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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 973 records · Page 54Linked to original sources
USGS1986

Antarctica: Measuring glacier velocity from satellite images

Many Landsat images of Antarctica show distinctive flow and crevasse features in the floating part of ice streams and outlet glaciers immediately below their grounding zones. Some of the features, which move with the glacier or ice stream, remain visible over many years and thus allow time-lapse measurements of ice velocities. Measurements taken from Landsat images of features on Byrd Glacier agree well with detailed ground and aerial observations. The satellite-image technique thus offers a rapid and cost-effective method of obtaining average velocities, to a first order of accuracy, of many ice streams and outlet glaciers near their termini.

Science↗
USGS2006

Rayleigh-wave diffractions due to a void in the layered half space

Void detection is challenging due to the complexity of near-surface materials and the limited resolution of geophysical methods. Although multichannel, high-frequency, surface-wave techniques can provide reliable shear (S)-wave velocities in different geological settings, they are not suitable for detecting voids directly based on anomalies of the S-wave velocity because of limitations on the resolution of S-wave velocity profiles inverted from surface-wave phase velocities. Xia et al. (2006a) derived a Rayleigh-wave diffraction traveltime equation due to a void in the homogeneous half space. Encouraging results of directly detecting a void from Rayleigh-wave diffractions were presented (Xia et al., 2006a). In this paper we used four two-dimensional square voids in the layered half space to demonstrate the feasibility of detecting a void with Rayleigh-wave diffractions. Rayleigh-wave diffractions were recognizable for all these models after removing direct surface waves by F-K filtering. We evaluate the feasibility of applying the Rayleigh-wave diffraction traveltime equation to a void in the layered earth model. The phase velocity of diffracted Rayleigh waves is predominately determined by surrounding materials of a void. The modeling results demonstrate that the Rayleigh-wave diffraction traveltime equation due to a void in the homogeneous half space can be applied to the case of a void in the layered half space. In practice, only two diffraction times are necessary to define the depth to the top of a void and the average velocity of diffracted Rayleigh waves. ?? 2005 Society of Exploration Geophysicists.

SEG Technical Program Expanded Abstracts↗
USGS2020

The effects of tissue fixation on sequencing and transcript abundance of nucleic acids from microdissected liver samples of smallmouth bass (Micropterus dolomieu)

There is an increasing emphasis on effects-based monitoring to document responses associated with exposure to complex mixtures of chemicals, climate change, pathogens, parasites and other environmental stressors in fish populations. For decades aquatic monitoring programs have included the collection of tissues preserved for microscopic pathology. Consequently, formalin-fixed, paraffin-embedded (FFPE) tissue can be an important reservoir of nucleic acids as technologies emerge that utilize molecular endpoints. Despite the cross-linking effects of formalin, its impact on nucleic acid quality and concentration, amplification, and sequencing are not well described. While fresh-frozen tissue is optimal for working with nucleic acids, FFPE samples have been shown to be conducive for molecular studies. Laser capture microdissection (LCM) is one technology which allows for collection of specific regions or cell populations from fresh or preserved specimens with pathological alterations, pathogens, or parasites. In this study, smallmouth bass (Micropterus dolomieu) liver was preserved in three different fixatives, including 10% neutral buffered formalin (NBF), Z-Fix® (ZF), and PAXgene® (PG) for four time periods (24 hr, 48 hr, seven days, and 14 days). Controls consisted of pieces of liver preserved in RNALater® or 95% ethanol. Smallmouth bass were chosen as they are an economically important sportfish and have been utilized as indicators of exposure to endocrine disruptors and other environmental stressors. Small liver sections were cut out with laser microdissection and DNA and RNA were purified and analyzed for nucleic acid concentration and quality. Sanger sequencing and the NanoString nCounter® technology were used to assess the suitability of these samples in downstream molecular techniques. The results revealed that of the formalin fixatives, NBF samples fixed for 24 and 48 hr were superior to ZF samples for both Sanger sequencing and the Nanostring nCounter®. The non-formalin PAXgene® samples were equally successful and they showed greater stability in nucleic acid quality and concentration over longer fixation times. This study demonstrated that small quantities of preserved tissue from smallmouth bass can be utilized in downstream molecular techniques; however, future studies will need to optimize the methods presented here for different tissue types, fish species, and pathological conditions.

