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R. J. Lindgren

Publications and source records attributed to R. J. Lindgren.

12 recordsLinked to original sources
USGS2006

Diffuse-flow conceptualization and simulation of the Edwards aquifer, San Antonio region, Texas

A numerical ground-water-flow model (hereinafter, the conduit-flow Edwards aquifer model) of the karstic Edwards aquifer in south-central Texas was developed for a previous study on the basis of a conceptualization emphasizing conduit development and conduit flow, and included simulating conduits as one-cell-wide, continuously connected features. Uncertainties regarding the degree to which conduits pervade the Edwards aquifer and influence ground-water flow, as well as other uncertainties inherent in simulating conduits, raised the question of whether a model based on the conduit-flow conceptualization was the optimum model for the Edwards aquifer. Accordingly, a model with an alternative hydraulic conductivity distribution without conduits was developed in a study conducted during 2004-05 by the U.S. Geological Survey, in cooperation with the San Antonio Water System. The hydraulic conductivity distribution for the modified Edwards aquifer model (hereinafter, the diffuse-flow Edwards aquifer model), based primarily on a conceptualization in which flow in the aquifer predominantly is through a network of numerous small fractures and openings, includes 38 zones, with hydraulic conductivities ranging from 3 to 50,000 feet per day. Revision of model input data for the diffuse-flow Edwards aquifer model was limited to changes in the simulated hydraulic conductivity distribution. The root-mean-square error for 144 target wells for the calibrated steady-state simulation for the diffuse-flow Edwards aquifer model is 20.9 feet. This error represents about 3 percent of the total head difference across the model area. The simulated springflows for Comal and San Marcos Springs for the calibrated steady-state simulation were within 2.4 and 15 percent of the median springflows for the two springs, respectively. The transient calibration period for the diffuse-flow Edwards aquifer model was 1947-2000, with 648 monthly stress periods, the same as for the conduit-flow Edwards aquifer model. The root-mean-square error for a period of drought (May-November 1956) for the calibrated transient simulation for 171 target wells is 33.4 feet, which represents about 5 percent of the total head difference across the model area. The root-mean-square error for a period of above-normal rainfall (November 1974-July 1975) for the calibrated transient simulation for 169 target wells is 25.8 feet, which represents about 4 percent of the total head difference across the model area. The root-mean-square error ranged from 6.3 to 30.4 feet in 12 target wells with long-term water-level measurements for varying periods during 1947-2000 for the calibrated transient simulation for the diffuse-flow Edwards aquifer model, and these errors represent 5.0 to 31.3 percent of the range in water-level fluctuations of each of those wells. The root-mean-square errors for the five major springs in the San Antonio segment of the aquifer for the calibrated transient simulation, as a percentage of the range of discharge fluctuations measured at the springs, varied from 7.2 percent for San Marcos Springs and 8.1 percent for Comal Springs to 28.8 percent for Leona Springs. The root-mean-square errors for hydraulic heads for the conduit-flow Edwards aquifer model are 27, 76, and 30 percent greater than those for the diffuse-flow Edwards aquifer model for the steady-state, drought, and above-normal rainfall synoptic time periods, respectively. The goodness-of-fit between measured and simulated springflows is similar for Comal, San Marcos, and Leona Springs for the diffuse-flow Edwards aquifer model and the conduit-flow Edwards aquifer model. The root-mean-square errors for Comal and Leona Springs were 15.6 and 21.3 percent less, respectively, whereas the root-mean-square error for San Marcos Springs was 3.3 percent greater for the diffuse-flow Edwards aquifer model compared to the conduit-flow Edwards aquifer model. The root-mean-square errors for San Antonio and San Pedro Springs were appreciably greater, 80.2 and 51.0 percent, respectively, for the diffuse-flow Edwards aquifer model. The simulated water budgets for the diffuse-flow Edwards aquifer model are similar to those for the conduit-flow Edwards aquifer model. Differences in percentage of total sources or discharges for a budget component are 2.0 percent or less for all budget components for the steady-state and transient simulations. The largest difference in terms of the magnitude of water budget components for the transient simulation for 1956 was a decrease of about 10,730 acre-feet per year (about 2 per-cent) in springflow for the diffuse-flow Edwards aquifer model compared to the conduit-flow Edwards aquifer model. This decrease in springflow (a water budget discharge) was largely offset by the decreased net loss of water from storage (a water budget source) of about 10,500 acre-feet per year.

