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USGS2023

Predicted aquatic exposure effects from a national urban stormwater study

A multi-agency study of 438 organic and 62 inorganic chemicals measured in urban stormwater during 50 total runoff events at 21 sites across the United States demonstrated that stormwater discharges can generate localized, aquatic exposures to extensive contaminant mixtures, including organics suspected to cause adverse aquatic-health effects. The aggregated risks to multiple aquatic trophic levels (fish, invertebrates, plants) of the stormwater mixture exposures, which were documented in the national study, were explored herein by calculating cumulative ratios of organic-contaminant in vitro exposure–activity cutoffs (∑ EAR ) and health-benchmark-weighted cumulative toxicity quotients (∑ TQ ). Both risk assessment approaches indicated substantial (moderate to high) risk for acute adverse effects to aquatic organisms across multiple trophic levels (fish, macroinvertebrates, non-vascular/vascular plants) at or near stormwater discharge points across the United States. The results are interpreted as potential orders of magnitude underestimates of actual aquatic risk in stormwater control wetlands or in the immediate vicinity of such discharges to surface-water receptors, because the 438 organic-compound analytical space assessed in this study is orders of magnitude less than the 350 000 parent compounds estimated to be in current commercial use globally and the incalculable chemical-space of potential metabolites and degradates.

Environmental Science: Water Research and Technolo↗

USGS1991

A comparison of Sr-Nd-Pb isotopes in young and old continental lithospheric mantle: Patagonia and eastern China

It is commonly accepted that beneath the continental crust lies a keel of lithospheric mantle, which extends 50–200 kilometres downward to a transition zone into the asthenosphere. The chemical and physical properties of this reservoir are best known through studies of the basalts and xenoliths that provide samples of the subcrustal mantle. Although sharing many characteristics with oceanic island basalts, some continental basalts become increasingly distinct isotopically as crustal age increases, strongly supporting a permanent association between crust and mantle. Consequently, the distinctive trace element and isotope composition of the lithospheric mantle is able to give important clues to its origin and evolution. The mantle under newly‐created crust is typified by a radiogenic isotope variability that emphasizes the materials from which the continental lithosphere is assembled. Old lithospheric mantle, on the other hand, exhibits more evolved isotopic patterns that attest to the existence of long‐lived, chemically complex systems. A comparison of the Pb, Sr and Nd isotopes in alkalic to sub‐alkalic basalt derived from Phanerozoic (Patagonia) and Middle Archaean to Early Proterozoic (eastern China) subcrustal mantle is useful for identifying ‘end‐member’ components of the lithosphere. One component, having an isotopic composition close to PREMA, either continues to evolve virtually unchanged after incorporation into the lithosphere or is, itself, a relatively new addition even to old lithosphere. Another component, beginning with the isotopic composition of BSE, undergoes significant reduction in U/Pb and Sm/Nd (but not Rb/Sr) upon incorporation into the lithosphere and, with time, shows an increasingly retarded evolution of 206 Pb/ 204 Pb and negative ε Nd‐values approaching the isotopic composition of EMI. Five models are discussed that relate the isotopic composition of the continental lithospheric mantle to that of other parts of the terrestrial system, which may be involved in its origin and evolution. The potential locations of the contributing components and the mechanisms and timing of their assembly into lithosphere are considered. Current knowledge, however, does not allow us to distinguish unequivocally among the various scenarios for the creation and evolution of this reservoir.

Australian Journal of Earth Sciences↗

USGS2016

Flood-inundation map library for the Licking River and South Fork Licking River near Falmouth, Kentucky

