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At least 289 records · Page 16Linked to original sources
USGS1983

Statistical summary of daily values data and trend analysis of dissolved-solids data at National Stream Quality Accounting Network (NASQAN) stations

A statistical summary is provided of the available continuous and once-daily discharge, specific-conductance, dissolved oxygen , water temperature, and pH data collected at NASQAN stations during the 1973-81 water years and documents the period of record on which the statistical calculations were based. In addition, dissolved-solids data are examined by regression analyses to determine the relation between dissolved solids and specific conductance and to determine if long-term trends can be detected in dissolved-solids concentrations. Statistical summaries, regression equations expressing the relation between dissolved solids and specific conductance, and graphical presentations of trend analyses of dissolved solids are presented for 515 NASQAN stations in the United States, Canada, Guam, and Puerto Rico.

Water-Resources Investigations Report↗
USGS2018

Forecasting an invasive species’ distribution with global distribution data, local data, and physiological information

Understanding invasive species distributions and potential invasions often requires broad‐scale information on the environmental tolerances of the species. Further, resource managers are often faced with knowing these broad‐scale relationships as well as nuanced environmental factors related to their landscape that influence where an invasive species occurs and potentially could occur. Using invasive buffelgrass ( Cenchrus ciliaris ), we developed global models and local models for Saguaro National Park, Arizona, USA, based on location records and literature on physiological tolerances to environmental factors to investigate whether environmental relationships of a species at a global scale are also important at local scales. In addition to correlative models with five commonly used algorithms, we also developed a model using a priori user‐defined relationships between occurrence and environmental characteristics based on a literature review. All correlative models at both scales performed well based on statistical evaluations. The user‐defined curves closely matched those produced by the correlative models, indicating that the correlative models may be capturing mechanisms driving the distribution of buffelgrass. Given climate projections for the region, both global and local models indicate that conditions at Saguaro National Park may become more suitable for buffelgrass. Combining global and local data with correlative models and physiological information provided a holistic approach to forecasting invasive species distributions.

Arizona↗
USGS2020

Algorithm and data improvements for version 2.1 of the Climate Hazards center’s InfraRed Precipitation with Stations Data Set

To support global drought early warning, the Climate Hazards Center (CHC) at the University of California, Santa Barbara developed the Climate Hazards center InfraRed Precipitation with Stations (CHIRPS) dataset, in collaboration with the US Geological Survey and NASA SERVIR. Specifically designed to support early warning applications, CHIRPS has high a spatial resolution (0.05°), a long period of record (1981 to the near present), and relatively low latencies. Here we will describe a brief formal analysis of distributional bias in CHIRPS2.0. This analysis reveals, as expected, that CHIRPS2.0 means are very similar to observed station data. However, a closer look suggests that low precipitation values are underestimated and high values are over-estimated in the CHIRPS2.0. We describe a potential correction for this below.

Book chapter↗
USGS2006

Aeromagnetic and gravity data over the Central Transantarctic Mountains (CTAM), Antarctica: a website for the distribution of data and maps

Near complete coverage of the East Antarctic Shield by ice hampers geological study of crustal architecture important for understanding global tectonic and climate history. Limited exposures in the central Transantarctic Mountains (CTAM), however, show that Archean and Proterozoic rocks of the shield as well as Neoproterozoic-lower Paleozoic sedimentary successions were involved in oblique convergence associated with Gondwana amalgamation. Subsequently, the area was overprinted by Jurassic magmatism and Cenozoic uplift. To extend the known geology of the region to ice-covered areas, we conducted an aeromagnetic survey flown in draped mode by helicopters over the Central Transantarctic Mountains and by fixed-wing aircraft over the adjacent polar plateau. We flew more than 32,000 line km covering an area of nearly 60,000 km2 at an average altitude of 600 m, with average line spacing 2.5 km over most areas and 1.25 km over basement rocks exposed in the Miller and Geologists ranges. Additional lines flown to the north, south, and west extended preliminary coverage and tied with existing surveys. Gravity data was collected on the ground along a central transect of the helicopter survey area.

