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At least 1,171 records · Page 65Linked to original sources

USGS2018

Groundwater discharge characteristics for selected streams within the Loup River Basin, Nebraska, 2014–16

Streams in the Loup River Basin are sensitive to groundwater withdrawals because of the close hydrologic connection between groundwater and surface water. Groundwater discharge is the primary component of streamflow in the Loup River Basin and constitutes more than 90 percent of streamflow in the central part of the Sand Hills. To improve the understanding of geologic controls and various climatic and land-use changes on groundwater discharge, the U.S. Geological Survey (USGS), in cooperation with the Upper Loup Natural Resources District (NRD), the Lower Loup NRD, and the Nebraska Environmental Trust, studied the spatial and temporal characteristics of groundwater discharge within the Loup River Basin. This report documents the methods of data collection and analysis, which include the collection of approximately 350 river miles of aerial thermal infrared imagery and continuous groundwater-level and temperature data from six streamflow-gaging stations within the Loup River Basin. The results from the stream reconnaissance and examination of aerial thermal infrared imagery demonstrated the influence of the surficial and subsurface geology on the spatial characteristics of groundwater discharge to streams in the Loup River Basin. At the headwaters of the South Loup River, streamflow is sustained and increased from focused groundwater discharge emanating from Quaternary deposits at many small (less than 0.1 cubic foot per second) focused points. The volume of water produced from this dense network of focused groundwater discharge points along the North Fork South Loup River is sufficient to provide approximately 40 percent of the flow measured at the South Loup River at Arnold, Nebraska streamflow-gaging station (USGS station 06781600) during the irrigation season. Approximately 5 miles downstream from the South Loup River at Arnold, Nebr., streamflow-gaging station, the river incises into Pliocene-age sand and gravel deposits, which provide additional groundwater discharge to the stream. The streamflow of the South Loup River increases by a factor of 5 across a 62-mile reach of the middle South Loup River. Increases in streamflow along the upper Dismal River result from a dense network of focused groundwater discharge points within semiconsolidated Pliocene-age deposits. Below the Dismal River near Thedford, Nebr., streamflow-gaging station (USGS station 06775900), the Dismal River incises into the Ogallala Formation over a short reach before flowing over coarser, more permeable Quaternary-age alluvial deposits. Diffuse groundwater discharge sustains and increases the streamflow of the lower Dismal River in this reach. Groundwater sapping was evident on some stream reaches and has increased the size and flow of focused groundwater discharge points. Previous researchers have documented streambed incision and groundwater sapping on the upper Dismal River that have created and enlarged focused groundwater discharge points capturing additional groundwater. Similar processes appear to have played a role in the formation of larger focused groundwater discharge points, which sustain the flow of the middle South Loup River. The constant flow of groundwater into the South Loup River has removed finer-grained Quaternary sediments and further exposed Pliocene-age gravel deposits. Headward erosion is evident where some of the large focused groundwater discharge points have incised their own draws and terminate in bowl-like depressions away from the stream. Within the Loup River NRDs, the percentage of groundwater-irrigated land in a stream basin is one factor that affects groundwater discharge to streams. A striking example was at the South Loup River at Saint Michael, Nebr., groundwater and streamflow-gaging station (USGS station 06784000) where the shallow groundwater levels declined below the level of the stream during the middle to late part of the growing season (July to September) when consumptive groundwater use was at its peak. The South Loup River Basin above the South Loup River at Saint Michael, Nebr., streamflow-gaging station has the highest percentage of groundwater-irrigated row crops of all the basins examined in this study. Continuous groundwater and surface-water levels measured at the North Loup River at the Taylor, Nebr., streamflow-gaging station (USGS station 06786000) indicate that the stream is receiving groundwater throughout the year; however, when consumptive groundwater use peaks during the middle to late part of the growing season (July to September), the difference in elevation between the groundwater level and the stream elevation decreases, which indicates a reduction in the amount of groundwater discharge received.

Nebraska↗

USGS1976

Submarine geothermal resources

Approximately 20% of the earth's heat loss (or 2 ?? 1012 cal/s) is released through 1% of the earth's surface area and takes the form of hydrothermal discharge from young (Pleistocene or younger) rocks adjacent to active seafloor-spreading centers and submarine volcanic areas. This amount is roughly equivalent to man's present gross energy consumption rate. A sub-seafloor geothermal reservoir, to be exploitable under future economic conditions, will have to be hot, porous, permeable, large, shallow, and near an energy-deficient, populated land mass. Furthermore, the energy must be recoverable using technology achievable at a competitive cost and numerous environmental, legal and institutional problems will have to be overcome. The highest-temperature reservoirs should be found adjacent to the zones of the seafloor extension or volcanism that are subject to high sedimentation rates. The relatively impermeable sediments reduce hydrothermal-discharge flow rates, forcing the heat to be either conducted away or released by high-temperature fluids, both of which lead to reservoir temperatures that can exceed 300??C. There is evidence that the oceanic crust is quite permeable and porous and that it was amenable to deep (3-5 km) penetration by seawater at least some time in the early stages of its evolution. Most of the heat escapes far from land, but there are notable exceptions. For example, in parts of the Gulf of California, thermal gradients in the bottom sediments exceed 1??C/m. In the coastal areas of the Gulf of California, where electricity and fresh water are at a premium, this potential resource lies in shallow water (< 200 m) and within sight of land. Other interesting areas include the Sea of Japan, the Sea of Okhotsk and the Andaman Sea along the margins of the western Pacific, the Tyrrhenian Sea west of Italy, and the southern California borderland and west flank of the Juan de Fuca Ridge off the west coast of the United States. Many questions remain to be answered about the physical and other characteristics of these systems before they can be considered a viable resource. Until several of the most promising areas are carefully defined and drilled, the problem will remain unresolved. ?? 1976.