Digital flood inundation maps for a 17-mile reach of Licking River and 4-mile reach of South Fork Licking River near Falmouth, Kentucky, were created by the U.S. Geological Survey (USGS) in cooperation with Pendleton County and the U.S. Army Corps of Engineers–Louisville District. The inundation maps, which can be accessed through the USGS Flood Inundation Mapping Science Web site at http://wim.usgs.gov/FIMI/FloodInundationMapper.html , depict estimates of the areal extent and depth of flooding corresponding to selected water levels (stages) at the USGS streamgage on the Licking River at Catawba, Ky., (station 03253500) and the USGS streamgage on the South Fork Licking River at Hayes, Ky., (station 03253000). Current conditions (2015) for the USGS streamgages may be obtained online at the USGS National Water Information System site ( http://waterdata.usgs.gov/nwis ). In addition, the streamgage information has been provided to the National Weather Service (NWS) for incorporation into their Advanced Hydrologic Prediction Service (AHPS) flood warning system ( http:/water.weather.gov/ahps/ ). The flood hydrograph forecasts provided by the NWS are usually collocated with USGS streamgages. The forecasted peak-stage information, also available on the NWS Web site, may be used in conjunction with the maps developed in this study to show predicted areas of flood inundation. In this study, flood profiles were computed for the Licking River reach and South Fork Licking River reach by using a one-dimensional step-backwater model. The hydraulic model was calibrated by using the most current (2015) stage-discharge relations for the Licking River at Catawba, Ky., and the South Fork Licking River at Hayes, Ky., USGS streamgages. The calibrated model was then used to calculate 60 water-surface profiles for a sequence of flood stages, at 2-foot intervals, referenced to the streamgage datum and ranging from an elevation near bankfull to the elevation associated with a major flood that occurred in the region in 1997. To delineate the flooded area at each interval flood stage, the simulated water-surface profiles were combined with a digital elevation model of the study area by using geographic information system software. The availability of these flood inundation maps for Falmouth, Ky., along with online information regarding current stages from the USGS streamgages and forecasted stages from the NWS, provides emergency management personnel and local residents with information that is critical for flood response activities such as evacuations, road closures, and post-flood recovery efforts.

Kentucky↗

USGS2007

Simulation of flow and habitat conditions under ice, Cache la Poudre River - January 2006

The U.S. Forest Service authorizes the occupancy and use of Forest Service lands by various projects, including water storage facilities, under the Federal Land Policy and Management Act. Federal Land Policy and Management Act permits can be renewed at the end of their term. The U.S. Forest Service analyzes the environmental effects for the initial issuance or renewal of a permit and the terms and conditions (for example, mitigations plans) contained in the permit for the facilities. The U.S. Forest Service is preparing an environmental impact statement (EIS) to determine the conditions for the occupancy and use for Long Draw Reservoir on National Forest System administered lands. The scope of the EIS includes evaluating current operations and effects to fish habitat of an ongoing winter release of 0.283 m3 /s (10 ft3 /s) from headwater reservoirs as part of a previously issued permit. The field conditions observed during this study included this release. The U.S. Forest Service entered into an interagency agreement (05-IA-11021000-030) with the U.S. Geological Survey (USGS) Fort Collins Science Center to perform analysis of fish habitat and flow relationships in the Cache la Poudre River during winter ice-over conditions using a twodimensional hydrodynamic model. The U.S. Forest Service selected the Fort Collins Science Center for this task because of their expertise in developing two-dimensional hydraulic models for habitat modeling applications. This report transmits model results to the U.S. Forest Service to analyze the effects of alternative flow scenarios at a site on the mainstem Cache la Poudre River in Larimer County, Colorado, near Kinikinik (40° 42' 44.16" N. lat, 105° 44' 30.70" W. log), as shown in figure 1. It will be used in pending environmental analyses and decisions for the occupancy and use of the Arapaho-Roosevelt National Forest by water storage facilities. The water management scenarios of interest in this study are related to releasing water from Chambers and Barnes Meadows Reservoirs, based on the assumption that winter flow augmentation can increase potential fish habitat. Figure 2 shows the relationship between Chambers, Barnes Meadows, and Long Draw Reservoirs. At the time this study was proposed, existing flow simulation results showed that the channel constraints imposed by existing artificial low-head dikes would have little or no effect on the hydrodynamics of the river at the low flow levels that were to be evaluated. The Kinikinik study site contains deep pools, riffles, and runs. This diversity of habitat types made it ideal for assessing the effects of altered flow on fish habitat under ice in the main stem Cache la Poudre River. Thus, the Kinikinik site was selected for this study of winter habitat conditions. The preexisting topographic and hydrologic data collected at this site enabled data collection efforts for this study to focus on describing streamflow and ice cover during the winter months. A two-dimensional hydrodynamic model, River2D (Steffler and Blackburn, 2002), was used to simulate flow conditions under the ice cover that was observed January 24, 2006. The objectives of this study are (1) to describe the extent and thickness of ice cover, (2) simulate depth and velocity under ice at the study site for observed and reduced flows, and (3) to quantify fish habitat in this portion of the mainstem Cache la Poudre River for the current winter release schedule as well as for similar conditions without the 0.283 m 3 /s winter release.

