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At least 235 records · Page 13Linked to original sources
USGS2010

Volcanic hazards and their mitigation: progress and problems

At the beginning of the twentieth century, volcanology began to emerge as a modern science as a result of increased interest in eruptive phenomena following some of the worst volcanic disasters in recorded history: Krakatau (Indonesia) in 1883 and Mont Pelée (Martinique), Soufrière (St. Vincent), and Santa María (Guatemala) in 1902. Volcanology is again experiencing a period of heightened public awareness and scientific growth in the 1980s, the worst period since 1902 in terms of volcanic disasters and crises. A review of hazards mitigation approaches and techniques indicates that significant advances have been made in hazards assessment, volcano monitoring, and eruption forecasting. For example, the remarkable accuracy of the predictions of dome-building events at Mount St. Helens since June 1980 is unprecedented. Yet a predictive capability for more voluminous and explosive eruptions still has not been achieved. Studies of magma-induced seismicity and ground deformation continue to provide the most systematic and reliable data for early detection of precursors to eruptions and shallow intrusions. In addition, some other geophysical monitoring techniques and geochemical methods have been refined and are being more widely applied and tested. Comparison of the four major volcanic disasters of the 1980s (Mount St. Helens, U.S.A. (1980), El Chichón, Mexico (1982); Galunggung, Indonesia (1982); and Nevado del Ruíz, Colombia (1985) illustrates the importance of predisaster geoscience studies, volcanic hazards assessments, volcano monitoring, contingency planning, and effective communications between scientists and authorities. The death toll (>22,000) from the Ruíz catastrophe probably could have been greatly reduced; the reasons for the tragically ineffective implementation of evacuation measures are still unclear and puzzling in view of the fact that sufficient warnings were given. The most pressing problem in the mitigation of volcanic and associated hazards on a global scale is that most of the world's dangerous volcanoes are in densely populated countries that lack the economic and scientific resources or the political will to adequately study and monitor them. This problem afflicts both developed and developing countries, but it is especially acute for the latter. The greatest advances in volcanic hazards mitigation in the near future are most likely to be achieved by wider application of existing technology to poorly understood and studied volcanoes, rather than by refinements or new discoveries in technology alone.

Reviews of Geophysics↗
USGS2004

Tigers and their prey: Predicting carnivore densities from prey abundance

The goal of ecology is to understand interactions that determine the distribution and abundance of organisms. In principle, ecologists should be able to identify a small number of limiting resources for a species of interest, estimate densities of these resources at different locations across the landscape, and then use these estimates to predict the density of the focal species at these locations. In practice, however, development of functional relationships between abundances of species and their resources has proven extremely difficult, and examples of such predictive ability are very rare. Ecological studies of prey requirements of tigers Panthera tigris led us to develop a simple mechanistic model for predicting tiger density as a function of prey density. We tested our model using data from a landscape-scale long-term (1995-2003) field study that estimated tiger and prey densities in 11 ecologically diverse sites across India. We used field techniques and analytical methods that specifically addressed sampling and detectability, two issues that frequently present problems in macroecological studies of animal populations. Estimated densities of ungulate prey ranged between 5.3 and 63.8 animals per km 2 . Estimated tiger densities (3.2-16.8 tigers per 100 km 2 ) were reasonably consistent with model predictions. The results provide evidence of a functional relationship between abundances of large carnivores and their prey under a wide range of ecological conditions. In addition to generating important insights into carnivore ecology and conservation, the study provides a potentially useful model for the rigorous conduct of macroecological science.

Proceedings of the National Academy of Sciences↗
USGS2011

Implementation of unmanned aircraft systems by the U.S. Geological Survey

The U.S. Geological Survey (USGS) Unmanned Aircraft Systems (UAS) Project Office is leading the implementation of UAS technology in anticipation of transforming the research methods and management techniques employed across the Department of the Interior. UAS technology is being made available to monitor environmental conditions, analyse the impacts of climate change, respond to natural hazards, understand landscape change rates and consequences, conduct wildlife inventories and support related land management missions. USGS is teaming with the Department of the Interior Aviation Management Directorate (AMD) to lead the safe and cost-effective adoption of UAS technology by the Department of the Interior Agencies and USGS scientists.

Geocarto International↗
USGS2026

Biological, environmental, and geomorphological factors influencing reach-specific survival of spring Chinook Salmon smolts upstream of the Columbia–Snake River hydrosystem

