Geology Reports⌕ Search

SEARCH · Geology Reports

Results for “Experimental Results”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,531 records · Page 85Linked to original sources
USGS2022

Relocated beaver can increase water storage and decrease stream temperature in headwater streams

Many areas are experiencing increasing stream temperatures due to climate change, and some are experiencing reduced summer stream flows and water availability. Because dam building and pond formation by beaver can increase water storage, stream cooling, and riparian ecosystem resilience, beaver have been proposed as a potential climate adaption tool. Despite the large number of studies that have evaluated how beaver activity may affect hydrology and water temperature, few experimental studies have quantified these outcomes following beaver relocation. We evaluated changes in temperature and water storage following the relocation of 69 beaver into 13 headwater stream reaches of the Skykomish River watershed within the Snohomish River basin, Washington, USA. We evaluated how beaver dams affected surface and groundwater storage and stream temperature. Successful relocations created 243 m 3 of surface water storage per 100 m of stream in the first year following relocation. Dams raised water table elevations by up to 0.33 m and stored approximately 2.4 times as much groundwater as surface water per relocation reach. Stream reaches downstream of dams exhibited an average decrease of 2.3°C during summer base-flow conditions. We also assessed how dam age, condition, maintenance frequency, and pond morphology influenced stream temperature at naturally colonized wetland complexes. Our findings demonstrate that dam building can increase water storage and reduce stream temperatures in the first year following successful beaver relocation. Fluvial and floodplain morphology of candidate reaches for relocation is an important consideration because it determines the type and magnitude of response. Relocation to reaches with existing small, abandoned ponds may address thermal criteria by conversion from warming to cooling reaches, whereas relocation within large, abandoned complexes or vacant habitat may result in greater water storage. Although beaver relocation can be an effective climate adaptation strategy to retain more stable hydrologic regimes and water quality in our study area, there appear to be regionally specific environmental and geomorphic factors that influence how beaver affect water storage and temperature. More research is needed to investigate how and why these regional differences affect water storage and stream temperature response in beaver-influenced systems.

Washington↗
USGS2019

In vitro immune function in laboratory-reared age-0 smallmouth bass (Micropterus dolomieu) relative to diet

Smallmouth bass ( Micropterus dolomieu ) are used as an indicator species in environmental monitoring and assessment studies. However, laboratory-based studies for methods development and effector assessment are limited for this species. Nutrition, a known modulator of teleost physiological responses including immune function, is a critical knowledge-gap sometimes overlooked in the design of laboratory studies. We report the results from a study evaluating a commercially available artificial pelleted diet for bass and live feed (fathead minnows). Following a six-month diet-acclimation period, age-0 smallmouth bass were assessed using morphometric measures, histologic and immune-function end points using conventional methods, miniaturized cell isolation and assay methods as well as imaging flow cytometry. Fish on the two diets did not significantly differ in length, weight, or condition factor, indicating that growth was similar in the two groups. Histologic examination revealed relatively higher levels of macrophage aggregates and accumulation of ceroid/lipofuscin in the spleen as well as hepatocyte changes in the pellet-fed group. Leukocytes from the pellet-fed group exhibited significantly elevated bactericidal activity and significantly depressed mitogen response compared to fish fed live feed. Following exposure to a known inducer of inflammatory responses, bacterial lipopolysaccharide, responses including the transition of leukocytes to an apoptotic/necrotic condition differed significantly based on diet. Histologic findings were consistent with the occurrence of diet-related oxidative stress in the pellet-fed fish. Oxidative stress can be induced by multiple factors including environmental pollutants. For a diet to be useful in laboratory-based studies, it cannot elicit response that could also be induced by experimental treatments. To do so greatly complicates the detection of experimental effects. Until an artificial diet is developed for smallmouth bass that does not produce potentially confounding conditions for laboratory-based studies, use of a live feed appears to be the best option.

Fish & Shellfish Immunology↗
USGS2023

Characterization of maternal immunity following vaccination of broodstock against IHNV or Flavobacterium psychrophilum in rainbow trout (Oncorhynchus mykiss)