Open-File Report↗
USGS2010

Distribution of potential hydrothermally altered rocks in central Colorado derived from Landsat Thematic Mapper data: A geographic information system data set

As part of the Central Colorado Mineral Resource Assessment Project, the digital image data for four Landsat Thematic Mapper scenes covering central Colorado between Wyoming and New Mexico were acquired and band ratios were calculated after masking pixels dominated by vegetation, snow, and terrain shadows. Ratio values were visually enhanced by contrast stretching, revealing only those areas with strong responses (high ratio values). A color-ratio composite mosaic was prepared for the four scenes so that the distribution of potentially hydrothermally altered rocks could be visually evaluated. To provide a more useful input to a Geographic Information System-based mineral resource assessment, the information contained in the color-ratio composite raster image mosaic was converted to vector-based polygons after thresholding to isolate the strongest ratio responses and spatial filtering to reduce vector complexity and isolate the largest occurrences of potentially hydrothermally altered rocks.

Colorado↗
USGS1984

Methods for the collection of geochemical data from the sediments of the tidal Potomac River and estuary and data for 1978-1980

The chemical composition of bottom sediments and their associated pore waters from the tidal Potomac River and Estuary was studied from May 1978 through June 1980. Pore waters were routinely analyzed for pH, Eh, alkalinity, and concentrations of sulfide, sulfate, phosphate, carbon, ammonium, silica, iron, manganese, chloride, sodium, potassium, calcium, and magnesium. Porosity, weight loss on ignition, and carbon, nitrogen, and phosphorus contents were determined for the solid sediments. The range of salinity and chemical composition encountered in the estuary frequently necessitated modifications of standard methods of analysis. Therefore, the methods used, their modifications, and their limitations are presented in some detail. The appendix lists the data obtained from six sampling periods. (USGS)

Open-File Report↗
USGS2000

Methodology, data collection, and data analysis for determination of water-mixing patterns induced by aerators and mixers

The U.S. Geological Survey collected and analyzed data to describe mixing patterns induced by aerators and mixers to aid in the calibration and verification of a three-dimensional hydrodynamic model. During September 1995, three-dimensional water-velocity profiles were collected during the operation of fine-bubble and coarse-bubble aerators in a test tank at the U.S. Army Corps of Engineers Waterways Experiment Station. Three-dimensional water velocity, water-temperature, pH, dissolved oxygen concentration, and specific conductivity profiles were collected during operation of a coarse-bubble aerator in a reservoir in Schaumburg, Illinois, during summer 1996 and summer 1997, during strongly stratified and weakly stratified conditions. The effects of a submersible mixer alone and in combination with coarse-bubble aerators and a surface mixer alone also were investigated during summer 1997. The mixing patterns induced by the operation of aerators, submersible mixers, and surface mixers were described and compared with mixing patterns predicted by model simulations. Bubble-plume characteristics during tests in strongly stratified and weakly stratified conditions in the reservoir were documented and compared with characteristics simulated by different models. Lemckert and Imberger?s model simulates an entrainment rate similar to the rate measured during a test in the reservoir under strongly stratified conditions, whereas Schladow?s one-dimensional model appears to underestimate the total entrainment rate by about 50 percent. Schladow?s model was accurate during weak stratification but underestimated the radius of the plume during strong stratification. For 5 days during daylight hours, water temperature profiles were collected continuously during the operation of four aerators. Water temperatures in the reservoir were significantly affected by the operation of the aeration system. These changes were compared to simulations from a one-dimensional Dynamic Lake Model (DLM) simulation. DLM accurately simulated changes as a result of aeration, including daily changes. On the basis of temporal and spatial dissolved oxygen measurements, the volumetric quantity of oxygen in the reservoir was quantified before and after operation of a submersible mixer. A net loss of oxygen was calculated. This net loss may have resulted from a net warming of water throughout the reservoir or submerged supersaturated water releasing oxygen when the water came in contact with the atmosphere.