Journal of Volcanology and Geothermal Research↗

USGS2023

Diverse portfolios: Investing in tributaries for restoration of large river fishes in the Anthropocene

Rehabilitation of large Anthropocene rivers requires engagement of diverse stakeholders across a broad range of sociopolitical boundaries. Competing objectives often constrain options for ecological restoration of large rivers whereas fewer competing objectives may exist in a subset of tributaries. Further, tributaries contribute toward building a “portfolio” of river ecosystem assets through physical and biological processes that may present opportunities to enhance the resilience of large river fishes. Our goal is to review roles of tributaries in enhancing mainstem large river fish populations. We present case histories from two greatly altered and distinct large-river tributary systems that highlight how tributaries contribute four portfolio assets to support large-river fish populations: 1) habitat diversity, 2) connectivity, 3) ecological asynchrony, and 4) density-dependent processes. Finally, we identify future research directions to advance our understanding of tributary roles and inform conservation actions. In the Missouri River United States, we focus on conservation efforts for the state endangered lake sturgeon, which inhabits large rivers and tributaries in the Midwest and Eastern United States. In the Colorado River, Grand Canyon United States, we focus on conservation efforts for recovery of the federally threatened humpback chub. In the Missouri River, habitat diversity focused on physical habitats such as substrate for reproduction, and deep-water habitats for refuge, whereas augmenting habitat diversity for Colorado River fishes focused on managing populations in tributaries with minimally impaired thermal and flow regimes. Connectivity enhancements in the Missouri River focused on increasing habitat accessibility that may require removal of physical structures like low-head dams; whereas in the Colorado River, the lack of connectivity may benefit native fishes as the disconnection provides refuge from non-native fish predation. Hydrologic variability among tributaries was present in both systems, likely underscoring ecological asynchrony. These case studies also described density dependent processes that could influence success of restoration actions. Although actions to restore populations varied by river system, these examples show that these four portfolio assets can help guide restoration activities across a diverse range of mainstem rivers and their tributaries. Using these assets as a guide, we suggest these can be transferable to other large river-tributary systems.

Frontiers in Environmental Science↗

USGS2008

Co-precipitation of dissolved organic matter by calcium carbonate in Pyramid Lake, Nevada

Our previous research has demonstrated that dissolved organic matter (DOM) influences calcium carbonate mineral formation in surface and ground water. To better understand DOM mediation of carbonate precipitation and DOM co-precipitation and/or incorporation with carbonate minerals, we characterized the content and speciation of DOM in carbonate minerals and in the lake water of Pyramid Lake, Nevada, USA. A 400-gram block of precipitated calcium carbonate from the Pyramid Lake shore was dissolved in 8 liters of 10% acetic acid. Particulate matter not dissolved by acetic acid was removed by centrifugation. DOM from the carbonate rock was fractionated into nine portions using evaporation, dialysis, resin adsorption, and selective precipitations to remove acetic acid and inorganic constituents. The calcium carbonate rock contained 0.23% DOM by weight. This DOM was enriched in polycarboxylic proteinaceous acids and hydroxy-acids in comparison with the present lake water. DOM in lake water was composed of aliphatic, alicyclic polycarboxylic acids. These compound classes were found in previous studies to inhibit calcium carbonate precipitation. DOM fractions from the carbonate rock were 14 C-age dated at about 3,100 to 3,500 years before present. The mechanism of DOM co-precipitation and/or physical incorporation in the calcium carbonate is believed to be due to formation of insoluble calcium complexes with polycarboxylic proteinaceous acids and hydroxy-acids that have moderately large stability constants at the alkaline pH of the lake. DOM co-precipitation with calcium carbonate and incorporation in precipitated carbonate minerals removes proteinaceous DOM, but nearly equivalent concentrations of neutral and acidic forms of organic nitrogen in DOM remain in solution. Calcium carbonate precipitation during lime softening pretreatment of drinking water may have practical applications for removal of proteinaceous disinfection by-product precursors.

