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At least 1,351 records · Page 75Linked to original sources
USGS2014

A recording evaporimeter

The instrument herein described was originally designed and built to record the evaporation‐loss from a standard Weather Bureau pan for use in a study of the variation of flow in Santa Ana River. Valuable suggestions were made by various members of the Water Resources Branch of the Geological Survey in Southern California, and financial assistance for construction was given by F. C. Ebert and H. C. Troxell of the same organization. The typing of the paper and some of the drafting were done by Works Progress Administration help. The original instrument was damaged by flood‐waters in 1934, while in operation at Baldwin Park, California. It was then redesigned and constructed of stainless materials and installed on the campus of the San Bernardino Valley Junior College. The Weather Bureau pan was replaced by a thermally insulated pan. The damping unit was added at this time by the present writers. The evaporimeter was placed in regular operation on October 30, 1937, in a study of the relative magnitudes of the various energy‐components associated with solar and sky radiation and with evaporation from water‐surfaces, from damp soil, and from plants.

Eos, Transactions, American Geophysical Union↗
USGS2019

Capacity and area of Grand Lake O’ the Cherokees, northeastern Oklahoma, 2009

In February 2017, the Grand River Dam Authority filed to relicense the Pensacola Hydroelectric Project with the Federal Energy Regulatory Commission. The predominant feature of the Pensacola Hydroelectric Project is Pensacola Dam, which impounds Grand Lake O’ the Cherokees (locally called Grand Lake) in northeastern Oklahoma. Identification of information gaps and assessment of project effects on stakeholders are central aspects of the Federal Energy Regulatory Commission relicensing process. Due to the natural changes to the reservoir over time, new capacity and area tables are needed periodically. The most recent complete capacity and area table was produced in 1940. Capacity and area tables identify the relations between the elevation of the water surface and the volume of water that can be impounded at each water surface elevation. This report (1) presents an updated capacity and area table for Grand Lake O’ the Cherokees for 2009, (2) describes the methods used to calculate the updated capacity and area values presented in the table, and (3) compares the updated capacity table to historical capacity tables produced from a survey in 1940 and from a hydrographic survey of the lake by the Oklahoma Water Resources Board in 2009. The new capacity values computed for Grand Lake O’ the Cherokees indicate that capacity at conservation pool elevation has decreased about 157,000 acre-feet or 10 percent since 1940 and capacity at top of dam elevation has decreased about 200,000 acre-feet or 8 percent since 1940. This difference in the capacities could be attributed to the advancements of technologies; the techniques used for surveying lakes have changed from the 1940 survey to the 2009 survey. Another possible reason for loss in capacity could be as time progresses, lakes like Grand Lake O’ the Cherokees slowly impound sediment carried by the rivers that feed into the lakes, thus diminishing the amount of water that the lake holds. The most recent survey used measured water depths and Global Position System collected electronically, but the methods used to collect data in 1940 are unknown. Due to the advancement of technology, the 2009 survey is likely more precise than the 1940 survey.

Oklahoma↗
USGS2016

Mid-21st-century climate changes increase predicted fire occurrence and fire season length, Northern Rocky Mountains, United States

Climate changes are expected to increase fire frequency, fire season length, and cumulative area burned in the western United States. We focus on the potential impact of mid-21st-century climate changes on annual burn probability, fire season length, and large fire characteristics including number and size for a study area in the Northern Rocky Mountains. Although large fires are rare they account for most of the area burned in western North America, burn under extreme weather conditions, and exhibit behaviors that preclude methods of direct control. Allocation of resources, development of management plans, and assessment of fire effects on ecosystems all require an understanding of when and where fires are likely to burn, particularly under altered climate regimes that may increase large fire occurrence. We used the large fire simulation model FSim to model ignition, growth, and containment of wildfires under two climate scenarios: contemporary (based on instrumental weather) and mid-century (based on an ensemble average of global climate models driven by the A1B SRES emissions scenario). Modeled changes in fire patterns include increased annual burn probability, particularly in areas of the study region with relatively short contemporary fire return intervals; increased individual fire size and annual area burned; and fewer years without large fires. High fire danger days, represented by threshold values of Energy Release Component (ERC), are projected to increase in number, especially in spring and fall, lengthening the climatic fire season. For fire managers, ERC is an indicator of fire intensity potential and fire economics, with higher ERC thresholds often associated with larger, more expensive fires. Longer periods of elevated ERC may significantly increase the cost and complexity of fire management activities, requiring new strategies to maintain desired ecological conditions and limit fire risk. Increased fire activity (within the historical range of frequency and severity, and depending on the extent to which ecosystems are adapted) may maintain or restore ecosystem functionality; however, in areas that are highly departed from historical fire regimes or where there is disequilibrium between climate and vegetation, ecosystems may be rapidly and persistently altered by wildfires, especially those that burn under extreme conditions.

