Mapping Philippine Vulnerability to Environmental Disasters

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Conclusions and Recommendations
Objectives Map Themes
The Atlas Scope and Limitations
Methodology and Framework Results
Basemap Dissemination Activities
Spatial Database

By its location in the tropics, the Philippines is found to be naturally prone to environmental disasters. This situation plus other human and developmental factors contribute to communities' inability to cope with such disasters.

There are complex factors at play, which are climate/weather-related, geophysical, ecological and anthropogenic. Identifying vulnerability and risk according to the above categories assists in completing scenarios, whether historical and/or projected, and enables communities to cope with and adapt to environmental disasters.


The aim of this project, Mapping Philippine Vulnerability to Environmental Disasters, is to identify areas in the country that are at high vulnerability and risk to environmental disasters. Environmental disasters refer to the collective impacts of damaging events on our surroundings. Hazards and disasters are mapped and analyzed via geographic information systems (GIS), environmental modeling tools and resulting spatial databases.

The maps, when properly disseminated, form important policy and decision tools towards better disaster management and adaptation in the country. It is recommended that composite vulnerability and risk indices using the GIS approach be further developed, that is, by and across categories of factors. This is aimed at improving national and local assessment. Results may then guide and strengthen capacity building in disaster preparedness and management.


The Atlas or collection of associated maps and analytical results are for dissemination to the public and concerned agencies who are responsible for disaster management and environmental stewardship in the country.


Recent and major events, as well as their cumulative impacts, highlight the importance of identifying the vulnerability levels of certain areas and segments of the Philippine population to collective hazards forming disasters. Vulnerability is defined as the susceptibility to stresses or hazards, and the capacity (or lack thereof) to prepare, cope and recover from such hazards. Human vulnerability, in particular, is a condition resulting from physical, social, economic and environmental factors, which determine the likelihood and scale of damage from the impact of a given hazard. Human vulnerability includes the vulnerability of social and economic systems, health status, physical infrastructure and environmental assets.

Vulnerability is the concept that explains why a community is more or less at risk to a given hazard. However, neither vulnerability alone nor hazard alone determines the occurrence of a disaster. A hazard, by itself, is simply a potentially damaging event or physical disturbance. It is in the coming together of hazard and vulnerability that disaster occurs. In recognition of these different factors at play, the analytical framework for assessing risks to disasters, which is adapted from the UNDP model and previously cited, is as follows:

Risk = Hazard x Exposure x Vulnerability

Risk as it is used here refers to the likelihood of disaster, loss or harm. It is a function of hazard frequency or severity, the exposed element or element at risk, and the vulnerability of that element. In the case that several hazards are under consideration, a composite measure of risk can be attained by summing the risks to specific hazards as follows:

Rtotal = R1 + R2 + R3 + ... + Rn

This framework provides us with a simple method for determining risk based on existing hazards, exposure levels and conditions of vulnerabilities. Risk assessment is both important and urgent in that development scenarios and choices influence the distribution and magnitude of disaster risk. Thus, adaptation as well as disaster prevention and mitigation must be integrated into development strategies and plans by decreasing vulnerability levels, or avoiding the impacts of hazards when possible.


For our base map, the NAMRIA dataset is chosen, which is provincialized and is also used by the Philippine Biodiversity Priorities. The Spratleys are not included in this standard map.


Geographic Information Systems or GIS are used to generate maps composing the Atlas. GIS are defined as the body of automated mapping tools that permit spatio-temporal and statistical analyses. The major components of GIS include spatial databases that revolve around spatial units. These spatial databases are linked to corresponding maps and map layers of common geographic coordinates and projection.

In our case, the spatial units concern and are defined by national, regional and provincial boundaries. The spatial database revolving around provinces as spatial units is of the relational type, meaning in the form of spreadsheets. Spatial information are of the raster and vector forms depending on available data. Other components of the GIS are data input and output subsystems as well as the data processing, management and query subsystems.


As mentioned, the categories of map themes used to establish and form the GIS-generated Atlas are:

  • Climate/ Weather-Related
  • Geophysical
  • Ecological
  • Anthropogenic or Human and Developmental

The boundaries between these categories are not strict nor exclusive. Categories interrelate as well.

The use of mapping techniques to provide a spatial perspective assists in spatial analyses. The ultimate goal is the facility towards the formulation of more effective ways to respond to risks in terms of policy and decision-making and strategizing adaptation. Because of the complexity of factors at play, hazards are first categorized and mapped individually. Then, these datasets are merged by multiplication with exposure and vulnerability levels to obtain risk. The risk maps are related with other themes and aggregated by category.

Vulnerability and risk mapping in this project is undertaken at the national scale but the approach may be adapted for local-scale mapping as well.

