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DC Resitivity Methodology Direct current (DC) resistivity transects were surveyed using an IRIS Syscal Pro Switch 96 instrument (IRIS Instruments, Inc., Orléans, France). Steel electrodes were hammered into the ground at a fixed distance along the profile. These were connected to the instrument using copper wires and junction boxes. The number of electrodes on each profile and their spacing is shown below: Line 1: 180 electrodes, 5 meter spacing Line 2: 48 electrodes, 2 meter spacing Line 3: 48 electrodes, 2 meter spacing Line 4: 24 electrodes, 2 meter spacing Line 5: 36 electrodes, 2 meter spacing On Line 1, the roll-along method was used to extend the line to its full extent. In this method, 48 electrodes...
Categories: Data
Lake Poinsett is a 260-hectare (640 acres) lake located on Crowley’s Ridge in northeastern Arkansas, approximately 6 km southeast of Harrisburg, Arkansas within Poinsett County. The lake was built for recreation by the Arkansas Highway Department in 1960 by constructing a roughly 800-meter dam across the southern boundary of the Distress Creek watershed. The dam is currently operated by the Arkansas Game and Fish Commission (AGFC). AGFC and Arkansas Natural Resources Commission (ANRC) plan to drain the lake to allow access for a series of bank stabilization and dam safety improvements. Because none of the original blueprints exist, AGFC asked the U.S. Geological Survey (USGS) to conduct a series of differential...
Categories: Data;
Tags: Arkansas,
Crowley's Ridge,
Electrical Resistivity,
Frequency Domain Electromagnetics,
GNSS Survey,
FDEM Methodology For this project frequency domain electromagnetic (FDEM) data were collected with a GEM-2, a broadband, multifrequency, fixed-coil electromagnetic induction unit (Geophex, 2015). Both in-phase and quadrature data were collected on 15 channels from a frequency of 810 Hz to 66,090 Hz. This system was carried along profiles that followed the axis of the dam and along tie lines that were perpendicular to the axis of the dam. Each data point was located using a backpack mounted GPS. To correct the drift of the instrument, a base station was established on the east side of the dam. Each survey started and ended with an occupation of the base station. These occupations occur as even line numbers...
Categories: Data
The availability of groundwater-quality data for relatively deep wells (wells generally more than 300 feet deep) containing saline water (dissolved-solids concentrations greater than 2,000 milligrams per liter) is limited throughout the state of Texas. Water-quality samples are important for calibrating estimates of groundwater salinity derived from geophysical well logs. Water-quality data collected in 2021 from four wells completed in selected aquifers (Trinity, Carrizo-Wilcox, and Yegua-Jackson) in Texas are included in this data release.
This data release contains waterborne gradient self-potential (SP), surface-water temperature, surface-water conductivity and specific conductance, and surface-water nitrate concentration data measured continuously in the upper part of the Delaware River along approximately 123 kilometers (km) between Hancock and Port Jervis, New York. All of the data were measured from a kayak between June 27 and July 2, 2021. Gradient self-potential data were measured along five survey segments that varied in length between 13.1 and 31.6 km. The first segment began at Hancock, N.Y. on the east branch of the Delaware River, progressed into the main stem, and ended about 13.1 river-km downstream in Lordville, N.Y. at U.S. Geological...
Categories: Data;
Tags: Barryville, New York,
Callicoon, New York,
Geophysical logging,
Geophysics,
Geophysics,
More than 11,500 well records, such as geophysical logs, drilling descriptions, and published hydrogeologic framework information, were evaluated to help characterize the framework of hydrogeologic units in and near Gaines, Terry, and Yoakum Counties, Texas. Additional geophysical data were collected to improve the spatial coverage across the study area and to reduce uncertainty with regard to hydrogeologic unit extents. The evaluation of existing data plus the collection of new geophysical data provided that basis for developoing a refined understanding of how the saturated thickness of the Ogallala and Edwards-Trinity aquifers vary throughout the study area.
Declining groundwater levels in and near Gaines, Yoakum, and Terry Counties in the Texas Panhandle have raised concerns about the amount of available groundwater and the potential for water-quality changes resulting from dewatering and increased vertical groundwater movement between adjacent water-bearing hydrogeologic units. More than 9,800 well records, such as geophysical logs, drilling descriptions, and published hydrogeologic framework information, were evaluated to help characterize the framework of hydrogeologic units in the study area. Additional geophysical data were collected to improve the spatial coverage across the study area and to reduce uncertainty with regard to hydrogeologic unit extents. Of greatest...