Idaho↗
USGS2007

Results from Coalbed Methane Drilling in Winn Parish, Louisiana

A coalbed methane (CBM) well in Winn Parish, Louisiana, named CZ Fee A No. 114, was drilled by Vintage Petroleum, Inc., in January 2004. The CZ Fee A No. 114 CBM well was drilled to a total depth of 3,114 ft and perforated at 2,730-2,734 ft in a Wilcox Group (Paleocene-Eocene) coal bed. Analytical data from the drilling project have been released by Vintage Petroleum, Inc., and by the current well operator, Hilcorp Energy Corporation (see Appendix) to the Louisiana Geological Survey (LGS) and the U.S. Geological Survey (USGS) for publication. General information about the CZ Fee A No. 114 CBM well is compiled in Table 1, and analytical data from the well are included in following sections. The CZ Fee A No. 114 well is located in eastern Winn Parish, approximately 30 mi east of where Wilcox Group strata crop out on the Sabine Uplift (fig. 1). In the CZ Fee A No. 114 well, lower Wilcox Paleocene coal beds targeted for CBM production occur at depths of 2,600-3,000 ft (fig. 2). Average monthly gas production for the reporting period August 1, 2004, through May 1, 2005, was 450 thousand cubic feet (Mcf) (Louisiana Department of Natural Resources, 2005).

Open-File Report↗
USGS2024

Skill assessment of a total water level and coastal change forecast during the landfall of a hurricane

The Total Water Level and Coastal Change Forecast (TWL&CC Forecast) provides coastal communities with 6-day notice of potential elevated water levels and coastal change (i.e., dune erosion, overwash, or inundation) on sandy beaches that threatens safety, infrastructure, or resources. This continuously operating model provides hourly information for select regions along U.S. Gulf of Mexico and Atlantic Ocean coastlines. The objective of this work is to assess the skill of forecasts during a period of elevated water levels along the coasts of North Carolina (NC) and South Carolina, USA caused by Hurricane Isaias in August 2020, using a combination of observations and model hindcasts. Water levels and waves were observed throughout the storm at three locations near Wrightsville Beach, NC, which provided information to assess forecast skill; a wave buoy offshore, a tide gage at a local pier, and a pressure sensor deployed at the pier. In addition to observations, the non-hydrostatic phase-resolving model SWASH (Simulating WAves till SHore) was forced with hourly wave energy spectra derived from a coupled Delft3D-SWAN simulation during the peak of Isaias, to complement observations by computing nearshore wave height and wave-induced setup and runup at the shoreline. During the storm peak, SWASH-simulated water levels at the sensor position were comparable to those at the maximum landward extent (bias = −0.05 m; gain = 0.26; r 2 = 0.99), suggesting that observations at the USGS sensor location were a useful proxy for total water level (TWL; sum of tide, surge and wave runup) at the shoreline that are predicted by the TWL&CC Forecast. The TWL forecast at Wrightsville Beach was consistent with observations from the USGS sensor (bias = −0.38 m and −0.74 m, scatter index = 0.22 and 0.28 for the two forecast model grids considered, respectively; weighted regression considering model uncertainty explained 95 percent of variability in observed TWL). Observed TWL was within the confidence interval of the TWL&CC Forecast for the 5 h at the storm peak. Forecast mean water levels (MWL; sum of tide, surge and wave setup) and tide gage observations were also consistent (bias = 0.07 m and 0.02 m for the forecast model grids; scatter index = 0.46; r 2 = 0.80). Forecast MWL at the storm peak was within 0.06 m of the observed MWL from the tide gage for both sites. In the region where Isaias made landfall, eight additional pressure sensors were compared to the peak TWL forecast (bias = 0.14 m; scatter index = 0.18). Forecast TWL explained 90 percent of observed variability in TWL when considering uncertainty of the forecast with a weighted regression. The results demonstrate that wave-driven water levels contributed a significant portion of the forecast TWL during Isaias (52 percent during the three peak hours of the storm), and that TWL were represented using the forecast model. Mean absolute error of the coastal change forecast and observed overwash is 0.4 and 0.14 for the two forecast model grids considered. The skill demonstrated by this computationally efficient method indicates that the forecasting system can provide fast and reliable predictions of TWL across hundreds of km of coastline at sub-km resolution, days to hours in advance of when storms threaten coastal regions.

