EXAMINATION OF THE SPATIAL DISTRIBUTION OF HYDRAULIC QUANTITY AND BEHAVIOR OF LARGE WOOD AROUND THE CHIKUMA RIVER BREACH POINT BY TYPHOON NO. 19 IN 2019

Abstract

 In this study, the flow of floodwater at the breach point of the Chikuma River during Typhoon No. 19 in 2019 was calculated numerically to obtain the spatial distribution of physical quantities related to the shear stress and driftwood accumulation conditions. The behavior of driftwood was also analyzed based on a particle based model. The accumulation of large wood pieces was observed in areas where the shear stress decreased rapidly. In addition, it was confirmed that the large wood accumulation area corresponds to the point of divergence of the large wood flow path. Based on the buoyancy force and the drag force acting on the large wood piece, the possible locations of vertical accumulation of large wood were calculated, and it was confirmed that the results of the proposed evaluation method were consistent with the actual situation.