Numerical Study of Sediment Transport with Flow Hydrographs of Varying Length in a Laboratory Flume

Abstract Submission: Numerical modeling of sediment transport during realistic unsteady flow conditions is essential for increasing the ability to make predictions of sediment transport rates in streams and rivers. This paper presents the results of numerically modeling sediment transport based on a data from a series of experiments with flow hydrographs of varying in length in a laboratory flume with a sand bed. The model was successfully calibrated and validated using one flow hydrograph and then applied to other hydrographs of different lengths. A digital flume with the same geometry but different initial conditions and boundary conditions was generated to assist numerical simulations. In general, the numerical results are consistent with the experiments. Both numerical and experimental results demonstrate the influence of the duration of flow hydrographs on transport rates, which resulted in generally counter-clockwise hysteresis in the relationship between flow rate and sediment transport rate. For longer hydrographs, while the hysteresis direction remained counter-clockwise, the pattern became irregular due to the influence of bedforms that grew during peak flows. During these periods, the simulations of the numerical model became less accurate due to uncertainties introduced by the influence of relict bedforms.

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