Mid-Holocene Hydrologic Model of the Shingobee Watershed, Minnesota |
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| Authors: | Sheryl K Filby Sharon M Locke Mark A Person Thomas C Winter Donald O Rosenberry John L Nieber William J Gutowski Emi Ito |
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| Institution: | a Department of Geology & Geophysics, University of Minnesota, Minneapolis, Minnesota, 55455;b University of Southern Maine, Portland, Maine, 04104;c Department of Geological Sciences, Indiana University, 1001 E. 10th Street, Bloomington, Indiana, 47405;d United States Geological Survey, Denver, Colorado, 80225;e Department of Agricultural and Biosystems Engineering, University of Minnesota, St. Paul, Minnesota, 55108;f Department of Atmospheric and Geological Sciences, Iowa State University, Ames, Iowa, 50011 |
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| Abstract: | A hydrologic model of the Shingobee Watershed in north-central Minnesota was developed to reconstruct mid-Holocene paleo-lake levels for Williams Lake, a surface-water body located in the southern portion of the watershed. Hydrologic parameters for the model were first estimated in a calibration exercise using a 9-yr historical record (1990–1998) of climatic and hydrologic stresses. The model reproduced observed temporal and spatial trends in surface/groundwater levels across the watershed. Mid-Holocene aquifer and lake levels were then reconstructed using two paleoclimatic data sets: CCM1 atmospheric general circulation model output and pollen-transfer functions using sediment core data from Williams Lake.Calculated paleo-lake levels based on pollen-derived paleoclimatic reconstructions indicated a 3.5-m drop in simulated lake levels and were in good agreement with the position of mid-Holocene beach sands observed in a Williams Lake sediment core transect. However, calculated paleolake levels based on CCM1 climate forcing produced only a 0.05-m drop in lake levels. We found that decreases in winter precipitation rather than temperature increases had the largest effect on simulated mid-Holocene lake levels. The study illustrates how watershed models can be used to critically evaluate paleoclimatic reconstructions by integrating geologic, climatic, limnologic, and hydrogeologic data sets. |
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| Keywords: | Abbreviations: Groundwater waterAbbreviations: paleohydrologyAbbreviations: pollen transfer functionsAbbreviations: paleolimnologyAbbreviations: climate change |
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