Storm surge modelling with geographic information systems: Estimating areas and population affected by cyclone Nargis

A methodology has been developed to model storm surges during cyclones, and to estimate affected areas and population with Geographical Information System (GIS). Surge profiles were derived from the calibrated wind velocity distribution by using regional regressive relationships between the wind velocities and surge heights. Discretised forms of the calculated surge profiles were entered in GIS analysis to estimate affected area and population. This approach was compared with a simple and more common GIS approach that uses a constant storm surge height. The study also considers the effects of different time advisories on the estimation of affected population and areas. It was found that for the cyclone 'Nargis', the affected area and population could be estimated with accuracies of 60 and 20%, respectively, for advisories issued when the cyclone centre was more than 600 km from the landing point. These accuracies were 80 and 60%, respectively, when the cyclone centre was within 200 km of landfall. The proposed methodology can be helpful for early warning systems and disaster risk management due to its simplicity and speed as well as in cases where minimal information on the affected areas and population is available such as in the case of cyclone Nargis in Myanmar.