Infectious hematopoietic necrosis (IHN) is a significant viral disease affecting salmonids, whereas Flavobacterium psychrophilum (Fp), the causative agent of bacterial coldwater disease (BCWD), remains one of the most significant bacterial pathogens of salmonids. We explored maternal immunity in the context of IHN and BCWD management in rainbow trout ( Oncorhynchus mykiss ) aquaculture. Two experimental trials were conducted where different groups of female broodstock were immunized prior to spawning with an IHNV DNA vaccine or a live attenuated F. psychrophilum (Fp B.17-ILM) vaccine alone, or in combination. Progeny were challenged with either a low or high dose of IHNV at 13 days post hatch (dph) and 32 dph or challenged with F. psychrophilum at 13 dph. Mortality following a low-dose IHNV challenge at 13 dph was significantly lower in progeny from vaccinated broodstock vs. unvaccinated broodstock, but no significant differences were observed at 32 dph. Mortality due to BCWD was also significantly reduced in 13 dph fry that originated from broodstock immunized with the Fp B.17-ILM vaccine. After vaccination broodstock developed specific or neutralizing antibodies respectively to F. psychrophilum and IHNV; however, antibody titers in eggs and fry were undetectable. In the eggs and fry mRNA transcripts of the complement components C3 and C5 were detected at much higher levels in progeny from vaccinated broodstock and showed a significantly increased and rapid response post-challenge compared with unvaccinated broodstock. After challenges pro-inflammatory cytokine expression was immediately and considerably elevated in the fry from vaccinated broodstock vs. unvaccinated broodstock, whereas adaptive immune genes were elevated to a lesser degree. Results suggest that maternal transfer of innate and adaptive factors at the transcript level occurred because development of lymphomyeloid organs is not complete in such young fry. In addition to documenting maternally derived immunity in teleosts, this study demonstrates that broodstock vaccination can confer some degree of protection to progeny against viral and bacterial pathogens.

Fish and Shellfish Immunology↗
USGS1971

The relation of turbulence to diffusion in open-channel flows

This investigation examines the interrelation between turbulent diffusion, dispersion, and the statistical properties of turbulence in an open-channel flow. The experiments were conducted in a 3. 87- foot wide flume over four boundary roughnesses. The results are from studies made of: (1) the influence of turbulence on the vertical and lateral diffusion of plumes of heated water and a neutrally-buoyant salt solution from a point source at the mid-depth of flow; (2) the velocity concentration covariance along the axis of a salt solution plume using a single-electrode conductivity probe and hot-film sensor; (3) lateral and longitudinal surface diffusion measured by dropping polyethylene particles on the water surface; and (4) longitudinal space-time velocity correlation measurements. The results of the study substantiate Philip's concept relating the ratio of Eulerian to estimated Lagrangian time scales and the reciprocal of the longitudinal intensity of turbulence. The relation is used to predict coefficients of longitudinal turbulent diffusion at the water surface and in the flow field. A similar concept using an integral time scale based on the longitudinal intensity of turbulence is used to predict coefficients of both surface and depth-averaged turbulent diffusion in three coordinate directions for heated water and neutrally buoyant jets of salt solution. Longitudinal space-time velocity correlation measurements can be used to predict the Lagrangian time scale only under limited conditions. For this study the Lagrangian scale was underpredicted by 250 percent. A model is developed for the behavior of the longitudinal velocity concentration covariance along the axis of a plume of neutrally-buoyant salt solution. The covariance measurements are accurate to ±20 percent . The boussinesq model of scalar transport is verified with an accuracy of ±25 percent by comparing diffusion coefficients from (1) the velocity concentration covariance measurements with (2) those obtained at the water surface using floating particles. The hot-film single-electrode conductivity probe method for measuring the covariance offers a new tool to experimenters in turbulent mass transfer. Under the range of conditions studied, longitudinal diffusion accounts for 4 to 13 percent of the one-dimensional dispersion process. Predictions of the dispersion coefficient by formulas such as Elder's were in error by as much as 50 percent. The exponent in the power-law equation describing the decay of scalar quantities downstream of a jet is a linear function of the shear velocity of the channel. The length of the core region of a jet is a power-law function of the jet strength with the exponent depending on boundary roughness.

Open-File Report↗
USGS2013

Variation in salinity tolerance among larval anurans: implications for community composition and the spread of an invasive, non-native species

Amphibians in freshwater coastal wetlands periodically experience acute exposure to salinity from hurricane-related overwash events, as well as chronic exposure associated with rising sea levels. In a comparative experimental approach, we examined whether seven species of anuran amphibians vary in their tolerance to changes in salinity. In a laboratory study, we exposed larval Hyla cinerea (Green Treefrog), H. squirella (Squirrel Treefrog), Lithobates catesbeianus (American Bullfrog), L. sphenocephalus (Southern Leopard Frog), Anaxyrus terrestris (Southern Toad), and Gastrophryne carolinensis (Eastern Narrow-mouthed Toad) from an inland population in north central Florida, USA, and Osteopilus septentrionalis (Cuban Treefrog) tadpoles from an inland population in southwest Florida, to acute salinity for 72 h. For each species, we replicated trials in which tadpoles were exposed to salinities of 0.2 (control), 5, 10, 12, 14, and 16 ppt. For all species, tadpoles reared in the control and 5 ppt treatments had 96.7–100% survival. No individuals of G. carolinensis survived at salinities exceeding 5 ppt and no individuals of any species survived in the 14 or 16 ppt treatments. For all other native species, survival at 10 ppt ranged from 46.7 to 80%, but declined to 0% at 12 ppt (except for H. cinerea , of which only 3.3% survived at 12 ppt). In contrast, all individuals of the invasive, non-native O. septentrionalis survived exposure to a salinity of 10 ppt, and survival in this species remained relatively high at 12 ppt. Our results illustrate that the non-native O. septentrionalis has a higher salinity tolerance than the native species tested, which may contribute to its invasion potential. Moreover, species commonly associated with coastal freshwater wetlands differ in their salinity tolerances, suggesting that salt water intrusion due to storm surges and sea level rise may affect the species composition of these ecosystems.

