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At least 613 records · Page 34Linked to original sources
USGS2008

Scientific objectives of the Gulf of Mexico gas hydrate JIP leg II drilling

The Gulf of Mexico Methane Hydrate Joint Industry Project (JIP) has been performing research on marine gas hydrates since 2001 and is sponsored by both the JIP members and the U.S. Department of Energy. In 2005, the JIP drilled the Atwater Valley and Keathley Canyon exploration blocks in the Gulf of Mexico to acquire downhole logs and recover cores in silt- and clay-dominated sediments interpreted to contain gas hydrate based on analysis of existing 3-D seismic data prior to drilling. The new 2007-2009 phase of logging and coring, which is described in this paper, will concentrate on gas hydrate-bearing sands in the Alaminos Canyon, Green Canyon, and Walker Ridge protraction areas. Locations were selected to target higher permeability, coarser-grained lithologies (e.g., sands) that have the potential for hosting high saturations of gas hydrate and to assist the U.S. Minerals Management Service with its assessment of gas hydrate resources in the Gulf of Mexico. This paper discusses the scientific objectives for drilling during the upcoming campaign and presents the results from analyzing existing seismic and well log data as part of the site selection process. Alaminos Canyon 818 has the most complete data set of the selected blocks, with both seismic data and comprehensive downhole log data consistent with the occurrence of gas hydrate-bearing sands. Preliminary analyses suggest that the Frio sandstone just above the base of the gas hydrate stability zone may have up to 80% of the available sediment pore space occupied by gas hydrate. The proposed sites in the Green Canyon and Walker Ridge areas are also interpreted to have gas hydrate-bearing sands near the base of the gas hydrate stability zone, but the choice of specific drill sites is not yet complete. The Green Canyon site coincides with a 4-way closure within a Pleistocene sand unit in an area of strong gas flux just south of the Sigsbee Escarpment. The Walker Ridge site is characterized by a sand-prone sedimentary section that rises stratigraphically across the base of the gas hydrate stability zone and that has seismic indicators of gas hydrate.

Conference Paper↗
USGS2016

Geometric quality assessment of lidar data based on swath overlap

This paper provides guidelines on quantifying the relative horizontal and vertical errors observed between conjugate features in the overlapping regions of lidar data. The quantification of these errors is important because their presence quantifies the geometric quality of the data. A data set can be said to have good geometric quality if measurements of identical features, regardless of their position or orientation, yield identical results. Good geometric quality indicates that the data are produced using sensor models that are working as they are mathematically designed, and data acquisition processes are not introducing any unforeseen distortion in the data. High geometric quality also leads to high geolocation accuracy of the data when the data acquisition process includes coupling the sensor with geopositioning systems. Current specifications (e.g. Heidemann 2014) do not provide adequate means to quantitatively measure these errors, even though they are required to be reported. Current accuracy measurement and reporting practices followed in the industry and as recommended by data specification documents also potentially underestimate the inter-swath errors, including the presence of systematic errors in lidar data. Hence they pose a risk to the user in terms of data acceptance (i.e. a higher potential for Type II error indicating risk of accepting potentially unsuitable data). For example, if the overlap area is too small or if the sampled locations are close to the center of overlap, or if the errors are sampled in flat regions when there are residual pitch errors in the data, the resultant Root Mean Square Differences (RMSD) can still be small. To avoid this, the following are suggested to be used as criteria for defining the inter-swath quality of data: a) Median Discrepancy Angle b) Mean and RMSD of Horizontal Errors using DQM measured on sloping surfaces c) RMSD for sampled locations from flat areas (defined as areas with less than 5 degrees of slope) It is suggested that 4000-5000 points are uniformly sampled in the overlapping regions of the point cloud, and depending on the surface roughness, to measure the discrepancy between swaths. Care must be taken to sample only areas of single return points only. Point-to-Plane distance based data quality measures are determined for each sample point. These measurements are used to determine the above mentioned parameters. This paper details the measurements and analysis of measurements required to determine these metrics, i.e. Discrepancy Angle, Mean and RMSD of errors in flat regions and horizontal errors obtained using measurements extracted from sloping regions (slope greater than 10 degrees). The research is a result of an ad-hoc joint working group of the US Geological Survey and the American Society for Photogrammetry and Remote Sensing (ASPRS) Airborne Lidar Committee.

