Yolanda (2013) Storm Surges in Tacloban City, Leyte

8 November 2013

On 8 November 2013, Typhoon Yolanda, international code name Haiyan, made landfall in the central Philippine islands region. The 600 km-diameter typhoon Yolanda crossed the Philippine archipelago, bringing widespread devastation in its path. Storm surges were primarily responsible for the 6,190 dead, 1,785 missing and 28,626 injured in Yolanda’s aftermath.

Yolanda Storm Surge, Tacloban City

Top ten cities/municipalities with fatalities caused by Typhoon Yolanda

Yolanda is one of the most powerful typhoons to have made landfall in recorded history, with maximum sustained winds reaching 315 kph (170 knots) with gusts up to 379 kph (205 knots) just before landfall. This makes it equivalent to a Category 5 typhoon on the Saffir–Simpson hurricane scale, which has the capacity to cause catastrophic damage, a high percentage of destruction of framed homes, total roof failure and wall collapse, isolation of residential areas due to fallen trees and power poles, and power outages that could lasts for weeks to months (Lagmay, 2014).

It started as a region of low pressure in the West Pacific Ocean early on 2nd November 2013 and was upgraded to a tropical storm (TS) with the name Yolanda after subsequent intensification. Upon entry of the typhoon into the Philippine Area of Responsibility (PAR), the Philippine Atmospheric Geophysical Astronomical Services Administration gave it a local name of Yolanda. Regular 6 hourly bulletins on the severe weather disturbance were issued by the Philippine weather bureau with short updates given every hour. Typhoon Yolanda made landfall in Guiuan, Eastern Samar on 8th November 2013 at 04:40 AM local time.

By 7th November, storm signal warnings had been raised by PAGASA, including storm surge warnings in many parts of the country. Typhoon Yolanda hit the eastern part of the Philippines on 8th November, following a track heading towards the West Philippine Sea (South China Sea), crossing the majority of the Visayas region at a speed of 40.7 kph (22 knots). Yolanda maintained its structure as it moved over the east central Philippines. JMA observed that the lowest value of central pressure was 895 hPa (very low central pressure means very high wind speed) and typhoon intensity increased from very strong to violent.

In terms of wind speed, the Joint Typhoon Warning Center touted Yolanda as the most intense tropical cyclone in the world for 2013. As Typhoon Yolanda traversed through the country, it caused damage to houses and infrastructure, flooding in low-lying areas, landslides and storm surges. Initial simulations reveal storm surges to have inundated an estimated 98 km in Leyte and 93 km in Samar, two of the most devastated islands in the Philippines. Other coastal areas in the central Philippines region also experienced floods due to storm surges. Super Typhoon Yolanda is the deadliest typhoon ever to hit the Philippines in recent history leaving 6300 dead, 1061 missing and 28,689 injured (Lagmay, 2014).

The storm surges of Yolanda were predicted two days in advance with a complete list that was broadcast over media the night before Yolanda made landfall. Unfortunately, despite the advanced warnings, these were not translated into appropriate action in every coastal village in the Central Philippines region.

Although communication of storm surge impacts could have been made better, it was not enough to have mitigated the Yolanda disaster. There were those who heeded warnings but they too perished in evacuation centers in Tacloban, Leyte.  The raging sea also overwhelmed even weather scientists, those already well versed with deadly storm surges.

Critical to any action to prepare and prevent disasters are reliable hazard maps. Although specific warnings in places likely to be hit by 4-5 meter storm surges were provided, it was not sufficient to elicit the appropriate response.  These storm surge warnings only provided absolute values in a relative landscape.

How far inland should one go to escape death from storm surges? Coastal landscapes vary and assuming people understood storm surges, still, nobody could have responded appropriately without accurate hazard maps. Moving 100 meters or even 1000 meters inland from the coastline would seem enough, but not quite. Yolanda storm surges entered as far as 2 km inland. In Tacloban, 70% of the evacuation centers were inundated by the deadly incursion of the sea because existing hazard maps did not show the storm surge hazard accurately (Lagmay and Kerle, 2015).

Map of evacuation centers in Tacloban hit by the storm surges during Typhoon Yolanda. (Lagmay, 2014)

Map of evacuation centers in Tacloban hit by the storm surges during Typhoon Yolanda. (Lagmay, 2014)

Tacloban, Leyte

Tacloban was the city hardest hit during the devastation of Typhoon Yolanda. The super typhoon barreled through the provincial capital, affecting the 221,174-strong population, rendering 2,646 dead and 701 missing due to storm surges, strong winds, and heavy rainfall (NDRRMC, 2014).

