Geology topics
Publications and source records attributed to D. J. Ackerman.
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Ground-water flow simulation indicates that pumpage from the aquifer since the early 1900's has caused a decrease in ground-water outflow to rivers, an increase in flow from rivers into the aquifer, and an increase in flow to the aquifer through the overlying confining unit. By the mid-1970's, rivers became a source of more than 30 percent of total flow into the aquifer rather than the sink of net outflow, and by 1982 inflow through the overlying confining unit increased about 60 percent. Areas with the greatest potential for additional pumpage are northwestern Mississippi and northern parts of the area east of Crowleys Ridge.
Quantitative estimates of ground-water flow directions and traveltimes for advective flow were developed for the regional aquifer system of the eastern Snake River Plain, Idaho. The work included: (1) descriptions of compartments in the aquifer that function as intermediate and regional flow systems, (2) descriptions of pathlines for flow originating at or near the water table, and (3) quantitative estimates of traveltimes for advective transport originating at or near the water table. A particle-tracking postprocessing program was used to compute pathlines on the basis of output from an existing three-dimensional steady-state flow model. The flow model uses 1980 conditions to approximate average annual conditions for 1950-80. The advective transport model required additional information about the nature of flow across model boundaries, aquifer thickness, and porosity. Porosity of two types of basalt strata has been reported for more than 1,500 individual cores from test holes, wells, and outcrops near the south side of the Idaho National Engineering Laboratory. The central 80 percent of samples had porosities of 0.08 to 0.25, the central 50 percent of samples, O. 11 to 0.21. Calibration of the model involved choosing a value for porosity that yielded the best solution. Two radiologic contaminants, iodine-129 and tritium, both introduced to the flow system about 40 years ago, are relatively conservative tracers. Iodine- 129 was considered to be more useful because of a lower analytical detection limit, longer half-life, and longer flow path. The calibration value for porosity was 0.21. Most flow in the aquifer is contained within a regional-scale compartment and follows paths that discharge to the Snake River downstream from Milner Dam. Two intermediate-scale compartments exist along the southeast side of the aquifer and near Mud Lake.One intermediate-scale compartment along the southeast side of the aquifer discharges to the Snake River near American Fails Reservoir and covers an area of nearly 1,000 square miles. This compartment, which receives recharge from an area of intensive surface-water irrigation, is apparently fairly stable. The other intermediate-scale compartment near Mud Lake covers an area of 300 square miles. The stability and size of this compartment are uncertain, but are assumed to be in a state of change. Traveltimes for advective flow from the water table to discharge points in the regional compartment ranged from 12 to 350 years for 80 percent of the particles; in the intermediate-scale flow compartment near American Falls Reservoir, from 7 to 60 years for 80 percent of the particles; and in the intermediate-scale compartment near Mud Lake, from 25 to 100 years for 80 percent of the particles. Traveltimes are sensitive to porosity and assumptions regarding the importance of the strength of internal sinks, which represent ground-water pumpage. A decrease in porosity results in shorter traveltimes but not a uniform decrease in traveltime, because the porosity and thickness is different in each model layer. Most flow was horizontal and occurred in the top 500 feet of the aquifer. An important limitation of the model is the assumption of steady-state flow. The most recent trend in the flow system has been a decrease in recharge since 1987 because of an extended drought and changes in land use. A decrease in flow through the system will result in longer traveltimes than those predicted for a greater flow. Because the interpretation of the model was limited to flow on a larger scale, and did not consider individual wells or well fields, the interpretations were not seriously limited by the discretization of well discharge. The interpretations made from this model also were limited by the discretization of the major discharge areas. Near discharge areas, pathlines might not be representative at the resolution of the grid. Most improvement in the estimates of ground-waterflow directions and travelt
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Maps that show contours of the altitude of water levels for wells completed in the Mississippi River Valley alluvial aquifer in eastern Arkansas were prepared using water-level measurements made in the spring of 1972-1980. Hydrographs for selected wells are included to show trends and lack of trends in water-level changes. The aquifer consists of gravel and sand in flood-plain and terrace deposits of Quaternary age. The aquifer supplies much of the water used for irrigation and aquaculture in eastern Arkansas. A large depression in the potentiometric surface caused by pumping for irrigation and aquaculture occurs in Arkansas, Lonoke, and Prairie Counties. A smaller depression in the potentiometric surface occurs north of Brinkley. Significant water-level declines occurred during the period 1972-80 in several counties west of Crowleys Ridge. (USGS)
This map shows the generalized contours of the altitude of water levels in wells completed in the Cockfield Formation in southeastern Arkansas for 1980. Most water levels used in constructing the map were made in the spring of 1980. However, in parts of the State water levels from the spring of 1980 were unavailable. Where data indicated no long-term changes in nearby water levels, measurements from as early as 1952 and as late as 1983 were used. At a few locations the altitude of the water surface in a stream was used to define the potentiometric surface. Available water level data limited the interpretation of potentiometric surface primarily to the area of occurrence of the aquifers south of the Arkansas River. Water level data from Arkansas and adjacent states used in the construction of this map are from the groundwater file of the U.S. Geological Survey 's National Water Data Storage and Retrieval System. This map was prepared as part of the Gulf Coast Regional Aquifer-System Analysis study.
