Geology topics
Publications and source records attributed to D. C. Gillies.
As the Nation's principal earth-science information agency, the U.S. Geological Survey (USGS) is depended upon to collect data of the highest quality. This document provides the framework for collecting, analyzing and reporting ground-water data that are quality assured and quality controlled.
The surf icial sands in the Pomme de Terre and Chippewa River valleys in Grant, Pope, Stevens, and Swift Counties have been studied to determine the occurrence, availability, and quality of ground water in these aquifers. In the northern part of the Pomme de Terre and Chippewa River valleys, the aquifers consist of coarse sand and gravel ranging from 0 to 100 feet in thickness; transmissivities range from 0 to 35,000 feet squared per day in narrow, steep-sided erosional valleys. In the north, well yields commonly exceed 1,000 gallons per minute and may be as much as 4,000 gallons per minute locally. Farther south, the deposits are medium to fine grained, range from 0 to 90 feet thick, and reach a maximum width of 10 miles near Benson, Minnesota. Transmissivities range from 0 to 25,000 feet squared per day. Wells may yield as much as 1,500 gallons per minute locally. Southeast of Clontarf, well yields generally do not exceed 500 gallons per minute because the deposits are thinly saturated and fine grained. Ground water in the surf icial aquifer is a mixed calcium magnesium-sulf ate bicarbonate type that is chemically suitable for most uses. Concentrations of most constituents analyzed were below limits recommended by the Minnesota Pollution Control Agency for drinking water, but concentrations of manganese, iron, nitrite plus nitrate, and dissolved solids exceed recommended limits locally. Salinity, as indicated by the specific conductance (values ranged from 580 to 1,000 micromhos per centimeter) was in the medium to high range at several locations. An analytical model was used to estimate the effect on streamflow of pumpage from the surficial aquifer in the narrow, 50-mile reach of the Pomme de Terre River valley in Stevens and Grant Counties. The model indicates that the 43 existing wells pumping at maximum potential yields could reduce streamflow by 55 cubic feet per second. Addition of 23 wells also pumping at maximum potential yields could reduce streamflow by 77 cubic feet per second; this rate exceeds low base flow of the Pomme de Terre River. Finite-difference models were used to simulate flow in the surficial aquifer along the Pomme de Terre River near Appleton in Swift County and along the Chippewa River between Cyrus in Pope County and Danvers in Swift County. In the Appleton area/ model analyses indicate that pumping lowered water levels as much as 3 feet from 1973-80 and reduced streamflow by about 14 cubic feet per second. Additional regional water-level declines of 1 to 2 feet/ and up to 4 feet locally near aquifer-till boundaries, can be expected after about 4 years if pumping continues at the 1980 rate and area! recharge from precipitation is near normal. However/ simulation of increased pumping rates and decreased area! recharge during a 3-year drought indicates that water levels may decline as much as 9 feet near aquifer-till boundaries and streamflow may be reduced by about 41 cubic feet per second, which is about 95 percent of the available flow in the Pomme de Terre River at the 55-percent flow duration. Model results also suggest that/ during the first year of a drought/ the combined pumpage from wells operated during 1980 along the Pomme de Terre River in Stevens and Grant Counties and in the Appleton area could reduce streamflow to zero during base flow. Model-computed streamflow deficiencies are 48 and 60 cubic feet per second at the 55- and 70-percent flow duration/ respectively. Under such conditions/ pumping could not be sustained at the rates simulated unless there was sufficient water stored in the stream channel or streamflow was augmented. In the Cyrus-Benson area/ model results indicate that tinder 1980 development and average area! recharge/ dynamic equilibrium would be reached in less than 4 years and additional drawdown would be less than 2 feet. A 3-year drought coupled with increased pumping from irrigation wells operated during 1980 would lower water levels as much as 6 feet and reduce flow in the Chippewa River by about 26 cubic feet per second. At maximum hypothetical development in terms of the number of wells and normal area! recharge/ water levels would be lowered as much as 9 feet and streamflow would be reduced about 12 cubic feet per second. At maximum hypothetical development/ drought conditions and increased pumping would lower water levels as much as 12 feet and reduce flow in the Chippewa River by about 30 cubic feet per second/ which equals about 75 percent of available streamflow at the 70-percent flow duration.
