Channel Confluence Dynamics in the Lower Chel River System, Eastern Sub-Himalayan West Bengal, India

Abstract

In the present study channel confluence movements of two confluence points namely, Chel-Kumlai rivers’ confluence and Chel-Neora rivers’ confluence in the lower Chel-Neora river system has been analyzed using multi temporal Landsat images and topographical sheets. The study area is a part of region popularly known as ‘Dooars’ which falls in the zone of transition between the dissected outer Himalayan hill surface and the gently rolling Teesta-Brahmaputra plains, and is famous for notorious incidents of channel avulsion and river capture activities. This study tries to elucidate various fluvial processes responsible for confluence dynamics. The temporal scale of the study spans 62 years (1955-2017) and establishes the fact that the confluence points of the rivers have shifted both upstream and downstream in much variable rates during the assessment period. Avulsions, cut-offs, aggradations and river capture has been identified as controlling processes for such confluence dynamics.