Texas↗
USGS2002

Ground-water resources of the uppermost confined aquifers, southern Wadena County and parts of Ottertail, Todd, and Cass Counties, central Minnesota, 1997–2000

Water managers are concerned about the increase of ground-water withdrawals from high-capacity wells completed in the uppermost confined aquifers in southern Wadena County. The hydrogeologic units of primary interest in the study area are the surficial aquifer, the uppermost confining units, and the uppermost confined aquifers. The surficial aquifer underlies all but portions of the eastern, western, and south-central parts of the study area, and is as much as 70 ft thick. The thickness of the uppermost confined aquifers ranges from 0 to 72 ft. The thickness of the aquifers is greatest in the south-central and west-central parts of the study area, where thicknesses exceed 50 ft. Depth to the top of the uppermost confined aquifers ranges from 23 to 132 ft. The thickness of the uppermost confining units ranges from 4 to 132 ft. The regional direction of flow in the uppermost confined aquifers is to the east, southeast, and southwest toward the Crow Wing River in the eastern part of the study area and toward the Leaf River in the western part. Sources of water to the uppermost confined aquifers are leakage of water through overlying till and clay and ground-water flow from adjoining aquifers outside the study area. Discharge from the uppermost confined aquifers is by withdrawal from wells and to the surficial aquifer in river valleys. The theoretical maximum well yields for the uppermost confined aquifers range from less that 175 gal/min to greater than 2,000 gal/min and are greatest in areas of greatest aquifer thickness and transmissivity. The water budget for the calibrated steady-state simulation indicated that areal recharge to the surficial aquifer is 86.9 percent of the water to the aquifers, with leakage to the uppermost confined aquifers contributing 6.9 percent. The largest discharges from the aquifers are leakage to streams (54.5 percent) and ground-water evapotranspiration (41.4 percent). The simulated transient water budget for 1999 indicated that the principal sources of water to the aquifers were areal recharge to the surficial aquifer and release from storage. The principal discharges were stream-aquifer leakage, addition to storage, and ground-water evapotranspiration. Results of the steady-state simulation with anticipated increases in ground-water withdrawals indicated maximum drawdowns of 0.3 ft in the surficial aquifer and 0.9 ft in the uppermost confined aquifers due to the anticipated increases in ground-water withdrawals. Model results indicate that the anticipated increases in withdrawals during a drought may lower water levels 2 to 4 ft regionally in much of both the surficial and uppermost confined aquifers. Water-level declines in the surficial aquifer of about 6 ft may occur in Wadena and in the central part of the aquifer south of the Leaf River. Results of the transient simulation indicate that the anticipated increases in withdrawals during a drought would increase seasonal declines in the surficial and uppermost confined aquifers less than 1 and 2 ft, respectively. Model results indicate that greater than anticipated increases in withdrawals during periods of normal precipitation will have minimal effects on ground-water levels and streamflow in the area. In the uppermost confined aquifers, for example, water levels may decline an average of 0.13 ft regionally, with maximum declines of 0.8 to 2.1 ft near Wadena and Verndale. Greater than anticipated increases in withdrawals would cause decreases in ground-water discharge to streams of about 1.4 percent (2.5 ft 3 /s) of 1998-99 steady-state conditions.

