Flow and Transport Modeling in Heterogeneous Sediments Using an Integral Approach.

An integral approach which can simultaneously model turbulent flow and transport at the sediment–water interface has been recently developed and validated for homogeneous sediment which was achieved by comparing numerical results to flume experiments on flow and transport over a rippled streambed and through the sediment for neutral, gaining, and losing conditions. In the present study, we validated the approach for heterogeneous conditions by comparing numerical simulations of flow and transport in heterogeneous sediment to analytical solutions as well as flume experiments on flow and transport through rippled streambed consisting of heterogeneous sediment. For this complex setup, simulation and experimental results agree well showing that flow and tracer transport prefer paths through areas with bigger grain diameters and higher porosities. The effect of flow redirections under losing and gaining conditions on hyporheic flow and residence times is discussed. Article impact statement: An integral modeling approach is further validated to account for transport processes at the heterogenous sediment–surface water interface. [ABSTRACT FROM AUTHOR]