Geology Reports⌕ Search

SEARCH · Geology Reports

Results for “Southwest Hydrology”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 271 records · Page 15Linked to original sources
USGS1996

Ground-water hydrology, historical water use, and simulated ground-water flow in Cretaceous-age Coastal Plain aquifers near Charleston and Florence, South Carolina

A quasi-three-dimensional, transient, digital, ground-water flow model representing the Coastal Plain aquifers of South Carolina, has been constructed to assist in defining the ground- water-flow system of Cretaceous aquifers near Charleston and Florence, S.C. Both cities are near the centers of large (greater than 150 feet) potentiometric declines in the Middendorf aquifer. In 1989, the diameter of the depressions was approximately 40 miles at Charleston and 15 miles at Florence. The potentiometric decline occurred between predevelopment (1926) and 1982 near Florence, and between predevelopment (1879) and 1989 near Charleston. The city of Charleston does not withdraw water from these aquifers; however, some of the small communities in the area use these aquifers for a potable water supply. The model simulates flow in and between four aquifer systems. The model has a variable-cell-size grid, and spans the Coastal Plain from the Savannah River in the southwest to the Cape Fear Arch in the northeast, and from the Fall Line in the northwest to approximately 30 miles offshore to the southeast. Model-grid cell size is 1 by 1 mile in a 48 by 48 mile area centered in Charleston, and in a 36 by 48 mile area centered in Florence. The model cell size gradually increases to a maximum of 4 by 4 miles outside the two study areas. The entire grid consists of 115 by 127 cells and covers an area of 39,936 square miles. The model was calibrated to historical water-level data. The calibration relied on three techniques: (1) matching simulated and observed potentiometric map surfaces, (2) statistical comparison of observed and simulated heads, and (3) comparison of observed and simulated well hydrographs. Systematic changes in model parameters showed that simulated heads are most sensitive to changes in aquifer transmissivity. Eight predictive ground-water-use scenarios were simulated for the Mount Pleasant area, which presently (1993) uses the Middendorf aquifer as a sole-source of potable water. These simulations use various combinations of spatial distribution, and injection of treated wastewater effluent for existing and future Middendorf aquifer wells.

South Carolina↗
USGS2024

Conceptual hydrogeologic framework and groundwater budget near the southeastern part of Puget Sound, Washington

More than 1 million people live within the active model area (AMA) in the southeastern part of the lowlands surrounding Puget Sound, or Puget Lowland, Washington, and groundwater is the source for approximately one-half of their public, domestic, and irrigation water demands. The 887-square-mile AMA, located in King and Pierce Counties, represents the area of analysis for the conceptual hydrogeologic framework and numerical groundwater-flow models within the study area and includes the Puyallup River and Chambers-Clover Creek watersheds. To assess the potential hydrologic and anthropogenic impacts to groundwater and the connected surface-water resources, conceptual and numerical groundwater-flow models of groundwater flow were developed by the U.S. Geological Survey Washington Water Science Center in close cooperation with 18 water-resource agencies and stakeholders. This report presents information used to characterize the groundwater-flow system and the development of a numerical model in the AMA. Included are descriptions of the geology and conceptual hydrogeologic framework, groundwater levels and flow directions, groundwater recharge and discharge, numerical groundwater-flow model construction and results, and model limitations. The study area encompasses the western part of Pierce County and the southwestern part of King County, Washington. The study area extends south to the Nisqually River, southwest to Tanwax Creek, northeast to the Green River, and north through the valley near Auburn and adjacent uplands. It is bounded on the east by foothills of the Cascade Range, and on the northwest by Puget Sound.

Washington↗
USGS2002

Hydrogeology and leachate plume delineation at a closed municipal landfill, Norman, Oklahoma

The City of Norman operated a solid-waste municipal landfill at two sites on the Canadian River alluvium in Cleveland County, Oklahoma from 1970 to 1985. The sites, referred to as the west and east cells of the landfill, were originally excavations in the unconsolidated alluvial deposits and were not lined. Analysis of ground-water samples indicate that leachate from the west cell is discharging into an adjacent abandoned river channel, referred to as the slough, and is migrating downgradient in ground water toward the Canadian River. The report describes the hydrogeologic features at the landfill, including the topography of the bedrock, water-level changes in the alluvial aquifer, and delineates the leachate plume using specific conductance data. The leading edge of the leachate plume along the 35-80 transect extended over 250 meters downgradient of the west cell. The leading edge of the leachate plume along the 40-SOUTH transect had moved about 60 meters from the west cell in a south-southwesterly direction and had not moved past the slough as of 1997. Specific conductance measurements exceeding 7,000 microsiemens per centimeter at site 40 indicate the most concentrated part of the plume remained in the upper half of the alluvial aquifer adjacent to the west cell. The direction of ground-water flow in the alluvial aquifer surrounding the landfill was generally north-northeast to south-southwest toward the river. However, between the west cell and the slough along the 40-SOUTH transect, head measurements indicate a directional change to the east and southeast toward a channel referred to as the sewage outfall. Near the 35-80 transect, at 0.5 meter below the water table and at the base of the aquifer, the direction of ground-water flow was south-southeast with a gradient of about 30 centimeters per 100 meters. Generally, ground-water levels in the alluvial aquifer were higher during the winter months and lower during summer months, due to a normal decrease in precipitation and increased evapotranspiration in the summer. Hydrographs show temporal water-level changes in ground water and the slough, indicating a hydrologic connection between the alluvial aquifer and the slough.