Nevada↗

USGS2016

Groundwater science relevant to the Great Lakes Water Quality Agreement: A status report

When the Great Lakes Water Quality Agreement (GLWQA) was signed in 1972 by the Governments of Canada and the United States (the “Parties”) (Environment Canada, 2013a), groundwater was not recognized as important to the water quality of the Lakes. At that time, groundwater and surface water were still considered as two separate systems, with almost no appreciation for their interaction. When the GLWQA was revised in 1978 (US Environmental Protection Agency (USEPA), 2012), groundwater contamination, such as that reported at legacy industrial sites such as those at Love Canal near the Niagara River, was squarely in the news. Consequently, the potential impacts of contaminated groundwater from such sites on Great Lakes water quality became a concern (Beck, 1979), and Annex 16 was added to the agreement, to address “pollution from contaminated groundwater” (Francis, 1989). However, no formal process for reporting under this annex was provided. The GLWQA Protocol in 1987 modified Annex 16 and called for progress reports beginning in 1988 (USEPA, 1988). The Protocol in 2012 provided a new Annex 8 to address groundwater more holistically (Environment 2 Canada, 2013b). Annex 8 (Environment Canada, 2013b) commits the Parties to coordinate groundwater science and management actions; as a first step, to “publish a report on the relevant and available groundwater science” by February 2015 (this report); and to “identify priorities for science activities and actions for groundwater management, protection, and remediation…” The broader mandate of Annex 8 is to (1) “identify groundwater impacts on the chemical, physical and biological integrity of the Waters of the Great Lakes;” (2) “analyze contaminants, including nutrients in groundwater, derived from both point and non-point sources impacting the Waters of the Great Lakes;” (3) “assess information gaps and science needs related to groundwater to protect the quality of the Waters of the Great Lakes;” and (4) “analyze other factors, such as climate change, that individually or cumulatively affect groundwater’s impact on the quality of the Waters of the Great Lakes.” A binational Annex 8 Subcommittee was formed to lead efforts to fulfill the mandate of this annex (members listed on p. i of this report). In turn, this subcommittee has recruited a task team to prepare this report (listed as authors of each chapter). This report addresses all of the above four objectives, based on a compilation of the “relevant and available groundwater science.” Specifically, the second objective (to “analyze contaminants”) is addressed by incorporating information obtained in ongoing monitoring and research activities conducted by the Parties, and by various other members of the Great Lakes Executive Committee.

Illinois, Indiana, Michigan, Minnesota, New York, ↗

USGS2013

Comparison of water consumption in two riparian vegetation communities along the central Platte River, Nebraska, 2008–09 and 2011

The Platte River is a vital natural resource for the people, plants, and animals of Nebraska. A recent study quantified water use by riparian woodlands along central reaches of the Platte River, Nebraska, finding that water use was mainly regulated below maximum predicted levels. A comparative study was launched through a cooperative partnership between the U.S. Geological Survey, the Central Platte Natural Resources District, the Nebraska Department of Natural Resources, and the Nebraska Environmental Trust to compare water use of a riparian woodland with that of a grazed riparian grassland along the central Platte River. This report describes the results of the 3-year study by the U.S. Geological Survey to measure the evapotranspiration (ET) rates in the two riparian vegetation communities. Evapotranspiration was measured during 2008–09 and 2011 using the eddy-covariance method at a riparian woodland near Odessa, hereinafter referred to as the “woodland site,” and a riparian grassland pasture near Elm Creek, hereinafter referred to as the “grassland site.” Overall, annual ET totals at the grassland site were 90 percent of the annual ET measured at the woodland site, with averages of 653 millimeters (mm) and 726 mm, respectively. Evapotranspiration rates were similar at the grassland site and the woodland site during the spring and fall seasons, but at the woodland site ET rates were higher than those of the grassland site during the peak-growth summer months of June through August. These seasonal differences and the slightly lower ET rates at the grassland site were likely the result of differing plant communities, disturbance effects related to grazing and flooding, and climatic differences between the sites. The annual water balance was calculated for each site and indicated that the predominant factors in the water balance at both sites were ET and precipitation. Annual precipitation for the study period ranged from near to above the normal precipitation of 640 mm. Substantial precipitation fell in May and October 2008 that caused flooding along the Platte River in May of this especially wet year. There was a deficit in precipitation compared to ET at both sites in 2009 and 2011, leading to a net groundwater use of greater than 140 mm per year at the woodland site and greater than 55 mm per year at the grassland site. This indicates that the net annual groundwater use or recharge depends predominately upon the relation between ET and precipitation in these riparian areas with shallow soil layers above the groundwater table. Prior research at the woodland site provided four additional annual water balances dating back to 2002 for comparison with the study period at the woodland site. Perhaps most striking in this comparison was the 25-percent increase in annual ET for 2008–09 and 2011 despite precipitation totals and potential ET rates that were within the range of those measured in 2002–05. As a result, the water balance indicates that groundwater was discharged 2 of the 3 years of the study. This likely was caused by higher groundwater levels and a healthier plant community in 2008–09 and 2011 relative to the drought-affected years of 2002–05. As a result of these changes, the crop coefficients developed for riparian woodlands during the prior research underestimated 2008–09 and 2011 annual ET rates by an average of 35 percent. Though new crop coefficients were developed by this study, the importance of soil-moisture stress and plant community successional dynamics need to be considered when applying these coefficients at other riparian sites or into the future. Nonetheless, their development and the data on which they are based may provide improved understanding of water consumption by riparian grasslands and riparian woodlands along the central Platte River.

