Assessing spatiotemporal trends of riverbank erosion using a GIS-DSAS-based integrated approach

Abstract

Bangladesh’s geography is defined by its extensive river network, comprising around seven hundred rivers that traverse the country. This vast river system is both a key asset and a significant risk, with river erosion displacing over one million individuals annually. Unfortunately, river erosion does not receive adequate attention from authorities. The study aims to quantify the rates of riverbank erosion and accretion over time, using geospatial approach to provide a comprehensive understanding of the spatiotemporal dynamics of riverbank changes in Chandpur Sadar. We used the USGS’s cloud-free Landsat 4–5 TM and Landsat 8 OLI satellite data, with analyses performed using ENVI 5.1 and ArcGIS 10.8. We used the Modified Normalized Difference Water Index (MNDWI) to find riverbanks and the Digital Shoreline Analysis System (DSAS) to look at changes in banklines. DSAS is a powerful tool for analyzing and understanding spatiotemporal trends in shoreline and riverbank changes, making it indispensable for geospatial studies in dynamic environments. This tool measured distance and rate of change by looking at net shoreline movement (NSM) and end point rate (EPR). Over the past three decades, Chandpur Sadar experienced a bankline shift of 63.98 meters per year, with the maximum erosion (a total land area of 13.32 sq. km) occurring between 1990 and 2000. This research demonstrates the value of implementing an integrated GIS-DSAS tool for spatiotemporal assessment of river erosion trends, aiding policymakers in developing sustainable strategies to mitigate erosion-related losses.

Keywords

• Meghna river
• Landsat imagery
• spatiotemporal analysis
• riverbank accretion
• DSAS