Oklahoma↗
USGS2021

Factors affecting nest success of colonial nesting waterbirds in southwest Louisiana

Subsidence and accelerated sea level rise impact nesting area availability and flood probabilities of breeding islands for colonial nesting waterbirds. In 2017 and 2018, we monitored 855 nests of four species of colonial nesting waterbirds on Rabbit Island, LA, to determine factors affecting nest and chick success. Based on logistic exposure models of nests, tricolored herons had the greatest likelihood of survival to hatch (mean (95% confidence interval)) (77% (65.9–83.1%)), followed by brown pelicans (70% (59.9–98.5%)), roseate spoonbills (70% (38.9–83.8%)), and Forster’s terns (12% (10.7–12.2%)). Likelihood of survival to fledge was highest for tricolored herons (32% (12.8–40.7%)), followed by brown pelicans (28% (19.5–28.6%)), roseate spoonbills (47% (43.7–53.3%)), and Forster’s terns (0% (0.005–0.01%)). Nesting strategy and nest timing impacted survival rate; however, the effect depended on timing of inundation events as the timing of inundation events varied across years. Flooding was the primary cause of nest failure for most species. In 2003–2012, rapid expansion in brown pelican colony numbers and significant chick production occurred at Rabbit Island, but hydrologic records indicate no island inundation occurred during the breeding season from the beginning of the hydrologic record (2006) through 2011. Thus, our results contrast with those of previous studies conducted under different hydrologic conditions and demonstrate the challenges of short-term studies informing coastal restoration in a system that is influenced by multi-year to multi-decadal climatic cycles.

Louisiana↗
USGS2005

Water availability for the Western United States--Key scientific challenges

In the Western United States, the availability of water has become a serious concern for many communities and rural areas. Near population centers, surface-water supplies are fully appropriated, and many communities are dependent upon ground water drawn from storage, which is an unsustainable strategy. Water of acceptable quality is increasingly hard to find because local sources are allocated to prior uses, depleted by overpumping, or diminished by drought stress. Some of the inherent characteristics of the West add complexity to the task of securing water supplies. The Western States, including the arid Southwest, have the most rapid population growth in the United States. The climate varies widely in the West, but it is best known for its low precipitation, aridity, and drought. There is evidence that the climate is warming, which will have consequences for Western water supplies, such as increased minimum streamflow and earlier snowmelt events in snow-dominated basins. The potential for departures from average climatic conditions threatens to disrupt society and local to regional economies. The appropriative rights doctrine governs the management of water in most Western States, although some aspects of the riparian doctrine are being incorporated. The 'use it or lose it' provisions of Western water law discourage conservation and make the reallocation of water to instream environmental uses more difficult. The hydrologic sciences have defined the interconnectedness of ground water and surface water, yet these resources are still administered separately by most States. The definition of water availability has been expanded to include sustaining riparian ecosystems and individual endangered species, which are disproportionately represented in the Western States. Federal reserved rights, common in the West because of the large amount of Federal land, exist with quite senior priority dates whether or not water is currently being used. A major challenge for water users in the West is that these reserved rights may supersede other existing users. The minimum amount of water required, however, to sustain native peoples, a riparian system, or an endangered species eventually will need to be known in order to manage the available water supply. Periodic inventory and assessment of the amounts and trends of water available in surface water and ground water are needed to support water management. There is a widespread perception that the amount of available water is diminishing with time. This and other perceptions about water availability should be replaced by objective data and analysis. Some data are presented here for the major Western rivers that show that flows are not decreasing in most streams and rivers in the West. Systematic information is lacking to make broad assessments of ground-water availability, but available data for specific aquifers indicate that these aquifers are being depleted, especially near population centers. The complexity added to the issue of Western water availability by these and other factors gives rise to a significant role of science. Science has played a role in support of Western water development from the beginning, and the role has evolved and changed over time as society's values have changed. In this report, the role of science is discussed in three phases: (1) development and construction, (2) consequences and environmental awareness, and (3) sustainability. The development and construction phase includes some historical accounting of water development in the West and shows how some precedents set in those early days are still applied today.

western United States↗
USGS1980

Planning report for the southwest alluvial basins (east) regional aquifer-system analysis, parts of Colorado, New Mexico, and Texas

The study of the Southwest alluvial basins (east) will involve an analysis of the regional aquifer system in parts of Colorado, New Mexico, and Texas. This area has been divided into 22 basins. The study of the alluvial aquifer-system will be made in the following stages: (1) project planning, (2) literature searches, (3) compiling existing data, (4) data collection, (5) basin modeling, (6) regional aquifer modeling, and (7) reports. The regional aquifer study will be accomplished through studying each of the 22 basins. Data compilation and limited data collection will be part of each basin study. Digital computer models will be made for those basins where data are sufficient. A regional aquifer model will be developed from the basin models. In addition to this report, there will be basin hydrology reports and the final regional report. Included in the final report will be a description of the regional hydrology and geology. (USGS)

