Verification of Lake Superior Outflow Equations

by Scott J. Thieme, U.S. Army Engineer District, Detroit, United States,

Document Type: Proceeding Paper

Part of: Hydraulic Engineering


The outflow from Lake Superior, the largest volume freshwater lake in the world, is regulated by the International Lake Superior Board of Control in accordance with the Treaty of 1909 between Britain and the U.S.. Controls are provided through a series of hydropower plants and navigation locks, and the Compensating Works, a 16-gated structure located at the head of the St. Marys River Rapids. Following completion of the gates in 1927, an initial discharge rating was undertaken, resulting in a set of 16 standard open-gate rating equations in 1931, which are still used today. A rating equation verification program begun in 1974, was temporarily halted due to an era of unprecedented high lake levels and further structure rehabilitation. Following a series of trial programs in the later 1980's, an engineered measurement methodology was agreed to in 1990. Subsequent measurements in 1990 and 1991, showed that the measured flows correlated well with the original rating equations. To extend the range of flows for verification of results, the measurement program is planned to continue whenever the level of Lake Superior rises or falls appreciably from the middle range where data were previously collected.

Subject Headings: Flow measurement | Lakes | Fluid flow | Ratings | Water discharge measurement | Outflow | Water discharge | Great Lakes | Lake Superior

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