GIS-ASSISTED FLOOD HAZARD ASSESSMENT AND MAPPING IN SELECTED AREAS IN ZAMBALES
Keywords: flood, hazard, assessment, mapping, GIS, field validation
Abstract. The Philippines experiences an average of 20 cyclones per year which cause flooding in many parts of the country and Zambales is one of them. In August 2013, Typhoon Labuyo hit the province that affected most of its municipalities and placing the town of Masinloc under the state of calamity due to occurrence of flood. Likewise, in September 2018, Typhoon Ompong hit the province of Zambales and brought heavy rains and floods to the municipalities of Sta. Cruz, Candelaria, Masinloc, and Palauig. Hence, this study was conducted to generate flood hazard maps in the northern municipalities of Zambales: Sta. Cruz, Candelaria, Masinloc, and Palauig using Geographic Information System through raster calculator. Weights of the factors considered in generating flood hazard susceptibility map, namely, elevation, slope, soil type, land classification, and distance from the river, were drawn from ten (10) experts and undergone Analytical Hierarchy Process (AHP). Field validation was also conducted to test the accuracy of maps generated. Flood hazard susceptibility was categorized into four (4) namely high, moderate, low, and no susceptibility. Results showed 15% of the total land area of Sta. Cruz, 12% of Candelaria, 15% of Masinloc, and 19% of Palauig had high susceptibility to flooding. Barangays situated in these areas should be given priority in flood adaptation and mitigating programs.