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At least 667 records · Page 37Linked to original sources
USGS2021

Developing bare-earth digital elevation models from structure-from-motion data on barrier islands

Unoccupied aerial systems can collect aerial imagery that can be used to develop structure-from-motion products with a temporal resolution well-suited to monitoring dynamic barrier island environments. However, topographic data created using photogrammetric techniques such as structure-from-motion represent the surface elevation including the vegetation canopy . Additional processing is required for estimating bare-earth elevation, which is critical for understanding the underlying geomorphology of these islands. In this study, we used a vegetation and elevation survey to produce bare-earth digital elevation models from structure-from-motion-derived elevation products for two sites on Dauphin Island, Alabama (USA). One site was exposed to high wave energy and included a mix of beach, dune, and barrier flat habitats that were dominated by supratidal/upland herbaceous vegetation. The second site was exposed to low wave energy and was dominated by intertidal marsh. Aerial imagery was collected in late fall of 2018 and spring of 2019. We tested several machine learning algorithms for predicting and removing elevation bias for vegetated areas using predictors that included spectral indices from unoccupied aerial systems-based multispectral imagery and landscape position information (e.g., relative topography and distance from shore). Models were developed for each site and season. We also explored how well the model from one season generalized to data from a different season for the same site. For developing initial digital surface models, we found that utilizing a minimum bin algorithm, as opposed to interpolation, led to lower elevation bias. For bias removal, Gaussian process regression performed the best and led to a root mean square error for the bare-earth digital elevation models of around 0.10 m for the high energy site and 0.15 m for the low energy site. Compared to the digital surface models, the root mean square error for the bare-earth digital elevation models was reduced by at least 29 percent for the high energy site and 69 percent for the low energy site. For all models, common predictors included surface elevation, vegetation greenness, and distance from the shoreline. The models produced comparable results when trained using data from a different season. The error estimates for all analyses were within published elevation standards for lidar data for vegetated areas. With calibration, this approach could be portable to other areas or data, such as aerial lidar (conventional or unoccupied), to provide an efficient and repeatable framework for monitoring geomorphology or provide baseline elevations for predicting changes to these environments under future conditions.

Alabama↗
USGS2025

Long-term trends of streamwater chemistry in an agricultural watershed: Effects of anthropogenic and climatic factors

The chemistry of headwater streams is a key indicator of the health of riparian zones and surrounding terrestrial ecosystems. This chemistry is shaped by biogeochemical processes, including chemical weathering, and anthropogenic activities that interact with one another and are sensitive to climate. Elucidating trends in streamwater chemistry and the drivers that underpin them is essential for informing land-management decisions and anticipating water-quality issues that may affect downstream waters. In this work, we investigated the effects of anthropogenic and climatic factors on long-term variations in the chemistry of a first-order stream draining an agricultural catchment nested within the Sleepers River Research Watershed in Vermont, USA. We observed statistically significant increases in alkalinity and the concentrations of calcium and magnesium over a 31-year period for which 17 years of measurements were available. Through the application of generalized linear models, we found that the upward trends in alkalinity and calcium were associated with rising air temperatures, while a response to historical acid deposition played a minor role. We hypothesize that increased production of biogenic carbon dioxide and organic acids in soil and groundwater may lead to increases in chemical weathering rates under warmer climate conditions. This study emphasizes the important role of rising temperatures in the long-term increase in streamwater alkaline solutes, potentially overshadowing other influences like acidification recovery and agricultural practices. It also highlights the importance of comprehensive, long-term research to understand climate impacts on chemical weathering and inland water chemistry, which is critical for managing water quality and understanding regional and global carbon cycles.

Vermont↗
USGS1971

Sierra Nevada plutonic cycle: Part II, tidal energy and a hypothesis for orogenic-epeirogenic periodicities

The dissipative power of the solid earth tides is the order of 10 19 ergs/sec, or a few percent of terrestrial heat flow. It is proposed that this energy is concentrated along oceanic ridge systems and in the asthenosphere by mechanisms of viscous dissipation involving shear melting. Tidal energy localizes and sustains sources of sea-floor spreading through the melting mechanism, convection and magmatic transfer. Components of this energy enter the continent as magmatic heat either where ridge type sources and continents interact or where lateral motions induce shear zones and viscous dissipation within the continent. Temporal maxima of igneous intrusion into continental crust and related epeirogenic oscillations, spaced at intervals of about 30 m.y., are explained in terms of periodic thermal instabilities in the process of shear melting in the mantle. That is, maxima in rates of magma production in the mantle are relieved by vertical magmatic transfer. This process is coupled with lateral motions of the continent in a way analogous to episodic creep episodes of much shorter period in motions of active fault systems. Calculated periodicities are found to be simultaneously compatible with (l) the Sierra Nevada intrusive epochs of Part I, (2) oscillations in the eustatic curve during the Mesozoic Era, (3) concepts of sea-floor spreading, and (4) the magnitude of tidal power. More profound epeirogenic oscillations, having periods of about 200 m.y., are induced by variations in proportioning of tidal energy dissipation between the solid earth and the epicontinental seas. Thus, the tidal deformations of the earth provide information that leads to a general dynamic theory where magmatism, orogency, epeirogeny, sea-floor spreading and continent migration are systematically interrelated.

