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Abstract
In the temperate upper Midwest of the US, where groundwater and surface water are intimately connected, the overall water balance maintains abundant volume, but stress is expressed through impacts to streams, lakes, and springs. In Wisconsin, the state legislature mandated a study to evaluate the relationship between groundwater withdrawals and lake levels in the intensive agricultural Central Sands region of the state where irrigated agriculture is a dominant land use. The project quantified the impact pumping has on three study lakes in the area and identified potential remedies to reduce those impacts. In support of that goal, we established a modeling framework that could represent regional boundaries at a coarse scale while simultaneously representing lake geometry and physical properties at a much finer scale. This was accomplished through a combination of static and dynamic model linking taking advantage of the multi-model capabilities in the MODFLOW 6 framework. Recharge was simulated using the Soil Water Balance (SWB) code including simulating irrigation following the FAO-56 crop evapotranspiration technique. History matching using reported pumping and observed weather from 2012-2018 was performed to tune parameters.
With representative models created for three specific lakes, we performed a comparison of lake level history under three assumed land use configurations: current agriculture, no agriculture, and maximum future agriculture. All three configurations were simulated over a representative climate history of 40 years to compare potential impacts to lake ecology and recreation. The resulting lake elevation histories were then evaluated by a multi-disciplinary team to evaluate significance of impacts. The results of this work could directly inform groundwater management in Wisconsin going forward.
Bios
Dr. Mike Fienen is a Research Hydrologist specializing in groundwater modeling, parameter estimation, statistical and probabilistic modeling, and uncertainty analysis at the USGS Upper Midwest Water Science Center in Madison, Wisconsin USA.
A native of Minnesota, Mike earned a B.A. in Geology with a Russian Language minor from Macalester College and then embarked on a consulting career where he conducted field investigations throughout the US and the Pacific Ocean and performed groundwater and air dispersion modeling studies. He earned an M.S. and Ph.D. in the Environmental Fluid Mechanics and Hydrology program in the Civil and Environmental Engineering Department at Stanford University then started a postdoc and ongoing research career at USGS. When not working on modeling projects, Mike can usually be found touring on a tandem bicycle, running rivers, playing music, cooking, or some combination of those pursuits.
Aaron Pruitt is a hydrogeologist and Natural Resources Research Scientist at the Wisconsin Department of Natural Resources, where he works on getting cutting edge groundwater modeling to play nicely with a (sometimes less than cutting edge) regulatory environment.
Born and raised in North Carolina, Aaron majored in English and Geology at Appalachian State University, and then got his M.S. in Geosciences at the University of Wisconsin. He then spent five years in consulting in Washington State, working on everything from old paper mills to active army bases to water rights in the high desert.
In 2018 Aaron joined the Water Use Section of the Wisconsin DNR dealing with groundwater quantity regulations, including high-capacity well reviews and implementation of the Great Lakes Compact. When he’s not navigating the bureaucracy, Aaron can usually be found with his guitar, on a bike, or hanging out at the playground with his kid.