Minnesota↗
USGS2001

Effects of ground-water withdrawals on flow in the Sauk River Valley Aquifer and on streamflow in the Cold Spring area, Minnesota

The U. S. Geological Survey, in cooperation with the city of Cold Spring, Minnesota conducted a study during 1998-99 to: (1) determine the contributing areas of groundwater flow to high-capacity wells, (2) delineate the 10-, 20-, and 30-year time-of-travel zones to high-capacity wells, and (3) determine changes in streamflow in the Sauk River due to ground-water withdrawals. Surficial aquifers underlie a portion of the uplands in the north-central part of the study area and the Sauk River Valley. The upland surficial aquifer is unconfined, with saturated thicknesses ranging from 6 to 37 feet. The Sauk River Valley aquifer consists of hydraulically connected sand and gravel units: (1) the generally continuous surficial unconfined unit underlying the Sauk River Valley and (2) buried confined units that are overlain by till or lake clays in the upland areas. Maximum saturated thickness of the Sauk River Valley aquifer is about 50 feet. Thicknesses of the buried units are generally 10 to 20 feet. Ground-water flow in the upland surficial aquifer is (1) to the south and southeast toward the margins of the aquifer and (2) toward an unnamed creek valley in the northwestern part of the study area. Ground-water flow in the Sauk River Valley aquifer is from upland areas toward the Sauk River and the connected chain of lakes. Based on hydrograph analysis, ground-water recharge rates to the aquifers during 1999 ranged from 5.3 to 8.6 inches per year, with an average value of 7.0 inches per year. Streamflow measurements indicated net gains of 44.8 and 25.8 cubic feet per second for the Sauk River from Cold Spring to Rockville during October 1998 and August 1999, respectively. In general, the Sauk River probably is a gaining stream in all reaches, except for the reach adjacent to the Gold'n Plump Poultry Processing Plant well field. Ground-water withdrawals from the well field induce infiltration of water from the Sauk River to the underlying aquifer. The measured gains in streamflow for Brewery Creek were 2.75 and 2.25 cubic feet per second during October 1998 and August 1999, respectively. A numerical ground-water-flow model was constructed and calibrated for steady-state conditions. Based on the calibrated model, areal recharge accounts for 51.5 percent of the sources of water to the aquifers in the Cold Spring area and inflow through constant-head boundaries contributes 45.8 percent. The largest discharges from the aquifers are leakage from the Sauk River Valley aquifer to the Sauk River and Brewery Creek (53.7 percent) and outflow through constant-head boundaries (33.1 percent). The simulated contributing areas for selected watersupply wells in the Cold Spring area generally extend to and possibly beyond the model boundaries to the north and to the southeast. The contributing areas for the Gold'n Plump Poultry Processing Plant supply wells extend: (1) to the Sauk River, (2) to the north to and possibly beyond to the northern model boundary, and (3) to the southeast to and possibly beyond the southeastern model boundary. The primary effects of projected increased ground-water withdrawals of 0.23 cubic feet per second (7.5 percent increase) were to: (1) decrease outflow from the Sauk River Valley aquifer through constant-head boundaries and (2) decrease leakage from the valley unit of the Sauk River Valley aquifer to the streams. No appreciable differences were discernible between the simulated steady-state contributing areas to wells with 1998 pumpage and those with the projected pumpage.

Minnesota↗
USGS1997

Hydraulic properties and ground-water flow in the St Peter-Prairie du Chien-Jordan aquifer, Rochester area, southeastern Minnesota

