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At least 883 records · Page 49Linked to original sources
USGS2008

Geologic map of Mount Mazama and Crater Lake Caldera, Oregon, including the database for the geologic map of Mount Mazama and Crater Lake Caldera, Oregon

Crater Lake partly fills one of the most spectacular calderas of the world, an 8-by-10-km basin more than 1 km deep formed by collapse of the volcano known as Mount Mazama (fig. 1) during a rapid series of explosive eruptions about 7,700 years ago. Having a maximum depth of 594 m, Crater Lake is the deepest lake in the United States. Crater Lake National Park, dedicated in 1902, encompasses 645 km2 of pristine forested and alpine terrain, including the lake itself, virtually all of Mount Mazama, and most of the area of the geologic map. The geology of the area was first described in detail by Diller and Patton (1902) and later by Williams (1942), whose vivid account led to international recognition of Crater Lake as the classic collapse caldera. Because of excellent preservation and access, Mount Mazama, Crater Lake caldera, and the deposits formed by the climactic eruption constitute a natural laboratory for study of volcanic and magmatic processes. For example, the climactic ejecta are renowned among volcanologists as evidence for systematic compositional zonation within a subterranean magma chamber. Mount Mazama's climactic eruption also is important as the source of the widespread Mazama ash, a useful Holocene stratigraphic marker throughout the Pacific Northwest, adjacent Canada, and offshore. A detailed bathymetric survey of the floor of Crater Lake in 2000 (Bacon and others, 2002) provides a unique record of postcaldera eruptions, the interplay between volcanism and filling of the lake, and sediment transport within this closed basin. Knowledge of the geology and eruptive history of the Mount Mazama edifice, greatly enhanced by the caldera wall exposures, gives exceptional insight into how large volcanoes of magmatic arcs grow and evolve. Lastly, the many smaller volcanoes of the High Cascades beyond the limits of Mount Mazama are a source of information on the flux of mantle-derived magma through the region. General principles of magmatic and eruptive processes revealed by the present study have been incorporated not only in scientific investigations elsewhere, but in the practical evaluation of hazards (Bacon and others, 1997b) and geothermal resources (Bacon and Nathenson, 1996) in the Crater Lake region. In addition to papers in scientific journals, field trip guides, and the hazard and geothermal reports, the major product of this long-term study of Mount Mazama is the geologic map. The map is unusual because it portrays bedrock (outcrop), surficial, and lake floor geology. Caldera wall geology is depicted in detail on the accompanying geologic panoramas.

Oregon↗
USGS2005

Augmenting two-dimensional hydrodynamic simulations with measured velocity data to identify flow paths as a function of depth on Upper St. Clair River in the Great Lakes basin

Upper St. Clair River, which receives outflow from Lake Huron, is characterized by flow velocities that exceed 7 feet per second and significant channel curvature that creates complex flow patterns downstream from the Blue Water Bridge in the Port Huron, Michigan, and Sarnia, Ontario, area. Discrepancies were detected between depth-averaged velocities previously simulated by a two-dimensional (2D) hydrodynamic model and surface velocities determined from drifting buoy deployments. A detailed ADCP (acoustic Doppler current profiler) survey was done on Upper St. Clair River during July 1–3, 2003, to help resolve these discrepancies. As part of this study, a refined finite-element mesh of the hydrodynamic model used to identify source areas to public water intakes was developed for Upper St. Clair River. In addition, a numerical procedure was used to account for radial accelerations, which cause secondary flow patterns near channel bends. The refined model was recalibrated to better reproduce local velocities measured in the ADCP survey. ADCP data also were used to help resolve the remaining discrepancies between simulated and measured velocities and to describe variations in velocity with depth. Velocity data from ADCP surveys have significant local variability, and statistical processing is needed to compute reliable point estimates. In this study, velocity innovations were computed for seven depth layers posited within the river as the differences between measured and simulated velocities. For each layer, the spatial correlation of velocity innovations was characterized by use of variogram analysis. Results were used with kriging to compute expected innovations within each layer at applicable model nodes. Expected innovations were added to simulated velocities to form integrated velocities, which were used with reverse particle tracking to identify the expected flow path near a sewage outfall as a function of flow depth. Expected particle paths generated by use of the integrated velocities showed that surface velocities in the upper layers tended to originate nearer the Canadian shoreline than velocities near the channel bottom in the lower layers. Therefore, flow paths to U.S. public water intakes located on the river bottom are more likely to be in the United States than withdrawals near the water surface. Integrated velocities in the upper layers are generally consistent with the surface velocities indicated by drifting-buoy deployments. Information in the 2D hydrodynamic model and the ADCP measurements was insufficient to describe the vertical flow component. This limitation resulted in the inability to account for vertical movements on expected flow paths through Upper St. Clair River. A three dimensional hydrodynamic model would be needed to account for these effects.

