| Title | Rise of Great Lakes surface water, sinking of the upper midwest of the United States, and viscous collapse of the forebulge of the former Laurentide Ice Sheet |
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| Author | Argus, D F; Ratliff, B; DeMets, C; Borsa, A A; Wiese, D N; Blewitt, G; Crowley, J W ; Martens, H R; Kreemer, C; Landerer, F W |
| Source | Journal of Geophysical Research, Solid Earth vol. 125, issue 1, e2020JB019739, 2020 p. 1-16, https://doi.org/10.1029/2020JB019739 |
| Image |  |
| Year | 2020 |
| Alt Series | Natural Resources Canada, Contribution Series 20200461 |
| Publisher | Blackwell Publishing Ltd. |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf; html |
| Province | Ontario |
| Area | United States of America |
| Lat/Long WENS | -94.0500 -74.9667 51.1500 39.6000 |
| Subjects | Science and Technology; Nature and Environment; environmental geology; water levels; lake water depths; lake water; lakes; watersheds; hydrologic properties; Great Lakes; Great Lakes Basin; Great Lakes
Basins; Global positioning systems; Hydrology |
| Illustrations | location maps; graphs; diagrams |
| Released | 2020 07 31 |
| Abstract | Great Lakes water levels rose 0.7–1.5 m from 2013 to 2019, increasing surface water volume by 285 km3. Solid Earth's elastic response to the increased mass load is nearly known: The Great Lakes floor
fell 8–23 mm, and the adjacent land fell 3–14 mm. Correcting GPS measurements for this predicted elastic loading (1) straightens position-time series, making the evolution of position more nearly a constant velocity and (2) reduces estimates of
subsidence rate in Wisconsin, Michigan, and southern Ontario by 0.5–2 mm/yr, improving constraints on postglacial rebound. GPS records Wisconsin and Michigan to have subsided at 1–4 mm/yr. We find this sinking to be produced primarily by viscous
collapse of the former Laurentide ice sheet forebulge and secondarily by elastic Great Lakes loading. We infer water on land in the Great Lakes watershed to be total water change observed by GRACE minus Great Lakes surface water smeared by a Gaussian
distribution. Water stored on land each year reaches a maximum in March, 6 months before Great Lakes water levels peak in September. The seasonal oscillation of water on land in the Great Lakes basin, 100 km3 (0.20 m water thickness), is twice that
in a hydrology model. In the seasons, groundwater in the Great Lakes watershed increases by 60 km3 (0.12 m) each autumn and winter and decreases by roughly an equivalent amount each spring and summer. In the long term, groundwater volume remained
constant from 2004 to 2012 but increased by 50 km3 (0.10 m) from 2013 to 2019. |
| GEOSCAN ID | 327291 |
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