SUSPENDED SEDIMENT TRANSPORT MODELING IN LAKE MICHIGAN

J. Lou1, D. J. Schwab1, and D. Beletsky2
1NOAA/Great Lakes Environmental Research Laboratory,
2205 Commonwealth Blvd., Ann Arbor, MI 48105.
2Department of Naval Architecture and Marine Engineering, University of Michigan; Cooperative Institute for Limnology and Ecosystems Research/NOAA Great Lakes Environmental Research Laboratory and University of Michigan, 2205 Commonwealth Blvd., Ann Arbor, MI 48105.

ABSTRACT

Recent observations reveal an annually occurring major event of sediment resuspension in Lake Michigan in late winter and early spring. The sediment plume extends along the southern shore of the lake, and may significantly influence the biogeochemical processes in the coastal region.

A quasi-3D suspended sediment transport model has been developed and applied to Lake Michigan to study sediment transport processes. The model was linked to a 3-D circulation model and a wind wave model. The nonlinear wave-current interaction influencing sediment transport has been taken into account in two dynamical processes: the turbulence intensity and the enhancement of the bottom shear stress. The sediment entrainment, suspension and deposition processes have been parameterized by laboratory measurement and field data. The model was calibrated with the measured sediment concentration data during a sediment resuspension episode in November-December 1994. The settling velocity, grain size, and critical shear stress have been optimized based on the measured data.

In addition, the model was applied to the March 1998 Lake Michigan sediment plume event. The model results were compared with the available satellite imagery. The separate effects of waves, currents, as well as the combined effect of waves and currents on sediment resuspension and nearshore-offshore transport in Lake Michigan are investigated.