Flood Risk Assessment of Highly Urbanized Cities (HUCs) of Metro Cebu Based on Hazard- Exposure-Vulnerability Model with FUCOM-GIS and Rough Sets

The rapid impacts of climate change call for urgent actions, such as a comprehensive flood risk assessment, to mitigate the increasing threat of flooding. In many tropical countries, like the Philippines, the most frequent disasters are caused by hydrometeorological events such as floods. This research study focuses on evaluating flood risk through the development of a Flood Risk Index and a Flood Risk Map (FRM), guided by the Hazard-Exposure-Vulnerability interpretation of risk. By incorporating the physical characteristics and frequency of flood hazards, the exposure of human populations and infrastructure, and their inherent vulnerabilities, the study aims to provide a detailed and actionable assessment of flood risk. The areas of interest in this study, Cebu City, Mandaue City, and Lapu-Lapu City, are the highly urbanized cities of Metro Cebu, which houses the critical economic and political infrastructures of the Province of Cebu. Flood risk indicators were identified for each dimension of risk, and the cities provided their performance score for each of the flood risk indicator as well as corresponding priority values. The composite flood risk index for Metro Cebu was generated using Rough-FUCOM method and Hamy Mean aggregator. On the other hand, the development of flood hazard maps was done using the values and weights of the spatial flood risk indicators. The spatial flood risk indicators were mapped into ArcGIS, reclassified into layers, and was then combined using a raster overlay function. The study found out that the highly urbanized cities of Metro Cebu have a moderate flood risk index. This means that Cebu City, Mandaue City, and Lapu-Lapu City have moderate susceptibility to flooding but considering the drastic changes to climate, the concerned LGUs should increase their efforts and efficiently allocate resources especially on constructing flood control structures on areas that are classified as high to very high-risk level, as indicated in the flood hazard maps.