Coastal Engineering↗
USGS2019

Examination of Bathymodiolus childressi nutritional sources, isotopic niches, and food-web linkages at two seeps in the US Atlantic margin using stable isotope analysis and mixing models

Chemosynthetic environments support distinct benthic communities capable of utilizing reduced chemical compounds for nutrition. Hundreds of methane seeps have been documented along the U.S. Atlantic margin (USAM), and detailed investigations at a few seeps have revealed distinct environments containing mussels, microbial mats, authigenic carbonates, and soft sediments. The dominant mussel, Bathymodiolus childressi , contains methanotrophic endosymbionts but is also capable of filter feeding, and stable isotope analysis (SIA) of mussel-shell periostracum suggests that these mussels are mixotrophic, assimilating multiple food resources. However, it is unknown whether mixotrophy is widespread or varies spatially and temporally. We used SIA (δ 13 C, δ 15 N, and δ 34 S) and an isotope mixing model (MixSIAR) to estimate resource contribution to B. childressi and characterize food webs at two seep sites (Baltimore Seep; 400 m and Norfolk Seep; 1500 m depths) along the USAM, and applied a linear mixed-effects model to explore the role of mussel population density and tissue type in influencing SIA variance. After controlling for location and temporal variation, isotopic variability was a function of proportion of live mussels present and tissue type. Isotopic differences were also spatially discrete, possibly reflecting variations in the underlying carbon source at the two sites. Low mussel δ 13 C values (∼−63‰) are consistent with a dependence on microbial methane. However, MixSIAR results revealed mixotrophy for mussels at both sites, implying a reliance on a mixture of methane and phytoplankton-derived particulate organic material. The mixing model results also reveal population density-driven patterns, suggesting that resource use is a function of live mussel abundance. Mussel isotopes differed by tissue type, with gill having the lowest δ 15 N values relative to muscle and mantle tissues. Based on mass balance equations, up to 79% of the dissolved inorganic carbon (DIC) of the pore fluids within the anaerobic oxidation of the methane zone is derived from methane and available to fuel upper slope deep-sea communities, such as fishes ( Dysommina rugosa and Symphurus nebulosus ), echinoderms ( Odontaster robustus , Echinus wallisi , and Gracilechinus affinis ), and shrimp, ( Alvinocaris markensis ). The presence of these seeps thereby increases the overall trophic and community diversity of the USAM continental slope. Given the presence of hundreds of seeps within the region, primary production at seeps may serve as an important, yet unquantified, energy source to the USAM deep-sea environment.

Delaware, Maryland, North Carolina, Virginia↗
USGS2015

Implications of the methodological choices for hydrologic portrayals of climate change over the contiguous United States: Statistically downscaled forcing data and hydrologic models

