INUNDATION SIMULATION OF THE SUNA RIVER AND EVALUATION OF BANK BREAK USING BREACH PREDICTION METHOD

Abstract

 Many levees of small and medium rivers breached due to heavy rain in July 2018 and typhoon No. 19 in October 2019, and eventually enormous inundation damage occurred. In order to strengthen the embankment and lead to early evacuation in small and medium rivers, it is necessary to improve the accuracy of flood inundation analysis and predict the weak points of the embankment in advance. Therefore, in this study, validity of the analysis was examined by a flood simulation when upstream discharge and downstream water level were not available with respect to the Suna river in Okayama city, which was severely inundated due to the bank break. Furthermore, a simple bank breach prediction method was used to evaluate the bank break risk, and the effect of the bank height data on the flood inundation analysis results was examined numerically. As a result of comparing the numerically obtained inundation depth and the observed data, it was shown that the inundation simulation can be performed accurately by the boundary condition setting method proposed in this study. It was clarified that the weak points of the embankment can be extracted by using a simple embankment breach prediction method.