Nebraska↗

USGS2015

Concentrations and distributions of metals associated with dissolved organic matter from the Suwannee River (GA, USA)

Concentrations and distributions of metals in Suwannee River (SR) raw filtered surface water (RFSW) and dissolved organic matter (DOM) processed by reverse osmosis (RO), XAD-8 resin (for humic and fulvic acids [FA]), and XAD-4 resin (for “transphilic” acids) were analyzed by asymmetrical flow field-flow fractionation (AsFlFFF). SR samples were compared with DOM samples from Nelson's Creek (NLC), a wetland-draining stream in northern Michigan; previous International Humic Substances Society (IHSS) FA and RO samples from the SR; and an XAD-8 sample from Lake Fryxell (LF), Antarctica. Despite application of cation exchange during sample processing, all XAD and RO samples contained substantial metal concentrations. AsFlFFF fractograms allowed metal distributions to be characterized as a function of DOM component molecular weight (MW). In SR RFSW, Fe, Al, and Cu were primarily associated with intermediate to higher than average MW DOM components. SR RO, XAD-8, and XAD-4 samples from May 2012 showed similar MW trends for Fe and Al but Cu tended to associate more with lower MW DOM. LF DOM had abundant Cu and Zn, perhaps due to amine groups that should be present due to its primarily algal origins. None of the fractograms showed obvious evidence for mineral nanoparticles, although some very small mineral nanoparticles might have been present at trace concentrations. This research suggests that AsFlFFF is important for understanding how metals are distributed in different DOM samples (including IHSS samples), which may be key to metal reactivity and bioavailability.

Georgia↗

USGS2003

Athena Mars rover science investigation

Each Mars Exploration Rover carries an integrated suite of scientific instruments and tools called the Athena science payload. The primary objective of the Athena science investigation is to explore two sites on the Martian surface where water may once have been present, and to assess past environmental conditions at those sites and their suitability for life. The remote sensing portion of the payload uses a mast called the Pancam Mast Assembly (PMA) that provides pointing for two instruments: the Panoramic Camera (Pancam), and the Miniature Thermal Emission Spectrometer (Mini-TES). Pancam provides high-resolution, color, stereo imaging, while Mini-TES provides spectral cubes at mid-infrared wavelengths. For in-situ study, a five degree-of-freedom arm called the Instrument Deployment Device (IDD) carries four more tools: a Microscopic Imager (MI) for close-up imaging, an Alpha Particle X-Ray Spectrometer (APXS) for elemental chemistry, a Mo??ssbauer Spectrometer (MB) for the mineralogy of Fe-bearing materials, and a Rock Abrasion Tool (RAT) for removing dusty and weathered surfaces and exposing fresh rock underneath. The payload also includes magnets that allow the instruments to study the composition of magnetic Martian materials. All of the Athena instruments have undergone extensive calibration, both individually and using a set of geologic reference materials that are being measured with all the instruments. Using a MER-like rover and payload in a number of field settings, we have devised operations processes that will enable us to use the MER rovers to formulate and test scientific hypotheses concerning past environmental conditions and habitability at the landing sites. Copyright 2003 by the American Geophysical Union.

Journal of Geophysical Research E: Planets↗

USGS2009

The ecological limits of hydrologic alteration (ELOHA): A new framework for developing regional environmental flow standards

The flow regime is a primary determinant of the structure and function of aquatic and riparian ecosystems for streams and rivers. Hydrologic alteration has impaired riverine ecosystems on a global scale, and the pace and intensity of human development greatly exceeds the ability of scientists to assess the effects on a river-by-river basis. Current scientific understanding of hydrologic controls on riverine ecosystems and experience gained from individual river studies support development of environmental flow standards at the regional scale. 2. This paper presents a consensus view from a group of international scientists on a new framework for assessing environmental flow needs for many streams and rivers simultaneously to foster development and implementation of environmental flow standards at the regional scale. This framework, the ecological limits of hydrologic alteration (ELOHA), is a synthesis of a number of existing hydrologic techniques and environmental flow methods that are currently being used to various degrees and that can support comprehensive regional flow management. The flexible approach allows scientists, water-resource managers and stakeholders to analyse and synthesise available scientific information into ecologically based and socially acceptable goals and standards for management of environmental flows. 3. The ELOHA framework includes the synthesis of existing hydrologic and ecological databases from many rivers within a user-defined region to develop scientifically defensible and empirically testable relationships between flow alteration and ecological responses. These relationships serve as the basis for the societally driven process of developing regional flow standards. This is to be achieved by first using hydrologic modelling to build a 'hydrologic foundation' of baseline and current hydrographs for stream and river segments throughout the region. Second, using a set of ecologically relevant flow variables, river segments within the region are classified into a few distinctive flow regime types that are expected to have different ecological characteristics. These river types can be further subclassified according to important geomorphic features that define hydraulic habitat features. Third, the deviation of current-condition flows from baseline-condition flow is determined. Fourth, flow alteration-ecological response relationships are developed for each river type, based on a combination of existing hydroecological literature, expert knowledge and field studies across gradients of hydrologic alteration. 4. Scientific uncertainty will exist in the flow alteration-ecological response relationships, in part because of the confounding of hydrologic alteration with other important environmental determinants of river ecosystem condition (e.g. temperature). Application of the ELOHA framework should therefore occur in a consensus context where stakeholders and decision-makers explicitly evaluate acceptable risk as a balance between the perceived value of the ecological goals, the economic costs involved and the scientific uncertainties in functional relationships between ecological responses and flow alteration. 5. The ELOHA framework also should proceed in an adaptive management context, where collection of monitoring data or targeted field sampling data allows for testing of the proposed flow alteration-ecological response relationships. This empirical validation process allows for a fine-tuning of environmental flow management targets. The ELOHA framework can be used both to guide basic research in hydroecology and to further implementation of more comprehensive environmental flow management of freshwater sustainability on a global scale. ?? 2009 Blackwell Publishing Ltd.

