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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 163 records · Page 9Linked to original sources
USGS2012

Inferring local competition intensity from patch size distributions: a test using biological soil crusts

Dryland vegetation is inherently patchy. This patchiness goes on to impact ecology, hydrology, and biogeochemistry. Recently, researchers have proposed that dryland vegetation patch sizes follow a power law which is due to local plant facilitation. It is unknown what patch size distribution prevails when competition predominates over facilitation, or if such a pattern could be used to detect competition. We investigated this question in an alternative vegetation type, mosses and lichens of biological soil crusts, which exhibit a smaller scale patch-interpatch configuration. This micro-vegetation is characterized by competition for space. We proposed that multiplicative effects of genetics, environment and competition should result in a log-normal patch size distribution. When testing the prevalence of log-normal versus power law patch size distributions, we found that the log-normal was the better distribution in 53% of cases and a reasonable fit in 83%. In contrast, the power law was better in 39% of cases, and in 8% of instances both distributions fit equally well. We further hypothesized that the log-normal distribution parameters would be predictably influenced by competition strength. There was qualitative agreement between one of the distribution's parameters (μ) and a novel intransitive (lacking a 'best' competitor) competition index, suggesting that as intransitivity increases, patch sizes decrease. The correlation of μ with other competition indicators based on spatial segregation of species (the C-score) depended on aridity. In less arid sites, μ was negatively correlated with the C-score (suggesting smaller patches under stronger competition), while positive correlations (suggesting larger patches under stronger competition) were observed at more arid sites. We propose that this is due to an increasing prevalence of competition transitivity as aridity increases. These findings broaden the emerging theory surrounding dryland patch size distributions and, with refinement, may help us infer cryptic ecological processes from easily observed spatial patterns in the field.

Oikos↗
USGS2010

Compilation of Water-Resources Data and Hydrogeologic Setting for the Allison Woods Research Station in Iredell County, North Carolina, 2005-2008

Water-resources data were collected to describe the hydrologic conditions at the Allison Woods research station near Statesville, North Carolina, in the Piedmont Physiographic Province of North Carolina. Data collected by the U.S. Geological Survey and the North Carolina Department of Environment and Natural Resources, Division of Water Quality, from April 2005 through September 2008 are presented in this report. Data presented include well-construction characteristics and periodic groundwater-level measurements for 29 wells, borehole geophysical logs for 8 wells, hourly groundwater-level measurements for 5 wells, continuous water-quality measurements for 3 wells, periodic water-quality samples for 12 wells and 1 surface-water station, slug-test results for 11 wells, and shallow groundwater-flow maps. In addition, the geology and hydrogeology at the site are summarized.

North Carolina↗
USGS1997

Land cover characterization and land surface parameterization research

The understanding of land surface processes and their parameterization in atmospheric, hydrologic, and ecosystem models has been a dominant research theme over the past decade. For example, many studies have demonstrated the key role of land cover characteristics as controlling factors in determining land surface processes, such as the exchange of water, energy, carbon, and trace gases between the land surface and the lower atmosphere. The requirements for multiresolution land cover characteristics data to support coupled-systems modeling have also been well documented, including the need for data on land cover type, land use, and many seasonally variable land cover characteristics, such as albedo, leaf area index, canopy conductance, surface roughness, and net primary productivity. Recently, the developers of land data have worked more closely with the land surface process modelers in these efforts.

Ecological Applications↗
USGS2007

Biogeochemistry of aquifer systems

Many studies have examined the differences in bacterial numbers, composition, and activity between groundwater and sediment samples. The majority of the literature has suggested higher percentages of attached bacteria than of unattached bacteria in aquifer systems, including in pristine aquifers and in aquifers contaminated with petroleum, creosote, sewage, and landfill leachate. In studies of aquifer biogeochemistry, much useful information regarding the microbial ecology of the system can be obtained by looking at organic compound and electron acceptor concentrations. An overview of approaches for identifying the redox characteristics of sediment is given in Christensen et al., and methods specific for determining reactive iron species in aquifers are reviewed by Heron et al. and Tuccillo et al. Other solid-phase electron acceptors that are important in aquifer systems include Mn(IV) oxides and barite. Important biogeochemical reactions catalyzed by indigenous microorganisms also are studied using a variety of experimental approaches including laboratory batch and column experiments as well as field-based in situ microcosms, tracer tests, and push-pull tests. The advantage of using a radiolabeled tracer in a study was that the reaction rates could be determined for the different steps in the denitrification pathway. Historically, researchers trained in geochemistry and hydrology created and tested hypotheses about aquifer biogeochemistry through laboratory assays and field-based geo-chemical measurements and experiments. Jeon et al. extended this research by using push-pull tests combined with stable-isotope probing to identify the specific members of the microbial community actively degrading naphthalene and rates of naphthalene degradation.

