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At least 1,225 records · Page 68Linked to original sources

USGS2007

A comparison of four geophysical methods for determining the shear wave velocity of soils

The Missouri Department of Transportation (MoDOT) routinely acquires seismic cone penetrometer (SCPT) shear wave velocity control as part of the routine investigation of soils within the Mississippi Embayment. In an effort to ensure their geotechnical investigations are as effective and efficient as possible, the SCPT tool and several available alternatives (crosshole [CH]; multichannel analysis of surface waves [MASW]; and refraction microtremor [ReMi]) were evaluated and compared on the basis of field data acquired at two test sites in southeast Missouri. These four methods were ranked in terms of accuracy, functionality, cost, other considerations, and overall utility. It is concluded that MASW data are generally more reliable than SCPT data, comparable to quality ReMi data, and only slightly less accurate than CH data. However, the other advantages of MASW generally make it a superior choice over the CH, SCPT, and ReMi methods for general soil classification purposes to depths of 30 m. MASW data are less expensive than CH data and SCPT data and can normally be acquired in areas inaccessible to drill and SCPT rigs. In contrast to the MASW tool, quality ReMi data can be acquired only in areas where there are interpretable levels of "passive" acoustic energy and only when the geophone array is aligned with the source(s) of such energy.

Environmental & Engineering Geoscience↗

USGS2018

Interaction between hydraulic fracture and a preexisting fracture under triaxial stress conditions

Enhanced reservoir connectivity generally requires maximizing the intersection between hydraulic fracture (HF) and preexisting underground natural fractures (NF), while having the hydraulic fracture cross the natural fractures (and not arrest). We have studied the interaction between a hydraulic fracture and a polished saw-cut fault. The experiments include a hydraulic fracture initiating from a pressurized axial borehole (using water) that approaches a dry fault that is inclined at an angle θ with respect to the borehole axis. The experiments are conducted on Poly(methyl) Meta Acrylate (PMMA) and Solnhofen limestone, a finely grained (<5 μm grain), low permeability (<10 nD) carbonate. The confining pressure in all experiments is 5 MPa, while the differential stress (1-80 MPa) and approach angle, θ (30, 45, 60, 90°) are experimental variables. During the hydraulic fracture, acoustic emissions (AE), slip velocity, slip magnitude, stress drop and pore pressure are recorded at a 5 MHz sampling rate. A Doppler laser vibrometer measures piston velocity outside the pressure vessel to infer fault slip duration and a strain gauge adjacent to the saw-cut provides a near-field measure of axial stress. For PMMA, the coefficient of friction was 0.30 and sliding was unstable (stick-slip). The approaching HF in PMMA created a tensile fracture detected by AE transducers ~100 μs before the significant stick-slip event (45% stress drop and slip velocity of ~60 mm/s) and was arrested by the fault at all fault orientations and differential stresses, even at 90° fault orientation and 80 MPa differential stress. For Solnhofen limestone, we observed stable sliding at a coefficient of friction of 0.12. In contrast to PMMA, the HF in Solnhofen consistently crossed to the other side of the fault. When the HF crossed the fault, it produced a small stress drop (<10%) and slip velocity of only 0.5 mm/s. Theoretical models by Blanton (1986) and Renshaw and Pollard (1995) predict that HF will be arrested for Solnhofen limestone and cross PMMA 90° fault at 80 MPa differential stress. Although the exact cause for the discrepancy between experiments and the theory is not known, one feature present in the experiments but not considered in the models, is the diffusion of fluid driven by the fault slip. Thus, the formation of a "fluid-filled patch" on the fault surface as it is intersected by the HF may substantially impact the crossing/arrest behavior. The approach angle and differential stress also influence the HF initiation azimuth and breakdown pressure. In most cases, the HF initiation azimuth was normal to the fault strike. These observations suggest that the presence of natural fractures could result in rotation of hydraulic fractures to be more normal to their strike and a subsequent change in the downhole pressure recordings. The latter could be used as a diagnostic tool for predicting this interaction.