PLoS ONE↗
USGS2025

The importance of method selection when estimating diet composition with quantitative fatty acid signature analysis

Quantitative fatty acid signature analysis (QFASA) is a common method of estimating the composition of prey species in the diets of consumers from polar and temperate ecosystems in which lipids are an important source of energy. A key characteristic of QFASA is that the large number of fatty acids that typically comprise lipids permits the dietary contributions of a correspondingly large number of prey types to be estimated. Several modifications to the original QFASA methods have been suggested in the literature and a significant extension of the original model published in 2017 allows simultaneous estimation of both diet proportions and calibration coefficients, which are metabolic constants in the model whose values must otherwise be estimated in independent feeding experiments. However, comparisons of diet estimates obtained using different estimation options have been limited. QFASA has been used to estimate the diet composition of several polar bear ( Ursus maritimus ) subpopulations, including the Southern Beaufort Sea (SBS) subpopulation. Prior QFASA estimates of SBS polar bear diet composition have most often been obtained using variations of the original QFASA model. We investigated the influence of variations in QFASA analytical methods on diet estimates by re-estimating the diet composition of polar bears from the Alaska portion of the SBS using three different methods and found that differences among the three sets of estimates were substantial. Our results illustrate how important the careful and deliberate selection of QFASA methods can be and we provide some guidance on techniques one might use to evaluate options.

PLoS ONE↗
USGS2017

Finite‐fault Bayesian inversion of teleseismic body waves

Inverting geophysical data has provided fundamental information about the behavior of earthquake rupture. However, inferring kinematic source model parameters for finite‐fault ruptures is an intrinsically underdetermined problem (the problem of nonuniqueness), because we are restricted to finite noisy observations. Although many studies use least‐squares techniques to make the finite‐fault problem tractable, these methods generally lack the ability to apply non‐Gaussian error analysis and the imposition of nonlinear constraints. However, the Bayesian approach can be employed to find a Gaussian or non‐Gaussian distribution of all probable model parameters, while utilizing nonlinear constraints. We present case studies to quantify the resolving power and associated uncertainties using only teleseismic body waves in a Bayesian framework to infer the slip history for a synthetic case and two earthquakes: the 2011 M w 7.1 Van, east Turkey, earthquake and the 2010 M w 7.2 El Mayor–Cucapah, Baja California, earthquake. In implementing the Bayesian method, we further present two distinct solutions to investigate the uncertainties by performing the inversion with and without velocity structure perturbations. We find that the posterior ensemble becomes broader when including velocity structure variability and introduces a spatial smearing of slip. Using the Bayesian framework solely on teleseismic body waves, we find rake is poorly constrained by the observations and rise time is poorly resolved when slip amplitude is low.

Bulletin of the Seismological Society of America↗
USGS1994

Analysis of larval trematode communities

We can compare natural communities with null models of communities to indicate how they differ from random assemblages of species (i.e., how much structure is present). However, because null models draw on observed values of species' prevalences, whatever structure already exists in natural communities affects the composition of a null model and weakens its comparative power. To address this, we developed formulae to estimate "pre—interactive" species prevalences permitting a more sensitive quantification of community structure. Nonetheless, if a null model deviates from the community that we base it on, it is difficult to separate the effects of heterogeneity in recruitment from competition. We have developed a method to test for each independently. Applying our analytical techniques to a well—studied guild of larval trematodes in the salt marsh snail Cerithidea californica revealed that competitive interactions among species were the most significant structuring force. Interestingly, spatial heterogeneity acted to significantly intensify species co—occurrences. This differs from previous studies, which argued that the isolating effects of spatial heterogeneity, not competition, structure these communities by reducing co—occurrences.