Scientific Investigations Report↗
USGS2014

Methods for estimating annual exceedance-probability discharges and largest recorded floods for unregulated streams in rural Missouri

Regression analysis techniques were used to develop a set of equations for rural ungaged stream sites for estimating discharges with 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probabilities, which are equivalent to annual flood-frequency recurrence intervals of 2, 5, 10, 25, 50, 100, 200, and 500 years, respectively. Basin and climatic characteristics were computed using geographic information software and digital geospatial data. A total of 35 characteristics were computed for use in preliminary statewide and regional regression analyses. Annual exceedance-probability discharge estimates were computed for 278 streamgages by using the expected moments algorithm to fit a log-Pearson Type III distribution to the logarithms of annual peak discharges for each streamgage using annual peak-discharge data from water year 1844 to 2012. Low-outlier and historic information were incorporated into the annual exceedance-probability analyses, and a generalized multiple Grubbs-Beck test was used to detect potentially influential low floods. Annual peak flows less than a minimum recordable discharge at a streamgage were incorporated into the at-site station analyses. An updated regional skew coefficient was determined for the State of Missouri using Bayesian weighted least-squares/generalized least squares regression analyses. At-site skew estimates for 108 long-term streamgages with 30 or more years of record and the 35 basin characteristics defined for this study were used to estimate the regional variability in skew. However, a constant generalized-skew value of -0.30 and a mean square error of 0.14 were determined in this study. Previous flood studies indicated that the distinct physical features of the three physiographic provinces have a pronounced effect on the magnitude of flood peaks. Trends in the magnitudes of the residuals from preliminary statewide regression analyses from previous studies confirmed that regional analyses in this study were similar and related to three primary physiographic provinces. The final regional regression analyses resulted in three sets of equations. For Regions 1 and 2, the basin characteristics of drainage area and basin shape factor were statistically significant. For Region 3, because of the small amount of data from streamgages, only drainage area was statistically significant. Average standard errors of prediction ranged from 28.7 to 38.4 percent for flood region 1, 24.1 to 43.5 percent for flood region 2, and 25.8 to 30.5 percent for region 3. The regional regression equations are only applicable to stream sites in Missouri with flows not significantly affected by regulation, channelization, backwater, diversion, or urbanization. Basins with about 5 percent or less impervious area were considered to be rural. Applicability of the equations are limited to the basin characteristic values that range from 0.11 to 8,212.38 square miles (mi 2 ) and basin shape from 2.25 to 26.59 for Region 1, 0.17 to 4,008.92 mi 2 and basin shape 2.04 to 26.89 for Region 2, and 2.12 to 2,177.58 mi 2 for Region 3. Annual peak data from streamgages were used to qualitatively assess the largest floods recorded at streamgages in Missouri since the 1915 water year. Based on existing streamgage data, the 1983 flood event was the largest flood event on record since 1915. The next five largest flood events, in descending order, took place in 1993, 1973, 2008, 1994 and 1915. Since 1915, five of six of the largest floods on record occurred from 1973 to 2012.

Missouri↗
USGS2017

Geologic field trip guide to Mount Mazama and Crater Lake Caldera, Oregon

Crater Lake partly fills one of the most spectacular calderas of the world—an 8 by 10 kilometer (km) basin more than 1 km deep formed by collapse of the Mount Mazama volcano during a rapid series of explosive eruptions ~7,700 years ago. Having a maximum depth of 594 meters (m), Crater Lake is the deepest lake in the United States. Crater Lake National Park, dedicated in 1902, encompasses 645 square kilometers (km 2 ) of pristine forested and alpine terrain, including the lake itself, and virtually all of Mount Mazama. The geology of the area was first described in detail by Diller and Patton (1902) and later by Williams (1942), whose vivid account led to international recognition of Crater Lake as the classic collapse caldera. Because of excellent preservation and access, Mount Mazama, Crater Lake caldera, and the deposits formed by the climactic eruption constitute a natural laboratory for study of volcanic and magmatic processes. For example, the climactic ejecta are renowned among volcanologists as evidence for systematic compositional zonation within a subterranean magma chamber. Mount Mazama’s climactic eruption also is important as the source of the widespread Mazama ash, a useful Holocene stratigraphic marker throughout the Pacific Northwest United States, adjacent Canada, and offshore. A detailed bathymetric survey of the floor of Crater Lake in 2000 (Bacon and others, 2002) provides a unique record of postcaldera eruptions, the interplay between volcanism and filling of the lake, and sediment transport within this closed basin. Knowledge of the geology and eruptive history of the Mount Mazama edifice, enhanced by the caldera wall exposures, gives exceptional insight into how large volcanoes of magmatic arcs grow and evolve. In addition, many smaller volcanoes of the High Cascades beyond the limits of Mount Mazama provide information on the flux of mantle-derived magma through the region. General principles of magmatic and eruptive processes revealed by geologic research at Crater Lake have been incorporated not only in scientific investigations elsewhere, but also in the practical evaluation of local hazards (Bacon and others, 1997b) and geothermal resources (Bacon and Nathenson, 1996). The 1:24,000-scale geologic map of Mount Mazama and Crater Lake caldera (Bacon, 2008) is unusual because it portrays bedrock (outcrop), surficial, and lake floor geology. Caldera wall geology is depicted in detail on the accompanying geologic panoramas, and bedrock geology is shown in a 1:50,000-scale geologic map. This field guide supersedes earlier geology guides of Crater Lake (Bacon, 1987, 1989).

