A Route Search System to Avoid the Danger to Life in Dynamic Inundation

In recent years, the frequency of torrential rains has increased due to abnormal weather conditions. Torrential rains have caused extensive flooding damage in many areas. As delays in evacuation can pose a threat to life, a quick search for safe evacuation routes has become more important than ever before. In this study, we constructed a new system for searching evacuation routes that incorporates a function that varies the weight of each road in the route search depending on the distance from the flooded area D and the distance that the flood area extends in 10 min D′ (i.e., the flood’s inundation speed). We conducted multiple hypothetical flood simulations with different locations of levee breaches and shelters in the study site (Obihiro City, Japan). Then, we compared the results with the conventional system that does not include the proposed function. The results showed that the system proposed in this study increased the number of successful evacuees by up to 2.16 times compared to the conventional system. In our system, the weight function is set to the Cd power of D/D′; increasing the model parameter Cd selects a route that detours more of the flooded area. The model parameter Cd that maximizes the number of successful evacuees is roughly constant, regardless of the locations of the levee breaches or shelters in the study site.