Bulletin of Geography. Physical Geography Series, No. 16 (2019): 99–114 http://dx.doi.org/10.2478/bgeo-2019-0007 © 2019 Nicolaus Copernicus University in Toruń. All rights reserved. © 2019 Sciendo (De Gruyter Company) (on-line). ISSN 2080-7686 Bulletin of Geography. Physical Geography Series 2019. This is an Open Access article distributed under the terms of the Creative Commons Attribution- -NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Ujwal Deep Saha * a , Soma Bhattacharya Vivekananda College for Women, India * Correspondence: Vivekananda College for Women, India. E-mail: ujsaha.90@gmail.com a https://orcid.org/0000-0002-0225-7710 Abstract. The varied physiography, incidences of high seasonal discharge, infuences of neo-tecton- ic activity and the young geological foundation with less consolidated cohesive and non-cohesive sediment have left the Himalayan foreland basin a formidable ground, where silt-laden rivers tend to migrate frequently. A set of maps prepared after 1764, space photographs captured in 1970 and current satellite images from 2015 and 2017 were studied to reconstruct the fuvial dynamics of the Torsa River on the foreland basin of Sikkim-Bhutan Himalaya considering a time span of nearly 250 years. Evidence collected from colonial literature, the above-mentioned satellite images and a feld survey, were combined to verify results taken from the old maps used as the base of the study. The application of satellite remote sensing and analysis of the topographic signatures of the palaeo-cours- es in the form of the palaeo-levee, abandoned courses and ox-bow lakes were the major operation- al attributes in this study. As a consequence of the channel migration of Torsa River since 1764, the historical foodplain of Torsa has been topographically marked by beheaded old distributaries, a mis- ft channel system and the presence of abandoned. Morphometric changes in the old courses, ma- jor food events and neo-tectonic activity guided an overall trend of channel migration eastwards and has led to a couple of channel oscillation events in the Torsa River over the last 250 years. The mechanism of the avulsion events was thoroughly driven by sedimentation-induced channel morpho- metric changes and occasional high discharge. Reconstructing the channel shifting pattern of the Torsa River on the Himalayan Foreland Basin over the last 250 years Key words: Channel oscillation, colonial literature, Himalayan foreland, remote sensing Introduction Te fuvial environment of any particular river on the Himalayan foredeep basin is continuously ad- justing its character as the river encounters a cer- tain change in the morphodynamic domain of the controlling variables. Tis is caused by the gradient dropping considerably between the mountainous stretch and the foreland plain. Tis has substantial- ly contributed the rivers being both highly dynam- ic and hyper-avulsive. Te rate of migration is so rapid that the rivers can be transitive at a temporal scale of a few decades to a century (Chakraborty and Ghosh, 2010; Jain and Sinha, 2004; Sinha and Ghosh, 2011; Roy and Sinha, 2005; Jana, 2006; Chakraborty and Dutta, 2012; Mukhopadhyay, 2014). At such rates of change, combining old maps with recent satellite datasets can provide valuable discernments of the channel dynamicity at a mod- erate temporal scale for a couple of centuries (Pass-