Oregon↗
USGS1982

Preliminary evaluation of the ground-water-flow system in the Twin Cities Metropolitan area, Minnesota

A preliminary quasi-three-dimensional finite-difference ground-water-flow model of the seven-county Twin Cities Metropolitan area was constructed and used to evaluate parameter sensitivity and adequacy of available data. Fourteen geologic units that underlie the study area were grouped into nine hydr,bgeologic units and were incorporated into a five-layer model. The layers in the simulation model include the Mount SimonHinckley, Ironton-Galesville, Prairie du Chien-Jordan, and St. Peter aquifers, and the drift. Sensitivity analyses were made for 19 parameter and boundary-condition specifications. Model results are -most sensitive to recharge and withdrawal rates and to hydrogeologic variations related to drift-filled bedrock valleys. Analyses of available data and results of steady-state simulations indicate that critical data needs for improving the simulation model include spatial and temporal variations in ground-water withdrawals and potentiometric levels, and hydraulic properties of drift filling or partly filling bedrock valleys. Areal distribution of calcium, sodium, sulfate, and chloride concentrations were analyzed to provide information on the hydrologic and geochemical relationships between aquifers. Ground water is generally of the calcium magnesium bicarbonate type. Concentration of dissolved solids in water from the Jordan Sandstone and Mount Simon-Hinckley aquifer generally decreases from southwest to northeast across the study area. This decrease probably reflects differences in the quality of recharge water and geochemical processes within the aquifers, such as ion exchange.

Minnesota↗
USGS2013

Improving predictive power of physically based rainfall-induced shallow landslide models: a probablistic approach

Distributed models to forecast the spatial and temporal occurrence of rainfall-induced shallow landslides are deterministic. These models extend spatially the static stability models adopted in geotechnical engineering and adopt an infinite-slope geometry to balance the resisting and the driving forces acting on the sliding mass. An infiltration model is used to determine how rainfall changes pore-water conditions, modulating the local stability/instability conditions. A problem with the existing models is the difficulty in obtaining accurate values for the several variables that describe the material properties of the slopes. The problem is particularly severe when the models are applied over large areas, for which sufficient information on the geotechnical and hydrological conditions of the slopes is not generally available. To help solve the problem, we propose a probabilistic Monte Carlo approach to the distributed modeling of shallow rainfall-induced landslides. For the purpose, we have modified the Transient Rainfall Infiltration and Grid-Based Regional Slope-Stability Analysis (TRIGRS) code. The new code (TRIGRS-P) adopts a stochastic approach to compute, on a cell-by-cell basis, transient pore-pressure changes and related changes in the factor of safety due to rainfall infiltration. Infiltration is modeled using analytical solutions of partial differential equations describing one-dimensional vertical flow in isotropic, homogeneous materials. Both saturated and unsaturated soil conditions can be considered. TRIGRS-P copes with the natural variability inherent to the mechanical and hydrological properties of the slope materials by allowing values of the TRIGRS model input parameters to be sampled randomly from a given probability distribution. The range of variation and the mean value of the parameters can be determined by the usual methods used for preparing the TRIGRS input parameters. The outputs of several model runs obtained varying the input parameters are analyzed statistically, and compared to the original (deterministic) model output. The comparison suggests an improvement of the predictive power of the model of about 10% and 16% in two small test areas, i.e. the Frontignano (Italy) and the Mukilteo (USA) areas, respectively. We discuss the computational requirements of TRIGRS-P to determine the potential use of the numerical model to forecast the spatial and temporal occurrence of rainfall-induced shallow landslides in very large areas, extending for several hundreds or thousands of square kilometers. Parallel execution of the code using a simple process distribution and the Message Passing Interface (MPI) on multi-processor machines was successful, opening the possibly of testing the use of TRIGRS-P for the operational forecasting of rainfall-induced shallow landslides over large regions.

