Spatial Multi-criteria Analysis (SMCA) for Basin-wide Flood Risk Assessment as a Tool in Improving Spatial Planning and Urban Resilience Policy Making: A Case Study of Marikina River Basin, Metro Manila – Philippines

The Philippines is one of the most natural hazard prone countries in the world, especially for water-related disasters (floods and landslides) triggered by typhoon. This study is motivated by the extreme flooding incidence in Metro Manila and surrounding areas in September 2009 during the most devastating typhoon to hit the country named as Tropical Storm Ondoy. Highly urbanized cities of Metro Manila in the downstream of Marikina River Basin suffered the most and the degradation of the upper part of the basin in Rizal Province has been identified as one of the main causes of such massive flooding. The research employed spatially explicit methods of assessment by using spatial multi-criteria analysis (SMCA). At the first stage, analytical frameworks were developed for Basin-wide Flood and Landslide Risk Assessment that integrate Hazard, Exposure and Vulnerability components. Necessary steps were taken including geodatabase preparation, variables definition, standardization of parameters, weight assignment of indicators, and sensitivity analysis. At later stage, analysis was applied in Arc GIS 9.3 software environment to conduct risk mapping. Identified Very High Flood Risk Areas were also validated by Satellite Images.