Florida↗
USGS2009

A revised burial dose estimation procedure for optical dating of youngand modern-age sediments

The presence of genuinely zero-age or near-zero-age grains in modern-age and very young samples poses a problem for many existing burial dose estimation procedures used in optical (optically stimulated luminescence, OSL) dating. This difficulty currently necessitates consideration of relatively simplistic and statistically inferior age models. In this study, we investigate the potential for using modified versions of the statistical age models of Galbraith et??al. [Galbraith, R.F., Roberts, R.G., Laslett, G.M., Yoshida, H., Olley, J.M., 1999. Optical dating of single and multiple grains of quartz from Jinmium rock shelter, northern Australia: Part I, experimental design and statistical models. Archaeometry 41, 339-364.] to provide reliable equivalent dose (D e ) estimates for young and modern-age samples that display negative, zero or near-zero D e estimates. For this purpose, we have revised the original versions of the central and minimum age models, which are based on log-transformed D e values, so that they can be applied to un-logged D e estimates and their associated absolute standard errors. The suitability of these 'un-logged' age models is tested using a series of known-age fluvial samples deposited within two arroyo systems from the American Southwest. The un-logged age models provide accurate burial doses and final OSL ages for roughly three-quarters of the total number of samples considered in this study. Sensitivity tests reveal that the un-logged versions of the central and minimum age models are capable of producing accurate burial dose estimates for modern-age and very young (<350??yr) fluvial samples that contain (i) more than 20% of well-bleached grains in their D e distributions, or (ii) smaller sub-populations of well-bleached grains for which the D e values are known with high precision. Our results indicate that the original (log-transformed) versions of the central and minimum age models are still preferable for most routine dating applications, since these age models are better suited to the statistical properties of typical single-grain and multi-grain single-aliquot D e datasets. However, the unique error properties of modern-age samples, combined with the problems of calculating natural logarithms of negative or zero-Gy D e values, mean that the un-logged versions of the central and minimum age models currently offer the most suitable means of deriving accurate burial dose estimates for very young and modern-age samples. ?? 2009 Elsevier Ltd. All rights reserved.

Quaternary Geochronology↗
USGS2017

Archive of bathymetry data collected in South Florida from 1995 to 2015

Description Land development and alterations of the ecosystem in south Florida over the past 100 years have decreased freshwater and increased nutrient flows into many of Florida's estuaries, bays, and coastal regions. As a result, there has been a decrease in the water quality in many of these critical habitats, often prompting seagrass die-offs and reduced fish and aquatic life populations. Restoration of water quality in many of these habitats will depend partly upon using numerical-circulation and sediment-transport models to establish water-quality targets and to assess progress toward reaching restoration targets. Application of these models is often complicated because of complex sea floor topography and tidal flow regimes. Consequently, accurate and modern sea-floor or bathymetry maps are critical for numerical modeling research. Modern bathymetry data sets will also permit a comparison to historical data in order to help assess sea-floor changes within these critical habitats. New and detailed data sets also support marine biology studies to help understand migratory and feeding habitats of marine life. This data series is a compilation of 13 mapping projects conducted in south Florida between 1995 and 2015 and archives more than 45 million bathymetric soundings. Data were collected primarily with a single beam sound navigation and ranging (sonar) system called SANDS developed by the U.S. Geological Survey (USGS) in 1993. Bathymetry data for the Estero Bay project were supplemented with the National Aeronautics and Space Administration's (NASA) Experimental Advanced Airborne Research Lidar (EAARL) system. Data from eight rivers in southwest Florida were collected with an interferometric swath bathymetry system. The projects represented in this data series were funded by the USGS Coastal and Marine Geology Program (CMGP), the USGS South Florida Ecosystem Restoration Project- formally named Placed Based Studies, and other non-Federal agencies. The purpose of the data collection for all these projects was to support one or more of the following scientific aspects: numerical model applications, sea floor change analysis, or marine habitat investigations. This report serves as an archive of processed bathymetry sounding data, digital bathymetric contours, digital bathymetric maps, sea floor surface grids, and formal Federal Geographic Data Committee (FGDC) metadata. Refer to the Abbreviations page for explanations of acronyms and abbreviations used in this report. Since 2006, the USGS St. Petersburg Coastal and Marine Science Center (SPCMSC) assigns a unique identifier or Field Activity Number (FAN) for each field data collection. Projects described in this report conducted prior to 2006 do not have a FAN. Data from the 13 projects presented in this report provided critical hydrographic information to support multiple science projects in south Florida. The projects and the types of sounding data collected are: Florida Bay (1995-1999) - single-beam Lake Okeechobee (2001) - single-beam Tampa Bay (2001-2004) - single-beam Caloosahatchee River (2002)- single-beam Estero Bay to Matlacha Pass and offshore to Wiggins Pass (2003) - single-beam and airborne lidar North and Northwest Forks of the Loxahatchee and Lower St. Lucie Rivers (2003) - single-beam South Charlotte Harbor and offshore Sanibel Island (2003-2004) - single-beam Shark River and Trout Creek (2004) - single-beam and interferometric swath Southwest Florida Rivers (2004) - interferometric swath Offshore from Wiggins Pass to Cape Romano (2005) - single-beam Ten Thousand Islands (2009) - single-beam Lemon Bay (2011) - single-beam Southwest Florida Rivers (2015) - interferometric swath