Continental-domain assessments of climate change impacts on water resources typically rely on statistically downscaled climate model outputs to force hydrologic models at a finer spatial resolution. This study examines the effects of four statistical downscaling methods [bias-corrected constructed analog (BCCA), bias-corrected spatial disaggregation applied at daily (BCSDd) and monthly scales (BCSDm), and asynchronous regression (AR)] on retrospective hydrologic simulations using three hydrologic models with their default parameters (the Community Land Model, version 4.0; the Variable Infiltration Capacity model, version 4.1.2; and the Precipitation–Runoff Modeling System, version 3.0.4) over the contiguous United States (CONUS). Biases of hydrologic simulations forced by statistically downscaled climate data relative to the simulation with observation-based gridded data are presented. Each statistical downscaling method produces different meteorological portrayals including precipitation amount, wet-day frequency, and the energy input (i.e., shortwave radiation), and their interplay affects estimations of precipitation partitioning between evapotranspiration and runoff, extreme runoff, and hydrologic states (i.e., snow and soil moisture). The analyses show that BCCA underestimates annual precipitation by as much as −250 mm, leading to unreasonable hydrologic portrayals over the CONUS for all models. Although the other three statistical downscaling methods produce a comparable precipitation bias ranging from −10 to 8 mm across the CONUS, BCSDd severely overestimates the wet-day fraction by up to 0.25, leading to different precipitation partitioning compared to the simulations with other downscaled data. Overall, the choice of downscaling method contributes to less spread in runoff estimates (by a factor of 1.5–3) than the choice of hydrologic model with use of the default parameters if BCCA is excluded.

Journal of Hydrometeorology↗
USGS2012

A spatial analysis of cultural ecosystem service valuation by regional stakeholders in Florida: a coastal application of the social values for ecosystem services (SolVES) tool

Livelihoods and lifestyles of people throughout the world depend on essential goods and services provided by marine and coastal ecosystems. However, as societal demand increases and available ocean and coastal space diminish, better methods are needed to spatially and temporally allocate ocean and coastal activities such as shipping, energy production, tourism, and fishing. While economic valuation is an important mechanism for doing so, cultural ecosystem services often do not lend themselves to this method. Researchers from the U.S. Geological Survey are working collaboratively with the Florida Sea Grant College Program to map nonmonetary values of cultural ecosystem services for a pilot area (Sarasota Bay) in the Gulf of Mexico. The research seeks to close knowledge gaps about the attitudes and perceptions, or nonmonetary values, held by coastal residents toward cultural ecosystem services, and to adapt related, terrestrial-based research methods to a coastal setting. A critical goal is to integrate research results with coastal and marine spatial planning applications, thus making them relevant to coastal planners and managers in their daily efforts to sustainably manage coastal resources. Using information about the attitudes and preferences of people toward places and uses in the landscape, collected from value and preference surveys, the USGS SolVES 2.0 tool will provide quantitative models to relate social values, or perceived nonmonetary values, assigned to locations by survey respondents with the underlying environmental characteristics of those same locations. Project results will increase scientific and geographic knowledge of how Sarasota Bay residents value their area’s cultural ecosystem services.

Florida↗
USGS1998

Effect of activities at the Idaho National Engineering and Environmental Laboratory on the water quality of the Snake River Plain aquifer in the Magic Valley study

Radiochemical and chemical constituents in wastewater generated at facilities of the Idaho National Engineering and Environmental Laboratory (INEEL) (figure 1) have been discharged to waste-disposal ponds and wells since the early 1950 s. Public concern has been expressed that some of these constituents could migrate through the Snake River Plain aquifer to the Snake River in the Twin Falls-Hagerman area Because of these concerns the U.S. Department of Energy (DOE) requested that the U.S. Geological Survey (USGS) conduct three studies to gain a greater understanding of the chemical quality of water in the aquifer. One study described a one-time sampling effort for radionuclides, trace elements, and organic compounds in the eastern part of the A&B Irrigation District in Minidoka County (Mann and Knobel, 1990). Another ongoing study involves sampling for tritium from 19 springs on the north side of the Snake River in the Twin Falls-Hagerman area (Mann, 1989; Mann and Low, 1994). A third study an ongoing annual sampling effort in the area between the southern boundary of the INEEL and Hagerman (figure 1) (hereafter referred to as the Magic Valley study area), is being conducted with the Idaho Department of Water Resources in cooperation with the DOE. Data for a variety of radiochemical and chemical constituents from this study have been published by Wegner and Campbell (1991); Bartholomay, Edwards, and Campbell (1992, 1993, 1994a, 1994b); and Bartholomay, Williams, and Campbell (1995, 1996, 1997b). Data discussed in this fact sheet were taken from these reports. An evaluation of data collected during the first four years of this study (Bartholomay Williams, and Campbell, 1997a) showed no pattern of water-quality change for radionuclide data as concentrations randomly increased or decreased. The inorganic constituent data showed no statistical change between sample rounds.

