Roughness coefficients for stream channels in Arizona

USGS Publications Warehouse

Aldridge, B.N.; Garrett, J.M.

1973-01-01

       n in which V = mean cross-sectional velocity of flow, in feet per second; R = hydraulic radius at a cross section, which is the cross-sectional area divided by the wetter perimeter, in feet; Se = energy slope; and n = coefficient of roughness. Many research studies have been made to determine "n" values for open-channel flow (Carter and others, 1963). Guidelines for selecting coefficient of roughness for stream channels are given in most of the literature of stream-channel hydraulics, but few of the data relate directly to streams of Arizona, The U.S> Geological Survey, at the request of the Arizona Highway Department, assembled the color photographs and tables of the Manning "n" values in this report to aid highway engineers in the selection of roughness coefficients for Arizona streams. Most of the photographs show channel reaches for which values of "n" have been assigned by experienced Survey personnel; a few photographs are included for reaches where "n" values have been verified. Verified "n" values are computed from a known discharge and measured channel geometry. Selected photographs of stream channels for which "n" values have been verified are included in U.S. Geological Survey Water-Supply Paper 1849 (Barnes, 1967); stereoscopic slides of Barnes' (1967) photographs and additional photographs can be inspected at U.S> Geological Survey offices in: 2555 E. First Street, Tucson; and 5017 Federal Building, 230 N. First Avenue, Phoenix.

Aquatic organism passage at road-stream crossings—synthesis and guidelines for effectiveness monitoring

USGS Publications Warehouse

Hoffman, Robert L.; Dunham, Jason B.; Hansen, Bruce P.

2012-01-01

Restoration and maintenance of passage for aquatic organisms at road-stream crossings represents a major management priority, involving an investment of hundreds of millions of dollars (for example, U.S. Government Accounting Office, 2001). In recent years, passage at hundreds of crossings has been restored, primarily by replacing barrier road culverts with bridges or stream simulation culverts designed to pass all species and all life stages of aquatic life and simulate natural hydro-geomorphic processes (U.S. Forest Service, 2008). The current situation has motivated two general questions: 1. Are current design standards for stream simulation culverts adequately re-establishing passage for aquatic biota? and 2. How do we monitor and evaluate effectiveness of passage restoration? To address the latter question, a national workshop was held in March 2010, in Portland, Oregon. The workshop included experts on aquatic organism passage from across the nation (see table of participants, APPENDIX) who addressed four classes of methods for monitoring effectiveness of aquatic organism passage—individual movement, occupancy, demography, and genetics. This report has been written, in part, for field biologists who will be undertaking and evaluating the effectiveness of aquatic organism passage restoration projects at road-stream crossings. The report outlines basic methods for evaluating road-stream crossing passage impairment and restoration and discusses under what circumstances and conditions each method will be useful; what questions each method can potentially answer; how to design and implement an evaluation study; and points out the fundamental reality that most evaluation projects will require special funding and partnerships among researchers and resource managers. The report is organized into the following sections, which can be read independently: 1. Historical context: In this section, we provide a brief history of events leading up to the present situation involving aquatic organism passage as a useful context for the issues covered herein. 2. Importance of connectivity for aquatic organisms: In this section, we provide background information regarding the movement characteristics of aquatic organisms and their vulnerability to passage impairment, and the importance of connectivity for a broad diversity of aquatic vertebrates and invertebrates. This section should be useful for practitioners in selecting what species to monitor in relation to aquatic organism passage. 3. Methods for evaluating aquatic organism passage: In this section, we present a range of perspectives on alternatives for assessing and monitoring aquatic organism passage impairment and the effectiveness of passage restoration actions, including the following methods: Individual Movement, Occupancy Models, Abundance (Demography), and Molecular Genetic Markers. 4. Relevance, strengths, and limitations of the four methods: In this section, we discuss the utility of each of the methods as a tool for assessing and quantifying passage impairment and restoration effectiveness. 5. Guidelines for selecting a method: In this section, we review some fundamental criteria and guidelines to consider when selecting a method for monitoring in the context of answering three important questions that should be addressed when developing a plan for evaluating aquatic organism passage. 6. Study and monitoring design considerations: In this section, we discuss four key design elements that need to be considered when developing a monitoring design for assessing passage impairment and restoration. The basic objectives of the report are to: 1. Review the movement characteristics of five groups of aquatic organisms that inhabit streams and to assess their general vulnerability to passage impairment at road-stream crossings; 2. Review four methods for monitoring aquatic organism passage impairment and the effectiveness of actions to restore passage at road-stream crossing structures; 3. Assess the relevance, strengths, and limitations of each method as a monitoring tool; 4. Identify and discuss guidelines that will be useful for selecting a monitoring method; and 5. Discuss what we have identified as the four key elements that need to be considered when developing a monitoring design for assessing passage impairment and restoration at road-stream crossings.

Probe systems for static pressure and cross-stream turbulence intensity

NASA Technical Reports Server (NTRS)

Rossow, Vernon, J.

1991-01-01

A recent study of total-pressure probes for use in highly turbulent streams is extended herein by developing probe systems that measure time-averaged static or ambient pressure and turbulence intensity. Arrangements of tubular probes of circular and elliptical cross section are described that measure the pressure at orifices on the sides of the probes to obtain different responses to the cross-stream velocity fluctuations. When the measured data are combined to remove the effect of the presence of the probes on the local pressure, the time-averaged static pressure and the cross-stream components of turbulence intensity can be determined. If a system of total pressure tubes, as described in an accompanying paper, is added to the static pressure group to form a single cluster, redundant measurements are obtained that permit accuracy and consistency checks.

Using LiDAR to Estimate Surface Erosion Volumes within the Post-storm 2012 Bagley Fire

NASA Astrophysics Data System (ADS)

Mikulovsky, R. P.; De La Fuente, J. A.; Mondry, Z. J.

2014-12-01

The total post-storm 2012 Bagley fire sediment budget of the Squaw Creek watershed in the Shasta-Trinity National Forest was estimated using many methods. A portion of the budget was quantitatively estimated using LiDAR. Simple workflows were designed to estimate the eroded volume's of debris slides, fill failures, gullies, altered channels and streams. LiDAR was also used to estimate depositional volumes. Thorough manual mapping of large erosional features using the ArcGIS 10.1 Geographic Information System was required as these mapped features determined the eroded volume boundaries in 3D space. The 3D pre-erosional surface for each mapped feature was interpolated based on the boundary elevations. A surface difference calculation was run using the estimated pre-erosional surfaces and LiDAR surfaces to determine volume of sediment potentially delivered into the stream system. In addition, cross sections of altered channels and streams were taken using stratified random selection based on channel gradient and stream order respectively. The original pre-storm surfaces of channel features were estimated using the cross sections and erosion depth criteria. Open source software Inkscape was used to estimate cross sectional areas for randomly selected channel features and then averaged for each channel gradient and stream order classes. The average areas were then multiplied by the length of each class to estimate total eroded altered channel and stream volume. Finally, reservoir and in-channel depositional volumes were estimated by mapping channel forms and generating specific reservoir elevation zones associated with depositional events. The in-channel areas and zones within the reservoir were multiplied by estimated and field observed sediment thicknesses to attain a best guess sediment volume. In channel estimates included re-occupying stream channel cross sections established before the fire. Once volumes were calculated, other erosion processes of the Bagley sedimentation study, such as surface soil erosion were combined to estimate the total fire and storm sediment budget for the Squaw Creek watershed. The LiDAR-based measurement workflows can be easily applied to other sediment budget studies using one high resolution LiDAR dataset.

