EVALUATION OF FLOOD AND HUMAN DAMAGE IN THE OMIZO RIVER BASIN DURING THE KUMA RIVER HEAVY RAINFALL IN JULY 2020

Abstract

 In this study, a flood simulation was conducted and hearings were held with local residents to clarify the flooding situation in the city of Hitoyoshi and determine the factors that caused human damage, with a focus on the Omizo River basin, during the Kuma River heavy rainfall in July, 2020. Consequently, a maximum depth of 2.7 m and the maximum velocity of 2.4 m/s was obtained in certain areas around the Omizo River. In the Omizo River basin, it was confirmed that flooding from rivers flowing down the mountain valley and the roads constructed in the rice paddy field areas acted as cross levees against flooding, which has not been reported before. In addition, the results of the estimation of the flooding conditions during heavy rainfall in the affected areas of the five victims around the Omizo River indicated that flooding occurred from three direction: "Kuma River in the south, Omizo River in the north, and Fuku River in the west". It was also observed that there is a risk of flood-related death even at a flood depth and velocity limit where underwater walking is possible.