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G. N. Delin

Publications and source records attributed to G. N. Delin.

At least 37 records · Page 2Linked to original sources
USGS1997

Water-quality and hydrogeologic data used to evaluate the effects of farming systems on ground-water quality at the Management Systems Evaluation Area near Princeton, Minnesota, 1991-95

The Minnesota Management Systems Evaluation Area (MSEA) project was part of a multi-scale, inter-agency initiative to evaluate the effects of agricultural management systems on water quality in the midwest corn belt. The research area was located in the Anoka Sand Plain about 5 kilometers southwest of Princeton, Minnesota. The ground-water-quality monitoring network within and immediately surrounding the research area consisted of 73 observation wells and 25 multiport wells. The primary objectives of the ground-water monitoring program at the Minnesota MSEA were to: (1) determine the effects of three farming systems on ground-water quality, and (2) understand the processes and factors affecting the loading, transport, and fate of agricultural chemicals in ground water at the site. This report presents well construction, geologic, water-level, chemical application, water-quality, and quality-assurance data used to evaluate the effects of farming systems on ground-water quality during 1991-95.

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USGS1996

Analysis of hydrogeologic properties in the Prairie du Chien-Jordan aquifer, Shakopee Mdewakanton Sioux Community, southeastern Minnesota

The Prairie du Chien-Jordan aquifer is a major source of water for many communities in southeastern Minnesota. The water-supply well for the Shakopee Mdewakanton Sioux Community derives water from the Jordan part of the aquifer. An aquifer test in the Prairie du Chien-Jordan aquifer in the area of the Shakopee Mdewakanton Sioux Community was completed in November 1995. The test consisted of pumping water from a public works well open to the Jordan part of the aquifer and measuring drawdown in this well and two observation wells. This was followed by measuring recovery in the wells after the pumping was terminated. The Neuman (1974) method for unconfined aquifers was used to analyze data collected from the two observation wells during the drawdown and recovery periods, resulting in a range of estimated aquifer hydraulic properties. Aquifer transmissivity ranged from 4,710 to 7,660 ft 2 /d and aquifer storativity ranged from 8.24 x 10 -5 to 1.60 x 10 -4 . These values are generally in close agreement for all four sets of data, given the limitations of the test, indicating that the test results are accurate and representative of the aquifer hydrogeologic properties. The lack of late-time data made it impossible to accurately assess aquifer specific yield.

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USGS1995

Effects of 1992 farming systems on ground-water quality at the management systems evaluation area near Princeton, Minnesota

The Management Systems Evaluation Area (MSEA) program was a multiscale, interagency initiative to evaluate the effects of agricultural systems on water quality in the midwest corn belt. The primary objective of the Minnesota MSEA was to evaluate the effects of ridge-tillage practices in a corn and soybean farming system on ground-water quality. The 65-hectare Minnesota MSEA was located in the Anoka Sand Plain near the town of Princeton, Minnesota. Three fanning systems were evaluated: corn-soybean rotation with ridge-tillage (areas B and D), sweet corn-potato rotation (areas A and C), and field corn in consecutive years (continuous corn; area E). Water samples were collected four different times per year from a network of 22 multiport wells and 29 observation wells installed in the saturated zone beneath and adjacent to the cropped areas. Bromide and chloride were used as tracers of water recharged through the cropped areas during 1992. Bromide applied in May 1992 was first detected above background levels between August 1992 and April 1993. Thus, the time of travel of water and bromide moving through the unsaturated zone during 1992 ranged from 3 to 11 months. Chloride applied to area C (sweet corn) in April 1992 was first detected above the residual levels of 1991 chloride applications in April 1993, 12 months after the chemical was applied. Chloride applies to areas A, B, D, and E in April 1992 was not detected above the residual effects from 1991 chloride applications. Nitrogen (N) fertilizer applied in 1992 on area C (potatoes) was first detected above background concentrations and the residual effects of the 1991 farming practices in April 1993, 12 months after application. Effects of 1992 N fertilizer applications on area E (continuous com) generally could not be distinguished from the effects of downgradient of area E were consistently greater than background concentrations during August 1992 through April 1993. These concentrations greater than background levels indicate that some N fertilizer applied to the continuous com crop during 1991 reached the water table. Nitrogen fertilizer applied on areas A, B, and D during 1992 could not be distinguished from the residual effects of the 1991 fanning practices but were detected above background concentrations. Atrazine concentrations beneath the cropped areas were generally indistinguishable from background concentrations. Atrazine was detected in 58 percent of the 361 ground water samples collected beneath cropped and buffer areas during June 1992 through April 1993. Most detections were at trace levels, between the detection limit of 0.01 micrograms per liter ( μ g/L) and the reporting limit of 0.04 μ g/L. De-ethylatrazine (DEA) was detected more frequently during June 1992 through April 1993 (78 percent of the 361 samples) and in greater concentrations than any other herbicide or herbicide metabolite, with a median concentration of 0.07 μ g/L. The maximum DEA concentration of 0.77 μ g/L was detected near the water table in the middle of area E (continuous corn) during April 1993. The likely source of this DEA detection was application of atrazine to area E during 1991-93. Additional data will be needed to conclusively evaluate whether atrazine applied as part of the MSEA farming systems reached the water table. Results indicate that the effects of the 1992 potassium-chloride and N fertilizer applications were reduced compared to the effects of 1991 applications. The most important factors associated with these differences were lower chemical application rates and lower recharge rates during 1992 than during 1991. Some of the chloride and N fertilizer applied to the cropped areas in 1992 likely did not reach the saturated zone in 1993 due to a 60-percent reduction in recharge compared to 1991. Therefore, analysis of data from additional years will be required to fully evaluate the effects of the fanning systems on ground-water quality.

