Daniel T. Feinstein

A hybrid finite-difference and analytic element groundwater model.

Regional finite-difference models tend to have large cell sizes, often on the order of 1-2 km on a side. Although the regional flow patterns in deeper formations may be adequately represented by such a model, the intricate surface water and groundwater interactions in the shallower layers are not. Several stream reaches and nearby wells may occur in a single cell, precluding any meaningful modeling of the surface water and groundwater interactions between the individual features. We propose to replace the upper MODFLOW layer or layers, in which the surface water and groundwater interactions occur, by an analytic element model (GFLOW) that does not employ a model grid; instead, it represents wells and surface waters directly by the use of point-sinks and line-sinks. For many practical cases it suffices to provide GFLOW with the vertical leakage rates calculated in the original coarse MODFLOW model in order to obtain a good representation of surface water and groundwater interactions. However, when the combined transmissivities in the deeper (MODFLOW) layers dominate, the accuracy of the GFLOW solution diminishes. For those cases, an iterative coupling procedure, whereby the leakages between the GFLOW and MODFLOW model are updated, appreciably improves the overall solution, albeit at considerable computational cost. The coupled GFLOW-MODFLOW model is applicable to relatively large areas, in many cases to the entire model domain, thus forming an attractive alternative to local grid refinement or inset models.

Metamodels to Bridge the Gap Between Modeling and Decision Support.

Insights from process-based models are a mainstay of many groundwater investigations; however, long runtimes often preclude their use in the decision-making process. Screening-level predictions are often needed in areas lacking time or funding for rigorous process-based modeling. The U.S. Geological Survey (USGS) Groundwater Resources and National Water Quality Assessment Programs are addressing these issues by evaluating the “metamodel” to bridge these gaps. A metamodel is a statistical model founded on a computationally expensive model. Although faster, the question remains: Can a statistical model provide similar insights to a numerical model with faster results? Metamodeling was developed to overcome long runtimes for sensitivity analysis (Blanning 1975); our focus is decision support applications. Two representative groundwater applications are: (1) the contribution of surface water to wells in shallow groundwater systems (e.g., Fienen and Plant 2014), and (2) unsaturated zone nitrate flux to groundwater (e.g., Nolan et al. 2012). The first step is to generate a representative sample of input/output combinations from the numerical model over a range of conditions. This variability is especially important when propagating uncertainty to predictions. Variability can be represented by many model runs using different input values or by few model runs with samples scattered in space/time experiencing the range of natural system variability. In the second step, a statistical learning technique is selected with which a predictive model can be “learned” from the data derived from the model. Techniques include

Estimation of the groundwater resources of the bedrock aquifers at the Kettle Moraine Springs State Fish Hatchery, Sheboygan County, Wisconsin