Conference Paper↗
USGS1969

Duck viral enteritis (duck plague) in North American Waterfowl

Duck Viral Enteritis (DVE) was first recognized in North America in January 1967, when an outbreak occurred in a commercial flock of white Pekin ducks in Suffolk County, Long Island, New York (Leibovitz and Hwang, 1968b). Originally described as a disease of domestic ducks in the Netherlands, DVE has since been reported from India and Belgium. it is also believed to have occurred in China and France (Jansen, 1968). This paper briefly reviews the status of DVE among wild waterfowl in North America and describes some of the characteristic lesions associated with this disease. The paper also mentions some of the work which has been undertaken to learn more about the status of DVE in North America.

Conference Paper↗
USGS1979

Organochlorine poisoning of herons

Over a period of years interested individuals have submitted many dead or moribund herons of various species to our laboratory to learn whether the birds had been affected by diseases or organochlorine poisoning. Residue concentrations in carcasses of birds and mammals are considered the best measure of sublethal exposure, whereas residues in brains are best to use for diagnosing death by most organochlorine chemicals (see Heinz et al. 1979 for review). Residue concentrations in brains that are diagnostic of organochlorine poisoning for birds have been determined in the laboratory for DDT and its metabolites (L.F. Stickel et al. 1966; W.H. Stickel et al. 1970; Stickel and Stickel 1970; W.H. Stickel, pers. comm.); dieldrin (W.H. Stickel et al. 1969; W.H. Stickel, pers. comm.); heptachlor, chlordane, and oxychlordane (L.F. Stickel et al. 1979; W.H. Stickel, pers. comm.); endrin (W.H. Stickel et al. 1979); Aroclor 1254 (W.H. Stickel 1975; W.H. Stickel, pers. comm.); and mirex (W.H. Stickel et al. 1973). This subject is discussed in further detail by Heinz et al. (1979). The purpose of the present paper is to document the occurrence and concentration of organochlorine residues in the brains of herons from various areas in the United States. By comparing these residue concentrations with laboratory-determined diagnostic lethal levels, we conclude that some herons were killed by organochlorine poisoning; others were at least seriously endangered by the residues they carried. Complete results of carcass analyses for these and other herons, as well as further details on residues in brains, will be reported elsewhere (H.M. Ohlendorf, D.M. Swineford, and L.N. Locke, unpublished manuscript). Overall, we analyzed carcasses or brains of more than 70 herons found dead or moribund and 36 others taken in planned collections. Residue levels in carcasses of many herons were not high enough to warrant analysis of brains. In the present paper we compare carcass and brain residues of dieldrin in 23 herons of which both carcass and brain were analyzed.

Alabama, Michigan, Vermont↗
USGS1988

Power formula for open-channel flow resistance

This paper evaluates various power formulas for flow resistance in open channels. Unlike the logarithmic resistance equation that can be theoretically derived either from Prandtl's mixing-length hypothesis or von Karman's similarity hypothesis, the power formula has long had an appearance of empiricism. Nevertheless, the simplicity in the form of the power formula has made it popular among the many possible forms of flow resistance formulas. This paper reexamines the concept and rationale of the power formulation, thereby addressing some critical issues in the modeling of flow resistance.

Conference Paper↗
USGS1988

Geologic characterization of seismic sources: Moving into the 1990s

The objective of this paper is to discuss leading-edge directions in paleoseismology and seismic geology, particularly as they relate to characterizing seismic sources. The paper builds on earlier articles that discuss some of these trends (Schwartz and Coppersmith, 1986; Schwartz, 1987). There are several areas that appear to be especially important. These are: fault segmentation, which provides a physical framework for evaluating both the size and potential location of future earthquakes on a fault zone; earthquake recurrence models, which provide information on the frequency of different size earthquakes on a fault; and long-term earthquake potential, an area in which significant advances have been made through development of earthquake hazard models that use probabilistic methodology to incorporate the uncertainties in seismic source characterization and the evolving understanding of the earthquake process.