Book chapter↗
USGS2019

Integrating hydrology and biogeochemistry across frozen landscapes

Research has traditionally focused on atmospheric release of carbon from thawing permafrost, yet overlooked waterborne release pathways likely contribute significantly, especially in a warming Arctic. To address this knowledge gap and better constrain the fate of carbon in the North, we recommend inter-disciplinary efforts bridging physical, chemical and computational research.

Nature Communications↗
USGS1994

Crude-oil spill research project near Bemidji, Minnesota - Bibliography, 1984-1994

The U.S. Geological Survey began a research project at the site of a crude-oil spill near Bemidji, Minnesota in 1983. The project is part of the U.S. Geological Survey's Toxic Substances Hydrology Program. The objectives of research at the site are to obtain an understanding of the mobilization, transport, and fate of petroleum derivatives in the shallow subsurface and to use this understanding to develop predictive models of contaminant behavior. This report presents a bibliography of scientific papers that have been published from 1984 to early 1994. Research results have been published in scientific journals, conference proceedings, U.S. Geological Survey Reports, and academic theses.

Open-File Report↗
USGS2009

Integrated Science: Florida Manatees and Everglades Hydrology

Predicting and monitoring restoration effects on Florida manatees, which are known to make extended movements, will be incomplete if modeling and monitoring are limited to the smaller areas defined by the various res-toration components. U.S. Geological Survey (USGS) efforts, thus far, have focused on (1) collecting manatee movement data throughout the Ten Thousand Islands (TTI) region, and (2) developing an individual-based model for manatees to illustrate manatee responses to changes in hydrology related to the Picayune Strand Restoration Project (PSRP). In 2006, new regional research was begun to extend an Everglades hydrology model into the TTI region; extend the manatee movement model into the southern estuaries of Everglades National Park (ENP); and integrate hydrology and manatee data, models, and monitoring across the TTI region and ENP. Currently (2008), three research tasks are underway to develop the necessary modeling components to assess restoration efforts across the Greater Everglades Ecosystem.

Fact Sheet↗
USGS2024

Downstream decreases in water availability, tree height, canopy volume and growth rate in cottonwood forests along the Green River, southwestern USA

Hydrologic stress is increasing in Fremont cottonwood ( Populus fremontii ) forests across the southwestern United States because of increased temperature and streamflow diversion. The spatial variability of this stress is large yet poorly understood. Along the Yampa and Green Rivers in Colorado and Utah, vapour pressure deficit and flow diversions increase downstream. To investigate effects of this gradient on cottonwoods, we measured the percent live canopy and height of randomly selected trees at three sites: Deerlodge Park on the Yampa River (DLP), Island Park on the upper Green (ILP) and Canyonlands National Park on the lower Green (CAN). From these same trees, we took increment cores to understand differences in tree growth in each forest over time. We then related tree metrics to local water availability, streamflow and climatic data. Cottonwoods at CAN were shorter and had lower percent live canopy and growth rate than similarly aged trees upstream. CAN trees that grew higher above the water surface also tended to have lower tree growth, height and live canopy percentage. Furthermore, the correlation between tree growth and maximum vapour pressure deficit showed a much stronger negative shift since 1990 at CAN than at the other sites. All of these differences suggest higher hydrologic stress at CAN, which we attribute to the combined effects of peak flow declines from Flaming Gorge Reservoir, flow diversion and the higher and increasing vapour pressure deficit at CAN. Further research on the variability of hydrologic stress on cottonwoods could help managers anticipate and mitigate the effects of drought stress in these iconic forests.

