EFFECTS OF MID-CHANNEL BAR AND BRIDGE GIRDER ON FLOOD FLOW IN KUMA RIVER IN JULY, 2020

In this study, we clarified the actual circumstances of the Kuma River flood damage in Hitoyoshi City that occurred on July 4, 2020, and examined the effects of Nakagawara Park and three bridges on abnormal flood currents through hydraulic model experiments. The results obtained showed that the wa-ter level was raised rapidly upstream from the vicinity of Ohashi Bridge under all conditions of flow rates of 6,000 m3/s, 8,000 m3/s and 10,000 m3/s. In particular, at the flow rate of 8,000 m3/s, when there is no bridge, the water level will rise by about 2.08 m upstream of the bridge due to the influence of Nakagawara Park alone, and when the bridge girder is submerged, compared to the case without a bridge. It was revealed that the distance is 1.28m di-rectly above the bridge and 2.0m directly above the Mizunote Bridge.