Freshwater Biology↗

USGS2017

Monitoring gas and heat emissions at Norris Geyser Basin, Yellowstone National Park, USA based on a combined eddy covariance and Multi-GAS approach

We quantified gas and heat emissions in an acid-sulfate, vapor-dominated area (0.04-km 2 ) of Norris Geyser Basin, located just north of the 0.63 Ma Yellowstone Caldera and near an area of anomalous uplift. From 14 May to 3 October 2016, an eddy covariance system measured half-hourly CO 2 , H 2 O and sensible ( H ) and latent ( LE ) heat fluxes and a Multi-GAS instrument measured (1 Hz frequency) atmospheric H 2 O, CO 2 and H 2 S volumetric mixing ratios. We also measured soil CO 2 fluxes using the accumulation chamber method and temperature profiles on a grid and collected fumarole gas samples for geochemical analysis. Eddy covariance CO 2 fluxes ranged from − 56 to 885 g m − 2 d − 1 . Using wavelet analysis, average daily eddy covariance CO 2 fluxes were locally correlated with average daily environmental parameters on several-day to monthly time scales. Estimates of CO 2 emission rate from the study area ranged from 8.6 t d − 1 based on eddy covariance measurements to 9.8 t d − 1 based on accumulation chamber measurements. Eddy covariance water vapor fluxes ranged from 1178 to 24,600 g m − 2 d − 1 . Nighttime H and LE were considered representative of hydrothermal heat fluxes and ranged from 4 to 183 and 38 to 504 W m − 2 , respectively. The total hydrothermal heat emission rate ( H + LE + radiant) estimated for the study area was 11.6 MW and LE contributed 69% of the output. The mean ± standard deviation of H 2 O, CO 2 and H 2 S mixing ratios measured by the Multi-GAS system were 9.3 ± 3.1 parts per thousand, 467 ± 61 ppmv, and 0.5 ± 0.6 ppmv, respectively, and variations in the gas compositions were strongly correlated with diurnal variations in environmental parameters (wind speed and direction, atmospheric temperature). After removing ambient H 2 O and CO 2 , the observed variations in the Multi-GAS data could be explained by the mixing of relatively H 2 O-CO 2 -H 2 S-rich fumarole gases with CO 2 -rich and H 2 O-H 2 S-poor soil gases. The fumarole H 2 O/CO 2 and CO 2 /H 2 S end member ratios (101.7 and 27.1, respectively, on average) were invariant during the measurement period and fell within the range of values measured in direct fumarole gas samples. The soil gas H 2 O/CO 2 end member ratios (~ 15–30) were variable and low relative to the fumarole end member, likely resulting from water vapor loss during cooling and condensation in the shallow subsurface, whereas the CO 2 /H 2 S end member ratio was high (~ 160), presumably related to transport of CO 2 -dominated soil gas emissions mixed with trace fumarolic emissions to the Multi-GAS station. Nighttime eddy covariance ratios of H 2 O to CO 2 flux were typically between the soil gas and fumarole end member H 2 O/CO 2 ratios defined by Multi-GAS measurements. Overall, the combined eddy covariance and Multi-GAS approach provides a powerful tool for quasi-continuous measurements of gas and heat emissions for improved volcano-hydrothermal monitoring.

