla Khawa Protected Forest, the continuous lateral migration of the river Torsa and associated river bank erosion invited the loss of agricultural land and socio-economic vulnerability in most of the villages of Cooch Behar I, Cooch Behar II and Mathabhanga II blocks of Cooch Behar district, West Bengal. Therefore, the present study may be helpful for ensuing suitable site specific management options which may check future river bank erosion as well as loss of livelihood and properties.