Open-File Report↗
USGS1985

Ground-water flow in the Prairie du Chien-Jordan aquifer related to contamination by coal-tar derivatives, St. Louis Park, Minnesota

A three-dimensional, ground-water-flow model of the Prairie du Chien-Jordan aquifer and associated hydrogeologic units was developed to evaluate the movement of coal-tar derivatives from a coal-tar distillation and wood-preserving plant in St. Louis Park, Minnesota. A finite-difference grid was superimposed on the modeled area, which includes most of eastern Hennepin County. The individual cells are 400-foot squares in the center of the grid (St. Louis Park area); the cells increase in dimension toward the outside limits of the grid. Five geologic units are represented by four layers in the model. These units include the Jordan Sandstone, the Prairie du Chien Group (dolomite and sandy dolomite), the basal confining unit of the St. Peter Sandstone (silty and sandy shale), the St. Peter Sandstone, and glacial deposits in bedrock valleys. The model was calibrated for steady-state conditions for a period before significant ground-water development (1885-1930) and for a period of significant pumping stress (winter conditions, 1970 fs). A transient calibration was accomplished by simulation of a period during which seasonal changes in potentiometric head in the Prairie du Chien-Jordan aquifer were significant (1977-80). Sensitivity testing indicated that leakage to the upper model layer and the vertical hydraulic conductivity of the basal confining unit of the St. Peter Sandstone were the model hydrologic properties which, when changed, resulted in the greatest changes in model-calculated water levels. The calibrated model generally calculates water levels that are within 10 feet of measured values. Model simulations indicate that the potentiometric surface of the Prairie du Chien-Jordan aquifer would be raised by as much as 3 feet in the area of the plant site by water introduced into the aquifer through wells open to more than one aquifer system. The cones of impression created at these wells could have a significant impact on the transport of contaminants in the Prairie du Chien-Jordan. The presence of coal-tar derivatives in the aquifer has been difficult to explain in wells located upgradient from the plant site to the north, west, and southwest. Simulations suggest that, during periods of heavy withdrawal from certain of these wells (SLP10, SLP15, and SLP5), local hydraulic gradients may have been altered, resulting in the potential for the movement of contaminants from the area of the plant site to the wells. Cones of impression at multiaquifer wells near the plant site contributed to the alteration of local gradients. Simulation of a proposed gradient-control plan, in which lateral homogeneity and isotropy of individual hydro geologic units was assumed, indicates that the actions would be effective in limiting expansion of the contaminated volume in the Prairie du Chien-Jordan aquifer. The plan includes the control of withdrawal from five wells. The simulations also show, however, that modelcalculated potentiometric surfaces are sensitive to changes in withdrawal rates at wells not intended to be under the control of the plan. Management of discharge from these wells also will be important to overall effectiveness of the remedial-action plan.

Minnesota↗
USGS1995

Hydrogeology and water quality at the management systems evaluation area near Piketon, Ohio

This report presents the results of a study by the U.S. Geological Survey, The Ohio State University, and the U.S. Department of Agriculture to describe the hydrology, water quality, and geochemical factors controlling water quality at the Ohio Management Systems Evaluation Area (MSEA). The Ohio MSEA is located on a 650-acre farm in the Scioto River Valley in Pike County, south-central Ohio. The farm is underlain by an incised bedrock valley filled with about 70 feet of sand and gravel outwash deposits that are covered by a veneer of silty clay alluvium and silty loam and sandy loam soils. Outwash sediment are composed predominantly of dolomite, quartz, and calcite, and have a median organic carbon concentration of 0.39 weight percent. Horizontal hydraulic conductivity of the sediment based on results of multiple-well aquifer tests ranges from 400 to 560 feet per day. Ground-water flow is from east to west-southwest at an average velocity of 1.5 to 2.5 feet per day. Ground water and surface water at the site are highly interconnected. Big Beaver Creek recharges the outwash aquifer along the eastern edge of the study area, and ground water discharges to the Scioto River at the western edge of the study area. High-stage events on the Scioto River cause frequent flow reversals in the aquifer that allow streamwater to travel a maximum observed distance of 190 feet inland. A zone of oxidizing waters (characterized by high dissolved oxygen concentration and Eh) is found in shallow ground water for several hundred feet adjacent to Big Beaver Creek and the Scioto River. This zone of oxidizing ground water is caused by the periodic inflow of surface waters to the aquifer. A ground-water budget for the study area indicates that the aquifer received 17.7 inches of recharge during water year 1992; of this amount, 72 percent originated as infiltrating precipitation, 28 percent as infiltration of surface water from Big Beaver Creek, and 0.2 percent as leakage from bedrock. Areal variation in water quality is caused by areal differences in the relative importance of these three recharge sources. The effects of bedrock leakage are evident only in the northeast corner of the study area. Here, deep outwash waters are transitional in composition between the calcium magnesium bicarbonate waters found elsewhere in the outwash aquifer and the calcium sodium chloride waters of the bedrock aquifer. Mixing calculations indicate that these deep outwash waters are composed of as much as 26 percent bedrock water. In the southern part of the MSEA, ground water is diluted by surface water from Big Beaver Creek as it recharges the aquifer through a sand and gravel streambed. At the northeast corner of the MSEA, however, Big Beaver Creek flows across a shale streambed through which no infiltration occurs. Redox reactions in the outwash aquifer control variations in aquifer chemistry with depth. From the water table to about 40 feet below land surface, oxidizing conditions are characterized by the presence of dissolved oxygen and nitrates in ground water, Eh greater than 200 millivolts, ferrihydrite coatings on sediment grains, and the absence of dissolved iron and manganese. From about 40 feet below land surface to the base of the aquifer, reducing conditions are characterized by dissolved oxygen concentrations less than 2 mg/L, Eh less than 200 millivolts, and the presence of dissolved iron and manganese. Denitrification in the reducing zone naturally remediates anthropogenic nitrate contamination of the aquifer while oxidizing pyrite in the aquifer sediment.

