Palawan, Iloilo most vulnerable to highest storm surges

MANILA, Philippines — Coastal areas in Samar, Leyte, Palawan, Iloilo and Biliran provinces are vulnerable to the highest storm surges that may strike the country, the Department of Science and Technology (DOST) said.

In a study released early this month, scientists of DOST's Nationwide Operational Assessment of Hazards or Project NOAH indicated areas at risk to potentially deadly storm surges, similar to those that swept over central Visayas at the onslaught of super typhoon Yolanda in November last year.

Low-elevation zones with high population density are the most vulnerable to the tsunami-like phenomena triggered by strong cyclones, the study suggested.

Maximum heights may range from 3.39 meters or 11.12 feet to 7.45 meters or 24 feet. This means that a two-story building will be easily inundated by highest abnormal levels of water.

Maximum storm surge heights for the top seven provinces. Project NOAH

Project NOAH also mapped top 30 areas at risk to highest storm surges based on elevation, proximity to the shore and the number of residents.

Maximum storm surge height bubble map for the Philippines. Project NOAH

Data was culled by cross referencing best track data of the Japan Meteorological Agency from 1951 to 2013 to the list of typhoons that entered the Philippine area of responsibility.

The researchers simulated the phenomena by generating 861 hypothetical typhoons using the Japanese bureau's model predicting heights of storm surges generated by inland and offshore tropical cyclones.

The Project NOAH study says that storms central pressure, wind intensity, translational forward speed, storm radius, storm approach angle, coastline shape, and the depth of water in seas, oceans or lakes are factors affecting height of generated storm surges.

"The resulting surging flood induced by a storm surge is a major cause of casualties and damages to coastal regions," it noted.

The Philippines is particularly  susceptible to coastal flooding being an archipelago consisting of 7,107 islands with 36,289 kilometers of coastline.

Geography also plays an important role as the country lies in the southwestern part of the Northern Pacific basin, "considered to be the most active ocean basin generating an average of 26 tropical cyclones per year."

The researchers said that government and citizens avert the effects of an extreme weather event like Yolanda, which killed tens of thousands, by using hazard and inundation maps.

The maps are based on worst case scenarios for every area authorities can use for disaster response plans and evacuation schemes.