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At least 595 records · Page 33Linked to original sources
USGS2024

Coldwater fish in wadeable streams

Although we are consistent with the past edition of this volume regarding standard sampling techniques for wadeable, coldwater streams, this edition reflects recent literature, advances in calibrating numbers, and obtaining lengths of fish collected and provides additional clarity regarding effort. We also specify a minimum of two netters and one electrofisher operator for backpack electrofishing to allow capture of fish that “roll” downstream without surfacing (e.g., fish like sculpins, which lack swim bladders); however, as in the past edition, a minimum of one netter and one operator may be used on studies focused on fish with swim bladders, like salmonids (salmons and trouts). Finally, this chapter mentions specifically what factors should lead to standard adjustments to techniques to account for the range of habitat features typically encountered in headwater streams. Small, wadeable streams comprise most habitats available to fish in fluvial networks. Wadeable streams are generally less than 1 m deep, and fish can be sampled without the use of float craft. Cold waters are generally defined as having mean 7-d summer maximum water temperatures less than 20°C, providing habitat for coldwater fishes. Fish fauna of small, coldwater North American streams typically include salmonids, sculpins, minnows, sticklebacks, suckers, or lampreys (Hocutt and Wiley 1986). Standard sampling protocols provided herein apply most readily to salmonids because of their sport and commercial values (Johnson et al. 2007). Salmonids also have cultural values, are well studied and widely distributed, and act as predators, competitors, and prey (Lee et al. 1997). However, many of these methods can also be applied effectively to sample nonsalmonids. As interest in nonsalmonid species grows, further development and investigation of sampling methods for a broader diversity of species is expected (see section 8.5).

Book chapter↗
USGS2019

Characterization of hydrology and sediment transport following drought and wildfire in Cache Creek, California

The worst drought in California in over 1,200 years occurred between 2012-2017 (Griffin, 2014), depleting surface water and groundwater supply and drying out the soils past wilting point. In the summer of 2015, the Jerusalem and Rocky fires burned roughly 40,000 acres within the Cache Creek watershed. To fully characterize the post-fire effects in the Cache Creek watershed, an hourly model of streamflow and sediment transport was developed using the Hydrological Simulation Program – FORTRAN (HSPF). This model requires air temperature, precipitation, and potential evapotranspiration as climate inputs. Hourly station data are sparse in the area and may not capture the variability of elevation and local climatology patterns within the watershed. A technique used previously to spatially-interpolate daily-climate station data has improved the characterization of local and regional climate patterns on a daily scale in areas with sparse data (Flint et al., 2014). This technique was extended to hourly observed data to produce spatially-varying climate inputs for the Cache Creek hydrologic model to run as a continuous multi-year simulation with hourly time steps. Monthly PRISM grids were used in a two-step scaling method with climate Gradient and Inverse Distance Squared (GIDS) maps (Nalder and Wein, 1998) to develop daily grids, then the daily grids were used to scale hourly climate GIDS maps. This method captures the temporal variability at each climate station yet preserves the regional monthly spatial structure of the PRISM data. Hydrologic calibration used data from water year 2015, and validation used the same parameters for water year 2016. The model was run through water year 2017 to characterize the effects of wildfire on hydrology and sediment transport. For final simulations, the model was run at an hourly time step from June 2014 through September 2017 to ensure a model initiation period of 4 months prior to the target simulation period used for analysis. Sediment parameters were initially set using the existing Sacramento River Basin model for this sub-watershed area and then iteratively adjusted in the calibration process. To simulate a fire across the landscape, sediment parameters for water years 2016-17 were further modified for burned sub-basins to represent post-fire vegetation and soils in 2016, then partial recovery in 2017. Results were inconclusive for drought and wildfire effects on runoff. Modeled peak flows generally underpredicted observed peak flows; however, the modeled storm volumes were only slightly under or over the observed storm volumes. Sediment transport was sensitive to the watershed disturbances and R^2 values for daily mean suspended concentrations (SSC) and sediment discharge were 0.70 and 0.75, respectively. Simulated hourly values correlated less strongly with observed instantaneous SSC and sediment discharge (R^2 values of 0.56 and 0.46, respectively).