Conference Paper↗
USGS1998

Integrating across scales: Effectively applying science for the successful conservation of Atlantic salmon (Salmo salar)

Atlantic salmon (Salmo salar) is an excellent species on which to focus synthetic, integrative investigations because it is an economically important species that captures the public imagination, is heavily impacted by humans, uses several ecosystems over its life, and is the subject of a large body of extant literature. The following 24 papers were solicited to provide the biological basis for effective and innovative approaches that biologists, managers, and social scientists can use to develop policies that sustain Atlantic salmon and related species. Together these papers highlight the need for and benefits of (a) synthesizing within populations, (b) choosing the appropriate scale, (c) comparing across populations using rigorous, focused, question-oriented methods, (d) integrating across disciplines, (e) incorporating the human perspective, (f) linking multiple ecosystems, and (g) applied problem solving. To show how Atlantic salmon can guide research and conservation efforts for other species in other systems, we review the justification for the supplement and summarize the defining concepts that emerge from the volume.

Conference Paper↗
USGS2004

Extracting transient Rayleigh wave and its application in detecting quality of highway roadbed

This paper first explains the tau-p mapping method of extracting Rayleigh waves (LR waves) from field shot gathers. It also explains a mathematical model of physical character parameters of quality of high-grade roads. This paper then discusses an algorithm of computing dispersion curves using adjacent channels. Shear velocity and physical character parameters are obtained by inversion of dispersion curves. The algorithm using adjacent channels to calculating dispersion curves eliminates average effects that exist by using multi-channels to obtain dispersion curves so that it improves longitudinal and transverse resolution of LR waves and precision of non-invasive detection, and also broadens its application fields. By analysis of modeling results of detached computation of the ground roll and real examples of detecting density and pressure strength of a high-grade roadbed, and by comparison of shallow seismic image method with borehole cores, we concluded that: 1 the abnormal scale and configuration obtained by LR waves are mostly the same as the result of shallow seismic image method; 2 an average relative error of density obtained from LR waves inversion is 1.6% comparing with borehole coring; 3 transient LR waves in detecting density and pressure strength of a high-grade roadbed is feasible and effective.

Conference Paper↗
USGS2004

Natural Attenuation Software (NAS): A computer program for estimating remediation times of contaminated groundwater

This paper describes the development and application of a modeling system called Natural Attenuation Software (NAS). NAS was designed as a screening tool to estimate times of remediation (TORs), associated with monitored natural attenuation (MNA), to lower groundwater contaminant concentrations to regulatory limits. Natural attenuation processes that NAS models include advection, dispersion, sorption, biodegradation, and non-aqueous phase liquid (NAPL) dissolution. This paper discusses the three main interactive components of NAS: 1) estimation of the target source concentration required for a plume extent to contract to regulatory limits, 2) estimation of the time required for NAFL contaminants in the source area to attenuate to a predetermined target source concentration, and 3) estimation of the time required for a plume extent to contract to regulatory limits after source reduction. The model's capability is illustrated by results from a case study at a MNA site, where NAS time of remediation estimates compared well with observed monitoring data over multiple years.