Florida↗
USGS2017

Effectiveness of environmental flows for riparian restoration in arid regions: A tale of four rivers

Environmental flows have become important restoration tools on regulated rivers. However, environmental flows are often constrained by other demands within the river system and thus typically are comprised of smaller water volumes than the natural flows they are meant to replace, which can limit their functional efficacy. We review environmental flow programs aimed at restoring riparian vegetation on four arid zone rivers: the Tarim River in China; the Bill Williams River in Arizona, U.S.; the delta of the Colorado River in Mexico; and the Murrumbidgee River in southern Australia. Our goal is to determine what worked and what did not work to accomplish restoration goals. The lower Tarim River in China formerly formed a “green corridor” across the Taklamakan Desert. The riparian zone deteriorated due to diversion of surface and groundwater for irrigated agriculture. A massive restoration program began in 2000 with release of 1038 million cubic meters of water over the first three years. Groundwater levels rose but the ecological response was less than expected politically, socially and within the scientific community. However, releases continued and by 2015 portions of the original iconic Populus euphratica (Euphrates poplar) forest were reestablished. The natural flow regime of the Bill Williams River was disrupted by construction of a dam in 1968, dramatically reducing peak flows along with associated fluvial processes. As a result, the channel narrowed and riparian vegetation expanded and was comprised largely of an introduced shrub species ( Tamarix spp.). Environmental flow releases including small, managed floods and sustained base flows have been implemented since the mid 1990’s to promote establishment and maintenance of native riparian trees (cottonwoods and willows) and have been successful, although in a “downsized” portion of the valley bottom. Experience from the Bill Williams was used to help design the Minute 319 environmental flow in the delta of the Colorado River in 2014. Water was released as a short, one-time pulse during spring with the intent of starting new cohorts of cottonwood and willow. However, fluvial disturbance was limited by the relatively small magnitude pulse, low flows did not continue throughout the growing season in some reaches, native tree recruitment was low, and most of the new plants recruited were Tamarix . The inundated portion of the floodplain did respond with a temporary increase in greenness as measured by satellite vegetation indices, however. The Murrumbidgee River in Australia is a tributary in the Murray-Darling River Basin, which supports iconic red gum ( Eucalyptus camaldulensis ) forests that depend on near-yearly floods for maintenance. During the recent Millennial Drought (2000–2010) environmental flows were provided on an experimental basis to small portions of the Yanga National Forest to see how much water was needed. As with the Colorado River delta, gains in vegetation vigor as measured by satellite vegetation indices following the flows were temporary. Environmental flows in the Bill Williams were able to restore enough overbank flooding and fluvial disturbance to promote some establishment of new cohorts of trees, but on the Colorado and Murrumbidgee Rivers larger volumes of total flows released over longer periods and targeted restoration will be needed to restore the ecosystems. A measure of success in restoring the Euphrates poplar forest on the Tarim and germinating new chorts of willows on the Bill Williams has been achieved after 15–20 years of environmental flows, but the Colorado River delta and Murrumbidgee Rivers have only received one or two flows. Success in enhancing native trees in the Colorado delta has been achieved in restoration plots, but the Murrumbidgee will require large overbank flows on a continuing schedule to rejuvenate the red gum forest.

