## 3 Results
### Emergency Flood Evacuation Path Planning Analysis  
From an emergency response perspective, and considering the dynamic evolution of floodwaters following a dam breach, emergency evacuation path planning is conducted using the Dijkstra algorithm. The objectives are to minimize evacuation time and reduce risks to evacuees. In the worst-case scenario simulation, it is assumed that evacuation begins immediately after the breach occurs. The walking speed of evacuees, assuming they are not hindered by floodwaters, is set at 1.6 m/s [31; 32]. Emergency evacuation path planning is then carried out based on the coupled flood-road network model for four time intervals: 10, 20, 30, and 50 min post-breach. The planning results are overlaid on topographic maps, as shown in Figure 8, which illustrate the available road networks and evacuation routes for each time period. Figure 8: Flood avoidance path planning results: (**a**) 10 min after dam failure; (**b**) 20 min after dam failure; (**c**) 30 min after dam failure; (**d**) 50 min after dam failure. Ten minutes after the dam breach, as shown in Figure 8a, the floodwaters have not yet reached the 192 Township Road Bridge, and the downstream road network remains largely unaffected, with most roads still passable. Following the proximity principle, evacuees from the affected points should proceed swiftly toward the nearest shelter points. Twenty minutes after the breach, as shown in Figure 8b, the floodwaters have submerged the 192 Township Road Bridge, rendering Path 1 inoperable. Evacuees at Affected Point 1 who have not yet moved can no longer reach Shelter Point B and must instead take Path 2 to reach Shelter Point A. Thirty minutes after the breach, as shown in Figure 8c, water depths exceeding 0.8 m at Shixia Bridge, Gangzai Bridge, and Bosi Bridge near the T-shaped river junction cause Paths 6 and 11 to fail. Evacuees at Affected Points 5 and 8 can no longer move toward Shelter Point E. Those at Affected Point 5 can take Path 7 to reach Shelter Point A, while evacuees at Affected Point 8 can use Path 12 to reach Shelter Point D. Fifty minutes after the breach, as shown in Figure 8d, most village roads near the riverbank are submerged with water depths exceeding 0.8 m, causing Paths 7 and 12 to become impassable. Evacuees at Affected Point 5 can still reach Shelter Point A via Path 8, and those at Affected Point 8 can continue to Shelter Point D via Path 13. In total, 13 emergency evacuation paths are identified, with details on path lengths and evacuation times provided in Table 3.  
The evacuation plans for the four time intervals are presented in Table 4. The transfer paths are dynamically adjusted based on road network failures to mitigate the impact of flooding on the evacuation process, thereby ensuring the safety of evacuees. By comparing the safe transfer time for each disaster point with the required time to traverse each emergency evacuation path, it is concluded that all disaster victims at the eight affected points can successfully reach their designated shelter points within the safety time window, without any incidents of blockages caused by path failures due to flooding. This dynamic adjustment strategy enhances the reliability of the emergency evacuation path planning, ensuring a high level of safety for evacuees at various stages of flood evolution. As a result, the strategy effectively reduces the risk of flood-related disasters during the evacuation process.