Three days prior, the then two-month-old Storm Surge Hazard Mapping Team of Project NOAH started running simulations to predict the storm surge heights in the area using the Japan Meteorological Agency (JMA) model and WXTide. On 7 November, they produced a list of areas that will experience storm surges with the corresponding predicted height and estimated time of maximum surge. On this list, Tacloban had the 3rd highest, with 4.5 meters (14.8 feet) storm tide height. Unfortunately, this list of storm surge heights did not translate well despite early warning, as the storm surge maps we have today were not yet completed at the time.

Tacloban residents were used to typhoons, but according to some interviews, they were reportedly caught by surprise by the deluge coming from the sea. Several concrete structures where residents usually take shelter in were completely washed out by the surge. The Astrodome was also flooded with storm surges, drowning several people while others climbed up the bleachers to safety. This event stands out in the history of Tacloban as the deadliest event in recent history.

Estancia and Carles, Iloilo

The municipality of Estancia, Iloilo (population 42,666) was predicted to have a storm surge height of up to five meters. The actual storm surge was recorded at four to five meters, killing 52 people. The effects of Typhoon Yolanda in the municipality were exacerbated by an oil spill from a National Power Corporation (Napocor) barge destroyed by the storm surge. Around 200,000 liters of bunker fuel spilled at the shoreline of Barangay Botongon, Estancia, according to the Philippine Coast Guard.

Findings from the field validation survey of the Project NOAH Storm Surge Hazard Mapping Team revealed that the municipality of Carles (population 62,690), located in the northernmost part of Iloilo, was also inundated by up to five meters of storm surge.

San Francisco, Cebu

San Francisco is a small municipality in the province of Cebu, located on the Camotes Group of Islands. Located around 30 kilometers east of the main Cebu island, it has a population of a little over 47,000. The town has had a digital and manual rain gauge since 2009. Once rainfall amount goes above normal levels, the Local Disaster Risk Reduction and Management Office (LDRRMO) warns the purok leaders.

This purok system, along with the pro-active kind of local leadership and the use of real time weather information, is what enabled San Francisco to have zero casualties during the extremely devastating Typhoon Yolanda. A purok, though not a Local Government Unit, is a geographical subdivision of a barangay of about twenty to fifty households. These small clusters have a purok president that is part of the barangay council, who leads the community and leads his set of officers to perform more specified and targeted government functions, such as during disasters.

For example, San Francisco’s puroks hold typhoon drills before the anniversaries of two major storms that hit the town, i.e., Typhoon Bising in March 1982 and Typhoon Ruping in November 1991. San Francisco is officially recognized as a role model by the UN Office for Disaster Risk Reduction (UNISDR) in a highly hazard-prone part of the world, having been awarded the Sasakawa Award for Disaster Reduction in 2011.

LDRRM officers diligently monitored Typhoon Yolanda a week before it hit the Philippines, through monitoring its sensors and observing PAGASA data. In the islet of Tulang Diyot, purok officers started evacuating their communities by November 6, two days before landfall, and had evacuated around all roughly 1000 residents by November 7. The island was utterly destroyed by the Yolanda-induced storm surges, all houses were wiped out, but San Francisco had zero casualties due to the prompt actions of its local leaders and community members.

Map of Cebu, with Camotes Island. From: suroypilipinas.org

Map of Cebu, with Camotes Island. From: suroypilipinas.org

ELR. (2013). 150k liters of bunker fuel from Yolanda-damaged barge spills off Iloilo coastline. GMAnetwork.com.

Lagmay, A.M.F., Norman Kerle. Typhoons: Storm-surge models helped for Hagupit. Nature, Vol. 519, 414. doi:10.1038/519414b

Lagmay, A. (2014). Devastating Storm Surges of Typhoon Haiyan. International Journal of Disaster Risk Reduction. 10/2014; 11. DOI:10.1016/j.ijdrr.2014.10.006

McElroy, A. (2013). Evacuation saves whole island from Typhoon Haiyan. UNISDR.org.

NDRRMC. (2013). NDRRMC, Sitrep no. 107 effects of typhoon yolanda (haiyan). National Disaster and Risk Reduction and Management Council. Online.

National Statistics Office. (2010). Census of population and housing. Online.

Ranada, P. (2014). San Francisco: The island where all survived. Rappler.com.

UNISDR. (2011). UN Sasakawa Award 2011. UNISDR.org.

Yabes, C. (2013.) At the Tacloban astrodome, refugees find a home in ruined bars. GMA News Online.

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