California↗
USGS2010

Nitrous oxide emission from denitrification in stream and river networks

Nitrous oxide (N 2 O) is a potent greenhouse gas that contributes to climate change and stratospheric ozone destruction. Anthropogenic nitrogen (N) loading to river networks is a potentially important source of N 2 O via microbial denitrification that converts N to N 2 O and dinitrogen (N 2 ). The fraction of denitrified N that escapes as N 2 O rather than N 2 (i.e., the N 2 O yield) is an important determinant of how much N 2 O is produced by river networks, but little is known about the N 2 O yield in flowing waters. Here, we present the results of whole-stream 15 N-tracer additions conducted in 72 headwater streams draining multiple land-use types across the United States. We found that stream denitrification produces N 2 O at rates that increase with stream water nitrate (NO 3 − ) concentrations, but that <1% of denitrified N is converted to N 2 O. Unlike some previous studies, we found no relationship between the N 2 O yield and stream water NO 3 − . We suggest that increased stream NO 3 − loading stimulates denitrification and concomitant N 2 O production, but does not increase the N 2 O yield. In our study, most streams were sources of N 2 O to the atmosphere and the highest emission rates were observed in streams draining urban basins. Using a global river network model, we estimate that microbial N transformations (e.g., denitrification and nitrification) convert at least 0.68 Tg·y −1 of anthropogenic N inputs to N 2 O in river networks, equivalent to 10% of the global anthropogenic N 2 O emission rate. This estimate of stream and river N 2 O emissions is three times greater than estimated by the Intergovernmental Panel on Climate Change. Humans have more than doubled the availability of fixed nitrogen (N) in the biosphere, particularly through the production of N fertilizers and the cultivation of N-fixing crops ( 1 ). Increasing N availability is producing unintended environmental consequences including enhanced emissions of nitrous oxide (N 2 O), a potent greenhouse gas ( 2 ) and an important cause of stratospheric ozone destruction ( 3 ). The Intergovernmental Panel on Climate Change (IPCC) estimates that the microbial conversion of agriculturally derived N to N 2 O in soils and aquatic ecosystems is the largest source of anthropogenic N 2 O to the atmosphere ( 2 ). The production of N 2 O in agricultural soils has been the focus of intense investigation (i.e., >1,000 published studies) and is a relatively well constrained component of the N 2 O budget ( 4 ). However, emissions of anthropogenic N 2 O from streams, rivers, and estuaries have received much less attention and remain a major source of uncertainty in the global anthropogenic N 2 O budget. Microbial denitrification is a large source of N 2 O emissions in terrestrial and aquatic ecosystems. Most microbial denitrification is a form of anaerobic respiration in which nitrate (NO 3 − , the dominant form of inorganic N) is converted to dinitrogen (N 2 ) and N 2 O gases ( 5 ). The proportion of denitrified NO 3 − that is converted to N 2 O rather than N 2 (hereafter referred to as the N 2 O yield and expressed as the mole ratio) partially controls how much N 2 O is produced via denitrification ( 6 ), but few studies provide information on the N 2 O yield in streams and rivers because of the difficulty of measuring N 2 and N 2 O production in these systems. Here we report rates of N 2 and N 2 O production via denitrification measured using whole-stream 15 NO 3 − -tracer experiments in 72 headwater streams draining different land-use types across the United States. This project, known as the second Lotic Intersite Nitrogen eXperiment (LINX II), provides unique whole-system measurements of the N 2 O yield in streams. Although N 2 O emission rates have been reported for streams and rivers ( 7 , 8 ), the N 2 O yield has been studied mostly in lentic freshwater and marine ecosystems, where it generally ranges between 0.1 and 1.0%, although yields as high as 6% have been observed ( 9 ). These N 2 O yields are low compared with observations in soils (0–100%) ( 10 ), which may be a result of the relatively lower oxygen (O 2 ) availability in the sediments of lakes and estuaries. However, dissolved O 2 in headwater streams is commonly near atmospheric equilibrium and benthic algal biofilms can produce O 2 at the sediment–water interface, resulting in strong redox gradients more akin to those in partially wetted soils. Thus, streams may have variable and often high N 2 O yields, similar to those in soils ( 11 ). The N 2 O yield in headwater streams is of particular interest because much of the NO 3 − input to rivers is derived from groundwater upwelling into headwater streams. Furthermore, headwater streams compose the majority of stream length within a drainage network and have high ratios of bioreactive benthic surface area to water volume ( 12 ).