Ecological Engineering↗
USGS2025

Infrasonic directivity of monopole, dipole, and bipole ground-surface reflected sources

Infrasound (acoustic waves below 20 Hz) can be used to detect, locate and quantify activity in the atmosphere such as volcanic eruptions and anthropogenic explosions. Attempts to quantify volcanic eruption parameters such as exit velocity, plume height and mass flow rate using infrasound data depend strongly on assumptions of the acoustic source type. Infrasonic sources may produce omnidirectional or directional wavefields, while propagation effects, such as interaction with topography, can induce further wavefield directivity that is measured by field instrumentation. Limited sampling of these wavefields can hinder our ability to infer the underlying source, and thus our understanding of the eruption characteristics. Equivalent sources are often used to represent acoustic source mechanisms and resultant wavefields. In this study, we review equivalent acoustic sources as they pertain to infrasonic scale and wavelengths commonly encountered in very local ( ⁠< 5 km range) geophysical field deployments. We highlight the equivalent infrasonic bipole source that can be induced by ground-reflection of an elevated monopole; we are not aware of any prior infrasound studies that use the bipole source concept. We use analytical and numerical methods to explore source directivity of monopole, dipole and bipole ground-reflected sources at infrasonic frequencies as well as the additional directivity complications introduced by interactions with topography. We illustrate that for typical volcano-infrasound wavelengths, increasing height above the ground as well as increasing source frequency leads to increased wavefield directivity. Numerical modelling using a simple omnidirectional monopole source embedded in topography further illustrates that both horizontal and vertical infrasound directionality can be induced by topography at the distance scales appropriate for local volcano infrasound monitoring. Information summarized in this analytical and numerical exploration of infrasound directivity may be used to help guide future volcano-infrasound field deployments intended to estimate source parameters or quantify wavefield directivity. Analytic solutions for simple whole-space or half-space atmospheres provide useful formulations for planning or initially analysing geophysical field-scale experimental data; however, especially at very local distances from the source ( ⁠< 5 km), 3-D simulations are necessary to account for complex topography commonly encountered in volcano-infrasound applications.

Geophysical Journal International↗
USGS2011

U.S. Geological Survey Karst Interest Group Proceedings, Fayetteville, Arkansas, April 26-29, 2011

Karst aquifer systems are present throughout parts of the United States and some of its territories and are developed in carbonate rocks (primarily limestone and dolomite) that span the entire geologic time frame. The depositional environments, diagenetic processes, and post-depositional tectonic events that form carbonate rock aquifers are varied and complex, involving both biological and physical processes that can influence the development of permeability. These factors, combined with the diverse climatic regimes under which karst development in these rocks has taken place result in the unique dual or triple porosity nature of karst aquifers. These complex hydrologic systems often present challenges to scientists attempting to study groundwater flow and contaminant transport. The concept for developing a Karst Interest Group evolved from the November 1999 National Groundwater Meeting of the U.S. Geological Survey (USGS), Water Resources Division. As a result, the Karst Interest Group was formed in 2000. The Karst Interest Group is a loose-knit grass-roots organization of USGS employees devoted to fostering better communication among scientists working on, or interested in, karst hydrology studies. The mission of the Karst Interest Group is to encourage and support interdisciplinary collaboration and technology transfer among USGS scientists working in karst areas. Additionally, the Karst Interest Group encourages cooperative studies between the different disciplines of the USGS and other Federal agencies, and university researchers or research institutes. This fifth workshop is a joint workshop of the USGS Karst Interest Group and University of Arkansas HydroDays workshop, sponsored by the USGS, the Department of Geosciences at the University of Arkansas in Fayetteville. Additional sponsors are: the National Cave and Karst Research Institute, the Edwards Aquifer Authority, San Antonio, Texas, and Beaver Water District, northwest Arkansas. The majority of funding for the proceedings preparation and workshop was provided by the USGS Groundwater Resources Program, National Cooperative Mapping Program, and the Regional Executives of the Northeast, Southeast, Midwest, South Central and Rocky Mountain Areas. The University of Arkansas provided the rooms and facilities for the technical and poster presentations of the workshop, vans for the field trips, and sponsored the HydroDays banquet at the Savoy Experimental Watershed on Wednesday after the technical sessions.

