Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1046103 | Quaternary Research | 2008 | 13 Pages |
Abstract
Proglacial lakes, formed during retreat of the Laurentide ice sheet, evolved quickly as outlets became ice-free and the earth deformed through glacial isostatic adjustment. With high-resolution digital elevation models (DEMs) and GIS methods, it is possible to reconstruct the evolution of surface hydrology. When a DEM deforms through time as predicted by our model of viscoelastic earth relaxation, the entire surface hydrologic system with its lakes, outlets, shorelines and rivers also evolves without requiring assumptions of outlet position. The method is applied to proglacial Lake Oshkosh in Wisconsin (13,600 to 12,900Â cal yr BP). Comparison of predicted to observed shoreline tilt indicates the ice sheet was about 400Â m thick over the Great Lakes region. During ice sheet recession, each of the five outlets are predicted to uplift more than 100Â m and then subside approximately 30Â m. At its maximum extent, Lake Oshkosh covered 6600Â km2 with a volume of 111Â km3. Using the Hydrologic Engineering Center-River Analysis System model, flow velocities during glacial outburst floods up to 9Â m/s and peak discharge of 140,000Â m3/s are predicted, which could drain 33.5Â km3 of lake water in 10Â days and transport boulders up to 3Â m in diameter.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Geology
Authors
James A. Clark, Kevin M. Befus, Thomas S. Hooyer, Peter W. Stewart, Taylor D. Shipman, Chris T. Gregory, Deborah J. Zylstra,