An introspect of neotectonic response on channel bars morphodynamic of the rivers in Darjeeling Himalayan piedmont zone, India

Abstract

ABSTRACT The present research focuses on the recent tectonic activities and their effect on quaternary deposition such as channel bars in the 80 km × 50 km river corridor of the Darjeeling Himalayan Foothill Region (DHFR). The active orogeny belt has direct control over the fluvial deposition in the master river systems of Tista, Jaldhaka, and Torsa and their sub-systems of Neora, Murti, Kurti, Lish, Gish, Chel, and Mal. The present research has used some indices like the stream-length gradient index , mountain front sinuosity , valley-floor width to valley height ratio , and especially longitudinal profiles of the river. Channel bar area, longest length, width of channel bar, elongation ratio, relative relief, and relief ratio were calculated to get the introspect of neotectonic response on channel bars morphodynamic. The results on selected 10 channel bars of the upper DHFR depict that they are highly affected by neotectonic deformation. The channel bars of the middle part of the DHFR also have significant morphological signatures of tectonic movements. The reflection of these active tectonics is visible in the channel bars of the lower DHFR. These channel bars show a high rate of aggradation responsible for continuously changing the morphology and morphometry of these bars.