Wyoming↗

USGS2016

Proceedings of the 12th Biennial Conference of research on the Colorado Plateau

Introduction The Colorado Plateau is a physiographic region that encompasses 330,000 square kilometers in parts of four states in the southwestern United States (Colorado, Utah, New Mexico, and Arizona). Known for its high deserts, the Colorado Plateau also includes isolated mountains, high plateaus, and rugged canyons. Not only is the region topographically diverse, but geologically, biologically, and culturally diverse as well. The landscape is managed by Federal entities including the Bureau of Land Management, the National Park Service, and the U.S. Forest Service; Tribal nations including the Navajo Nation, Kaibab Paiute, Mountain Ute, Southern Ute, Hopi, Zuni, Hualapai, Havasupai, and White Mountain Apache Tribes; State land and wildlife management agencies; and privately owned holdings, creating complex interactions and management challenges. Population growth, increased tourism to Federal and State lands, and energy development have increased water demands and altered land-use patterns, and these changes have emerged as management challenges facing the people working and living in the region. Climate change, particularly the ongoing drought, has exacerbated the effects of population growth, land-use change, and other stressors such as invasive species. As managers seek solutions to the challenges facing the region’s natural and cultural resources, the Biennial Conference of Science and Management of the Colorado Plateau has become an important venue for exchanging information about emerging management concerns and recent scientific research. Each biennial conference has sought to promote discussion, information sharing, and productive communication among the managers, scientists, students, administrators, tribal representatives, and others who attend the conference with the goal of enhancing the use of the best available science to manage the region’s incomparable natural and cultural resources. The publication and dissemination of a conference proceedings series expands the reach of the conference beyond those people in attendance and creates a record on the research presented. The idea of producing a conference proceedings, and its subsequent publication, first occurred in 1993 following the first biennial conference in 1991. A published volume of contributed papers has followed each subsequent biennial conference, including this volume. The venue for publishing proceedings has changed over the years and has included the National Park Service, the Government Printing Office, the U.S. Geological Survey, and University of Arizona Press. Recently, van Riper and others (2015) published a compilation of the abstracts from the 11 previous conference proceedings. Collectively, the proceedings highlight approximately 25 years of natural- and cultural-resources research, promoting the integration of research with resource management across the Colorado Plateau. This volume is freely downloadable by the public, thereby further expanding the influence of this conference beyond the Colorado Plateau. The 12th Biennial Conference held in Flagstaff, Arizona, from September 16 to 19, 2013, covered a range of topics in the physical, biological, and socio-cultural sciences. The conference was organized and hosted by Northern Arizona University’s ( NAU) Merriam-Powell Center for Environmental Research, the Colorado Plateau Cooperative Ecosystem Studies Unit, and the U.S. Geological Survey Southwest Biological Science Center. Financial and in-kind support was provided by a wide range of organizations including the U.S. Forest Service, National Park Service, Bureau of Land Management, Grand Canyon Trust, Colorado Plateau Research Station, and various NAU entities. NAU sponsors include the Landscape Conservation Initiative, School of Forestry, School of Earth Science and Environmental Sustainability, Office of the Provost, and Office of the Vice President of Research. Contributors to these proceedings include researchers and managers from Federal, State, and Tribal governments, universities, private entities, and non-profit organizations. In this regard, this conference has wide-ranging support and participation among private and public entities involved in the science and management of natural resources on the Colorado Plateau.

Arizona, Colorado, New Mexico, Utah↗

USGS2012

Modeling tidal exchange and dispersion in Boston Harbor

Tidal dispersion and the horizontal exchange of water between Boston Harbor and the surrounding ocean are examined with a high-resolution (200 m) depth-averaged numerical model. The strongly varying bathymetry and coastline geometry of the harbor generate complex spatial patterns in the modeled tidal currents which are verified by shipboard acoustic Doppler surveys. Lagrangian exchange experiments demonstrate that tidal currents rapidly exchange and mix material near the inlets of the harbor due to asymmetry in the ebb/flood response. This tidal mixing zone extends roughly a tidal excursion from the inlets and plays an important role in the overall flushing of the harbor. Because the tides can only efficiently mix material in this limited region, however, harbor flushing must be considered a two step process: rapid exchange in the tidal mixing zone, followed by flushing of the tidal mixing zone by nontidal residual currents. Estimates of embayment flushing based on tidal calculations alone therefore can significantly overestimate the flushing time that would be expected under typical environmental conditions. Particle-release simulations from point sources also demonstrate that while the tides efficiently exchange material in the vicinity of the inlets, the exact nature of dispersion from point sources is extremely sensitive to the timing and location of the release, and the distribution of particles is streaky and patchlike. This suggests that high-resolution modeling of dispersion from point sources in these regions must be performed explicitly and cannot be parameterized as a plume with Gaussian-spreading in a larger scale flow field.

Massachusetts↗

USGS2010

Inferring shallow groundwater flow in saprolite and fractured rock using environmental tracers

The Ridge and Valley Province of eastern Tennessee is characterized by (1) substantial topographic relief, (2) folded and highly fractured rocks of various lithologies that have low primary permeability and porosity, and (3) a shallow residuum of medium permeability and high total porosity. Conceptual models of shallow groundwater flow and solute transport in this system have been developed but are difficult to evaluate using physical characterization or short‐term tracer methods due to extreme spatial variability in hydraulic properties. In this paper we describe how chlorofluorocarbon 12, 3 H, and 3 He were used to infer groundwater flow and solute transport in saprolite and fractured rock near Oak Ridge, Tennessee. In the shallow residuum, fracture spacings are <0.05 m, suggesting that concentrations of these tracers in fractures and in the matrix have time to diffusionally equilibrate. The relatively smooth nature of tracer concentrations with depth in the residuum is consistent with this model and quantitatively suggests recharge fluxes of 0.2 to 0.4 m yr −1 . In contrast, groundwater flow within the unweathered rock appears to be controlled by fractures with spacings of the order of 2 to 5 m, and diffusional equilibration of fractures and matrix has not occurred. For this reason, vertical fluid fluxes in the unweathered rock cannot be estimated from the tracer data.

