The U.S. Army Corps of Engineers, Detroit District, recently completed a conveyance change analysis of the St. Clair River in an effort to understand how the river is changing and to further explain its impacts on Great Lakes water levels.
The analysis was conducted as part of the Corps’ operational mission of monitoring the connecting channels of the Great Lakes for changes in flow.
“It is important to monitor the connecting rivers of the Great Lakes because as the channels change over time, so could the water levels of each lake connected by those channels,” said John Allis, chief of the Great Lakes Hydraulics and Hydrology Office.
A total of $400,000 worth of high resolution swath bathymetry data was collected from the St. Clair River in 2007 and 2012 to form the basis of the analysis. A two-dimensional hydraulic model was developed and the data collected was used to estimate the impacts of these geometric changes on the flow capacity of the river.
The recently completed analysis focused on the period between 2007 and 2012. Overall, minimal change to the river bottom was identified during the five year period, however some consistent signs of river deepening were present. Further monitoring will occur to better understand the impacts on water levels over time.
“While the magnitude of any potential net deepening of the river bottom is very small, this trend is important for us to continue monitoring as further deepening could lead to lower water levels on Lakes Michigan and Huron,” noted Dr. Tim Calappi, the Corps lead engineer on this study.
This is the first of what will be routine analyses the Corps will complete every five to ten years as part of its operational responsibility in monitoring the river flow through the connecting channels of the Great Lakes.