Objective Pacific salmon Oncorhynchus spp. are exhibiting catastrophic declines throughout much of the Pacific Northwest, and juvenile mortality contributions are disproportionately high. Many Pacific salmon smolt populations are exhibiting high natal stream mortality; however, detailed natal stream reach-specific survival knowledge is lacking. Our objectives were to estimate natal stream reach-specific survival and identify influential covariates for spring Chinook Salmon O. tshawytscha smolts. An additional objective was to evaluate (i.e., estimate postrestoration cumulative survival) a novel and strategic large-scale river restoration approach (i.e., stream confluence restoration) in two Pacific Northwest spring Chinook Salmon natal streams. Methods Using radiotelemetry techniques during March–June (2011–2017), we estimated natal stream reach-specific survival for spring Chinook Salmon smolts in Catherine Creek and the Grande Ronde River, northeast Oregon. We examined the interrelated influences of temporal, biological, environmental, and geomorphological covariates on the behavior, travel time, and reach-specific survival of spring Chinook Salmon smolts that were emigrating through two hydrologically altered natal streams in the interior Columbia River basin. For each natal stream smolt tag-group, Cormack–Jolly–Seber reach-specific survival estimates that were adjusted for premature tag failure (i.e., bias-corrected) were generated. Subsequently, smolt effects were estimated using reach-specific travel times and survival estimates coupled with individual time-varying covariates from radio-tagged smolts and occupied reaches using an existing predator–prey model (i.e., mean free-path length [ XT ] model). Complementary population-specific principal coordinate analyses (PCoAs) were conducted to facilitate visualization of multicovariate resemblances in ordination space. Last, we employed our best-fitting XT model to model cumulative changes in smolt survival that were associated with a large-scale stream channel restoration scenario (i.e., restoration of the historical Catherine Creek and Grande Ronde River confluence). Results In aggregate, Catherine Creek smolts exhibited high mortality throughout Catherine Creek but near-100% survival upon entering the Grande Ronde River. In contrast, Grande Ronde River smolts generally exhibited low mortality upstream from the Grande Ronde Valley and high mortality throughout the Grande Ronde Valley. Our best-fitting XT model indicated that smolt survival was positively correlated with discharge, body size, and current velocity but negatively correlated with avian predation. Natural-origin smolts from Catherine Creek displayed higher λ-values (i.e., distance between predator–prey encounters) than their significantly larger and faster emigrating hatchery conspecifics, indicating that hatchery smolts may be more susceptible to predation. Our population-specific PCoAs further revealed that novel water (i.e., unique water chemistry) and emigration rate were the strongest predictors of reach occupancy in multivariate ordination space. Under a stream restoration scenario of restoring the historical hydrological template (i.e., restored channel configuration), our best-fitting XT model predicted changes in population-specific cumulative survivals to the lower Grande Ronde Valley (Imbler, Oregon) ranging from −38.4% to 69.0% for Grande Ronde River and Catherine Creek spring Chinook Salmon smolts, respectively. Conclusions Our best-fitting XT model and PCoAs identified the relative importance of biological, environmental, and geomorphological factors to both natural- and hatchery-origin Chinook Salmon smolt survival in two neighboring interior natal streams in the Columbia River basin. Our research indicates that concurrent habitat restoration and fish management strategies, including focused attention on smolt-rearing nursery habitat restoration, piscivorous avian control plans, adaptive management strategies for hatchery smolt releases, and discharge and novel water regime restoration projects, may yield survival benefits to “in-basin” Chinook Salmon smolts. Our research can inform origin-type-specific Chinook Salmon smolt management, habitat restoration, and future research decisions throughout the upper Grande Ronde River subbasin and potentially the Pacific Northwest.

Oregon, Washington↗
USGS2006

A method to directly measure maximum volume of fish stomachs or digestive tracts

A new method for measuring maximum stomach or digestive tract volume of fish incorporates air injection at constant pressure with water displacement to measure directly the internal volume of a stomach or analogous structure. The method was tested with coho salmon, Oncorhynchus kisutch (Walbaum), which has a true stomach, and northern squawfish, Ptychocheilus oregonensis (Richardson), which has a modified foregut as a functional analogue. Both species were collected during July-October 1987 from the Columbia River, U.S.A. Relationships between fish weight (= volume) and maximum volume of the digestive organ were best fitted for coho salmon by an allometric model and for northern squawfish by an exponential model. Least squares regression analysis of individual measurements showed less variability in the volume of coho salmon stomachs ( R 2 = 0.85) than in the total digestive tracts ( R 2 = 0.55) and foreguts ( R 2 = 0.61) of northern squawfish, relative to fish size. Compared to previous methods, the new technique has the advantage of accurately measuring the internal volume of a wide range of digestive organ shapes and sizes.

Journal of Fish Biology↗
USGS2015

Evaluating unsupervised methods to size and classify suspended particles using digital in-line holography

Substantial information can be gained from digital in-line holography of marine particles, eliminating depth-of-field and focusing errors associated with standard lens-based imaging methods. However, for the technique to reach its full potential in oceanographic research, fully unsupervised (automated) methods are required for focusing, segmentation, sizing and classification of particles. These computational challenges are the subject of this paper, in which we draw upon data collected using a variety of holographic systems developed at Plymouth University, UK, from a significant range of particle types, sizes and shapes. A new method for noise reduction in reconstructed planes is found to be successful in aiding particle segmentation and sizing. The performance of an automated routine for deriving particle characteristics (and subsequent size distributions) is evaluated against equivalent size metrics obtained by a trained operative measuring grain axes on screen. The unsupervised method is found to be reliable, despite some errors resulting from over-segmentation of particles. A simple unsupervised particle classification system is developed, and is capable of successfully differentiating sand grains, bubbles and diatoms from within the surf-zone. Avoiding miscounting bubbles and biological particles as sand grains enables more accurate estimates of sand concentrations, and is especially important in deployments of particle monitoring instrumentation in aerated water. Perhaps the greatest potential for further development in the computational aspects of particle holography is in the area of unsupervised particle classification. The simple method proposed here provides a foundation upon which further development could lead to reliable identification of more complex particle populations, such as those containing phytoplankton, zooplankton, flocculated cohesive sediments and oil droplets.

