Assessing Shoreline Dynamics of Manpura Island (Meghna Estuary in Bangladesh) from 2000 to 2024 Using Remote Sensing and DSAS Techniques

Abstract

Coastal areas in Bangladesh are highly susceptible to climate change due to their geographical location and geological characteristics. To better understand the vulnerability and the dynamic nature of coastal changes, this study focuses on Manpura Island (an offshore island located at the confluence of the Meghna River and the Bay of Bengal), where the impacts of climate change and coastal processes are particularly pronounced. To assess this shoreline dynamic changes, first the island was delineated and analyzed between 2000 and 2024 utilizing GIS and automated computations with DSAS techniques. This study has been broadly assessed based on the Transect-based shoreline change using End Point Rate (EPR), Weighted Linear Regression (WLR), and Linear Regression Rate (LRR). Regarding the erosion and accretion of the island, the result shows that the highest erosion rate recorded was -227.2 m/year, where the peak accretion rate was about 14.5 m/year. The study revealed a net land loss of 26.26 km², with an average annual loss of -1.09 km². Besides, the greatest amount of erosion (10.95 km²) emerged in between 2005 and 2010, and between 2010 and 2015 it accounted as 10.15 km². To support our satellite based investigation, a comprehensive survey was conducted at the field level to validate the findings of the study. A precise assessment of this offshore islands' vulnerability is crucial as Bangladesh coastal areas is frequently affected by the natural disasters. The findings of the study may enable the legislatures, local government, and environmental conservators to take effective coastal management strategies to mitigate further land loss of the island.

The Dhaka University Journal of Earth and Environmental Sciences, Vol. 14(2), 2025, P 87-102