Ecology↗
USGS1963

Disease and infection in the Tetraonidae

Disease is one of many factors advanced to explain the fluctuations of grouse populations, but no profound study of natural disease losses in Tetraonidae exists. The literature contains frequent references to THE grouse disease, although many potential pathogens are listed in numerous surveys and limited investigations, and the relevant data indicate that no single etiologic agent is universally responsible for disease in grouse. Few experimental infections or related studies on parasite biology have been attempted. Well-trained personnel and specialized facilities are required for research and analysis (1) to develop new methods of interpretation to be used with existing census techniques, (2) to conduct intensive studies of ecological factors of host and habitat, and (3) to establish base lines for recognition of deviations from the norm. Disease in wildlife can be controlled only through management procedures based on information concerning the biology of pathogens, hosts, and environments. It cannot be studied as a separate entity if its impact on survival or population fluctuations of grouse is to be correctly assessed.

Journal of Wildlife Management↗
USGS1970

Age determination of raccoons

Age criteria, based on 61 skulls and eye lenses from 103 known-age captives, are described for separating raccoons ( Procyon lotor ) into eight age-classes as follows: young-of-the-year, 1, 2, 3, 4, 5, 6-7, > 7 years. Criteria studied were eye lens nitrogen, cranial suture closure, tooth wear and incisor cementum layers. Lens nitrogen increased rapidly up to 12 months of age, but at much reduced rate thereafter. Total lens nitrogen was useful only in separating young-of-the-year from adults. The closure sequence for five cranial sutures accurately divided the total known-age sample of males into seven groups, and the adults into five groups. The tooth wear criteria divided the known-age sample into five relative age groups, but aging of individuals by this method was inaccurate. Histological sectioning of known-age teeth was the best method of observing layering in the cementum tissue. The technique of basing estimation of age on cementum ring counts, although subjective, was accurate for aging individuals through their fourth year but tended to underestimate the age of animals over 4 years old. However, suture closure or tooth wear can be used to identify males over 4 years old. In field studies, technical difficulties limit the utility of age estimation by cementum layers. Maximum root thickness of the lower canine was accurate in determining the sex of individuals from 5 months to at least 48 months of age.

Illinois↗
USGS1971

The acoustic streamflow-measuring system on the Columbia River at The Dalles, Oregon

Records of discharge on the Columbia River at The Dalles, Oreg., are vital to the management of the complex water-development projects in the Columbia River basin. Accurate discharge figures are needed for consistent day-to-day management and are required to meet treaty obligations with Canada. Because dams have been erected that completely control watersurface elevations at nearly all points in the river from Bonneville Dam to the Canadian border, conventional stream-gaging methods, used historically, are no longer adequate. Consequently, new techniques must be used to obtain the accurate discharge records required--records that are computed independently from the hydroelectric operation logs and that stand alone as the recognized flow records in the basin. This need for an accurate, independent gaging system has been met by the installation of an acoustic streamflow-measuring system in the river channel at The Dalles, Oreg. This device provides an index of water velocity by measuring the difference in traveltimes of acoustic pulses transmitted through the water in each direction along a diagonal path across the river. The flow of water along the path increases the speed of one signal and retards the speed of the other. The difference in time of travel is related linearly to the water velocity along the path. The velocity index and river stage are used as a two-variable index in the computation of flow. These variables, correlated against current-meter measurements made with specialized boat equipment, provide a reliable basis for computations of instantaneous and daily mean discharges. Installation of this sytem, which is the first application of an AVM (acoustic velocity meter) in a large natural channel, was completed in April 1969. It has been in continuous operation since that date. Performance has been satisfactory, and similar installations at other key points in the Columbia River basin are now under consideration. This paper covers the general theory behind acoustic velocity meters, tracing development from earlier concepts to the present commercially available system. Conclusions are that the AVM can now be considered as an operational instrument which permits accurate gaging of river discharge at many sites where conventional stream-gaging procedures have proved to be unreliable.

