NUMERICAL SIMULATIONS ON RESPONSE OF DUNE BEDFORMS TO FLOW VARIABILITY

Abstract

In this study, we performed numerical simulations on the change of bedform under an unsteady discharge condition using a vertical two-dimensional flow model for bedform evolutions. In order to clarify the effects of non-equilibrium sediment transport in the bedform response to the flow variability, we compared the bedform response characteristics calculated by non-equilibrium sediment transport model with that calculated by equilibrium sediment transport model. It was found that the non-equilibrium sediment transport model reproduced the increase in bedform wavelength with the increase of discharge and the gradual decrease in wavelength after the discharge decreases, which were similar characteristics observed in experiments.