Bankfull characteristics of Ohio streams and their relation to peak streamflows

USGS Publications Warehouse

Sherwood, James M.; Huitger, Carrie A.

2005-01-01

Regional curves, simple-regression equations, and multiple-regression equations were developed to estimate bankfull width, bankfull mean depth, bankfull cross-sectional area, and bankfull discharge of rural, unregulated streams in Ohio. The methods are based on geomorphic, basin, and flood-frequency data collected at 50 study sites on unregulated natural alluvial streams in Ohio, of which 40 sites are near streamflow-gaging stations. The regional curves and simple-regression equations relate the bankfull characteristics to drainage area. The multiple-regression equations relate the bankfull characteristics to drainage area, main-channel slope, main-channel elevation index, median bed-material particle size, bankfull cross-sectional area, and local-channel slope. Average standard errors of prediction for bankfull width equations range from 20.6 to 24.8 percent; for bankfull mean depth, 18.8 to 20.6 percent; for bankfull cross-sectional area, 25.4 to 30.6 percent; and for bankfull discharge, 27.0 to 78.7 percent. The simple-regression (drainage-area only) equations have the highest average standard errors of prediction. The multiple-regression equations in which the explanatory variables included drainage area, main-channel slope, main-channel elevation index, median bed-material particle size, bankfull cross-sectional area, and local-channel slope have the lowest average standard errors of prediction. Field surveys were done at each of the 50 study sites to collect the geomorphic data. Bankfull indicators were identified and evaluated, cross-section and longitudinal profiles were surveyed, and bed- and bank-material were sampled. Field data were analyzed to determine various geomorphic characteristics such as bankfull width, bankfull mean depth, bankfull cross-sectional area, bankfull discharge, streambed slope, and bed- and bank-material particle-size distribution. The various geomorphic characteristics were analyzed by means of a combination of graphical and statistical techniques. The logarithms of the annual peak discharges for the 40 gaged study sites were fit by a Pearson Type III frequency distribution to develop flood-peak discharges associated with recurrence intervals of 2, 5, 10, 25, 50, and 100 years. The peak-frequency data were related to geomorphic, basin, and climatic variables by multiple-regression analysis. Simple-regression equations were developed to estimate 2-, 5-, 10-, 25-, 50-, and 100-year flood-peak discharges of rural, unregulated streams in Ohio from bankfull channel cross-sectional area. The average standard errors of prediction are 31.6, 32.6, 35.9, 41.5, 46.2, and 51.2 percent, respectively. The study and methods developed are intended to improve understanding of the relations between geomorphic, basin, and flood characteristics of streams in Ohio and to aid in the design of hydraulic structures, such as culverts and bridges, where stability of the stream and structure is an important element of the design criteria. The study was done in cooperation with the Ohio Department of Transportation and the U.S. Department of Transportation, Federal Highway Administration.

30 CFR 783.25 - Cross sections, maps, and plans.

Code of Federal Regulations, 2014 CFR

2014-07-01

...) Elevations and locations of monitoring stations used to gather data on water quality and quantity, fish and... aquifers on cross-sections and contour maps; (7) Location of surface water bodies such as streams, lakes... permit area; (9) Location and dimensions of existing areas of spoil, waste, coal development waste, and...

30 CFR 783.25 - Cross sections, maps, and plans.

Code of Federal Regulations, 2011 CFR

2011-07-01

...) Elevations and locations of monitoring stations used to gather data on water quality and quantity, fish and... aquifers on cross-sections and contour maps; (7) Location of surface water bodies such as streams, lakes... permit area; (9) Location and dimensions of existing areas of spoil, waste, coal development waste, and...

30 CFR 783.25 - Cross sections, maps, and plans.

Code of Federal Regulations, 2010 CFR

2010-07-01

...) Elevations and locations of monitoring stations used to gather data on water quality and quantity, fish and... aquifers on cross-sections and contour maps; (7) Location of surface water bodies such as streams, lakes... permit area; (9) Location and dimensions of existing areas of spoil, waste, coal development waste, and...

30 CFR 783.25 - Cross sections, maps, and plans.

Code of Federal Regulations, 2012 CFR

2012-07-01

...) Elevations and locations of monitoring stations used to gather data on water quality and quantity, fish and... aquifers on cross-sections and contour maps; (7) Location of surface water bodies such as streams, lakes... permit area; (9) Location and dimensions of existing areas of spoil, waste, coal development waste, and...

30 CFR 783.25 - Cross sections, maps, and plans.

Code of Federal Regulations, 2013 CFR

2013-07-01

...) Elevations and locations of monitoring stations used to gather data on water quality and quantity, fish and... aquifers on cross-sections and contour maps; (7) Location of surface water bodies such as streams, lakes... permit area; (9) Location and dimensions of existing areas of spoil, waste, coal development waste, and...

Quantifying fish habitat associated with stream simulation design culverts in northern Wisconsin

Treesearch

A. Timm; D. Higgins; J. Stanovick; R. Kolka; S. Eggert

2017-01-01

This study investigated the effects of culvert replacement design on fish habitat and fish weight by comparing substrate diversity and weight at three stream simulation (SS)-design and three bankfull and backwater (BB)-design sites on the Chequamegon-Nicolet National Forest, Wisconsin. Stream channel cross-sections, Wolman substrate particle counts, and single-pass...

A design method for entrance sections of transonic wind tunnels with rectangular cross sections

NASA Technical Reports Server (NTRS)

Lionel, L.; Mcdevitt, J. B.

1975-01-01

A mathematical technique developed to design entrance sections for transonic or high-speed subsonic wind tunnels with rectangular cross sections is discribed. The transition from a circular cross-section setting chamber to a rectangular test section is accomplished smoothly so as not to introduce secondary flows (vortices or boundary-layer separation) into a uniform test stream. The results of static-pressure measurements in the transition region and of static and total-pressure surveys in the test section of a pilot model for a new facility at the Ames Research Center are presented.

Regionalized equations for bankfull-discharge and channel characteristics of streams in New York State—Hydrologic Region 6 in the Southern Tier of New York

USGS Publications Warehouse

Mulvihill, Christiane I.; Ernst, Anne G.; Baldigo, Barry P.

