STUDY ON FLOOD CONTROL BASED ON INVESTIGATION OF INLAND FLOODS IN ROKKAKU RIVER BASIN DUE TO 2019 SAGA HEAVY RAIN

Abstract

 R1 Saga floods caused serius damage in the Rokkaku River basin. We carried out field surveys in the flood area and numerical simulation. The field surveys indicated that the flooding whose depth was higher than 2m spreaded in the left side of Takeo River, and hence the flooded area and water volume were 56.8km² and 40.9 million m³. In addition, the numerical simulation demonstrates that the maximum flood volume of inland waters is seven times greater than the maximum capacity of drainage pumps, indicating that it is difficult to drain the inland flood waters using these pumps. We need to develop a flood control strategy considering both of flooding from riverine and inland waters.