The U.S. Army Corps of Engineers is tasked with maintaining the navigability of the waters of the United States. There are more than 100 federal harbors or federally maintained navigation channels in the Great Lakes. Nearly all of the precipitation falling in the Great Lakes Basin eventually passes through a federally-maintained harbor/channel, carrying with it sediment and contaminants. The U.S. Army Corps of Engineers spends approximately $40 million removing 2-4 million cubic yards of sediment from these channels annually.
This study proposes to apply both field and laboratory investigations to determine the historical and predicted future rates of sediment accumulation, as well as the remaining storage capacity, behind the network of dams in the Great Lakes watershed that are tributary to federal harbors. Approximately 10 reservoirs will be selected for the detailed field reconnaissance efforts. Information gleaned from these sites will be analyzed for applicability to the more distributed Great Lakes Watershed. The selection process for these reservoirs will be critical to ensure the resulting findings can be applied more globally. The majority of the reservoirs chosen for this study will be from Great Lakes sub-watersheds that are representative of “typical” agricultural basins, but with unique hydrological and hydraulic stream features that can be used to identify/associate sedimentation features with watershed features. Additionally, one-two reservoirs that are primarily forested and one-two reservoirs that are primarily urban will be chosen to compare sedimentation rates to the findings associated with the agricultural watersheds. Previous research has shown that sediment flux from watersheds with mixed land use/cover is quite different than that in watersheds strictly agricultural in character (Coulter et al. 2004).