A deterministic hazard assessment for storm surge induced flooding: A case study

Coastal flooding due to tropical cyclone generated storm surges has caused considerable damage and loss of life in the North Indian Ocean region including in Sri Lanka. This paper is concerned with a deterministic analysis of the storm surge hazard for the city of Chilaw on the west coast of Sri Lanka, as a case study. The present hazard assessment utilizes a database of historical events of tropical cyclones in the North Indian Ocean region. A statistical analysis of the past events has been carried out to identify an appropriate storm surge scenario. Numerical models comprising a parametric cyclone model and a hydrodynamic model based on shallow water equations have been employed to simulate cyclone wind velocity and pressure fields as well as coastal inundation due to the storm surges. The spatial distribution of the depth of inundation as well as maps of the hazard to population and residential buildings in the study area are presented and discussed.