Geoscientific Model Development and Discussions↗
USGS1986

Applications of Landsat data and the data base approach

A generalized methodology for applying digital Landsat data to resource inventory and assessment tasks is currently being used by several bureaux and agencies within the US Department of the Interior. The methodology includes definition of project objectives and output, identification of source materials, construction of the digital data base, performance of computer-assisted analyses, and generation of output. The USGS, Bureau of Land Management, US Fish and Wildlife Service, Bureau of Indian Affairs, Bureau of Reclamation, and National Park Service have used this generalized methodology to assemble comprehensive digital data bases for resource management. Advanced information processing techniques have been applied to these data bases for making regional environmental surveys on millions of acres of public lands at costs ranging from $0.01 to $0.08 an acre.-Author

Photogrammetric Engineering and Remote Sensing↗
USGS2016

Factors affecting wetland connectivity for wintering semipalmated sandpipers ( Calidris pusilla ) in the Caribbean

Wetland connectivity provides migratory shorebirds varying options to meet energy requirements to survive and complete their annual cycle. Multiple factors mediate movement and residency of spatially segregated wetlands. Information on these factors is lacking in the tropics, yet such information is invaluable for conservation design. The influence of seven biotic and abiotic factors on local movement and residency rates of Semipalmated Sandpipers ( Calidris pusilla ) among three major wetlands in southwestern Puerto Rico in 2013–2014 was assessed using multi-state models. The model with highest support (AIC c w i = 0.78) indicated that weekly residency rates increased seasonally, and were positively influenced by bird abundance and the interaction of prey density and rainfall. Movement rates were negatively influenced by inter-wetland distance, which varied annually, ranging from 0.01 ± 0.004 to 0.33 ± 0.08. Age class (adult, juvenile), extent of shoreline habitat (km), and body condition (estimated percent fat) did not influence residency rates (95% CIs overlapped Betas). Our findings indicated that coastal wetlands in southwestern Puerto Rico were connected, pointing at the joint value of salt flats and mangroves for overwintering Semipalmated Sandpipers. Connectivity between different types of wetlands likely widens resource diversity, which is essential for coping with unpredictable environments. Additional work is needed to generalize our understanding of inter-wetland dynamics and their potential benefits to inform shorebird conservation strategies in the Caribbean.

Puerto Rico↗
USGS2020

Mineralogy and lithology of the Upper Cretaceous Niobrara Formation determined by hyperspectral core imaging

Sections of the Upper Cretaceous (Coniacian to Campanian) Niobrara Formation in two cores from Kansas and Colorado, the Amoco Rebecca Bounds and USGS Portland 1, respectively, were examined by hyperspectral core imaging and analysis. A spectral imaging system combining high-resolution photography (50 μm), 3D laser profiling (20 μm), and near-visible + short-wave infrared reflectance spectroscopy (wavelengths from 450 to 2500 nm, 500 μm pixel size) was applied to these cores to provide spectral and textural data facilitating creation of continuous mineral and lithology class maps. In addition, compositing of pixel-based results to group pixels to create mineralogical and lithological logs (0.5 ft resolution) was performed to facilitate comparisons to other geochemical datasets. The results show general correspondence in trends identified by previous geochemistry studies, with some exceptions due to instrumental limitations related to low reflectance of some rock intervals and the limited range of infrared wavelengths examined. This study provides a cursory overview of an extensive dataset meant to demonstrate the utility of hyperspectral core scanning to studies of mudrocks in petroleum systems as well as the kinds of information this technique can provide for detailed examination of stratigraphic features in sedimentary systems more generally.

Mountain Geologist↗
USGS2020

Flood-frequency estimation for very low annual exceedance probabilities using historical, paleoflood, and regional information with consideration of nonstationarity

