COMPOUND FLOOD MODELING FOR SMALL AND MEDIUM-SIZED RIVERS USING AN INTEGRATED MODEL OF ATMOSPHERIC, OCEAN AND RIVER

Abstract

 To assess compound flood risks from first-class to small-sized rivers, it is essential to develop a model that can solve the entire process in a unified manner. However, there have been few studies due to discontinuities between ocean and hydrological models and technical issues (meteorological field and wave modeling). The present study developed an integrated atmosphere-ocean-river model (SuWAT-River) by constructing a system that automatically converts river discharges into water levels. The water level of the rivers of Toyogawa (first-class river) and Yagyu and Umeda (small and medium-sized rivers) due to Typhoon Trami (2018) was reproduced with the high accuracy by SuWAT-River. Results of sensitivity experiments revealed that the water level rise due to storm surges and flooding was 7.3 and 3.2 times higher in the Yagyu River and Umeda River than in the Toyogawa River, respectively. Furthermore, these small and medium-sized rivers are extremely risky because the storm surges and flood peaks are superimposed on the estuaries.