California↗
USGS1970

Perception via satellite

The earth resources observation satellite (EROS) program in the Department of the Interior is intended to gather and use data from satellites and aircraft on natural and man-made features of the earth's surface. Earth resources technology satellite will provide the EROS program with data for use in dealing with natural resource problems and understanding the interaction between man and the environment. Applications will include studies of tectonic features, hydrologic problems, location of fish schools, determination of the conditions of range land, mapping land use for urban planning, studies of erosion and change along coastlines and major streams, and inventories of land use and land forms. In addition, the ERTS data may be used for detecting forest and crop diseases and inventorying crops. The ERTS satellite will be in a polar, sun-synchronous orbit so that each point on the earth's surface will be sensed every 17 to 20 days, at the same time of day. Multispectral photography is being investigated for its usefulness in hydrology. Side-looking airborne radar has not yet been widely used in hydrologic studies, although it is an excellent tool for all-weather, day or night, coverage of large areas. Other techniques being investigated include passive microwave radiometry, ultraviolet and visible stimulated luminescence, and absorption spectroscopy.

Water Spectrum↗
USGS2021

The optical river bathymetry toolkit

Spatially distributed information on water depth is essential for many applications in river research and management and, under certain circumstances, can be inferred from remotely sensed data. Although fluvial remote sensing has emerged as a rapidly developing subdiscipline of the riverine sciences, more widespread adoption of these techniques has been hindered by a lack of accessible software. The Optical River Bathymetry Toolkit (ORByT) fills this void by providing a standalone package for mapping water depth from passive optical image data. The ORByT interface enables end users to import images and field‐based depth measurements, create and refine water masks, and perform spectrally based depth retrieval via an Optimal Band Ratio Analysis algorithm. The resulting bathymetric map can be exported as an image file, point cloud, and/or cross section; a thorough accuracy assessment also is incorporated into the workflow. In addition, image‐derived depth estimates can be subtracted from water surface elevations to obtain bed elevations suitable for input to a hydrodynamic model. Potential users of ORByT must bear in mind the inherent limitations of passive optical remote sensing: reliable bathymetry can only be inferred in clear‐flowing, shallow streams; this approach is not appropriate for more turbid, deeper rivers.

River Research and Applications↗
USGS1976

Flood-plain delineation for Cameron Run Basin, Fairfax County-Alexandria City, Virginia

Flood-Plain Delineation for Cameron Run Basin Water-surface profiles of the 25-, 50-, and 100-year recurrence interval discharges have been computed for all streams and reaches of channels in Fairfax County, Virginia, having a drainage area greater than 1 square mile except for Dogue Creek, Little Hunting Creek, and that part of Cameron Run above Lake Barcroft. Maps having a 2-foot contour interval and a horizontal scale of 1 inch equals 100 feet have been used for a base on which flood boundaries were delineated for 25-, 50-, and 100-year floods to be expected in each basin under ultimate development conditions. Included are techniques employed in computing discharges and profiles as well as the flood profiles and maps on which flood boundaries have been delineated for that part of Cameron Run basin below Lake Barcroft in both Fairfax County and the city of Alexandria.

Virginia↗
USGS2022

Salinification of coastal wetlands and freshwater management to support resilience

Climates are rapidly changing in wetland ecosystems around the world and historical land-use change is not always given enough consideration in climate adaptation discussions. Historical changes to hydrology and other key environments can exacerbate vegetation stress; e.g., recent drought and flood episodes are likely more extreme because of climate change. The contributions of global and regional changes that affect groundwater and surface water availability all need consideration in conservation planning including sea-level rise, coastal subsidence and compaction, fluid extraction, and floodplain reengineering. Where subsidence is not too extreme, healthy coastal vegetation often can keep ahead of sea-level rise by accreting elevation through sedimentary and/or biogenic processes. Better water conservation and minimum water delivery during drought may support foundational species and avoid wetland collapse. Local approaches have been developed to rewet inland floodplains decades after their reengineering for agricultural and urban development to support biodiversity in salinified coastal wetlands. The purpose of this paper is to describe inland wetland remediation techniques that may also be useful to increase freshwater delivery to coastal wetlands experiencing salinification. While some salinified coastal ecosystems may transition in the future, attempts can be made to remediate salinification related to historical land use in support of wetland conservation, health, and sustainability.

