Geology topics

J. T. Krohelski

Publications and source records attributed to J. T. Krohelski.

12 recordsLinked to original sources

USGS2005

Simulating ground water-lake interactions: Approaches and insights

Approaches for modeling lake-ground water interactions have evolved significantly from early simulations that used fixed lake stages specified as constant head to sophisticated LAK packages for MODFLOW. Although model input can be complex, the LAK package capabilities and output are superior to methods that rely on a fixed lake stage and compare well to other simple methods where lake stage can be calculated. Regardless of the approach, guidelines presented here for model grid size, location of three-dimensional flow, and extent of vertical capture can facilitate the construction of appropriately detailed models that simulate important lake-ground water interactions without adding unnecessary complexity. In addition to MODFLOW approaches, lake simulation has been formulated in terms of analytic elements. The analytic element lake package had acceptable agreement with a published LAK1 problem, even though there were differences in the total lake conductance and number of layers used in the two models. The grid size used in the original LAK1 problem, however, violated a grid size guideline presented in this paper. Grid sensitivity analyses demonstrated that an appreciable discrepancy in the distribution of stream and lake flux was related to the large grid size used in the original LAK1 problem. This artifact is expected regardless of MODFLOW LAK package used. When the grid size was reduced, a finite-difference formulation approached the analytic element results. These insights and guidelines can help ensure that the proper lake simulation tool is being selected and applied.

Ground Water↗

USGS2004

Simulation of ground-water flow, surface-water flow, and a deep sewer tunnel system in the Menomonee Valley, Milwaukee, Wisconsin

Numerical models were constructed for simulation of ground-water flow in the Menomonee Valley Brownfield, in Milwaukee, Wisconsin. An understanding of ground-water flow is necessary to develop an efficient program to sample ground water for contaminants. Models were constructed in a stepwise fashion, beginning with a regional, single-layer, analytic-element model (GFLOW code) that provided boundary conditions for a local, eight layer, finite-difference model (MODFLOW code) centered on the Menomonee Valley Brownfield. The primary source of ground water to the models is recharge over the model domains; primary sinks for ground water within the models are surface-water features and the Milwaukee Metropolitan Sewerage District Inline Storage System (ISS). Calibration targets were hydraulic heads, surface-water fluxes, vertical gradients, and ground-water infiltration to the ISS. Simulation of ground-water flow by use of the MODFLOW model indicates that about 73 percent of recharge within the MODFLOW domain circulates to the ISS and 27 percent discharges to gaining surface-water bodies. In addition, infiltration to the ISS comes from the following sources: 36 percent from recharge within the model domain, 45 percent from lateral flow into the domain, 15 percent from Lake Michigan, and 4 percent from other surface-water bodies. Particle tracking reveals that the median traveltime from the recharge point to surface-water features is 8 years; the median time to the ISS is 255 years. The traveltimes to the ISS are least over the northern part of the valley, where dolomite is near the land surface. The distribution of traveltimes in the MODFLOW simulation is greatly influenced by the effective porosity values assigned to the various lithologies.

Wisconsin↗

USGS2000

Simulation of the shallow hydrologic system in the vicinity of Middle Genesee Lake, Wisconsin, using analytic elements and parameter estimation

Middle Genesee Lake is a ground-water flow-through lake located in a developing area in southeastern Wisconsin. Because the lake is in good connection with the shallow ground-water system, hydrologic stresses to the shallow ground-water system could adversely affect the lake system. In order to assess the effects of potential stresses on the lake, a study was completed by the U.S. Geological Survey, in cooperation with the Middle Genesee Lake Management District. The objective of the study was to identify areas that contribute ground water to the lake and estimate the hydrologic budget of the lake and hydraulic parameters affecting ground-water flow. A two-dimensional, steady-state analytic element model of the lake and surrounding area was developed using the computer code GFLOW. A parameter estimation model, UCODE, was used to optimize the calibration to measured water levels and streamflow. The calibrated model was used to evaluate the effect of three hypothetical stress scenarios on the stage of Middle Genesee Lake; the simulations were linked to UCODE, which formally incorporated parameter uncertainty into 95-percent confidence intervals around the simulated value. The scenarios included: (1) pumping from upgradient irrigation wells, (2) pumping from Lower Genesee Lake to lower lake levels, and (3) reduction in recharge resulting from development. The results of the simulations demonstrated that lake levels could be affected by hydrologic stresses in the shallow hydrologic system, with effects ranging from a 2.7 feet decline in lake stage resulting from pumping in Lower Genesee Lake to a 0.1 feet decline in lake stage from development in part of the upgradient recharge area. The range of lake stage decline increased when parameter uncertainty was included, from a decline of 3.1 feet for pumping from Lower Genesee Lake to no reduction in lake stage for the development in the recharge area. Whereas these simulated effects are within the natural variation in lake stage, they represent a systematic reduction of ground-water flow to the lake. Therefore, these hypothetical stresses are expected to establish a new, lower, baseline lake stage over which the natural variation due to climatic effects are added and subtracted.

