Quantification of Historical Riverbank Erosion and Population Displacement Using Satellite Earth Observations and Gridded Population Data

Abstract

Riverbank erosion in Bangladesh is a significant hazard, recurring annually and causing loss of homes, land, and livelihoods. Each year, thousands of people are displaced as a result. Given the urgency of mitigating extreme erosion and preventing further displacement, it is imperative to accurately quantify the magnitude and severity of this phenomenon. With an aim to assess the spatiotemporal changes in riverbank erosion and its impact on population displacement, this study used multi-temporal Landsat imagery from 1990 to 2020. To evaluate the impact of riverbank movement on population displacement, this study utilized gridded population data. The analysis revealed that the region has experienced extreme erosion over the past three decades, with the central region exhibiting the highest erosion rates (-128.5 m/year). More than 50% of transects are experiencing high erosion rates (> 50 m/year). The analysis also revealed that over three decades, more than 11% of transects experience continuous erosion, with the central region being the most affected (44%). Additionally, findings indicate that thousands of individuals have been displaced due to severe erosion. The insights gained from this study will help policymakers in formulating effective mitigation and adaptation strategies tailored to the unique challenges of this region.