The hydraulic properties were updated and their effects on ground-water flow in the St. Peter-Prairie du Chien-Jordan aquifer in the Rochester area in southeastern Minnesota were evaluated, using new information compiled since a study by Delin (1990). Since 1988, new information on the hydrogeology of the ground-water system in the Rochester area has become available from well-drilling and construction activity associated with Rochester's rapid growth. The St. Peter-Prairie du Chien-Jordan aquifer consists of the St. Peter Sandstone, the Prairie du Chien Group (limestones and dolomites), and the Jordan Sandstone. Horizontal hydraulic conductivity and transmissivity were determined from 15 aquifer tests and specific-capacity information compiled for 310 wells. A 140-square-mile area of the aquifer bounded on the west, south, and east by a ground-water divide contributes water to the Rochester, Minnesota, municipal wells. Transmissivities for the St. Peter-Prairie du Chien-Jordan aquifer in the study area range from less than 5,000 square feet per day (ft 2 /d) to greater than 20,000 ft 2 /d. Transmissivities greater than 20,000 ft 2 /d occur in the west-central, northwestern, and east-central parts of the study area. Transmissivities of less than 5,000 ft 2 /d occur in the northern, northeastern, central, and southern parts of the study area. The areas of greatest potential well yield coincide with areas of greatest transmissivity. Delin (1990) developed a ground-water-flow model to simulate flow of ground water in the St. Peter-Prairie du Chien-Jordan aquifer in the Rochester area. The 1988 Rochester model was rerun using revised horizontal hydraulic conductivity arrays in the model, based on the transmissivity distribution determined for this study. The results of the simulations using horizontal hydraulic conductivities based on the transmissivity distribution determined for this study may indicate that transmissivity values derived from specific-capacity information generally are too high. The transmissivity distribution determined for this study, however, is valid as an indicator of the spatial variability of the relative magnitude of transmissivity and potential well yield for the St. Peter-Prairie du Chien-Jordan aquifer in the study area. Water-level changes in wells from January through February 1988 to February through March 1995 ranged from -6.8 to +15.3 feet. Water-level changes in 12 Rochester municipal wells for the same period ranged from -7.4 to +8.0 feet. Water levels in wells generally rose in the northern and eastern parts of the study area and generally declined in the southwestern and western parts. Near Rochester, water levels in wells generally declined near the city boundaries and showed little change or rose in the central part of the city. Water-level changes from 1988 to 1995 near the ground-water divide generally were less than 2 feet, resulting in no appreciable changes in the location of the divide.

Minnesota↗
USGS1997

Hydrogeology and ground-water quality of confined aquifers in buried valleys in Rock County, Minnesota and Minnehaha County, South Dakota

Confined glacial and bedrock aquifers are present within Quaternary and Cretaceous deposits that fill buried valleys incised in the Sioux Quartzite surface in Rock County, in southwestern Minnesota and Minnehaha County, South Dakota. This report describes the areal extent, thickness, water-bearing characteristics, water-supply potential, and water-quality characteristics of confined aquifers within buriedvalley deposits in Rock County. Hydrogeologic units present within buried-valley deposits in Rock County include unconfined and confined drift aquifers, undifferentiated Cretaceous aquifers, the Split Rock Creek aquifer, and interbedded confining units. The undifferentiated Cretaceous aquifers consist of sandstone layers within interbedded claystone and siltstone overlying the Split Rock Creek Formation or Sioux Quartzite. The Split Rock Creek Formation consisting of sand units (comprising the Split Rock Creek aquifer) and interbedded layers of siltstone and claystone, is present in buried valleys incised in the Sioux Quartzite surface in southern and possibly northeastern Rock County, Minnesota. Confined drift aquifers with thicknesses greater than 5 feet were penetrated in 6 of 10 test holes. Thicknesses of the confined drift aquifers in Rock County range from at least 2 to greater than 32 feet. Estimated horizontal hydraulic conductivity for a confined drift aquifer derived from specific-capacity information from one domestic well log was 73 feet per day. No major (thickness greater than 5 feet) undifferentiated Cretaceous aquifers were penetrated in 10 test holes. Thicknesses of the undifferentiated Cretaceous aquifers compiled from the geologic logs for four domestic wells ranged from at least 7 feet to greater than 46 feet. Estimated horizontal hydraulic conductivity for an undifferentiated Cretaceous aquifer derived from specific-capacity information from one domestic well log was 55 feet per day. Cumulative sand thicknesses for the Split Rock Creek aquifer in 10 test holes ranged from zero to 128.5 feet in 2 to 6 layers. The largest cumulative sand thicknesses were penetrated near the southern margin of the Sioux Quartzite high in northern Rock County and in an east-west trending buried valley (Brandon Embayment) entering Rock County from Minnehaha County, South Dakota. These comparatively large cumulative sand thicknesses are probably due to a high-energy depositional environment. Estimated horizontal hydraulic conductivities for the Split Rock Creek aquifer in Rock County derived from analysis of three slug tests were 0.1, 0.2, and 1 foot per day. The corresponding aquifer transmissivities, calculated as the horizontal hydraulic conductivity multiplied by the cumulative sand thickness, were 3, 16, and 130 feet squared per day. The greatest horizontal hydraulic conductivity and transmissivity estimates were for a site near the southern margin of the Sioux Quartzite high. The watersupply potential of the Split Rock Creek aquifer in Rock County is generally limited by the low transmissivity of the aquifer due to the fineness of the aquifer material (generally very fine- to fine-grained sand). Recharge to the Split Rock Creek aquifer is thought to be derived primarily from hydraulic connection to the Sioux Quartzite aquifer as infiltration of precipitation moves through the fractures and joints of the Sioux Quartzite to the Split Rock Creek aquifer. The regional directions of flow in the aquifer are to the south away from the Sioux Quartzite high and to the west in the Brandon Embayment in Minnehaha County and its east-west trending extension into Rock County. The predominant ions in water from two wells screened in confined drift aquifers in Rock County were calcium and bicarbonate and in water from a third well were calcium and sulfate. The predominant ions in water from one well screened in an undifferentiated Cretaceous aquifer in Rock County were calcium and bicarbonate and in water from a second well were calcium and sulfate. The predominant ions in water from two wells screened in the Split Rock Creek aquifer in Rock County were calcium and bicarbonate and in water from a third well were calcium and sulfate.