In May 2021, the U.S. Geological Survey, in cooperation with the U.S. Army Corps of Engineers, logged 9 previously drilled boreholes in the bedrock beneath Bull Shoals Dam with acoustic and optical televiewer geophysical methods. The acoustic and optical televiewer logging results were used to identify fractures and small bedding planes in the bedrock beneath the dam using the image and structure interpretation module of Well CAD (v.5.4). This data release consists of each geophysical log in standard log American Standard Code for Information Interchange (ASCII) text (.las) format and a comma separated (.csv) file detailing the fracture and bedding plane analysis completed on each geophysical log.
The hydrogeology of the Cannon Air Force Base (AFB) in Curry County, is being investigated to better understand the mechanics of groundwater flow in the area, including the identification of preferential groundwater flow paths. Mapping the top of the Dockum Group was done to help identify potential paleochannels that may have eroded the surface of the Dockum Group and subsequently filled in with coarse-grained sediments of the overlying Ogallala Formation. The Dockum Group is composed of sandstone, siltstone, mudstone, and shale that were originally deposited in fluvial and lacustrine environments (McGowen and others, 1979). The upper part of the Dockum Group is a thick layer of red clay referred to locally as the...
GNSS Method A benchmark monument was set at each end of the earthen dam in accordance with (U.S. Army Corps of Engineers, 2002). A level II survey (Rydlund & Densmore 2012) was conducted on each monument to establish control. Two 4-hour observations were conducted with a staggered approach for each monument, with one 4-hour session in the morning of the first day and one 4-hour session in the afternoon of the second day. Once elevational control was established, a Real Time Kinematic (RTK) system was set up with base on the monument that had the best observations. Using this system, a point cloud survey was conducted along the top and face of the dam using both a monopod and an All-Terrain Vehicle. A Global...
Categories: Data
FDEM Processing The frequency domain electromagnetic (FDEM) data were downloaded from the GEM-2 instrument and aggregated into a single data file. The data were manually despiked and smoothed to remove negative values and the effects of metallic objects. A drift correction was applied by finding the average in-phase and average quadrature values for each frequency transmitted each time the base station was occupied. This average value was then used to calculate a linear trend of the data in time and the linear trend was subtracted from the data set. After the data were drift corrected, the data was leveled by calculating the arithmetic mean of the survey data subtracting that value from the dataset to level...
Categories: Data
In cooperation with more than 10 local, State, and Federal stakeholders, the United States Geological Survey (USGS) is studying the aquifer systems in and near the Mississippi River alluvial plain (https://www2.usgs.gov/water/lowermississippigulf/map/index.html). This data release consists of continuous resistivity profiling (CRP) data collected by the USGS to characterize the electrical properties of geomorphological features in the part of the Mississippi River alluvial plain from Money, Miss. to Steiner, Miss. A total of 68 kilometers of multiple CRP profiles were obtained. The CRP data were collected by using the Ohmmapper TR-5 system (Geometrics, Inc., 2016) to determine if different geomorphological features...
Categories: Data;
Types: ArcGIS REST Map Service,
ArcGIS Service Definition,
Downloadable,
Map Service;
Tags: Continuous Resistivity Profiling,
Geomorphology,
Geophysics,
Geophysics,
Greenville,
This data release consists of three different types of data: including direct current (DC) resistivity profiles, frequency domain electromagnetic (FDEM) survey data, and global navigation satellite system (GNSS) coordinate data of the geophysical measurement locations. A data dictionary is included along with the data and defines all of the table headings, definitions, and units. Earthen dams are common on lakes and ponds, but characteristics of these structures such as construction history, composition, and integrity are often unknown for older dams. Geophysical surveying techniques provide a non-invasive method of mapping their lithology and structure. In particular, DC resistivity and FDEM methods can,...
Categories: Data;
Tags: Arkansas,
Bob Kidd Lake,
Direct current resistivity,
Earthen dam,
Earthen structure,
FDEM Methodology For this project frequency domain electromagnetic (FDEM) data were collected with a GEM-2, a broadband, multifrequency, fixed-coil electromagnetic induction unit (Geophex, 2015). Both in-phase and quadrature data were collected on 15 channels from a frequency of 810 Hz to 66,090 Hz. This system was carried along profiles that followed the axis of the dam and along tie lines that were perpendicular to the axis of the dam. Each data point was located using a backpack mounted GPS. To correct the drift of the instrument, a base station was established on the east side of the dam. Each survey started and ended with an occupation of the base station. These occupations occur as even line numbers...