Streamflow estimates for floods with an annual exceedance probability of 0.001 or lower are needed to accurately portray risks to critical infrastructure, such as nuclear powerplants and large dams. However, extrapolating flood-frequency curves developed from at-site systematic streamflow records to very low annual exceedance probabilities (less than 0.001) results in large uncertainties in the streamflow estimates. Traditionally, methods for statistically estimating flood frequency have relied on the systematic streamflow record, which provides a time series of annual maximum flood peaks, often including some historical peaks. However, most peak-flow records are less than 100 years, and uncertainties are large when trying to extrapolate magnitudes of very low annual exceedance probability events. Other data may be available that extend the record beyond the systematic dataset. Historical data are defined as data from outside the period of systematic records but within the period of human records. Examples of historical information include flood estimates from other agencies and newspaper accounts that can be translated to flood magnitude point estimates, interval estimates, or perception thresholds (such as a statement that an 1880 flood was the largest since 1869). Paleoflood data, which may also extend the dataset, include a broad range of information about flood occurrence or magnitude from sources like sediment deposits or tree rings. Several assumptions are made in flood-frequency analysis, and an understanding of whether the data conform to these assumptions is desired. A particularly difficult assumption to evaluate for flood-frequency analysis is the underlying assumption that the flood series is stationary—the assumption that a time series of peak flow varies around a constant mean within a particular range of values (constant variance). As the hydrologic community’s understanding of natural systems and anthropogenic effects on streamflows has evolved, the community has come to understand that many surface-water systems exhibit one or more forms of nonstationarity, and thus the stationarity assumption is often violated to some degree. However, there is currently (2020) no consensus among hydrologists regarding the most appropriate flood-frequency-analysis methods for nonstationary systems, and this topic remains an active area of research. A literature review was completed to summarize the state of the science of flood frequency. The literature review highlights tools available to detect nonstationarities and identifies approaches that include external information to inform flood-frequency analysis. To demonstrate methods for initial data analysis and for incorporating historical and paleoflood information in flood-frequency analysis, five sites were selected: the Red River of the North at James Avenue Pumping Station, Winnipeg, Manitoba, Canada; lower reach, Rapid Creek, South Dakota; Spring Creek, South Dakota; Cherry Creek near Melvin, Colorado; and Escalante River near Escalante, Utah. The sites were chosen for the availability of published historical and paleoflood data and for their geographic diversity and unique characteristics, which highlighted issues such as autocorrelation, change points, trends, outlier peaks, or short periods of record. An initial data analysis that involved examining records for autocorrelation, change points, and trends was completed for all sites. The flood-frequency analysis completed for this study used version 7.2 of the U.S. Geological Survey PeakFQ program. Multiple analyses were done on each site documenting the change in the flood-frequency curve when additional historical or paleoflood data were added. When other flood-frequency studies were available, their results were compared to the results here. The comparisons in some cases simply show the effect of additional years of data, whereas other comparisons show results from probability distributions or fitting methods other than those used in PeakFQ. For the Red River of the North, flood-frequency analysis shows that paleoflood data appear necessary to reasonably estimate very low annual exceedance probabilities. For the analysis of the lower reach of Rapid Creek and Spring Creek, paleoflood information helped put a high outlier from the systematic period in context; however, very low annual exceedance probabilities at these sites still had extraordinarily large confidence bounds. These sites also showed that paleoflood information might be transferred from one site to another, with the caveat that this is a case where we had existing paleoflood data to test the transfer of paleoflood information—this is not the case at many sites, and transferring paleoflood information requires assumptions about the comparability of floods at the sites. The Cherry Creek analysis affirmed the result of an earlier study that showed that the generalized Pareto distribution was not a good distribution for estimating very low annual exceedance probabilities. The Escalante River analysis showed that adding paleoflood information might increase uncertainty for very low annual exceedance probabilities, compared to analysis with the systematic period of record information only, when the paleoflood peaks are of much larger magnitudes than the systematic record.

Scientific Investigations Report↗
USGS2013

Overview of groundwater quality in the Piceance Basin, western Colorado, 1946--2009