Minnesota, South Dakota↗
USGS1996

Availability and quality of water from drift aquifers in Marshall, Pennington, Polk, and Red Lake counties, northwestern Minnesota

Sand and gravel aquifers present within glacial deposits are important sources of water in Marshall, Pennington, Polk, and Red Lake Counties in northwestern Minnesota. Saturated thicknesses of the unconfined aquifers range from 0 to 30 feet. Estimated horizontal hydraulic conductivities range from 2.5 to 600 feet per day. Transmissivity of the unconfined aquifers ranges from 33 to greater than 3,910 feet squared per day. Theoretical maximum well yields for 6 wells with specific-capacity data range from 12 to 123 gallons per minute. Saturated thicknesses of shallow confined aquifers (depth to top of the aquifer less than 100 feet below land surface) range from 0 to 150 feet. Thicknesses of intermediate, deep, and basal confined aquifers (depths to top of the aquifer from 100 to 199 feet, from 200 to 299 feet, and 300 feet or more below land surface, respectively) range from 0 to more than 126 feet. Transmissivity of the confined aquifers ranges from 2 to greater than 210,000 feet squared per day. Theoretical maximum well yields range from 3 to about 2,000 gallons per minute. Recharge to ground water is predominantly from precipitation that percolates downward to the saturated zone. Recharge to unconfined aquifers in the study area ranged from 4.5 to 12.0 inches per year during 1991 and 1992, based on hydrograph analysis. Model simulations done for this study indicate that recharge rates from 8 to 9 inches per year to unconfined aquifers produce the best matches between model-simulated and measured water levels in wells. Discharge from ground water occurs by seepage to streams, lakes and wetlands, ground-water evapotranspiration, and withdrawals through wells. In 1990, total ground-water withdrawals in the study area were 6.0 million gallons per day. All of the withdrawals were from drift aquifers. Numerical models of ground-water flow were constructed to represent two beach-ridge aquifer systems under steady-state conditions. Beach-ridge aquifer systems were simulated in Pennington, Polk, and Red Lake County. Simulated recharge from the infiltration of precipitation accounts for most of the sources of water to the beach-ridge aquifer systems and simulated evapotranspiration accounts for all of the discharge other than ground-water withdrawals. The numerical-model simulations indicate that upward movement of water from underlying confined aquifers to overlying unconfined aquifers is an important component of ground-water flow within the beach-ridge aquifer systems. Simulated long-term, steady-state yields from the unconfined aquifers are generally less than 50 gallons per minute, due to the generally low saturated thickness of the aquifers and the relatively low hydraulic conductivity of the aquifer material. Water from all the drift aquifers in the study area is very hard (more than 180 milligrams per liter of calcium carbonate). The predominant ions in water from the unconfined and shallow confined aquifers were generally calcium and bicarbonate. Water from the intermediate confined aquifers includes a variety of water types, including calcium bicarbonate, calcium sulfate, mixed calcium-sodium bicarbonate, and sodium chloride type waters. Waters from the deep confined aquifers are predominantly calcium bicarbonate, mixed calcium-sodium bicarbonate, and sodium chloride type waters. Mean concentrations of calcium and magnesium generally decreased with depth below land surface. Mean concentrations of sodium and sulfate generally increased with depth. Mean chloride concentrations were greatest for the shallow and deep confined aquifers and least for the unconfined and intermediate confined aquifers. The concentration and percentage (as percent of total cations) of sodium, and concentration of dissolved solids tend to increase from east to west along regional flow paths. Concentrations and percentages (as percent of total anions) of chloride tend to be greater in the western part of the study area than in the eastern part. These trends are probably due to longer residence time of the water in the flow system, and upward leakage of water from the underlying Cretaceous and Paleozoic strata. Waters from the drift aquifers underlying most of the study area generally are suitable for domestic consumption, crop irrigation, and most other uses. Water from 20 wells screened in unconfined and confined aquifers exceeded U.S. Environmental Protection Agency recommended limits for dissolved solids concentrations. Chemical analyses of waters from the unconfined and confined aquifers generally indicated a potentially low sodium hazard and a medium to high salinity hazard for irrigation. Water samples analyzed for nitrate had nitrate concentrations below the reporting limit (0.05 milligrams per liter) in 10 out of 23 wells. Two samples had nitrate concentrations greater than 10 milligrams per liter. Pesticide concentrations in water samples from 17 wells screened in unconfined and shallow confined aquifers were below or only slightly above laboratory reporting limits.

Minnesota↗
USGS1995

Hydrogeology and ground-water flow of the drift and Platteville aquifer system, St. Louis Park, Minnesota