Ecohydrology↗
USGS2008

A Study of the Connection Among Basin-Fill Aquifers, Carbonate-Rock Aquifers, and Surface-Water Resources in Southern Snake Valley, Nevada

The Secretary of the Interior through the Southern Nevada Public Lands Management Act approved funding for research to improve understanding of hydrologic systems that sustain numerous water-dependent ecosystems on Federal lands in Snake Valley, Nevada. Some of the streams and spring-discharge areas in and adjacent to Great Basin National Park have been identified as susceptible to ground-water withdrawals (Elliott and others, 2006) and research has shown a high potential for ground-water flow from southern Spring Valley into southern Snake Valley through carbonate rocks that outcrop along a low topographic divide known as the Limestone Hills (Welch and others, 2007). Comprehensive geologic, hydrologic, and chemical information will be collected and analyzed to assess the hydraulic connection between basin-fill aquifers and surface-water resources, water-dependent ecological features, and the regional carbonate-rock aquifer, the known source of many high-discharge springs. Understanding these connections is important because proposed projects to pump and export ground water from Spring and Snake Valleys in Nevada may result in unintended capture of water currently supplying springs, streams, wetlands, limestone caves, and other biologically sensitive areas (fig. 1). The methods that will be used in this study may be transferable to other areas in the Great Basin. The National Park Service, Bureau of Land Management, U.S. Fish and Wildlife Service, and U.S. Forest Service submitted the proposal for funding this research to facilitate science-based land management. Scientists from the U.S. Geological Survey (USGS) Water Resources and Geologic Disciplines, and the University of Nevada, Reno, will accomplish four research elements through comprehensive data collection and analysis that are concentrated in two distinct areas on the eastern and southern flanks of the Snake Range (fig. 2). The projected time line for this research is from July 2008 through September 2011.

Fact Sheet↗
USGS2008

Framework for Understanding Structural Errors (FUSE): A modular framework to diagnose differences between hydrological models

The problems of identifying the most appropriate model structure for a given problem and quantifying the uncertainty in model structure remain outstanding research challenges for the discipline of hydrology. Progress on these problems requires understanding of the nature of differences between models. This paper presents a methodology to diagnose differences in hydrological model structures: the Framework for Understanding Structural Errors (FUSE). FUSE was used to construct 79 unique model structures by combining components of 4 existing hydrological models. These new models were used to simulate streamflow in two of the basins used in the Model Parameter Estimation Experiment (MOPEX): the Guadalupe River (Texas) and the French Broad River (North Carolina). Results show that the new models produced simulations of streamflow that were at least as good as the simulations produced by the models that participated in the MOPEX experiment. Our initial application of the FUSE method for the Guadalupe River exposed relationships between model structure and model performance, suggesting that the choice of model structure is just as important as the choice of model parameters. However, further work is needed to evaluate model simulations using multiple criteria to diagnose the relative importance of model structural differences in various climate regimes and to assess the amount of independent information in each of the models. This work will be crucial to both identifying the most appropriate model structure for a given problem and quantifying the uncertainty in model structure. To facilitate research on these problems, the FORTRAN‐90 source code for FUSE is available upon request from the lead author.

Water Resources Research↗
USGS2003

The behavior of U- and Th-series nuclides in groundwater

Groundwater has long been an active area of research driven by its importance both as a societal resource and as a component in the global hydrological cycle. Key issues in groundwater research include inferring rates of transport of chemical constituents, determining the ages of groundwater, and tracing water masses using chemical fingerprints. While information on the trace elements pertinent to these topics can be obtained from aquifer tests using experimentally introduced tracers, and from laboratory experiments on aquifer materials, these studies are necessarily limited in time and space. Regional studies of aquifers can focus on greater scales and time periods, but must contend with greater complexities and variations. In this regard, the isotopic systematics of the naturally occurring radionuclides in the U- and Th- decay series have been invaluable in investigating aquifer behavior of U, Th, and Ra. These nuclides are present in all groundwaters and are each represented by several isotopes with very different half-lives, so that processes occurring over a range of time-scales can be studied (Table 1 ⇓ ). Within the host aquifer minerals, the radionuclides in each decay series are generally expected to be in secular equilibrium and so have equal activities (see Bourdon et al. 2003 ). In contrast, these nuclides exhibit strong relative fractionations within the surrounding groundwaters that reflect contrasting behavior during release into the water and during interaction with the surrounding host aquifer rocks. Radionuclide data can be used, within the framework of models of the processes involved, to obtain quantitative assessments of radionuclide release from aquifer rocks and groundwater migration rates. The isotopic variations that are generated also have the potential for providing fingerprints for groundwaters from specific aquifer environments, and have even been explored as a means for calculating groundwater ages.

