Channel avulsion in the Torsa River course and its response to topographic and hydrological controls on the Himalayan Foreland Basin

Abstract

This study intends to scrutinise the style and mechanism of the avulsion events in the Torsa River flowing across the Himalayan Foreland Basin (HFB) through analysing its response to the topographic and hydrological controls. A scientific investigation has been done planting the major thrust on the process geomorphological approach with an obligatory amount of quantification of the process and associated parameters. The investigation is heavily dependent on the available multi-temporal satellite images, set of available hydrological datasets and on-field survey of the topography and geomorphic markers related to past avulsion events in Torsa River between 1968 and 2017. The planimetry of avulsion and the avulsion style ratio has been applied to the occurred avulsion events in the course of Torsa during the said duration to study the underlying mechanism and associated sensitiveness to the given environmental setup. The topographic factors were found as an important controller of the avulsions in the course of river Torsa as the nature of the fluvial process and the physical setup differs significantly over the varied physiographic extents on the HFB. The studied avulsion events were found of annexation type and irrespective of the planform character, a tendency of forming a straighter course corresponding to topographic aptness. The style of avulsion associated within a hyper-avulsive perennial river, Torsa, on the Himalayan Foreland Basin. The underlying mechanism of channel avulsion in the course of Torsa over the different physiographic extents ( i.e., Piedmont and Northern plains). A process response analysis for the avulsion events with its sensitivity to hydrological and floodplain topographic components. The style of avulsion associated within a hyper-avulsive perennial river, Torsa, on the Himalayan Foreland Basin. The underlying mechanism of channel avulsion in the course of Torsa over the different physiographic extents ( i.e., Piedmont and Northern plains). A process response analysis for the avulsion events with its sensitivity to hydrological and floodplain topographic components.