Scientific Investigations Report↗
USGS1979

Connector well experiment to recharge the Floridan Aquifer, East Orange County, Florida

An experimental connector well, screened in the shallow sand aquifer, finished with open hole in the Floridan aquifer, and cased through the confining layer between the two aquifers, was drilled in east Orange County, Florida, to obtain information on the nature and function of the shallow aquifer as related to connector well operation. The potentiometric surface of the shallow aquifer is about 45 feet higher than the potentiometric surface of the Floridan aquifer; hence water flows by gravity from the shallow aquifer to the Floridan aquifer through the well ' connecting ' the two aquifers. Continuous flow measurement over 10 months shows the well discharge varies seasonally and averages slightly more than 50 gallons per minute. Observation wells show that, except for seasonal variation water levels within the area of influence have reached steady state within measurable limits. Vertical anisotrophy in the shallow aquifer is apparently caused by the shape and (or) arrangement of the sand grains that comprise the shallow aquifer , rather than distinct confining layers of different lithology. Transmissivity of the shallow aquifer at the site is about 600 square feet per day. Extensive dewatering of wetlands in east Orange County by connector wells alone is probably not feasible. Nevertheless, large amounts of water could be channeled to the Floridan aquifer by connector wells. The results of the connector well experiment imply that water is being captured from evapotranspiration and runoff in the vicinity of the connector well. (Woodard-USGS)

Florida↗
USGS1997

Chemical element concentrations in four lichens on a transect entering Voyageurs National Park

A three factor transect study was conducted to test the hypothesis that chemical elements from air emissions in the vicinity of International Falls, Minnesota could not be detected in lichens along a 24 km transect reaching into Voyageurs National Park. It was hypothesized that element concentrations in lichens would decline exponentially downwind and would reach background values at a distance before the park boundary. Four species ( Cladina rangiferina, Evernia mesomorpha, Hypogymnia physodes , and Parmelia sulcata ) were sampled at ten sites for 3 years and 17 chemical elements were measured. The most notable result was a curvilinear geographic trend for many elements, which decreased from International Falls and then increased towards the park. This trend was significant for many anthropogenic elements, including S, Hg, Cd, and Cr, and for all four species. This type of distribution pattern has been observed in Hypogymnia physodes in other studies downwind of a steel mill and an oil refinery. Cladina , a ground-dwelling lichen, generally had lower tissue concentrations of the elements than the three epiphytic species. Tissue concentrations over the 3 years of sampling declined an average of 12%. Sufficient evidence exists to conclude that lichen tissue element concentrations in the vicinity of International Falls may be related to local air emissions, and that an exponential decline of element concentrations downwind of the sources does not apply to this situation.

Minnesota↗
USGS2004

LIDAR optical rugosity of coral reefs in Biscayne National Park, Florida

The NASA Experimental Advanced Airborne Research Lidar (EAARL), a temporal waveform-resolving, airborne, green wavelength LIDAR (light detection and ranging), is designed to measure the submeter-scale topography of shallow reef substrates. Topographic variability is a prime component of habitat complexity, an ecological factor that both expresses and controls the abundance and distribution of many reef organisms. Following the acquisition of EAARL coverage over both mid-platform patch reefs and shelf-margin bank reefs within Biscayne National Park in August 2002, EAARL-based optical indices of topographic variability were evaluated at 15 patch reef and bank reef sites. Several sites were selected to match reefs previously evaluated in situ along underwater video and belt transects. The analysis used large populations of submarine topographic transects derived from the examination of closely spaced laser spot reflections along LIDAR raster scans. At all 15 sites, each LIDAR transect was evaluated separately to determine optical rugosity (Rotran), and the average elevation difference between adjacent points (Av(??E ap)). Further, the whole-site mean and maximum values of Ro tran and Av(??Eap) for the entire population of transects at each analysis site, along with their standard deviations, were calculated. This study revealed that the greater habitat complexity of inshore patch reefs versus outer bank reefs results in relative differences in topographic complexity that can be discerned in the laser returns. Accordingly, LIDAR sensing of optical rugosity is proposed as a complementary new technique for the rapid assessment of shallow coral reefs. ?? Springer-Verlag 2004.

