COMPARETIVE EVALUATION OF RAINFALL-RUNOFF CHARACTERISTICS BETWEEN TYPHOON HAGIBIS AND TYPHOON IDA

Abstract

 This research focused on the rainfall runoff characteristics of Typhoon Hagibis (2019) and Typhoon Ida (Kanogawa Typhoon)(1958), and evaluated flood control effectiveness of kanogawa river diversion channel. As a result of a numerical experiment, it was showed that even if the total rainfall in the period is the same, the amount of runoff to the river channel is larger in a rainfall event in which about 50 mm/h rain continues for more than half a day in the Kanogawa River basin. In addition, It is estimated that the flood control function of the overflow embankment of the Kano River drainage channel is almost nonexistent, and that the function of the gate is significant. Moreover, When flood occurs in the area upstream from the branch point of the Discharge Channel, such as in the case of a natural dam during Typhoon Ida, the flood control function of the discharge channel cannot function sufficiently because the flooding spreads to the middle part of the river. Therefore, it is shown that the importance of improving the flood control function in the upstream area and the main river maintenance.