Delft3D Storm Surge Simulation of Typhoon Haiyan for Projection of Coastal Inundation in the Visayas Islands, Philippines

Abstract:

The Philippines is geographically prone to tropical cyclones with an annual average of 20 typhoons entering the country’s area of responsibility. On 08 November 2013, a Category 5 Typhoon Haiyan with maximum one-minute sustained wind speed of 315 kph, hit the central area of the archipelago. The damage from the typhoon reached two billion US dollars with 6,300 reported casualties. The adverse impacts of possible future storm surge events in the Philippine archipelago specifically in the Visayan region can only be mitigated if a storm surge model that will include the inundation of the coastal areas is generated. The hydrodynamic modeling software, Delft3D, was used in the storm surge simulation of the Visayas Islands. An overall model of the Visayas with a coarse grid cell size was nested to a detailed model on hardly stricken populated areas with a 10-m per pixel resolution Digital Elevation Model and General Bathymetric Chart of the Oceans bathymetry. Due to lack of observed water level data during the onslaught of Typhoon Haiyan, the overall Visayas model was calibrated by simulating previous typhoons with recorded data acquired from tide stations. Several simulations were carried out to generate farthest possible inland incursion of storm surges. This was done by translating the actual typhoon track vertically and horizontally with a specified increment. The output of the study is a storm surge inundation map that can be used to determine safe zones for development of infrastructure near coastal areas. The storm surge inundation map can also be used as basis for disaster preparedness plans of coastal communities threatened by approaching typhoons.