Estimating bank line migration of the Brahmaputra river in the Middle Brahmaputra floodplains of Assam, India using Digital Shoreline Analysis System (DSAS)

Abstract

The process of erosion as an inevitable and disastrous mechanism has caused migration of bank lines of rivers globally. In its middle reaches, the Brahmaputra River has eroded many pockets of land, eventually leading to drastic bank line shifting. This study aims to analyze the bank line migration of the Brahmaputra river in the Middle Brahmaputra floodplains of Assam, India, over a period of 30 years (1990-2020) and forecast their future positioning. The study was carried out using digital shoreline analysis system (DSAS). End point rate (EPR) was used to estimate bank line migration over three decades (1990-2000, 2000-2010 and 2010-2020). Both end point rate (EPR) and linear regression rate (LRR) were used for calculating long-term migration from 1990 to 2020. The findings revealed that bank line migration was more prominent along the river’s south bank and the river channel was observed to be migrating in a southward direction. The average shift of the right bank of the river was around -8.15 m/y, 11.83 m/y and -4.5 m/y during 1990-2000, 2000-2010 and 2010-2020 respectively. The left bank of the river showed an erosive trend with an average positional shift of -57.02 m/y, -53.65 m/y and -38.66 m/y during 1990-2000, 2000-2010 and 2010-2020 respectively. The forecasting of the bank lines for 2030 and 2040 showed that the river would likely continue to erode its banks leading to channel widening. The study demonstrated the severity of riverbank erosion and bank line migration processes in the Middle Brahmaputra floodplains. This work might help policymakers find solutions to protect the invaluable lands and lessen the vulnerability of the affected population.

Decoding Chambal River Shoreline Transformations: A Comprehensive Analysis Using Remote Sensing, GIS, and DSAS

“…It can cause extreme poverty in the region [2]. Therefore, effective mitigation techniques are needed to protect the river and riverine lands from erosion [35]. The unsustainable local sand mining practices lead to a loss of extracted bed aggregates that cannot be compensated for by natural sediment supplies from the upper reaches of rivers [36].…”