EVALUATION OF STORM SURGE BEHAVIOR DUE TO DIFFERENT TYPHOON TRACKS AND WIND SPEEDS ALONG THE COAST OF DAGUPAN CITY, LINGAYEN GULF, PHILIPPINES

Abstract

Every year, an average of 19.4 typhoons traverse the Philippine Area of Responsibility and the country receives around nine landfalling typhoons. These typhoons can generate storm surges along the coasts and cause inundation of coastal communities. Dagupan City is a low-lying city located along the coast of Lingayen Gulf where 30% of its population live in the coastal barangays. As a coastal community located along the head of the Lingayen Gulf where the bathymetry is shallow, Dagupan city is susceptible to storm surges. This study aims to evaluate the storm surge behavior due to different typhoon tracks and windspeeds along the coast of Dagupan City. To achieve this objective, this study implements numerical simulation of storm surges using the Advanced Circulation (ADCIRC) model. A simple methodology is employed by selecting representative historical typhoons and creating synthetic typhoons by shifting the tracks along the latitude. Simulations of typhoons with different typhoon tracks reveal the critical tracks that give highest storm surges in Dagupan City. Finally, storm surges are simulated for windspeed intensities of 60, 80 and 100 knots which are applied to the identified critical tracks. The results of this study show that shifting the typhoon tracks affects the magnitude of storm surges in Dagupan City. Generally, the tracks that pass near the center of Lingayen Gulf generate the highest storm surge along the coast, however, eastward synthetic tracks near the mouth of the gulf can also potentially produce storm surges in Dagupan City. In addition, it is found that typhoon tracks coming from the West Philippine Sea can generate higher storm surges in Dagupan City compared to tracks from the Pacific Ocean. The highest storm surge generated by the representative historical typhoon is 1 m produced by Typhoon Vicki 1998 while a storm surge of 2 m could be potentially generated along Dagupan City by a typhoon with windspeed of 100 knots. The results of this study can be helpful in predicting storm surges for different typhoon tracks and windspeeds which can be used for coastal disaster preparedness in Dagupan City.