Evaluating Regional Flood Disaster Resilience Based on the DROP Model and TOPSIS Method: A Case Study of the Katsushika Ward, Tokyo

Abstract

Tokyo is on one hand becoming increasingly vulnerable to flood disasters due to flooding of greater severity and frequency. Tokyo’s vulnerability to flood disasters has increased because of the changes in population structure, outdated infrastructures, an insufficient energy supply, the deterioration of flood control facilities, high-value economic assets, and the weakening of flood control awareness. Therefore, the study of key factors related to flood disaster resilience is important to enhance the flood resilience of the city. This study aims to conduct a systematic analysis of flood resilience regarding ecology, economics, societal effect, infrastructure, and community capacity based on the disaster resilience of place (DROP) model. An indicator system was developed incorporating 20 indicators. The resilience of Katsushika Ward to flood disasters was quantified using collected data, the coefficient of variation, technique for order preference by similarity to an ideal solution (TOPSIS) method, the DROP regional disaster resilience model, and a geographic information system. The results showed that there are deviations in the resilience values of six dimensions, among which the system resilience and social resilience values are relatively weak. However, the highest resilience value lies in eco-environmental resilience and infrastructure, which is of great significance in disaster resilience assessment in terms of the disaster resilience dimension. In order to improve the resilience of the ecological environment, the Katsushika City’s local government needs to not only facilitate the local greening rate and air quality improvement but also properly handle sewage and garbage. It also has responsibility to strengthen the flood prevention capacity of medical facilities, refuge facilities, welfare facilities, and residential buildings so as to enhance infrastructure elasticity. From the distribution point of view, the regions with the strongest and weakest resilience to flood disasters are found in the northwest and southeast regions, respectively. Therefore, it is concluded that there is spatial variability in flood disaster resilience in the northwest, southwest, and east regions. This research could definitively help determine the spatial distribution of flood resistance in a certain area, thereby helping local governments improve their ability to respond to disasters and formulate appropriate plans to improve their resilience.