Mapping Philippine Vulnerability to Environmental Disasters

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National-scale mapping does not only serve to point out priority areas, but it also aids in the identification of trends and themes across map categories that can be potentially correlated. Comparative spatial analyses of maps yield commonalities and patterns that illuminate directions for further study.

1. COMBINED DISASTER RISK MAPS
a. Climate- and Weather-Related Maps
Risk to Projected Temperature Increase Risk to Projected Rainfall Change Risk to Typhoons Risk to El Niño Combined Risk to Climate Disasters

Among the climate- and weather-related risk maps, the Risk to Typhoons map and the Risk to Projected Rainfall Change map have areas of Central Luzon and the Bicol region in common as high to very high risk areas. On the other hand, the area that ranks high to very high in risk in both the Risk to El Niño and Risk to Projected Temperature Increase maps is Western Mindanao.

The Combined Risk to Climate Disasters map represents the sum of the normalized, provincialized risks to typhoon (super typhoons, typhoons, tropical storms and tropical depressions), drought caused by El Niño, projected rainfall change and projected temperature increase. The top ten provinces are: Albay, Pampanga, Ifugao, Sorsogon, Biliran, Rizal, Northern Samar, Cavite, Masbate, and Laguna. In general, Central Luzon and the Bicol regions rank high to very-high on the risk scale. This indicates that it is the risk to typhoon scores and risk to projected rainfall change scores that dominate the summation of risks. In the case of the risk to El Niño scores and risk to projected temperature increase scores, the gap in the scores is between the highly-ranked provinces and the rest of the country as not as great as with the other two maps.

b. Geophysical Maps
Risk to Earthquakes Risk to Earthquake-Induced Shallow Landslides Risk to Volcanic Eruptions Risk to Tsunamis Combined Risk to Geophysical Disasters

The maps of areas at risk to earthquakes and earthquake-induced landslides have certain areas of Central to Northern Luzon and Eastern Mindanao in common. However, there are areas like Bukidnon and Lanao that have a high risk to landslides but a low risk to earthquakes, indicating that there must be other factors contributing to the occurrence of landslides in these areas. Areas at risk to both tsunamis and volcanic eruptions include the northwest to southeast diagonal across RP. Given this similarity, the identification of factors that can correlate volcanic eruptions and tsunamis can be subjected to further study.

The Geophysical Disaster Risk Map represents the sum of the normalized, provincialized risks to earthquakes, earthquake-induced shallow landslides, tsunamis and volcanoes. The top ten provinces include: Sulu, Camiguin, Ifugao, Davao Oriental, Sarangani, Benguet, Surigao del Sur, La Union, Lanao del Sur, and Zambales. In general, Central Luzon and Eastern Mindanao are the high-ranking areas.

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2. ANTHROPOGENIC MAPS IN CONJUNCTION WITH DISASTER RISK MAPS
Land Use Classification Gross Value Added in Agriculture, Fisheries and Forestry by Region (1999) Gross Value Added in Industry by Region (1999) Gross Value Added in Services by Region (1999) Heirarchy of Urban Centers (1980) Heirarchy of Urban Centers (2000)
a. Land Use Map

i. Versus Climate Risk Map: areas in central Luzon, Bicol Region and Sulu islands that rank very high on the combined risk to climate disasters map are primarily agricultural areas and coconut plantations. Thus, climate disasters pose a risk not only to lives but also to livelihood. There is a need to measure the risk of climate disasters to livelihood.

ii. Versus Geophysical Risk Maps: very high risk areas in central Luzon and eastern Mindanao are plantations and dipterocarp forests, which also serve as a source of livelihood. Together with the slope map, it may be advisable to further study the effect geophysical disturbances on livelihood in these regions.

b. Gross Value Added and Disaster Risk

The GVA maps represent an alternative method for quantifying the effect of disasters on livelihood. Comparative analysis shows that areas at low risk to disasters like Palawan are also those with high GVA. These maps can further be correlated with maps of ecological resources to ascertain of these areas rank high on the GVA solely due to the low occurrence of disasters or due a combination of factors such as low occurrence of disasters coupled with available ecological resources.

c. Heirarchy of Urban Centers Map

i. Versus Climate Risk Map: Provinces with the highest risk in central Luzon are also those with the most urban centers. Assuming that most resources, telecommunication and transportation facilities are concentrated in urban centers, the vulnerability of these regions can be reduced (hence, reducing risk). In future risk maps, there is a need to factor in (1) the capability of each urban center to respond to disasters, and (2) the surrounding provinces' access to urban centers quantified by location, slope, roads, transportation and communication.

ii. Versus Geophysical Risk Map: The effect of having urban centers within high-risk areas is a double-sided issue. On the one hand, urban centers can better respond to, for instance, medical needs in a time of disaster. On the other hand, if the disaster in question is an earthquake or a landslide, then the presence of many infrastructures within an urban center may actually compound the hazard. Collapsing buildings, ground liquefaction and the like are the collateral hazards of having an earthquake in an urban center. Since the available resources and infrastructures differ from one urban center to another, it is advisable to carry out future risk analysis on a local scale.

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3. ECOLOGICAL MAPS IN CONJUNCTION WITH DISASTER RISK MAPS
Integrated Marine and Terrestrial Priorities Groundwater availability Slope and Forest Cover Mines and Protected Areas ()
a. Integrated Marine and Terrestrial Priorities Map

Temperature and precipitation are said to be two major indicators of climate. Certain areas highly at risk to projected temperature increase and rainfall change are also rank highly on the map of marine and terrestrial priorities. It becomes relevant, therefore, to determine how the projected climate change may potentially affect the country's ecosystems, particularly in areas of high marine and terrestrial priority. These maps can further be correlated to the map of socio-economic pressures to determine in which areas the effects of climate change may be potentially aggravated. Factors like changes in population and land use may affect the priority rankings of marine and terrestrial resources.

b. Groundwater Availability

Comparing the map of groundwater availability to the map of risk to El Niño shows that areas in Mindanao which are most at risk to induced drought actually possess productive aquifers that can possibly mitigate the effects of El Niño.

c. Slope and Forest Cover

This map can be correlated to the map of landslides in the sense that areas with steeper slopes are expected to be more at risk to landslides. It has been hypothesized that the presence of forest systems, although beneficial in preventing excess runoff and flash floods during a typhoon, may actually contribute to the occurrence of landslides due to the sheer weight of the vegetation.

d. Mapping Ecological Disaster Risks

Mining activities have historically been known to contribute towards water pollution. The map of mines shows that several mining activities are located near major river basins or within critical watersheds. The R=HEV framework can be used to map the risk of water contamination due to mining activities and other such ecological disasters. It must be noted however, the occurrence of ecological disasters may be closely correlated the geophysical and climate and weather-related disasters which may act as triggering mechanisms.

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