Three aquifers and two confining units have been delineated within the drift underlying the area near the site of a former coal-tar distillation and wood-preserving plant in St. Louis Park, Minnesota. The hydrogeologic units of the drift, in descending order, are the upper drift aquifer, the upper drift confining unit, the middle drift aquifer, the lower drift confining unit. and the lower drift aquifer. A contamination plume consisting of coal-tar derivatives exists in the drift aquifers and in the Platteville aquifer underlying the southern part of the plant site and areas to the south and east of the plant site. The upper drift aquifer has a maximum saturated thickness of about 25 feet. Horizontal hydraulic conductivities of the upper drift aquifer range from less than 1 to about 25 feet per day in peat areas and from about 50 to 400 feet per day in sand and gravel areas. The upper drift confining unit generally is less than 20 feet thick, with a maximum thickness of 62 feet. The saturated thickness of the middle drift aquifer generally is 20 to 30 feet in areas where the aquifer is both overlain and underlain by a confining unit. The horizontal hydraulic conductivity of the middle drift aquifer ranges from about 50 to 500 feet per day. The lower drift confining unit is as much as 50 feet thick. Model-computed vertical hydraulic conductivities for the upper and lower drift confining units ranged from 0.0002 to 5 feet per day. The lower drift aquifer consists of discontinuous sand and gravel deposits overlying Platteville Formation bedrock and has a maximum thickness of 20 feet where it is overlain by the lower drift confining unit. Water in the drift aquifers and in the Platteville aquifer generally flows from the northwest to the southeast under a hydraulic gradient of about 10 feet per mile. The drift confining units and the Glenwood confining unit. when present, control the vertical movement of water through the aquifers. Discontinuities in these confining units greatly influence patterns of ground-water flow. A numerical cross-sectional ground-water-flow model was used to test concepts of flow of ground water through the drift aquifers and the Platteville aquifer. particularly the effects of confining units and bedrock valleys on vertical flow. The model has eight layers representing, in descending order: ( 1) the upper drift aquifer. (2) the upper drift confining unit, (3) the middle drift aquifer, (4) the upper part of the lower drift confining unit, (5) the lower part of the lower drift confining unit and lower drift aquifer, (6) the Platteville aquifer and bedrock valley deposits, (7) the St. Peter aquifer, and (8) the Prairie du Chien-Jordan aquifer. A sensitivity analysis indicated that model-calculated hydraulic heads in the drift aquifers and in the Platteville aquifer were most sensitive to variations in: (1) the horizontal hydraulic conductivities of the middle drift aquifer, (2) the transmissivities of the Platteville and St. Peter aquifers, (3) the vertical hydraulic conductivities of the lower drift confining unit and the drift material filling the bedrock valley, and (4) the vertical hydraulic conductivity of the basal St. Peter confining unit. The model-calculated water budget indicated that recharge from infiltration of precipitation to the upper and middle drift aquifers and the upper drift confining unit accounts for about 41 percent of the total sources of water. The remaining 59 percent is from subsurface inflow from the west (through specified-head cells). About 70 percent of the outflow from the eastern model boundary was simulated as discharge from the model layers representing the Platteville aquifer and bedrock valley deposits and the St. Peter aquifer. The calibrated