Groundwater-quality data from public and private sources for the period 1946 to 2009 were compiled and put into a common data repository for the Piceance Basin. The data repository is available on the web at http://rmgsc.cr.usgs.gov/cwqdr/Piceance/index.shtml. A subset of groundwater-quality data from the repository was compiled, reviewed, and checked for quality assurance for this report. The resulting dataset consists of the most recently collected sample from 1,545 wells, 1,007 (65 percent) of which were domestic wells. From those samples, the following constituents were selected for presentation in this report: dissolved oxygen, dissolved solids, pH, major ions (chloride, sulfate, fluoride), trace elements (arsenic, barium, iron, manganese, selenium), nitrate, benzene, toluene, ethylbenzene, xylene, methane, and the stable isotopic compositions of water and methane. Some portion of recharge to most of the wells for which data were available was derived from precipitation (most likely snowmelt), as indicated by δ2H [H2O] and δ18O[H2O] values that plot along the Global Meteoric Water Line and near the values for snow samples collected in the study area. Ninety-three percent of the samples were oxic, on the basis of concentrations of dissolved oxygen that were greater than or equal to 0.5 milligrams per liter. Concentration data were compared with primary and secondary drinking-water standards established by the U.S. Environmental Protection Agency. Constituents that exceeded the primary standards were arsenic (13 percent), selenium (9.2 percent), fluoride (8.4 percent), barium (4.1 percent), nitrate (1.6 percent), and benzene (0.6 percent). Concentrations of toluene, xylenes, and ethylbenzene did not exceed standards in any samples. Constituents that exceeded the secondary standard were dissolved solids (72 percent), sulfate (37 percent), manganese (21 percent), iron (16 percent), and chloride (10 percent). Drinking-water standards have not been established for methane, which was detected in 24 percent of samples. Methane concentrations were greater than or equal to 1 milligram per liter in 8.5 percent of samples. Methane isotopic data for samples collected primarily from domestic wells in Garfield County indicate that methane in samples with relative high methane concentrations were derived from both biogenic and thermogenic sources. Many of the constituents that exceeded standards, such as arsenic, fluoride, iron, and manganese, were derived from rock and sediment in aquifers. Elevated nitrate concentrations were most likely derived from human sources such as fertilizer and human or animal waste. Information about the geologic unit or aquifer in which a well was completed generally was not provided by data sources. However, limited data indicate that Quaternary deposits in Garfield and Mesa Counties, the Wasatch Formation in Garfield County, and the Green River Formation in Rio Blanco County had some of the highest median concentrations of selected constituents. Variations in concentration with depth could not be evaluated because of the general lack of well-depth and water-level data. Concentrations of several important constituents, such as arsenic, manganese, methane, and nitrate, were related to concentrations of dissolved oxygen. Concentrations of arsenic, manganese, and methane were significantly higher in groundwater with low dissolved-oxygen concentrations than in groundwater with high dissolved-oxygen concentrations. In contrast, concentrations of nitrate were significantly higher in groundwater with high dissolved-oxygen concentrations than in groundwater with low dissolved-oxygen concentrations. These results indicate that measurements of dissolved oxygen may be a useful indicator of groundwater vulnerability to some human-derived contaminants and enrichment from some natural constituents. Assessing such a large and diverse dataset as the one available through the repository poses unique challenges for reporting on groundwater quality in the study area. The repository contains data from several studies that differed widely in purpose and scope. In addition to this variability in available data, gaps exist spatially, temporally, and analytically in the repository. For example, groundwater-quality data in the repository were not evenly distributed throughout the study area. Several key water-quality constituents or indicators, such as dissolved oxygen, were underrepresented in the repository. Ancillary information, such as well depth, depth to water, and the geologic unit or aquifer in which a well was completed, was missing for more than 50 percent of samples. Future monitoring could avoid several limitations of the repository by making relatively minor changes to sample- collection and data-reporting protocols. Field measurements for dissolved oxygen could be added to sampling protocols, for example. Information on well construction and the geologic unit or aquifer in which a well was completed should be part of the water-quality dataset. Such changes would increase the comparability of data from different monitoring programs and also add value to each program individually and to that of the regional dataset as a whole. Other changes to monitoring programs could require greater resources, such as sampling for a basic set of constituents that is relevant to major water-quality issues in the regional study area. Creation of such a dataset for the regional study area would help to provide the kinds of information needed to characterize background conditions and the spatial and temporal variability in constituent concentrations associated with those conditions. Without such information, it is difficult to identify departures from background that might be associated with human activities.

Colorado↗
USGS2015

Integrated Environmental Modelling: Human decisions, human challenges

Integrated Environmental Modelling (IEM) is an invaluable tool for understanding the complex, dynamic ecosystems that house our natural resources and control our environments. Human behaviour affects the ways in which the science of IEM is assembled and used for meaningful societal applications. In particular, human biases and heuristics reflect adaptation and experiential learning to issues with frequent, sharply distinguished, feedbacks. Unfortunately, human behaviour is not adapted to the more diffusely experienced problems that IEM typically seeks to address. Twelve biases are identified that affect IEM (and science in general). These biases are supported by personal observations and by the findings of behavioural scientists. A process for critical analysis is proposed that addresses some human challenges of IEM and solicits explicit description of (1) represented processes and information, (2) unrepresented processes and information, and (3) accounting for, and cognizance of, potential human biases. Several other suggestions are also made that generally complement maintaining attitudes of watchful humility, open-mindedness, honesty and transparent accountability. These suggestions include (1) creating a new area of study in the behavioural biogeosciences, (2) using structured processes for engaging the modelling and stakeholder communities in IEM, and (3) using ‘red teams’ to increase resilience of IEM constructs and use.

