Community Classification Based on Landform Distribution and Flood Hazard Characteristics in Candaba Municipality, Pampanga River Basin, Philippines

抄録

The Candaba Swamp, situated in the lower reaches of the Pampanga River on Luzon Island, is important for maintaining the local ecosystem and storing floodwaters. Analyses using an original land classification map and satellite images describing the situation of recent flood inundation show that severe flooding in the Candaba Swamp mainly results from concentrated flood flows from eastern tributary rivers and the Cabiao Floodway onto lower landform surfaces. Communities in Candaba municipality, which includes most of the swamp, are divided into four groups based on flood hazard characteristics identified from landform distributions and recent flood inundation conditions. In the most flood-prone group, located in the central swamp, the average floor height of living spaces above the ground is higher compared to the other groups. However, in two-story houses, the most common house type in the group, the flood inundation height reached an average of 1.8 ft above the floor level during the worst flood event in the past five years. These households also tend to have longer residency and show less intention to relocate, likely because flood inundation in the swamp brings both risks and certain benefits. Implementing flood countermeasures, including those that maximize the functions of the Candaba Swamp, should consider these flood hazard characteristics and local living practices.