Storm surge hazard assessment of the coastal community in Legazpi City, Philippines

The Philippines is hit by approximately 20 tropical cyclones per year, wherein an average of 10 are tropical storms/typhoons (Cruz, 2016). The country, being an archipelago, consists of numerous coastal communities exposed to these tropical storms. The coastal communities of Legazpi City, based on news articles published, have been identified to be vulnerable to storm surges. Using the modelling software DELFT3D-FLOW coupled with DELFT3D-WAVE, typhoons with a 5, 25, 50 and 100 year return period, and a typhoon with Haiyan strength characteristics, were projected onto these coastal communities to identify which areas are most at risk to storm surges. The 11 tracks, both historical and theoretical, considered in the simulations were either passing directly or nearby Legazpi City. Topographical and hydrological features unique to each area, land use, elevation, barriers-- both natural and artificial, and river discharge were factors incorporated in the simulations. In this study, the effect of the typhoon\u27s track to the water displacement, subjected onto the considered coastal communities, was assessed. From the results of the simulations, hazard maps were created based on typhoons with 25 year return period and Haiyan strength characteristics. Hazard maps were generated to be able to visualize better the hazard posed onto the inhabitants of these communities. From these hazard maps, it was observed that the storm surges affect mostly the coastal communities of northern areas of Legazpi City