Effect of Cyclone Track and Landfall Angle on the Magnitude of Storm Surges Along the Coast of Bangladesh in the Northern Bay of Bengal

Abstract

The position and configuration of the coastal shelf of the northern Bay of Bengal amplify the storm surge height extraordinarily. The low-lying coast of Bangladesh is severely devastated when extreme surges hit the land. However, the influence of track of a cyclone on surge height is not well known. A calibrated numerical model is used to simulate series of storm surges for a severe cyclone by shifting its track position and angle. The cyclonic wind field has been generated using the extreme parameters adopted from historical measurements. Surge heights simulated by the two-dimensional model are compared at selected locations along the coast. It was found that the cyclone with a landfall location at Barguna, a place between the Sundarban and the Meghna Estuary, develops the highest surge of 12.0 m (PWD) at the northeast of the estuary. The magnitude is further amplified to 13.0 m (PWD) when the surge coincides with the high-tide condition; a surge of similar magnitude attacked the coast of Bangladesh in 1876. Change in track orientation shows little influence on surge heights at the eastern coast. However, relatively higher effect was found in the western coast. Surge height distribution has also been presented with respect to local land or embankment elevation for the extreme event. A flood map is produced showing inundation depth in the aftermath of the extreme surge attack. The coastal areas at the northern tip of the upper bay and the western banks of the Meghna Estuary are found to be the most vulnerable locations.