Journal of Atmospheric and Oceanic Technology↗
USGS2016

Flexible characterization of animal movement pattern using net squared displacement and a latent state model

Background Characterizing the movement patterns of animals is an important step in understanding their ecology. Various methods have been developed for classifying animal movement at both coarse (e.g., migratory vs. sedentary behavior) and fine (e.g., resting vs. foraging) scales. A popular approach for classifying movements at coarse resolutions involves fitting time series of net-squared displacement (NSD) to models representing different conceptualizations of coarse movement strategies (i.e., migration, nomadism, sedentarism, etc.). However, the performance of this method in classifying actual (as opposed to simulated) animal movements has been mixed. Here, we develop a more flexible method that uses the same NSD input, but relies on an underlying discrete latent state model. Using simulated data, we first assess how well patterns in the number of transitions between modes of movement and the duration of time spent in a mode classify movement strategies. We then apply our approach to elucidate variability in the movement strategies of eight giant tortoises ( Chelonoidis sp.) using a multi-year (2009–2014) GPS dataset from three different Galapagos Islands. Results With respect to patterns of time spent and the number of transitions between modes, our approach out-performed previous efforts to distinguish among migration, dispersal, and sedentary behavior. We documented marked inter-individual variation in giant tortoise movement strategies, with behaviors indicating migration, dispersal, nomadism and sedentarism, as well as hybrid behaviors such as “exploratory residence”. Conclusions Distilling complex animal movement into discrete modes remains a fundamental challenge in movement ecology, a problem made more complex by the ever-longer duration, ever-finer resolution, and gap-ridden trajectories recorded by GPS devices. By clustering into modes, we derived information on the time spent within one mode and the number of transitions between modes which enabled finer differentiation of movement strategies over previous methods. Ultimately, the techniques developed here address limitations of previous approaches and provide greater insights with respect to characterization of movement strategies across scales by more fully utilizing long-term GPS telemetry datasets.

Movement Ecology↗
USGS1980

Digital terrain tapes: user guide

DMATC's digital terrain tapes are a by-product of the agency's efforts to streamline the production of raised-relief maps. In the early 1960's DMATC developed the Digital Graphics Recorder (DGR) system that introduced new digitizing techniques and processing methods into the field of three-dimensional mapping. The DGR system consisted of an automatic digitizing table and a computer system that recorded a grid of terrain elevations from traces of the contour lines on standard topographic maps. A sequence of computer accuracy checks was performed and then the elevations of grid points not intersected by contour lines were interpolated. The DGR system produced computer magnetic tapes which controlled the carving of plaster forms used to mold raised-relief maps. It was realized almost immediately that this relatively simple tool for carving plaster molds had enormous potential for storing, manipulating, and selectively displaying (either graphically or numerically) a vast number of terrain elevations. As the demand for the digital terrain tapes increased, DMATC began developing increasingly advanced digitizing systems and now operates the Digital Topographic Data Collection System (DTDCS). With DTDCS, two types of data elevations as contour lines and points, and stream and ridge lines are sorted, matched, and resorted to obtain a grid of elevation values for every 0.01 inch on each map (approximately 200 feet on the ground). Undefined points on the grid are found by either linear or or planar interpolation.

Report↗
USGS1979

Initial report of the Petrophysics Laboratory

Current national requirements for energy and mineral resources, and for protection of the quality of the environment, have focused attention on the need to develop new methods and interpretation techniques to be used in understanding geologic systems. Geophysical surveys play a significant role in acquiring this information, particularly by providing data in the third dimension--at depth beneath the surface.

Circular↗
USGS2001

MODFLOW-2000 : the U.S. Geological Survey modular ground-water model--documentation of the Advective-Transport Observation (ADV2) Package

Observations of the advective component of contaminant transport in steady-state flow fields can provide important information for the calibration of ground-water flow models. This report documents the Advective-Transport Observation (ADV2) Package, version 2, which allows advective-transport observations to be used in the three-dimensional ground-water flow parameter-estimation model MODFLOW-2000. The ADV2 Package is compatible with some of the features in the Layer-Property Flow and Hydrogeologic-Unit Flow Packages, but is not compatible with the Block-Centered Flow or Generalized Finite-Difference Packages. The particle-tracking routine used in the ADV2 Package duplicates the semi-analytical method of MODPATH, as shown in a sample problem. Particles can be tracked in a forward or backward direction, and effects such as retardation can be simulated through manipulation of the effective-porosity value used to calculate velocity. Particles can be discharged at cells that are considered to be weak sinks, in which the sink applied does not capture all the water flowing into the cell, using one of two criteria: (1) if there is any outflow to a boundary condition such as a well or surface-water feature, or (2) if the outflow exceeds a user specified fraction of the cell budget. Although effective porosity could be included as a parameter in the regression, this capability is not included in this package. The weighted sum-of-squares objective function, which is minimized in the Parameter-Estimation Process, was augmented to include the square of the weighted x-, y-, and z-components of the differences between the simulated and observed advective-front locations at defined times, thereby including the direction of travel as well as the overall travel distance in the calibration process. The sensitivities of the particle movement to the parameters needed to minimize the objective function are calculated for any particle location using the exact sensitivity-equation approach; the equations are derived by taking the partial derivatives of the semi-analytical particle-tracking equation with respect to the parameters. The ADV2 Package is verified by showing that parameter estimation using advective-transport observations produces the true parameter values in a small but complicated test case when exact observations are used. To demonstrate how the ADV2 Package can be used in practice, a field application is presented. In this application, the ADV2 Package is used first in the Sensitivity-Analysis mode of MODFLOW-2000 to calculate measures of the importance of advective-transport observations relative to head-dependent flow observations when either or both are used in conjunction with hydraulic-head observations in a simulation of the sewage-discharge plume at Cape Cod, Massachusetts. The ADV2 Package is then used in the Parameter-Estimation mode of MODFLOW-2000 to determine best-fit parameter values. It is concluded that, for this problem, advective-transport observations improved the calibration of the model and the estimation of ground-water flow parameters, and the use of formal parameter-estimation methods and related techniques produced significant insight into the physical system.

