Flow movement and sediment transport in compound channels

Abstract

There are many studies on the flow movement in compound channels, yet few are concerned with sediment transport. An experimental study on the flow movement and sediment transport in compound channels is presented. The experimental results indicate that the distribution of longitudinal velocity with depth in the main channel and the floodplains has a logarithmic component. The longitudinal velocity with flow depth in the interactive region does not obey a logarithmic distribution, but involves a wake function. In the boundary region, the longitudinal velocity obeys a parabolic distribution. In addition, based on the suspended sediment diffusion equation and the flow interaction between main channel and floodplains, expressions are derived to predict the lateral eddy viscosity and the sediment diffusion coefficients. Finally, an analytical solution for the lateral distribution of the depth-averaged velocity and sediment concentration in a compound channel is obtained. The results from the analytical solution agree well with experimentation.

Keywords:

• Compound channel
• floodplain
• flow exchange
• main channel
• sediment concentration distribution
• velocity distribution

Acknowledgements

This research was financially supported by the National Science Fund for Distinguished Young Scholars (50725930) and Science Fund for Creative Research Groups (50721006).