philippine vulnerability to environmental disasters

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IV. Site AnalysisA. Philippines General Climate and Vulnerability to Disasters

The Philippines' exposure to disasters is to a significant extent due to the country's geographical and physical characteristics (CDRC, 1992). It is the worlds largest archipelago composed of more than 7,100 islands. It lies along the Western Pacific Basin, the worlds busiest typhoon belt, with the average of 20 typhoons hitting the country each year. The country is further part of the Circum-Pacific seismic belt and lies in between two major tectonic plates, whose movements create mountain ranges, islands, volcanoes, earthquakes and tsunamis. El Nio occurrences induce drought in many parts of the Philippines, regularly posing a serious problem in agricultural production and potable water supply.Climate- and weather-related hazards, in particular, refer to the direct and indirect effects of observed changes and/or projected deviations from present-day conditions of natural climate events (such as increases and decreases in precipitation and temperature); and impacts of changes in the frequencies and occurrences of extreme weather/climate events (such as tropical cyclones, droughts, and El Nio and La Nia events).The termtyphoonis used to refer to all kinds of tropical cyclones, of which there are four kinds. These are tropical depressions (65 m/s). In general, typhoons are considered extreme weather events. Geophysical events are destructive phenomena. However, these are part of the normal functioning of our dynamic planet. These so called hazards are due to naturally occurring processes in the earth's interior.Four hazards are considered under this category: Earthquakes, earthquake-induced landslides, tsunamis and volcanic eruptions. A natural process that is hazardous is the movement of lithospheric plates (the solid crust and a few kilometers of the upper mantle), which causes the tectonic earthquakes. US Geological Survey defines the termearthquakeas "both sudden slip on a fault, and the resulting ground shaking and radiated seismic energy caused by the slip, or by volcanic or magmatic activity, or other sudden stress changes in the earth (i.e. event by manmade explosions)".Furthermore, the resulting ground motion due to an earthquake produces another natural hazard such as landslides and tsunamis. Landslide is the downslope movement of soil and/or rock. Tsunami is a sea wave of local or distant origin that results from large-scale seafloor displacements associated with large earthquakes, major submarine slides, or exploding volcanic islands. One other example of a hazard is the ascent of molten material called magma beneath the earth's surface, which results to eruptions of a volcano. A volcano is a vent at the Earth's surface through which magma (molten rock) and associated gases erupt, and also the cone built by effusive and explosive eruptions.

Comparing the map of groundwater availability to the map of risk to El Nio (shown in the next page), 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 Nio.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.

The top 20 provinces at risk to typhoons are:1. Cagayan2. Albay3. Ifugao4. Sorsogon5. Kalinga6. Ilocos Sur7. Ilocos Norte8. Camarines Norte9. Mountain Province10. Camarines Sur11. Northern Samar12. Catanduanes13. Apayao14. Pampanga15. La Union16. Nueva Ecija17. Pangasinan18. Masbate19. Tarlac20. Western Samar

The top 20 provinces at risk are:1. Albay2. Pampanga3. Ifugao4. Sorsogon5. Biliran6. Rizal7. Northern Samar8. Cavite9. Masbate10. Laguna11. Batangas12. Sulu13. Western Samar14. Nueva Ecija15. Tarlac16. Pangasinan17. Basilan18. Metro Manila19. Camarines Sur20. La Union

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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. In general, Central Luzon and Eastern Mindanao are the high-ranking areas.

B. Macroclimate AnalysisSanta Rosa, LagunaSanta Rosa's climate is classified as tropical and is relatively dry from November to April and wet during the rest of the year. This location is classified as Aw by Kppen and Geiger. The temperature here averages 27.1 C. The average annual rainfall is 1914 mm. (Graphs from http://en.climate-data.org/location/1968/) Precipitation is the lowest in February, with an average of 17 mm. Most of the precipitation here falls in August, averaging 322 mm.

At an average temperature of 29.0 C, May is the hottest month of the year. January is the coldest month, with temperatures averaging 25.5 C.

Between the driest and wettest months, the difference in precipitation is 305 mm. Throughout the year, temperatures vary by 3.5 C.

C. Microsite Analysis

Sun Rays Study of the Site (January 29, 2016). Source: http://www.sunearthtools.com/dp/tools/pos_sun.phpShadow Study of the Site (January 29, 2016). Source: http://www.sunearthtools.com/dp/tools/pos_sun.php

Proposed Site.

Sun Path Diagram (2016). Source: http://solardat.uoregon.edu/download/temp/31015058.pdf