Wisconsin↗

USGS1999

Simulation of stage and hydrologic budget for Shell Lake, Washburn County, Wisconsin

A model that simulates lake stage was developed to test the current understanding of the hydrology of Shell Lake, Wisconsin and to provide a tool for predicting the effects of withdrawing lake water on future lake stages. The model code is written in Fortran and simulates daily lake stage by summing estimates of hydrologic-budget components - precipitation falling on the lake surface, water evaporating from the lake surface, runoff (consisting of overland flow to the lake and intermittent streams flowing into the lake), and ground-water flow out of the lake. The model was calibrated to intermittent lake stage measurements for the period 1948-98. The hydrologic budget model was coupled to UCODE, a parameter estimation model, to aid in estimating runoff coefficients. Trends in stage simulated by the calibrated model compare reasonably well with historical stage trends. The root mean square of the differences of simulated and measured daily lake stage for the period 1948-98 is 0.54 foot. Predictive simulations indicate that withdrawing lake water is an effective way of reducing lake stage. Several years of pumping for at least 200 days per year at rates of 1,000 to 2,000 gallons per minute would have been required to reduce 1990's high stages by about one foot.

Wisconsin↗

USGS1998

Optimization of ground-water withdrawal in the lower Fox River communities, Wisconsin

Pumping from closely spaced wells in the Central Brown County area and the Fox Cities area near the north shore of Lake Winnebago has resulted in the formation of deep cones of depression in the vicinity of the two pumping centers. Water-level measurements indicate there has been a steady decline in water levels in the vicinity of these two pumping centers for the past 50 years. This report describes the use of ground-water optimization modeling to efficiently allocate the ground-water resources in the Lower Fox River Valley. A 3-dimensional ground-water flow model was used along with optimization techniques to determine the optimal withdrawal rates for a variety of management alternatives. The simulations were conducted separately for the Central Brown County area and the Fox Cities area. For all simulations, the objective of the optimization was to maximize total ground-water withdrawals. The results indicate that ground water can supply nearly all of the projected 2030 demand for Central Brown County municipalities if all of the wells are managed (including the city of Green Bay), 8 new wells are installed, and the water-levels are allowed to decline to 100 ft below the bottom of the confining unit. Ground water can supply nearly all of the projected 2030 demand for the Fox Cities if the municipalities in Central Brown County convert to surface water; if Central Brown County municipalities follow the optimized strategy described above, there will be a considerable shortfall of available ground water for the Fox Cities communities. Relaxing the water-level constraint in a few wells, however, would likely result in increased availability of water. In all cases examined, optimization alternatives result in a rebound of the steady-state water levels due to projected 2030 withdrawal rates to levels at or near the bottom of the confining unit, resulting in increased well capacity. Because the simulations are steady-state, if all of the conditions of the model remain the same these withdrawal rates would be sustainable in perpetuity.

Wisconsin↗

USGS1995

Simulation of stage and the the hydrologic budget of Devils Lake, Sauk County, Wisconsin

Water clarity of Devils Lake, in the Driftless Area of southwestern Wisconsin, has been decreasing because of blue-green algal blooms. An understanding of the hydrology of Devils Lake is needed to develop a mitigation plan to reduce phosphorus input. A model was developed to test the current understanding of the hydrology of the lake including stage and hydrologic budget and to estimate the effects of proposed mitigation plans on lake stage. Daily lake stage was simulated in the model by summing estimates of hydrologic-budget components. The Devils Lake hydrologic-budget components are precipitation on the lake surface, evaporation from the lake surface, runoff (consisting of overland flow to the lake and an intermittent stream flowing into the lake), and ground-water flow into and out of the lake. The model was calibrated to measured lake stage for the period 1980-92. Simulated stage compares reasonably well with historical stage data for Devils Lake. The root mean square of the differences of simulated and measured daily lake stages for the period 1980-92 is 0.83 foot. Simulated lake stage is very sensitive to small changes in runoff and evaporation coefficients, and ground-waterflow rates used in the model. The average model-calculated annual amounts of each hydrologic-budget component for the 1980-92 simulation period, in order of increasing volume, are evaporation (791 acre-feet), precipitation (973 acre-feet), runoff (1,107 acre-feet), and net ground-water flow, which is out of the lake (1,323 acre-feet). Three mitigation plans were simulated. Mitigation plan 3, which includes the addition of water from a basin adjacent to the northeastern side of the Devils Lake Basin, allows for withdrawals of hypolimnetic water and maintaining lake stage closer to optimal levels than would result without mitigation.

