FLOOD MITIGATION EFFECTS AND SEDIMENTATION FUNCTION OF CANDABA SWAMP WITHIN PAMPANGA RIVER BASIN IN THE REPUBLIC OF THE PHILIPPINES

摘要

Flood control project on the Pampanga River Basin in the Republic of the Philippines, conducted from 1939 to 1975 following a suggestion from U.S. Army Corps of Engineers, has a unique characteristic. That being an embankment constructed only on the right bank of the river to protect lives and properties in the right basin area, and the Candaba Swamp located on the left basin area was regarded as flood retarding area. The wetland comprises 486 square kilometers with a reserve storage capacity of approximately 2 billion cubic meters. However, previously the flood mitigation effects of the Candaba Swamp have not been examined thoroughly. In this paper, the flood mitigation effects of the wetland were studied by hydrologic analyses under two conditions, 1) with and 2) without the wetland Annual sedimentation in the wetland was estimated by discharge data and empirical sediment transport equations. The results quantitatively show the significant flood mitigation effects and sedimentation function of the Candaba Swamp within the Pampanga River Basin.