Ecosystem Health and Sustainability↗
USGS2019

Quantifying the eroded and deposited mass of mercury-contaminated sediment by using terrestrial laser scanning at the confluence of Humbug Creek and the South Yuba River, Nevada County, California, 2011–13

High-resolution, terrestrial laser scanning, also known as ground-based lidar (light detection and ranging), was used to quantify the volume of mercury-contaminated sediment eroded from an outcrop of historical placer-mining debris at the confluence of Humbug Creek and the South Yuba River in the Sierra Nevada foothills, about 17 kilometers northeast of Grass Valley, California, and delivered to a zone below an observed flood stage of the South Yuba River. Substantial quantities of mercury were used and lost to the environment from historical placer gold mining activities on the western slope of the Sierra Nevada, California, and recent studies have documented continued persistence of mercury and methylmercury concentrations in water, sediment, fish, and predatory invertebrates in the Yuba River drainage basin in relation to suspected mercury sources. To identify areas that have high levels of mercury contamination as possible remediation targets in the Yuba River drainage basin and other areas in the Sierra Nevada, the U.S. Geological Survey worked in cooperation with the Bureau of Land Management on this and other detailed studies. Malakoff Diggings, one of the largest hydraulic gold mines in the Sierra Nevada, is 3.5 kilometers north of the study site in the Humbug Creek subbasin. Terrestrial laser scanning was used to produce centimeter-scale, three-dimensional maps of the complex outcrop surface, which was composed of an upper erosional area (cliff and over-steepened slope) and a lower depositional area (colluvial slope). The outcrop could not be mapped non-destructively or in sufficient detail by traditional surveying techniques. The study site, which was approximately 70 meters long, 30 meters wide and 20 meters high, was surveyed four times in 2 years (December 15, 2011; October 25, 2012; January 4, 2013; and November 22, 2013) to determine volumetric differences in the upper erosional and lower depositional areas between surveys. Measured changes in volume for the upper erosional area and lower depositional area were multiplied by the corresponding sediment density so that a mass-balance relationship, between the eroded and deposited sediment during each period, could be used to estimate the amount of mercury-contaminated sediment that was transported to below the base of the colluvial slope, where it could be mobilized by the South Yuba River during a flood having a 5-to-10-year recurrence interval. On December 2, 2012, a flood of this estimated magnitude reached the base of the colluvial slope. Between the first and second surveys (December 15, 2011–October 25, 2012), an estimated mass of 18±9.2 kilograms of sediment was transported from steeper slopes to the gently sloping river bank below the base of the colluvial slope. Between the second and third surveys (October 25, 2012–January 4, 2013), an atmospheric river caused heavy precipitation at the study site during late November and early December 2012. This short-duration, high-intensity rain resulted in a large amount of erosion and deposition at the study site and also caused high streamflow (flood stage) in the South Yuba River. From October 2012 to January 2013, 51±31 kilograms of sediment was transported to below the base of the colluvial slope, that is, below the high-water mark of December 2, 2012. Between the third and fourth surveys (January 4, 2013–November 22, 2013), an additional 10±26 kilograms of sediment was transported to below the base of the colluvial slope. During the 24 months of the study, the total mass of sediment delivered below the base of the colluvial slope and the high-water mark of December 2, 2012, was 79±66 kilograms. In any given year there is a 10–20-percent chance (5-to-10-year recurrence interval) of a flood equal to or greater than that of the December 2, 2012, flood, which could transport mercury-contaminated sediment at the study site into the South Yuba River. Hydraulically modeled estimates of the South Yuba River stage during floods having a 50- and 100-year recurrence interval (2- and 1-percent annual exceedance probability, respectively) indicated that resulting river stages could be 2.2–3.0 meters above the base of the colluvial slope, or 2.2–3.0 meters above the high-water mark of December 2, 2012. Such high river stages would be likely to inundate the lower half of the colluvial slope and mobilize a substantial volume of mercury-contaminated sediment to downstream areas.

