2025 Volume 81 Issue 16 Article ID: 24-16003
There are concerns that flood disasters will become more frequent and larger due to climate change. In Japan, river basin flood management is being promoted by combining various countermeasures. In this study, two flood countermeasures were assumed for the Kakehashi River that flows through Komatsu City, Ishikawa, Japan, and their flood damage mitigation effects were evaluated under multiple scenarios. The targets of the evaluation were temporary flood prevention walls to control flooding in the event of a levee breach, and urban planning measures to encourage relocation from areas at high inundation risk to safer areas. Furthermore, future population decline is taken into account when estimating changes in urban structure due to urban planning measures. When temporally flood prevention wall and urban planning measures were implemented independently, the reduction rate in flood damage were 22.2% and 24.8%, respectively. The reduction rate in flood damage when both measures were implemented was 41.2%. Furthermore, when urban planning measures were designed taking into account changes in inundation distribution due to the installation of temporary flood prevention walls, the damage reduction rate increased to 49.0%. This result shows the importance of appropriately coordination of multiple flood control measures.