Proceedings of the National Academy of Sciences of↗
USGS1997

Pesticides in ground water: distribution, trends, and governing factors

A comprehensive review of published information on the distribution and behavior of pesticides and their transformation products in ground water indicates that pesticides from every chemical class have been detected in ground waters of the United States. Many of these compounds are commonly present at low concentrations in ground water beneath agricultural land. Little information is available on their occurrence beneath non-agricultural land, although the intensity of their use in such areas (on lawns, golf courses, rights of way, timberlands, etc.) is often comparable to, or greater than agricultural use. Information on pesticides in ground water is not sufficient to provide either a statistically representative view of pesticide occurrence in ground water across the United States, or an indication of long-term trends or changes in the severity or extent of this contamination over the past three decades. This is largely due to wide variations in analytical detection limits, well selection procedures, and other design features among studies conducted in different areas or at different times. Past approaches have not been well suited for distinguishing "point source" from "nonpoint source" pesticide contamination. Among the variety of natural and anthropogenic factors examined, those that appear to be most strongly associated with the intensity of pesticide contamination of ground water are the depth, construction and age of the sampled wells, the amount of recharge (by precipitation or irrigation), and the depth of tillage. Approaches commonly employed for predicting pesticide distributions in the subsurface--including computer simulations, indicator solutes (e.g., nitrate or tritium), and ground-water vulnerability assessments--generally provide unreliable predictions of pesticide occurrence in ground water. Such difficulties may arise largely from a general failure to account for the preferential transport of pesticides in the subsurface. Significant improvements in understanding and predicting the occurrence and fate of pesticides in ground water are likely to depend on: (1) greater coordination of ground-water sampling across the nation to ensure consistency of study design, and thus comparability of results; (2) more extensive analyses for pesticide transformation products during ground-water monitoring studies; (3) substantially enhanced communication among investigators conducting laboratory experiments, small-scale field studies and large-scale monitoring studies; and (4) more routine testing of predictions of pesticide behavior and ground-water vulnerability against actual field observations of pesticide occurrence in ground water

Book↗
USGS2000

Hydrogeology of the regional aquifer near Flagstaff, Arizona, 1994-97

Sandstones, siltstones, and limestones that are Pennsylvanian to Permian in age underlie the southern part of the Colorado Plateau near Flagstaff, Arizona, and contain a complex regional aquifer that has become increasingly important as a source of water for domestic, municipal, and recreational uses. Ground-water flow in the regional aquifer is poorly understood in this area because (1) depth of the aquifer limits exploratory drilling and testing and (2) the geologic structure increases the complexity of the aquifer characteristics and the ground-water flow system. Four methods were used to improve the understanding of the hydrogeology of the regional aquifer near Flagstaff. • Remote-sensing techniques and geologic mapping provided data to identify many structural features that indicate a more complex structural environment and history than previously realized. • Data from surface-geophysical techniques that included ground-penetrating radar, seismic reflection and seismic refraction, and square-array resistivity, verified that some of the geologic structures expressed at land surface propagate deep into the subsurface and through the principal water-bearing zones of the regional aquifer at near-vertical angles. • A well and spring inventory, borehole-geophysical methods, and well and aquifer tests provided additional information relating aquifer and ground-water flow characteristics to geologic structure. • Water-chemistry data, which included major ion, nutrient, trace-element, and radioactive and stable-isotope analyses, provided an independent means of verifying the hydrogeologic characteristics of the aquifer and were used to determine recharge and discharge areas, groundwater movement, and ground-water age. Ground-water recharge occurs throughout the area but is greatest at higher altitudes where precipitation is greater and in areas where heavily fractured rock units of the aquifer are exposed. The estimated annual average recharge to the regional aquifer in the study area is about 290,000 acre-feet. Ground water flows laterally and vertically through pore spaces in the rock and along faults and other fractures from high-altitude areas in the southern part of the study area to regional drains north of the study area along the Little Colorado and Colorado Rivers, and to drains south of the study area along Oak Creek and the Verde Valley. Ground-water discharge in these areas—about 400,000 acre-feet per year—exceeds the annual recharge to the aquifer in the Flagstaff area, but ground water from areas outside the study area contributes to this discharge as well. The saturated thickness of the regional aquifer averages about 1,200 feet, and the amount of water in storage could be as much as 4,800,000 acrefeet, or about 10 percent of the total volume of the aquifer. The quality of water in the regional aquifer in terms of dissolved-solids concentrations is good for most uses throughout the area. Dissolvedsolids concentrations generally are less than 500 milligrams per liter. Water in the regional aquifer is primarily a calcium magnesium bicarbonate type. In some areas near the Rio de Flag, the water has significant nitrate and chloride components, which indicate direct recharge in these areas from the Rio de Flag. Oxygen and deuterium data indicate a common recharge source for water in the aquifer and that some sites receive recharge from surface waters where evaporation has occurred. Estimated carbon-14 ages and tritium activities indicate ground-water ages from less than 200 years in the Lake Mary area to more than 5,000 years in the Wupatki area. The regional aquifer is heterogeneous and anisotrophic and has a complex ground-water flow system. The most productive water-bearing material tends to be fine- to medium-grained sandstones, and ground-water flow and potential well yields are related to geologic structure. Fracturing associated with structural deformation increases recharge locally and also increases the potential for high well yields. Surface-geophysical techniques provided information on the orientation of high-angle, deep-seated structure in the saturated zone. Borehole-geophysical data identified horizontal to near-horizontal fractures as significant components of the fracture-flow system not apparent in the surface-geophysical data. Structural features that strike northwest appear to be areas that have the greatest potential for high well yields. A north-northeastward-striking structure may be just as promising, but additional data are needed to verify this relation.

