Channel Avulsion Archives and Morphological Readjustment near the Bhagirathi-Mayurakshi Confluence in the Lower Gangatic Plain, West Bengal, India

Abstract

The morphology of an alluvial channel is a complex response phenomenon adjusted over geologic, climatic and anthropogenic controls and a number of morphologic and hydrologic factors have been involved for scientific and logical investigation. Channel geomorphic forms are the landforms within the landforms up to various extent in different spatial order that are develop according to the acted fluvial forces (e.g. turbulence, helicoidal and convective motions etc.) along with the incorporation of various causal factors i.e. tectonic tilting, channel geometry, sedimentological readjustments and discharge variability. The present study includes surface morphology of the floodplains and the channels avulsive characteristics in the past sixty years using LANDSAT and SRTM data. In this study topographical maps of 1955 help to construct the path to study the history of channel as well as floodplain morphology as there are no satellite data of 1955. Major outcomes of this paper are the Bhagirathi-Mayurakshi confluence shifting criticality, complex meandering pattern of Mayurakshi and Dwaraka River near the confluence, meandering abnormality in the Bhagirathi River and intra-channel formation (crevasse) which has breached right bank natural levee of the Bhagirathi River.

Keywords: Meandering, Avulsion, Floodplain, Confluence, Bhagirathi River, Natural levee, Over bank sedimentation, alluvial deposit