Reviews in Mineralogy and Geochemistry↗
USGS2012

Book review: Earthquakes and water

It is really nice to see assembled in one place a discussion of the documented and hypothesized hydrologic effects of earthquakes. The book is divided into chapters focusing on particular hydrologic phenomena including liquefaction, mud volcanism, stream discharge increases, groundwater level, temperature and chemical changes, and geyser period changes. These hydrologic effects are inherently fascinating, and the large number of relevant publications in the past decade makes this summary a useful milepost. The book also covers hydrologic precursors and earthquake triggering by pore pressure. A natural need to limit the topics covered resulted in the omission of tsunamis and the vast literature on the role of fluids and pore pressure in frictional strength of faults. Regardless of whether research on earthquake-triggered hydrologic effects ultimately provides insight into the physics of earthquakes, the text provides welcome common ground for interdisciplinary collaborations between hydrologists and seismologists. Such collaborations continue to be crucial for investigating hypotheses about the role of fluids in earthquakes and slow slip. Review info: Earthquakes and Water. By Wang, C.-Y. and Manga, M., 2010. ISBN: 9783642008092, 218 pp.

Geofluids↗
USGS2006

Special issue: Terrestrial fluids, earthquakes and volcanoes: The Hiroshi Wakita volume I

Terrestrial Fluids, Earthquakes and Volcanoes: The Hiroshi Wakita Volume I is a special publication to honor Professor Hiroshi Wakita for his scientific contributions. This volume consists of 17 original papers dealing with various aspects of the role of terrestrial fluids in earthquake and volcanic processes, which reflect Prof. Wakita’s wide scope of research interests. Professor Wakita co-founded the Laboratory for Earthquake Chemistry in 1978 and served as its director from 1988 until his retirement from the university in 1997. He has made the laboratory a leading world center for studying earthquakes and volcanic activities by means of geochemical and hydrological methods. Together with his research team and a number of foreign guest researchers that he attracted, he has made many significant contributions in the above-mentioned scientific fields of interest. This achievement is a testimony to not only his scientific talent, but also his enthusiasm, his open mindedness, and his drive in obtaining both human and financial support.

Pure and Applied Geophysics↗
USGS2023

Automated mapping of culverts, bridges, and dams

Accurate maps of built structures around stream channels, such as dams, culverts, and bridges, are vital in monitoring infrastructure, risk management, and hydrologic modeling. Hydrologic modeling is essential for research and decisionmaking related to infrastructure and development planning, emergency management, ecology, and developing hydrographic data. Technological advances in remote sensing afford increasingly fine-scale elevation data, such as the U.S. Geological Survey 1-meter digital elevation models (DEMs), that can accurately model the Earth’s surface characteristics and related hydrologic dynamics. A long-standing challenge in flow modeling is the presence of built structures in an elevation model that resist flow in a way that does not reflect actual dynamics, such as culverts, bridges, and dams. This challenge is exacerbated in fine-scale elevation data as more built structures are resolved. Here we present a test of the extensibility of a culvert and dam detection workflow, culvert-net (CN). CN was developed using a large dataset of field-validated culverts, bridges, and dam locations for Alexander County, North Carolina, USA, supplemented by manual review and identification of additional features. In this workflow, the CN model is tested on a new study area in western Michigan, USA, where culverts and associated hydrography have recently been manually compiled.

Conference Paper↗
USGS2008

A reference data set of hillslope rainfall-runoff response, Panola Mountain Research Watershed, United States

Although many hillslope hydrologic investigations have been conducted in different climate, topographic, and geologic settings, subsurface stormflow remains a poorly characterized runoff process. Few, if any, of the existing data sets from these hillslope investigations are available for use by the scientific community for model development and validation or conceptualization of subsurface stormflow. We present a high-resolution spatial and temporal rainfall-runoff data set generated from the Panola Mountain Research Watershed trenched experimental hillslope. The data set includes surface and subsurface (bedrock surface) topographic information and time series of lateral subsurface flow at the trench, rainfall, and subsurface moisture content (distributed soil moisture content and groundwater levels) from January to June 2002. Copyright 2008 by the American Geophysical Union.

