[A-AS01] From Weather Predictability to Controllability

[AAS01-P06] Efficiency Assessment of Rainfall Suppression on Flood Inundation Mitigation

*CHANG JUICHE¹, KAZUAKI YOROZU¹ (1.Disaster Prevention Research Institute, Kyoto University)

Keywords:Heavy rainfall suppression, Inundation simulation, Water-related disasters

Flood inundation is one of the most impactful natural disasters due to its widespread and long-term characteristics, affecting human beings. Under the impact of climate change, heavy rainfall events have been proven to become more intense and frequent, increasing the risk of flooding disasters for local residents. In Japan, well-known inundation disasters caused by heavy rainfall events are usually triggered by typhoons or stationary fronts. However, short-term extreme rainfall also poses a threat to Japanese society due to its rapid formation and high intensity, making it difficult for people to prepare in advance. Traditional prevention measures involve using dykes and retention systems, as well as enhancing the drainage system by constructing pipes and installing pumps to remove water from populated areas. However, constructing such infrastructure may take time to design and can be costly to build. This may not be effective in protecting people in the short term. Additionally, the economic benefits may not align with the priorities of the local government. Weather modification is a novel idea for controlling rainfall by changing the formation of cloud systems. The seeding method of weather modification is used to create rainfall in dry areas by condensing water vapor in the air through the release of particles. In this study, rather than explaining the method to modify the weather, we are going to illustrate the impact of flooding using the rainfall control method. Applying the rainfall-runoff model 1K-DHM, the changes in river discharge due to rainfall control can be recreated for discussion. The rainfall modification scenarios use the output from the climate model, which simulates the seeding method. The simulated river discharge is applied to the inundation model as the later river flow in the 1D and 2D Inundation Model Coupled with the Rainfall-Runoff 1K-DHM (IMCR) to simulate the inundation area and its depth. Based on the results, we conclude the relationship between rainfall control and inundation changes to evaluate the efficiency and benefits of using rainfall control to mitigate flooding risks to humans. Additionally, we demonstrate the applicability of the rainfall control method to protect society with a more flexible strategy.