ESTIMATING PALEOFLOW THROUGH LAKE MAUMEE'S IMLAY CHANNEL

Lake Maumee formed against the margin of the retreating Laurentide Ice Sheet in the Lake Erie basin, as the highest lake series in ancestral Lake Erie (ALE). Lake Maumee drained from the Fort Wayne and Imlay outlets on its western end. Relative timing and discharge from these outlets is not completely understood. Previous work on the Imlay Channel near Imlay City, Michigan, used the current elevation of the surface drainage divide within the channel to define the elevation when it was active. Using geophysical techniques, coring, and available boring logs, there may be up to 15 meters of fill within the channel. The depth of water was estimated using the shoreline remnants at the mouth of the channel (6.5 kilometers south of the drainage divide) with a depth of approximately 25 meters below the water plane. The area of the channel was approximated as an inverse trapezoid, and the resulting cross-sectional area is 9,600 m². With these new results, the channel depth and cross-sectional geometry is greater than previously recognized. Previous work on glacial lake outlets indicate a wide range of water velocity estimates. For the study site, estimates of 3-10 m/s result in an estimated discharge (Q) of 9,600-96,000 m³/s using the continuity equation. These preliminary results can be used to estimate transfer of water from ALE westward into the Lake Michigan basin during deglaciation.