Estimation of Inundation Mitigation Potential Due to Time Variability in Japan

Climate change has led to an increase in precipitation and the number of rivers exceeding their flood levels in all regions of Japan. It is pointed out that the amount of precipitation and the frequency of flooding will continue to increase in the future, and there is concern that the number of disasters that cannot be prevented simply by improving river channels will increase. In recent years, basin-based flood control measures have been promoted in Japan to reduce flood damage throughout the entire basin, and estimating the effect of water storage outside the river channel can help in the planning of basin-based flood control measures. In this study, data on off-channel water storage capacity for paddy fields, parks, and school reservoirs were collected on a national scale, and their functions were evaluated. In Fukushima Prefecture, the contribution of internal and external water storage was determined in consideration of future population changes, and priority areas were selected for countermeasures.