Groundwater resources information was needed to understand regional aquifer systems and water available to wells and springs for rearing important Lake Michigan fish species at the Kettle Moraine Springs State Fish Hatchery in Sheboygan County, Wisconsin. As a basis for estimating the groundwater resources available, an existing groundwater-flow model was refined, and new groundwater-flow models were developed for the Kettle Moraine Springs State Fish Hatchery area using the U.S. Geological Survey (USGS) finite-difference code MODFLOW. This report describes the origin and construction of these groundwater-flow models and their use in testing conceptual models and simulating the hydrogeologic system. The study area is in the Eastern Ridges and Lowlands geographical province of Wisconsin, and the hatchery property is situated on the southeastern edge of the Kettle Moraine, a north-south trending topographic high of glacial origin. The bedrock units underlying the study area consist of Cambrian, Ordovician, and Silurian units of carbonate and siliciclastic lithology. In the Sheboygan County area, the sedimentary bedrock sequence reaches a thickness of as much as about 1,600 feet (ft). Two aquifer systems are present at the Kettle Moraine Springs State Fish Hatchery. A shallow system is made up of Silurian bedrock, consisting chiefly of dolomite, overlain by unconsolidated Quaternary-age glacial deposits. The glacial deposits of this aquifer system are the typical source of water to local springs, including the springs that have historically supplied the hatchery. The shallow aquifer system, therefore, consists of the unconsolidated glacial aquifer and the underlying bedrock Silurian aquifer. Most residential wells in the area draw from the Silurian aquifer. A deeper confined aquifer system is made up of Cambrianand Ordovician-age bedrock units including sandstone formations. Because of its depth, very few wells are completed in the Cambrian-Ordovician aquifer system (COAS) near the Kettle Moraine Springs State Fish Hatchery. Three groundwater-flow models were used to estimate the water resources available to the hatchery from bedrock aquifers under selected scenarios of well placement and seasonal water requirements and subject to constraints on the effects of pumping on neighboring wells, local springs, and creeks. Model input data (recharge, water withdrawal, and boundary conditions) for these models were compiled from a number of data and information sources. The first model, named the “KMS model,” (KMS stands for Kettle Moraine Springs) is an inset model derived from a published USGS regional Lake Michigan Basin model and was constructed to simulate groundwater pumping from the semiconfined Silurian aquifer. The second model, named the “Pumping Test model,” was constructed to evaluate an aquifer pumping test conducted in the COAS as part of this project. The Pumping Test model was also used to simulate the local effects of 20 years of groundwater pumping from this deep bedrock aquifer for future hatchery operations. The third model, named the “LMB modified model,” is a version of the published Lake Michigan Basin (LMB) model that was modified with aquifer parameters refined in an area around the hatchery (approximately a 5-mile radius circle, corresponding to the area stressed by the aquifer pumping test). This LMB modified model was applied to evaluate regional effects of pumping from the confined COAS. The available Silurian aquifer groundwater resource was estimated using the KMS model with three scenarios—named “AllConstraints,” “Constraints2,” and “Constraints3”—that specified local water-level and flow constraints such as drawdown at nearby household wells, water levels inside pumping well boreholes, and flow in local streams and springs. Each scenario utilized the MODFLOW Groundwater Management Process (GWM) to select three locations from six candidate locations that provided the greatest combined flow while satisfying the constraints. The three constraint scenarios provided estimates of 430 gallons per minute (gal/min), 480 gal/min, and 520 gal/min pumping from three wells—AllConstraints, Constraints2, and Constraints3, respectively. The same three wells were selected for the scenarios that estimated 480 gal/min and 520 gal/min; the scenario that estimated 430 gal/min shared two of these same wells, but the third selected well was different. 2 Estimation of the Groundwater Resources of the Bedrock Aquifers at the Kettle Moraine Springs State Fish Hatchery The available COAS groundwater resource was estimated by two scenarios with each conducted over a period of 20 years with the Pumping Test model and the LMB modified model. The Pumping Test model was used to simulate local effects of pumping, and the LMB modified model was used to simulate regional effects of pumping. The scenarios simulate a range of total and seasonal pumping rates potentially linked to site activities. Scenario 1 simulates two wells completed in the Cambrian-Ordovician aquifer system, each pumping for 8 months at 300 gal/min, followed by pumping for 4 months at 600 gal/min. The average yearly pumping rate of Scenario 1 is 800 gal/min. Scenario 2 simulates three wells completed in the Cambrian-Ordovician aquifer system pumping for 8 months at 200 gal/min, followed by pumping for 4 months at 500 gal/min. The average yearly pumping rate of Scenario 2 is 900 gal/min. The Pumping Test model simulations confirmed that drawdown in the boreholes of the pumping wells at the selected 2-well or 3-well rates will meet the desired condition that the pumping water level remains at least 100 ft above the highest CambrianOrdovician unit open to the well. The LMB modified model was used to evaluate the regional drawdown of the pumping from the confined COAS under the same 2-well and 3-well scenarios. At the nearest known existing COAS well, Campbellsport production well #4, the simulated drawdown for Scenario 1 after 20 years of cyclical pumping with two pumping wells averaging a total of 800 gal/min is 16.9 ft, whereas the simulated drawdown for Scenario 2 after 20 years of pumping with three pumping wells averaging a total of 900 gal/min is 19.0 ft. The total deep aquifer thickness at the Campbellsport location is on the order of 620 ft, meaning that the simulated drawdown for either scenario is about 3 percent of the confined aquifer thickness. The models developed as part of this project are archived in the project data release. The archive includes the model input and output files as well as MODFLOW source code and executables. (Haserodt and others, 2017). Introduction As part of the Wisconsin Department of Natural Resources (WDNR) fish production system that annually stocks about 7.2 million fish into waters of the State, the Fisheries Management Program operates 13 fish hatcheries and rearing stations across the State. Sport fishing annually brings more than 330,000 nonresident anglers to Wisconsin—a number exceeded by only Florida and Michigan. Sport fishing supports 22,000 jobs in Wisconsin and annually generates