A study of the hydraulic characteristics of the unconsolidated glacial deposits near the city of Carmel in central Indiana shows that 21.3 million gallons per day (933 litres per second) of additional water could be withdrawn from the aquifer for an indefinite period of time . This pumpage is approximately 5 million gallons per day (219 litres per second) above the projected water needs of Carmel for 1990. Saturated thickness, transmissivity , and storage coefficient of the outwash aquifer along the White River east of Carmel were determined , using available data supplemented by test drilling. The saturated thickness of the aquifer ranges from 10 to 110 feet (3 to 34 metres); transmissivity ranges from 1 , 000 feet squared per day (93 metres squared per day) to 24,000 feet squared per day (2,230 metres squared per day); and the average storage coefficient is 0 . 11. Seepage from the aquifer into the White River was estimated in November 1974, using data from u.S. Geological Survey gaging stations. Water- level information was obtained from a network of observation wells at that same time. Flow in the unconsolidated glacial deposits near the city of Carmel in central Indiana was simulated by a digital-computer model in a study of hydraulic characteristics of the deposits. The study shows that 21.3 million gallons per day (933 litres per second) of additional water could be withdrawn from the aquifer for an indefinite period of time. This pumpage is approximately 5 million gallons per day (219 1itres per second) above the projected water needs of Carmel for 1990. Saturated thickness, transmissivity, and storage coefficient of the outwash aquifer along the White River east of Carmel were determined, using available data supplemented by test drilling . The saturated thickness of the aquifer ranges f r om 10 to 110 feet 0 to 34 me tres); transmissivity ranges from 1,000 feet squared per day (93 metres squared per day) to 24 ,000 feet squared per day (2 ,230 metres squared per day); and the average storage coefficient is 0.11.
County constitute the most extensive aquifers in the county. Four areally distinct sand and gravel aquifers were mapped in the drift during the course of this study. The aquifer of greatest economic importance consists of sand and gravel deposits of glacial-outwash origin which coincide with the courses of the White River and Fall Creek. Ground water in this aquifer is generally unconfined. Three thin, areally discontinuous, sheetlike deposits of sand and gravel situated one above the other occur in the till-plain area of the county. These deposits coalesce in some areas, but generally are separated by beds of silt and clay of varying thickness which cause the ground water in the till-plain aquifers to be semiconfined. The uppermost 100 feet (30 metres) or so of limestone and (or) dolomite underlying the glacial drift constitutes an aquifer of secondary importance in the county. This aquifer is separated from the unconsolidated aquifers either by silt and clay or by shale. The present movement of ground water through these aquifers is generally toward the White River, Fall Creek, Eagle Creek or Buck Creek. Based on seepage data, water levels in the aquifers in April and May 1974, and subsequent electric-analog-model analysis, discharge of ground water by seepage into the streams in the glacial outwash averages about 42 cubic feet per day per foot (3.9 cubic metres per day per metre) of channel length. A four-layer electric-analog model incorporating the geometry and hydraulic characteristics of the aquifers, the confining beds and the stream- aquifer connection was constructed to determine the feasibility and hydrologic results of proposed plans for future ground-water development. Three large well fields were simulated in the model of the glacial-outwash aquifer, with pumping nodes situated so as to take advantage both of high transmissivity areas in the aquifer, and of recharge from the streams. A series of model experiments were carried out to test the capacity of the aquifers to sustain increases in pumpage. In all of these, a new equilibrium was established within 6 years of simulated pumpage. In two of these experiments, water levels in the discharging wells were allowed to draw down to approximately half of the saturated thickness of the glacial-outwash aquifer. At this drawdown limit, the total discharge of wells in the system was found to be 59 million gallons per day (2.6 cubic second) assuming that the streams were fully connected to the upper third of the glacial-outwash aquifer. In two other experiments, discharging wells were allowed to drawdown an average of two-thirds of the saturated thickness of the glacial-outwash aquifer. At this limit, the total discharge was found to be 72 million gallons per day (3.2 cubic metres per second) using the conservative stream-aquifer connection, and 103 million gallons per day (4.5 cubic metres per second) assuming a full connection. Some dewatering of the aquifer was associated with the 72 million gallons per day (3.2 cubic metres per second) discharge. In all experiments, the amount that could be pumped from the confined aquifers without disturbing existing domestic wells was found to be small.