A Two-Layer Turbulence-Based Model To Predict Suspended Sediment Concentration In Flows With Aquatic Vegetation

Traditional bed shear stress-based models (e.g., Rouse model) derived from the classic parabolic profile of eddy viscosity in open-channel flows fail to accurately predict suspended sediment concentration (SSC) in flows with aquatic vegetation. We developed a two-layer, turbulence-based model to predict SSC profiles in emergent vegetated flows. Turbulence generated from vegetation, bed, and coherent structures caused by stem-bed-flow interaction are considered into the near-bed turbulent kinetic energy (TKE) to calculate the effective bed shear velocity, ubeff*. The model, validated by experimental data, further showed that the thickness height of the near-bed layer (effective bottom boundary layer), H-b, varies with flow velocity and canopy density. Two additional models are provided to estimate H-b and ubeff*. The model is expected to provide critical information to future studies on sediment transport, landscape evolution, and water quality management in vegetated streams, wetlands, and estuaries.