BED MORPHOLOGY RESPONSES WITH DRIFTWOOD DEPOSITION PATTERNS ON AN ALTERNATING BAR THROUGH A FLUME EXPERIMENT AND A COMPUTATION

Abstract

 In this study, we conducted a flume experiment and a numerical simulation for driftwood dynamics on an alternating bar considering the root wad effect and bed deformation. For numerical simulation, we used Nays2DH with driftwood dynamics model. We then analyzed the relationship between the bed morphology and the wood deposition patterns. The experimental results showed diverse patterns of morphodynamics and motions of driftwood, such as pushing motion, scraping erosion, piping erosion. However, the present driftwood dynamics model could not reproduce partially the angle of driftwood deposition (most of the wood pieces laterally deposited against flow direction in the experiment) because the wood collision is underestimated in the simulation. In addition, the driftwood model does not consider the pushing and scraping motion of wood pieces, and diverse sediment transports such as scraping erosion and piping erosion. It, therefore, should be considered in further study.