Open-File Report↗
USGS2007

Applying radar technology to migratory bird conservation and management: Strengthening and expanding a collaborative

Executive Summary Understanding the factors affecting migratory bird and bat populations during all three phases of their life cycle—breeding, nonbreeding, and migration—is critical to species conservation planning. This includes the need for information about these species’ responses to natural challenges, as well as information about the effects of human activities and structures. Habitats and other resources critical to migrants during passage and stopover are being destroyed, degraded, and threatened by human activities. Birds and bats are also uniquely susceptible to human use of the airspace. Wind turbines, communication and power transmission towers, and other tall structures, known to cause bird and bat mortality, are being erected or proposed in increasing numbers across the country. In addition, the potential for bird/aircraft collisions poses human safety threats. Management and regulatory agencies, conservation organizations, and industry currently lack the information they need to meet their missions and statutory responsibilities. The biological data available from various radar technologies offer a unique opportunity to learn more about the spatiotemporal distribution patterns, flight characteristics, and habitat use of “aero-fauna.” Recognizing the opportunities presented by radar technologies, the U.S. Geological Survey (USGS), the U.S. Fish and Wildlife Service (USFWS), and university partners collaborated first on individual projects and then in a broader, informal “collaborative” to coordinate their radar-related research and work together to develop the suite of products needed for conservation of birds and bats. Having produced two summary documents (Sojda and others, 2005; Ruth and others, 2005), the next objective was to convene a workshop for researchers, management and regulatory agencies, and other interested parties. The focus of this initial workshop was on strengthening the existing USGS-USFWS-university partnership and expanding the “collaborative” to include new Federal agency partners. The subject matter was centered on discussing available technologies, appropriate applications, management-related needs, and ways to strengthen collaborative research and conservation efforts. The workshop opened with presentations about the history of the “radar collaborative,” a description of the workshop objectives and focuses, and a summary of resource management and regulatory needs. Scientific presentations describing current research projects or subjects followed, given by USGS scientists, as well as scientists from other Federal agencies, academia, conservation and ornithological organizations, and a private contracting firm. Presenters addressed a wide variety of management issues including siting of wind-power facilities, bird/aircraft collisions, effects of hurricanes Katrina and Rita on bird migration, bird use of Conservation Reserve Program land, defining bird migration patterns at a broad regional scale, and associating migrant birds with their stopover habitats. Presentations described a variety of radar technologies including NEXRAD weather surveillance radar, modified mobile marine radar, military tracking radar, pencil beam radar, and dual polarization radar, as well as complementary techniques and analysis methods such as acoustic monitoring, thermal imaging, artificial intelligence, and individual-based modeling. Key issues, themes, and questions identified during the open discussions that followed fell into five main categories: (1) agency needs and challenges; (2) radar technology and applications—technical questions and issues; (3) tools and resources for managers and researchers; (4) standardization of protocols; and (5) collaborative opportunities. Participants identified the following management, regulatory, or business issues facing them which may be addressed with radar technologies: tall structures; wind turbines; identification and protection of key habitats; assessment of management activities; and bird/aircraft strikes. Participants frequently expressed the need for specific information about which radar technologies are best used for answering particular questions. User groups emphasized the importance of clear, defensible scientific information on which they can base their activities. In turn, researchers emphasized their need for clearly defined, specific questions from managers so that they can design and conduct the required research. Discussions about technical issues requiring further research and collaboration included target identity, ground-truthing, linking migrants to habitat, and standardized protocols for applied research. Workshop participants identified and endorsed a series of seven action items that would promote collaboration and begin to address key issues identified at the workshop: Action Item #1 : Establish a working subgroup to address large-scale surveillance radar standardization issues. Action Item #2 : Establish a working subgroup to address small-scale radar standardization issues. Action Item #3 : Bring management and regulatory agencies together to identify the three most important information needs for each key management issue relating to radar technologies. Action Item #4 : Develop Fact Sheet(s) to provide information about radar technology applications to migratory bird and bat conservation issues. Action Item #5 : Create a “radar collaborative” Website to provide information about radar biology applications, contacts, publications, and so forth. Action Item #6 : Formalize and expand the USGS-USFWS “radar collaborative.” Action Item #7 : Advance basic research, such as target identity and validation, which will support and improve our abilities to apply radar technologies to conservation objectives. There was considerable interest in expanding the “radar collaborative” to include those agencies, organizations, and industries represented at the workshop. It was felt that the publication of the workshop proceedings, implementation of action items, and additional future meetings or workshops will be crucial in strengthening the “radar collaborative” effort and promoting the use of these valuable technologies for conserving migratory species.

Open-File Report↗
USGS1996

Hydrologic and water-quality data for two small watersheds on Catoctin Mountain, North-Central Maryland, 1987-93

Hydrologic and water-quality data were collected from a precipitation-collection station and from two small watersheds on Catoctin Mountain, north-central Maryland, as part of investigations of acidic deposition and episodic acidification, and their effects on streamwater quality. Detailed descriptions of the site instrumentation in the watersheds, field data-collection techniques, and laboratory methods used to conduct the studies are included. Data that were collected on precipitation, throughfall, soil water, ground water, streamwater, and other surface and ground waters sampled during biannual synoptic surveys are given in tables. Data collected since October 1987 from one of the streamwater-quality monitoring sites and data collected since March 1988 from one of the ground-water quality monitoring sites are presented. Additional data collected since January 1987 from the precipitation station and data collected since June 1990 from all of the other water-quality monitoring sites are presented. Hydrologic data include tables of precipitation and throughfall quantities, streamflow, and synoptic measurements of ground-water levels. Selected hydrologic data are shown in graphs.