Oregon↗
USGS2011

Inorganic chemical analysis of environmental materials—A lecture series

At the request of the faculty of the Colorado School of Mines, Golden, Colorado, the authors prepared and presented a lecture series to the students of a graduate level advanced instrumental analysis class. The slides and text presented in this report are a compilation and condensation of this series of lectures. The purpose of this report is to present the slides and notes and to emphasize the thought processes that should be used by a scientist submitting samples for analyses in order to procure analytical data to answer a research question. First and foremost, the analytical data generated can be no better than the samples submitted. The questions to be answered must first be well defined and the appropriate samples collected from the population that will answer the question. The proper methods of analysis, including proper sample preparation and digestion techniques, must then be applied. Care must be taken to achieve the required limits of detection of the critical analytes to yield detectable analyte concentration (above "action" levels) for the majority of the study's samples and to address what portion of those analytes answer the research question-total or partial concentrations. To guarantee a robust analytical result that answers the research question(s), a well-defined quality assurance and quality control (QA/QC) plan must be employed. This QA/QC plan must include the collection and analysis of field and laboratory blanks, sample duplicates, and matrix-matched standard reference materials (SRMs). The proper SRMs may include in-house materials and/or a selection of widely available commercial materials. A discussion of the preparation and applicability of in-house reference materials is also presented. Only when all these analytical issues are sufficiently addressed can the research questions be answered with known certainty.

Open-File Report↗
USGS1999

Spring-summer movements of bonytail in a Colorado River reservoir, Lake Mohave, Arizona and Nevada

The bonytail Gila elegans is a large-river minnow (Cyprinid) endemic to the Colorado River system of western North America. The species is federally listed as endangered, its biology poorly understood, and relatively little is known of its movements. Two short-term telemetry studies were conducted during 1996 and 1997 to assess spring-summer temporal and spatial movement patterns in Lake Mohave, Arizona and Nevada, where the largest remaining population of bonytail persists. A total of 20 bonytail were implanted with 90-day sonic transmitters. Ten fish (5 wild-caught from the Lake and 5 cove-reared: 5 females and 5 males) were implanted in May 1996 and additional 10 (7 wild-caught and 3 pond-reared: 2 females and 8 males) were implanted in April 1997, released into the lake immediately after surgery, and tracked approximately weekly through August of both years. Eight fish dispersed immediately after release in 1996, two moved up- and six moved down-lake. The five wild-caught fish moved down-lake as much as 42 km, and four of these (all males) remained in the lower most 5 km while the other (female) occupied an area about 10 km below the release site. Two cove fish moved up lake 15 and 43 km, respectively, while a third moved 4 km down-lake. Two fish were never contacted. Most locations were in shallow water along shorelines, in some instance within inundated stands of riparian vegetation. In 1997, three pond fish were surgically implanted with transmitters and released at Cottonwood Cove, Nevada. Two were not contacted again, and the other was lost 12 days post-release after moving approximately 1.4 km across the lake. Seven wild fish were captured and released at two sites in the lower portion of the lake, and all moved to downstream areas where they remained for the duration of study. Contact was lost with one fish after 3 days and another remained stationary after 13 days; the five others were tracked for 62 to 119 days. These last fish remained in the lower lake and had net movement (displacement from release site to last contact location) that averaged 5.4 km and ranged from 4.7 to 6.9 km. All net displacements were downstream. Cumulative distance traveled averaged 28.9 km and ranged from 19.9 to 33.0 km. Most fish locations during daylight hours were in deep water adjacent to the steep Nevada shore, while nighttime locations were in shallow water along gently sloping Arizona shorelines. Bonytail can move substantial distances in a short time (10s of km in a few days). Fish in both years apparently favored the same areas, where they may remain for weeks. Unmarked bonytail were observed or captured by setting nets in places favored by tagged fish, a significant result since future use of the technique may enhance our ability to monitor reintroductions, locate and document spawning, examine habitat use, and acquire desperately needed brood stock for this critically imperiled species. External tagging techniques developed for juvenile razorback sucker may provide a method of minimizing telemetry induced stress while allowing us to focus sampling on congregation sites.