Arizona↗
USGS2012

Characterization of the hydrologic resources of San Miguel County, New Mexico, and identification of hydrologic data gaps, 2011

The U.S. Geological Survey (USGS), in cooperation with San Miguel County, New Mexico, conducted a study to assess publicly available information regarding the hydrologic resources of San Miguel County and to identify data gaps in that information and hydrologic information that could aid in the management of available water resources. The USGS operates four continuous annual streamgages in San Miguel County. Monthly discharge at these streamgages is generally bimodally distributed, with most runoff corresponding to spring runoff and to summer monsoonal rains. Data compiled since 1951 on the geology and groundwater resources of San Miguel County are generally consistent with the original characterization of depth and availability of groundwater resources and of source aquifers. Subsequent exploratory drilling identified deep available groundwater in some locations. Most current (2011) development of groundwater resources is in western San Miguel County, particularly in the vicinity of El Creston hogback, the hogback ridge just west of Las Vegas, where USGS groundwater-monitoring wells indicate that groundwater levels are declining. Regarding future studies to address identified data gaps, the ability to evaluate and quantify surface-water resources, both as runoff and as potential groundwater recharge, could be enhanced by expanding the network of streamgages and groundwater-monitoring wells throughout the county. A series of seepage surveys along the lengths of the rivers could help to determine locations of surface-water losses to and gains from the local groundwater system and could help to quantify the component of streamflow attributable to irrigation return flow; associated synoptic water-quality sampling could help to identify potential effects to water quality attributable to irrigation return flow. Effects of groundwater withdrawals on streamflow could be assessed by constructing monitoring wells along transects between production wells and stream reaches of interest to monitor decline or recovery of the water table, to quantify the timing and extent of water-table response, and to identify the spatial extent of capture zones. Assessment of groundwater potential could be aided by a county-wide distribution of water-level information and by a series of maps of groundwater potential, compiled for each individual aquifer, including saline aquifers, for which the potential for municipal use through desalination could be explored. A county-wide geographic information system hydrologic geodatabase could provide a comprehensive picture of water use in San Miguel County and could be used by San Miguel County as a decision-support tool for future management decisions.

New Mexico↗
USGS2017

Comparing stream-specific to generalized temperature models to guide salmonid management in a changing climate