Colorado↗

USGS2001

Tampa Bay Integrated Science Pilot Study: wetland characterization

Coastal wetlands in Tampa Bay consist of mangrove forest and tidal salt marsh. Wetlands buffer storm surges, provide fish and wildlife habitat, and enhance water quality through the removal of water-borne nutrients and contaminants. Substantial areas of both mangrove and salt marsh have been lost to agricultural, residential and industrial development in this urban estuary. Wetlands restoration has been initiated in Tampa Bay. Baseline studies on the current condition of wetlands and historical and prehistorical information is needed for successful restoration planning and evaluation. A major objective of this component of the Tampa Bay pilot program was to characterize wetlands in Tampa Bay beginning with areas that differ in their degree of human-induced disturbance ( Fig. 1 ). The Alafia River area is urbanized, industrialized and dredged, whereas the Terra Ceia area has a history of agricultural use with associated soil berms and mosquito ditches, but has not been farmed for at least 20 years ( Fig. 2 ).

Open-File Report↗

USGS2005

Water availability for the Western United States--Key scientific challenges

In the Western United States, the availability of water has become a serious concern for many communities and rural areas. Near population centers, surface-water supplies are fully appropriated, and many communities are dependent upon ground water drawn from storage, which is an unsustainable strategy. Water of acceptable quality is increasingly hard to find because local sources are allocated to prior uses, depleted by overpumping, or diminished by drought stress. Some of the inherent characteristics of the West add complexity to the task of securing water supplies. The Western States, including the arid Southwest, have the most rapid population growth in the United States. The climate varies widely in the West, but it is best known for its low precipitation, aridity, and drought. There is evidence that the climate is warming, which will have consequences for Western water supplies, such as increased minimum streamflow and earlier snowmelt events in snow-dominated basins. The potential for departures from average climatic conditions threatens to disrupt society and local to regional economies. The appropriative rights doctrine governs the management of water in most Western States, although some aspects of the riparian doctrine are being incorporated. The 'use it or lose it' provisions of Western water law discourage conservation and make the reallocation of water to instream environmental uses more difficult. The hydrologic sciences have defined the interconnectedness of ground water and surface water, yet these resources are still administered separately by most States. The definition of water availability has been expanded to include sustaining riparian ecosystems and individual endangered species, which are disproportionately represented in the Western States. Federal reserved rights, common in the West because of the large amount of Federal land, exist with quite senior priority dates whether or not water is currently being used. A major challenge for water users in the West is that these reserved rights may supersede other existing users. The minimum amount of water required, however, to sustain native peoples, a riparian system, or an endangered species eventually will need to be known in order to manage the available water supply. Periodic inventory and assessment of the amounts and trends of water available in surface water and ground water are needed to support water management. There is a widespread perception that the amount of available water is diminishing with time. This and other perceptions about water availability should be replaced by objective data and analysis. Some data are presented here for the major Western rivers that show that flows are not decreasing in most streams and rivers in the West. Systematic information is lacking to make broad assessments of ground-water availability, but available data for specific aquifers indicate that these aquifers are being depleted, especially near population centers. The complexity added to the issue of Western water availability by these and other factors gives rise to a significant role of science. Science has played a role in support of Western water development from the beginning, and the role has evolved and changed over time as society's values have changed. In this report, the role of science is discussed in three phases: (1) development and construction, (2) consequences and environmental awareness, and (3) sustainability. The development and construction phase includes some historical accounting of water development in the West and shows how some precedents set in those early days are still applied today.