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USGS1994

Hydrogeologic and water-quality data used to characterize the Management Systems Evaluation Area near Princeton, Minnesota, 1991

The Minnesota Management Systems Evaluation Area project is part of a multi-scale, inter-agency initiative to evaluate the effects of agricultural management systems on water quality in the midwest corn belt. The research area is located in the Anoka Sand Plain about 5 kilometers southwest of Princeton, Minnesota. The ground-water-quality monitoring network within and immediately surrounding the research area consists of 29 observation wells and 22 multiport wells. Thirteen observation wells are also located outside the research area. The primary objectives of research by the U.S. Geological Survey at the Princeton Management Systems Evaluation Area are to: (1) determine the relation of the spatial and temporal distribution of agricultural chemicals in ground water to recharge, topography, and subsurface heterogeneities; and (2) determine the effects of the modified and prevailing farming systems on ground-water quality. This report presents geologic logs and water-quality data used to characterize the Princeton Management Systems Evaluation Area.

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USGS1994

Characterization of the hydrogeology and water quality at the Management Systems Evaluation Area near Princeton, Minnesota, 1991-92

The Management Systems Evaluation Area (MSEA) program is part of a multi-scale, inter-agency initiative to evaluate the effects of agricultural management systems on water quality in the midwest corn belt. The Minnesota MSEA project is one of five projects selected to represent the principal hydrogeologic settings and geographic diversity of prevailing management systems in the midwest corn belt. The Minnesota MSEA research area is located in the Anoka Sand Plain about 5 kilometers southwest of Princeton, Minnesota. The water-quality monitoring network within the 65-hectare research area consists of 29 observation wells and 22 multiport wells. Thirteen observation wells also are located outside the research area. Glacial deposits beneath the research area generally consist of fine to medium sand in the unsaturated zone and coarse to very coarse sand and gravel in the saturated zone. The average depth to the water table is about 3.6 meters below land surface. Ground-water recharge during 1992 was lower (4.9-13.2 centimeters) than during 1991 (11.7-25.7 centimeters) because of reduced precipitation (58.5 centimeters during 1992 and 94.5 centimeters during 1991). Estimates of saturated horizontal hydraulic conductivity for the surficial aquifer were made using five methods. Results were within about two orders of magnitude and also agree favorably with estimates from a previous study of the Anoka Sand Plain. The smallest hydraulic conductivities were obtained using laboratory analyses (0.0052 centimeters per second) and the largest estimate was obtained from results of an aquifer test (0.2820 centimeters per second). The estimate of hydraulic conductivity based on the time of travel of chloride (0.0655 centimeters per second) is considered most accurate and representative of the surficial aquifer in the research area. Anthropogenic effects of previous land use were detected in water samples collected during April 1991, prior to implementation of the MSEA farming systems. Concentrations of nitrate-nitrogen (nitrate-N) in the surficial aquifer equaled or exceeded the U.S. Environmental Protection Agency's recommended maximum contaminant level of 10 milligrams per liter (mg/L) in 4 of the 7 wells in the research area. The maximum concentration of nitrate-N in ground water from these wells was 23 mg/L with a median of 10 mg/L. The median concentration of nitrate-N for these wells exceeded the median in wells located upgradient from the research area (2.1 mg/L). Similarly, the median concentration of chloride from wells in the research area (11 mg/L) exceeded the median in upgradient wells (3.8 mg/L). On-site sources of the elevated nitrate-N include decomposition of alfalfa, grown on-site during 1981-89, and application of nitrogen fertilizer to corn during 1990. A likely on-site source of the elevated chloride is application of potassium-chloride fertilizer to crops prior to 1991. Atrazine was detected by gas chromatography mass spectroscopy in 2 of the 7 wells in the research area at concentrations of 0.04 and 0.17 micrograms per liter (ug/L), well below the U.S. Environmental Protection Agency's recommended maximum contaminant level of 3 ug/L. The median concentration in these Wells was less than the qualitative detection limit of 0.01 ug/L. Atrazine metabolite de-ethylatrazine was the most frequently detected herbicide or herbicide metabolite. De-ethylatrazine was detected in 5 of the 7 wells in the research area at concentrations ranging from 0.12 to 0.32 ug/L with a median concentration of 0.14 ug/L. Atrazine metabolite de-isopropylatrazine was not detected above the qualitative detection limit of 0.06 ug/L. The most likely sources of atrazine are applications to the research area during 1990 or from precipitation.

