Are the Sundarbans, the World's largest mangroves region under threat?—An ecosystem‐based geospatial approach to assess changes past, present, and future in relation to natural and human‐induced factors

Abstract

AbstractThe World's most extensive mangrove region, the Sundarbans ecosystem, is highly biodiverse but severely stressed. Past, present, and future potential changes in Sundarbans mangroves have been assessed from multi‐temporal satellite data of 1980, 2000, and 2020, elevation data, and topographical maps using geospatial techniques, digital shoreline analysis system, land change modelling, and ground truth verification. The mangrove loss was 16,025 ha between 1980 and 2020 and is predicted to be 22,286 ha between 2020 and 2050. Major changes were observed in mangroves, waterbodies, mudflats, agriculture, and aquaculture. The shoreline change by endpoint rate indicated the erosion rate by 5.81 m yr−1 in 2000–2020 compared to −0.90 m yr−1 in 1980–2000. The weighted linear regression indicated the average erosion and accretion rate of −5.96 m‐yr −1 and 4.92 m yr−1, respectively, with erosion in 76% of transects and accretion in the remaining 24% between 1980 and 2020. A sea‐level rise by 1 m will inundate 17,486 ha of mangroves. The finding revealed the dynamic nature of mangroves, past and expected future loss, the severely eroding transects, hotspots, and the consequences of mangrove loss on depending the population. As fringe mangroves will be at greater risk, speedy measures are needed to stabilize the highly eroding regions.