western United States↗

USGS2023

U.S. Geological Survey science vision for native freshwater mussel research in the United States

Executive Summary North America is a global center for native freshwater mussel (order Unionida, hereinafter “mussels”) diversity, with more than 350 species. Mussels are among the most imperiled fauna on the planet. Reasons for both local and widespread declines in mussels are mostly unknown, although the threats may include habitat loss and fragmentation, diseases, environmental contaminants, altered flow regimes, migration barriers to larval hosts, non-native species, and climate change. Over the past three decades, research on mussels has been substantial. Nevertheless, current conservation and management efforts are limited by significant information gaps. For example, the effects of emerging stressors on mussels are largely unknown and identifying when habitats are rehabilitated and suitable for reestablishment of mussels remains challenging. Additionally, historical and current information on the distribution, taxonomy, and life histories are often unreliable or lacking altogether, and more reliable information is needed for many species. We identified focal research themes, goals, and objectives where research on mussels is needed based on information gaps identified through conversations with resource partners across local, regional, and national organizations. Research on biodiversity seeks to enhance the diversity of mussel species and populations to support healthy aquatic ecosystems. Research on emerging stressors seeks to improve the understanding of how mussel species, populations, and communities respond to emerging stressors, including environmental contaminants and climate change. Research on conservation seeks to enhance the recovery of species and populations and to identify data gaps limiting the conservation of mussels and their habitats. Mussels are in urgent need of proactive conservation because they are an integral part of our natural heritage, enhance biodiversity, and provide vital ecological services that support freshwater ecosystems. The U.S. Geological Survey (USGS) has been, and continues to be, a leader in mussel research. Although the USGS is well suited to address the broad-scale multidisciplinary research needed to conserve mussels, the USGS has had substantial loss of scientists with mussel expertise over the past 20 years. However, the breadth of the USGS expertise on mussels can be leveraged internally across other USGS mission and program areas and externally across research partners. Given the breadth and scope of the issues facing mussels across the United States, the research themes outlined in this science vision can only be accomplished through extensive collaborations between the USGS and the full spectrum of natural resource partners, including other Federal and State agencies, Tribal organizations, universities, industries, and nongovernmental organizations.

Circular↗

USGS2025

Review: The hydrogeology of critical mineral resources relevant to the energy transition

Attaining the goals of the international treaty on climate change (the Paris Agreement) will greatly increase the demand for the critical minerals required to implement clean-energy technologies. This poses both challenges and opportunities to the hydrogeologic community from several perspectives. Here, important insights that the hydrogeological sciences have to offer for mineral exploration, mineral production, and addressing environmental issues related to mining and mine decommissioning are summarized. This study focuses on copper, cobalt, lithium, and rare earths to represent the broad spectrum of critical minerals and illustrate their relevance by referring to projected demands and production rates. The current understanding of the hydrogeologic processes that form major deposits of these minerals are then summarized. Ore is defined as the naturally occurring material from which minerals of economic value can be extracted, where most ore deposits are the products of complex hydrogeologic couplings between fluid flow, heat transport, solute transport, chemical reactions, and mechanical deformation. Exploration models for the discovery of deeper, hidden deposits are potentially informed by hydrogeologic theory and hydrogeochemical processes. Hydrogeologic understanding and methods are also essential to production and recovery. Longstanding challenges are mine dewatering and (conversely) mine water supply, as well as mineral-extraction practices such as spoil heap leaching and in situ mining. New challenges arise from element extraction from subsurface brines. Finally, the quantity of water use and potential environmental impacts of mining on water quality are at the core of ‘social license’: the approval and acceptance of society to mining activities.