Coral Reefs↗
USGS1994

Airborne remote sensing for geology and the environment; present and future

In 1988, a group of leading experts from government, academia, and industry attended a workshop on airborne remote sensing sponsored by the U.S. Geological Survey (USGS) and hosted by the Branch of Geophysics. The purpose of the workshop was to examine the scientific rationale for airborne remote sensing in support of government earth science in the next decade. This report has arranged the six resulting working-group reports under two main headings: (1) Geologic Remote Sensing, for the reports on geologic mapping, mineral resources, and fossil fuels and geothermal resources; and (2) Environmental Remote Sensing, for the reports on environmental geology, geologic hazards, and water resources. The intent of the workshop was to provide an evaluation of demonstrated capabilities, their direct extensions, and possible future applications, and this was the organizational format used for the geologic remote sensing reports. The working groups in environmental remote sensing chose to present their reports in a somewhat modified version of this format. A final section examines future advances and limitations in the field. There is a large, complex, and often bewildering array of remote sensing data available. Early remote sensing studies were based on data collected from airborne platforms. Much of that technology was later extended to satellites. The original 80-m-resolution Landsat Multispectral Scanner System (MSS) has now been largely superseded by the 30-m-resolution Thematic Mapper (TM) system that has additional spectral channels. The French satellite SPOT provides higher spatial resolution for channels equivalent to MSS. Low-resolution (1 km) data are available from the National Oceanographic and Atmospheric Administration's AVHRR system, which acquires reflectance and day and night thermal data daily. Several experimental satellites have acquired limited data, and there are extensive plans for future satellites including those of Japan (JERS), Europe (ESA), Canada (Radarsat), and the United States (EOS). There are currently two national airborne remote sensing programs (photography, radar) with data archived at the USGS' EROS Data Center. Airborne broadband multispectral data (comparable to Landsat MSS and TM but involving several more channels) for limited geographic areas also are available for digital processing and analysis. Narrow-band imaging spectrometer data are available for some NASA experiment sites and can be acquired for other locations commercially. Remote sensing data and derivative images, because of the uniform spatial coverage, availability at different resolutions, and digital format, are becoming important data sets for geographic information system (GIS) analyses. Examples range from overlaying digitized geologic maps on remote sensing images and draping these over topography, to maps of mineral distribution and inferred abundance. A large variety of remote sensing data sets are available, with costs ranging from a few dollars per square mile for satellite digital data to a few hundred dollars per square mile for airborne imaging spectrometry. Computer processing and analysis costs routinely surpass these expenses because of the equipment and expertise necessary for information extraction and interpretation. Effective use requires both an understanding of the current methodology and an appreciation of the most cost-effective solution.

Bulletin↗
USGS2022

Assessing runoff and erosion on woodland-encroached sagebrush steppe using the Rangeland Hydrology and Erosion Model

The transition of sagebrush-dominated ( Artemisia spp.) shrublands to pinyon ( Pinus spp.) and juniper ( Juniperus spp.) woodlands markedly alters resource-conserving vegetation structure typical of these landscapes. Land managers and scientists in the western United States need knowledge and predictive tools for assessment and effective targeting of tree-removal treatments to conserve or restore sagebrush vegetation and associated hydrologic function. This study developed modeling approaches to quantify the hydrologic vulnerability and erosion potential of sagebrush rangelands in the later stages of woodland encroachment and in response to commonly applied tree-removal treatments. Using experimental data from multiple sites in the Great Basin Region, USA, and process-based knowledge from decade-long vegetation and rainfall simulation studies at those sites, we (1) assessed the capability of the Rangeland Hydrology and Erosion Model (RHEM) to accurately predict patch-scale (12 m 2 ) measured runoff and erosion from tree canopy and intercanopy hydrologic functional units in untreated and burned woodlands 9 years postfire, and (2) developed and evaluated multiple RHEM approaches/frameworks to model aggregated effects of tree canopy and intercanopy areas on patch- and hillslope-scale (50 m length) runoff and erosion processes in untreated and treated (burned, cut, and masticated) woodlands. The RHEM accurately predicted measured runoff and sediment yield from patch-scale rainfall simulations as partitioned on untreated and treated tree canopy and intercanopy areas and effectively parameterized the dominant controls on runoff and erosion process in woodlands. With few exceptions, evaluated hillslope-scale RHEM frameworks similarly predicted reduced hydrologic vulnerability and erosion potential for conditions 9 years following tree removal by burning, cutting, and mastication treatments. Regressions of RHEM-predicted hillslope runoff, sediment, and hydraulic/erosion parameters with bare ground and ground cover attributes indicate all RHEM frameworks effectively represented the dominant controls on hydrologic and erosion processes for rangelands and woodlands. The results provide RHEM frameworks and recommendations for assessing hydrologic vulnerability and erosion potential on woodland-encroached sites and predicting the effectiveness of tree removal to reestablish a water and soil resource-conserving vegetation structure on sagebrush rangelands. We anticipate our RHEM or similar modeling approaches may be applicable to analogous water-limited landscapes elsewhere subject to woody plant encroachment.

