EVALUATION ON A RETENTION FACILITY OF DRIFTWOOD IN RIVER BY A SIMULATION MODEL OF DRIFTWOOD BEHAVIOR

Abstract

 Driftwood or woody debris increase the destructive force during flood events, especially their accumulations at river bridges lead to the increase of flooding areas. Therefore, driftwood retention structures, like slit type sabo dams are built mainly in small and steep mountain torrents. However, recent serious flood events highlighted the need to retain driftwood directly in larger rivers, and to construct the effective retention facilities which have large capacity for accumulated driftwood. This paper aims to evaluate the effect of retention facility of driftwoods in river by a newly developed simulation model composed of depth-averaged flow analysis and 3D extended distinct element method for driftwood behavior. Results of calculations show the good performance of the retention facility in Kuro river.