California↗
USGS2021

Evaluation of techniques for mitigating snowmelt infiltration-induced landsliding in a highway embankment

Infiltration-induced landslides threaten transportation infrastructure around the world, and impose both direct costs through repair and remediation work and indirect costs through lost economic activity. Therefore, finding the most cost-effective techniques to mitigate slope failures that can impact critical infrastructure links is desirable. The Straight Creek landslide, which affects a segment of Interstate 70 in Summit County, Colorado (USA), has experienced seasonal failure driven by rapid springtime snowmelt infiltration since the early 1970s, allowing changes in its stability to be studied. Past studies have established that seasonal failure is driven by pore-water pressure increase caused by the rapid infiltration of snowmelt and the hydraulic conductivity contrast between upper slope materials and the highway embankment. Two remediation designs have been applied to the site, including lightweight caissons beneath the highway surface in 2011 and 2012, and horizontal drains near the slide toe in 2012. The effects of the lightweight caissons and horizontal drains, as well as an alternative drain design that would extend into the hillslope above the highway embankment, are evaluated within a rigorous hydro-mechanical simulation framework along with a method to generate a field of local factor of safety. Model results show that the effect of the lightweight caissons on the factor of safety is no more than 1% during times of critical instability, as they do not affect the seasonal changes in hydrology that cause destabilizing decreases in effective stress along the failure surface. Horizontal drains are intended to reduce pore-water pressures, but the location of existing drains limit their efficacy due to the low hydraulic conductivity of subsurface materials underneath the highway. Model results indicate that these drains are only partially responsible for a reduction in movement rate since their installation, which is also due to lower annual cumulative snowmelt infiltration levels since 2012. Results also show that an alternative drain design could result in increased stability during critical periods by intercepting downslope subsurface flow before it arrives at the hydraulic conductivity contrast at the embankment.

Colorado↗
USGS1971

Techniques and equipment required for precise stream gaging in tide-affected fresh-water reaches of the Sacramento River, California

Current-meter measurements of high accuracy will be required for calibration of an acoustic flow-metering system proposed for installation in the Sacramento River at Chipps Island in California. This report presents an analysis of the problem of making continuous accurate current-meter measurements in this channel where the flow regime is changing constantly in response to tidal action. Gaging-system requirements are delineated, and a brief description is given of the several applicable techniques that have been developed by others. None of these techniques provides the accuracies required for the flowmeter calibration. A new system is described--one which has been assembled and tested in prototype and which will provide the matrix of data needed for accurate continuous current-meter measurements. Analysis of a large quantity of data on the velocity distribution in the channel of the Sacramento River at Chipps Island shows that adequate definition of the velocity can be made during the dominant flow periods--that is, at times other than slack-water periods--by use of current meters suspended at elevations 0.2 and 0.8 of the depth below the water surface. However, additional velocity surveys will be necessary to determine whether or not small systematic corrections need be applied during periods of rapidly changing flow. In the proposed system all gaged parameters, including velocities, depths, position in the stream, and related times, are monitored continuously as a boat moves across the river on the selected cross section. Data are recorded photographically and transferred later onto punchcards for computer processing. Computer programs have been written to permit computation of instantaneous discharges at any selected time interval throughout the period of the current meter measurement program. It is anticipated that current-meter traverses will be made at intervals of about one-half hour over periods of several days. Capability of performance for protracted periods was, consequently, one of the important elements in system design. Analysis of error sources in the proposed system indicates that errors in individual computed discharges can be kept smaller than 1.5 percent if the expected precision in all measured parameters is maintained.

