Abstract
Understanding and predicting of the bedload transport processes in rivers are of great importances for better sediment management works. In this study, we propose a numerical model to understand the bedload transport processes by simulating passive bedload tracer particles. A movable bed experiment with the use of colored bedload tracers is performed to understand the advection-dispersion processes of the tracers, i.e., how the tracer particles transport and disperse over the movable bed. We numerically reproduce observed behaviors of the bedload tracers by using a flux-type tracer transport model combined with a two-dimensional bed evolution model. The experimental results suggest that the bedload mixing process associated with a small-scale bedform dominates the advection-dispersion of tracers. The appropriate determination of the active layer thickness by considering this vertical bedload mixing process is necessary to reproduce the tracer advection speed.