Ohio↗
USGS2020

Historical and prehistorical water levels of Mormon Lake, Arizona as a measure of climate change on the southwest Colorado Plateau, USA

Mormon Lake, elevation 2166 m with maximum historic surface area of 31.4 km 2 , lies in a forested endorheic basin covering 103 km 2 . It is the largest unaltered freshwater body on the 337,000 km 2 Colorado Plateau. Prehistorical (before AD 1878) highstands were ca. 9 and 24 m relative to depocenter datum. These levels likely occurred during four multidecadal episodes of cool, wet conditions between ca. 3.55 and 0.20 ka BP. Maximum historical levels (early 1900s) were up to 7.9 m, whereas modern (post-1941) levels were frequently zero or relatively low. Historical climate records indicate reconstructed lake levels correlate directly with annual precipitation and inversely with temperature. Early highstands were associated with above average precipitation and the lowest temperatures of the 116 yr record. The lake receded after 1941; thereafter, frequent drying and low-water levels resulted from recurrent drought and steadily increasing temperatures. Consequently, a wet episode from the 1970s to the 1990s had precipitation like the early 1900s, but highstands were only ca. 3.8 m. The historical lake-level chronology is consistent with changes of hydrologic balance predicted by climate models, that is, reduced effective precipitation (precipitation minus evaporation). These changes, particularly aridification, apparently began in the 1970s or earlier. Global oceanic and atmospheric climate modulate lake levels and regional hydroclimate.

Arizona↗
USGS2022

Hydrologic effects of leakage from the Catskill Aqueduct on the bedrock-aquifer system near High Falls, New York, November 2019–January 2020

Historical observations by the New York City Department of Environmental Protection (NYCDEP) indicate that the Rondout pressure tunnel has been leaking in the vicinity of the hamlet of High Falls, New York. In the 74 days from November 11, 2019, to January 23, 2020, NYCDEP shut down and partially dewatered the pressure tunnel for inspection and repairs. On November 5–7, 2019 (during normal tunnel operations), and on January 21–22, 2020 (when the tunnel was shut down), the U.S. Geological Survey used a network of 31 groundwater wells to collect water-level elevations and determine the potentiometric surface of the bedrock aquifer adjacent to the Rondout pressure tunnel. When the tunnel was fully pressurized during normal operations, water levels indicated a two-mile-long groundwater mound which trended northeastward, approximately along the regional strike of the bedrock units. The mound ranged in elevation from 250 to 300 feet (ft) above the North American Vertical Datum of 1988 and extended from 1,500 ft southwest of a suspected leak at the Rondout pressure tunnel to about 8,500 ft northeast of the possible leak. During the 74-day shutdown, during which the aqueduct was nonoperational, this groundwater mound decreased in magnitude and extent as it reverted to equilibrium conditions. This resulted in a flattening of the potentiometric surface, represented by two remnant groundwater plateaus. Water-level differences were calculated for wells that may be affected by potential tunnel leakage to determine the influence on the local bedrock aquifer. The five largest water-level differences (77, 61, 49, 42, and 41 ft) occurred in wells that were generally aligned with the northeastward trend of regional bedrock strike; these wells may penetrate the karstic Helderberg Group bedrock unit. Near the suspected tunnel leak, the Helderberg Group overlies the Binnewater Sandstone and the High Falls Shale, both of which produced substantial groundwater inflows during the construction of the Rondout pressure tunnel. Water levels in wells penetrating the Shawangunk Formation just east of Rondout Creek, where the unit is in contact with the High Falls Shale, and in wells penetrating the Esopus Shale, which is adjacent to the Helderberg Group and northwest of the tunnel leak, may be affected by tunnel leakage. It is unclear if water levels in a well 9,000 ft northwest of the suspected tunnel leak are influenced by the tunnel leakage, by another source of artificial recharge, or by both. This well penetrates the Onondaga Limestone in the northwestern part of the study area. An unconsolidated aquifer composed of stratified gravel, sand, silt, and clay overlies the limestone bedrock in this part of study area―additional study is required to determine if this unconsolidated aquifer is affected by tunnel leakage.