Global climate change is predicted to increase air and stream temperatures and alter thermal habitat suitability for growth and survival of coldwater fishes, including brook charr (Salvelinus fontinalis), brown trout (Salmo trutta), and rainbow trout (Oncorhynchus mykiss). In a changing climate, accurate stream temperature modeling is increasingly important for sustainable salmonid management throughout the world. However, finite resource availability (e.g. funding, personnel) drives a tradeoff between thermal model accuracy and efficiency (i.e. cost-effective applicability at management-relevant spatial extents). Using different projected climate change scenarios, we compared the accuracy and efficiency of stream-specific and generalized (i.e. region-specific) temperature models for coldwater salmonids within and outside the State of Michigan, USA, a region with long-term stream temperature data and productive coldwater fisheries. Projected stream temperature warming between 2016 and 2056 ranged from 0.1 to 3.8 °C in groundwater-dominated streams and 0.2–6.8 °C in surface-runoff dominated systems in the State of Michigan. Despite their generally lower accuracy in predicting exact stream temperatures, generalized models accurately projected salmonid thermal habitat suitability in 82% of groundwater-dominated streams, including those with brook charr (80% accuracy), brown trout (89% accuracy), and rainbow trout (75% accuracy). In contrast, generalized models predicted thermal habitat suitability in runoff-dominated streams with much lower accuracy (54%). These results suggest that, amidst climate change and constraints in resource availability, generalized models are appropriate to forecast thermal conditions in groundwater-dominated streams within and outside Michigan and inform regional-level salmonid management strategies that are practical for coldwater fisheries managers, policy makers, and the public. We recommend fisheries professionals reserve resource-intensive stream-specific models for runoff-dominated systems containing high-priority fisheries resources (e.g. trophy individuals, endangered species) that will be directly impacted by projected stream warming.

Michigan↗
USGS1988

Hydrogeologic framework of the Virginia coastal plain

This report defines the hydrogeologic framework of the Virginia Coastal Plain and is a product of a comprehensive regional study to define the geology, hydrology, and geochemistry of the northern Atlantic Coastal Plain aquifer system extending from North Carolina to Long Island, New York. The Virginia Coastal Plain consists of an eastward-thickening wedge of generally unconsolidated, interbedded sands and clays, ranging in age from Early Cretaceous to Holocene. These sediments range in thickness from more than 6,000 feet beneath the northeastern part of the Eastern Shore Peninsula to nearly 0 feet along the Fall Line. Eight confined aquifers, eight confining units, and an uppermost water table aquifer are delineated as the hydrogeologic framework of the Coastal Plain sediments in Virginia. The nine regional aquifers, from oldest to youngest, are lower, middle, and upper Potomac, Brightseat, Aquia, Chickahominy-Piney Point, St. Marys-Choptank, Yorktown-Eastover, and Columbia. The Brightseat is a newly identified and correlated aquifer of early Paleoceneage. This study is one of other, similar studies of the Coastal Plain areas in North Carolina, Maryland-Delaware, New Jersey, and Long Island, New York. These combined studies provide a system of hydrogeologic units that can be identified and correlated throughout the northern Atlantic Coastal Plain. Data for this study were collected and analyzed from October 1979 to May 1983. The nine aquifers and eight confining units are identified and delineated by use of geophysical logs, drillers' information, and stratigraphic and paleontologic data. By correlating geophysical logs with hydrologic, stratigraphic, and paleontologic data throughout the Coastal Plain, a comprehensive multilayered framework of aquifers and confining units, each with distinct lithologic properties, was developed. Cross sections show the stratigraphic relationships of aquifers and confining units in the hydrogeologic framework of the Virginia Coastal Plain. Maps show confining-unit thicknesses and altitudes of aquifer tops, provide the basis for assigning aquifers to screened intervals of observation and production wells, and are used for the development of a comprehensive observation-well network in the Virginia Coastal Plain.

Virginia↗
USGS2001

Mourning dove productivity in California during 1992-95: Was it sufficient to balance mortality?

Mourning dove ( Zenaida macroura ) populations have declined steadily in the western United States since 1966. We investigated the role of recruitment in this long-term problem by studying nesting ecology of mourning doves from March to September 1992-95, in the northern Central Valley, California, USA. We studied nesting doves in blue oak woodlands ( Quercus douglasii ), willow-cottonwood riparian habitats ( Salix spp., Populus fremontii ), and commercial walnut, prune, pistachio, and cherry orchards. We used 3,047 nests for our analyses. Doves initiated nests from 14 March to 28 August; nesting season lengths ranged from 105 to 158 days. Only 2-5% of nests remained active after 1 September each year, and latest dates that young fledged ranged from 28 August to 21 September. Mayfield estimates of nest success rates varied inconsistently among study areas; annual success rates ranged from 35-59% for incubation, 49-79% for brooding, and 22-45% for total. Akaike's Information Criteria (AIC) analysis showed that total nest success was higher during years with relatively warm-dry springs (March-May, 1992 and 1994 [35-45% success]) than years with relatively cool-wet springs (1993 and 1995 [22-37% success]). Additionally, AIC analysis showed that fledglings produced/pair and fledglings/nesting attempt were highest during the warm-dry years. Likewise, we recorded more total pairs, nests, and total fledglings, and longer nesting seasons during the warm-dry years. The lower limit of the 95% confidence interval for fledglings produced/pair for all years exceeded the value of 2.5 previously estimated with banding data from 1967-74 as the value required to maintain breeding populations in California. Thus, if our productivity estimates reflected the general population, and annual survival rates had not changed, recruitment should have been adequate to produce an increasing population. Since this was not occurring, managers should complement population surveys with annual banding and harvest surveys to enable thorough examination of the relationships among survival, productivity, and abundance.