Conference Paper↗
USGS2007

Economic decision making and the application of nonparametric prediction models

Sustained increases in energy prices have focused attention on gas resources in low permeability shale or in coals that were previously considered economically marginal. Daily well deliverability is often relatively small, although the estimates of the total volumes of recoverable resources in these settings are large. Planning and development decisions for extraction of such resources must be area-wide because profitable extraction requires optimization of scale economies to minimize costs and reduce risk. For an individual firm the decision to enter such plays depends on reconnaissance level estimates of regional recoverable resources and on cost estimates to develop untested areas. This paper shows how simple nonparametric local regression models, used to predict technically recoverable resources at untested sites, can be combined with economic models to compute regional scale cost functions. The context of the worked example is the Devonian Antrim shale gas play, Michigan Basin. One finding relates to selection of the resource prediction model to be used with economic models. Models which can best predict aggregate volume over larger areas (many hundreds of sites) may lose granularity in the distribution of predicted volumes at individual sites. This loss of detail affects the representation of economic cost functions and may affect economic decisions. Second, because some analysts consider unconventional resources to be ubiquitous, the selection and order of specific drilling sites may, in practice, be determined by extraneous factors. The paper also shows that when these simple prediction models are used to strategically order drilling prospects, the gain in gas volume over volumes associated with simple random site selection amounts to 15 to 20 percent. It also discusses why the observed benefit of updating predictions from results of new drilling, as opposed to following static predictions, is somewhat smaller. Copyright 2007, Society of Petroleum Engineers.

Conference Paper↗
USGS2011

Survey of stranded gas and delivered costs to Europe of selected gas resources

Two important trends affecting the expected growth of global gas markets are (1) the shift by many industrialized countries from coal-fired electricity generation to the use of natural gas to generate electricity and (2) the industrialization of the heavily populated Asian countries of India and China. This paper surveys discovered gas in stranded conventional gas accumulations and presents estimates of the cost of developing and producing stranded gas in selected countries. Stranded gas is natural gas in discovered or identified fields that is not currently commercially producible for either physical or economic reasons. Published reserves of gas at the global level do not distinguish between volumes of gas in producing fields and volumes in nonproducing fields. Data on stranded gas reported here-that is the volumes, geographical distribution, and size distributions of stranded gas fields at the country and regional level-are based on the examination of individual-field data and represent a significant improvement in information available to industry and government decision makers. Globally, stranded gas is pervasive, but large volumes in large accumulations are concentrated in only a few areas. The cost component of the paper focuses on stranded conventional gas accumulations in Africa and South America that have the potential to augment supplies to Europe. The methods described for the computation of extraction and transport costs are innovative in that they use information on the sizes and geographical distribution of the identified stranded gas fields. The costs are based on industry data specific to the country and geologic basin where the stranded gas is located. Gas supplies to Europe can be increased significantly at competitive costs by the development of stranded gas. Net extraction costs of producing the identified gas depend critically on the natural-gas-liquids (NGLs) content, the prevailing prices of liquids, the size of the gas accumulation, and the deposit's location. The diversity of the distribution of stranded gas is one obstacle to the exercise of market power by the Gas Exporting Countries Forum (GECF).

Conference Paper↗
USGS2012

Development and application of downscaled hydroclimatic predictor variables for use in climate vulnerability and assessment studies

This paper outlines the production of 270-meter grid-scale maps for 14 climate and derivative hydrologic variables for a region that encompasses the State of California and all the streams that flow into it. The paper describes the Basin Characterization Model (BCM), a map-based, mechanistic model used to process the hydrological variables. Three historic and three future time periods of 30 years (1911–1940, 1941–1970, 1971–2000, 2010–2039, 2040–2069, and 2070–2099) were developed that summarize 180 years of monthly historic and future climate values. These comprise a standardized set of fine-scale climate data that were shared with 14 research groups, including the U.S. National Park Service and several University of California groups as part of this project. We present three analyses done with the outputs from the Basin Characterization Model: trends in hydrologic variables over baseline, the most recent 30-year period; a calibration and validation effort that uses measured discharge values from 139 streamgages and compares those to Basin Characterization Model-derived projections of discharge for the same basins; and an assessment of the trends of specific hydrological variables that links historical trend to projected future change under four future climate projections. Overall, increases in potential evapotranspiration dominate other influences in future hydrologic cycles. Increased potential evapotranspiration drives decreasing runoff even under forecasts with increased precipitation, and drives increased climatic water deficit, which may lead to conversion of dominant vegetation types across large parts of the study region as well as have implications for rain-fed agriculture. The potential evapotranspiration is driven by air temperatures, and the Basin Characterization Model permits it to be integrated with a water balance model that can be derived for landscapes and summarized by watershed. These results show the utility of using a process-based model with modules representing different hydrological pathways that can be inter-linked.