Maryland↗
USGS2011

Borehole geophysical investigation of a formerly used defense site, Machiasport, Maine, 2003-2006

The U.S. Geological Survey, in cooperation with the U.S. Army Corps of Engineers, collected borehole geophysical logs in 18 boreholes and interpreted the data along with logs from 19 additional boreholes as part of an ongoing, collaborative investigation at three environmental restoration sites in Machiasport, Maine. These sites, located on hilltops overlooking the seacoast, formerly were used for military defense. At each of the sites, chlorinated solvents, used as part of defense-site operations, have contaminated the fractured-rock aquifer. Borehole geophysical techniques and hydraulic methods were used to characterize bedrock lithology, fractures, and hydraulic properties. In addition, each geophysical method was evaluated for effectiveness for site characterization and for potential application for further aquifer characterization and (or) evaluation of remediation efforts. Results of borehole geophysical logging indicate the subsurface is highly fractured, metavolcanic, intrusive, metasedimentary bedrock. Selected geophysical logs were cross-plotted to assess correlations between rock properties. These plots included combinations of gamma, acoustic reflectivity, electromagnetic induction conductivity, normal resistivity, and single-point resistance. The combined use of acoustic televiewer (ATV) imaging and natural gamma logs proved to be effective for delineating rock types. Each of the rock units in the study area could be mapped in the boreholes, on the basis of the gamma and ATV reflectivity signatures. The gamma and mean ATV reflectivity data were used along with the other geophysical logs for an integrated interpretation, yielding a determination of quartz monzonite, rhyolite, metasedimentary units, or diabase/gabbro rock types. The interpretation of rock types on the basis of the geophysical logs compared well to drilling logs and geologic mapping. These results may be helpful for refining the geologic framework at depth. A stereoplot of all fractures intersecting the boreholes indicates numerous fractures, a high proportion of steeply dipping fractures, and considerable variation in fracture orientation. Low-dip-angle fractures associated with unloading and exfoliation are also present, especially at a depth of less than 100 feet below the top of casing. These sub-horizontal fractures help to connect the steeply dipping fractures, making this a highly connected fracture network. The high variability in the fracture orientations also increases the connectivity of the fracture network. A preliminary comparison of all fracture data from all the boreholes suggests fracturing decreases with depth. Because all the boreholes were not drilled to the same depth, however, there is a clear sampling bias. Hence, the deepest boreholes are analyzed separately for fracture density. For the deepest boreholes in the study, the intensity of fracturing does not decline significantly with depth. It is possible the fractures observed in these boreholes become progressively tighter or closed with depth, but this is difficult to verify with the borehole methods used in this investigation. The fact that there are more sealed fractures at depth (observed in optical televiewer logs in some of the boreholes) may indicate less opening of the sealed fractures, less water moving through the rock, and less weathering of the fracture infilling minerals. Although the fracture orientation remained fairly constant with depth, differences in the fracture patterns for the three restoration sites indicate the orientation of fractures varies across the study area. The fractures in boreholes on Miller Mountain predominantly strike northwest-southeast, and to a lesser degree they strike northeast. The fractures on or near the summit of Howard Mountain strike predominantly east-west and dip north and south, and the fractures near the Transmitter Site strike northeast-southwest and dip northwest and southeast. The fracture populations for the boreholes on or near the summit of Howard Mountain show more variation than at the other two sites. This variation may be related to the proximity of the fault, which is northeast of the summit of Howard Mountain. In a side-by-side comparison of stereoplots from selected boreholes, there was no clear correspondence between fracture orientation and proximity to the fault. There is, however, a difference in the total populations of fractures for the boreholes on or near the summit of Howard Mountain and the boreholes near the Transmitter Site. Further to the southwest and further away from the fault, the fractures at the Transmitter Site predominantly strike northeast-southwest and northwest-southeast.Heat-pulse flowmeter (HPFM) logging was used to identify transmissive fractures and to estimate the hydraulic properties along the boreholes. Ambient downflow was measured in 13 boreholes and ambient upflow was measured in 9 boreholes. In nine other bedrock boreholes, the HPFM did not detect measurable vertical flow. The observed direction of vertical flow in the boreholes generally was consistent with the conceptual flow model of downward movement in recharge locations and upward flow in discharge locations or at breaks in the slope of land surface. Under low-rate pumping or injection rates [0.25 to 1 gallon per minute (gal/min)], one to three inflow zones were identified in each borehole. Two limitations of HPFM methods are (1) the HPFM can only identify zones within 1.5 to 2 orders of magnitude of the most transmissive zone in each borehole, and (2) the HPFM cannot detect flow rates less than 0.010 + or - 0.005 gal/min, which corresponds to a transmissivity of about 1 foot squared per day (ft2/d). Consequently, the HPFM is considered an effective tool for identifying the most transmissive fractures in a borehole, down to its detection level. Transmissivities below that cut-off must be measured with another method, such as packer testing or fluid-replacement logging. Where sufficient water-level and flowmeter data were available, HPFM results were numerically modeled. For each borehole model, the fracture location and measured flow rates were specified, and the head and transmissivity of each fracture zone were adjusted until a model fit was achieved with the interpreted ambient and stressed flow profiles. The transmissivities calculated by this method are similar to the results of an open-hole slug test; with the added information from the flowmeter, however, the head and transmissivity of discrete zones also can be determined. The discrete-interval transmissivities ranged from 0.16 to 330 ft2/d. The flowmeter-derived open-hole transmissivity, which is the combined total of each of the transmissive zones, ranged from 1 to 511 ft2/d. The whole-well open-hole transmissivity values determined with HPFM methods were compared to the results of open-hole hydraulic tests. Despite the fact that the flowmeter-derived transmissivities consistently were lower than the estimates derived from open-hole hydraulic tests alone, the correlation was very strong (with a coefficient of determination, R2, of 0.9866), indicating the HPFM method provides a reasonable estimate of transmissivities for the most transmissive fractures in the borehole. Geologic framework, fracture characterization, and estimates of hydraulic properties were interpreted together to characterize the fracture network. The data and interpretation presented in this report should provide information useful for site investigators as the conceptual site groundwater flow model is refined. Collectively, the results and the conceptual site model are important for evaluating remediation options and planning or implementing the design of a well field and borehole completions that will be adequate for monitoring flow, remediation efforts, groundwater levels, and (or) water quality. Similar kinds of borehole geophysical logging (specifically the borehole imaging, gamma, fluid logs, and HPFM) should be conducted in any newly installed boreholes and integrated with interpretations of any nearby boreholes. If boreholes are installed close to existing or other new boreholes, cross-hole flowmeter surveys may be appropriate and may help characterize the aquifer properties and connections between the boreholes.