California↗
USGS2016

Social-value maps for Arapaho, Roosevelt, Medicine Bow, Routt, and White River National Forests, Colorado and Wyoming

Executive Summary The continued pressures of population growth on the life-sustaining, economic, and cultural ecosystem services provided by our national forests, particularly those located near rapidly growing urban areas, present ongoing challenges to forest managers. Achieving an effective assessment of these ecosystem services includes a proper accounting of the ecological, economic, and social values attributable to them. However, assessments of ecosystem goods and services notably lack information describing the spatial distribution and relative intensity of social values—the perceived, nonmarket values derived particularly from cultural ecosystem services. A geographic information system (GIS) tool developed to fill this need, Social Values for Ecosystem Services (SolVES; http://solves.cr.usgs.gov ), now provides the capability to generate social-value maps at a range of spatial scales. This report presents some of the methods behind SolVES, procedures needed to apply the tool, the first formal map products resulting from its application at a regional scale, and a discussion of the management implications associated with this type of information. In this study, we use SolVES to identify the location and relative intensity of social values as derived from survey responses gathered from residents living in counties adjacent to Arapaho, Roosevelt, Medicine Bow, Routt, and White River National Forests. The results, presented as a series of social-value maps, represent the first publicly available spatial data on social-value intensity for the southern Rocky Mountain region. Our analysis identified high-value areas for social values including aesthetic, biodiversity, and life sustaining within wilderness areas. Other values, like recreation, show high-value areas both within wilderness and throughout the general forest areas, which can be attributed to people using the forests for a diverse set of recreational activities. The economic social-value type was lower within wilderness areas, which was an expected outcome because of the restrictions inside wilderness areas that preclude resource extraction, development, and motorized or mechanized recreation. Providing spatially explicit social-value information collected from residents in counties adjacent to these national forests can assist in facilitating the U.S. Department of Agriculture Forest Service’s Multiple-Use Sustained-Yield Act of 1960 (16 U.S.C. 528) note and the 2012 Forest Service Planning Rule (36 CFR Part 219), which encourage public participation in planning and management. By making these maps available to the public, we hope to encourage exploration of potential uses of these data for resource management and planning.

Colorado, Wyoming↗
USGS2019

Dissolved oxygen controls summer habitat of Clear Lake Hitch (Lavinia exilicauda chi), an imperilled potamodromous cyprinid

The Clear Lake Hitch is an imperiled minnow endemic to Clear Lake, Lake County, California, USA that is listed as threatened under the California Endangered Species Act (ESA) and is a candidate for listing under the United States ESA. It exhibits a potamodromous life cycle whereby adults, which reach up to 6+ years in age and over 350 mm in length, migrate into Clear Lake’s ephemeral tributaries briefly during spring to spawn. Conservation and management of Clear Lake Hitch is inhibited, in part, by a lack of information on the lacustrine distribution and habitat of non-breeding individuals within Clear Lake. To address this problem, we sampled Clear Lake Hitch with gill nets in a stratified random sampling design to determine the distribution and habitat associations in early summer 2017 and 2018. We identified abundance-habitat relationships for juvenile and adult Clear Lake Hitch using Bayesian zero-inflated negative binomial generalized linear mixed modeling. The results indicated that dissolved oxygen concentration was the most important habitat feature among those measured; both juvenile and adult Clear Lake Hitch were substantially more abundant in normoxic (> 2 mg l-1) than in hypoxic (< 2 mg l-1) habitat. Both life stages also exhibited weak positive relationships with chlorophyll fluorescence, suggesting that relatively productive habitats may support higher numbers of Clear Lake Hitch. Spatially, juveniles were most abundant in nearshore habitats while adults were ubiquitous, indicating an ontogentic habitat expansion that may be associated with a resource availability-predation risk tradeoff. Management actions undertaken to improve or alleviate water quality and hypoxia problems in Clear Lake would also improve Clear Lake Hitch habitat.