GWM-2005, MODFLOW-2005, MODFLOW-NWT, and SEAWAT-2000 groundwater flow models of the Bedrock Aquifers at the Kettle Moraine Springs State Fish Hatchery, Sheboygan County, Wisconsin

2.3 billion in economic benefits and

Simulating ground water-lake interactions: approaches and insights.

148 million in State and local tax revenues (Wisconsin Department of Natural Resources, 2014). In recognition of the importance of recreational fishing to the economy of Wisconsin and the importance of fish stocking as a fisheries management tool, the WDNR Bureau of Fisheries Management commissioned a study that resulted in the report “Comprehensive Study of Wisconsin’s Fish Propagation System” (Wisconsin Department of Natural Resources, 2010). An important conclusion of the study was that most of the fish production facilities of the WDNR need extensive renovation to meet fish stocking goals; however, hatchery renovation and design decisions are dependent on the quantity and quality of the water supply that is sustainably available. Another critical finding of the study was that most Wisconsin hatcheries lack adequate water supplies to support the volume of rearing space that already exists. Therefore, the WDNR Bureau of Fish Management recognized the importance of quantifying the amount of water that is sustainably available from local resources to meet the needs of planned operations at each of the fish hatcheries and rearing stations in Wisconsin. With this need in mind, the WDNR funded this detailed study of the water resources available to the Kettle Moraine Springs State Fish Hatchery (KMSSFH) in Sheboygan County, a cold water fish production facility focused on stocking important Lake Michigan species. These species are Chinook (Oncorhynchus tshawytscha) and Coho (Oncorhynchus kisutch) salmon and Chambers Creek and Ganaraska River strains of steelhead (Oncorhynchus mykiss) trout. The KMSSFH, along with the Les Voigt State Fish Hatchery in Bayfield County, have been prioritized by the WDNR because both are critical to providing fish stock to the Great Lakes, and both are directly affected by regulatory requirements intended to protect high-quality surface waters such as trout streams and springs. The estimate of groundwater resources at the KMSSFH provided by this study will enable the WDNR Bureau of Fisheries Management to better understand groundwater availability from regional aquifers. This estimate also will assist the WDNR Bureau of Fisheries Management in their determination of resource sustainability and their ability to meet applicable regulatory requirements. Purpose and Scope The purpose of this report is to document the estimation of groundwater resources available to the WDNR at its KMSSFH and to describe the hydrogeologic data and groundwaterflow models that have been used to make this estimate. In particular, this report describes the refinement and application of a published U.S. Geological Survey (USGS) regional model for estimating the groundwater resources available from the local bedrock aquifers and describes the development of a model used specifically to analyz

The Vertical Hydraulic Conductivity of an Aquitard at Two Spatial Scales

Three groundwater flow models (KMS model, Pumping Test model, and Modified LMB model) were developed for the Kettle Moraine Springs State Fish Hatchery using the U.S. Geological Survey codes MODLOW-NWT, GWM-2005, MODFLOW-2005, and SEAWAT-2000. The KMS inset model was derived from a published USGS regional Lake Michigan Basin model, and was constructed to simulate groundwater pumping from the semi-confined Silurian bedrock aquifer. The LMB modified model is a version of the published Lake Michigan Basin model that was modified with aquifer parameters refined in an area around the hatchery. The Pumping Test model, was constructed to evaluate a pumping test conducted in the Cambrian-Ordovician aquifer system and to simulate groundwater pumping from this deep bedrock aquifer at the hatchery.