Application of the Finite Volume Community Ocean Model (FVCOM) to the analysis of sediment processes in Green Bay, Lake Michigan

Green Bay is an important estuarine ecosystem in the northern US that drains almost one-third of Lake Michigan watershed, which in turn is one of the largest freshwater bodies on Earth. Intensive development of industrial and agricultural activities in its watershed led to the deterioration of the bay’s water quality. Evidences of Green Bay degradation became clear in the mid-20^th century and the response was the development of restoration programs. Five decades of research has demonstrated that the restoration of Green Bay is tied in with the understanding of sediment processes in the bay, and of the feedback between sediment interactions and ecosystem responses. Previous attempts to develop a sediment transport model for Green Bay were based on the Princeton Ocean Model (POM) and the Environmental Fluid Dynamics Code (EFDC), however, those efforts did not produce a robust sediment model. Low computational efficiency and/or the limitation of structured model grids were some of the main disadvantages of those model. In the present effort, we adopted a state-of-the-art modeling framework, the Finite Volume Community Ocean Model (FVCOM), to develop a physically-based sediment transport model for Lake Michigan, with a focus on Green Bay. FVCOM overcomes the limitations of the POM- and EFDC-based models, and provides modules that simulate circulation, wave, and sediment transport in one single platform, making it more efficient to run a sediment model. This study presents spatial patterns of different sediment processes in Green Bay, based on the model simulations. These results will be crucial in understanding biogeochemical processes in Green Bay, and in developing solutions for some of the current environmental problems in the bay such as hypoxia and harmful algal blooms.