Arizona, Nevada↗
USGS2010

Proceedings of the U.S. Geological Survey Interdisciplinary Microbiology Workshop, Estes Park, Colorado, October 15-17, 2008

Preface A U.S. Geological Survey Interdisciplinary Microbiology Workshop was held in Estes Park, Colorado, on October 15-17, 2008. Participants came from all USGS regions and disciplines. This report contains abstracts from 36 presentations and 35 poster sessions and notes from 5 breakout sessions. The seven presentation topics follow: Ecology of wildlife and fish disease Mechanisms of fish and wildlife disease Microbial ecology Geographic patterns/visualization Public health and water quality Geomicrobiology Ecosystem function The six poster session topics follow: Wildlife disease Disease detection methods Water quality Microbial ecology Metabolic processes Tools and techniques Five working groups met in breakout sessions on October 16, 2008. The highlights for each working group are summarized in this report, and their goals are listed below: Working Group I: to plan a Fact Sheet on interdisciplinary microbiology in the USGS Working Group II: to plan a USGS interdisciplinary microbiology Web site Working Group III: to suggest ways to broadcast and publicize the types of microbiology conducted at the USGS Working Group IV: to identify emerging issues in USGS interdisciplinary microbiology research Working Group V: to identify potential opportunities for interdisciplinary microbiology work at the USGS After the workshop, the USGS interdisciplinary microbiology Web site was activated in June 2009 at http://microbiology.usgs.gov/.

Scientific Investigations Report↗
USGS2024

Streamflow characterization and hydromodification, Indian and Kill Creek Basins, Johnson County, Kansas, 1985–2018

Urban stream restoration requires a quantitative understanding of hydromodification to provide a scientific basis for establishing, prioritizing, and monitoring stream quality improvement goals. A study by the U.S. Geological Survey, in cooperation with the Johnson County Urban stream restoration benefits from a quantitative understanding of hydromodification to provide a scientific basis for establishing, prioritizing, and monitoring stream quality improvement goals. A study by the U.S. Geological Survey, in cooperation with the Johnson County Stormwater Management Program, began in 2017 to assess streamflow conditions at U.S. Geological Survey streamgages along Indian and Kill Creeks in Johnson County, Kansas. These streams represent the most urban (Indian Creek) and least urban (Kill Creek) drainage basins in the county. The assessment used 40 streamflow indicators to characterize streamflow conditions for both streams and quantify the degree of hydromodification for Indian Creek. The 40 streamflow indicators consisted of 35 commonly used indicators for characterizing streamflow, 2 less common seasonality indicators, and 3 other indicators based on duration curves, runoff hydrographs, and streamflow percentile classes. The indicators represented five key components of the natural streamflow regime: magnitude, frequency, duration, timing, and rate of change. As part of the study, indicators were evaluated as to general utility for characterizing streamflow conditions, quantifying hydromodification, and assessing the effectiveness of implemented management practices intended to restore urban streams. Results identifying indicators that serve these purposes could be applied more generally to other streams in Johnson County to assess hydromodification and potential restoration opportunities. Although the same set of streamflow indicators may not apply to other regions, methods and results presented in this report provide guidance, techniques, and perspective for future related or similar studies elsewhere, particularly those designed to quantify hydromodification of urban streams and monitor the effectiveness of restoration efforts. Compared to Kill Creek, which, for the purposes of this study, was considered representative of a least disturbed rural reference condition, Indian Creek hydrology was determined to be substantially modified because of urbanization. Of the 35 streamflow indicators evaluated, 19 indicated a generally consistent and substantial difference between the 2 streams. Hydromodification of Indian Creek was characterized by larger annual mean and monthly mean streamflows (and, thus, larger streamflow volumes), larger low streamflows of shorter duration, larger high streamflows with increased frequency and shorter duration, faster rise and fall rates, and decreased seasonality of high and low streamflows. For the two seasonality indicators, seasonality of high and low streamflows decreased. Duration curves, runoff event hydrographs, and streamflow percentile classes also indicated differences between the two streams for specific ranges of streamflow. Indicators that were useful in identifying generally consistent and substantial differences between the two streams, and therefore demonstrating they collectively or individually may be indicators of hydromodification, included annual median and mean flows; monthly mean flows for February, July, August, September, October, November, and December; all the minimum mean flow indictors (1-day, 3-day, 7-day, 30-day, and 90-day); annual number and mean magnitude of peak flows; some of the flow pulse indicators; and rise and fall rates. Indicators determined to be marginally useful or not useful for identifying consistent and substantial streamflow differences between streams included the flashiness indicators Richards-Baker flashiness index and the fraction of the year the daily mean flow is greater than the annual mean flow, which was not expected. Municipalities are challenged by the need to restore stream quality in urbanized areas where options are limited because of existing development. Understanding hydromodification effects and implications for stream quality can help managers plan urban development that minimizes degradation of stream quality and provides insights for implementing effective management practices. Streamflow indicators identified in this report can be used to guide urban stream restoration. In particular, the most useful indicators could form the basis of numeric criteria for restoration goals aimed at achieving or progressing toward more natural streamflow conditions—and, by extension, more healthy ecosystems—by characterizing flow conditions, quantifying hydromodification, establishing stream-restoration goals, and monitoring progress toward achieving those goals as management practices are implemented.

