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

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At least 1,441 records · Page 80Linked to original sources
USGS2012

Groundwater data for selected wells within the Eastern San Joaquin Groundwater Subbasin, California, 2003-8

Data were collected by the U.S. Geological Survey from 2003 through 2008 in the Eastern San Joaquin Groundwater Subbasin, 80 miles east of San Francisco, California, as part of a study of the increasing chloride concentrations in groundwater processes. Data collected include geologic, geophysical, chemical, and hydrologic data collected during and after the installation of five multiple-well monitoring sites, from three existing multiple-well sites, and from 79 selected public-supply, irrigation, and domestic wells. Each multiple-well monitoring site installed as part of this study contained three to five 2-inch diameter polyvinyl chloride (PVC)-cased wells ranging in depth from 68 to 880 feet below land surface. Continuous water-level data were collected from the 19 wells installed at these 5 sites and from 10 existing monitoring wells at 3 additional multiple-well sites in the study area. Thirty-one electromagnetic logs were collected seasonally from the deepest PVC-cased monitoring well at seven multiple-well sites. About 200 water samples were collected from 79 wells in the study area. Coupled well-bore flow data and depth-dependent water-quality data were collected from 12 production wells under pumped conditions, and well-bore flow data were collected from 10 additional wells under unpumped conditions.

California↗
USGS2006

Magnetotelluric data collected near geophysically logged boreholes in the Española and Middle Rio Grande Basins, New Mexico

The Santa Fe region is growing rapidly. The Santa Fe Group aquifer in the Española Basin is the main source of municipal water for the region, and water shortfalls could have serious consequences. Future growth and land management in the region depend on accurate assessment and protection of the region's ground-water resources. An important issue in managing the ground-water resources is a better understanding of the hydrogeology of the Tertiary Santa Fe Group. The Santa Fe Group includes the sedimentary deposits that fill the Rio Grande rift and contain the principal ground-water aquifers. The U.S. Geological Survey (USGS) is conducting a series of multidisciplinary studies of the Española Basin in northern New Mexico. Detailed geologic mapping, high-resolution airborne magnetic surveys, electromagnetic surveys, and hydrologic, lithologic, and hydro-geochemical data are being used to better understand the aquifer systems. Magnetotelluric (MT) surveys were completed as part of these studies. The primary purpose of the MT surveys was to map changes in electrical resistivity with depth that are related to differences in various rock types that help control the properties of aquifers in the region. Resistivity modeling of the MT data can be used to investigate buried structures related to the basic geologic framework of the study area. The purpose of this report is to release MT sounding data collected near geophysically logged boreholes in the study area, including the nearby Middle Rio Grande Basin. This MT data can be used in subsequent resistivity modeling. No interpretation of the data is included in this report.

New Mexico↗
USGS1967

Areal geology of the western Mojave Desert, California

This report and map represent part of a geologic investigation by the U.S. Geological Survey of the known and potential deposits of borate minerals in the southern California desert regions. The primary purpose of this report and the geologic map (pl. 1) is to provide a geologic background for the exploration for possible concealed borate deposits in the western Mojave Desert, based upon (1) the geology of the known deposits of these minerals within the region, (2) the areal geology of the region, and (3) the subsurface geology as determined insofar as possible from logs of exploratory test holes, mine workings, and geophysical data. Available logs of test holes so used, including those drilled for petroleum and some for water, and of borate mine shafts are summarized in tabulated form (tables 2-4); the gravity geophysical data are published separately (Mabey, 1960). The resulting geologic data are of use for many secondary purposes, such as exploration for other commodities, including petroleum and gas, and in evaluation of ground-water conditions. The base for the geologic map was prepared by joining parts of the Bakersfield, Trona, Los Angeles, and San Bernardino quadrangles, as published by the U.S. Geological Survey at a scale of 1:250,000, and then enlarging the mosaicked map to a scale of 1:125,000. Although lacking in detail and accuracy, the base is the best that is available. Numerous maps at a scale of an inch to a mile or larger show the geology of most of the complex areas in greater detail.

California↗
USGS2007

Time-domain electromagnetic soundings to characterize water quality within a freshwater/saline-water transition zone, Estancia Valley, New Mexico, July 2005: A reconnaissance study

During July 2005, the U.S. Geological Survey, in cooperation with the New Mexico Bureau of Geology and Mineral Resources, conducted a reconnaissance study in the Estancia Valley in central New Mexico to characterize water quality using time-domain electromagnetic (TDEM) surface-geophysical soundings. TDEM sounding is one of a number of surface geophysical methods that provide a relatively quick and inexpensive means to characterize subsurface geologic and hydrogeologic properties. TDEM surface geophysical methods can be used to detect variations in the electrical resistivity of the subsurface, which in turn can be related to variations in the physical and chemical properties of soil, rock, and pore fluids.