Conference Paper↗

USGS2021

Intelligent monitoring system for real-time geologic storage, optimization, and reservoir management

The objective of the subtask was to develop a near-real-time monitoring system for seismic data at the Decatur, IL, geologic carbon sequestration (GCS) site and specifically include fiber-optic cable derived distributed acoustic signal (DAS) data in the process. Owing to the large volumes of data, we opted to utilize existing deep borehole conventional seismic sensors for detection and pull DAS and shallow borehole seismic data once a detection has been made. Unfortunately, the horizontal fiber-optic cables did not yield microseismic signals for use in locating events near the GCS site. Various stacking and filtering approaches were tested without any coherent detection becoming apparent. We attribute the insensitivity to local microseismic events to a lack of coupling in downhole, vertical cable and the non-ideal alignment of the horizontal fiber-optic cable to the vertically polarized seismic energy. Despite the inability to detect and utilize the DAS data from the fiber-optic cables, we developed a general processing framework that enables easy adaptation for future deployment of fiber-optic cables with better suited alignment at Decatur or elsewhere.

Technical Report↗

USGS2016

Wind energy development: Methods for assessing risks to birds and bats pre-construction

Wind power generation is rapidly expanding. Although wind power is a low-carbon source of energy, it can impact negatively birds and bats, either directly through fatality or indirectly by displacement or habitat loss. Pre-construction risk assessment at wind facilities within the United States is usually required only on public lands. When conducted, it generally involves a 3-tier process, with each step leading to more detailed and rigorous surveys. Preliminary site assessment (U.S. Fish and Wildlife Service, Tier 1) is usually conducted remotely and involves evaluation of existing databases and published materials. If potentially at-risk wildlife are present and the developer wishes to continue the development process, then on-site surveys are conducted (Tier 2) to verify the presence of those species and to assess site-specific features (e.g., topography, land cover) that may influence risk from turbines. The next step in the process (Tier 3) involves quantitative or scientific studies to assess the potential risk of the proposed project to wildlife. Typical Tier-3 research may involve acoustic, aural, observational, radar, capture, tracking, or modeling studies, all designed to understand details of risk to specific species or groups of species at the given site. Our review highlights several features lacking from many risk assessments, particularly the paucity of before-and-after-control- impact (BACI) studies involving modeling and a lack of understanding of cumulative effects of wind facilities on wildlife. Both are essential to understand effective designs for pre-construction monitoring and both would help expand risk assessment beyond eagles.

Human-Wildlife Interactions↗

USGS1984

Geologic evolution, sedimentation, and paleoenvironments of the Angola Basin and adjacent Walvis Ridge: Synthesis of results of Deep Sea Drilling Project Leg 75