Idaho↗
USGS2016

Does resolution of flow field observation influence apparent habitat use and energy expenditure in juvenile coho salmon?

This study investigated how the resolution of observation influences interpretation of how fish, juvenile Coho Salmon ( Oncorhynchus kisutch ), exploit the hydraulic environment in streams. Our objectives were to evaluate how spatial resolution of the flow field observation influenced: (1) the velocities considered to be representative of habitat units; (2) patterns of use of the hydraulic environment by fish; and (3) estimates of energy expenditure. We addressed these objectives using observations within a 1:1 scale physical model of a full-channel log jam in an outdoor experimental stream. Velocities were measured with Acoustic Doppler Velocimetry at a 10 cm grid spacing, whereas fish locations and tailbeat frequencies were documented over time using underwater videogrammetry. Results highlighted that resolution of observation did impact perceived habitat use and energy expenditure, as did the location of measurement within habitat units and the use of averaging to summarize velocities within a habitat unit. In this experiment, the range of velocities and energy expenditure estimates increased with coarsening resolution (grid spacing from 10 to 100 cm), reducing the likelihood of measuring the velocities locally experienced by fish. In addition, the coarser resolutions contributed to fish appearing to select velocities that were higher than what was measured at finer resolutions. These findings indicate the need for careful attention to and communication of resolution of observation in investigating the hydraulic environment and in determining the habitat needs and bioenergetics of aquatic biota.

Water Resources Research↗
USGS2021

Cooperative Fish and Wildlife Research Units program—2020 research abstracts

The U.S. Geological Survey (USGS) serves as the research arm of the U.S. Department of the Interior and has established a series of strategic goals that focus its efforts on serving the American people. Within the USGS, the Ecosystems Mission Area is responsible for conducting and sponsoring research that addresses the following thematic objectives under the overarching strategic goal of “Science that Supports Our Resources in Wild and Urban Spaces, and the Landscapes In-Between”: Science supporting a legacy of sustainable fish and wildlife, Social science and human components in land, water, and wildlife conservation, Trusted science supporting hard decisions on at-risk species, Science to battle costly biological threats, Providing science for managing risks and responding to extreme events, Science for preservation and restoration of iconic landscapes, and Science to support adaptation and address impacts of climate and land change. This report provides abstracts of most of the ongoing and recently completed research investigations of the USGS Cooperative Fish and Wildlife Research Units program. The report is organized by the following major science themes that contribute to the objectives of the USGS: Advanced Technologies Climate Science Decision Science Ecological Flows Ecosystem Services Energy Fish and Wildlife Health and Disease Human Dimensions Invasive Species Landscape Ecology Species and Habitat Management Species of Greatest Conservation Need Threatened and Endangered Species

Circular↗
USGS1962

Ground-water investigations of the Project Gnome area, Eddy and Lea Counties, New Mexico