A map shows generalized contours of the altitude of water levels for wells completed in the Sparta-Memphis aquifer in eastern Arkansas. Most water-level measurements used in constructing the map were from the spring of 1980, but supplemental measurements from other years indicated no long-term change in water levels. Hydrographs for selected wells are included to show trends and lack of trends in water-level changes. The aquifer in the Sparta Sand and Memphis Sand of Eocene age which consists of fine to medium sand interbedded with salt, clay, and lignite. The aquifer supplies much of the water used for industry and public supply for eastern Arkansas. Some irrigation users also obtain supplies from the aquifer. Cones of depression caused by pumpage for industrial and public supplies occur near Camden, El Dorado, Magnolia, Pine Buff, and West Memphis.
Hydrologic data were collected from 36 wells and 80 springs in the San Miguel River basin from 1977 to 1979. Depth to water was measured for 22 wells and discharges were measured for 53 springs. Chemical analyses for water samples collected from 23 wells and 25 springs indicated larger dissolved solids concentrations in bedrock water samples than in alluvial water samples. Drillers ' records obtained from the Colorado State Engineer 's Office for 86 wells indicate generally larger yields from wells completed in alluvium than in bedrock. (USGS)
Information about ground-water quantity and quality in the lower Gunnison River basin assists in developing, appropriating, and managing the basin 's water resources. Hydrogeologic data are presented for 51 wells and 61 springs. Chemical analyses are given for 34 wells and 17 springs. Drillers ' reports for 71 wells are included. Springs normally discharge from short alluvial flow systems and commonly are less saline than well water. These springs are a calcium magnesium bicarbonate water type. Spring discharges of as much as 200 gallons per minute were measured. The most productive wells in the study area are completed in alluvium, with reported yields of as much as 750 gallons per minute for an irrigation well. Alluvial gravels are most productive. Specific-conductance values of water samples from alluvial deposits ranged from 80 to 32,200 micromhos per centimeter at 25 Celsius. The Mancos Shale and Mesaverde Formation include aquifers with large areal extents. Reported yields of wells completed in the Mesaverde Formation range from 0.7 to 24 gallons per minute. The Dakota Sandstone, Morrison Formation, and Entrada Sandstone include potential aquifers of lesser extent. Reported yields of wells completed in the Dakota Sandstone range 5 to 14 gallons per minute in the study area. Specific-conductance values of water samples from the Mesaverde Formation ranged from 325 to 5,390 micromhos per centimeter at 25 Celsius. Insufficient data prevented water-quality analysis of other rock units. (USGS)
The San Miguel River Basin encompasses 4,130 square kilometers of which about two-thirds is in the southeastern part of the Paradox Basin. The Paradox Basin is a part of the Colorado Plateaus that is underlain by a thick sequence of evaporite beds of Pennsylvanian age. The rock units that underlie the area have been grouped into hydrogeologic units based on their water-transmitting ability. Evaporite beds of mostly salt are both overlain and underlain by confining beds. Aquifers are present above and below the confining-bed sequence. The principal element of ground-water outflow from the upper aquifer is flow to the San Miguel River and its tributaries; this averages about 90 million cubic meters per year. A water budget for the lower aquifer has only two equal, unestimated elements, subsurface outflow and recharge from precipitation. The aquifers are generally isolated from the evaporite beds by the bounding confining beds; as a result, most ground water has little if any contact with the evaporites. No brines have been sampled and no brine discharges have been identified in the basin. Salt water has been reported for petroleum-exploration wells, but no active salt solution has been identified. (USGS)
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In order to design a network to monitor the effects of works of improvement in the Middle and North Branch Park River watersheds, and to determine the major factors controlling water-quality conditions in the watersheds, an evaluation of sediment transport, water chemistry, and biology was conducted during the spring and early summer of 1978. Major factors controlling water quality are geology, stream gradient, ground-water seepage, and the duration of streamflow. Sediment loads originate on the Pembina Escarpment. The coarse silt and sand parts of these loads are deposited on the Lake Agassiz Plain. Transport of sediment is lowered and flow duration is increased on the Middle Branch Park River due to the presence of small dams. Observations suggest that bedload transport is a significant process, particularly in the upstream reaches. However, no quantitative bedload data were collected. During periods of low flow, analyses of water from the rivers in both watersheds show downstream increases in sodium and chloride due to ground-water seepage or the unregulated flow of wells. Diversity of benthic invertebrates indicates water-quality conditions are better on the Middle Branch Park River than on the North Branch, and are better at upstream sites than at downstream sites. A program through which the Soil Conservation Service can monitor the effects of present and future works of improvement on the watersheds was designed. The monitoring program consists of intensive sampling at four locations for sediment and water chemistry during spring and early summer runoff events and by profiles of water chemistry during summer base runoff.
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