Geology topics
G. N. Delin
Publications and source records attributed to G. N. Delin.
Geohydrology and water quality of confined-drift aquifers in the Brooten-Belgrade area, west-central Minnesota
Confined-drift aquifers in six aquifer zones identified in a 1,300-square-mile area of west-central Minnesota near Brooten and Belgrade range in thickness from 5 to 110 feet. Transmissivities generally range from 500 to 10,000 feet squared per day, and theoretical well yields generally range from 100 to 900 gallons per minute. Regional ground-water flow in the confined-drift aquifers is to the southeast with local discharge to the East and Middle Branches of the Chippewa River, the North Fork Crow and Sauk Rivers, and to smaller streams, lakes, wetlands, and wells. Water levels near high-capacity pumped wells generally fluctuate 5 to 40 feet annually, compared to annual fluctuations of less than 5 feet in the unconfined aquifer. Water from confined-drift aquifers generally is suitable for most uses. The water is hard to very hard and contains locally elevated concentrations of iron, manganese, and dissolved solids. Results from a ground-water-flow model indicate that increased pumping from confined aquifers in the area would not adversely affect water levels. The addition of 10 to 20 hypothetical wells, pumping 123 to 246 million gallons per year, generally resulted in regional water-level declines of 0.1 to 1.0 feet. Simulations showed that the reduced recharge and increased pumping resulting from a 3-year drought probably would lower water levels between 5 and 10 feet regionally in the confined-drift aquifers and as much as 20 feet locally in the unconfined aquifer. Ground-water discharge to the East Branch Chippewa and North Fork Crow Rivers during the simulated drought would be reduced by 38 percent of 1984 conditions.
Evaluation of availability of water from drift aquifers near the Pomme de Terre and Chippewa rivers, western Minnesota
Ground-water flow in the confined- and unconfined-drift aquifers near Appleton and Benson, Minnesota, was simulated with a three-dimensional finite-difference ground-water-flow model. Model results indicate that 98 percent of the total inflow to the modeled area is from precipitation. Of the total outflow, 38 percent is ground-water discharge to the Pom me de Terre and Chippewa Rivers, 36 percent is evapotranspiration, 17 percent is ground-water pumpage, and 8 percent is ground-water discharge to the Minnesota River. The model was used to simulate the effects of below-normal precipitation (drought) and hypothetical increases in ground-water development. Model results indicate that reduced recharge and increased pumping during a three-year extended drought probably would lower water levels 2 to 6 feet regionally in the surficial aquifer and in the Appleton and Benson-middle aquifers and as much as 11 feet near aquifer boundaries. Ground-water discharge to the Pomme de Terre and Chippewa Rivers in the modeled area probably would be reduced during the simulated drought by 15.2 and 7.4 cubic feet per second, respectively, compared to 1982 conditions. The addition of 30 hypothetical wells in the Benson-middle aquifer near Benson, pumping a total of 810 million gallons per year, resulted in water-level declines of as much as 1.3 and 2.7 feet in the surficial and Benson-middle aquifers, respectively. The addition of 28 hypothetical wells in the Appleton aquifer east and southeast of Appleton, pumping a total of 756 million gallons per year, lowered water levels in the surficial and Appleton confined aquifers as much as 5 feet.
Hydrogeology of confined-drift aquifers near the Pomme de Terre and Chippewa rivers, western Minnesota
Confined-drift aquifers in a 1,380-square-mile area of western Minnesota range in thickness from less than 10 feet to 114 feet. Transmissivities range from less than 1,000 square feet per day to over 16,000 square feet per day and theoretical well yields range from less than 100 gallons per minute to more than 1,800 gallons per minute. Regional ground water flow in the confined-drift aquifers is toward the Minnesota River and locally toward smaller streams, lakes, wetlands, and wells. Water levels near high-capacity pumping wells generally fluctuate 5 to 10 feet annually, compared to annual fluctuations of 2 to 3 feet in the surficial aquifers. Water from confined-drift aquifers generally is suitable for most uses. The water is hard to very hard and contains locally elevated concentrations of some chemical constituents. Dissolved-solids concentrations ranged from about 400 to 1,800 milligrams per liter. A ground-water-flow model indicated that increased pumping from two of the confined aquifers simulated, the Appleton and Benson-middle aquifers, would not adversely affect water levels. The addition of 30 hypothetical wells in the Benson-middle aquifer, pumping a total of approximately 792 million gallons per year, resulted in regional water-level declines of as much as 1.4 and 2.7 feet in the surficial and Benson-middle aquifers, respectively. The addition of 28 hypothetical wells in the Appleton aquifer, pumping a total of approximately 756 million gallons per year, lowered water levels as much as 5 feet in the surficial and Appleton aquifers. Simulations of reduced recharge and increased pumping, which could represent a 3-year drought, probably would lower water levels 2 to 6 feet regionally in the surficial and confined aquifers and as much as 11 feet near aquifer boundaries. Ground-water discharge to the Pomme de Terre and Chippewa Rivers in the southern part of the study area probably would be reduced by approximately 15.2 and 7.4 cubic feet per second, respectively, as a result of the simulated drought. Mean discharge of the Pomme de Terre and Chippewa Rivers is 104 and 267 cubic feet per second, respectively.
Confined-drift aquifers studied near the Pomme de Terre and Chippewa Rivers, west-central Minnesota
No abstract available.