The section recovered at Site 530 (Holes 53OA and 530B) consists of eight sedimentary units and one basalt unit. The composition of the basalt recovered in Hole 53OA is distinct from typical mid-ocean ridge basalts (MORBs) but is similar to that of Hawaiian tholeiites and basalt from the central part of Walvis Ridge. Throughout most of its history, the southern Angola Basin received large volumes of redeposited material in the form of turbidites and, most recently, debris-flow deposits. Most of this material was derived from Walvis Ridge to the south, but thickness trends of acoustic units suggest that some of the sediment was derived from the African continental margin to the east. The basal sedimentary unit (Albian to Santonian) at Site 530 contains 262 beds of black shale that are interbedded with green and red claystone. Black shale makes up less than 10% of the total section, but in two cores of early Turonian age, black shale beds compose about 50% of the section. The black shales contain up to 19% organic carbon (average of about 5%) that is mainly of autochthonous marine origin but with significant contributions from terrigenous organic matter. The origin of these more- and less-reduced interbedded lithologies with varying amounts and types of organic matter, and variable amounts of pelagic, hemipelagic, and turbiditic sediment is complex and cannot be explained by any one simple process. Many factors affecting the concentration of dissolved oxygen in the bottom waters of the Angola Basin varied throughout the middle Cretaceous to produce bottom-water conditions that fluctuated between mildly oxic and oxygen-deficient, but most of the time bottom-waters and sediment-interstitial waters were sufficiently oxic to permit the accumulation of red oxidized sediment. A relatively complete sedimentary record of the Cretaceous/Tertiary boundary was recovered within a sequence of mudstone and marlstone turbidites in Hole 530A. There is a significant increase in the concentration of iridium above background levels at the boundary. High concentrations of many other elements also occur within the same stratigraphic interval as the iridium anomaly. Furthermore, there is a marked decrease in CaCO3 in the Tertiary strata above the iridium anomaly which suggests that the production of shallow-water carbonate also may have been affected by whatever caused elevated concentrations of iridium and other elements. These observations are consistent with the asteroid-impact theory proposed to explain the worldwide occurrence of an iridium anomaly at the Cretaceous/Tertiary boundary. The Cenozoic history of the Angola Basin was controlled mainly by (1) restriction of bottom-water flow from the south by Walvis Ridge; (2) development of glaciation on Antarctica; (3) opening of circulation passages in the southern oceans; (4) rapid turnover of cold, nutrient-rich waters that resulted in high productivity of diatoms; (5) influx of terrigenous sediment mainly by turbidity currents; and (6) production and preservation of carbonate sediment. The most distinctive Cenozoic event recorded in the section at Site 530 is the beginning of extensive glaciation on Anarctica and concomitant initiation of modern thermohaline bottom-water circulation that is manifested as a middle Eocene to middle Oligocene unconformity or compressed section accompanied by a drastic decrease in accumulation of CaCO3. Diatom abundances in HPC cores from Walvis Ridge (Site 532) and Angola Basin (Hole 53OB) indicate that Benguela upwelling in these areas began in the late Miocene, reached a peak in the late Pliocene to early Pleistocene, and declined thereafter. Short-term variations in sediment composition at Site 532 are manifested as cyclic variations in concentrations of clay, CaCO3, and organic carbon with average periodicities of about 30-60 k.y. The main variability that produced the cycles probably was the influx of terrigenous clastic material which diluted the CaCO3. The sediment at Site 532 also contains several percent organic carbon that is dominantly of marine origin, but with significant terrigenous components. Data from multichannel seismic, gravity, and magnetic surveys were used to define the regional stratigraphic and structural evolution of Walvis Ridge and adjacent Cape and Angola basins. Six structural provinces are recognized, four on Walvis Ridge and two additional provinces that correspond to the Cape and Angola basins. The two eastern structural provinces on Walvis Ridge are underlain by continental crust. The two western structural provinces are underlain by oceanic basement. Two main directions of faults are evident in seismic profiles, one trending N 10° and one trending N 60°. The N 60° trend corresponds to the general orientation of the northern and southern flanks of Walvis Ridge as well as to the dominant direction of fracture zones. During the first phase of separation of Africa from South America (ca. 120-130 m.y. ago), a voluminous mass of volcanics was emplaced simultaneous with the emplacement of basalt in the Parana Basin of Brazil and the Kaokoveld Region of South Africa. This period of volcanism also formed the series of seaward-dipping internal basement reflectors that are characteristic of the two structural provinces of Walvis Ridge. A system of fault blocks developed in the brittle upper part of the newly formed crust. During the second phase of rifting, which ended before late Aptian, more tilted fault blocks were created in the upper brittle stratified continental crust. Magnetic lineations in basement rocks in the Angola and Cape basins in the vicinity of Walvis Ridge are not distinct but suggest that oceanic crust began to be emplaced between 120 and 112 m.y. ago (Barremian to early Aptian). At least part of the oceanic crust of the central plateau of eastern Walvis Ridge (structural province 3) may have been emplaced before any oceanic crust formed in the adjacent basins. A ridge jump occurred during the late Aptian to early Albian in the southern part of the Angola Basin which translated the previously formed oceanic crust and its overlying evaporite deposits on the South American side. Several ridge jumps occurred on both sides of Walvis Ridge during the Late Cretaceous and early Tertiary to produce a 500-km-long segment of mid-ocean ridge.

