Developing a risk assessment model for rainfall-induced flood hazard-case study on flood-prone areas of Taichung city

Several typhoon floods recently has struck Taiwan and caused serious damage, the importance of flood mitigation and flood risk assessment have, thus, been recognized. Flood risk assessment consists of three factors: hazard, vulnerability, and exposure. The analysis of hazard in this study was implemented by using the physiographic drainage-inundation model to simulate flooding area and depth under various rainfall scenarios. The exposure refers tothe population distribution in this study. As for the vulnerability, the concept of fragility curve originated from the field of earthquake disaster analysis was employed to develop the flood fragility curve. A vulnerability analysis was accomplished by combining the flood fragility curve and flood disaster losses scenario. This study developed a flood risk assessment model and drew the flood risk map under various rainfall scenarios. The areas with high flood risk are coastal areas and riverside metropolitan area in Taichung City. Public transportation under flood disaster risk is also assessed and discussed.