2005-01-01

Equations that relate bankfull discharge and channel characteristics (width, depth, and cross-sectional area) to drainage-area size at gaged sites are needed to define bankfull discharge and channel dimensions at ungaged sites and to provide information for watershed assessments, stream-channel classification, and the design of stream-restoration projects. Such equations are most accurate if derived from streams within an area of uniform hydrologic, climatic, and physiographic conditions and applied only within that region. In New York State, eight hydrologic regions were previously defined on the basis of similar high-flow (flood) characteristics. This report presents drainage areas and associated bankfull characteristics (discharge and channel dimensions) for surveyed streams in southwestern New York (Region 6).Stream-survey data and discharge records from 11 active (currently gaged) sites and 3 inactive (discontinued) sites were used in regression analyses to relate bankfull discharge and bankfull channel width, depth, and cross-sectional area to the size of the drainage area. The resulting equations are:(1) bankfull discharge, in cubic feet per second = 48.0*(drainage area, in square miles)0.842;(2) bankfull channel width, in feet = 16.9*(drainage area, in square miles)0.419;(3) bankfull channel depth, in feet = 1.04*(drainage area, in square miles)0.244; and(4) bankfull channel cross-sectional area, in square feet = 17.6*(drainage area, in square miles)0.662.The coefficient of determination (R2) for these four equations were 0.90, 0.79, 0.64, and 0.89, respectively. The high correlation coefficients for bankfull discharge and cross-sectional area indicate that much of the variation in these variables is explained by the size of the drainage area. The smaller correlation coefficients for bankfull channel width and depth indicate that other factors also affect these relations. Recurrence intervals for the estimated bankfull discharge of each stream ranged from 1.01 to 2.35 years; the mean recurrence interval was 1.54 years. The 14 surveyed streams were classified by Rosgen stream type; most were C-type reaches, with occasional B-type reaches. The Region 6 equation (curve) for bankfull discharge was compared with equations previously developed for four other large areas in New York State and southeastern Pennsylvania. The differences among results indicate that, although the equations need to be refined by region before being applied by water-resources managers to local planning and design efforts, similar regions have similar relations between bankfull discharge and channel characteristics.

Stream channel reference sites: An illustrated guide to field technique

Treesearch

Cheryl C Harrelson; C. L. Rawlins; John P. Potyondy

1994-01-01

This document is a guide to establishing permanent reference sites for gathering data about the physical characteristics of streams and rivers. The minimum procedure consists of the following: (1) select a site, (2) map the site and location, (3) measure the channel cross-section, (4) survey a longitudinal profile of the channel, (5) measure stream flow, (6) measure...

Regional curve development and selection of a reference reach in the non-urban, lowland sections of the Piedmont physiographic province, Pennsylvania and Maryland

USGS Publications Warehouse

White, Kirk E.

2001-01-01

Stream-restoration projects utilizing naturalstream designs frequently are based on the bankfull- channel characteristics of a stream reach that is accommodating streamflow and sediment transport without excessive erosion or deposition. The bankfull channel is identified by the use of field indicators and confirmed with tools such as regional curves. Channel dimensions were surveyed at six streamflow-measurement stations operated by the U.S. Geological Survey in the Gettysburg-Newark Lowlands Section and Piedmont Lowlands Section of the Piedmont Physiographic Province in Pennsylvania and Maryland. Regional curves were developed from regression analyses of the relation between drainage area and cross-sectional area, mean depth, width, and streamflow of the bankfull channel. Regional curves were used to confirm the identification of the bankfull channel at a reference reach. Stream dimensions and characteristics of the reference reach were measured for extrapolation into the design of a steam-restoration project on Bermudian Creek in Adams County, Pa.Dimensions for cross-sectional area, mean depth, width, and computed streamflow of the bankfull channel in all surveyed riffle cross sections in the reference reach were within the 95-percent confidence interval bounding the regression line representing bankfull channel geometry in the Lowland Sections of the Piedmont Physiographic Province. The average bankfull cross-sectional area, bankfull mean depth, and computed bankfull discharge for riffle cross sections in the reference reach ranged from 15.4 to 16.5 percent less than estimates determined from the lowland regional curves. Average bankfull channel width was about 2 percent greater than estimates. Cross-sectional area, mean depth, and computed streamflow corresponding to the bankfull stage at the reference reach were 31.4, 44.4, and 9.6 percent less, respectively, than estimates derived from the regional curves developed by Dunne and Leopold in 1978. Average bankfull channel width at the reference reach was 16.7 percent greater than the Dunne and Leopold estimate.The concepts of regional curves and reference reaches can be valuable tools to support efforts in stream restoration. Practitioners of stream restoration need to recognize them as such and realize their limitations. The small number of stations available for analysis is a major limiting factor in the strength of the results of this investigation. Subjective selection criteria may have unnecessarily eliminated streamflow-measurement stations that could have been included in the regional curves. A bankfull discharge with a recurrence interval within the 1- to 2-year range was used as a criteria for confirmation of the bankfull stage at each streamflow-measurement station. Many researchers accept this range for recurrence interval of the bankfull discharge; however, literature provides contradictory evidence. The use of channel-characteristics data from a reference reach without any monitoring data to document the stability of the reference reach over time is a topic of debate.

Combustor air flow control method for fuel cell apparatus

DOEpatents

Clingerman, Bruce J.; Mowery, Kenneth D.; Ripley, Eugene V.

2001-01-01

A method for controlling the heat output of a combustor in a fuel cell apparatus to a fuel processor where the combustor has dual air inlet streams including atmospheric air and fuel cell cathode effluent containing oxygen depleted air. In all operating modes, an enthalpy balance is provided by regulating the quantity of the air flow stream to the combustor to support fuel cell processor heat requirements. A control provides a quick fast forward change in an air valve orifice cross section in response to a calculated predetermined air flow, the molar constituents of the air stream to the combustor, the pressure drop across the air valve, and a look up table of the orifice cross sectional area and valve steps. A feedback loop fine tunes any error between the measured air flow to the combustor and the predetermined air flow.

Data Evaluation of Actinide Cross Sections: 238Pu, 237Pu, and 236Pu

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guaglioni, S.; Jurgenson, E.; Descalle, M. A.

This report documents the recent evaluation of the 236Pu, 237Pu, and 238Pu cross section sets. Nuclear data evaluation is the fundamental interface that takes measured nuclear cross section data and turns them into a continuous curve that 1) is consistent with other measurements and nuclear reaction theory/models, and 2) is required by down-stream users. All experiments that generate nuclear data need to include an evaluation step for their data to be broadly useful to the end users.

