The transport of fine-grained sediments in shallow waters

Abstract

A numerical model of the resuspension, deposition, and transport of fine-grained, cohesive sediments has been developed and applied. An essential part of this model is an accurate and physically realistic description of the sediment bed and the resuspension of the bottom sediments due to physical processes. The description is based on data from recent experimental and field work on fine-grained sediments. Pertinent results from this work have been incorporated into the present model, and as part of the calculation, changes in the resuspension properties of the sediment bed with time due to resuspension, deposition, and compaction can be approximately determined. Vertically integrated differential equations were used to approximate the hydrodynamic and sediment transport equations. A volume integral method was used to derive finite difference equations which are second-order accurate, explicit, and locally conservative. A unique feature of the numerical model is that it can successfully treat conditions at open boundaries where both incoming and outgoing waves or disturbances may be present.

The model has been applied to the resuspension, deposition, and transport of fine-grained sediments in (1) the Raisin River, a small polluted stream flowing into Lake Erie; (2) a river flowing into a lake or ocean with a cross-flow; and (3) a time-dependent flow in a simple estuary as affected by tidal currents. The formation of erosional and depositional areas under various conditions is demonstrated.