Nevada, Utah↗
USGS1983

Connector well experiment to recharge the Floridan aquifer, east Orange County, Florida

An experimental connector well, screened in the shallow sand aquifer, finished with open hole in the Floridan aquifer and cased through the confining layer between the two aquifers, was drilled in east Orange County, Fla., to obtain information on the nature and function of the shallow aquifer as related to connector well operation. The potentiometric surface of the shallow aquifer is about 45 feet higher than the potentiomettic surface of the Floridan aquifer; hence water flows by gravity from the shallow aquifer to the Floridan aquifer through the well 'connecting' the two aquifers. Continuous flow measurement over 10 months shows the well discharge varies seasonally and averages slightly more than 50 gallons per minute. Observation wells show that, except for seasonal variation, water levels within the area of influence have reached steady state within measurable limits. Vertical anisotropy in the shallow aquifer is apparently caused by the shape and (or) arrangement of the sand grains that comprise the shallow aquifer, rather than because of distinct confining layers of different lithology. Transmissivity of the shallow aquifer at the site is about 600 square feet per clay. Extensive dewatering of wetlands in east Orange County by connector wells alone probably is not feasible. Nevertheless, large amounts of water could be channeled to the Floridan aquifer by connector wells. The results of the connector well experiment imply that water is being captured from evapotranspiration and interception of water that would have discharged to swamps in the vicinity of the connector well. However, the data available from this experiment do not permit a quantitative expression of the net gain in recharge to the Floridan aquifer resulting from operation of the connector well.

Water Supply Paper↗
USGS2025

Effects of riparian forest thinning on resident salmonid fishes in coastal northern California catchments

Resource managers are interested in whether thinning second-growth forests may be a viable restoration strategy for stream and riparian habitats, but may be concerned about the potential impacts that increases in stream temperature associated with riparian thinning treatments may have on cold-water salmonid fishes. We evaluated the effects of riparian forest thinning on resident populations of coastal cutthroat trout ( Oncorhynchus clarkii clarkii ) in coastal northern California catchments using a manipulative field experiment with a replicated before-after-control-impact design (pre-treatment data collected in 2016, thinning treatments occurred in 2017, and post-treatment data collected in 2018). Experimental thinning treatments reduced riparian shade by 20%–30% along five 150–200 m stream reaches. To provide a process-based evaluation of the implications of riparian thinning for coastal cutthroat trout, we combined seasonal observations of trout density, biomass, and growth with bioenergetics modelling. Cutthroat trout density increased by 8%–31% and biomass increased by 27%–111% in thinned reaches 1 year post-treatment, but responses varied widely across sites and seasons so did not always differ statistically. Growth rates of cutthroat trout varied more among seasons than among reach types (upstream reference, thinned, and downstream), peaking in spring and overwinter relative to summer. Bioenergetics modelling indicated that cutthroat trout responded to thinning-induced increases in stream temperature and shifts in prey energy density via higher consumption rates (i.e., fish fed more frequently) in thinned reaches. Additionally, reach-scale consumption estimates indicated that the energy intake of cutthroat trout increased at the population level in thinned reaches. However, thinned reaches exhibited relatively small changes in consumption, suggesting that riparian thinning was unlikely to enhance growth opportunities for cutthroat trout, supporting our empirical growth observations. Collectively, our field experiment suggests that salmonid fishes may be resilient to thinning second-growth riparian forests when treatments do not substantially increase water temperatures. Moreover, our results highlight that pairing empirical data with bioenergetics modelling can provide valuable insights into the mechanisms driving fish responses to riparian forest restoration.

California↗
USGS2011

Passage and behavior of adult American shad in an experimental louver bypass system

We tested 436 adult American shad Alosa sapidissima in an experimental louver bypass system, which was similar to a system operating at Holyoke Dam, Massachusetts, to determine guidance and passage efficiency and to study fish response to stimuli from physical structures, light intensity, and water velocity. Groups of 5–29 fish were exposed to combinations of two bypass exits (wide-shallow and vertical-slot sharp-crested weirs) and two louver arrays (7.6- and 15.2-cm slat spacing) oriented 20° to water flow direction. Underwater video observations showed fish responded to louvers as a physical barrier during the day, when they stayed 30–55 cm (1.3 cm/5 klx) away from and oriented parallel to louvers, and as a behavioral barrier at night, when they moved closer to louvers and oriented into the current. Both louver arrays guided fish effectively, (i.e., prevented fish from passing through the slats) 100% for narrow spacing and 97% for wide spacing. Adults avoided moving closer than 0.5 m to either exit type; instead, fish remained 0.8–1.4 bodylengths upstream, depending on light intensity (farther upstream during daytime, similar to behavior at louvers). At exits, water velocity increased from 0.4 m/s to 0.8 m/s or more in a distance of 0.9 m (rate of velocity increase, 0.44 m/s per meter). This rapid velocity increase elicited an avoidance response by fish that resulted in few fish (5%) passing. Our results provide behavioral explanations for the efficient guidance of adult American shad by louvers and for the fishes' avoidance of the exit at the Holyoke Dam. From this, we provide suggestions on how to prevent fish avoidance of exits.

Massachusetts↗