Water Supply Paper↗
USGS2006

Multiple constraints on the age of a Pleistocene lava dam across the Little Colorado River at Grand Falls, Arizona

The Grand Falls basalt lava flow in northern Arizona was emplaced in late Pleistocene time. It flowed 10 km from its vent area to the Little Colorado River, where it cascaded into and filled a 65-m-deep canyon to form the Grand Falls lava dam. Lava continued ???25 km downstream and ???1 km onto the far rim beyond where the canyon was filled. Subsequent fluvial sedimentation filled the reservoir behind the dam, and eventually the river established a channel along the margin of the lava flow to the site where water falls back into the pre-eruption canyon. The ca. 150 ka age of the Grand Falls flow provided by whole-rock K-Ar analysis in the 1970s is inconsistent with the preservation of centimeter-scale flow-top features on the surface of the flow and the near absence of physical and chemical weathering on the flow downstream of the falls. The buried Little Colorado River channel and the present-day channel are at nearly the same elevation, indicating that very little, if any, regional downcutting has occurred since emplacement of the flow. Newly applied dating techniques better define the age of the lava dam. Infrared-stimulated luminescence dating of silty mudstone baked by the lava yielded an age of 19.6 ?? 1.2 ka. Samples from three noneroded or slightly eroded outcrops at the top of the lava flow yielded 3He cosmogenic ages of 16 ?? 1 ka, 17 ?? 1 ka, and 20 ?? 1 ka. A mean age of 8 ?? 19 ka was obtained from averaging four samples using the 40Ar/39Ar step-heating method. Finally, paleomagnetic directions in lava samples from two sites at Grand Falls and one at the vent area are nearly identical and match the curve of magnetic secular variation at ca. 15 ka, 19 ka, 23 ka, and 28 ka. We conclude that the Grand Falls flow was emplaced at ca. 20 ka. ?? 2006 Geological Society of America.

Geological Society of America Bulletin↗
USGS1982

Production and decomposition of forest litter fall on the Apalachicola River flood plain, Florida

Measurements of litter fall (leaves and other particulate organic material) and leaf decomposition were made on the bottom-land hardwood swamp of the Apalachicola River flood plain in 1979-80. Litter fall was collected monthly from nets located in 16 study plots. The plots represented five forest types in the swamp and levee areas of the Apalachicola River flood plain. Forty-three species of trees, vines, and other plants contributed to the total litter fall, but over 90 percent of the leaf material originated from 12 species. Nonleaf material comprised 42 percent of the total litter fall. Average litter fall was determined to be 800 grams per square meter per year, resulting in an annual deposition of 360,000 metric tons of organic material in the 454-square-kilometer flood plain. The levee communities have lower tree biomass but higher tree diversity than swamp communities. The levee vegetation, with lower tree biomass, produces slightly more litter fall per ground surface area than the swamp vegetation. The swamps are dominated by three genera: tupelo (Nyssa), cypress (Taxodium), and ash (Fraxinus). These genera account for over 50 percent of the total leaf fall in the flood plain but they are the least productive, on a weight-per-biomass basis, of any of the 12 major leaf producers. Decomposition rates of leaves from five common flood-plain tree species were measured using a standard leaf-bag technique. Leaf decomposition was highly species-dependent. Tupelo (Nyssa spp.) and sweetgum (Liquidambar styraciflua) leaves decomposed completely in 6 months when flooded by river water. Leaves of baldcypress (Taxodium distichum) and diamond-leaf oak (Quercus laurifolia) were much more resistant. Water hickory (Carya aquatica) leaves showed intermediate decomposition rates. Decomposition of all species was greatly reduced in dry environments. Carbon and biomass loss rates from the leaves were nearly linear over a 6-month period, but nitrogen and phosphorus leaching was nearly complete within 1 month. Much of the organic substance may be recycled in the forest ecosystem, but annual flooding of the river provides an important mechanism for mobilization of the litter-fall products.