The U.S. Atomic Energy Commission, through the Office of Test Operations, Albuquerque Operations Office, plans to detonate a nuclear device in a massive salt bed 1,200 feet beneath the land surface. The project, known as Project Gnome, is an element of the Plowshare program--a study of peacetime applications of nuclear fission. The location of the proposed underground shot is in a sparsely-populated area in southeastern Eddy County, N. Mex., east of the Pecos River and about 25 miles southeast of the city of Carlsbad. The area is arid to Semiarid and ground water is a vital factor in the economic utilization of the land, which is primarily used for stock raising. An investigation of the Project Gnome site and surrounding area for the purposes of evaluating the ground-water resources and the possible effect upon them from the detonation of the nuclear shot was desired by the Commission. This report describes work done by the U.S. Geological Survey on behalf of the Commission and presents results of the investigation of the ground-water resources and geology of the area. The most intensive investigations were made within a 15-mile radius of the site of Project Gnome and mainly on the east side of the Pecos River. The total area of study of over 1,200 square miles includes parts of Eddy and Lea Counties, N. Mex. The Project Gnome site is in the sedimentary Delaware Basin. It is underlain by about 18,000 feet of sedimentary rocks ranging in age from Ordovician to Recent. Upper Permian evaporitic rocks, which contain the principal source of potash available in the United States, are worked in nearby mines. The potash minerals are found in a massive salt bed about 1,400 feet thick in the Salado Formation of Permian age. The land surface of the area is covered mostly by a wind-blown sand and caliche; however, rocks of the Rustler Formation of Permian age and younger rocks of Permian, Triassic, Pleistocene(?) and Recent age crop out at several localities. Solution by ground water of salt at the top of the Salado Formation and of anhydrite within the Rustler Formation has removed thick sections of these rocks. A subsequent lowering of the land surface and differential collapse of the Rustler has formed many sinkholes and has created a karst topography over much of the western part of the area. Ground water is obtained from rocks of Permian, Triassic, Tertiary, and Quaternary age in the general region. However, the only aquifer at the Gnome site is the Culebra Dolomite Member of the Rustler Formation of Permian age. The aquifer is about 500 feet beneath the surface at the site and is about 30 feet thick. An aquifer, immediately above the top of the salt, contains a brine solution in Nash Draw, a few miles west of the Gnome site. This aquifer discharges into the Pecos River and is a major source of contamination of the river water. No potable water is known to be present in the area below the top of the salt of the Salado Formation. The ground water in the area is generally under artesian pressure. The general direction of ground-water movement is toward the Pecos River both east and west of the river. At the Gnome site the artesian head of the water in the Culebra Dolomite Member is about 7.5 feet. The water moves westward through the aquifer at a rate of about ? foot per day. The most widespread utilization of ground water east of the river is for stock use. Irrigation usage west of the Pecos River accounts for the largest withdrawal of water. Wells range in depth from a few tens of feet to nearly 800 feet. Water levels range from a few feet to about 500 feet below the surface. A test well at the Gnome site drawing water from the Culebra Dolomite Member was pumped at a rate of 100 gpm (gallons per minute); however, most wells east of the river yield only a few gpm. Irrigation wells west of the river yield as much as 3,500 gpm. Most of the water in the area is highly mineralized and is suitable only for use by livest

Open-File Report↗
USGS2009

Coal-to-liquids: Potential impact on U.S. coal reserves

The production of liquid fuels from coal will very likely become an important part of the hydrocarbon energy mix of the future, provided that technical and environmental obstacles are overcome economically. The coal industry should be able to handle a coal-to-liquids (CTL) industry of modest size, using 60-70 million short tons or 54-64 million metric tonnes of coal per annum, without premature depletion of the country's coal reserves. However, attempts to use CTL technology to replace all petroleum imports would deplete the nation's coal reserves by the end of the century. ?? 2009 U.S. Government.

Natural Resources Research↗
USGS2018

Summary of wildlife-related research on the coastal plain of the Arctic National Wildlife Refuge, Alaska, 2002–17

We summarize recent (2002–17) publicly available information from studies within the 1002 Area of the Arctic National Wildlife Refuge as well as terrestrial and coastal ecosystems elsewhere on the Arctic Coastal Plain that are relevant to the 1002 Area. This report provides an update on earlier research summaries on caribou (Rangifer tarandus), forage quality and quantity, polar bears (Ursus maritimus), muskoxen (Ovibos moschatus), and snow geese (Chen caerulescens). We also provide information on new research related to climate, migratory birds, permafrost, coastal erosion, coastal lagoons, fish, water resources, and potential effects of industrial disturbance on wildlife. From this literature review, we noted evidence for change in the status of some wildlife and their habitats, and the lack of change for others. In the 1002 Area, muskox numbers have decreased and the Porcupine Caribou Herd has exhibited variation in use of the area during the calving season. Polar bears are now more common on shore in summer and fall because of declines in sea ice in the Beaufort Sea. In a study spanning 25 years, there were no significant changes in vegetation quality and quantity, soil conditions, or permafrost thaw in the coastal plain of the 1002 Area. Based on studies from the central Arctic Coastal Plain, there are persistent and emerging uncertainties about the long-term effects of energy development for caribou. In contrast, recent studies that examined direct and indirect effects of industrial activities and infrastructure on birds in the central Arctic Coastal Plain found little effect for the species and disturbances examined, except for the possibility of increased predator activity near human developments.