simulation indicated that about 99 percent of the total leakage of water from the drift aquifers and from the Platteville aquifer to the underlying St. Peter aquifer occurs through areas where the Glenwood confining unit is absent or discontinuous. Hypothetical changes of the hydraulic properties and the extent of confining units were simulated using the calibrated steady-state model. Increasing the vertical hydraulic conductivity of model layer 4, representing the upper part of the lower drift confining unit, by a factor of 100 in the western part of the cross section resulted in decreased model-calculated leakage to the St. Peter aquifer through the bedrock valley represented in the eastern part of the cross-sectional model. A hypothetical extension of vertical hydraulic conductivities representing the Glenwood confining unit along the entire cross-sectional model resulted in a 98 percent reduction in the model-calculated amount of water leaking from the Platteville aquifer and bedrock valley deposits to the underlying St. Peter aquifer. Model simulations indicate that vertical ground-water flow from the drift aquifers and from the Platteville aquifer to underlying bedrock aquifers is greatest through bedrock valleys. The convergence of flow paths near bedrock valleys and the greater volume of water moving through the valleys would likely result in both increased concentrations and greater vertical movement of contaminants in areas underlain by bedrock valleys as compared to areas not underlain by bedrock valleys. Model results also indicate that field measurements of hydraulic head might not help locate discontinuities in confining units and additional test drilling to locate discontinuities might be necessary.

Minnesota↗
USGS1985

Geohydrology of the High Plains Aquifer, western Kansas

The High Plains aquifer underlies 174,050 sq mi of eight states (Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming) and contains approximately 3.3 billion acre-ft of water in storage. Saturated thicknesses within the aquifer are as great as 600 ft near the southern border of southwest Kansas. The aquifer is replenished primarily by infiltration from precipitation. Average precipitation at the Garden City Experiment Station is 18.93 in/yr. Groundwater flow is generally from west to east under unconfined conditions. Hydraulic connection with subcropping consolidated aquifers allows ground water to flow vertically in minor quantities. The aquifer is depleted primarily by irrigation. Hydraulic conductivity estimates from 1,612 lithologic logs had an average value of 75 ft/day, with a standard deviation of 35 ft/day. Specific yields estimated from the same lithologic logs had a mean of 0.17 and a standard deviation of 0.047. Water from the High Plains aquifer in Kansas generally is suitable for human and animal consumption and irrigation of crops. Typically, it is a calcium bicarbonate type water, with concentrations of total dissolved solids ranging from 250 to 500 mg/L. The quality of water in the aquifer deteriorates toward the east due to mixing with recharge water containing dissolved minerals leached from the overlying soil and unsaturated zones and mineralized water from adjacent bedrock units. The simulated water budget for the steady state model of predevelopment (pre-1950) conditions in the High Plains aquifer in northwest Kansas showed that annual recharge to the aquifer from infiltration of precipitation was 87,000 acre-ft/yr and from boundary inflow, 21,000 acre-ft/yr. Annual discharge from the aquifer was 108,000 acre-ft/yr, including 81,000 acre-ft/yr from leakage to streams, 23,000 acre-ft from outflow at the boundaries of the aquifer, and 4,000 acre-ft from municipal and industrial pumpage. (Lantz-PTT)