New Mexico↗
USGS2000

Hydrogeology and simulation of ground-water flow at the Gettysburg Elevator Plant Superfund Site, Adams County, Pennsylvania

Ground water in Triassic-age sedimentary fractured-rock aquifers in the area of Gettysburg, Pa., is used as drinking water and for industrial and commercial supply. In 1983, ground water at the Gettysburg Elevator Plant was found by the Pennsylvania Department of Environmental Resources to be contaminated with trichloroethene, 1,1,1-trichloroethane, and other synthetic organic compounds. As part of the U.S. Environmental Protection Agency?s Comprehensive Environmental Response, Compensation, and Liability Act, 1980 process, a Remedial Investigation was completed in July 1991, a method of site remediation was issued in the Record of Decision dated June 1992, and a Final Design Report was completed in May 1997. In cooperation with the U.S. Environmental Protection Agency in the hydrogeologic assessment of the site remediation, the U.S. Geological Survey began a study in 1997 to determine the effects of the onsite and offsite extraction wells on ground-water flow and contaminant migration from the Gettysburg Elevator Plant. This determination is based on hydrologic and geophysical data collected from 1991 to 1998 and on results of numerical model simulations of the local ground-water flow-system. The Gettysburg Elevator Site is underlain by red, green, gray, and black shales of the Heidlersburg Member of the Gettysburg Formation. Correlation of natural-gamma logs indicates the sedimentary rock strike about N. 23 degrees E. and dip about 23 degrees NW. Depth to bedrock onsite commonly is about 6 feet but offsite may be as deep as 40 feet. The ground-water system consists of two zones?a thin, shallow zone composed of soil, clay, and highly weathered bedrock and a thicker, nonweathered or fractured bedrock zone. The shallow zone overlies the bedrock zone and truncates the dipping beds parallel to land surface. Diabase dikes are barriers to ground-water flow in the bedrock zone. The ground-water system is generally confined or semi-confined, even at shallow depths. Depth to water can range from flowing at land surface to more than 71 feet below land surface. Potentiometric maps based on measured water levels at the Gettysburg Elevator Plant indicate ground water flows from west to east, towards Rock Creek. Multiple-well aquifer tests indicate the system is heterogeneous and flow is primarily in dipping beds that contain discrete secondary openings separated by less permeable beds. Water levels in wells open to the pumped bed, as projected along the dipping stratigraphy, are drawn down more than water levels in wells not open to the pumped bed. Ground-water flow was simulated for steady-state conditions prior to pumping and long-term average pumping conditions. The three-dimensional numerical flow model (MODFLOW) was calibrated by use of a parameter estimation program (MODFLOWP). Steady-state conditions were assumed for the calibration period of 1996. An effective areal recharge rate of 7 inches was used in model calibration. The calibrated flow model was used to evaluate the effectiveness of the current onsite and offsite extraction well system. The simulation results generally indicate that the extraction system effectively captures much of the ground-water recharge at the Gettysburg Elevator Plant and, hence, contaminated ground-water migrating from the site. Some of the extraction wells pump at low rates and have very small contributing areas. Results indicate some areal recharge onsite will move to offsite extraction wells.

Pennsylvania↗
USGS2010

Quantifying canal leakage rates using a mass-balance approach and heat-based hydraulic conductivity estimates in selected irrigation canals, western Nebraska, 2007 through 2009

