Analysis of Optimal Evacuation Routes Considering Flooded Roads in the Event of the Namgang Dam Collapse

With the increasing frequency of extreme flood events due to climate change, the area from the Sinan-dong Administrative Welfare Center to the Ihyeon-dong Administrative Welfare Center in Jinju City was designated as a Special Risk Zone under the hypothetical failure of the Namgang Dam. In this study, flood risk and evacuation feasibility were evaluated. To achieve this, two-dimensional hydraulic simulation results from the Hydrologic Engineering Center's River Analysis System were integrated with GIS-based network analysis. By linking hydraulic modeling with spatial analysis, this approach overcomes the limitations of conventional evacuation models based on static road networks and establishes a dynamic evacuation routing system that reflects road inundation conditions. The results show that the Special Risk Zone, located in a low-lying area near the Namgang River, faces extremely high flood risk, with flood arrival times of approximately 5-57 min and a maximum inundation depth of approximately 15 m. Areas classified as Extreme and Very High risk account for approximately 46.5% of the zone, indicating that structural measures alone are insufficient. Most major roads become inundated, significantly restricting pedestrian evacuation, whereas the combined inundation depth and flow velocity increase the risk of pedestrian instability. Based on these findings, vertical evacuation to the upper floors or rooftops of nearby buildings is identified as the most practical short-term strategy, whereas detour-based horizontal evacuation using higher elevation areas is proposed to improve evacuation feasibility and support disaster management in downstream urban areas.