Water Resources Research↗

USGS2015

Predicting the resilience and recovery of aquatic systems: a framework for model evolution within environmental observatories

Maintaining the health of aquatic systems is an essential component of sustainable catchmentmanagement, however, degradation of water quality and aquatic habitat continues to challenge scientistsand policy-makers. To support management and restoration efforts aquatic system models are requiredthat are able to capture the often complex trajectories that these systems display in response to multiplestressors. This paper explores the abilities and limitations of current model approaches in meeting this chal-lenge, and outlines a strategy based on integration of ﬂexible model libraries and data from observationnetworks, within a learning framework, as a means to improve the accuracy and scope of model predictions.The framework is comprised of a data assimilation component that utilizes diverse data streams from sensornetworks, and a second component whereby model structural evolution can occur once the model isassessed against theoretically relevant metrics of system function. Given the scale and transdisciplinarynature of the prediction challenge, network science initiatives are identiﬁed as a means to develop and inte-grate diverse model libraries and workﬂows, and to obtain consensus on diagnostic approaches to modelassessment that can guide model adaptation. We outline how such a framework can help us explore thetheory of how aquatic systems respond to change by bridging bottom-up and top-down lines of enquiry,and, in doing so, also advance the role of prediction in aquatic ecosystem management.

Water Resources Research↗

USGS2022

Multi-factor biotopes as a method for detailed site characterization in diverse benthic megafaunal communities and habitats in deep-water off Morro Bay, California

Here we describe the methods and results for biological characterization of the benthos on a previously unexplored area of central California, USA seafloor. We conducted 40 remotely operated vehicle dives from 371 to 1173 m water depth. Seafloor habitats and megafauna (fish and invertebrates) were documented from 46.8 km of seafloor video footage. Our expanded development and analysis of biotopes from quantitative data allowed us to describe detailed biological communities, along with the physical characteristics and habitat associations within the study area. This method provides a framework for potential monitoring, detection of future environmental change (natural and anthropogenic) and comprehensive comparison to other deep water regions. From 185 h of observational video at 25 sites, nearly 120,000 annotations of organisms, habitat characters, biological detritus and anthropogenic debris were recorded and analyzed. We identified a total of 228 taxa, with 173 of them present on linear quantitative transects. Species richness for transects ranged from 0.04 to 0.28 m-2 (8–55 taxa), with densities ranging from 0.07 to 5.20 ind. m−2. Both were highest on hard substrate with greatest surface area. Densities decreased with depth. Within soft substratum zones was a large field of pockmarks, which are seafloor depressions averaging 175 m in diameter and 5 m in depth. Pockmarks have sometimes been associated with seafloor gas seepage, but here we found no biological evidence of chemosynthetic organisms. No significant differences were found in either density nor species richness at pockmark sites vs. non-pockmark sites. Mud draped greenish-black coarse sand occurred only in low oxygen areas, while hummocky, rugose mud supported somewhat different species than flat mud plains. Seventy percent of the transects occurred inside the oxygen minimum zone. We conclude that high rugosity, slope, and the presence of hard substratum were better predictors of species richness and density than oxygen concentration in this specific study. Abundant biological detritus, in the form of dead and dying pelagic pyrosomes and salps, created a large, presumably ephemeral flux of carbon to the seafloor during the study period.

California↗

USGS2007

Modeling the biophysical impacts of global change in mountain biosphere reserves

Mountains and mountain societies provide a wide range of goods and services to humanity, but they are particularly sensitive to the effects of global environmental change. Thus, the definition of appropriate management regimes that maintain the multiple functions of mountain regions in a time of greatly changing climatic, economic, and societal drivers constitutes a significant challenge. Management decisions must be based on a sound understanding of the future dynamics of these systems. The present article reviews the elements required for an integrated effort to project the impacts of global change on mountain regions, and recommends tools that can be used at 3 scientific levels (essential, improved, and optimum). The proposed strategy is evaluated with respect to UNESCO's network of Mountain Biosphere Reserves (MBRs), with the intention of implementing it in other mountain regions as well. First, methods for generating scenarios of key drivers of global change are reviewed, including land use/land cover and climate change. This is followed by a brief review of the models available for projecting the impacts of these scenarios on (1) cryospheric systems, (2) ecosystem structure and diversity, and (3) ecosystem functions such as carbon and water relations. Finally, the cross-cutting role of remote sensing techniques is evaluated with respect to both monitoring and modeling efforts. We conclude that a broad range of techniques is available for both scenario generation and impact assessments, many of which can be implemented without much capacity building across many or even most MBRs. However, to foster implementation of the proposed strategy, further efforts are required to establish partnerships between scientists and resource managers in mountain areas.