New York↗
USGS1996

Use of precipitation and groundwater isotopes to interpret regional hydrology on a tropical volcanic island: Kilauea volcano area, Hawaii

Isotope tracer methods were used to determine flow paths, recharge areas, and relative age for groundwater in the Kilauea volcano area of the Island of Hawaii. A network of up to 66 precipitation collectors was emplaced in the study area and sampled twice yearly for a 3-year period. Stable isotopes in rainfall show three distinct isotopic gradients with elevation, which are correlated with trade wind, rain shadow, and highelevation climatological patterns. Temporal variations in precipitation isotopes are controlled more by the frequency of storms than by seasonal temperature fluctuations. Results from this study suggest that (1) sampling network design must take into account areal variations in rainfall patterns on islands and in continental coastal areas and (2) isotope/elevation gradients on other tropical islands may be predictable on the basis of similar climatology. Groundwater was sampled yearly in coastal springs, wells, and a few high-elevation springs. Areal contrasts in groundwater stable isotopes and tritium indicate that the volcanic rift zones compartmentalize the regional groundwater system, isolating the groundwater south of Kilauea's summit and rift zones. Part of the Southwest Rift Zone appears to act as a conduit for water from higher elevation, but there is no evidence for downrift flow in the springs and shallow wells sampled in the lower East Rift Zone.

Water Resources Research↗
USGS1986

Compilation and preliminary interpretation of hydrologic data for the Weldon Spring radioactive waste-disposal sites, St Charles County, Missouri — A progress report

The Weldon Spring Chemical Plant is located just north of the drainage divide separating the Mississippi River and the Missouri River in St. Charles County, Missouri. From 1957 to 1966 the plant converted uranium-ore concentrates and recycled scrap to pure uranium trioxide, uranium tetrafluoride, and uranium metal. Residues from these operations were pumped to four large pits that had been excavated near the plant. Small springs and losing streams are present in the area. Water overlying the residue in the pits has a large concentration of dissolved solids and a different chemical composition compared to the native groundwater and surface water. This difference is indicated by the concentrations of calcium, sodium, sulfate, nitrate, fluoride, uranium, radium, lithium, molybdenum, strontium, and vanadium, all of which are greater than natural or background concentrations. Water from Burgermeister Spring, located about 1.5 miles north of the chemical plant area, contains uranium and nitrate concentrations greater than background concentrations. Groundwater in the shallow bedrock aquifer moves northward from the vicinity of the chemical plant toward Dardenne Creek. An abandoned limestone quarry several miles southwest of the chemical plant also has been used for the disposal of radioactive waste and rubble. Groundwater flow from the quarry area is southward through the alluvium, away from the quarry and toward the Missouri River. The St. Charles County well field is located in the Missouri River flood plain near the quarry and the large yield wells are open to the Missouri River alluvial aquifer. Water from a well 4,000 ft southeast of the quarry was analyzed; there was no indication of contamination from the quarry. Additional water quality and water level data are needed to determine if water from the quarry moves toward the well field. Observation wells need to be installed in the area between the chemical plant, pits, and Dardenne Creek. The wells would be used to provide access for measurements of depth to ground water and for the collection of water samples from the shallow bedrock aquifer.