California↗
USGS2012

Integrated science and interdisciplinary research for parks and protected areas

This paper summarizes presentations and discussion that focused on integrated science and the use of interdisciplinary research during a panel session held at the George Wright Society Meeting in New Orleans, March 14, 2011. The panel brought together nationally recognized members from the social and biological scientific communities, along with decision-makers and managers of parks and protected areas. The goal of the panel was to spark a discussion among panel members and the audience on the benefits and challenges of utilizing interdisciplinary research and integrated science to answer complex questions at the international, national, regional, and local park levels. The key focus points for the panel presentations and subsequent discussion revolved around the following five questions: How do we define interdisciplinary research and integrated science? What are the benefits, drawbacks, and challenges of interdisciplinary research and integrated science? When should this type of science be used? What are the barriers to employing interdisciplinary research and integrated science, and how can those perceived barriers be overcome? What are some examples of situations where this type of science has worked for you? We will break this paper down into seven sections, each summarizing the results of the panel presentations and subsequent audience discussion: 1. How do we define integrated science and interdisciplinary research? 2. The need for integrated science. 3. The challenges of integrated science and interdisciplinary research. 4. The benefits of integrated science and interdisciplinary research. 5. Integrated science in protected area management. 6. Communicating integrated science. 7. Key components to improve scientific outcomes.

Conference Paper↗
USGS2010

A comparison between SWI and SEAWAT: the importance of dispersion, inversion and vertical anisotropy

SWI and SEAWAT are both computer codes designed to model variable-density systems. One of the options in SWI is to model Dupuit interface flow, where freshwater and seawater are separated by an interface. In this paper we compare seawater intrusion model results of SWI to model results of SEAWAT, which simulates full variable-density flow and transport. Results indicate that SWI is valid for many variable-density systems. For the case considered in this paper, SWI results are accurate when the simulated width of the transition zone between seawater to freshwater is 15% or less of the scale of the problem, density inversion (saltwater over freshwater) occurs over only a small part of the model domain, and the ratio of vertical to horizontal hydraulic conductivity is larger than 0.01. Results also show that the simulated interface moves further inland using SWI than for the same conditions using SEAWAT. SWI is preferable to be used in systems where run times for a fully-coupled variable-density flow and transport model would be prohibitive; for the case considered here, SWI run times were a few seconds and SEAWAT run times were almost three hours.

Conference Paper↗
USGS2014

Engineering uses of physics-based ground motion simulations

This paper summarizes validation methodologies focused on enabling ground motion simulations to be used with confidence in engineering applications such as seismic hazard analysis and dynmaic analysis of structural and geotechnical systems. Numberical simullation of ground motion from large erthquakes, utilizing physics-based models of earthquake rupture and wave propagation, is an area of active research in the earth science community. Refinement and validatoin of these models require collaboration between earthquake scientists and engineering users, and testing/rating methodolgies for simulated ground motions to be used with confidence in engineering applications. This paper provides an introduction to this field and an overview of current research activities being coordinated by the Souther California Earthquake Center (SCEC). These activities are related both to advancing the science and computational infrastructure needed to produce ground motion simulations, as well as to engineering validation procedures. Current research areas and anticipated future achievements are also discussed.

Conference Paper↗
USGS2015

Automated extraction of natural drainage density patterns for the conterminous United States through high performance computing