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USGS1993

Effects of focused recharge on the transport of agricultural chemicals at the Princeton, Minnesota Management Systems Evaluation Area, 1991-92

Rates of water movement through the unsaturated zone greatly affect the amount and concentrations of agricultural chemicals that may reach the water table. For example, recharge can flush chemicals to the water table which have accumulated in the unsaturated zone during dry periods. A better understanding of how topography influences recharge and the movement of agricultural chemicals is needed. In 1991, the U.S. Geological Survey (USGS), with funding from the USGS Toxic Substances Hydrology Program, began studying the movement of water and agricultural chemicals to the water table at the Management Systems Evaluation Area (MSEA) near Princeton, Minnesota. The primary objective of this four-year research study is to evaluate the effects of transient recharge, topography, and subsurface heterogeneities on the flux of water and agricultural chemicals to ground water. To achieve this objective the approach was to (1) install instruments to sample and measure the movement of water through the unsaturated zone beneath topographically high and low areas of a corn field; (2) conduct recharge and tracer tests in the field to evaluate the movement of water and agricultural chemicals at both topographic settings; and (3) simulate the field recharge and tracer tests in the laboratory. The primary research hypothesis was that the vertical flux of water and agricultural chemicals is greater in topographically low areas than in topographically high areas.

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USGS1993

Effects of recharge on the transport of agricultural chemicals at the Princeton, Minn. Management Systems Evaluation Area (MSEA), 1991-92

Rates of water movement through the unsaturated zone greatly affect the amount and concentrations of agricultural chemicals that may reach the water table. For example, recharge can flush to the water table chemicals that have accumulated In the unsaturated zone during dry periods. A better understanding of how topography influences recharge and the movement of agricultural chemicals is needed. In 1991, the U.S. Geological Survey (USGS), with funding from the USGS Toxic Substances Hydrology Program, began studying the movement of water and agricultural chemicals to the water table at the Management Systems Evaluation Area (MSEA) near Princeton, Minnesota. Instruments were installed to measure the movement of moisture through the soil beneath a corn field. Samples of the recharge water were analyzed for concentrations of agricultural chemicals and tracers. Field recharge and tracer tests were simulated In the laboratory.

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USGS1993

Delineation of recharge areas for selected wells in the St. Peter-Prairie du Chien-Jordan aquifer, Rochester, Minnesota

Accurate delineation of recharge areas for wells is an important requisite to protecting ground-water quality. Zones of transport and zones of contribution are two types of recharge areas that can be delineated. Analytical-calculation, numerical-modeling, and hydrogeologic-mapping methods were used to delineate recharge areas for two high-capacity wells (greater than about 200 gallons per minute discharge) completed in a karstic aquifer in the city of Rochester, in southeastern Minnesota. One well is less than 1,000 feet from a river in an area where the aquifer is unconfined, whereas the other well is more than 2,000 feet from a stream in an area where a bedrock confining unit is present. Ground-water travel times from points along the top of the aquifer to a pumped well are identified by use of a constructed map showing lines of equal advective travel time. A zone of transport, therefore, is defined by the area bounded by lines of equal travel time. Zones of transport are delineated by analytical models (calculations) and by numerical models that account for hydrologic factors. Analytical models that were used include fixed-radius (Theis drawdown, Theis time-of-travel, and volumetric equation) and variable shape. Numerical modeling was done with the U.S. Geological Survey three-dimensional ground-water-flow model MODFLOW and particle-tracking code MODPATH. The zone-of-transport areas for each of the two wells calculated by the various analytical models were very similar. The Theis-drawdown method yielded results that compared least favorably with results from the other analytical methods. The zone-of-transport areas computed by use of the numerical model were generally larger than areas computed by use of analytical models. Hydrogeologic mapping and numerical modeling were used to delineate zones of contribution to wells, defined as all parts of a ground-water-flow system that could supply water to a well. The zones of contribution delineated by use of numerical modeling have similar orientation (parallel to regional flow directions) but significantly different areas than the zones of contribution delineated by use of hydrogeologic mapping. Differences in computed areas of recharge are attributed to the capability of the numerical model to more accurately represent (1) the three-dimensional flow system, (2) hydrologic boundaries such as streams, (3) variable recharge, and (4) the influence of nearby pumped wells, compared to the analytical models.