Digital database of channel cross-section surveys, Mount St. Helens, Washington

USGS Publications Warehouse

Mosbrucker, Adam R.; Spicer, Kurt R.; Major, Jon J.; Saunders, Dennis R.; Christianson, Tami S.; Kingsbury, Cole G.

2015-08-06

Stream-channel cross-section survey data are a fundamental component to studies of fluvial geomorphology. Such data provide important parameters required by many open-channel flow models, sediment-transport equations, sediment-budget computations, and flood-hazard assessments. At Mount St. Helens, Washington, the long-term response of channels to the May 18, 1980, eruption, which dramatically altered the hydrogeomorphic regime of several drainages, is documented by an exceptional time series of repeat stream-channel cross-section surveys. More than 300 cross sections, most established shortly following the eruption, represent more than 100 kilometers of surveyed topography. Although selected cross sections have been published previously in print form, we present a comprehensive digital database that includes geospatial and tabular data. Furthermore, survey data are referenced to a common geographic projection and to common datums. Database design, maintenance, and data dissemination are accomplished through a geographic information system (GIS) platform, which integrates survey data acquired with theodolite, total station, and global navigation satellite system (GNSS) instrumentation. Users can interactively perform advanced queries and geospatial time-series analysis. An accuracy assessment provides users the ability to quantify uncertainty within these data. At the time of publication, this project is ongoing. Regular database updates are expected; users are advised to confirm they are using the latest version.

Free stream turbulence and density ratio effects on the interaction region of a jet in a cross flow

NASA Technical Reports Server (NTRS)

Wark, C. E.; Foss, J. F.

1984-01-01

Jets of low temperature air are introduced into the aft sections of gas turbine combustors for the purpose of cooling the high temperature gases and quenching the combustion reactions. Research studies, motivated by this complex flow field, have been executed by introducing a heated jet into the cross stream of a wind tunnel. The investigation by Kamotani and Greber stands as a prime example of such investigations and it serves as the principal reference for the present study. The low disturbance level of the cross stream, in their study and in similar research investigations, is compatible with an interest in identifying the basic features of this flow field. The influence of the prototypes' strongly disturbed cross flow is not, however, made apparent in these prior investigations.

Streambank Protection and Erosion Control.

DTIC Science & Technology

1987-01-01

TABLE OF CONTENTS N CHAPTER ONE - INTRODUCTION ----------------------------------------- -- 1. 1.1 Purpose...downstream cross sectional area by stream bank erosion and bed scour to accommodate the increased flow. This may be caused by poor planning and assessment...the magnitude, except for very large floods which occur infrequently. 3.2 Channel Geometry [6] .*. Channel geometry of a river cross section is an

Use of tracer injections and synoptic sampling to measure metal loading from acid mine drainage

USGS Publications Warehouse

Kimball, Briant A.

1997-01-01

Thousands of abandoned and inactive mines are located in environmentally sensitive mountain watersheds. Cost-effective remediation of the effects of metals from mining in these watersheds requires knowledge of the most significant sources of metals. The significance of a given source depends on the toxicity of a particular metal, how much of the metal enters the stream, and whether or not the metal remains in the stream in a toxic form. This discussion deals with accounting for how much metal enters the stream and whether it stays in the stream. The amount of metal entering the stream is called the mass loading and is calculated as the product of metal concentration and stream discharge. The overall effect of high metal concentrations on streams and aquatic organisms is unclear without discharge measurements.A traditional discharge measurement is obtained by dividing a stream into small sections and measuring the cross-sectional area and the average water velocity in each section. Summing the measurements of all the sections gives the discharge of the entire stream. This method works well where the channel bottom and banks are smooth. In mountain streams, however, the stream bottom typically is covered with cobbles, allowing much of the water to flow through the cobbles of the streambed where it cannot be measured by a flow meter (fig. 1). Thus, accurate discharge measurements are difficult to obtain in mountain streams, even under the best of conditions.

Probe systems for measuring static pressure and turbulence intensity in fluid streams

NASA Technical Reports Server (NTRS)

Rossow, Vernon J. (Inventor)

1993-01-01

A method and an apparatus for measuring time-averaged static or ambient pressure and turbulence intensity in a turbulent stream are discussed. The procedure involves placing a plurality of probes in the stream. Each probe responds in a different manner to characteristics of the fluid stream, preferably as a result of having varying cross sections. The responses from the probes are used to eliminate unwanted components in the measured quantities for accurate determination of selected characteristics.

Understanding Stream Channel Sediment Source Contributions For The Paradise Creek Watershed In Northern Idaho

NASA Astrophysics Data System (ADS)

Rittenburg, R.; Boll, J.; Brooks, E. S.

2013-12-01

Excess sediment from agricultural areas has been a major source of impairment for water bodies, resulting in the implementation of mitigation measures across landscapes. Watershed scale reductions often target upland erosion as key non-point sources for sediment loading. Stream channel dynamics, however, also play a contributing role in sediment loading in the form of legacy sediments, channel erosion and deposition, and buffering during storm events. In-stream contributions are not well understood, and are a potentially important consideration for Total Maximum Daily Loads (TMDLs). The objective of this study is to differentiate stream bank and stream bed sediment contributions and better understand the role of legacy sediments. The study area is the Paradise Creek Watershed in northern Idaho. We modeled sediment yield to the channel system using the Water Erosion Prediction Project (WEPP) model, and subsequent channel erosion and deposition using CONCEPTs. Field observations of cross-sections along the channel system over a 5-year period were collected to verify model simulations and to test the hypothesis that the watershed load was composed predominantly of legacy sediments. Our modeling study shows that stream channels contributed to 39% of the total annual sediment load for the basin, with a 19-year time lag between sediments entering the stream to leaving the watershed outlet. Observations from long-term cross sectional data in the watershed, and a sediment fingerprinting analysis will be presented to better understand sediment contributions from within the stream channel system.

Rock Erodibility as a Dynamic Variable Driven by the Interplay between Erosion and Weathering in Bedrock Channels: Examples from Great Falls, Virginia, USA

NASA Astrophysics Data System (ADS)

Hancock, G. S.; Huettenmoser, J.; Shobe, C. M.; Eppes, M. C.

