A Cyclone Induced Storm Surge Forecasting Model for the Coast of Bangladesh with Application to the Cyclone SIDR

The coast of Bangladesh has a specialty in terms of high bending and many off- shore islands. Incorporation of the coastline and island boundaries properly in the numerical scheme is essential for accurate estimation of water levels due to surge. For that purpose a numerical scheme consisting of very fine mesh is required along the coastal belt, whereas this is unnecessary away from the coast. In this study, a fine mesh scheme covering the coastal belt and islands has been nested into a coarse mesh scheme covering up to 15 N latitude in the Bay of Bengal. For the existence of so many small and big islands and also for high bending of the coastline along the Meghna estuary, a very fine mesh scheme for the region between Barisal and Chittagong is again nested into the fine mesh scheme. A vertically integrated model is developed in Cartesian coordinate system to solve the shallow water equations using semi- implicit finite difference technique for computing surge associated with storms. The developedsystem is applied on a severe cyclonic storm ’SIDR’ that hit Bangladesh on 15th November, 2007. The computed water levels are found to be in good agreement with those observed.