Siltation in the Rhine
In addition to the flowing water, almost all flumes include sediment transport that affects the flow behaviour. Sediment transport consists of suspended-load transport and bed-load transport. Suspended matter are solids that are suspended in the water and that have no contact with the bottom. Bed load on the other hand, consists of solids that are moved along the bottom. When studying the flow behaviour in flumes, it is bed-load transport that is the predominant component. Sediment that is deposited (siltation) or removed (erosion and/ or scour) may, for example, change the flow cross-section or the water surface profiles. Sediment transport also results in a modified bed structure (formation of ripples or dunes, change of roughness).
In the case of normal discharge, in addition to the equations detailed above, it is also necessary to consider the transport balance on the control volume – is the same amount of sediment that leaves the control volume, also fed back in?