The water supply in areas of the North Platte River Basin in the Nebraska Panhandle has been designated as fully appropriated or overappropriated by the Nebraska Department of Natural Resources (NDNR). Enacted legislation (Legislative Bill 962) requires the North Platte Natural Resources District (NPNRD) and the NDNR to develop an Integrated Management Plan (IMP) to balance groundwater and surface-water supply and demand in the NPNRD. A clear understanding of the groundwater and surface-water systems is critical for the development of a successful IMP. The primary source of groundwater recharge in parts of the NPNRD is from irrigation canal leakage. Because canal leakage constitutes a large part of the hydrologic budget, spatially distributing canal leakage to the groundwater system is important to any management strategy. Surface geophysical data collected along selected reaches of irrigation canals has allowed for the spatial distribution of leakage on a relative basis; however, the actual magnitude of leakage remains poorly defined. To address this need, the U.S. Geological Survey, in cooperation with the NPNRD, established streamflow-gaging stations at upstream and downstream ends from two selected canal reaches to allow a mass-balance approach to be used to calculate daily leakage rates. Water-level and sediment temperature data were collected and simulated at three temperature monitoring sites to allow the use of heat as a tracer to estimate the hydraulic conductivity of canal bed sediment. Canal-leakage rates were estimated by applying Darcy's Law to modeled vertical hydraulic conductivity and either the estimated or measured hydraulic gradient. This approach will improve the understanding of the spatial and temporal variability of canal leakage in varying geologic settings identified in capacitively coupled resistivity surveys. The high-leakage potential study reach of the Tri-State Canal had two streamflow-gaging stations and two temperature monitoring sites along its length. Calculated leakage rates from the mass-balance approach varied from year to year and were generally dependent on local climatic conditions, and the timing and magnitude of the initial seasonal diversion into the Tri-State Canal. Leakage rates ranged from 0.98 meter per day (m/d) on June 22, 2007, to about to 0 m/d during July 2009. Drier conditions generally resulted in higher leakage rates because of reduced flow from Spottedtail Creek, lower groundwater levels near Spottedtail Creek, and no unmeasured flow entering the reach. Of the three years studied (2007-09), 2007 was the driest, and therefore had the highest canal leakage rates. The moderately low leakage potential study reach of Interstate Canal had two streamflow-gaging stations and one temperature monitoring site along its length. Excluding the leakage calculations from early May 2007, leakage rates ranged from 0.08 to 0.7 m/d. Less variability in leakage from year to year indicates that climatic conditions may have less of an effect for Interstate Canal compared to Tri-State Canal. This may be because Interstate Canal was cut into the northern edge of the North Platte alluvial valley and consequently the canal bed is well above the local groundwater table resulting in a constant (1 meter per meter [m/m]) hydraulic gradient. Interstate Canal also does not receive any captured flow that can vary substantially year to year. Two temperature monitoring sites were installed within the high-leakage potential reach of Tri-State Canal. Site TCTEMP1 was established in 2007 where the water table was well below the canal bed surface. The vertical hydraulic conductivity of the poorly sorted sand and gravel beneath site TCTEMP1 was estimated using a calibrated one-dimensional VS2DH model. Using a trial-and-error approach, the best-fit vertical hydraulic conductivity for the site TCTEMP1 model domain was 1.1 m/d. Site TCTEMP2 was established at the mouth of Spottedtail Creek where a shallow

Scientific Investigations Report↗
USGS2024

Recent applications of the USGS National Crustal Model for Seismic Hazard Studies

The U.S. Geological Survey is developing the National Crustal Model (NCM) for seismic hazard studies to facilitate modeling site, path, and source components of seismic hazard across the conterminous United States. The NCM is composed of a 1km grid of geophysical profiles, extending from the Earth’s surface into the upper mantle. It is constructed from a threedimensional (3D) geologic framework and geophysical rules that use (1) a petrologic and mineral physics database; (2) a 3D temperature model; and (3) a calibrated rock type- and age-dependent porosity model. Parameters needed to estimate site response for existing ground motion models (GMMs), including the time-averaged velocity in the upper 30 meters (VS30), the depths to 1.0 and 2.5 km/s shear-wave velocity (Z1.0 and Z2.5), and sediment thickness, can be computed from the NCM. As GMMs continue to improve in the future, other metrics could also be extracted or derived from the NCM, such as fundamental period, site attenuation (ko), a fully frequency-dependent site response function, or 3D geophysical volumes for wavefield simulations. Application of the NCM may also benefit other aspects of seismic hazard analysis, including better accounting for path-dependent attenuation and geometric spreading, more accurate estimation of earthquake source properties such as hypocentral location and stress drop, and calculation of crustal strength profiles that inform estimates of the base of seismicity.

conterminous United States↗
USGS1986

Geophysical maps of the Dos Cabezas Mountains Wilderness Study Area, Cochise County, Arizona