Initial Reports of the D.S.D.P.↗

USGS1990

Gas hydrates of the Peruvian outer continental margin

Gas hydrates were recovered during coring by Ocean Drilling Program (ODP) Leg 112 at Sites 685 and 688 on the Peruvian outer continental margin at latitudes of 9° and 11.5°S, where water depths are 5070 and 3820 m, respectively. In addition, nearby Sites 682 and 683 yielded compelling evidence that gas hydrates are present, but gas hydrates were not directly observed there. Anomalous acoustic reflectors, known as bottom-simulating reflectors (BSRs), on marine seismic profiles from the region also provided inferential evidence that gas hydrates are present. Geothermal gradients of about 43 and 49°C/km were calculated on the basis of relations between depths to BSRs, bottom-water temperatures, and the pressure-temperature stability field of gas hydrates. Geochemical studies revealed that methane concentrations increase rapidly with depth after pore-water sulfate concentrations have been depleted. The relationship between methane and sulfate suggests that microbial processes account for the generation of methane, and the relationship between the carbon isotopic composition of methane and dissolved carbon dioxide supports this suggestion. We believe that decreasing chlorinity in pore water from squeezed sediment at the four sites results mainly from the decomposition of gas hydrates and is a dilution artifact observed as a result of the squeezing procedure. Maximum chlorinity values at or near the surface result from excess salt that comes from the formation of gas hydrates composed of freshwater. Record alkalinity attests to the intensity of diagenetic processes and has significant effects on salinity profiles at these sites. Gas hydrates were recovered at 99 and 166 meters below the seafloor (mbsf) at Site 685, and at 141 mbsf at Site 688 in Pleistocene diatomaceous mud. Methane constitutes more than 99% of the hydrocarbon gas mixture in the gas hydrates. The volumetric ratio of methane to water in the sample from Site 685 is 100, indicating that the sampled gas hydrate is either undersaturated with respect to methane or had partially decomposed during core recovery or both. The discovery of gas hydrates in lower slope deposits of the Peruvian outer continental margin extends our knowledge of gas-hydrate formation and occurrence in the Circum-Pacific region.

ODP Leg 112↗

USGS1991

Sonobuoy seismic studies at ODP drill sites in Prydz Bay, Antarctica

Five sonobuoy seismic-refraction records were collected along the Leg 119 geophysical transect across the Prydz Bay shelf. Velocity-depth profiles are computed from the sonobuoy data and are used to produce a depth section for the principal acoustic unit boundaries observed in the seismic-reflection data along the transect. Traveltime curves generated by ray-tracing for models constructed from downhole velocity logs are compared to curves generated for models based solely on the sonobuoy data. This comparison reveals that sonobuoy data are less reliable for analysis of lithostratigraphy in vertically and laterally complex areas; however, the sonobuoy data can be used to accurately estimate the depth to a specific horizon in the reflection data to within 10 m. Near-surface velocities exceed 2.0 km/s at all sites, indicating likely overconsolidation of sediments due to glacial loading and erosion during periods of grounded ice sheets on the shelf. Sedimentary rock velocities exclusively were observed beneath the shelf to depths of 3 km. At the landward site a deep refraction is observed with a velocity and vertical gradient indicative of basement rock.

Conference Paper↗

USGS2004

Seismic stratigraphic correlations between ODP sites 742 and 1166: Implications for depositional paleoenvironments in Prydz Bay, Antarctica

New high-resolution seismic reflection data recorded between Ocean Drilling Program Sites 1166 and 742 are interpreted to link acoustic features to lithologic units at the two drill sites. New findings include: (1) Site 1166 drilled a deeper (older) section than Site 742; (2) Paleogene units mostly do not extend between the two sites, except the deformed sand unit (Units III [1166] and VI [742]); (3) the preglacial to glacial unconformity sampled at Site 1166 lies ~50 m below Site 742; (4) the Paleogene flooding surface at Site 1166 lies on top of Unit III, not within, as previously reported; and (5) Pliocene diatomaceous horizons correlated between the sites based on downhole logging cannot be traced between the two sites in seismic data. For the study region, we infer a progression from a preglacial setting on a low-relief alluvial plain to glaciomarine and subglacial settings. Late Cretaceous alluvial plain and lagoonal environments evolved to a late Eocene broad fluvial channel system or outwash plain. Marine transgression infilled and buried the channel system with glacial deposits that were extensively eroded during the Oligocene to late Miocene. Late Neogene environments were mostly subglacial with episodes of reduced ice and biogenic deposition.

