Lake Michigan-Huron Water Level Decline Due to Hydraulic Scour of the St. Clair River

摘要

Upper Great Lakes water levels are currently experiencing a precipitous decline. The Decembermonthly mean water levels for Lakes Superior, Michigan-Huron, and St. Clair were 17, 15, and2 inches, respectively, below average when compared to long-term (1918-2005) averages. At thesame time, Lake Erie and Lake Ontario were 7 and 12 inches above average. Concern aboutdeclining Lake Michigan-Huron water level from public and private organizations has lead toincreased study of the fluvial geomorphology of the St. Clair River and its contribution to thesteep decline of the Lake Michigan-Huron water level.The position of this paper, based upon historical construction and dredging records, is that theincreased hydraulic scour rate of the St. Clair River is an anthropogenic effect of riverbed armorlayer removal influenced by navigational and commercial dredging projects. Hydraulic scourincreases the outflow capacity of the St. Clair River which results in a water level decline onLake Michigan-Huron.The goal of this technical paper is to summarize the causal relationship between St. Clair Rivererosion and decreasing Lake Michigan-Huron water level. An additional concluding section hasbeen added to suggest an economical mitigation measure.