Alaska↗
USGS1996

Evapotranspiration from successional vegetation in a deforested area of the Lake Wales Ridge, Florida

The suitability of three evapotranspiration models (Penman-Monteith, Penman, and a modified Priestley-Taylor) was evaluated at a site of successional vegetation in a deforested area of the Lake Wales Ridge, Florida. Eddy correlation measurements of evapotranspiration made during 22 approximately 1-day periods at a temporal resolution of 20 minutes from September 1993 to August 1994 were used to calibrate the evapotranspiration models. Three variants of the eddy correlation method that ascribe measurement error to three different sources were considered in the analysis. The Penman-Monteith and modified Priestley- Taylor models were successful in approximating measured 20-minute values of evapotranspiration (r 2 ≥0.918). The most successful approaches were the modified Priestley-Taylor model (r 2 =0.972) and a nontraditional and simplified form of the Penman-Monteith model (r 2 =0.967). The Penman approach was unsuccessful as a predictor of evapotranspiration. The evapotranspiration models were used to estimate evapotranspiration between measurements. When evapotranspiration values measured with a Bowen ratio variant of the eddy correlation method were used for model calibration, estimated daily evapotranspiration rates varied seasonally ranging from 0.2 millimeters per day (0.008 inch per day) in late December 1993 to 5 millimeter per day (0.2 inch per day) in mid-July 1994. Annual evapotranspiration (September 15, 1993, to September 15, 1994) was estimated to be about 680 millimeters (27 inches). Evapotranspiration models calibrated to the standard eddy correlation method and to an energy-balance residual variant provided estimates of annual evapotranspiration that were about 10 per cent lower and higher, respectively. These data indicate that of the 1,320 millimeters (52 inches) of precipitation during the 1-year period, about 570 to 700 millimeters (22 to 28 inches) recharged the surficial aquifer. Evapotranspiration at this study site probably defines the lower limit of evapotranspiration from vegetated surfaces in central Florida because of the shallow-rooted plants, rapidly-drained soils, and relatively deepwater table.

Florida↗
USGS2009

Diets of aquatic birds reflect changes in the Lake Huron ecosystem

Human activities have affected the Lake Huron ecosystem, in part, through alterations in the structure and function of its food webs. Insights into the nature of food web change and its ecological ramifications can be obtained through the monitoring of high trophic level predators such as aquatic birds. Often, food web change involves alterations in the relative abundance of constituent species and/or the introduction of new species (exotic invaders). Diet composition of aquatic birds is influenced, in part, by relative prey availability and therefore is a sensitive measure of food web structure. Using bird diet data to make inferences regarding food web change requires consistent measures of diet composition through time. This can be accomplished by measuring stable chemical and/or biochemical “ecological tracers” in archived avian samples. Such tracers provide insights into pathways of energy and nutrient transfer. In this study, we examine the utility of two groups of naturally-occurring intrinsic tracers (stable isotopes and fatty acids) to provide such information in a predatory seabird, the herring gull ( Larus argentatus ). Retrospective stable nitrogen and carbon isotope analysis of archived herring gull eggs identified declines in gull trophic position and shifts in food sources in Lake Huron over the last 25 years and changes in gull diet composition were inferred from egg fatty acid patterns. These independent groups of ecological tracers provided corroborating evidence of dietary change in this high trophic level predator. Gull dietary shifts were related to declines in prey fish abundance which suggests large-scale alterations to the Lake Huron ecosystem. Dietary shifts in herring gulls may be contributing to reductions in resources available for egg formation. Further research is required to evaluate how changes in resource availability may affect population sustainability in herring gulls and other waterbird species. Long-term biological monitoring programs are required to identify ecosystem change and evaluate its ecological significance.