Hydrogeology Journal↗

USGS2013

Assessing hazards along our Nation's coasts

Coastal areas are essential to the economic, cultural, and environmental health of the Nation, yet by nature coastal areas are constantly changing due to a variety of events and processes. Extreme storms can cause dramatic changes to our shorelines in a matter of hours, while sea-level rise can profoundly alter coastal environments over decades. These changes can have a devastating impact on coastal communities, such as the loss of homes built on retreating sea cliffs or protective dunes eroded by storm waves. Sometimes, however, the changes can be positive, such as new habitat created by storm deposits. The U.S. Geological Survey (USGS) is meeting the need for scientific understanding of how our coasts respond to different hazards with continued assessments of current and future changes along U.S. coastlines. Through the National Assessment of Coastal Change Hazards (NACCH), the USGS carries out the unique task of quantifying coastal change hazards along open-ocean coasts in the United States and its territories. Residents of coastal communities, emergency managers, and other stakeholders can use science-based data, tools, models, and other products to improve planning and enhance resilience.

Fact Sheet↗

USGS2010

Earthquakes in South Carolina and Vicinity 1698-2009

This map summarizes more than 300 years of South Carolina earthquake history. It is one in a series of three similar State earthquake history maps. The current map and the previous two for Virginia and Ohio are accessible at http://pubs.usgs.gov/of/2006/1017/ and http://pubs.usgs.gov/of/2008/1221/. All three State earthquake maps were collaborative efforts between the U.S. Geological Survey and respective State agencies. Work on the South Carolina map was done in collaboration with the Department of Geological Sciences, University of South Carolina. As with the two previous maps, the history of South Carolina earthquakes was derived from letters, journals, diaries, newspaper accounts, academic journal articles, and, beginning in the early 20th century, instrumental recordings (seismograms). All historical (preinstrumental) earthquakes that were large enough to be felt have been located based on felt reports. Some of these events caused damage to buildings and their contents. The more recent widespread use of seismographs has allowed many smaller earthquakes, previously undetected, to be recorded and accurately located. The seismicity map shows historically located and instrumentally recorded earthquakes in and near South Carolina

Open-File Report↗

USGS2024

Methods for computing water-quality concentrations and loads at sites operated by the U.S. Geological Survey Kansas Water Science Center

The U.S. Geological Survey (USGS) Kansas Water Science Center (KSWSC) has published time-series computations of water-quality concentrations and loads based on in situ sensor data since 1995. Water-quality constituent concentrations or densities are computed using regression models that relate in situ sensor values to laboratory analyses of periodically collected samples. These regression models currently (2024) follow no uniform published guidance and are individually documented through USGS reports. This report describes updated (2024) procedures designed to improve the consistency, quality, and timeliness of computed continuous water-quality data produced by the USGS KSWSC. Beginning in 2024, models developed by the USGS KSWSC that follow specific procedures and requirements related to sample collection, model fit, and model documentation outlined in this report are planned to be published and stored in the USGS National Real-Time Water Quality Data for the Nation Data Service. This report also describes USGS KSWSC procedures for evaluating and publishing time-series water-quality computations after initial model development and documentation. This guidance can be used to improve USGS KSWSC model development and data computation consistency and streamline the time-series water-quality computation process from model development to publication.

Open-File Report↗

USGS2020

Simulation of discharge, water-surface elevations, and water temperatures for the St. Louis River estuary, Minnesota-Wisconsin, 2016–17