Hydrographic networks form an important data foundation for cartographic base mapping and for hydrologic analysis. Drainage density patterns for these networks can be derived to characterize local landscape, bedrock and climate conditions, and further inform hydrologic and geomorphological analysis by indicating areas where too few headwater channels have been extracted. But natural drainage density patterns are not consistently available in existing hydrographic data for the United States because compilation and capture criteria historically varied, along with climate, during the period of data collection over the various terrain types throughout the country. This paper demonstrates an automated workflow that is being tested in a high-performance computing environment by the U.S. Geological Survey (USGS) to map natural drainage density patterns at the 1:24,000-scale (24K) for the conterminous United States. Hydrographic network drainage patterns may be extracted from elevation data to guide corrections for existing hydrographic network data. The paper describes three stages in this workflow including data pre-processing, natural channel extraction, and generation of drainage density patterns from extracted channels. The workflow is concurrently implemented by executing procedures on multiple subbasin watersheds within the U.S. National Hydrography Dataset (NHD). Pre-processing defines parameters that are needed for the extraction process. Extraction proceeds in standard fashion: filling sinks, developing flow direction and weighted flow accumulation rasters. Drainage channels with assigned Strahler stream order are extracted within a subbasin and simplified. Drainage density patterns are then estimated with 100-meter resolution and subsequently smoothed with a low-pass filter. The extraction process is found to be of better quality in higher slope terrains. Concurrent processing through the high performance computing environment is shown to facilitate and refine the choice of drainage density extraction parameters and more readily improve extraction procedures than conventional processing.

Conference Paper↗
USGS2010

Data mining for water resource management part 2 - methods and approaches to solving contemporary problems

This is the second of two papers that describe how data mining can aid natural-resource managers with the difficult problem of controlling the interactions between hydrologic and man-made systems. Data mining is a new science that assists scientists in converting large databases into knowledge, and is uniquely able to leverage the large amounts of real-time, multivariate data now being collected for hydrologic systems. Part 1 gives a high-level overview of data mining, and describes several applications that have addressed major water resource issues in South Carolina. This Part 2 paper describes how various data mining methods are integrated to produce predictive models for controlling surface- and groundwater hydraulics and quality. The methods include: - signal processing to remove noise and decompose complex signals into simpler components; - time series clustering that optimally groups hundreds of signals into "classes" that behave similarly for data reduction and (or) divide-and-conquer problem solving; - classification which optimally matches new data to behavioral classes; - artificial neural networks which optimally fit multivariate data to create predictive models; - model response surface visualization that greatly aids in understanding data and physical processes; and, - decision support systems that integrate data, models, and graphics into a single package that is easy to use.

South Carolina↗
USGS1994

Pesticides detected in surface waters and fish of the Red River of the North drainage basin

The Red River of the North drainage basin (herein referred to as Red River Basin) within the United States is a study unit under the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) program. The overall goals of this program, initiated to better define the status and trends of the Nation’s water quality, are to address regional and national water-quality issues in a nationally consistent manner. Pesticide contamination of surface water and fish is one focus of this program. The Red River Basin is about 90,600 square kilometers (km2 ) in area and is composed of rolling prairie with a high density of prairie-pothole wetlands to the west; a very flat glacial lake bed with drainage ditches and meandering streams in the center (Red River Valley Lake Plain); morainal hills with a mosaic of agriculture, lakes, and forest in the southeast; and a flat lake-washed till plain with extensive peatlands in the northeast (fig. 1). Stoner and others (1993) have given a more complete description of the environmental setting of the Red River Basin. Agriculture is a major component of the region’s economy, and is greatest in the Red River Valley Lake Plain. Principal crops are wheat, barley, oats, sunflowers, corn, soybeans, dry beans, potatoes, sugarbeets, alfalfa hay, and other hay. Herbicide, insecticide, and fungicide use depends on crop type and environmental stresses such as crop disease, drought, and periodic insect-pest infestation. This paper focuses on the occurrence, movement, and fate of agricultural pesticides that are applied to crops, but improper disposal, and use of pesticides for household pests, lawn care, golf courses, and home gardening can also result in contamination of the aquatic environment. Furthermore, atmospheric transport is known to transport pesticides to regions far from their source (Kurtz, 1990). Pesticide data have been collected in the Red River Basin by various Federal, State, and local agencies. Tornes and Brigham (1994) recently summarized many of these historical data. This paper summarizes selected data collected as part of the NAWQA program during 1992-93, and briefly compares these data to historical data and to pesticide usage.

Minnesota, North Dakota, South Dakota↗