Comparative numerical simulation of storm surge inundation characteristics along the dynamic east coast of the Meghna estuary in Bangladesh

Abstract

ABSTRACT Tropical cyclone (TC) is considered as the most dangerous and devastating hydrometeorological natural hazards in the coastal regions. On average, one severe cyclone strikes Bangladesh coast every three years. On the other hand, under significant sediment discharge from the Ganges-Brahmaputra-Meghna (GBM) River system (1.0 ~ 2.4 billion tons/year), Bengal delta dramatically changes its shorelines and bathymetry and has been gaining about 400 km2 land at the eastern part of the Meghna Estuary for the last twenty-seven (1991–2018) years. This study aims to investigate the impact of morphological changes on storm surge induced inundation characteristics on the newly reclaimed coastal lands along with different hypothetical land elevations and Sea level Rise (SLR) scenarios. Five different cyclone tracks are used to generate different cyclonic scenarios with the same strength as TC-1991. This study involves the application of the Delft-3D numerical model and ArcGIS to simulate, calculate, and visualize inundation. The results show that inundation heights strongly depend on the cyclone tracks even if the strength (wind speed and pressure drop) remains the same for all tracks. Also, with the accretion of lands, the inundation depth and extent will decrease at the mainland but increase at the accreted lands and the offshore islands, while with higher land elevation of the accreted lands, it will decrease. With SLRs, the offshore islands and accreted lands are more susceptible than the mainland. The impact of the all over land along with a 1.0 m Sea Level Rise (SLR) on the inundation depth and extent pattern will strongly depend on the elevation of the accreted lands.