The Dos Cabezas Mountains Wilderness Study Area, Arizona, lies along part of the crest and northeast flank of the Dos Cabezas Mountains, Cochise County, near the southeast corner of Arizona (fig. 1). The U.S. Bureau of Land Management requested mineral surveys of about 11,921 acres of the approximately 15,000 acre wilderness study area. In this report "wilderness study area" refers to the 11,921 acres that were studied. The Dos Cabezas Mountains are in many ways a typical mountain range of the Basin-and-Range physiographic province. They are a northwest-trending block-faulted range separated from adjacent ranges by broad valleys. The range is about 22 mi long and 8 mi wide, and it reaches an elevation of 8,354 ft at Dos Cabezas Peaks, located about 2 mi west of the study area. The terrain of the area is rugged. Roadheads and trails provide adequate access for foot traverses. In the Dos Cabezas Mountains the Apache Pass fault zone is the major structural feature, barely skirting the southwest side of the study area. It extends several miles to the northwest and tens of miles to the southeast, across the Chiricahua Mountains beyond Apache Pass. It is typically made up of a pair of bounding faults and some anastomosing faults between them. The study area is underlain by a variety of sedimentary, igneous, and metamorphic rocks that provide only a fragmentary record of geologic events between Precambrian and Holocene times. A suite of metamorphic and igneous (primarily crystalline) rocks forms the basement terrain. Paleozoic and Mesozoic sedimentary rocks and also Paleozoic and Mesozoic volcanic rocks overlie the basement rocks but are extensively eroded away and may be covered. A pile of volcanic rocks of Late Cretaceous and Paleocene age caps the older rocks in much of the study area. Mid-Tertiary intrusive rocks underlie the eastern part of the study area as well as some very small, widely scattered additional localities. Quaternary gravel deposits occur in the major valleys and along the mountain front.

Arizona↗
USGS2014

Report of the committee on underground waters, 1938–39

In preparing the report of the Committee on Underground Waters of the Section of Hydrology for the final year of the triennium, it becomes evident that the collection of fundamental data relating to the hydrology of underground waters continues at a rate comparable to that maintained in the past few years, and perhaps even at an accelerated rate. Almost every extensive practical investigation of ground‐water supplies offers some opportunity for study of fundamental problems, in fact many of them require such fundamental study. With a larger number of investigations in progress, and with fairly liberal appropriations much new and valuable information is being discovered. Some idea of the increase in ground‐water studies since the organization of the Section of Hydrology may be given by a few statistics on the work of the Division of Ground‐Water of the Federal Geological Survey, which does the largest amount of ground‐water work in the United States. In 1932 the Division worked on about 50 projects in 25 States, in 15 of which and in Hawaii the investigations were made in cooperation with States, or other local Governmental agencies. During the current fiscal year work has been completed, or is in progress, on about 100 investigations in 35 States, Hawaii, and the Virgin Islands. The number of States cooperating on the work has increased to 24. During the current fiscal year about \$375,000 will be spent for ground‐water investigations by the Federal Geological Survey and cooperating organizations, as compared to about $175,000 spent during the fiscal year ended June 30, 1932.

Eos, Transactions, American Geophysical Union↗
USGS2002

Time‐lapse inversion of crosswell radar data

The combination of differential radar tomography with conventional tracer and/or hydraulic tests facilitates high‐resolution characterization of subsurface heterogeneity and enables the identification of preferential flow paths. In dynamic imaging, each tomogram is typically inverted independently, under the assumption that data sets are collected quickly relative to changes in the imaged property (e.g., attenuation or velocity); however, such “snapshot” tomograms may contain large errors if the imaged property changes significantly during data collection. Acquisition of less data over a shorter time interval could ameliorate the problem, but the resulting decrease in ray density and angular coverage could degrade model resolution. To address these problems, we propose a new sequential approach for time‐lapse tomographic inversion. The method uses space‐time parameterization and regularization to combine data collected at multiple times and to account for temporal variation. The inverse algorithm minimizes the sum of weighted squared residuals and a measure of solution complexity based on an a priori space‐time covariance function and a spatiotemporally variable mean. We demonstrate our approach using a synthetic 2‐D time‐lapse ( x , z , t ) data set based loosely on a field experiment in which difference‐attenuation radar tomography was used to monitor the migration of a saline tracer in fractured rock. We quantitatively show the benefits of space‐time inversion by comparing results for snapshot and time‐lapse inversion schemes. Inversion over both space and time results in superior estimation error, model resolution, and data reproduction compared to conventional snapshot inversion. Finally, we suggest strategies to improve time‐lapse cross‐hole inversions using ray‐based inversion constraints and a modified survey design in which different sets of rays are collected in alternating time steps.

Geophysics↗