Event Flow Hydrograph–Based Method for Modeling Sediment Transport

Abstract

A simple method, called the hydrograph-based method, is presented for estimating sediment transport during flood events in rivers. The method is characterized by the following features: (1) widely available flow hydrographs are used as primary input data; (2) the shear stress, shear velocity, and friction slope, calculated using a hydrograph, are employed to determine flow depth and velocity for a flood event; and (3) a conventional simple sediment transport formula is utilized in combination with the hydrograph-based flow parameters to estimate sediment transport during a flood event. The new hydrograph-based method is examined using a hypothetical hydrograph and demonstrated through applications to a number of flood events in two lowland rivers. The sediment concentrations predicted by the hydrograph-based method are found to be comparable or more accurate than those from the Hydrologic Engineering Center’s River Analysis System model, demonstrating the efficacy of the new method. The engineering significance of the hydrograph-based method is that it extends the range of applicability of conventional sediment transport formulas, developed for steady flows, to unsteady flood events. The data requirement is thus greatly reduced, and sediment transport computations for flood events are simplified.