Identification of storm surge vulnerable areas in the Philippines through the simulation of Typhoon Haiyan-induced storm surge levels over historical storm tracks

J P Lapidez,K M Cabacaba,V Malano,A M F Lagmay,L Dasallas,J Santiago,J K Suarez,L A Gonzalo,J Tablazon,M M A Ramos

doi:10.5194/nhess-15-1473-2015

Abstract

Abstract. Super Typhoon Haiyan entered the Philippine Area of Responsibility (PAR) on 7 November 2013, causing tremendous damage to infrastructure and loss of lives mainly due to the storm surge and strong winds. Storm surges up to a height of 7 m were reported in the hardest hit areas. The threat imposed by this kind of natural calamity compelled researchers of the Nationwide Operational Assessment of Hazards (Project NOAH) which is the flagship disaster mitigation program of the Department of Science and Technology (DOST) of the Philippine government to undertake a study to determine the vulnerability of all Philippine coastal communities to storm surges of the same magnitude as those generated by Haiyan. This study calculates the maximum probable storm surge height for every coastal locality by running simulations of Haiyan-type conditions but with tracks of tropical cyclones that entered PAR from 1948–2013. One product of this study is a list of the 30 most vulnerable coastal areas that can be used as a basis for choosing priority sites for further studies to implement appropriate site-specific solutions for flood risk management. Another product is the storm tide inundation maps that the local government units can use to develop a risk-sensitive land use plan for identifying appropriate areas to build residential buildings, evacuation sites, and other critical facilities and lifelines. The maps can also be used to develop a disaster response plan and evacuation scheme.

Highlights

The water level oscillations, over and above the predicted astronomical tides in coastal or inland bodies of water, generated by the wind forcings from an atmospheric weather system are called storm surges (Murty, 1999)
The specific factors affecting the height of the generated surge are the following: the storm’s central pressure, wind intensity, translational forward speed, storm radius, storm approach angle, coastline geometry, and the local bathymetry (National Oceanic and Atmospheric Administration, National Weather Service, National Hurricane Center, 2014)
Long stretches of coastal areas, concave and gently sloping coastlines contribute to the enhancement of storm surge impacts

Summary

Introduction

The water level oscillations, over and above the predicted astronomical tides in coastal or inland bodies of water, generated by the wind forcings from an atmospheric weather system are called storm surges (Murty, 1999). The specific factors affecting the height of the generated surge are the following: the storm’s central pressure, wind intensity, translational forward speed, storm radius, storm approach angle, coastline geometry, and the local bathymetry (National Oceanic and Atmospheric Administration, National Weather Service, National Hurricane Center, 2014). The resulting flood induced by storm surge is a major cause of casualties and damages to coastal regions. The Philippines, with its 36 289 km of coastlines, is highly susceptible to the ill effects of weather hazards (Yumul Jr. et al, 2011), such as storm surges. The country’s geographical location increases its exposure to storm surge hazard – it lies in the south western part of the Northwest Pacific basin which is considered to be the most active ocean basin, gen-

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