2016-12-01

Rock erodibility in channels is a primary control on the stresses required to erode bedrock (e.g., Sklar and Dietrich, 2001). Erodibility tends to be treated as a uniform and fixed variable at the scale of channel cross-sections, particularly in models of channel profile evolution. Here we present field data supporting the hypothesis (Hancock et al., 2011) that erodibility is a dynamic variable, driven by the interplay between erosion rate and weathering processes within cross-sections. We hypothesize that rock weathering varies in cross-sections from virtually unweathered in the thalweg, where frequent stripping removes weathered rock, to a degree of weathering determined by the frequency of erosive events higher on the channel margin. We test this hypothesis on three tributaries to the Potomac River underlain by similar bedrock but with varying erosion rates ( 0.01 to 0.8 m/ky). At multiple heights within three cross-sections on three tributaries, we measured compressive strength with a Schmidt hammer, surface roughness with a contour gage, and density and length of visible cracks. Compressive strength decreased with height in all nine cross-sections by 10% to 50%, and surface roughness increased with height in seven cross-sections by 25% - 45%, with the remaining two showing minimal change. Crack density increased with height in the three cross-sections measured. Taken together these data demonstrate increases in weathering intensity, and presumably, rock erodibility, with height. The y-intercept of the relation between height and the three measured variables were nearly identical, suggesting that thalweg erodibility was similar on each channel, as predicted, even though erodibility higher in the cross-section were markedly different. The rate at which the three variables changed with height in each cross-section is strongly related to stream power. Assuming stream power is a reasonable surrogate for erosion rate, this result implies that erosion rate can be a primary influence on the distribution of erodibility within channel cross-sections. We conclude that the interplay between rates of erosion and weathering produces spatial as well as temporal variability in erodibility which, in turn, influences channel form and gradient.

Regionalized equations for bankfull-discharge and channel characteristics of streams in New York State—Hydrologic Region 5 in central New York

USGS Publications Warehouse

Westergard, Britt E.; Mulvihill, Christiane I.; Ernst, Anne G.; Baldigo, Barry P.

2005-01-01

Equations that relate drainage area to bankfull discharge and channel dimensions (width, depth, and cross-sectional area) at gaged sites are needed to define bankfull discharge and channel dimensions at ungaged sites and to provide information for the design of stream-restoration projects. Such equations are most accurate if derived from streams within an area of uniform hydrologic, climatic, and physiographic conditions and applied only within that region. A study to develop equations to predict bankfull data for ungaged streams in New York established eight regions that coincided with previously defined hydrologic regions. This report presents drainage areas and bankfull characteristics (discharge and channel dimensions) for streams in central New York (Region 5) selected for this pilot study.Stream-survey data and discharge records from seven active (currently gaged) sites and nine inactive (discontinued gaged) sites were used in regression analyses to relate size of drainage area to bankfull discharge and bankfull channel width, depth, and cross-sectional area. The resulting equations are:(1) bankfull discharge, in cubic feet per second = 45.3*(drainage area, in square miles)0.856;(2) bankfull channel width, in feet = 13.5*(drainage area, in square miles)0.449;(3) bankfull channel depth, in feet = 0.801*(drainage area, in square miles)0.373; and(4) bankfull channel cross-sectional area, in square feet = 10.8*(drainage area, in square miles)0.823.The high correlation coefficients (R2) for these four equations (0.96, 0.92, 0.91, 0.98, respectively) indicate that much of the variation in the variables is explained by the size of the drainage area. Recurrence intervals for the estimated bankfull discharge of each stream ranged from 1.11 to 3.40 years; the mean recurrence interval was 1.51 years. The 16 surveyed streams were classified by Rosgen stream type; most were mainly C-type reaches, with occasional B- and F-type reaches. The Region 5 equation was compared with equations developed for six other large areas in the Northeast. The major differences among results indicate a need to refine equations so they can be applied by water-resources managers to local planning and design efforts.

Comparing LiDAR-Generated to ground- surveyed channel cross-sectional profiles in a forested mountain stream

Treesearch

Brian C. Dietterick; Russell White; Ryan Hilburn

2012-01-01

Airborne Light Detection and Ranging (LiDAR) holds promise to provide an alternative to traditional ground-based survey methods for stream channel characterization and some change detection purposes, even under challenging landscape conditions. This study compared channel characteristics measured at 53 ground-surveyed and LiDAR-derived crosssectional profiles located...

Managed flood effects on beaver pond habitat in a desert riverine ecosystem, bill williams river, Arizona USA

USGS Publications Warehouse

Andersen, D.C.; Shafroth, P.B.; Pritekel, C.M.; O'Neill, M. W.

2011-01-01

The ecological effects of beaver in warm-desert streams are poorly documented, but potentially significant. For example, stream water and sediment budgets may be affected by increased evaporative losses and sediment retention in beaver ponds. We measured physical attributes of beaver pond and adjacent lotic habitats on a regulated Sonoran Desert stream, the Bill Williams River, after ???11 flood-free months in Spring 2007 and Spring 2008. Neither a predicted warming of surface water as it passed through a pond nor a reduction in dissolved oxygen in ponds was consistently observed, but bed sediment sorted to finest in ponds as expected. We observed a river segment-scale downstream rise in daily minimum stream temperature that may have been influenced by the series of ??100 beaver ponds present. Channel cross-sections surveyed before and after an experimental flood (peak flow 65 m3/s) showed net aggradation on nine of 13 cross-sections through ponds and three of seven through lotic reaches. Our results indicate that beaver affect riverine processes in warm deserts much as they do in other biomes. However, effects may be magnified in deserts through the potential for beaver to alter the stream thermal regime and water budget. ?? Society of Wetland Scientists 2011.

Hydraulic geometry of river cross sections; theory of minimum variance

USGS Publications Warehouse

Williams, Garnett P.

1978-01-01

This study deals with the rates at which mean velocity, mean depth, and water-surface width increase with water discharge at a cross section on an alluvial stream. Such relations often follow power laws, the exponents in which are called hydraulic exponents. The Langbein (1964) minimum-variance theory is examined in regard to its validity and its ability to predict observed hydraulic exponents. The variables used with the theory were velocity, depth, width, bed shear stress, friction factor, slope (energy gradient), and stream power. Slope is often constant, in which case only velocity, depth, width, shear and friction factor need be considered. The theory was tested against a wide range of field data from various geographic areas of the United States. The original theory was intended to produce only the average hydraulic exponents for a group of cross sections in a similar type of geologic or hydraulic environment. The theory does predict these average exponents with a reasonable degree of accuracy. An attempt to forecast the exponents at any selected cross section was moderately successful. Empirical equations are more accurate than the minimum variance, Gauckler-Manning, or Chezy methods. Predictions of the exponent of width are most reliable, the exponent of depth fair, and the exponent of mean velocity poor. (Woodard-USGS)

Measurement of stream channel habitat using sonar

USGS Publications Warehouse

Flug, Marshall; Seitz, Heather; Scott, John

1998-01-01

An efficient and low cost technique using a sonar system was evaluated for describing channel geometry and quantifying inundated area in a large river. The boat-mounted portable sonar equipment was used to record water depths and river width measurements for direct storage on a laptop computer. The field data collected from repeated traverses at a cross-section were evaluated to determine the precision of the system and field technique. Results from validation at two different sites showed average sample standard deviations (S.D.s) of 0.12 m for these complete cross-sections, with coefficient of variations of 10%. Validation using only the mid-channel river cross-section data yields an average sample S.D. of 0.05 m, with a coefficient of variation below 5%, at a stable and gauged river site using only measurements of water depths greater than 0.6 m. Accuracy of the sonar system was evaluated by comparison to traditionally surveyed transect data from a regularly gauged site. We observed an average mean squared deviation of 46.0 cm2, considering only that portion of the cross-section inundated by more than 0.6 m of water. Our procedure proved to be a reliable, accurate, safe, quick, and economic method to record river depths, discharges, bed conditions, and substratum composition necessary for stream habitat studies.