Maine↗
USGS2014

Development of a regionally consistent geospatial dataset of agricultural lands in the Upper Colorado River Basin, 2007-10

Irrigation in arid environments can alter the natural rate at which salts are dissolved and transported to streams. Irrigated agricultural lands are the major anthropogenic source of dissolved solids in the Upper Colorado River Basin (UCRB). Understanding the location, spatial distribution, and irrigation status of agricultural lands and the method used to deliver water to agricultural lands are important to help improve the understanding of agriculturally derived dissolved-solids loading to surface water in the UCRB. Irrigation status is the presence or absence of irrigation on an agricultural field during the selected growing season or seasons. Irrigation method is the system used to irrigate a field. Irrigation method can broadly be grouped into sprinkler or flood methods, although other techniques such as drip irrigation are used in the UCRB. Flood irrigation generally causes greater dissolved-solids loading to streams than sprinkler irrigation. Agricultural lands in the UCRB mapped by state agencies at varying spatial and temporal resolutions were assembled and edited to represent conditions in the UCRB between 2007 and 2010. Edits were based on examination of 1-meter resolution aerial imagery collected between 2009 and 2011. Remote sensing classification techniques were used to classify irrigation status for the June to September growing seasons between 2007 and 2010. The final dataset contains polygons representing approximately 1,759,900 acres of agricultural lands in the UCRB. Approximately 66 percent of the mapped agricultural lands were likely irrigated during the study period.

Arizona, Colorado, New Mexico, Utah, Wyoming↗
USGS2005

Borehole-geophysical and hydraulic investigation of the fractured-rock aquifer near the University of Connecticut Landfill, Storrs, Connecticut, 2000 to 2001