The St. Louis River estuary is a large freshwater estuary, next to Duluth, Minnesota, that encompasses the headwaters of Lake Superior. The St. Louis River estuary is one of the most complex and compromised near-shore systems in the upper Great Lakes with a long history of environmental contamination caused by logging, mining, paper mills, and other heavy industrial activities. Presently (2020), a widely available, science-based assessment tool capable of evaluating ecosystem-level responses to remediation and restoration projects has not existed for the estuary. To address this need, the U.S. Geological Survey (USGS) built a predictive, mechanistic, three-dimensional hydrodynamic model for the estuary using the Environmental Fluid Dynamics Code framework. In the current version, the model can simulate continuous discharge, water-surface elevations, water temperature, and flow velocity, although the modular framework allows for future additions of water-quality modeling. The model was calibrated using data collected from April 2016 through November 2016 and validated with data collected from April 2017 through November 2017. The four types of data used to evaluate model performance were water-surface elevations, discharge, water temperature, and flow velocities. Streamflow and temperature boundary condition data included a mixture of USGS streamgage data, Minnesota Department of Natural Resources gage data, and estimates derived from the gage data. The model was able to simulate the water-surface elevations with generally good agreement between the simulated and measured values for both years at the daily time step. Specifically, the model was able to demonstrate excellent agreement with the measured data with Nash-Sutcliffe efficiency coefficients greater than 0.8 for all three locations; however, the model was unable to produce hourly water-surface elevations with such accuracy for 2016–17. Discharge was more dynamic than the water-surface elevations, both for the measured and simulated data. Generally, most of the discharge ranged from −650 to 1,200 cubic meters per second, but the constantly changing flux exiting the estuary into Lake Superior (positive flows) and entering the estuary from Lake Superior (negative flows) occurred throughout the year. Even upstream at the St. Louis River at Oliver, Wisconsin, gage (USGS station 0402403250), the effect of flows into the estuary from Lake Superior did occur, demonstrating the strong effect of the Lake Superior seiche on flows for the estuary. From a performance standpoint, the model was able to simulate discharge with generally good agreement in both years, although the 2017 validation was better than the 2016 calibration period. For the daily Nash-Sutcliffe efficiency coefficients, the simulated values were 0.98, 0.62, 0.49, and 0.71 for the Oliver gage; the Superior Bay entry channel at Superior, Wisc., (USGS station 464226092005600); the Superior Bay Duluth Ship Canal at Duluth, Minn., (USGS station 464646092052900); and total entries (combination of the Superior entry and Duluth entry), respectively. For the hourly evaluation criteria, the model performed poorly, with Nash-Sutcliffe efficiency coefficients less than 0 for the two entries into Lake Superior; therefore, as a predictor of discharge at the hourly scale, the model performed worse than using the measured data average. Similar to discharge, the model was a good predictor of flow velocity at the daily time scale but had difficulty matching the measured data at the hourly scale. For discharge and flow velocity, matching at subdaily time steps for a system as complicated as the St. Louis River estuary is considered difficult because the match is highly sensitive to coordinating the exact measurement location to the simulated value. The final calibration target was water temperature, calibrated for the Oliver gage and the Duluth entry. For calibration purposes, the Duluth entry was the more important water temperature target because the Oliver gage was more of an internal check on the model. The Nash-Sutcliffe efficiency coefficients for the Duluth entry were high; hourly Nash-Sutcliffe efficiency coefficients at the Duluth entry were either at or greater than 0.7 for both years, and daily values were 0.84 and 0.82 for 2016 and 2017, respectively.

Minnesota, Wisconsin↗

USGS1995

Handbook of ecotoxicology

The Handbook of Ecotoxicology offers 34 chapters with contributions from over 50 selected international experts. The book is divided into four major sections: I. Quantifying and Measuring Ecotoxicological Effects, II. Contaminant Sources and Effects, III. Case Histories and Ecosystem Surveys, and IV. Methods for Making Estimates and Predictability in Ecotoxicology. Concepts and methodology are presented for many types of aquatic and terrestrial ecotoxicity test protocols for both controlled and field assessments. Chapters are offered on such diverse topics as sediment and soil ecotoxicity, landscape indicators, biomonitoring, and use of current bioindicators. The roles of deforestation and global warming, pathogens and disease in ecotoxicology, abiotic factors, urban runoff, predictive ecotoxicology, population modeling, and restoration ecology are discussed. This book was designed to serve as a reference book for students entering the fields of ecotoxicology, aquatic toxicology, terrestrial wildlife toxicology, and other environmental sciences. Many portions of this handbook will serve as a convenient reference text for established investigators, resource managers, and those involved in risk assessment and risk management within regulatory agencies and the private sector.