Florida↗
USGS2021

Groundwater/surface-water interactions in the Partridge River Basin and evaluation of hypothetical future mine pits, Minnesota

The Partridge River Basin (PRB) covers 156 square miles in northeastern Minnesota with headwaters in the Mesabi Iron Range. The basin is characterized by extensive wetlands, lakes, and streams in poorly drained and often thin glacial material overlying Proterozoic bedrock. To better understand the interaction between these extensive surface water features and the groundwater system, a three-dimensional, steady-state, groundwater-flow model of the PRB was developed by the U.S. Geological Survey in cooperation with the Great Lakes Indian Fish & Wildlife Commission using the finite-difference computer code MODFLOW-NWT. The model simulates steady-state base flow in streams and groundwater interactions using the streamflow routing (SFR2) package. Existing mining features including tailings basins, stockpiles, pumped mine pits, and flooded mine pits were simulated using either high hydraulic conductivity zones or the drain (DRN) package. The unsaturated zone flow (UZF) package was used to better represent the groundwater system in areas with a high water table and for wetlands often associated with such areas. UZF typically is used to represent unsaturated zone processes but also can simulate the rejection of recharge and groundwater discharge to the land surface when the water table is near land surface. The steady-state model used data from the 2011 to 2013 period when 2011 high-resolution land surface (light detecting and ranging [lidar]) data were available that reflected land-surface and water elevations from mining activity in the basin. The parameter-estimation software suite PEST_HP was used to obtain a best fit of the modeled to measured groundwater levels, streamflow, pit inflow rates, and mapped peat deposits. The PEST calibration used the target residuals from two models with the same model parameters and targets from two separate periods: (1) a 1995–2015 calibration model, which provided a larger number of calibration targets, and (2) a 2011–2013 mining conditions model, which included calibration targets that reflected conditions consistent with the modeled mine-workings topography. Calibration of the PRB model resulted in ranges of glacial horizontal hydraulic conductivity parameters that generally agreed with literature values and other models of the region. Horizontal hydraulic conductivity of the bedrock was higher in the upper bedrock layers where numerous and continuous fractures have been observed and lower in the deeper bedrock layers. Average basin-wide calibrated infiltration was 5.3 inches per year. An average of 4.6 inches per year of infiltration crosses the water table and becomes recharge and 0.7 inch per year is rejected by UZF due to saturated conditions at the land surface. Simulated groundwater runoff (the sum of rejected recharge and groundwater seepage to the land surface) can either be routed to streams or removed from the model as evapotranspiration. The calibrated model indicates relatively shallow groundwater-flow paths dominating and approximately 50 percent of the stream base flow coming from groundwater runoff. The 2011–2013 mining conditions model was then used to develop five model scenarios simulating the response of the groundwater and surface-water system to potential hydrologic stress. The purpose of these mine pit scenarios is to present a possible workflow to quantify a model’s uncertainty for a given model forecast and serve as a possible guide for initial data collection that may improve a future model’s ability to make such a forecast. The scenarios included one scenario with the currently existing Peter Mitchell pit at final buildout and flooded to an elevation of 1,500 feet, and four scenarios with a hypothetical, new mine pit plus the flooded Peter Mitchell at final buildout. The five model scenarios were used to forecast streamflow at six locations in the PRB, pit inflow rates for the new mine pits and the flooded Peter Mitchell pit, and the average depth to water in 12 wetlands. A linear uncertainty analysis was performed using information from the PEST calibration and tools in the PyEMU python package to assess model uncertainty propagation to the model forecasts. Streamflows generally were reduced with future mining and the greatest streamflow reductions occurred from the flooded Peter Mitchell Pit, probably due to its large size. Average depth to groundwater in wetlands was most affected the closer the wetland was to a new mine pit. Linear uncertainty methods were also used to evaluate data worth, which is the ability for potential new groundwater elevation observations to reduce the uncertainty in scenario forecasts. Data worth was performed for a grid of new hydraulic head observations. Overall, areas with nonnegligible data worth generally corresponded to wetland areas with no groundwater seepage to land surface from UZF. These model behaviors indicated that the land-surface boundary condition simulated by the UZF package was pinning the groundwater elevations to the land surface in areas with groundwater seepage (33 percent of the 2011–2013 base conditions model) such that the sensitivity to new observations in these areas was minimal. Therefore, representing wetlands as boundary conditions minimized the usefulness of data worth calculations because wetland areas were present over a large part of the model domain. Probabilistic capture zones were estimated for each of the mines in the model scenarios. A capture zone represents the area contributing recharge to a model feature, like a well or a mine pit, and can be calculated by forward tracking particles from the water table. By using Monte Carlo techniques, it is possible to generate estimated capture zones that include the probability of recharge capture given the uncertainty present in the model. Monte Carlo techniques use randomly generated model parameter sets sampled from a plausible parameter range to create many possible realizations. The resulting capture zone arrays were calculated by tallying the total number of realizations in which a particle from a model cell was captured by the feature. Probabilities from the Monte Carlo runs ranged from 1 (captured in 100 percent of the runs) near the pits to 0 (captured in 0 percent of the runs) at the edges of the capture zone. Capture zones were not always spatially continuous; for example, the capture zone for the proposed mine pits south of the flooded Peter Mitchell pit was discontinuous with capture surrounding the proposed mine pit and north of the flooded Peter Mitchell pit. This northern section represents deeper groundwater flow paths that originate in the topographic high, move under the flooded pit, and discharge into the proposed pit. This pattern of capture indicates the possibility of some deeper flow through the upper fractured bedrock when the shallow groundwater flow system is modified. These results underscore that future site-specific applications of the base condition model require the input of site-specific data and recalibration to focus on the site of interest.

