Numerical Analysis of Effect of Bridge on Inundation Flow in the Kagetsu River on July 2017

Abstract

The flood behavior often affected by bridges, due to the accumulation of debris around bridge piers or the reduction of flow late. On the other hand, the effect of a bridge on a flood was not well studied. In this research, the simulation of the flood in the Kagetsu River in July, 2017 was conducted using 2D flow model in order to evaluate the effect of a bridge on the flood capacity, water level and flood scale. The flood behavior in residential area was also simulated. As a result, the bridge increased inundation velocity and inundation area, especially in the area around the bridge. When water level exceeds the height of bridge, flow discharge was limited by the area of bridge opening, which caused flow capacity decreasing. The stream force of flood was relatively strong at the area around the bridge.