Regional Hydraulic Geometry Curves of the Northern Cascade Mountains, Chelan and King Counties, Washington State, USA

NASA Astrophysics Data System (ADS)

Gasperi, J. T.; McClung, J. M.; Hanson, D. L.

2006-12-01

The USDA-Natural Resources Conservation Service has developed regional hydraulic geometry curves relating drainage area to bankfull top width, mean depth and cross-sectional area for the east and west sides of the northern Cascade Mountains in Chelan and King Counties, Washington. NRCS surveyed 10 channel reaches with drainage areas from 1 to 1000 square miles within the Wenatchee River drainage of Chelan County and 10 channel reaches with drainage areas of 1 to 100 square miles within the Cedar and Green River drainages of King County. Selection criteria for stream reaches required a minimum of 20 years of USGS stream gage discharge records, unregulated flows and safe access. Survey data were collected with a Sokkia Total Station during low flow conditions from August 2004 to September 2005. NRCS measured a channel cross-section at each of the USGS stream gage sites and two or three additional cross-sections up and downstream. The authors also collected samples of bed material for gradation analysis and estimation of Manning's roughness coefficient, n. Bankfull elevations were estimated based on visual identification of field indicators and USGS flood discharges for the 50% exceedance probability event. Field data were evaluated with the Ohio DNR Reference Reach spreadsheet to determine bankfull top width, mean depth and cross-sectional area. We applied a simple linear regression to the data following USGS statistical methods to evaluate the closeness of fit between drainage area and bankfull channel dimensions. The resulting R2 values of 0.83 to 0.93 for the eastern Cascade data of Chelan County and 0.71 to 0.88 for the western Cascade data of King County indicate a close association between drainage area and bankfull channel dimensions for these two sets of data.

CYCLOTRON-WAVE INSTABILITIES,

DTIC Science & Technology

Interactions of waves on electron streams or plasmas are studied for several geometric configurations of finite cross section in a finite magnetic...velocity parallel to the magnetic field. It is further assumed that either macroscopic neutrality exists or static spacecharge forces are negligible. For...the most part the quasi-static analysis is used. For the case of two drifting streams cyclotron waves act to giveinstabilities which are either

Developing semi-analytical solution for multiple-zone transient storage model with spatially non-uniform storage

NASA Astrophysics Data System (ADS)

Deng, Baoqing; Si, Yinbing; Wang, Jia

2017-12-01

Transient storages may vary along the stream due to stream hydraulic conditions and the characteristics of storage. Analytical solutions of transient storage models in literature didn't cover the spatially non-uniform storage. A novel integral transform strategy is presented that simultaneously performs integral transforms to the concentrations in the stream and in storage zones by using the single set of eigenfunctions derived from the advection-diffusion equation of the stream. The semi-analytical solution of the multiple-zone transient storage model with the spatially non-uniform storage is obtained by applying the generalized integral transform technique to all partial differential equations in the multiple-zone transient storage model. The derived semi-analytical solution is validated against the field data in literature. Good agreement between the computed data and the field data is obtained. Some illustrative examples are formulated to demonstrate the applications of the present solution. It is shown that solute transport can be greatly affected by the variation of mass exchange coefficient and the ratio of cross-sectional areas. When the ratio of cross-sectional areas is big or the mass exchange coefficient is small, more reaches are recommended to calibrate the parameter.

Nonlinear Acoustics

DTIC Science & Technology

1974-02-14

when 1 = 0, 5n - 0, ’Y is the ratio of specific heats, v the kinematic viscosity and v’ the thermometric conductivity. S is the cross sectional area of...particles of aluminum were suspended in a xylol filled glass cylinder. The circulatory nature is clearly indicated. In another technique, Zarembo and... aluminum (from Liebermann [ I I I). uses Eq. (3.49) for Uac, under the assumption that the cross sectional area of forward streaming is identical to the

Long-term monitoring of stream bank stability under different vegetation cover

NASA Astrophysics Data System (ADS)

Krzeminska, Dominika; Skaalsveen, Kamilla; Kerkhof, Tjibbe

2017-04-01

Vegetated buffer zones are common environmental measures in many countries, including Norway. The presence of riparian vegetation on stream banks not only provides ecological benefits but also influence bank slope stability, through several complex interactions between riparian vegetation and hydro - mechanical processes. The hydrological processes associated with slope stability are complex and yet difficult to quantify, especially because their transient effects (e.g. changes throughout the vegetation life cycle). Additionally, there is very limited amount of field scale research focusing on investigation of coupled hydrological and mechanical influence of vegetation on stream bank behavior, accounting for both seasonal time scale and different vegetation type, and none dedicated to marine clay soils (typically soil for Norway). In order to fill this gap we established continues, long term hydrogeological monitoring o selected cross - section within stream bank, covered with different types of vegetation, typical for Norwegian agriculture areas (grass, shrubs, and trees). The monitoring involves methods such as spatial and temporal monitoring of soil moisture conditions, ground water level and fluctuation of water level in the stream. Herein we will present first 10 months of monitoring data: observed hydrological trends and differences between three cross - sections. Moreover, we will present first modelling exercises that aims to estimate stream banks stability with accounting on presence of different vegetation types using BSTEM and HYDRUS models. With this presentation, we would like to stimulate the discussion and get feedback that could help us to improve both, our experimental set up and analysis approach.

Flooding and sedimentation in Wheeling Creek basin, Belmont County, Ohio

USGS Publications Warehouse

Kolva, J.R.; Koltun, G.F.

1987-01-01

The Wheeling Creek basin, which is located primarily in Belmont County, Ohio, experienced three damaging floods and four less severe floods during the 29-month period from February 1979 through June 1981. Residents of the basin became concerned about factors that could have affected the severity and frequency of out-of-bank floods. In response to those concerns, the U.S. Geological Survey, in cooperation with the Ohio Department of Natural Resources, undertook a study to estimate peak discharges and recurrence intervals for the seven floods of interest, provide information on current and historical mining-related stream-channel fill or scour, and examine storm-period subbasin contributions to the sediment load in Wheeling Creek. Streamflow data for adjacent basins, rainfall data, and, in two cases, flood-profile data were used in conjunction with streamflow data subsequently collected on Wheeling Creek to provide estimates of peak discharge for the seven floods that occurred from February 1979 through June 1981. Estimates of recurrence intervals were assigned to the Peak discharges on the basin of regional regression equations that relate selected basin characteristics to peak discharge with fixed recurrence intervals. These estimates indicate that a statistically unusual number of floods with recurrence intervals of 2 years or more occurred within that time period. Three cross sections located on Wheeling Creek and four located on tributaries were established and surveyed quarterly for approximately 2 years. No evidence of appreciable stream-channel fill or scour was observed at any of the cross sections, although minor profile changes were apparent at some locations. Attempts were made to obtain historical cross-section profile data for comparison with current cross-section profiles; however, no usable data were found. Excavations of stream-bottom materials were made near the three main-stem cross-section locations and near the mouth of Jug Run. The bottom materials were examined for evidence of recently deposited sediments of mining-related origin. The only evidence of appreciable mining-related sediment deposition was found at Jug Run, and, to a lesser extent, at one main-stem site.