Mountain Research and Development↗

USGS2020

Aquatic invasive species in the Chesapeake Bay drainage—Research-based needs and priorities of U.S. Geological Survey partners and collaborators

Executive Summary The U.S. Geological Survey (USGS) is revising the Chesapeake Bay-based science plan to align it with recent U.S. Department of Interior and USGS science priorities that include, as stated in the plan, providing “an integrated understanding of the factors affecting fish habitat, fish health, and landscape conditions” in Chesapeake Bay and its watershed. A report of partner agencies’ needs and priorities related to aquatic invasive species (AIS) science was identified as an informational gap; a report would help to further development of the science program related to aquatic animal health and habitat. This objective was addressed through review of pertinent documentation and conversations with representatives of State, Federal, and regional agencies with vested interests in AIS management in Chesapeake Bay and the Chesapeake Bay drainage area, and this document was produced to summarize the related findings. All agencies and organizations (13) reported that AIS are of general concern, with most stakeholder groups reporting AIS-related issues to be of high priority, including invasive fishes and invertebrates, invasive plants, and microbes including aquatic animal pathogens. Invasive fishes are of great concern to all partner agencies. Channa argus (northern snakehead) and Ictalurus furcatus (blue catfish) are high priority and represent the two most named AIS of concern for these agencies. Nine of 10 stakeholder groups listed northern snakehead as a high priority species, and 6 listed blue catfish as a high priority species as well. Pylodictis olivaris (flathead catfish), invasive crayfish species , and dressenid mussels were also prioritized by multiple partner groups, each receiving specific mention by at least 3 of the 10 stakeholder groups in discussions or documents. Invasive carp, such as Hypophthalmichthys molatrix (silver carp), also received mention by multiple agencies (3 of the 10 stakeholder groups) because these fish represent priority AIS in nearby watersheds and a threat for introduction and dissemination within the Chesapeake Bay watershed from these neighboring regions. Invasive plants are among priority species, and Hydrilla verticillata (hydrilla) topped the list. Hydrilla was reported as a priority species by 5 of the stakeholder groups queried. Trapa natans and T. bispinosa (water chestnut), Phragmites australis (common reed), and Lythrum salicaria (purple loosestrife) were also among the aquatic invasive plants that were prioritized by multiple partner agencies. Multiple stakeholder groups (5 of the 10 groups) also considered Didymosphenia geminata (didymo) and various aquatic animal pathogens among their priority AIS for management considerations. Science needs that were recurrently indicated by stakeholders to support management of invasive species include Technology to enhance biosurveillance capability, such as reliable environmental DNA based detection methodology; Risk assessment modeling to forewarn of and prioritize AIS-related threats; Increased information and intervention methods related to vectors and pathways of AIS introductions; Increased information about the biology and life history of AIS, including information related to trophic interactions, health and disease, and distribution and abundance; and Potential applications of mitigation strategies, including genetically based biocontrol mechanisms. Potential next steps to address the science needs include Development of biosurveillance and risk assessment tools for identification of AIS in proactive management; Development of proactive management techniques to prevent AIS introductions through recognized vectors and pathways; Development of interagency biosurveillance programs to best utilize personnel, funds, and other resources among interested agencies and organizations; Investigations to address life history, consequences, and movement/dissemination of top priority invasive species in the region; Investigations to determine the potential for novel mitigation technologies, such as the application of synthetic biological (genetic) control methods; and Investigations with focus on emerging and high priority AIS in the region, including fishes (blue catfish, flathead catfish, northern snakehead), invertebrates (invasive crayfish and mollusks) and plants (hydrilla, water chestnut, phragmites).

Virginia, Maryland, Delaware, West Virginia, Penns↗

USGS2014

Use of dynamic occupancy models to assess the response of Darters (Teleostei: Percidae) to varying hydrothermal conditions in a southeastern United States tailwater

During the past 100 years, most large rivers in North America have been altered for flood control, hydropower, navigation or water supply development. Although these activities clearly provide important human services, their associated environmental disturbances can profoundly affect stream-dwelling organisms. We used dynamic multi-species occupancy models combined with a trait-based approach to estimate the influence of site-level and species-level characteristics on patch dynamic rates for 15 darter species native to the Elk River, a large, flow-regulated Tennessee River tributary in Tennessee and Alabama. Dynamic occupancy modelling results indicated that for every 2.5 °C increase in stream temperature, darters were 3.94 times more likely to colonize previously unoccupied stream reaches. Additionally, large-bodied darter species were 3.72 times more likely to colonize stream reaches compared with small-bodied species, but crevice-spawning darter species were 5.24 times less likely to colonize previously unoccupied stream reaches. In contrast, darters were 2.21 times less likely to become locally extinct for every 2.5 °C increase in stream temperature, but high stream discharge conditions elevated the risk of local extinction. Lastly, the presence of populations in neighbouring upstream study reaches contributed to a lower risk of extinction, whereas the presence of populations in neighbouring downstream study reaches contributed to higher rates of colonization. Our study demonstrates the application of a trait-based approach combined with a metapopulation framework to assess the patch dynamics of darters in a regulated river. Results from our study will provide a baseline for evaluating the ecological consequences of alternative dam operations.

River Research and Applications↗