Proceedings of the Ocean Drilling Program: Scienti↗

USGS2020

Distribution and transport of Olympia oyster, Ostrea lurida, larvae in northern Puget Sound, Washington, USA

As efforts for restoring Olympia oyster (Ostrea lurida) populations have expanded, there is an increased need to understand local factors that could influence the long-term success of these projects. To address concerns over potential limitations to recruitment at a restoration site in northern Puget Sound, Washington, USA, a study was developed to characterize physical processes governing larval transport in conjunction with larval abundance and environmental factors. Larval presence was not associated with tide cycle, season, or a combination of tide cycle and season. In terms of location, larvae were more likely to be present at offshore and intertidal sites versus the estuarine lagoon where the adult population resides. Larval density was higher during late summer ebbs versus early summer floods. Across sampling dates and locations, larval sizes ranged from 184 to 263 µm, indicating that larvae were released into the water column throughout the reproductive season and retained in the embayment for at least ~16 days. Throughout different tidal cycles in Skagit Bay, acoustic Doppler current profilers were used to measure current direction and velocities, concurrent with plankton sampling. Surface currents in the study area alternated between a clockwise and counterclockwise gyre during initial ebb and flood tides, respectively. Larvae exported from the source population during initial to mid-ebbs are swept into a northward gyre, and potentially retained at intertidal sites alongshore. These results will provide resource managers attempting to restore native bivalves with the ability to expand populations by identifying optimal areas for habitat enhancement through natural recruitment.

Washington↗

USGS2023

Landscape configuration influences Oma‘o (Myadestes obscurus) song diversity

Acoustic communication in the form of songs is a learned behavior in oscine that can be passed down from one generation to the next through cultural transmission. Over time songs can change when populations become isolated from one another, creating dialects that are distinct to a population. Habitat fragmentation is an isolating mechanism that can influence differences in songs between populations when there is little to no connectivity between fragments and fragment size can influence diversity of song traits. We characterized and analyzed songs of the ‘ōma‘o ( Myadestes obscurus ) in a naturally fragmented forest to determine how landscape variables influenced song differences between populations. We chose five fragments of different sizes and isolation to record songs of the ‘ōma‘o. We performed a correlation test to evaluate whether there was a relationship between fragment size and total syllables, and between unique syllables and degree of isolation. We also conducted a Mantel test to determine if geographic distance had an influence on song similarity. Our results indicated that songs from larger fragments tended to have higher syllable diversity, but neither connectivity nor distance was related to the number of unique or shared syllables found within a fragment, respectively. Overall, the results indicated that ‘ōma‘o songs are highly variable at the individual level and that there may be little to no syllable sharing within and among populations.

Hawaii↗

USGS2026

Samoa basin abyssal mapping: Box coring leg

This cruise report describes work from leg three of the NOAA American Samoa Abyssal Mapping effort, OPR-T900-KR-26. Leg one preceded this effort and collected ship-based acoustic data. Leg two collected autonomous underwater vehicle (AUV) data and began before, continued contemporaneously, and finished subsequently to leg three. The USGS field activity number assigned to this expedition is 2026-604-FA. The objective of this expedition was to collect representative box cores to inform prospectivity analyses through the region, and co-located interdisciplinary datasets as practical. USGS personnel directed the sampling locations and took custody of the box cores once recovered shipboard. USGS personnel then photographed and described the cores, subsampled, conducted analyses including wet weights and time sensitive measurements, and preserved subsamples and additional components for future work. Data releases co-released with this report are listed in the section “paired data releases.” NOAA released data from all legs of this effort in near-real time. Details of the preceding legs, the data, and NOAA’s project summary available from NOAA, (2026). This report is an expedition summary with preliminary datasets; remaining data releases and publications will be forthcoming.

