Fluxes of Sediment Beneath Floating Silt Screens due to Density Gradients and Screen Motion

Abstract

Floating silt screens are widely applied to confine and control turbidity plumes and sedimentation due to dredging activities. Their efficient deployment requires detailed knowledge of the ambient hydrodynamic conditions. Incorrect deployment may lead to confinement deficiencies, screen burial, or damage. One aspect of deployment efficiency is the sediment transport rate beneath the silt screen. The sediment transport between the sides of a floating silt screen is mostly affected by ambient currents. In addition, gravity currents and shear-stress–induced screen motion also affect the sediment transport. The gravity current is governed by the suspended sediment concentration, whereas the shear-stress–inflicted flow scales with the ambient current. This study is concerned with the evaluation of the sediment transport, in terms of the effective screen depth, the suspended sediment concentration, and the ambient parallel current. Two computational models for density gradient and screen motion inflicted sediment transport are presented for the analyses of these transport mechanisms. Based on the generated data, a scaling law dependence for the water transport in dependence of the effective screen depth, the ambient current, and the suspended sediment concentration is proposed.