Minnesota↗
USGS2003

Monthly Strontium/Calcium oscillations in symbiotic coral aragonite: Biological effects limiting the precision of the paleotemperature proxy

In thermodynamic equilibrium with sea water the Sr/Ca ratio of aragonite varies predictably with temperature and the Sr/Ca ratio in coral have thus become a frequently used proxy for past Sea Surface Temperature (SST). However, biological effects can offset the Sr/Ca ratio from its equilibrium value. We report high spatial resolution ion microprobe analyses of well defined skeletal elements in the reef‐building coral Porites lutea that reveal distinct monthly oscillations in the Sr/Ca ratio, with an amplitude in excess of ten percent. The extreme Sr/Ca variations, which we propose result from metabolic changes synchronous with the lunar cycle, introduce variability in Sr/Ca measurements based on conventional sampling techniques well beyond the analytical precision. These variations can limit the accuracy of Sr/Ca paleothermometry by conventional sampling techniques to about 2°C. Our results may help explain the notorious difficulties involved in obtaining an accurate and consistent calibration of the Sr/Ca vs. SST relationship.

Geophysical Research Letters↗
USGS2005

Preparations for water sampling

The National Field Manual for the Collection of Water-Quality Data (National Field Manual) provides guidelines and standard procedures for U.S. Geological Survey (USGS) personnel who collect data used to assess the quality of the Nation’s surface-water and ground-water resources. This chapter addresses field-trip preparations, including selection of sample-collection sites for studies of surface-water quality, site reconnaissance and well selection for studies of groundwater quality, and the establishment of electronic files and field files and folders for a sampling site. Each chapter of the National Field Manual is published separately and revised periodically. Newly published and revised chapters are posted on the World Wide Web on the USGS page "National Field Manual for the Collection of Water-Quality Data." The URL for this page is http://pubs.water.usgs.gov/twri9A/ (accessed Jan. 31, 2005).

Techniques of Water-Resources Investigations↗
USGS2007

GIS methodology for quantifying channel change in Las Vegas, Nevada

This study applies spatial analyses to examine the consequences of accelerated urban expansion on a hydrologic system over a period of 24 years. Three sets of historical aerial photos are used in a GIS analysis to document the geomorphic history of Las Vegas Wash, which drains the rapidly growing Las Vegas urban area in southern Nevada. New spatial techniques are introduced to make quantitative measurements of the erosion at three specific time intervals in the hydrologic evolution of the channel and floodplain. Unlike other erosion studies that use two different elevation surfaces to assess erosion, this study used a single elevation surface to remove systematic and nonsystemic elevation errors. The spatial analysis quantifies channel changes for discrete time periods, calculates erosion volumes, and provides a foundation to examine how the specific mechanisms related to urban expansion have affected Las Vegas Wash. The erosion calculated over 24 years is the largest documented sediment loss attributed to the effect of rapid urban growth. ?? 2007 American Water Resources Association.