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USGS1992

Hydrologic research at the Princeton, Minnesota management systems evaluation area

The Management Systems Evaluation Area (MSEA) program is part of a multi-scale, inter-agency initiative to evaluate the effects of agricultural management systems on water quality. The program resulted from the integration of the U.S. Department of Agriculture (USDA) Research Plan for Water Quality and the U.S Geological Survey (USGS) Mid-Continent Herbicide Initiative and is part of the President's Water Quality Initiative. The mid-continental corn belt was selected for study because it is an area where about 60% of the Nation's pesticides and nitrogen fertilizers are used.

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USGS1991

Simulation of effects of ground-water development on water-levels in glacial-drift aquifers in the Brooten-Belgrade area, west-central Minnesota

Ground-water flow in the confined- and unconfined-drift aquifers in the Brooten-Belgrade area of west-central Minnesota was simulated with a three-dimensional finite-difference ground-water-flow model. Model results indicate that about 96 percent of the total inflow to the modeled area is from precipitation. Discounting evapotranspiration, 63 percent of the total outflow is ground-water discharge to the East Branch Chippewa and North Fork Crow Rivers, and 34 percent is ground-water pumpage. The model was used to simulate the steady-state effects of below-normal precipitation (drought) and hypothetical increases in ground-water development. Model results indicate that reduced recharge and increased pumping during a hypothetical 3-year extended drought would lower regional water levels from 2 to 5 feet in each aquifer and as much as 20 feet in the lowermost aquifer zone; ground-water discharge to the East Branch Chippewa and North Fork Crow Rivers would be reduced by 38 percent. The addition of 10 to 20 hypothetical wells in confined aquifers, pumping 123 to 246 million gallons per year, would result in regional water-level declines of 0.1 to 0.5 feet. Simulated water-level declines in wells completed in the lower part of the system would be as much as 5.0 feet as a result of pumping 246 million gallons per year from 20 hypothetical wells. Water-level declines in overlying and underlying aquifers would range from 0.4 to 2.8 feet. Ground-water discharge to the East Branch Chippewa and North Fork Crow Rivers would be unaffected by the pumpage.

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USGS1991

Hydrogeology and simulation of ground-water flow in the Rochester area, southeastern Minnesota, 1987-88

Ground-water flow in the St. Peter-Prairie du Chien-Jordan aquifer was studied in a 700 square-mile area surrounding Rochester, Minnesota. The aquifer consisting of sandstone, limestone, and dolomite is locally confined by the Decorah-Platteville-Glenwood sequence of shales and limestones. Regional flow in the aquifer is from a ground-water divide on the western, southern, and eastern sides of the city toward various rivers. A 140-square-mile area of the aquifer is a source of water supply for the Rochester area. A cone of depression in the potentiometric surface of the aquifer throughout most of the year is centered around high-capacity (greater than about 200 gallons per minute) wells in downtown Rochester. The cone covered an area of about 2.3 square miles in August 1988. Most streams in the area gain water from the ground-water system. One reach of the South Fork Zumbro River, however, loses water to the system. This loss is probably caused by the pumping of nearby high-capacity wells. A ground-water-flow model was used to simulate the effects of an extended drought near Rochester. Conclusions based on the simulations are that (1) reduced recharge and increased pumping, conditions that could exist during a 3-year drought, would probably lower water levels 5 to 10 feet regionally and more than 30 feet in the city; (2) pumping of six additional municipal wells on the perimeter of the city would lower regional water levels about 1 to 5 feet; and (3) that water levels would recover 1 to 18 feet if pumping from six municipal wells in downtown Rochester were discontinued. The area encompasses five recharge zones that can be delineated on the basis of recharge rate. About 54 percent of recharge to the aquifer in the area contributing water to Rochester is from a zone along the edge of the Decorah-Platteville-Glenwood confining unit. About 10 percent of recharge in this contributing area is to the sewered area of Rochester.

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