Understanding the Patterns of Sediment Dynamics in Lower Green Bay, Lake Michigan

Abstract

The Green Bay of Lake Michigan is a major freshwater estuary and an example of degraded terrestrial ecosystems due to intensive and unmanaged anthropogenic activities. Decades of soil erosion and unregulated industrial activities in the watershed led to excessive transport of contaminated and nutrient-rich sediments into Green Bay. Considerable sediment loading triggered deteriorated biogeochemical conditions in the bay such as hypoxia, harmful algal blooms, eutrophication, and degraded water quality. Restoration programs were developed, consisting of important research and field activities. Previous research has shown that managing water quality and ecological conditions in the lower Green Bay system depends on understanding the sediment transport regimes, resuspension and sedimentation rates, and exchange with Lake Michigan. Due to the lack of a reliable and robust sediment transport model for Green Bay, some of those issues have remained unanswered, and water quality studies have encountered uncertainty in the design of restoration plans. In this study, we used a sediment transport model to investigate in detail the sediment dynamics in Green Bay. The model is built upon the finite volume community ocean model (FVCOM) platform, includes the entire Lake Michigan, and focuses on Green Bay with a finer grid compared to that in the open lake areas. The current sediment transport model will play a crucial role in the identification of sedimentation zones and major sediment transport regimes in the bay.