Journal of the American Water Resources Associatio↗
USGS2007

Mid-Pliocene Planktic Foraminifer Census Data from Ocean Drilling Program Hole 847C

Introduction The U.S. Geological Survey is conducting a long-term study of mid-Pliocene climatic and oceanographic conditions. One of the key elements of the study involves the use of quantitative composition of planktic foraminifer assemblages in conjunction with other proxies to constrain estimates of sea-surface temperature (SST) and to identify major oceanographic boundaries and water masses. Raw census data are made available as soon as possible after analysis through a series of reports that provide the basic data for future work. In this report we present raw census data (table 1) for planktic foraminifer assemblages in 25 samples from Ocean Drilling Program (ODP) Hole 847C. Ocean Drilling Program Hole 847C is located at 0.19?N., 95.32?W., in 3334.3 meters of water (fig. 1). A variety of statistical methods have been developed to transform foraminiferal census data in Pliocene sequences into quantitative estimates of Pliocene SST. Details of statistical techniques, taxonomic groupings, and oceanographic interpretations are presented in more formal publications (Dowsett and Poore, 1990, 1991; Dowsett, 1991, 2007; Dowsett and Robinson, 1998, 2007; Dowsett and others, 1996, 1999).

Data Series↗
USGS2017

Management implications of broadband sound in modulating wild silver carp (Hypophthalmichthys molitrix) behavior

Invasive silver carp (Hypophthalmichthys molitrix) dominate large regions of the Mississippi River drainage, outcompete native species, and are notorious for their prolific and unusual jumping behavior. High densities of juvenile and adult (~25 kg) carp are known to jump up to 3 m above the water surface in response to moving watercraft. Broadband sound recorded from an outboard motor (100 hp at 32 km/hr) can modulate their behavior in captivity; however, the response of wild silver carp to broadband sound has yet to be determined. In this experiment, broadband sound (0.06–10 kHz) elicited jumping behavior from silver carp in the Spoon River near Havana, IL independent of boat movement, indicating acoustic stimulus alone is sufficient to induce jumping. Furthermore, the number of jumping fish decreased with subsequent sound exposures. Understanding silver carp jumping is not only important from a behavioral standpoint, it is also critical to determine effective techniques for controlling this harmful species, such as herding fish into a net for removal.

Illinois↗
USGS2010

Stage measurement at gaging stations

Stream and reservoir stage are critical parameters in the computation of stream discharge and reservoir volume, respectively. In addition, a record of stream stage is useful in the design of structures that may be affected by stream elevation, as well as for the planning for various uses of flood plains. This report describes equipment and methodology for the observation, sensing, and recording of stage in streams and reservoirs. Although the U.S. Geological Survey (USGS) still uses the traditional, basic stilling-well float system as a predominant gaging station, modern electronic stage sensors and water-level recorders are now commonly used. Bubble gages coupled with nonsubmersible pressure transducers eliminate the need for stilling wells. Submersible pressure transducers have become common in use for the measurement of stage in both rivers and lakes. Furthermore, noncontact methods, such as radar, acoustic, and laser methods of sensing water levels, are being developed and tested, and in the case of radar, are commonly used for the measurement of stage. This report describes commonly used gaging-station structures, as well as the design and operation of gaging stations. Almost all of the equipment and instruments described in this report will meet the accuracy standard set by the USGS Office of Surface Water (OSW) for the measurement of stage for most applications, which is ±0.01 foot (ft) or 0.2 percent of the effective stage. Several telemetry systems are used to transmit stage data from the gaging station to the office, although satellite telemetry has become the standard. These telemetry systems provide near real-time stage data, as well as other information that alerts the hydrographer to extreme or abnormal events, and instrument malfunctions.

Techniques and Methods↗