Kansas↗
USGS1981

Flow routing in the Susquehanna River Basin: Part IV - Routing reservoir releases in the eastern Susqehanna river basin in New York State

Flow-routing models for six reaches of major streams in the eastern Susquehanna River basin in New York were developed and used to trace releases of water from East Sidney Lake and Whitney Point Lake to gaged points downstream. Daily streamflow during 1942-77 was modeled for the following reaches: Susquehanna River--Unadilla to Conklin, Conklin to Vestal, and Vestal to Waverly; Chenango River--Sherburne to Greene, and Greene to Chenango Forks; Tioughnioga River--Cortland to Itaska. The models were developed with convolution techniques and were based on the unit-response method of flow routing, assuming the diffusion analogy and using multilinearization. Overall accuracy of the models, as measured by the average difference between observed and simulated daily flows over the base period, was within the stated accuracy of published gaging-station records. As an example of one application of the models, hypothetical releases from East Sidney Lake and Whitney Point Lake during low flow were traced downstream to the Waverly gaging station at the lower end of the area studied. The leading edge of the East Sidney release arrived in 4 days, and the full release arrived in 6 days. The leading edge of the Whitney Point release arrived in 1 day, and the full release arrived in 3 days. (USGS)

Water-Resources Investigations Report↗
USGS1998

Guidelines for quality assurance and quality control of fish taxonomic data collected as part of the National Water-Quality Assessment Program

Fish community structure is characterized by the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program as part of a perennial, multidisciplinary approach to evaluating the physical, chemical, and biological conditions of the Nation's water resources. The objective of quality assurance and quality control of fish taxonomic data that are collected as part of the NAWQA Program is to establish uniform guidelines and protocols for the identification, processing, and archiving of fish specimens to ensure that accurate and reliable data are collected. Study unit biologists, collaborating with regional biologists and fish taxonomic specialists, prepare a pre-sampling study plan that includes a preliminary faunal list and identification of an ichthyological curation center for receiving preserved fish specimens. Problematic taxonomic issues and protected taxa also are identified in the study plan, and collecting permits are obtained in advance of sampling activities. Taxonomic specialists are selected to identify fish specimens in the field and to assist in determining what fish specimens should be sacrificed, fixed, and preserved for laboratory identification, independent taxonomic verification, and long-term storage in reference or voucher collections. Quantitative and qualitative sampling of fishes follows standard methods previously established for the NAWQA Program. Common ichthyological techniques are used to process samples in the field and prepare fish specimens to be returned to the laboratory or sent to an institutional repository. Taxonomic identifications are reported by using a standardized list of scientific names that provides nomenclatural consistency and uniformity across study units.

