The Importance of Hazard Maps in Averting Disasters

By Alfredo Mahar Lagmay

This article was originally published in the Manila Bulletin on February 29, 2016.

Hazards are forever a threat but can be managed if we learn the lessons from past disasters. Over the years, it has become clear that effective disaster prevention and mitigation entails two important aspects.  The first is the delivery of accurate, readily accessible, understandable and timely warnings.  It is the responsibility of government and should be executed using the best science and advanced tools. The second entails the appropriate response of people when they are given a warning. This is the more difficult part because it requires the long-term involvement of everyone and not when it’s too late -people must educate themselves on the different hazards, know the dangers in their neighborhood and practice evacuation drills. These long-term preparations need to be accompanied by reliable hazard maps that depict scenarios of hazards in a community. It is imperative that the maps be accurate because all plans, even if well executed, will fail if they are wrong.

Inaccurate maps may have cost the lives of thousands Filipinos in the past.  Take for example the 2012 Barangay Andap disaster in New Bataan, Compostela Valley where 566 people heeded warnings by seeking refuge in an evacuation center.  Instead of being relocated to a safe shelter, the evacuation center became their grave when debris flows overwhelmed the site. Another example is the Yolanda disaster. Notwithstanding the shortcomings of the storm surge warnings, there were people who dutifully trooped to evacuation centers in Tacloban where they met their untimely death. Seventy percent of evacuation centers in Tacloban were inundated by storm surges, which only tells us that the storm surge hazard maps were erroneous if they were used in the city’s disaster mitigation plan.  Otherwise, the evacuation centers would not have been located in those places.

To rectify the problem, the Department of Science and Technology embarked on a program on 6 July 2012 called the Nationwide Operational Assessment of Hazards (NOAH).  Using frontier science and advanced technology, we are now able to map out the Philippine landscape at very high resolution. From maps that depicted the land with vertical accuracy of ± 6-7 meters and horizontal resolution of 30 meters, we now have maps that have a vertical accuracy up to ±15 centimeters and horizontal resolution of 1 meter. This is the initial stage to create detailed maps that show hazards at barangay level. Armed with the knowledge on the physics of how water flows and stability of mountains, we can now use powerful computers to simulate floods and landslides to identify hazardous areas. More importantly, we are also able to identify safe areas, which are the suitable sites for evacuation centers and future development of areas not prone to natural hazards. Previous maps, which are still the official maps used today, except in the 171 municipalities in the Yolanda corridor, have hazards shown everywhere in the map. Such hazard maps make it difficult to assess an area to build a well-planned and resilient community against disasters.

DOST-Project NOAH has completed the detailed hazard maps for landslides and storm surges. Flood hazard maps, however, are still incomplete because they are more difficult to generate. Hopefully, they will be finished soon.  All maps are available in the DOST-Project NOAH website at and in an award-winning mobile app called Arko.  The NOAH maps are distributed to empower local government units (LGUs) and individuals.  By knowing the hazards in their neighborhood, people are made aware of the dangers in their community – the first step in effective disaster preparedness and mitigation. In the Philippine context, however, the availability of these online maps is inadequate because not every Filipino has access to the Internet. Atlases or the hardcopy version of the digital hazard maps are needed by each barangay. Schools need them as well because it is an excellent place to develop skills in map reading. The landslide and storm surge hazard atlases have already been prepared for every province and are waiting to be printed.  The sooner there is a budget for their printing and distribution; the earlier communities can strategize their actions. Without the hazard maps, no amount of warning will suffice in efforts to avert disasters. Warnings need to be matched with the appropriate response, which only happens when there is a reliable map to map a good plan.

hazard map atlas

One Comment:

  1. I am interested in the vertical accuracy and the horizontal resolution of the data used in your NOAH Project. Could you tell me the how this data was created? It is extremely impressive how your project has developed and I look forward to seeing the future developments in your contingency operations.

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