EarthArXiv↗

USGS2010

Two-dimensional hydrodynamic modeling to quantify effects of peak-flow management on channel morphology and salmon-spawning habitat in the Cedar River, Washington

The Cedar River in Washington State originates on the western slope of the Cascade Range and provides the City of Seattle with most of its drinking water, while also supporting a productive salmon habitat. Water-resource managers require detailed information on how best to manage high-flow releases from Chester Morse Lake, a large reservoir on the Cedar River, during periods of heavy precipitation to minimize flooding, while mitigating negative effects on fish populations. Instream flow-management practices include provisions for adaptive management to promote and maintain healthy aquatic habitat in the river system. The current study is designed to understand the linkages between peak flow characteristics, geomorphic processes, riverine habitat, and biological responses. Specifically, two-dimensional hydrodynamic modeling is used to simulate and quantify the effects of the peak-flow magnitude, duration, and frequency on the channel morphology and salmon-spawning habitat. Two study reaches, representative of the typical geomorphic and ecologic characteristics of the Cedar River, were selected for the modeling. Detailed bathymetric data, collected with a real-time kinematic global positioning system and an acoustic Doppler current profiler, were combined with a LiDAR-derived digital elevation model in the overbank area to develop a computational mesh. The model is used to simulate water velocity, benthic shear stress, flood inundation, and morphologic changes in the gravel-bedded river under the current and alternative flood-release strategies. Simulations of morphologic change and salmon-redd scour by floods of differing magnitude and duration enable water-resource managers to incorporate model simulation results into adaptive management of peak flows in the Cedar River. PDF version of a presentation on hydrodynamic modelling in the Cedar River in Washington state. Presented at the American Geophysical Union Fall Meeting 2010.

Washington↗

USGS2009

2008 Spawning Cisco Investigations in the Canadian Waters of Lake Superior

The Great Lakes Science Center of the United States Geological Survey (USGS) is working cooperatively with the Ontario Ministry of Natural Resources (OMNR) on a threeyear study to develop standard procedures for acoustic and midwater trawl (AC-MT) assessments of spawning cisco Coregonus artedi that the OMNR can carry forward as a management activity. In year two (2008), we conducted an AC-MT survey of the northern shore from Nipigon Bay to Thunder Bay. Spawning-cisco (> 250 mm total length) densities were lowest near Nipigon Bay (<10/ha), moderate in and around Black Bay (15- 30/ha), and highest in Thunder Bay (118/ha). Rainbow smelt Osmerus mordax densities were highest in Nipigon (2,179/ha) and Black (3,219/ha) bays, and lowest in Thunder Bay (961/ha). We combined our AC-MT survey results with commercial catch records to estimate exploitation fractions of female cisco in Thunder Bay during the 2008 fishery at 4% for ages 1-5, 8.7% for ages 6-12, and 4.4% for ages ≥ 13. Lake Superior fishery managers recently recommended that annual exploitation of adult female lake cisco be kept below 10-15%. Recruitment of cisco since 2003 has been low and there is a strong probability the Thunder Bay stock will decline into the future. Using a simple population dynamics approach we estimated that if the current total allowable catch (TAC) quota is held constant, exploitation fractions could exceed 10% by 2010 and 15% by 2011. Our 2008 collections suggested the survey of Black Bay was likely conducted before all spawners had returned there to spawn. Our data also suggested that cisco collected in Black Bay and east of this site in mid-November may be from the same stock. During November 2009 we will attempt to get better definition of the area occupied by cisco around Black Bay and also determine when surveys should be conducted at this location.

Report↗

USGSDate not supplied

Seafloor images refine petroleum exploration models

Acoustic mapping of the EEZ sea floor using GLORIA side-scan sonar tool includes the margins of the continental United States, Alaska, Hawaii, and Johnston Island. This decade-long program was undertaken in cooperation with the United Kingdom's Institute of Oceanographic Sciences at the Deacon Laboratory (now the Southampton Oceanography Centre).

Report↗

USGS1997

Use of remote-sensing techniques to survey the physical habitat of large rivers

Remote-sensing techniques that can be used to quantitatively characterize the physical habitat in large rivers in the United States where traditional survey approaches typically used in small- and medium-sized streams and rivers would be ineffective or impossible to apply. The state-of-the-art remote-sensing technologies that we discuss here include side-scan sonar, RoxAnn, acoustic Doppler current profiler, remotely operated vehicles and camera systems, global positioning systems, and laser level survey systems. The use of these technologies will permit the collection of information needed to create computer visualizations and hard copy maps and generate quantitative databases that can be used in real-time mode in the field to characterize the physical habitat at a study location of interest and to guide the distribution of sampling effort needed to address other habitat-related study objectives. This report augments habitat sampling and characterization guidance provided by Meador et al. (1993) and is intended for use primarily by U.S. Geological Survey National Water Quality Assessment program managers and scientists who are documenting water quality in streams and rivers of the United States.