Benchmark measurements and calculations of a 3-dimensional neutron streaming experiment

NASA Astrophysics Data System (ADS)

Barnett, D. A., Jr.

1991-02-01

An experimental assembly known as the Dog-Legged Void assembly was constructed to measure the effect of neutron streaming in iron and void regions. The primary purpose of the measurements was to provide benchmark data against which various neutron transport calculation tools could be compared. The measurements included neutron flux spectra at four places and integral measurements at two places in the iron streaming path as well as integral measurements along several axial traverses. These data have been used in the verification of Oak Ridge National Laboratory's three-dimensional discrete ordinates code, TORT. For a base case calculation using one-half inch mesh spacing, finite difference spatial differencing, an S(sub 16) quadrature and P(sub 1) cross sections in the MUFT multigroup structure, the calculated solution agreed to within 18 percent with the spectral measurements and to within 24 percent of the integral measurements. Variations on the base case using a fewgroup energy structure and P(sub 1) and P(sub 3) cross sections showed similar agreement. Calculations using a linear nodal spatial differencing scheme and fewgroup cross sections also showed similar agreement. For the same mesh size, the nodal method was seen to require 2.2 times as much CPU time as the finite difference method. A nodal calculation using a typical mesh spacing of 2 inches, which had approximately 32 times fewer mesh cells than the base case, agreed with the measurements to within 34 percent and yet required on 8 percent of the CPU time.

Reconnaissance-level application of physical habitat simulation in the evaluation of physical habitat limits in the Animas Basin, Colorado

USGS Publications Warehouse

Milhous, Robert T.

2003-01-01

Bed material samples were collected at each site. These included samples of the armour, the substrate, and sand and fines deposited on the surface. At selected sites the stream morphology was measured. These measurements included one to three cross sections, stream discharge, and water surface elevations. The data are located in the files of the Fort Collins Science Center.

Comparison of Heat and Bromide as Ground Water Tracers Near Streams

USGS Publications Warehouse

Constantz, J.; Cox, M.H.; Su, G.W.

2003-01-01

Heat and bromide were compared as tracers for examining stream/ground water exchanges along the middle reaches of the Santa Clara River, California, during a 10-hour surface water sodium bromide injection test. Three cross sections that comprise six shallow (<1 m) piezometers were installed at the upper, middle, and lower sections of a 17 km long study reach, to monitor temperatures and bromide concentrations in the shallow ground water beneath the stream. A heat and ground water transport simulation model and a closely related solute and ground water transport simulation model were matched up for comparison of simulated and observed temperatures and bromide concentrations in the streambed. Vertical, one-dimensional simulations of sediment temperature were fitted to observed temperature results, to yield apparent streambed hydraulic conductivities in each cross section. The temperature-based hydraulic conductivities were assigned to a solute and ground water transport model to predict sediment bromide concentrations, during the sodium bromide injection test. Vertical, one-dimensional simulations of bromide concentrations in the sediments yielded a good match to the observed bromide concentrations, without adjustment of any model parameters except solute dispersivities. This indicates that, for the spatial and temporal scales examined on the Santa Clara River, the use of heat and bromide as tracers provide comparable information with respect to apparent hydraulic conductivities and fluxes for sediments near streams. In other settings, caution should be used due to differences in the nature of conservative (bromide) versus nonconservative (heat) tracers, particularly when preferential flowpaths are present.

A formula for calculating theoretical photoelectron fluxes resulting from the He/+/ 304 A solar spectral line

NASA Technical Reports Server (NTRS)

Richards, P. G.; Torr, D. G.

1981-01-01

A simplified method for the evaluation of theoretical photoelectron fluxes in the upper atmosphere resulting from the solar radiation at 304 A is presented. The calculation is based on considerations of primary and cascade (secondary) photoelectron production in the two-stream model, where photoelectron transport is described by two electron streams, one moving up and one moving down, and of loss rates due to collisions with neutral gases and thermal electrons. The calculation is illustrated for the case of photoelectrons at an energy of 24.5 eV, and it is noted that the 24.5-eV photoelectron flux may be used to monitor variations in the solar 304 A flux. Theoretical calculations based on various ionization and excitation cross sections of Banks et al. (1974) are shown to be in generally good agreement with AE-E measurements taken between 200 and 235 km, however the use of more recent, larger cross sections leads to photoelectron values a factor of two smaller than observations but in agreement with previous calculations. It is concluded that a final resolution of the photoelectron problem may depend on a reevaluation of the inelastic electron collision cross sections.

Polarization and wavelength diversities of Gulf Stream fronts imaged by AIRSAR

NASA Technical Reports Server (NTRS)

Lee, J. S.; Jansen, R. W.; Marmorino, G. O.; Chubb, S. R.

1995-01-01

During the 1990 Gulf Stream Experiment, NASA/JPL AIRSAR imaged the north edge of the Gulf Stream near the coast of Virginia. Simultaneous in-situ measurements of currents, temperatures, salinities, etc. were made for several crossings of the north edge by the R/V Cape Henlopen. Measurements identified two fronts with shearing and converging flows. The polarimetric SAR images from the fronts showed two bright linear features. One of them corresponds to the temperature front, which separated the warm Gulf Stream water to the south from a cool, freshwater filament to the north. The other line, located about 8 km north of the temperature front, is believed to correspond to the velocity front between the filament and the slope water. At these fronts, wave-current interactions produced narrow bands of steep and breaking waves manifesting higher radar returns in polarimetric SAR images. In general, our AIRSAR imagery shows that the signal-to-clutter ratio of radar cross sections for the temperature front is higher than that of the velocity front. In this paper, we study the polarization and wavelength diversities of radar response of these two fronts using the P-, L-, and C-Band Polarimetric SAR data. The north-south flight path of the AIRSAR crossed the temperature front several times and provided valuable data for analysis. Three individual passes are investigated. We found that for the temperature front, the cross-pol (HV) responses are much higher than co-pol responses (VV and HH), and that P-Band HV has the highest signal to clutter ratio. For the velocity front, the ratio is the strongest in P-Band VV, and it is indistinguishable for all polarizations in C-Band. The radar cross sections for all three polarization (HH, HV, and VV) and for all three bands are modelled using an ocean wave model and a composite Bragg scattering model. In our initial investigations, the theoretical model agrees qualitatively with the AIRSAR observations.