California↗
USGS2008

An enhanced global elevation model generalized from multiple higher resolution source datasets

Global digital elevation models are routinely used in a variety of earth science applications. GTOPO30, a widely used global elevation model produced by the U.S. Geological Survey, was produced in the mid-1990s from several regional sources of elevation information. Since the time GTOPO30 was developed, new and improved sources of elevation data have become available, and the U.S. Geological Survey and the National Geospatial-Intelligence Agency are collaborating on the development of a notably enhanced global elevation model that will replace GTOPO30 as the elevation dataset of choice for global and continental scale applications. The new model is being generated at three separate resolutions (horizontal post spacings) of 30 arc-seconds (about 1 kilometer), 15 arc-seconds (about 500 meters), and 7.5 arc-seconds (about 250 meters). An additional advantage of the new multiresolution global model over GTOPO30 is that seven new raster elevation products will be available at each resolution. The new elevation products are being produced using the following aggregation methods: minimum elevation, maximum elevation, mean elevation, median elevation, standard deviation of elevation, systematic subsample, and breakline emphasis. The primary source dataset for the new global model is the Shuttle Radar Topography Mission 1-arc-second data. When complete, the new global model will undergo a thorough accuracy assessment against reference geodetic control and a relative comparison against the existing GTOPO30 at the 30-arc-second resolution. Full documentation describing the input datasets, the processing, the characteristics of the new global model product layers, and the accuracy assessment results will be available to users. The development of the new global elevation model is in progress, with completion scheduled for mid-2009.

Conference Paper↗
USGS2006

The occurrence of volatile organic compounds in aquifers of the United States

The U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program recently completed a national assessment of volatile organic compounds (VOCs) in ground water (Zogorski and others, 2006). As part of this assessment, samples of ambient ground water collected from 3,498 wells during 1985-2002 were selected for characterizing the occurrence of 55 VOCs in 98 aquifer studies. The 55 VOCs were assigned to the following groups on the basis of their primary usage (or origin): (1) fumigants, (2) gasoline hydrocarbons, (3) gasoline oxygenates, (4) organic synthesis compounds, (5) refrigerants, (6) solvents, and (7) trihalo-methanes (chlorination by-products). The samples were collected throughout the conterminous United States as well as Alaska and Hawaii. The sampled wells had a variety of uses including domestic supply (61 percent), public supply (15 percent), monitoring (10 percent), other (13 percent), and unknown (1 percent). NAWQA aquifer studies are large-scale resource assessments of ground water that provide a general characterization of water-quality conditions in locally and regionally important aquifers or portions thereof. In general, the aquifers (or portions thereof) selected for study were some of the most intensively used aquifers for drinking water in greaterHawaiiOahuAlaskathe Nation. The 98 aquifer studies collectively provide an important national perspective on the current (1985-2002) extent of VOC contamination and regional patterns of VOC occurrence in ground water. More information about this national assessment of VOCs is available at a supporting Web site (http://water.usgs.gov/nawqa/vocs/national_assessment).

Scientific Investigations Map↗
USGS2018

A new Enceladus global control network, image mosaic, and updated pointing kernels from Cassini's thirteen-year mission

NASA's Cassini spacecraft spent 13 years exploring the Saturn system, including 23 targeted flybys of the small, geologically active moon Enceladus. These flybys provided a wealth of image data from Cassini's Imaging Science Subsystem. To improve the usability of the Enceladus data set, we created a new, global photogrammetric control network for Enceladus that enabled compilation of a versatile cartographic package to support geologic mapping and other investigations. The network used 586 images in four image filters with a pixel scale generally between 50 and 500 m per pixel and a phase angle less than 120° and consisted of 10,362 tie points and 173,704 individual image measures, averaging nearly 17 measures per tie point. Least squares bundle adjustment resulted in a root‐mean‐square residual of 0.45 pixel, corresponding to root‐mean‐square ground point uncertainties of 66, 51, and 46 m in latitude, longitude, and radius, respectively. Using our geodetic control network, we created new global image mosaics, coregistered flyby mosaics to support geologic mapping, and updated pointing kernels for every image used in the solution. These products, including the updated pointing kernels, are available to the community through NASA's Planetary Data System Imaging Annex. The bundle adjustment solution also yielded independently determined shape information, resulting in radii within the stated uncertainty of International Astronomical Union values. The challenges of the data set, and the technical methodology described here are applicable to bodies imaged during multiple flybys with variable viewing and illumination geometry, including other midsized satellites of Saturn, and the Europa Clipper mission.