Book↗

USGS2025

Biodiversity on public lands: How community science can help

Species inventories are crucial for conservation but are difficult to assemble and maintain. Bioblitzes, which encourage the public to document biodiversity in a particular area and timeframe, may offer useful information but their integration with other datasets poses challenges. We investigated the potential contribution of bioblitzes to natural resource management using observations from the United States National Park Service (NPS) 2016 Centennial Bioblitz. Through automated cross-referencing over 19,000 iNaturalist “research-grade” observations from 107 national parks with existing park inventory lists, we matched 86% of species documented in the Bioblitz to NPS species lists, based on current taxonomy, and matched another 6% of species using alternative scientific names using our matching process in R. Of the remaining 13.5% that did not match the NPS species lists, we manually found that 84% of the unmatched species were found within the lists or were outside the boundaries of the park, identifying 141 native species that were unrecorded in NPS species lists. Many introduced species were recorded; they were more likely to be documented in parks closer to cities. Parks near cities also drew more participants. Our study shows how public participation, through iNaturalist and bioblitzes, can facilitate biodiversity monitoring across large spatial scales.

Conservation Science and Practice↗

USGS2022

Editorial: Plant phenology shifts and their ecological and climatic consequences

Climate change is causing plant phenology to shift, with consequences for ecosystems and the Earth’s climate. Over the last decades, the timing of many important phenological events has advanced in spring, such as leaf emergence and flowering, or been delayed in fall, such as leaf coloration and leaf fall. The consequences of such phenological shifts are still largely unknown, but are hypothesized to have cascading effects on ecosystems, carbon and water cycles, and Earths’ climate. With this research topic, we aimed to synthesize and inspire innovative research in plant phenology to address research questions and challenges on the consequences of phenological shifts on ecosystem function and local hydrology. The articles presented here improve our understanding of the physiological mechanisms responsible for the current phenological changes in spring and fall and provide insight into some of the consequences of these changes on hydrological cycles and ecosystem functioning.

Frontiers in Plant Science↗

USGS2001

Relations among geology, physiography, land use, and stream habitat conditions in the Buffalo and Current River systems, Missouri and Arkansas

This study investigated links between drainage-basin characteristics and stream habitat conditions in the Buffalo National River, Arkansas and the Ozark National Scenic Riverways, Missouri. It was designed as an associative study - the two parks were divided into their principle tributary drainage basins and then basin-scale and stream-habitat data sets were gathered and compared between them. Analyses explored the relative influence of different drainage-basin characteristics on stream habitat conditions. They also investigated whether a relation between land use and stream characteristics could be detected after accounting for geologic and physiographic differences among drainage basins. Data were collected for three spatial scales: tributary drainage basins, tributary stream reaches, and main-stem river segments of the Current and Buffalo Rivers. Tributary drainage-basin characteristics were inventoried using a Geographic Information System (GIS) and included aspects of drainage-basin physiography, geology, and land use. Reach-scale habitat surveys measured channel longitudinal and cross-sectional geometry, substrate particle size and embeddedness, and indicators of channel stability. Segment-scale aerial-photo based inventories measured gravel-bar area, an indicator of coarse sediment load, along main-stem rivers. Relations within and among data sets from each spatial scale were investigated using correlation analysis and multiple linear regression. Study basins encompassed physiographically distinct regions of the Ozarks. The Buffalo River system drains parts of the sandstone-dominated Boston Mountains and of the carbonate-dominated Springfield and Salem Plateaus. The Current River system is within the Salem Plateau. Analyses of drainage-basin variables highlighted the importance of these physiographic differences and demonstrated links among geology, physiography, and land-use patterns. Buffalo River tributaries have greater relief, steeper slopes, and more streamside bluffs than the Current River tributaries. Land use patterns in both river systems correlate with physiography - cleared land area is negatively associated with drainage-basin average slope. Both river systems are dominantly forested (0-35 per-cent cleared land), however, the potential for landscape disturbance may be greater in the Buffalo River system where a larger proportion of cleared land occurs on steep slopes (>15 degrees). When all drainage basins are grouped together, reach-scale channel characteristics show the strongest relations with drainage-basin physiography. Bankfull channel geometry and residual pool dimensions are positively correlated with drainage area and topographic relief variables. After accounting for differences in drainage area, channel dimensions in Buffalo River tributaries tend to be larger than in Current River tributaries. This trend is consistent with the flashy runoff and large storm flows that can be generated in rugged, sandstone-dominate terrain. Substrate particle size is also most strongly associated with physiography; particle size is positively correlated with topographic relief variables. When tributaries are subset by river system, relations with geology and land use variables become apparent. Buffalo River tributaries with larger proportions of carbonate bedrock and cleared land area have shallower channels, better-sorted, gravel-rich substrate, and more eroding banks than those with little cleared land and abundant sandstone bedrock. Gravel-bar area on the Buffalo River main stem was also larger within 1-km of carbonate-rich tributary junctions. Because geology and cleared land are themselves correlated, relations with anthropogenic and natural factors could often not be separated. Channel characteristics in the Current River system show stronger associations with physiography than with land use. Channels are shallower and have finer substrates in the less rugged, karst-rich, western basins than in the