Lake Huron↗
USGS1997

Evaluation of agricultural best-management practices in the Conestoga River headwaters, Pennsylvania: Effects of pipe-outlet terracing on quantity and quality of surface runoff and ground water in a small carbonate-rock basin near Churchtown, Pennsylvania, 1983-89

Terracing effects on surface-runoff and ground- water quantity and quality were investigated by the U.S. Geological Survey, in cooperation with Pennsylvania Department of Environmental Resources, during 1983-89 at a 23.1-acre agricultural site in Lancaster County, Pa., as part of the 1982 Rural Clean Water Program. The site, underlain by carbonate rock, was primarily corn and alfalfa fields; the median slope was 6 percent.Normal precipitation is about 42 inches per year. Average annual runoff was 11 percent and ground- water recharge was 37 percent of precipitation.Runoff quantity, suspended-sediment, and nutrient data, ground-water level and nutrient data, and precipitation-quantity data were collected for 21 months prior to, and 58 months after, pipe-outlet terrace construction. Data were analyzed by use of graphical, regression, covariate, cluster, Mann- Whitney Rank Sum test, and double-mass curvetechniques. Terracing changed runoff characteristics. Storm characteristics were similar throughout the study period. However, after terracing, storms producing less than 0.4 inch of precipitation rarely produced runoff. Total-storm discharge as a function of precipitation did not change significantly throughout the range of runoff-producing storms after terracing. Multiple-discharge peaks on hydrographs before terracing did not occur after terracing when hydrographs reflected the stepwisedraining of each terrace through the pipe outlet. After an initial 2-year period of terrace stabilization, suspended-sediment yield in runoff decreased significantly as a function of runoff. This result was expected because terracing decreased runoff energy, and because terrace ponding allowed time for sediment redeposition. Nitrate plus nitrite yields increased proportionally throughout the range of runoff during the post-terracing period relative to the pre- terracing period. After terracing, a combination of increased soil contact time and increased nitrification caused by wetter soils is believed to have increased nitrate concentrations in runoff. No significant change was found in yields of total nitrogen, ammonia plus organic nitrogen, or total phosphorus relative to runoff before and after terracing. Limited data suggest that fine-sediment particles (less than 0.62 micrometers in diameter), which continued to be discharged from the site, transported most of the phosphorus. Terracing did not significantly change the quantity of recharge to the carbonate aquifer. The mean annual water-table altitude did not change after terracing. Nitrate concentrations of ground water increased significantly at four of the site wells after terracing, probably because of increased contact time of the recharge with nutrient-rich soils in ponded terrace water. Qualitative evidence indicates that large decreases in nutrient requirements and nitrogen applications because of a crop change from corn to alfalfa upgradient of two site wells resulted in either no detectable change or a significant decrease in nitrate concentrations of ground water after terracing.

Pennsylvania↗
USGS1982

Reconnaissance geologic map and mineral resource potential of the Gearhart Mountain Wilderness and Roadless Area (6225), Lake and Klamath counties, Oregon

The Gearhart Mountain Wilderness, Lake and Klamath Counties, Oreg., is devoid of mines and mineral prospects and there are no known mining claims within the area. Furthermore, the results of this mineral appraisal indicate that there is little likelihood that commercial deposits of metallic minerals will be found in the area. Commercial uranium deposits, like those at the White King and Lucky Lass mines about 16 mi (~25 km) to the southeast of the wilderness, and deposits of mercury, like those south-southeast of the wilderness, are not likely to be found within the wilderness, even though all of these areas are characterized by middle and late Cenozoic intrusive and extrusive volcanic rocks. Rock of low commercial value for construction purposes is present, but better and more accessible deposits are present in adjacent regions. There is no evidence to indicate that mineral fuels are present in the area. Higher than normal heat floe characterizes the region containing Gerheart Mountain, indicating that it may have some, as yet undefined, potential for the development of geothermal energy. Data are not available to determine whether this higher than normal heat flow is meaningful in terms of a potential energy source or as a guide to possible future exploration; lack of thermal springs or other evidence of localized geothermal anomalies within the Gerhart Mountain suggest, however, that the potential for the development of geothermal energy is probably low.

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