Categories: Data
This data release contains self-potential (SP), electrical resistivity tomography (ERT), and water temperature and conductivity data measured during a geophysical survey at the Krause Springs property in Spicewood, Texas. The geophysical survey was completed February 4–15, 2019, over approximately 3.1 acres on the western side of the property adjacent to the main visitor parking lot and entrance facilities. SP data were measured on the land surface within the survey area to locate SP anomalies attributed to groundwater flow. The locations and spatial distribution of the discovered SP anomalies were used to orient four ERT profiles to intersect the SP anomalies. Two ERT profiles, consisting of 84 stainless steel...
Categories: Data;
Tags: Electrical resistivity tomography,
Geophysics,
Groundwater,
Hydrology,
Krause Springs,
This data release contains time-lapse self-potential, electric resistivity tomography, hydrographic, and weather data acquired during a geoelectric monitoring survey of the lower Rio Grande riverbed in the Mesilla Basin of southeast, New Mexico. The monitoring survey was performed by the U.S. Geological Survey (USGS) in cooperation with New Mexico State University (NMSU), Elephant Butte Irrigation District (EBID), and hydroGEOPHYSICS, Inc (HGI). The data and corresponding data processing codes are described in the larger work citation, a journal article titled "Geoelectric Monitoring of the Electric-potential Field of the Lower Rio Grande Before, During, and After Intermittent Streamflow, May-October, 2022." The...
Declining groundwater levels in the Hueco Bolson have raised concerns about the amount of available groundwater and the potential for water-quality changes. Fresh groundwater stored in the aquifer is bordered by regions of brackish-to-saline groundwater, and as the water levels in the Hueco Bolson have declined the local and regional hydraulic gradients have been altered such that the brackish-to-saline groundwater regions have encroached upon and degraded the quality of the freshwater zones (Hibbs 1999; Heywood and Yager, 2003). To help delineate the freshwater and saline groundwater transition zone, 20 time-domain electromagnetic soundings were collected to provide resistivity structure data in the area. This...
DC Resitivity Methodology Direct current (DC) resistivity transects were surveyed using an IRIS Syscal Pro Switch 96 instrument (IRIS Instruments, Inc., Orléans, France). Steel electrodes were hammered into the ground at a fixed distance along the profile. These were connected to the instrument using copper wires and junction boxes. The number of electrodes on each profile and their spacing is shown below: Line 1: 180 electrodes, 5 meter spacing Line 2: 48 electrodes, 2 meter spacing Line 3: 48 electrodes, 2 meter spacing Line 4: 24 electrodes, 2 meter spacing Line 5: 36 electrodes, 2 meter spacing On Line 1, the roll-along method was used to extend the line to its full extent. In this method, 48 electrodes...
Categories: Data
Groundwater-quality data and geophysical information for relatively deep wells (wells generally more than 300 feet deep) containing saline water (dissolved-solids concentrations greater than 2,000 milligrams per liter) are limited throughout the state of Texas. Information derived from geophysical well logs can be used to estimate groundwater salinity. Geophysical logs were collected in 2021 from 10 of the 12 wells completed in selected aquifers (Trinity, Edwards-Trinity (Plateau), Carrizo-Wilcox, Sparta, and Yegua-Jackson) in Texas.
Categories: Data;
Tags: Bandera County,
Blanco County,
Carrizo-Wilcox aquifer,
Edwards-Trinity aquifer,
Gonzales County,
DC Resistivity Processing Data were imported into the Workbench Electrical Resistivity Tomography Module (Aarhus Geophysical, Inc.; version 5.5.0.0) using the “Syscal” data import options. The data were then manually despiked and any negative resistivity values were removed. The data were subsequently inverted using “Aarhus 2D” inversion option. The “Smooth” Inversion setting was chosen with model converging to the L2 norm. The number of layers of the starting model was set to 20. The vertical model discretization was set to the default for each given combination of line length and electrode spacing. The starting value was set to “Auto”. The lateral and vertical constraints were set to the “Medium” settings....
Categories: Data
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