The transport and resuspension of sediments in a shallow lake

The time-dependent flow and dispersion of suspended sediments in the western basin of Lake Erie are being studied by means of numerical models utilizing data from remote-sensing studies and flume experiments. Mechanisms of sediment dispersion included in the models are convection and turbulent diffusion, river loading, gravitational settling, and physical resuspension and deposition at the sediment-water interface. The time-dependent currents are computed by means of a free surface hydrodynamic model. A wave-hindcasting model is used to compute the wave parameters needed for estimation of shear stress generated at the sediment-water interface under given wind conditions. The rate of sediment resuspension as a function of bottom shear stress and sediment properties is based on data from flume experiments using lake sediments. A series of numerical calculations with the models were performed on a two-dimensional lake with a variable bottom representing a transverse cross section of Lake Erie. It was found that wind direction and fetch length can significantly affect the sediment dispersion patterns. The two-dimensional and the three-dimensional models were both used to simulate realistic short-term events in Lake Erie, and the model outputs compare favorably with the synoptic surface sediment dispersion patterns deduced from the multispectral scanner data.