An integrated borehole-geophysical and hydraulic investigation was conducted at the former landfill area near the University of Connecticut in Storrs, Connecticut, where solvents and landfill leachate have contaminated a fractured-bedrock aquifer. Borehole-geophysical techniques and hydraulic methods were used to characterize the site bedrock lithology and structure, fractures, and hydraulic properties. The geophysical and hydraulic methods included conventional logs, borehole imaging, borehole radar, flowmeter under ambient- and stressed hydraulic conditions, and discrete-zone hydraulic testing, sampling, and monitoring. The conventional geophysical-logging methods included caliper, deviation, electromagnetic induction, gamma, specific conductance, and fluid temperature. The advanced methods included optical and acoustic imaging of the borehole wall, heat-pulse flowmeter, and directional radar reflection. Borehole-geophysical methods were used to further define conductive features identified with surface-geophysical methods in the first phase of the investigation. The results of the surface- and borehole-geophysical logging were evaluated in an iterative and integrated manner to develop a conceptual model of ground-water flow at the site. The rock type, foliation, and fractures at the site were characterized from high-resolution optical televiewer (OTV) images of rocks penetrated by the boreholes and were compared to drilling logs and conventional geophysical logs. The rocks are interpreted as fine- to mediumgrained quartz-feldspar-biotite-garnet gneiss and schist with local intrusions of quartz diorite and pegmatite and minor concentrations of sulfide mineralization similar to rocks described as the Bigelow Brook Formation on regional geologic maps. Layers containing high concentrations of sulfide minerals appear as high electrical conductivity zones on electromagnetic-induction and borehole-radar logs. Foliation in the rocks generally strikes to the southwest and northeast, and dips to the northwest and southeast consistent with previous investigations in this area. The orientation of foliation, however, varies locally and with depth in some of the boreholes. These results are consistent with geologic mapping that has identified small-scale folding. The orientations of the transmissive fractures identified in the six boreholes logged for this investigation are similar to the fracture orientations mapped in a previous investigation. Many of these fractures are oriented with a north-northwest strike and have a shallow dip to the west. Other transmissive fractures have a southwest strike and dip at shallow angles to the northwest, and some strike roughly east-west and dip to the north and south. Flowmeter logging was used to identify transmissive fractures and to estimate the hydraulic properties in the boreholes. Ambient down flow was measured in one borehole, and ambient up flow and down flow were measured in another borehole. The other four bedrock boreholes did not have measurable vertical flow. Under low-rate pumping conditions (0.25 to 0.5 gallons per minute), one to three inflow zones were identified in each well. Commonly, fractures that are active under ambient conditions contribute to the well under pumping conditions. The ambient conditions were incorporated into the determination of the relative proportions of transmissivity. Specific capacity and transmissivity were determined for these open-hole low-rate pumping tests. Quasi-steady-state water levels were reached in four of the boreholes, including MW201R, MW204R, MW302R, and W202-NE. When pumped at low-rate conditions for 0.5 to 4 hours, the specific capacity ranged from 0.03 to 0.18 gallons per minute per foot. The open-hole transmissivity estimates ranged from 4.9 to 30 feet squared per day (ft2/d). Open-hole transmissivity was determined for boreholes that did not reach quasi-steady-state conditions under low-rate pumping conditions. Transmissivity was estimated for MW201R, MW202R, and MW203R using non-equilibrium methods, pumping rate, and the transient drawdown data to estimate the open-hole transmissivity. Transmissivity in these boreholes ranged from 0.98 to 3.2 ft 2 /d. The transmissivity and head of individual fractures or zones of fractures were estimated from heat-pulse flowmeter data acquired under ambient and stressed conditions. In the absence of ambient flow, data from two profiles of heat-pulse flowmeter data under two different stressed conditions were used to estimate the transmissivity and head of individual fracture zones. Only two boreholes, MW302R and W202-NE, had sufficient data for these analyses. The estimated transmissivity of individual transmissive zones ranged from 1.2 to 9.2 ft 2 /d. The transmissivity values determined by this numerical simulation method were less than the open-hole estimations, which were 15 and 30 ft 2 /d. Transmissivity also was measured directly over discrete intervals of the borehole using a straddle-packer apparatus and constant-rate pumping tests. Pumping rates were less than or equal to 0.25 gallons per minute. These discretezone single-hole pumping tests were conducted over a short period of time, usually about 30 minutes to 1 hour in duration. Pumping continued until the test zone reached a steady-state water level or until it was determined that the zone could not yield water at the pumped rate. The estimated transmissivity of individual transmissive zones ranged from about 0.21 to 11 ft 2 /d. The zone at a depth of 197 feet in W202-NE was the only zone that had discrete-interval testing with a straddle packer and sufficient heat-pulse flowmeter data for modeling the flow and estimating transmissivity and head. The two methods produced similar results. The straddle-packer method estimated a transmissivity of 4.7 ft 2 /d, and the heat-pulse flowmeter modeling results estimated a transmissivity of 6.9 ft 2 /d. A comparison of the transmissivity estimates indicate estimates typically are within an order of magnitude. The heat-pulse flowmeter methods used in this investigation to determine transmissivity of the boreholes and the individual fractures measure only the upper two or three orders of magnitude of transmissivity. Hence, other fractures in these boreholes permit the movement of water; their transmissivities, however, are lower than the detection limits of the methods that were used for this investigation and very small compared to the transmissive fractures that were studied. The data collected in this investigation were used to design discrete-zone monitoring systems for four of the boreholes used for monitoring. The results of the investigation are useful for refining the conceptual site model of ground-water flow, and for providing critical information for interpreting the results of water-quality sampling.

Connecticut↗
USGS1996

Hydrologic and geochemical factors affecting the chemistry of small headwater streams in response to acidic deposition on Catoctin Mountain, north-central Maryland

Hydrologic and water-quality data were collected at a precipitation-collection station and from two small watersheds on Catoctin Mountain, north- central Maryland, as part of an investigation of episodic acidification and its effects on streamwater quality. Data were collected from June 1990 through December 1993. Descriptions of the water shed instrumentation, data-collection techniques, and laboratory methods used to conduct the studies are included. Data that were collected on precipitation, throughfall, soil water, ground water, and streamwater during base flow and stormflow indicate that the streams undergo episodic acidification during storms. Both streams showed decreases in pH to less than 5.0 standard units during stormflow. The acid-neutralizing capacity (ANC) of both streams decreased during stormflow, and the ANC of one of the streams, Bear Branch, became negative. The chemistries of the different types of waters that were sampled indicate that shallow subsurface water with minimal residence time in the watersheds is routed to the streams to become stormflow and is the cause of the episodic acidification observed. Three-component hydrograph separations were performed on the data collected during several storms in each watershed. The hydrograph separations of all of the storms indicate that throughfall contributed 0 to 50 percent of the stormflow, soil water contributed 0 to 80 percent, and ground water contributed 20 to 90 percent. The results of the hydrograph separations indicate that, in general, the watershed with higher hydraulic gradients tends to have shallower and shorter flow paths than the watershed with lower hydraulic gradients.

Maryland↗
USGS1997

Nitrogen and phosphorus loading from drained wetlands adjacent to Upper Klamath and Agency lakes, Oregon

