Numerical Modelling of the Grand River Plume in Lake Erie during Unstratified Period

The Grand River is a major contributor of nutrients and dissolved and suspended solids to the eastern basin of Lake Erie. To better understand the impact of the Grand River plume on the surrounding receiving waters, we integrated data analysis and modelling of the Grand River plume transport in the eastern basin of Lake Erie using a high-resolution depth-integrated nonlinear barotropic finite element model. An extended domain of receiving waters with closed boundary was applied in this numerical study due to the lack of observations needed for specifying the open boundary conditions. The size of closed domain was chosen by considering balance between the computing time and stabilizing the hydrodynamic flow. Numerical simulations of the influence of wind on the plume transport in the vicinity of the Grand River mouth were performed. The root mean square error values of alongshore and cross-shore current components were 5 and 2.85 cm s -1 , respectively. The transport simulations compare favorably (±20%) with observations of conductivity in the vicinity of the Grand River mouth. This study demonstrates that a two-dimensional numerical model can reasonably predict the river plume transport in a large lake during unstratified periods. Plume movement is primarily controlled by the wind-driven coastal current. Our simulations indicate that the frequent reversals of this current should effectively limit the plume’s alongshore extent and may result in a continuous coastal band of turbid water extending alongshore in either direction in the vicinity of the river mouth.