(Sediment Transfer through the Fluvial System – Proceedings of a Symposium held in Moscow, August 2004 – IAHS Publication 288, 2004, pp. 410).
Sedimentation within cutoffs is controlled by mean and turbulent flow structures that drive suspended sediment transport by advection and diffusion and control particle settling and resuspension processes. The relationship between these flow and sedimentation processes is poorly understood at present due to the difficulty of collecting synchronous instantaneous velocity and sediment concerntration data above an undisturbed bed. These relationships are examined using a combined approach involving field monitoring and numerical modelling applied to a site on the River Culm, Devon, UK. Flow and suspended sediment time series were monitored using an array of Acoustic Doppler Velocimeters (ADVs), which provide synchronous instantaneous measurments of three-dimensional (3-D) velocity and sediment concentration at a frequency of 25 Hz. ADV data provide an estimate of the net sediment flux into the cutoff and allow the relationship between vertical turbulent sediment transport and momentum transport events to be examined. Results from a two-dimensional (2-D) finite volume numerical model are also presented and provide further insights into the stage-dependent nature of hydraulics at this site.
Alluvial Cut-off, ADV, Numerical Model, Suspended Sediment
