Non-uniformity and layering in sediment transport modelling 2: river application

The objectives of this research are to verify a numerical sediment transport model based on field data from a reach of the Austrian Danube River, to identify the influence of non-uniform bed-load transport modelling and the selected bed schematization on the simulation results and to investigate the cause and the numerical reproducibility of spatio-temporal variations found in field data. Simulation results based on variants of the transport equation by Meyer-Peter and Muller were compared to basket sampler and radio tracer stone observations. The best agreement was obtained for a non-uniform formulation with an exchange layer, while the uniform formulation of the transport equation underestimated the transport rates for discharges lower than the mean flow since it predicts a later onset of bed-load transport. The consideration of an exchange layer in the numerical code led to the prediction of bed-load sheets due to sorting waves, allowing the model to account for the spatio-temporal variability of field data.