Sea level rise and flooding in Bangladesh

Sea level rise caused by climate change foreseen in the 21st century will increase damage by flooding in low and flat areas like Bangladesh. This paper provides some forecasts on the monthly effects of the sea level rise on the flooding area in Bangladesh based on a hydrological model with a differential equation. The increase in the flooding area in Bangladesh is estimated to be about 1.5% in rainy seasons and over 5% in dry seasons (the floods will be drawn out into dry seasons) for every 1 m rise in sea level. Back-up estimation is also provided by a simpler model, in which the whole area is sunk, sustaining its configuration, by the same amounts as the future sea level rises. The obtained annual average increases in the flooding area are close to those obtained by the differential equation model. It must be remarked, however, that the estimation in this paper is based on a rough approximation of the topography of Bangladesh, which is moving every year by flooding and would hardly be measured precisely.