Water-Resources Investigations Report↗
USGS2014

Mapping mountain pine beetle mortality through growth trend analysis of time-series landsat data

Disturbances are key processes in the carbon cycle of forests and other ecosystems. In recent decades, mountain pine beetle (MPB; Dendroctonus ponderosae) outbreaks have become more frequent and extensive in western North America. Remote sensing has the ability to fill the data gaps of long-term infestation monitoring, but the elimination of observational noise and attributing changes quantitatively are two main challenges in its effective application. Here, we present a forest growth trend analysis method that integrates Landsat temporal trajectories and decision tree techniques to derive annual forest disturbance maps over an 11-year period. The temporal trajectory component successfully captures the disturbance events as represented by spectral segments, whereas decision tree modeling efficiently recognizes and attributes events based upon the characteristics of the segments. Validated against a point set sampled across a gradient of MPB mortality, 86.74% to 94.00% overall accuracy was achieved with small variability in accuracy among years. In contrast, the overall accuracies of single-date classifications ranged from 37.20% to 75.20% and only become comparable with our approach when the training sample size was increased at least four-fold. This demonstrates that the advantages of this time series work flow exist in its small training sample size requirement. The easily understandable, interpretable and modifiable characteristics of our approach suggest that it could be applicable to other ecoregions.

Colorado↗
USGS2009

Toward production from gas hydrates: Current status, assessment of resources, and simulation-based evaluation of technology and potential

Gas hydrates (GHs) are a vast energy resource with global distribution in the permafrost and in the oceans. Even if conservative estimates are considered and only a small fraction is recoverable, the sheer size of the resource is so large that it demands evaluation as a potential energy source. In this review paper, we discuss the distribution of natural GH accumulations, the status of the primary international research and development (R&D) programs, and the remaining science and technological challenges facing the commercialization of production. After a brief examination of GH accumulations that are well characterized and appear to be models for future development and gas production, we analyze the role of numerical simulation in the assessment of the hydrate-production potential, identify the data needs for reliable predictions, evaluate the status of knowledge with regard to these needs, discuss knowledge gaps and their impact, and reach the conclusion that the numerical-simulation capabilities are quite advanced and that the related gaps either are not significant or are being addressed. We review the current body of literature relevant to potential productivity from different types of GH deposits and determine that there are consistent indications of a large production potential at high rates across long periods from a wide variety of hydrate deposits. Finally, we identify (a) features, conditions, geology and techniques that are desirable in potential production targets; (b) methods to maximize production; and (c) some of the conditions and characteristics that render certain GH deposits undesirable for production. Copyright ?? 2009 Society of Petroleum Engineers.

Conference Paper↗
USGS1973

Aquifer diffusivity of the Ohio River alluvial aquifer by the flood-wave response method

Aquifer diffusivity (T/S) was calculated for 10 sites in the alluvial aquifer adjacent to the Ohio River by observing the response of the aquifer to a flood wave in the river. The calculated type curves matched the observed aquifer response reasonably well at eight of the 10 sites. The diffusivities ranged from 0.4 ft 2 sec -1 to 10.3 ft 2 sec -1 and were generally in agreement with diffusivity values calculated from pump-test methods at two of the sites. Interference from pumping 1/2 mile upstream from one site and localized aquifer inhomogeneity at another site precluded calculation of diffusivity. Determining the shape of the ground-water recession curve may be difficult, but it can be done satisfactorily by collecting water-level data during an extended period of ground-water discharge and transposing the average recession curve to the flood period being analyzed. The flood-wave response method for estimating aquifer diffusivity provides a relatively inexpensive technique for obtaining a significant part of the data needed to predict the aquifer's response to river and pumping stresses.

Ohio River↗