Missouri↗
USGS2019

Groundwater availability in the Ozark Plateaus aquifer system

Executive Summary The study described in this report, initiated by the U.S. Geological Survey in 2014, was designed to evaluate fresh groundwater resources within the Ozark Plateaus, central United States, as an area within a broader national assessment of groundwater availability. The goals of the Ozark study were to evaluate historical effects of human activities on water levels and groundwater availability, quantify groundwater resources now and under probable future pumping and climate conditions, and evaluate existing monitoring networks for their value in making better predictions of future groundwater resources. Previous studies include simulation of local-scale groundwater flow under varying temporal scales, or simulation of the regional system under steady-state conditions. While these studies are useful, particularly for the problem for which they were designed, there is a need to look at the larger regional system under transient conditions to fully evaluate the water resource over time. This study focused on multiple spatial and temporal scales to examine changes in groundwater pumping, storage, and water-level declines. The regional scale provides a broad view of the sources and demands on the system with time. The study area covers approximately 68,000 square miles in the central United States in parts of Missouri, Arkansas, Kansas, and Oklahoma and encompasses the Ozark Plateaus Physiographic Province (Ozark Plateaus), including the Salem Plateau, Springfield Plateau, and Boston Mountains. Groundwater is withdrawn from the Ozark Plateaus aquifer system (Ozark system) for public supply and for domestic, agriculture (including irrigation and aquaculture), livestock, and non-agricultural use (including industrial, thermoelectric power generation, mining, and commercial). The Ozark system provides an important drinking-water supply for people living in the Ozark Plateaus because public supply and domestic use combined constitute the largest groundwater use. Precipitation is the ultimate source of freshwater to the Ozark system; most rainfall occurs during April, May, and June, and precipitation increases generally from north to south across the study area. Groundwater use currently accounts for only 10 percent of the total water use in the areas overlying the Ozark system, but provides a critical drinking-water resource because public supply and domestic groundwater withdrawals are largely from groundwater resources. The 380 million gallons per day of groundwater withdrawn from the Ozark system in 2010 accounts for approximately 2 percent of recharge. Although groundwater use represents a small component of the hydrologic budget, because of low storage in aquifer units, cones of depression with steep water-level gradients can develop quickly around pumping centers. The amount of water entering and leaving the aquifer system from 1900 to about 1965 was relatively constant at a rate of about 13 billion gallons per day (Bgal/d). Much of this inflow of water is discharged through streams in the system to balance the hydrologic budget. Changes in storage over time (from outflows to inflows) reflect the large variability in recharge: if recharge decreases, water levels will decrease, resulting in less groundwater discharge to streams and more water released from aquifer storage. Conversely, when recharge increases, water levels increase, more groundwater discharges to streams, and aquifer storage is replenished. Although pumping generally increased from 1900 to 2016, it does not appear to correlate with the change in storage over the same time period. Regionally, simulated change in groundwater storage corresponds with changes in recharge, more so than with increases in pumping. Average recharge was 11.6 Bgal/d for the period 1900 to 2016. Recharge was generally above average from predevelopment to 1965, followed by a period of below-average recharge from 1965 to about 1980. Recharge remained consistently above average from 1980 to about 1988, after which there was a period of average or below-average recharge, reflected by a decline through the mid-2000s. The implications and potential effects of increased pumping and long-term climate change on the Ozark Plateaus hydrologic system and groundwater availability are a concern for communities and resource managers in the area. Pumping varies from year to year, but is generally expected to moderately increase with population, industrial, and agricultural needs. Most climate models predict warmer minimum and maximum air temperatures by midcentury in the Ozark Plateaus area, especially from midspring through early fall. Three scenarios were developed to simulate possible future conditions from 2016 to 2060 and assess the potential effects on the hydrologic system and availability of water resources. For each scenario, changes in water levels and hydrologic budget components were evaluated from predevelopment (1900) to present (2016) and 45 years into the future (2060). The baseline scenario represents an extension of the average (1996 to 2016) seasonal pumping and recharge values. The pumping scenario is an extension of the average (1996 to 2016) seasonal recharge values with increases in pumping following the historical trend for the period 2016–2060 of up to 120 percent of the 1996 to 2016 average seasonal pumping values. The general circulation model (GCM) scenario is an extension of the average (1996 to 2016) seasonal pumping values and variable recharge based on seasonal averages of soil water storage from a water-balance model using temperature and precipitation from multiple GCMs. The general patterns of water-level decline are similar for each scenario. The areas of water-level decline in southwest Missouri and northeast Oklahoma are only marginally different by 2060 from those of 2009. In one area south of Springfield, Mo., water-level declines are less in the baseline and GCM scenarios than in 2009. This may be the result of a transition from groundwater use to surface-water supplies for a larger percentage of the demand in the area. For all three scenarios, forecasted pumping, recharge, and aquifer properties play an important role in determining the uncertainty of water-level forecasts at 94 real-time observation wells. Simulated aquifer properties in the productive middle and lower Ozark aquifers and the St. Francois confining unit of the Ozark system contribute most to predictive uncertainty in water levels at approximately 35 percent of the real-time observation wells. Out of the 94 real-time observation wells, 82 are developed in the lower Ozark aquifer.

Arkansas, Kansas, Missouri, Oklahoma↗
USGS2006

Geologic map of the Peach Springs 30' x 60' quadrangle, Mohave and Coconino counties, northwestern Arizona

This map is a product of a cooperative project of the U.S. Geological Survey, the U.S. National Park Service, and the Bureau of Land Management to provide geologic map coverage and regional geologic information for visitor services and resource management of Grand Canyon National Park, Lake Mead National Recreation Area, Grand Canyon-Parashant-National Monument, and adjacent lands in northwestern Arizona. This map is a synthesis of previous and new geologic mapping that encompasses the Peach Springs 30' x 60' quadrangle, Arizona. The geologic data will support future geologic, biologic, hydrologic, and other science resource studies of this area conducted by the National Park Service, the Hualapai Indian Tribe, the Bureau of Land Management, the State of Arizona, and private organizations. The Colorado River and its tributaries have dissected the southwestern Colorado Plateau into what is now the southwestern part of Grand Canyon. The erosion of Grand Canyon has exposed about 426 m (1,400 ft) of Proterozoic crystalline metamorphic rocks and granite, about 1,450 m (4,760 ft) of Paleozoic strata, and about 300 m (1,000 ft) of Tertiary sedimentary rocks. Outcrops of Proterozoic crystalline rocks are exposed at the bottom of Grand Canyon at Granite Park from Colorado River Mile 207 to 209, at Mile 212, and in the Lower Granite Gorge from Colorado River Mile 216 to 262, and along the Grand Wash Cliffs in the southwest corner of the map area.

