Impact of Dynamic Morphology Change on Storm Surge Disaster Risks along the Meghna Estuary

Abstract

This study focuses on the impact of morphological changes on storm surge disaster risks in coastal areas around the Meghna estuary of Bangladesh. Long term meso scale features of bathymetry change in the target area are first investigated through analysis of shoreline profiles extracted from satellite images. More than 40 shoreline profiles within the past 40 years are extracted from satellite images. Difference of the tidal phaseduring the period when satellite image was acquired is taken into consideration. Based on Cyclone Sidr of 2007, several model cyclones are selected for numerical computations of storm surges around the Meghna estuary. Besides shoreline profiles, ground elevations of the newly accreted lands arealtered in the computation to compare the inundation area, inundation depth and hydrodynamic forces in each case. Results show that(i) 10 to 20 years of morphology change could alter local inundation height of the order of meters; (ii) elevation of newly created land affectsthe inundation time of surrounded area and 3m higher accreted land tends to shorten the inundation time up to 100minutes; (iii) newly created land reduces the damage levels behind itself while it increases the inundation area and height in the area located seaside of itself and (iv) newly created land significantly reduces the stormy waves and hydrodynamic forces especially in the area behind itself.