2025 Volume 81 Issue 16 Article ID: 24-16043
In the Ichinomiya River basin in Chiba Prefecture, a wide range of flooding occurred due to typhoon Yun-yeung on September 8, 2023. To assess the effectiveness of ongoing flood control measures, we examined the situations of the river flow and the inundation based on the observed data and did the numerical simulation with and without the flood control measures. By comparing the observed data, the rainfall amount in 2023(R5) is higher than one in 2019(R1), but the river water level and the inundation volume of R5 flood are less than those of R1 flood. The simulated results showed that the flood measures are effective in reducing flood damage in R5 flood. These results quantitatively demonstrate the effectiveness of recent flood control efforts in mitigating the R5 flood's impact to the R1 flood.