Water-Resources Investigations Report↗
USGS2002

Fecal-indicator bacteria in the Yakima River Basin, Washington: An examination of 1999 and 2000 synoptic-sampling data and their relation to historical data

The Yakima Basin National Water-Quality Assessment Program collected fecal-coliform bacteria samples during three synoptic samplings to identify and quantify the cause, source, transport, and effects of fecal-indicator bacteria in Yakima River Basin streams. The August 1999 synoptic sampling targeted the Yakima River main-stem and tributary sites, while the July and October-November 2000 synoptic samplings targeted small- and intermediate-sized agricultural watersheds during irrigation and nonirrigation season, respectively. Quality-assurance results indicated that variability in fecal-coliform concentrations is large and, therefore, a difference of an order of magnitude or more between sites or between times is required for the values to be significantly different 90 percent of the time. The August 1999 synoptic sampling results indicated that (1) 44 percent of the sites visited, including all the main-stem Yakima River sites, met the Class A fecal-coliform 90th percentile standard of 200 colonies per deciliter, (2) tributaries were the likely source of fecal contamination to the main stem, and (3) tributaries with high fecal-coliform concentrations typically also had high suspended-sediment concentrations. Results of the July and October-November 2000 synoptic samplings indicated that (1) 36 and 81 percent of the sites sampled, respectively, met the standard, (2) during the nonirrigation synoptic sampling, four of the six sites not meeting the standard were from the Granger and Sulphur subbasins, and (3) fecal-coliform concentrations during the irrigation season were generally higher than during the nonirrigation season. Several levels of temporal variability were examined. The short-term variability observed during a synoptic sampling was found to be site specific, with some sites fairly consistent, while others were rather variable. Seasonally, most sites from the 2000 synoptic samplings showed higher concentrations during irrigation than during nonirrigation. Historically, 13 of the 22 sites sampled during both the July 1988 and August 1999 synoptic samplings had higher concentrations in 1999. The three sites with the highest concentrations in July 1988, however, all had decreases in August 1999. When compared against historical (1972-85) minimum and maximum summer-month medians, the August 1999 synoptic-sampling concentrations generally were between these values. Instantaneous fecal-coliform bacteria loads were calculated for the August 1999 synoptic sampling in an effort to study the dynamics of bacterial transport. Tributaries affected by agricultural, urban, and hobby farm activities were generally the major sources of bacteria to the main-stem Yakima River during this time. When these August 1999 synoptic-sampling loads in the lower basin reach from the Yakima River at river mile 72 to Kiona (river mile 29.9) were compared to those from the July 1988 synoptic sampling, most sites had higher loads in 1999. A nonparametric Spearman test was used to detect correlations between fecal-coliform concentrations and physical and chemical data collected during the synoptic samplings. Results for the August 1999 synoptic sampling, which included many mouths of tributaries, showed strong significant correlations with almost every variable. In contrast, only some of the nutrient concentrations showed strong significant correlations during the July and October-November 2000 synoptic samplings, which included small and intermediate- sized agricultural streams. Looking forward relative to future monitoring goals, research needs, and best management practice development, four hypotheses that deal with processes and sources of bacteria were identified: (1) overland runoff transports bacteria from land surfaces to streams, (2) bacteria in the water column tend to associate with suspended matter, (3) with increasing densities of warm-blooded animals, the likelihood of fecal-coliform contamination in streams also increases, and (4) identifi- cation of bacterial sources is difficult, but must be attempted for remediation to be possible.

Washington↗
USGS1994

Refining 1970's Land-Use Data With 1990 Population Data to Indicate New Residential Development

A procedure using a geographic information system was developed to define urban land use representative of the 1990's by overlaying U.S. Bureau of the Census 1990 population density at the block group level on 1970's digital land-use data from 1:250,000-and 1: 100,000scale maps. Any area having a population density of 1,000 or more people per square mile is re-classified as "urban" land use in the derivative product. The procedure was applied to 20 study units of the National Water-Quality Assessment program to provide what are considered reasonable indications of urbanization that has occurred since the 1970's.