Upper Klamath Lake and the connecting Agency Lake constitute a large, shallow lake in south-central Oregon that the historical record indicates has likely been eutrophic since its discovery by non-Native Americans. In recent decades, however, the lake has had annual occurrences of near-monoculture blooms of the blue-green alga Aphanizomenon flos-aquae that are thought to be a result of accelerated eutrophication. In 1988, two sucker species endemic to the lake, the Lost River sucker ( Deltistes luxatus ) and the shortnose sucker ( Chasmistes brevirostris ), were listed as endangered by the U.S. Fish and Wildlife Service, and it has been proposed that their decline is due to the poor water quality associated with extremely long and productive algal blooms. It has also been proposed that the effluent drained from wetlands has contributed to accelerated eutrophication. Since the turn of century, most of the wetlands adjacent to Upper Klamath Lake have been drained for agriculture--cultivation of crops and grazing of cattle. Wetland areas were reclaimed from the lake by building dikes to isolate them from the lake, constructing a series of drainage ditches, and installing pumps to drain the water and maintain a lowered water table. A consequence of lowering the water table is the increased ability of air and oxygenated water to move through the subsurface and facilitate the rapid aerobic decomposition of the peat soils. Nutrients, nitrogen and phosphorus, are then liberated, leach into adjacent ditches, and are subsequently pumped to the lake or its tributaries. The rate of peat decomposition may be related to the time since drainage and the type of agricultural land use. On lands cultivated for crops, farming practices, such as disking and furrowing, could enhance the movement of air and oxygenated water, resulting in a rapid rate of decomposition. In contrast, on grazed lands, the compaction of soils by cattle probably inhibits the movement of air and oxygenated water and results in a slower rate of decomposition relative to drained wetlands used for the cultivation of crops. This report presents the results of a cooperative study between the U.S. Geological Survey and the Bureau of Reclamation whose overall objective was to determine the nutrient loading to Upper Klamath Lake from adjacent drained wetlands. Nutrient loading from drained wetlands was estimated using two independent techniques. The first method involved the measurement of the quantity and quality of water discharged by pumps draining the wetlands. The second method was used to estimate the initial (before drainage) and present-day nutrient mass of the organic soils within the drained wetlands and to calculate the change (or loss) in nutrient mass. In an effort to estimate the nutrient contributions from the water pumped off selected drained wetlands adjacent to Upper Klamath Lake, annual loads and yields of total nitrogen and total phosphorus were estimated from concentration data and the volume of water pumped during the water year. In general, there was little variation among sites or among years in the annual total nitrogen (median load of about 18 tons per year and median yield of about 8 pounds per acre per year) or the annual total phosphorus (median load of about 3 tons per year and median yield of about 2 pounds per acre per year) contributions. The sum of the annual loads of nitrogen and phosphorus calculated for each of the pumping stations in 1995 was 80 tons per year and 15 tons per year, respectively. In 1995, soil-coring activities were undertaken to ascertain the nature and extent of the organic soils in the drained and undrained wetlands. The present-day nutrient mass was calculated for each drained wetland using the nutrient content (concentration) and the present-day peat mass. The initial nutrient mass prior to drainage was estimated for each drained wetland by using the initial nutrient content (assumed to be equal to the nutrient content of the undrained wetlands) and the initial peat mass as determined using the amount of accumulated decomposition residue. The cumulative loss of nutrient mass since drainage was calculated as the change between initial and present-day nutrient mass for each drained area. The cumulative yield of total nitrogen and total phosphorus loss from the organic soils of individual wetlands since drainage ranged from 3,000 to 70,000 pounds per acre and from 0 to 1,300 pounds per acre, respectively. For all the drained wetlands sampled, the cumulative nitrogen and phosphorus loss since drainage totaled 250,000 tons and 4,300 tons, respectively. This represents about 30 percent and 22 percent of the mass of nitrogen and phosphorus, respectively, that initially existed in the organic soils. The loss of nutrients from the drained wetlands is considered to be a maximum estimate of the possible contribution of nutrients to Upper Klamath Lake from the peat soils of the drained wetlands sampled. However, not all the nutrients released by the soils are discharged to the lake. Nutrients lost from the peat soils of the drained wetlands may have been taken up by crops and harvested or consumed by grazing cattle. In addition, nitrogen can be lost to the atmosphere by denitrification and the volatilization of ammonia; phosphorus may be bound to adjacent soil layers by adsorption. The annual nutrient loss for the period 1994–95 was calculated using a first-order rate law to describe nutrient loss since drainage began. For individual drained wetlands, the yield of nitrogen and phosphorus lost from the organic soils for the period 1994–95 ranged from 27 to 540 pounds per acre per year and from 0 to 15 pounds per acre per year, respectively. The total mass of nitrogen and phosphorus loss during this period was 3,000 tons per year and 60 tons per year, respectively, for all drained wetlands that were sampled. The yield and mass of nutrient loss determined in this fashion reflect what might be expected on the basis of time-averaged or longterm contributions of nutrients to the lake and do not reflect the specific conditions existing during the period 1994–95. The results of this study could be useful in helping to prioritize which drained wetlands may provide the greatest benefits with regard to reducing nutrient loads to the lake if restoration or land-use modifications are instituted. Recent acquisition and planned restoration of drained wetland areas at the Wood River and Williamson River North properties may produce significant reduction in the quantity of nutrients released by the decomposition of peat soils of these areas. If the water table rises to predrainage levels, the peats soils may become inundated most of the year, resulting in the continued long-term storage of nutrients within the peat soils by reducing aerobic decomposition. The maximum benefit, in terms of decreasing potential nutrient loss due to peat decomposition, could be the reduction of total nitrogen and total phosphorus loss to about one-half that of the 1994–95 annual loss estimated for all the drained wetlands sampled for this study.

Oregon↗
USGS1983

ROLES OF REMOTE SENSING AND CARTOGRAPHY IN THE USGS NATIONAL MAPPING DIVISION.

The inseparable roles of remote sensing and photogrammetry have been recognized to be consistent with the aims and interests of the American Society of Photogrammetry. In particular, spatial data storage, data merging and manipulation methods and other techniques originally developed for remote sensing applications also have applications for digital cartography. Also, with the introduction of much improved digital processing techniques, even relatively low resolution (80 m) traditional Landsat images can now be digitally mosaicked into excellent quality 1:250,000-scale image maps.

Conference Paper↗