Flood Risk Assessment at the Administrative District Level Based on SSP Scenarios

Owing to climate change, annual rainfall and the likelihood of extreme precipitation events are projected to increase in the future (2021-2100), raising concerns about the intensification of flood damage. This study assessed flood risk at the administrative district level using three key components—Hazard, Exposure, and Vulnerability—and 13 detailed indicators that reflect meteorological factors, historical flood records, population data, and regional characteristics. In particular, future changes in flood risk under climate change were quantitatively evaluated using the SSP scenarios. The results showed that regions with the top 10% of flood risk scores exhibited high consistency with flood-prone areas identified on existing flood inundation maps. Under current conditions, approximately 25% of the administrative regions are classified as high- or extremely-high flood-risk areas; however, under future conditions, this proportion increases to as much as 42%, depending on the SSP scenario. In addition, the maximum flood risk value increased by approximately 1.7 times compared to current conditions, with scenario-dependent increases ranging from 1.12 to 2.19 times. The flood risk assessment results and high-risk area classifications presented in this study can serve as foundational data for more detailed flood risk analyses and are expected to provide practical evidence for establishing flood risk management policies and prioritizing investments in flood control infrastructure at both the national and local government levels.