Flood risk assessment of the naeseongcheon stream basin, Korea using the grid-based flood risk index

Study Region: Naeseongcheon Stream Basin, Korea Study focus: We conducted a flood risk assessment using grid data for each indicator and a flood risk map. Using a grid-based flood risk map, grid data for the nine indicators included in the Hazard, Exposure, and Vulnerability items from 2016 to 2020 were selected and indexed by scoring each quantile interval. The entropy weight and Euclidean distance were then applied to calculate the grid-based item indices and flood risk index. Finally, the Expected Annual Damage (EAD) ranking calculated using the Korean flood risk assessment model was compared with the flood risk assessment ranking using grid data for 17 sub-basins in the Naeseongcheon Stream Basin for 2018. New hydrological insights for the region: The analysis showed that the absolute error was improved by the application of the flood damage rate and selection of the grid cells including damage targets. When comparing the flood risk assessment ranking of each of the 17 sub-basins with the EAD ranking, the mean absolute error was 1.882, and the root mean square error was 3.009. This confirms that qualitative flood risk assessment using grid data and flood risk maps can provide as much basin-level risk analysis as quantitative flood risk assessment. Therefore, the method pre-sented in this study can be utilized as a useful decision-support tool for the government's basin-level disaster prevention projects.