Arizona↗
USGS1956

Ground water in northeastern Louisville, Kentucky with reference to induced infiltration

In cooperation with the city of Louisville, Ky., the U. S. Geological Survey made a detailed investigation during the period February 1945 to March 1947 of the ground-water resources of a 3-square-mile area along the Ohio River north-east of Louisville. Test drilling shows that the principal aquifer consists of about 80 feet of glacial-outwash sands and gravels lying in an old river channel which was cut into rocks of Ordovician, Silurian, and Devonian age. The total ground-water storage in the area is estimated as 7 billion gallons. The ground-water levels are affected by changes in river elevation, by rainfall, and by the effects of pumping in the downtown part of Louisville 3 miles to the southwest. In the northeastern part of the area the flow of ground water, as defined by contour maps, is toward the river, and in the southwestern part of the area it is from the river toward the downtown area of overpumping. Ground water in the area has an average temperature of 56° F. The water, which is moderately hard, is suitable for domestic and industrial uses. Analysis of a pumping test made during the investigation proves that infiltration supplies can be developed. Studies to determine the degree of connection between the river and aquifer were made on the basis of chemical analyses, sections showing temperature distribution in the aquifer during the pumping test, shapes of water-level profiles in the test area, and shapes of time-drawdown curves for a number of observation wells. Quantitative studies to evaluate the hydrologic constants of the aquifer were made by both graphical and mathematical methods. The transmissibility was determined as 121,000 gpd/ft in the test area; the distance to the line source, 400 feet; and the coefficient of storage, 0.0003. A comparison of river-level fluctuations and water-level fluctuations in observation wells shows that conditions along the 6.4-mile reach of river are not greatly different from those at the site of the pumping test. It is estimated that under adverse temperature and river-stage conditions infiltration supplies could be developed to the extent of 280 million gpd in the entire 6.4-mile reach investigated; at average river-water temperature (59° F) about 400 million gpd could be developed. Diagrams were drawn showing the estimated yield of wells of different radii, at various distances from the river, and at various spacings. In making the computations allowance was made for screen losses, dewatering of the aquifer, partial penetration of wells, location wells, eccentricity of large wells, and interference among wells.

Kentucky↗
USGS2009

Assessment of Local Recharge Area Characteristics of Four Caves in Northern Arkansas and Northeastern Oklahoma, 2004-07

A study was conducted from 2004 to 2007 by the U.S. Geological Survey in cooperation with the U.S. Fish and Wildlife Service to assess the characteristics of the local recharge areas of four caves in northern Arkansas and northeastern Oklahoma that provide habitat for a number of unique organisms. Characterization of the local recharge areas are important because the caves occur in a predominately karst system and because land use proximal to the caves, including areas suspected to lie within the local recharge areas, may include activities with potentially deleterious effects to cave water quality. An integrated approach was used to determine the hydrogeologic characteristics and the extent of the local recharge areas of Civil War Cave, January-Stansbury Cave, Nesbitt Spring Cave, and Wasson's Mud Cave. This approach incorporated methods of hydrology, structural geology, geomorphology, and geochemistry. Continuous water-level and water-temperature data were collected at each cave for various periods to determine recharge characteristics. Field investigations were conducted to determine surficial controls affecting the groundwater flow and connections of the groundwater system to land-surface processes in each study area. Qualitative groundwater tracing also was conducted at each cave to help define the local recharge areas. These independent methods of investigation provided multiple lines of evidence for effectively describing the behavior of these complex hydrologic systems. Civil War Cave is located near the city of Bentonville in Benton County, Arkansas, and provides habitat for the Ozark cavefish. Civil War Cave is developed entirely within the epikarst of the upper Boone Formation, and recharge to Civil War Cave occurs from the Boone Formation (Springfield Plateau aquifer). The daily mean discharge for the period of study was 0.59 cubic feet per second and ranged from 0.19 to 2.8 cubic feet per second. The mean water temperature for Civil War Cave was 14.0 degrees Celsius. The calculated recharge area for Civil War Cave ranged from 0.13 to 2.5 square miles using the water-balance equation to 3.80 square miles using a normalized base-flow method. Tracer tests indicated a portion of the water within Civil War Cave was from across a major topographic divide located to the southwest. January-Stansbury Cave is located in Delaware County in northeastern Oklahoma, and provides habitat for the Oklahoma cave crayfish and the Ozark cavefish. January-Stansbury Cave is developed in the St. Joe Limestone member of the Boone Formation. The daily mean discharge for the period of study was 1.0 cubic foot per second and ranged from 0.35 to 8.7 cubic feet per second. The mean water temperature for January-Stansbury Cave was 14.3 degrees. The calculated recharge area for January-Stansbury Cave using the water-balance equation ranged from approximately 0.04 to 0.83 square miles. Tracer tests generally showed water discharging from January-Stansbury Cave during high flow originates from within the topographic drainage area and from an area outside the topographic drainage area to the southwest. Nesbitt Spring Cave is located near the city of Mountain View in north-central Arkansas and provides habitat for the Hell Creek cave crayfish. Nesbitt Spring Cave is developed in the Plattin Limestone (Ozark aquifer) and is recharged through the Boone Formation (Springfield Plateau aquifer). The mean daily discharge for the period of study was 4.5 cubic feet per second and ranged from 0.39 to 70.7 cubic feet per second. The mean water temperature for Nesbitt Spring Cave was 14.2 degrees Celsius. The calculated recharge area for Nesbitt Spring Cave using the water-balance equation ranged from 0.49 square mile to 4.0 square miles. Tracer tests generally showed a portion of water discharging from Nesbitt Spring during high flow originates from outside the topographic drainage area. Wasson's Mud Cave is located near the city of Springtown