Arkansas, Missouri↗

USGS2011

Search for and limits on plume activity on Mimas, Tethys, and Dione with the Cassini Visual Infrared Mapping Spectrometer (VIMS)

Cassini Visual Infrared Mapping Spectrometer (VIMS) observations of Mimas, Tethys, and Dione obtained during the nominal and extended missions at large solar phase angles were analyzed to search for plume activity. No forward scattered peaks in the solar phase curves of these satellites were detected. The upper limit on water vapor production for Mimas and Tethys is one order of magnitude less than the production for Enceladus. For Dione, the upper limit is two orders of magnitude less, suggesting this world is as inert as Rhea (Pitman, K.M., Buratti, B.J., Mosher, J.A., Bauer, J.M., Momary, T., Brown, R.H., Nicholson, P.D., Hedman, M.M. [2008]. Astrophys. J. Lett. 680, L65–L68). Although the plumes are best seen at ∼2.0 μm, Imaging Science Subsystem (ISS) Narrow Angle Camera images obtained at the same time as the VIMS data were also inspected for these features. None of the Cassini ISS images shows evidence for plumes. The absence of evidence for any Enceladus-like plumes on the medium-sized saturnian satellites cannot absolutely rule out current geologic activity. The activity may below our threshold of detection, or it may be occurring but not captured on the handful of observations at large solar phase angles obtained for each moon. Many VIMS and ISS images of Enceladus at large solar phase angles, for example, do not contain plumes, as the active “tiger stripes” in the south pole region are pointed away from the spacecraft at these times. The 7-year Cassini Solstice Mission is scheduled to gather additional measurements at large solar phase angles that are capable of revealing activity on the saturnian moons.

Icarus↗

USGS2011

Key science issues in the central and eastern United States for the next version of the USGS National Seismic Hazard Maps

The USGS National Seismic Hazard Maps are updated about every six years by incorporating newly vetted science on earthquakes and ground motions. The 2008 hazard maps for the central and eastern United States region (CEUS) were updated by using revised New Madrid and Charleston source models, an updated seismicity catalog and an estimate of magnitude uncertainties, a distribution of maximum magnitudes, and several new ground-motion prediction equations. The new models resulted in significant ground-motion changes at 5 Hz and 1 Hz spectral acceleration with 5% damping compared to the 2002 version of the hazard maps. The 2008 maps have now been incorporated into the 2009 NEHRP Recommended Provisions, the 2010 ASCE-7 Standard, and the 2012 International Building Code. The USGS is now planning the next update of the seismic hazard maps, which will be provided to the code committees in December 2013. Science issues that will be considered for introduction into the CEUS maps include: 1) updated recurrence models for New Madrid sources, including new geodetic models and magnitude estimates; 2) new earthquake sources and techniques considered in the 2010 model developed by the nuclear industry; 3) new NGA-East ground-motion models (currently under development); and 4) updated earthquake catalogs. We will hold a regional workshop in late 2011 or early 2012 to discuss these and other issues that will affect the seismic hazard evaluation in the CEUS.

Conference Paper↗