Mapping inundation from sea-level rise and its interaction with land cover in the Sundarbans mangrove forest

Abstract

Abstract The sea level rise (SLR) in the Sundarbans areas is higher than the global-average rate of sea rise, and many studies assume that most of the dry land of the Sundarbans will be inundated by the end of the twenty-first century. This study aims to analyse the amount of dry land that can potentially be inundated by SLR in Sundarbans and the impact under different land cover conditions. We applied geospatial data from a Digital Elevation Model (DEM), four SLR scenarios, and net subsidence data to map future inundated areas and discuss the impacts. Results for the low (35 cm), mid (52 cm), high (70 cm), and extreme (147 cm) SLR scenarios indicate that the Sundarbans landmass area will be flooded up to 40 km2 (1%), 72 km2 (1.8%), 136 km2 (3.4%), and 918 km2 (23%) respectively, under the current net subsidence rate of -2.4 mm/year. Except for the extreme scenarios, the low, mid, and high SLR will result in riverbank and beach areas to be covered by water. Thus, the potential inundation areas of different vegetation cover classes that already exist today (2020) will be of low significance for the low, mid, and high SLR scenarios. We also analysed the sensitivity of the results through station-based SLR data, which fits with the low (35 cm) SLR scenarios under the − 2.4 mm/year subsidence rate. This study concluded that the inundation aspect of SLR would not directly affect the Sundarbans; however, other related threats and anthropogenic disturbances can be major drivers of Sundarbans' degradation by the end of the twenty-first century. The study's findings might contribute to forest management planning and achieving some goals of the Bangladesh Delta Plan.