(Erosion and Sediment Transport Measurement in Rivers: Technological and Methodological Advances (Proceedings of the Oslo Workshop, June 2002), IAHS Publication 283, 2003, pp. 45–56).
This paper examines the potential for investigating flow and suspended sediment transport mechanisms on lowland flood plains using a combination of three-di-mensional numerical modelling and acoustic Doppler velocimetry. Model results show that, contrary to the common perception that suspended sediment transport is controlled predominantly by turbulent mixing processes, horizontal sediment exchanges between the channel and flood plain are largely a product of advection along topographically determined flow lines. Modelled and monitored profiles of time-averaged flow illustrate that vegetative roughness promotes characteristic velocity and turbulent kinetic energy profiles that contrast markedly with the logarithmic “law of the wall”. Instantaneous velocity and sediment concentration data obtained at a high sampling frequency confirm that while horizontal sediment transport is dominated by advection, the vertical sediment concentration profile in the lower half of the flow is controlled strongly by the balance between turbulent ejection and sweep events.
Acoustic doppler velocimeter, Flood plain, Numerical model, Suspended sediment
