Channel dynamics and geomorphological adjustments of Kaljani River in Himalayan foothills

Abstract

Channel dynamics is a significant geomorphological process that involves the channel migration, erosion-deposition and meandering of an alluvial river channel within its floodplain region. This geomorphic process is often accelerated by climatic condition and human activities which changes this natural process to a quasi-natural hazard. Current research work tries to evaluate the changing behaviour or dynamic nature of alluvial channel by enlightening average length and shape migration. Finally, state of the art techniques in Arc GIS has been adopted to prepare the mouza (village) wise erosion-deposition map by considering highly fluctuating mouzas of the Kaljani River and its adjacent village at the Himalayan foothill region. The primary data source was a series of time-sequential Landsat data of the years 1972, 1980, 1987, 1993, 1998, 2002, 2008, 2013, and 2019 spanning 47 years. Furthermore, we divided total study time into eight groups i.e. 1972–1980, 1980–1987, 1987–1993, 1993–1998, 1998–2002, 2002–2008, 2008–2013, and 2013–2019 for better understanding. During the study period (1972–2019) the average length of migration of the Kaljani River was 742.05 m and the annual rate was 15.79 m/year. Within this time frame of 1972–2019, the shape area migration of the channel was 66.79 km2 and the annual rate was 1.42 km2/year. The total area of bank erosion from 1972 to 2019 equaled 62.74 km2, out of which, 30.07 km2 were on the right bank and 32.67 km2 were at the left bank. Present analysis helps to enhance the effectiveness of planning and management of land resources and ecological balances in these 45 adjacent Mouzas of the Kaljani River. Among the various important causes, tectonic activity, rainfall, floods, and human intervention especially constriction of the embankment along the Kaljani River are the most significant causes for this dynamic changes of River Kaljani. The results of this study therefore, can be used as an important indicator of the vulnerability of the Kaljani River and also provides information about geomorphological instabilities of the study area.