A shortlist of the numerous factors considered by this project, classified by type is as follows:

  1. Hazards
    1. Natural
      1. Typhoon
      2. Drought (El Niño)
      3. Earthquake (Tremor, Landslide)
      4. Volcanic eruption
      5. Tsunami
    2. Anthropogenic
      1. Deforestation
      2. Mining (Except coal)
      3. Climate change (temperature, rainfall)
  2. Exposure
    1. Population
    2. Natural habitats
    3. Terrestrial and marine conservation areas
    4. Groundwater
  3. Vulnerability
    1. Human Development Index (encompasses Education, Health and Economy)
    2. Poverty indices
    3. Urban centers by hierarchy
    4. Socio-economic pressures
    5. Transport

The list of maps composing the Atlas is available in Appendix A.


The above categories or sets of maps guide the application of GIS in vulnerability and risk mapping. All the maps composing the Atlas are provided in Appendix B as thumbnails.

In mapping, it is important to note that we have not addressed national-scale flooding or proness to floods. This is a topic for future research.

Geographical Information Systems (GIS) is the body of tools for thematic mapping and spatial analyses. In terms of the latter, we refer to spatio-temporal and statistical analyses.

GIS may be applied graphically in the form of grid or raster and/ or linear or vector-based mapping. In this study, we combined both forms of information whenever data permits.

Specifically, the GIS approach can be utilized for the following tasks:

  • Base mapping with and/ or around administrative units,
  • Grouping of map themes by categories and sub-categories,
  • Breakdown of legends into variables and their corresponding characteristics or attributes,
  • Overlaying and/ or correlation of themes of different types and forms,
  • Change detection or multitemporal studies for monitoring conditions.

In addition to the maps produced by GIS software, comparative matrices can also be generated. These matrices complement the maps by way of:

  • Spatial databases, based on which logical and/ or numerical operations are performed,
  • Comparison across spatial units, for example nations, regions, sub-regions, provinces, cities/ municipalities as well as barangays
  • Comparison across different themes by category of hazards and disasters,
  • Merging of qualitative with quantitative assessments.

Based on spatial analyses, it is clear that we have to dovetail political or administrative interventions with ecological concerns, that is, down to the district or barangay levels. National-scale vulnerability and risk maps, nonetheless, point to where hotspots are likely to occur as well as their possible forms. Disaster preparedness strategies and plans may, thus, be pursued on the initiative of the concerned sectoral representatives as well as stakeholders within localities. These should at best influence Comprehensive and Sustainable Land Use Plans (CSLUP) and Strategies of Local Government Units (LGUs).

It is recommended that apart from the Calamity Funds, financial resources be allocated for adaptation and mitigation as well, meaning disaster preparedness. Corollary to this, the goals of adaptation policies and strategies are:

  • To proactively/ responsively bring adaptation strategies closer to realities on the ground
  • To make strategies part of sustainable and comprehensive land use/ land cover planning and management
  • To make adaptation strategies the responsibility of all sectors influencing development
  • To locate political interventions and reconcile them with ecological concerns

The objectives of the Dissemination Workshop are as follows:

  • To disseminate findings of the project
  • To obtain feedback on the usefulness of results
  • To find out how best to inform the public about project results
  • To explore follow-up activities arising from results and feedback on them

Associated presentations are available in Appendix C.


The concept of vulnerability and risk to environmental disasters, coupled with its geographic or spatial perspective, gives us meaningful and useful insights. In particular, vulnerability and risk mapping assist in spatial analyses towards the formulation of more effective ways to respond in terms of policy and decision-making as well as strategizing adaptation and mitigation at various scales.

The risk maps, in general, aid in identifying areas where further study is both important and urgent. Strengthening of the framework, R = H*E*V, is needed to more accurately portray actual risk conditions. Techniques may include considering collateral hazards, varied exposed elements, and multiple vulnerability indicators, that is, depending on the available data.

Moreover, national-scale mapping reveals trends and themes across categories that may potentially be correlated. Future directions, therefore, can also include comprehensive studies to establish if such correlations do exist, and how these connections influence vulnerability and risk assessment.

Given the findings across categories, it is recommended that the next phase of risk mapping include the following activities:

  1. Review and reformulate framework for determining risk (R = H*E*V) and consider:
    1. possible collateral hazards,
    2. livelihood as well as lives exposed,
    3. multiple vulnerabilities, and
    4. efforts at adaptation, prevention and mitigation that may reduce risk
  2. Determine the effect of the presence of urban centers, and quantify access to urban centers using maps of location, slope and transportation;
  3. Create ecological disaster risk maps;
  4. Establish correlations among the anthropogenic, ecological and disaster risk maps; and
  5. Conduct localized disaster risk mapping in high-priority areas.
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