Development of a Physically Based Sediment Transport Model for Green Bay, Lake Michigan
Green Bay is the largest freshwater estuarine system on earth, drains one‐third of the Lake Michigan basin and delivers one‐third of the lake's phosphorus load. Southern Green Bay is a designated area of concern due to ecosystem degradation that includes eutrophication, harmful algal blooms, hy...
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| Published in: | Journal of geophysical research. Oceans Vol. 126; no. 10 |
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| Main Authors: | , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
Washington
Blackwell Publishing Ltd
01-10-2021
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| Subjects: | |
| Online Access: | Get full text |
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| Summary: | Green Bay is the largest freshwater estuarine system on earth, drains one‐third of the Lake Michigan basin and delivers one‐third of the lake's phosphorus load. Southern Green Bay is a designated area of concern due to ecosystem degradation that includes eutrophication, harmful algal blooms, hypoxia, lost or altered habitat, and reduced water quality. While marine estuaries are subject to tidal influence and saltwater intrusion, this freshwater estuary is subject to lake intrusion of freshwater with different quality parameters. Understanding the simultaneous effects of tributary flows and lake intrusions is crucial to comprehend the dynamics of freshwater estuaries. A single hydrodynamic, wind‐wave, and sediment transport model was developed for the lake and its estuary. This approach provides fine resolution in the estuary and simulates directly the combined effects of tributary flows and lake intrusions. The approach overcomes open‐boundary limitations of nested models, and of whole‐lake models that lack sufficient resolution or wind‐wave and sediment transport simulation. The model confirms findings of previous studies and demonstrates how the circulation, thermal regime, wave action, and sediment transport in the estuary depend on meteorological forcing, tributary flows, and lake intrusions. The stage is set to apply this approach to study biogeochemical processes in lakes and estuaries.
Plain Language Summary
Green Bay is a unique ecosystem located in the largest freshwater system on earth, the Laurentian Great Lakes. Almost one‐third of tributary waters to Lake Michigan flow through Green Bay. Human activities in the watershed produce excessive amounts of contaminated and/or nutrient‐rich sediments that are discharged to the bay. Sediments are not efficiently transported to Lake Michigan due to physical conditions in Green Bay, leading to ecosystem degradation, environmental and public health risks. We studied the movement, transport, and fate of sediments in Lake Michigan, with a special attention to Green Bay, by developing a physically based, 3D sediment transport model. This model development effort helps to predict circulation of contaminants and nutrients that are attached to the sediments, their settlement and burial, and the detachment from the bottom during storm events. The knowledge gained in this study will enhance our understanding of water quality conditions and nutrient recycling in freshwater estuaries, and will improve future restoration efforts and management plans.
Key Points
Understanding the simultaneous effects of tributary flows and lake intrusions is crucial to comprehend the dynamics of freshwater estuaries
Circulation, thermal regime, wave action, and sediment transport depend on meteorological forcing, tributary flows, and lake intrusions
The stage is set to apply this approach to study biogeochemical processes in lakes and estuaries |
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| ISSN: | 2169-9275 2169-9291 |
| DOI: | 10.1029/2021JC017518 |