Geological Society of London Special Publications↗
USGS1983

Geotherm: the U.S. geological survey geothermal information system

GEOTHERM is a comprehensive system of public databases and software used to store, locate, and evaluate information on the geology, geochemistry, and hydrology of geothermal systems. Three main databases address the general characteristics of geothermal wells and fields, and the chemical properties of geothermal fluids; the last database is currently the most active. System tasks are divided into four areas: (1) data acquisition and entry, involving data entry via word processors and magnetic tape; (2) quality assurance, including the criteria and standards handbook and front-end data-screening programs; (3) operation, involving database backups and information extraction; and (4) user assistance, preparation of such items as application programs, and a quarterly newsletter. The principal task of GEOTHERM is to provide information and research support for the conduct of national geothermal-resource assessments. The principal users of GEOTHERM are those involved with the Geothermal Research Program of the U.S. Geological Survey. Information in the system is available to the public on request. ?? 1983.

Computers & Geosciences↗
USGS2026

Indicators of mercury concentration in Lake Trout: Can fish location and appearance provide information to anglers to reduce their exposure?

Objective People are exposed to mercury (Hg) through the consumption of fish. State and federal governments provide broad, often-generalized food safety guidance to reduce exposure; however, numerous rural fishing areas lack testing and location- or species-specific guidance. The aim of this study was to provide tangible, visible, or easily measured characteristics of Lake Trout Salvelinus namaycush that could convey information on Hg exposure to people harvesting and consuming fish where no location-specific guidance exists. Methods We investigated potential indicators of Lake Trout total Hg (THg) concentrations in muscle across 10 lakes in Alaska's national parks. Potential indicators, including lake, lake zone (i.e., littoral, pelagic, profundal), fish length, head size, body condition, and general appearance, were evaluated by competing linear mixed-effects models. Results Lake Trout THg concentrations ranged widely from 22 to 1,306 ng/g wet weight. Much of the variation (48%) in THg concentrations was attributed to differences among individual lakes, but the interaction of the fish's lake zone, body length, and head size accounted for an additional 21%. Predicted THg concentrations increased with Lake Trout length and head : body proportion, but the rate of THg concentration increase with length varied by head : body proportion and lake zone. Conclusions Given the overwhelming evidence of high lake-to-lake variability in Lake Trout THg concentrations, we find support for use of lake-specific guidance when data are available. When lake-specific THg concentrations are not available, the best potential way to reduce exposure is to harvest and consume Lake Trout with mean predicted THg concentrations that are within state and federal safe consumption guidelines. This included Lake Trout from surface waters (i.e., pelagic or littoral zone) that are ≤70 cm in length; if harvesting fish from deep waters (i.e., profundal zone), lower THg concentrations were found in Lake Trout with heads ≤25% of their body length. The indicators—lake zone, length, and head size—of Lake Trout THg concentrations can provide harvesters with additional information in the absence of data for specific lakes.

Alaska↗
USGS1906

Geology of the Bighorn Mountains

This report is the result of studies made in the field during the seasons of 1901, 1902, 1903, 1904, and 1905. It relates to an area of about 9,000 square miles, situated mainly in the north-central portion of Wyoming and extending northward into Montana. Its location and general surroundings are shown on PL II. It covers the greater portion of the Bighorn uplift, together with an adjoining area of the Great Plains on the east. It also includes a small part of the Bighorn Basin and the eastern end of the Bridger Range. The report describes the various rocks, their structure, history, and mineral resources, including underground water, coal, gypsum, and various other products. It also contains information as to surface waters available for irrigation. Throughout the work assistance has been rendered by Mr. C. A. Fisher, who mapped portions of the area, measured numerous sections, collected fossils, and examined most of the crystalline rocks; and the author is indebted to Mr. Albert Johannsen for some of the petrographic descriptions. Previous observers have given but little information regarding the geology of the Bighorn Mountains, though Dr. F. V. Hayden ascertained the general relations of the uplift in his exploration of the Northwest, and Mr. George H. Eldridge, who crossed the range near Bald Mountain and southwest of Buffalo during the summer of 1893, described 0 some of the broader features of the geologic succession and structure in a remarkably comprehensive manner, considering how small an area he had the opportunity to examine. The Bighorn region is very thinly settled, there being no permanent habitations among the mountains, and it is but little visited by others than hunters, prospectors, and herders. There have recently been established two summer resorts in the mountains, and each year a larger number of persons visit the region. Unfortunately the mineral prospects have proved disappointing to the prospectors, and there appears to be but little promise that the area will become important on account of its mineral resources. In the Bridger uplift promising prospects of gold and copper have recently been discovered, which may prove of value. There are extensive, forests in the mountains, which are now included in a Government forest reserve, but their timber is not of great value. Much of the area below timber line contains an abundance of luxuriant grasses and other plants, which afford excellent pasturage for stock, and large herds of sheep and cattle are ranged in the region during the short summer season. Game is moderately abundant, and most of the streams contain large numbers of trout. The region is one of great interest geologically on account of its variety of sedimentary rocks, interesting structure, and remarkably instructive glacial features. The central area, with its high peaks, presents alpine scenery of notable character. Doubtless in the future the region will be extensively visited by tourists, hunters, and geologists.