Wisconsin↗

USGS1994

Water resources of the Menominee Indian Reservation of Wisconsin

Water resources of the Menominee Indian Reservation, Wisconsin, were investigated during the period October 1981 through September 1987. The report presents baseline data and some interpretation of ground- and surface-water hydrology and quality of the Reservation. The area stratigraphy consists of basal Precambrian crystalline bedrock and overlying till and sand and gravel deposits. In the Reservation, the glacial deposits range in thickness from zero to 180 feet. The bedrock aquifer is composed of fractured and weathered Precambrian bedrock within about 20 feet of the upper bedrock surface. The sand and gravel aquifer is composed of saturated, permeable sand and gravel that occurs as layers, lenses, terrace deposits, and valley fillings. The glacial material has a saturated thickness ranging from approximately 150 feet to zero feet in areas where the Precambrian bedrock crops out. Water-table conditions commonly occur in both aquifers. Horizontal hydraulic conductivity of the sand and gravel and bedrock aquifers is estimated to be 5 and 0.3 feet per day, respectively. The Wolf River and its tributaries drain the Reservation except for the eastern quarter, which is drained by the South Branch of the Oconto River. The average discharge of the Wolf River, monitored continuously during 1907-85 at Keshena Falls near Keshena, was 762 ft 3/s (cubic feet per second). Maximum instantaneous discharge was 5,200 ft3/s recorded on March 15, 1973, and the minimum was 91 ft3/s recorded on December 22,1939. Low flow and flood-frequency characteristics for the Wolf River were estimated using mean-daily discharge for the period of record at Keshena Falls. Ground water from the sand and gravel and bedrock aquifers is a calcium magnesium bicarbonate type. The composition of waters from the two aquifers is similar because water recharging the bedrock aquifer is from the overlying sand and gravel aquifer. Iron or manganese concentrations exceeding secondary maximum contaminant levels were found in water samples from approximately one-quarter to one-half of the wells sampled. Approximately three-quarters of the groundwater sampled during the study is moderately hard to very hard, with a median hardness equal to 171 mg/L (milligrams per liter) (as calcium carbonate)for the sand and gravel aquifer and 165mg/L (as calcium carbonate) for the bedrock aquifer. Alkalinity of the ground water ranged from26 to 211 mg/L, with a median value of 182 mg/L(as calcium carbonate) for the sand and gravel aquifer and ranged from 72 to 250 mg/L, with a median value of 170 mg/L (as calcium carbonate)for the bedrock aquifer. Water samples collected from Reservation streams and lakes were similar to ground water (calcium magnesium bicarbonate type), reflecting the strong surface-water/ground-water interaction in the study area. The chemical composition of water from lakes having inlets or outlets indicate that they are not influenced by precipitation as much as lakes that do not have inlets or outlets.

Wisconsin↗

USGS1992

Data on water quality, lake sediment, and lake-level fluctuation, St. Croix Indian Reservation, Wisconsin, 1981-87

This report is a compilation of data on surface- and ground-water quality, lake sediment, and lake-level fluctuation collected by the U.S. Geological Survey (USGS) during 1981- 87 on or near the St. Croix Indian Reservation. The purpose of this report is to provide baseline data on selected aspects of the water resources of the St. Croix Indian Reservation as a referenceby which future hydrologic changes can be discerned. The tribal lands are adjacent to Bashaw, BigRound, Big Sand, Clam, Gaslyn, Rice, and Sand Lakes and the Danbury Settlement along the St. Croix River. Water samples from each of these lakes and Bear Lake, which is not adjacent to tribal land, were analyzed for water-quality indicators. Lakelevel fluctuations also were measured for each lake except Big Round Lake. Grain-size and chemical analyses were done on lake-sediment samples from Bashaw, Rice, Clam, Gaslyn, and Bear Lakes. Ground-water samples from wells on or near tribal land in Burnett County (27 wells) and Polk County (3 wells) were collected and analyzed for water quality.