Water-Resources Investigations Report↗
USGS2015

Research data services in academic libraries: Data intensive roles for the future?

Objectives: The primary objectives of this study are to gauge the various levels of Research Data Service academic libraries provide based on demographic factors, gauging RDS growth since 2011, and what obstacles may prevent expansion or growth of services. Methods: Survey of academic institutions through stratified random sample of ACRL library directors across the U.S. and Canada. Frequencies and chi-square analysis were applied, with some responses grouped into broader categories for analysis. Results: Minimal to no change for what services were offered between survey years, and interviews with library directors were conducted to help explain this lack of change. Conclusion: Further analysis is forthcoming for a librarians study to help explain possible discrepancies in organizational objectives and librarian sentiments of RDS.

Journal of eScience Librarianship↗
USGS2021

Model structural uncertainty quantification and hydrogeophysical data integration using airborne electromagnetic data

A irborne electromagnetic (AEM) data are used to estimate large - scale model structural geometry, i.e. the spatial distribution of different lit hological units based on assumed or estimated resistivity - lithology relationships, and the uncertainty in those structures given imperfect measurements. Geophysically derived estimates of model structural uncertainty are then combined with hydrologic obse rvations to assess the impact of model structural error on hydrologic calibration and prediction errors. Using a synthetic numerical model, we describe a sequential hydrogeophysical approach that: (1) uses Bayesian Markov chain Monte Carlo (McMC) methods to produce a robust estimate of uncertainty in electrical resistivity parameter s , (2) combines geophysical parameter uncertainty estimates with borehole observations of lithology to produce probabilistic estimates of model structural uncertainty over the e ntire AEM survey area using geostatistical sequential indicator simulation algorithms, and (3) uses model structural estimates along with hydrologic observations to quantify both hydrologic parameter and prediction uncertainty using a second McMC sampling algorithm. Results of simulations will be presented that illustrate the complete workflow from geophysical parameter uncertainty analysis to the impact of model structural uncertainty on hydrologic parameter estimates.

Conference Paper↗
USGS2008

Radionuclide Data and Calculations and Loss-On-Ignition, X-Ray Fluorescence, and ICP-AES Data from Cores in Catchments of the Animas River, Colorado

The U.S. Departments of Agriculture and Interior Abandoned Mine Lands (AML) Initiative is focused on the evaluation of the effect of past mining practices on the water quality and the riparian and aquatic habitats of impacted stream reaches downstream from historical mining districts located primarily on Federal lands. This problem is manifest in the eleven western states (west of longitude 102 degrees) where the majority of hardrock mines that had past production are located on Federal lands. In areas of temperate climate and moderate to heavy precipitation, the effects of rapid chemical and physical weathering of sulfides exposed on mine-waste dumps and acidic drainage from mines have resulted in elevated metal concentrations in the stream water and stream-bed sediment. The result of these mineral weathering processes has an unquantified impact on the quality of the water and the aquatic and riparian habitats that may limit their recreational resource value. One of the confounding factors in these studies is the determination of the component of metals derived from hydrothermally altered but unmined portions of these drainage basins. Several watersheds have been studied to evaluate the effects of acid mine drainage and acid rock drainage on the near-surface environment. The Animas River watershed in southwestern Colorado contains a large number of past-producing metal mines that have affected the watershed. Beginning in October 1996, the U.S. Geological Survey (USGS) began a collaborative study of these effects under the USGS-AML Initiative. In this report, we present the radionuclide and geochemical analytical results of sediment coring during 1997-1999 from two cores from oxbow lakes 0.5 mi. upstream from the 32nd Street Bridge near Durango, Colo., and from three cores from beaver ponds within the Mineral Creek drainage basin near Silverton, Colo.

Data Series↗