Numerical modeling of hyper-concentrated sediment transport in the lower Yellow River

The simulation of hyper-concentrated sediment transport is very important in managing rivers with high sediment concentrations. Based on the theory of non-equilibrium transport of non-uniform sediment, a 1-D mathematical model is developed to simulate long-term and long-distance sediment transport and channel bed variation for both ordinary and hyper-concentrated flows. The model considers the effect of lateral inflow on flow movement by adding an extra term in the momentum equation. Also considered is the effect of high concentration on the flow density, sediment settling velocity and particle volume. The coefficients used in the model can be easily estimated by data analyses and empirical expressions. Therefore the uncertainty in finding coefficients may be avoided and the applicability is greatly increased. The use of a general formula for sediment-carrying capacity insures the model is capable of simulating sediment transport in both low- and hyper-concentrated flows. After calibration and verification by using large quantities of measured data from the Yellow River and Weihe River, the model is finally used to satisfactorily simulate the channel bed variation processes in the lower Yellow River since the operation of the Xiaolangdi Reservoir.