Montana, Wyoming↗
USGS2016

Prospects and limitations of citizen science in invasive species management: A case study with Burmese pythons in Everglades National Park

Citizen-science programs have the potential to contribute to the management of invasive species, including Python molurus bivittatus (Burmese Python) in Florida. We characterized citizen-science–generated Burmese Python information from Everglades National Park (ENP) to explore how citizen science may be useful in this effort. As an initial step, we compiled and summarized records of Burmese Python observations and removals collected by both professional and citizen scientists in ENP during 2000–2014 and found many patterns of possible significance, including changes in annual observations and in demographic composition after a cold event. These patterns are difficult to confidently interpret because the records lack search-effort information, however, and differences among years may result from differences in search effort. We began collecting search-effort information in 2014 by leveraging an ongoing citizen-science program in ENP. Program participation was generally low, with most authorized participants in 2014 not searching for the snakes at all. We discuss the possible explanations for low participation, especially how the low likelihood of observing pythons weakens incentives to search. The monthly rate of Burmese Python observations for 2014 averaged ~1 observation for every 8 h of searching, but during several months, the rate was 1 python per >40 h of searching. These low observation-rates are a natural outcome of the snakes’ low detectability—few Burmese Pythons are likely to be observed even if many are present. The general inaccessibility of the southern Florida landscape also severely limits the effectiveness of using visual searches to find and remove pythons for the purposes of population control. Instead, and despite the difficulties in incentivizing voluntary participation, the value of citizen-science efforts in the management of the Burmese Python population is in collecting search-effort information.

Southeastern Naturalist↗
USGS2013

Center of Excellence for Geospatial Information Science research plan 2013-18

The U.S. Geological Survey Center of Excellence for Geospatial Information Science (CEGIS) was created in 2006 and since that time has provided research primarily in support of The National Map. The presentations and publications of the CEGIS researchers document the research accomplishments that include advances in electronic topographic map design, generalization, data integration, map projections, sea level rise modeling, geospatial semantics, ontology, user-centered design, volunteer geographic information, and parallel and grid computing for geospatial data from The National Map. A research plan spanning 2013–18 has been developed extending the accomplishments of the CEGIS researchers and documenting new research areas that are anticipated to support The National Map of the future. In addition to extending the 2006–12 research areas, the CEGIS research plan for 2013–18 includes new research areas in data models, geospatial semantics, high-performance computing, volunteered geographic information, crowdsourcing, social media, data integration, and multiscale representations to support the Three-Dimensional Elevation Program (3DEP) and The National Map of the future of the U.S. Geological Survey.

Open-File Report↗
USGS2006

Preliminary integrated geologic map databases for the United States: Digital data for the generalized bedrock geologic map, Yukon Flats region, east-central Alaska

The growth in the use of Geographic Information Systems (GIS) has highlighted the need for digital geologic maps that have been attributed with information about age and lithology. Such maps can be conveniently used to generate derivative maps for manifold special purposes such as mineral-resource assessment, metallogenic studies, tectonic studies, and environmental research. This report is part of a series of integrated geologic map databases that cover the entire United States. Three national-scale geologic maps that portray most or all of the United States already exist; for the conterminous U.S., King and Beikman (1974a,b) compiled a map at a scale of 1:2,500,000, Beikman (1980) compiled a map for Alaska at 1:2,500,000 scale, and for the entire U.S., Reed and others (2005a,b) compiled a map at a scale of 1:5,000,000. A digital version of the King and Beikman map was published by Schruben and others (1994). Reed and Bush (2004) produced a digital version of the Reed and others (2005a) map for the conterminous U.S. The present series of maps is intended to provide the next step in increased detail. State geologic maps that range in scale from 1:100,000 to 1:1,000,000 are available for most of the country, and digital versions of these state maps are the basis of this product. The digital geologic maps presented here are in a standardized format as ARC/INFO export files and as ArcView shape files. Data tables that relate the map units to detailed lithologic and age information accompany these GIS files. The map is delivered as a set 1:250,000-scale quadrangle files. To the best of our ability, these quadrangle files are edge-matched with respect to geology. When the maps are merged, the combined attribute tables can be used directly with the merged maps to make derivative maps.

Alaska↗