Report↗

USGS2016

Characterization of fractures and flow zones in a contaminated crystalline-rock aquifer in the Tylerville section of Haddam, Connecticut

The U.S. Geological Survey, in cooperation with the Connecticut Department of Energy and Environmental Protection, investigated the characteristics of the bedrock aquifer in the Tylerville section of Haddam, Connecticut, from June to August 2014. As part of this investigation, geophysical logs were collected from six water-supply wells and were analyzed to (1) identify well construction, (2) determine the rock type and orientation of the foliation and layering of the rock, (3) characterize the depth and orientation of fractures, (4) evaluate fluid properties of the water in the well, and (5) determine the relative transmissivity and head of discrete fractures or fracture zones. The logs included the following: caliper, electromagnetic induction, gamma, acoustic and (or) optical televiewer, heat-pulse flowmeter under ambient and pumped conditions, hydraulic head data, fluid electrical conductivity and temperature under postpumping conditions, and borehole-radar reflection collected in single-hole mode. In a seventh borehole, a former water-supply well, only caliper, fluid electrical conductivty, and temperature logs were collected, because of a constriction in the borehole. This report includes a description of the methods used to collect and process the borehole geophysical data, the description of the data collected in each of the wells, and a comparison of the results collected in all of the wells. The data are presented in plots of the borehole geophysical logs, tables, and figures. Collectively these data provide valuable characterizations that can be used to improve or inform site conceptual models of groundwater flow in the study area.

Connecticut↗

USGS2006

Water-Quality Data for the Lower Russian River Basin, Sonoma County, California, 2003-2004

In 2003, the U.S. Geological Survey, in cooperation with the Sonoma County Water Agency, began a study to determine the chemical, microbiological, and isotopic composition of the surface water and ground water in selected areas of the Lower Russian River Basin, Sonoma County, California. This report is a compilation of the hydrologic and water-quality data collected from 10 Russian River sites, 1 gravel-terrace pit site, 12 ground-water sites, 11 tributary sites including Mark West Creek, and 2 estuary sites between the city of Healdsburg and the Pacific Ocean, for the period August 2003 to September 2004. Field measurements made included streamflow, barometric pressure, dissolved oxygen, pH, specific conductance, and turbidity. Water samples were analyzed for nutrients, major ions, total and dissolved organic carbon, trace elements, mercury, wastewater compounds, total coliform, Escherichia coli, Enterococci, Clostridium perfringens, and the stable isotopes of hydrogen and oxygen. Discharge measurements and sampling techniques were modified to accommodate the very low summer flows at most of the tributaries, and discharge measurements were made with an acoustic Doppler velocity meter at the estuary river site to overcome the complexities associated with tidal influences.

Data Series↗

USGS2006

Cross-Sectional Data for Selected Reaches of the Chattahoochee River within the Chattahoochee River National Recreation Area, Georgia, 2004

This report presents hydrologic data for selected reaches of the Chattahoochee River within the Chattahoochee River National Recreation Area (CRNRA). Data about transect location, width, depth, and velocity of flow for selected reaches of the river are presented in tabular form. The tables contain measurements collected from shoal and run habitats identified as critical sites for the CRNRA. In shoal habitats, measurements were collected while wading using a digital flowmeter and laser range finder. In run habitats, measurements were collected using acoustic Doppler current profiling. Fifty-three transects were established in six reaches throughout the CRNRA; 24 in shoal habitat, 26 in run habitat, and 3 in pool habitat. Illustrations in this report contain information about study area location, hydrology, transect locations, and cross-sectional information. A study area location figure is followed by figures identifying locations of transects within each individual reach. Cross-sectional information is presented for each transect, by reach, in a series of graphs. The data presented herein can be used to complete preliminary habitat assessments for the Chattahoochee River within the CRNRA. These preliminary assessments can be used to identify reaches of concern for future impacts associated with continual development in the Metropolitan Atlanta area and potential water allocation agreements between Georgia, Florida, and Alabama.

Georgia↗