Water Resources Research↗
USGS2004

Synthesis of rainfall and runoff data used for Texas Department of Transportation Research Projects 0-4193 and 0-4194

In the early 2000s, the Texas Department of Transportation funded several research projects to examine the unit hydrograph and rainfall hyetograph techniques for hydrologic design in Texas for the estimation of design flows for stormwater drainage systems. A research consortium comprised of Lamar University, Texas Tech University, the University of Houston, and the U.S. Geological Survey (USGS), was chosen to examine the unit hydrograph and rainfall hyetograph techniques. Rainfall and runoff data collected by the USGS at 91 streamflow-gaging stations in Texas formed a basis for the research. These data were collected as part of USGS small-watershed projects and urban watershed studies that began in the late 1950s and continued through most of the 1970s; a few gages were in operation in the mid-1980s. Selected hydrologic events from these studies were available in the form of over 220 printed reports, which offered the best aggregation of hydrologic data for the research objectives. Digital versions of the data did not exist. Therefore, significant effort was undertaken by the consortium to manually enter the data into a digital database from the printed record. The rainfall and runoff data for over 1,650 storms were entered. To enhance data integrity, considerable quality-control and quality-assurance efforts were conducted as the database was assembled and after assembly to enhance data integrity. This report documents the database and informs interested parties on its usage.

Texas↗
USGS2026

Continental-scale prediction of hydrologic signatures and processes

Understanding how dominant hydrologic processes and their drivers vary across diverse continental-scale landscapes is critical for hydrologic modeling and water management applications. Our research addresses this question by synthesizing large-sample watershed datasets, Caravan and GAGES-II, and developing random forest models to identify patterns in hydrologic function. We assessed dominant processes by examining hydrologic signatures – summary indicators of watershed function derived from hydroclimatic time series and random forest models across 14 146 gauged United States watersheds. The results reveal clear continental-scale gradients in hydrologic processes, including baseflow, overland flow, storage, and water balance losses. Our map of dominant processes highlights, for example, the transition from baseflow to fast responses and back to baseflow along the elevation gradient from the Appalachian spine, through the Piedmont, to the Eastern Coastal Plain; a distinct outer ring around the Great Lakes region; and sharp contrasts between coastal and inland processes in the West. Variable importance analysis from random forest models show that processes in the western U.S. are primarily controlled by climate, whereas in the eastern U.S., soil, geology, and topography play larger roles, with distinct human influences apparent in urban areas. Our approach of estimating dominant processes and their drivers facilitates extending process knowledge from research watersheds to the continental scale, assessing current hydrological understanding, and evaluating hydrological model structures.

conterminous United States↗
USGS1994

Water-resources activities in New England, fiscal year 1993

The U.S. Geological Survey has 82 active or complete-except-report projects of hydrologic investigations ongoing within the New England Program Area. Of this total, 23 are data projects. Data projects contain statistics and data on the conditions of surface water, ground water, water quality and (or) water use for the study area. There currently are six data projects in Connecticut, five in Maine, four in Massachusetts, four in Rhode Island, and four in New Hampshire and Vermont. The remaining 59 of these projects are interpretive projects. Interpretive projects include research, aerial appraisal, and other hydrologic studies and include projects as diverse as (1) determining the direction of ground-water flow at a toxic site, (2) predicting the effect of acid rain on water quality of a reservoir, and (3) estimating yields of aquifers on Cape Cod. Of the interpretive projects, 26 are in Massachusetts, 17 in Connecticut, 17 are in New Hampshire and Vermont, 6 are in Maine, and 3 in Rhode Island. The report is compiled from project descriptions for fiscal year 1993. It briefly describes the water-resources activities and projects that were active in each District of the USGS, Water Resources Division, New England Program Area of September 30, 1993. Cooperator or funding source, problem statements, objectives, approaches, progress, and plans for next year are described for each project. The project area is located on a map of the appropriate State(s). The report contains a bibliography, by District and by author, of reports completed since 1977.

Open-File Report↗