Scientific Investigations Report↗
USGS2003

Geology of the MER 2003 "Elysium" candidate landing site in southeastern Utopia Planitia, Mars

The NASA Mars Exploration Rover (MER) Project has been considering a landing-site ellipse designated EP78B2 in southeastern Utopia Planitia, southwest of Elysium Mons. The site appears to be relatively safe for a MER landing site because of its predicted low wind velocities in mesoscale atmospheric circulation models and its low surface roughness at various scales as indicated by topographic and imaging data sets. Previously, the site's surface rocks have been interpreted to be marine sediments or lava flows. In addition, we suggest that Late Noachian to Early Hesperian collapse and mass wasting of Noachian highland rocks contributed to the deposition of detritus in the area of the ellipse. Furthermore, we document partial Late Hesperian to Early Amazonian resurfacing of the ellipse by flows and vents that may be of mud or silicate volcanic origin. A rover investigation of the Utopia landing site using the MER Athena instrument package might address some fundamental aspects of Martian geologic evolution, such as climate change, hydrologic evolution, and magmatic and tectonic history.

Journal of Geophysical Research E: Planets↗
USGS1994

The volcanic, sedimentologic, and paleolimnologic history of the Crater Lake caldera floor, Oregon:Evidence for small caldera evolution

Apparent phreatic explosion craters, caldera-floor volcanic cones, and geothermal features outline a ring fracture zone along which Mount Mazama collapsed to form the Crater Lake caldera during its climactic eruption about 6,850 yr B.P. Within a few years, subaerial deposits infilled the phreatic craters and then formed a thick wedge (10-20 m) of mass flow deposits shed from caldera walls. Intense volcanic activity (phreatic explosions, subaerial flows, and hydrothermal venting) occurred during this early postcaldera stage, and a central platform of subaerial andesite flows and scoria formed on the caldera floor. Radiocarbon ages suggest that deposition of Iacustrine hemipelagic sediment began on the central platform about 150 yr after the caldera collapse. This is the minimum time to fill the lake halfway with water and cover the platform assuming present hydrologic conditions of precipitation and evaporation but with negligible leakage of lake water. Wizard Island formed during the final part of the 300-yr lake-filling period as shown by its (1) upper subaerial lava flows from 0 to -70 m below present water level and lower subaqueous lava flows from -70 to -500 m and by (2) lacustrine turbidite sand derived from Wizard Island that was deposited on the central platform about 350 yr after the caldera collapse. Pollen stratigraphy indicates that the warm and dry climate of middle Holocene time correlates with the early lake deposits. Diatom stratigraphy also suggests a more thermally stratified and phosphate-rich environment associated respectively with this climate and greater hydrothermal activity during the early lake history. Apparent coarse-grained and thick-bedded turbidites of the early lake beds were deposited throughout northwest, southwest, and eastern basins during the time that volcanic and seismic activity formed the subaqueous Wizard Island, Merriam Cone, and rhyodacite dome. The last known postcaldera volcanic activity produced a subaqueous rhyodacite ash bed and dome about 4,240 yr B.P. The late lake beds with base-of-slope aprons and thin, fine-grained basin-plain turbidites were deposited during the volcanically quiescent period of the past 4,000 yr. Deposits in Crater Lake and on similar caldera floors suggest that four stages characterize the postcaldera evolution of smaller (≤10 km in diameter) terrestrial caldera lake floors: (1) initial-stage caldera collapse forms the ring fracture zone that controls location of the main volcanic eruptive centers and sedimentary basin depocenters on the caldera floor; (2) early-stage subaerial sedimentation rapidly fills ring-fracture depressions and constructs basin-floor debris fans from calderawall landslides; (3) first-stage subaqueous sedimentation deposits thick flat-lying lake turbidites throughout basins, while a thin blanket of hemipelagic sediment covers volcanic edifices that continue to form concurrently with lake sedimentation; and (4) second-stage subaqueous sedimentation after the waning of major volcanic activity and the earlier periods of most rapid sedimentation develops small sili-ciclastic basin base-of-slope turbidite aprons and central basin plains. Renewed volcanic activity or lake destruction could cause part or all of the cycle to repeat.

Oregon↗