Water-Resources Investigations Report↗
USGS1985

Projected ground-water development, ground-water levels, and stream-aquifer leakage in the South Fork Solomon River Valley between Webster Reservoir and Waconda Lake, north-central Kansas, 1979-2020

A two-dimensional finite difference computer model was used to project changes in the potentiometric surface, saturated thickness, and stream aquifer leakage in an alluvial aquifer resulting from four instances of projected groundwater development. The alluvial aquifer occurs in the South Fork Solomon River valley between Webster Reservoir and Waconda Lake in north-central Kansas. In the first two projections, pumpage for irrigation was held constant at 1978 rates throughout the projection period (1979-2020). In the second two projections, the 1978 pumpage was progressively increased each yr through 2020. In the second and fourth projections, surface water diversions in the Osborne Irrigation Canal were decreased by 50 %. For the third and fourth projections, each grid-block in the modeled area was classified initially as one of six types according to whether it represented irrigable or nonirrigable land, to its saturated thickness, to its location inside or outside the canal-river area, and to its pumping rate. The projected base-flow rates (leakage from the aquifer to the river) were lower during the irrigation season (June, July, and August) than during the other months of the yr because of the decline in hydraulic head produced by groundwater pumpage. Stream depletion, calculated as a decrease below the average (1970-78) estimated winter base-flow rate of 16.5 cu ft/sec, varied inversely with base flow. For the first two projections, a constant annual cycle of well pumpage and recharge was used throughout the projection period. Aquifer leakage to the river was nearly constant by the mid-to-late 1990's, implying that flow conditions had attained a stabilized annual cycle. The third and fourth projections never attained an annual stabilized cycle because the irrigation pumpage rate was increased each year. By the early 1980's, the hydraulic head had fallen below river stage, reversing the hydraulic gradient at the stream-aquifer interface and resulting in net leakage from the river to the aquifer during the summer months. By the early 1990 's, the projected potentiometric surface of the aquifer was lower than the river stage even during the winter and spring months. (Author 's abstract)

Water-Resources Investigations Report↗
USGS1982

Determination of irrigation pumpage in parts of Kearny and Finney Counties, southwestern Kansas

Irrigation pumpage was determined for parts of Kearny and Finney Counties in Southwestern Kansas using crop-acreage data and consumptive, irrigation-water requirements. Irrigated acreages for 1974-80 were compiled for wheat, grain sorghum, corn, and alfalfa using records from the U.S. Agricultural Stabilization and Conservation Service. Consumptive-irrigation requirements were computed using a soil-moisture model. The model tabulated monthly soil-moisture and crop-water demand for various crops and computed the volume of irrigation water needed to maintain the available moisture at 50% for loamy soils or at 60% for sandy soils. Irrigated acres in the study area increased from 265,000 acres during 1974 to 321,000 acres during 1980. Irrigation pumpage increased from 584,000 acre-feet during 1974 to 738,000 acre-feet during 1980. Decreased consumptive-irrigation requirements during 1979 resulted in a comparatively small irrigation-pumpage estimate of 458,000 acre-feet. (USGS)

Water-Resources Investigations Report↗