Wisconsin↗

USGS1987

Prediction of the effects of mine dewatering on four lakes near Crandon, Wisconsin, by use of a water-budget model

The effects of dewatering a proposed zinc and copper mine on water levels of four lakes near Crandon, Wisconsin, were predicted by use of a digital water-budget model of the lakes. The average lake-stage reduction predicted by the model for expected ground-water levels after mine dewatering ranged from 0.21 feet for Duck Lake to 6.9 feet for Little Sand Lake. These stage reductions assume that no water is pumped into the lakes and that no changes are made to the outlet structures. The predicted flow augmentation to the lakes to offset lowering of ground-water levels by mine dewatering range from 8 gallons per minute for Duck Lake to 580 gallons per minute for Little Sand Lake. Because of uncertainty in variables used in the model and in the data used to calibrate the model, the predictions of the model are subject to an undetermined degree of uncertainty.

Wisconsin↗

USGS1987

Estimated use of ground water for irrigation in Wisconsin, 1984

The flow from a sample of 143 irrigation wells from 6 irrigation areas in Wisconsin was measured using an external flowmeter during the 1983-84 irrigation seasons. The measured pumpages were correlated with reported pumpages. The equation that describes this correlation is Q(sub)m = 0.86 x Q(sub)r where Q(sub)m is the measured pumpage and Q(sub)r is the reported pumpage. This equation was used to adjust all reported irrigation pumpage, yielding a more accurate estimate of total irrigation water use. The maximum total irrigation pumpage for 1984 was estimated to be 31,700 million gallons by using the equation and accounting for both reported and unreported pumpage. From 1979 to 1984, irrigation pumpage increased a maximum of 25% and the maximum number of irrigation wells increased 32%. (Author 's abstract)

Wisconsin↗

USGS1986

Hydrogeology and ground-water use and quality, Brown County, Wisconsin

The Paleozoic rock of Brown County includes formations of Cambrian, Ordovician, and Silurian age. These formations are eastward-dipping sedimentary rock that rest on Precambrian crystalline rock and are overlain by Pleistocene deposits. The units that are the principal sources of ground water were grouped into three aquifers (upper, St. Peter, and Elk Mound), and the less permeable units are grouped into three confining units (Maquoketa-Sinnipee, St. Lawrence, and Precambrian). The geologic and hydraulic characteristics of the aquifers and confining units are estimated from logs of more than 1,000 Brown County wells, from results of a packer test, and from published values. Recharge to the water table, which was estimated at five monitored sites, ranges from 1 to 6 inches a year; most recharge is contributed by spring snowmelt and rainfall. A cone of depression caused by pumping the deeper aquifers in the Green Bay metropolitan area induces flow from the upper aquifer to the underlying st. Peter aquifer throughout most of the county. Several reaches of Duck Creek and the Suamico River also contribute water to the aquifers. A bout 13 million gallons per day of ground water was pumped in Brown County during 1979, 63 percent of which was from wells open to both the St. Peter and Elk Mound aquifers. Municipal and industrial water users pumped 9.44 million gallons per day or 72 percent of the ground water withdrawn in 1979. Most ground :water in the county is a calcium magnesium bicarbonate type. However, water from wells sampled in an area between the Fox River and Silurian escarpment have elevated levels of sodium (44 milligrams per liter) and sulfate (226 milligrams per liter). Water from wells that tap rocks older than Silurian dolomite contains high concentrations of strontium (more than 2.4 milligrams per liter) and fluoride (more than 0.85 milligrams per liter). A three-dimensional digital model was used to simulate flow in the ground-water system. Model results indicate that sources of ground water pumped from wells tapping the St. Peter and Elk Mound aquifers in Brown County, 1979, include 4.8 million gallons per day of underflow, most of which enters the county across the west border; 1.9 million gallons per day of flow from vertical leakage within the county; and 1.5 million gallons per day from storage. The model is most sensitive to the horizontal hydraulic conductivity of the upper aquifer. Vertical hydraulic conductivity of the confining units and recharge rates to the water-table aquifer are the least well-defined model parameters.

Wisconsin↗

USGS1984

Water in sand and gravel deposits in McHenry County, Illinois

McHenry County, Illinois derives a major part of its ground-water supply from unconsolidated sand and gravel aquifers. Twenty-six public systems tap these aquifers for all or part of their supply. The county contains two types of sand and gravel aquifers--unconfined aquifers which are at or near the land surface, and semiconfined aquifers which are overlain by one or more till members. A map of water levels in unconfined and semiconfined aquifers shows that moraines and other topographically high features are ground-water divides of local flow systems. Distances from ground-water divides to discharge areas are a few miles or less. The quality of the ground water is good for most uses, although treatment may be required to reduce hardness (median concentration is 340 milligrams per liter) and dissolved iron (median concentrations is 140 micrograms per liter). Ground water is a calcium magnesium bicarbonate type. The range of specific conductance is from 260 to 1,170 micromhos. Values are higher near towns. (USGS)

Water-Resources Investigations Report↗