Earth and Space Science↗
USGS1984

Movements of translocated wolves in Minnesota

From Feb. 1975-May 1978, 104 wolves ( Canis lupus ) captured at or near Minnesota farms where depredations on livestock had been reported were translocated northward and eastward for 50-317 km into extensive forests; 3 others were released westward. Nine wolves were translocated twice, and 1 three times. Information on movements was obtained by radiotracking 17 wolves and by recovery of 16 others. All radio-tagged wolves left the release areas; adults left quickly, but pups generally remained longer, behaved less decisively, and settled nearby temporarily. Wolves released together did not remain together. Initial travel of most radio-tagged adults was between south and west, the general direction to their original location. Final directions were primarily to the west and northwest, due in part to physiographic barriers. Eight adults homed, 1 twice, to capture areas that were < 64 km from release sites. Nonhoming wolves were radiotracked and/or recovered 32-351 km from their capture sites and 23-302 km from their release sites. Translocation was largely unsuccessful at keeping problem wolves out of lifestock production areas. The problem of initial travel away from release sites in wolf reintroductions probably could be minimized by transport and release of 6-9 mo. old wolves.

Minnesota↗
USGS1982

The Alaska Mineral Resource Assessment Program: Guide to information about the geology and mineral resources of the Ketchikan and Prince Rupert quadrangles, southeastern Alaska

The Ketchikan and Prince Rupert 1-degree by 2-degree quadrangles, which encompass about 16,000 km2 at the south tip of southeastern Alaska, have been investigated by integrated field and laboratory studies in the disciplines of geology, geochemistry, geophysics, and Landsat data interpretation to determine their mineral-resource potential. Mineral deposits in the study area have been mined or prospected intermittently since about 1900, and production of small tonnages of ores containing gold, silver, copper, lead, zinc, and tungsten has been recorded. Extensive exploration and development currently (1981) is underway at a molybdenum prospect about 65 km east of Ketchikan. Our mineral-resource assessment indicates that the area contains potentially significant amounts of those metallic commodities, as well as of molybdenum, iron, antimony, and barite. The results of these studies have been published in a folio of maps accompanied by descriptive texts, diagrams, tables, and pertinent references. The present report serves as a guide to these investigations, provides relevant background information, and integrates the component maps and reports. It also describes revisions to the geology based on studies completed since the folio was published and includes a list of specific and general references on the geology and mineral deposits of the study area.

Alaska↗
USGS2023

User’s Guide to planetary image analysis and geologic mapping in ArcGIS Pro

Geologic maps are valuable tools in planetary science. Though planetary geologic maps are similar to terrestrial (Earthbased) geologic maps, the nature of planetary exploration introduces unique challenges for geologic mappers. Terrestrial geologic mappers prepare products from field-based observation, often comparing or refining those with aerial and (or) orbital images. Planetary geologic mapping relies almost exclusively on remote observations, which are made by orbiting spacecraft. Therefore, with a few exceptions for locations with rovers, landers, or crewed surface missions, planetary geologic mappers are not able to observe their map area in detail or at smaller scales. As a result, they must interpret and describe their map features differently than those used in terrestrial geologic maps. For example, terrestrial geologic mappers commonly divide units by lithology (rock type) or grain size. However, planetary geologic mappers often do not have detailed enough information to know what type of rock or grain size is present, and instead must divide the planet’s surface into geologic units using differences in tone, color, and surface texture (at multiple scales). Cross-cutting relationships, where apparent, can provide excellent—and often crucial—observations for identifying and subdividing geologic units using orbital datasets. The process of creating planetary maps has evolved over time, from original hand-drawn maps created during the early 1800s through the late 1900s, to the fully digital products created today. Modern-day planetary geologic mapping uses Geographic Information Systems (GIS) software and tools to visualize data, delineate units and landforms, and accurately convey spatial relationships to a map user using cartographic features represented by points, lines, and polygons. This tutorial was written to familiarize both new and experienced planetary geologic mappers with ArcGIS Pro, a commonly used GIS software package developed by Esri. This tutorial introduces new planetary geologic mappers to fundamental concepts and best practices in planetary geologic mapping. For mappers with experience using ArcMap (a previous version of ArcGIS), this tutorial will help to familiarize users with new changes in layout and functionality, so current projects may be migrated into the ArcGIS Pro environment. No prior knowledge is required, although a general familiarity with geology, GIS, and planetary science is recommended. This tutorial includes links to helpful glossaries of common GIS terms and other GIS and planetary science resources in appendix 1. For additional information on planetary geologic mapping, see the U.S Geological Survey (USGS) Astrogeology NASA Planetary Geologic Mapping Program website and the Planetary Mapping Guidelines. Numerous ArcGIS tutorials are also available from Esri’s Tutorials page, through the Esri Academy catalog, and Esri’s ArcGIS Pro Resources page.

Techniques and Methods↗