Experimental aerodynamics characteristics for bodies of elliptic cross section at angles of attack from 0 deg to 58 deg and Mach numbers from 0.6 to 2.0

NASA Technical Reports Server (NTRS)

Jorgensen, L. H.; Nelson, E. R.

1975-01-01

An experimental investigation was conducted to measure the static aerodynamic characteristics for two bodies of elliptic cross section and for their equivalent body of revolution. The equivalent body of revolution had the same length and axial distribution of cross-sectional area as the elliptic bodies. It consisted of a tangent ogive nose of fineness ratio 3 followed by a cylinder with a fineness ratio of 7. All bodies were tested at Mach numbers of 0.6, 0.9, 1.2, 1.5, and 2.0 at angles of attack from 0 deg to 58 deg. The data demonstrate that the aerodynamic characteristics can be significantly altered by changing the body cross section from circular to elliptic and by rolling the body from 0 deg to 90 deg. For example, the first elliptic body (with a constant cross-sectional axis ratio of 2) developed at zero roll about twice the normal force developed by the equivalent body of revolution. At some angles of attack greater than about 25 deg, side forces and yawing moments were measured in spite of the fact that the bodies were tested at zero angle of sideslip. The side-force and yawing-moment coefficients decreased with an increase in Mach number and essentially disappeared for all the bodies at Mach numbers greater than 1.2. From the standpoint of reducing undesirable side forces at high angles of attack, it is best to have the flattest side of the nose of the elliptic bodies pitching against the stream crossflow. The effect of Reynolds number was also the least significant for both elliptic bodies when the flattest side of the nose was pitched against the stream crossflow.

Influences of high-flow events on a stream channel altered by construction of a highway bridge: A case study

USGS Publications Warehouse

Hedrick, Lara B.; Welsh, Stuart A.; Anderson, James T.

2009-01-01

Impacts of highway construction on streams in the central Appalachians are a growing concern as new roads are created to promote tourism and economic development in the area. Alterations to the streambed of a first-order stream, Sauerkraut Run, Hardy County, WV, during construction of a highway overpass included placement and removal of a temporary culvert, straightening and regrading of a section of stream channel, and armourment of a bank with a reinforced gravel berm. We surveyed longitudinal profiles and cross sections in a reference reach and the altered reach of Sauerkraut Run from 2003 through 2007 to measure physical changes in the streambed. During the four-year period, three high-flow events changed the streambed downstream of construction including channel widening and aggradation and then degradation of the streambed. Upstream of construction, at a reinforced gravel berm, bank erosion was documented. The reference section remained relatively unchanged. Knowledge gained by documenting channel changes in response to natural and anthropogenic variables can be useful for managers and engineers involved in highway construction projects.

Drainage networks after wildfire

USGS Publications Warehouse

Kinner, D.A.; Moody, J.A.

2005-01-01

Predicting runoff and erosion from watersheds burned by wildfires requires an understanding of the three-dimensional structure of both hillslope and channel drainage networks. We investigate the small-and large-scale structures of drainage networks using field studies and computer analysis of 30-m digital elevation model. Topologic variables were derived from a composite 30-m DEM, which included 14 order 6 watersheds within the Pikes Peak batholith. Both topologic and hydraulic variables were measured in the field in two smaller burned watersheds (3.7 and 7.0 hectares) located within one of the order 6 watersheds burned by the 1996 Buffalo Creek Fire in Central Colorado. Horton ratios of topologic variables (stream number, drainage area, stream length, and stream slope) for small-scale and large-scale watersheds are shown to scale geometrically with stream order (i.e., to be scale invariant). However, the ratios derived for the large-scale drainage networks could not be used to predict the rill and gully drainage network structure. Hydraulic variables (width, depth, cross-sectional area, and bed roughness) for small-scale drainage networks were found to be scale invariant across 3 to 4 stream orders. The relation between hydraulic radius and cross-sectional area is similar for rills and gullies, suggesting that their geometry can be treated similarly in hydraulic modeling. Additionally, the rills and gullies have relatively small width-to-depth ratios, implying sidewall friction may be important to the erosion and evolutionary process relative to main stem channels.

ENHANCING HSPF MODEL CHANNEL HYDRAULIC REPRESENTATION

EPA Science Inventory

The Hydrological Simulation Program - FORTRAN (HSPF) is a comprehensive watershed model, which employs depth-area-volume-flow relationships known as hydraulic function table (FTABLE) to represent stream channel cross-sections and reservoirs. An accurate FTABLE determination for a...

An analysis of stream channel cross section technique as a means to determine anthropogenic change in second order streams at the Tenderfoot Creek Experimental Forest, Meagher County, Montana

Treesearch

Jeff Boice

1999-01-01

Five second order tributaries to Tenderfoot Creek were investigated: Upper Tenderfoot Creek, Sun Creek, Spring Park Creek, Bubbling Creek, and Stringer Creek. Second order reaches were initially located on 7.5 minute topographic maps using techniques first applied by Strahler (1952). Reach breaks were determined in the field through visual inspection. Vegetation type (...

Remote sensing of channels and riparian zones with a narrow-beam aquatic-terrestrial LIDAR

Treesearch

Jim McKean; Dave Nagel; Daniele Tonina; Philip Bailey; Charles Wayne Wright; Carolyn Bohn; Amar Nayegandhi

2009-01-01

The high-resolution Experimental Advanced Airborne Research LIDAR (EAARL) is a new technology for cross-environment surveys of channels and floodplains. EAARL measurements of basic channel geometry, such as wetted cross-sectional area, are within a few percent of those from control field surveys. The largest channel mapping errors are along stream banks. The LIDAR data...

Impact of sampling techniques on measured stormwater quality data for small streams

USGS Publications Warehouse

Harmel, R.D.; Slade, R.M.; Haney, R.L.

2010-01-01

Science-based sampling methodologies are needed to enhance water quality characterization for setting appropriate water quality standards, developing Total Maximum Daily Loads, and managing nonpoint source pollution. Storm event sampling, which is vital for adequate assessment of water quality in small (wadeable) streams, is typically conducted by manual grab or integrated sampling or with an automated sampler. Although it is typically assumed that samples from a single point adequately represent mean cross-sectional concentrations, especially for dissolved constituents, this assumption of well-mixed conditions has received limited evaluation. Similarly, the impact of temporal (within-storm) concentration variability is rarely considered. Therefore, this study evaluated differences in stormwater quality measured in small streams with several common sampling techniques, which in essence evaluated within-channel and within-storm concentration variability. Constituent concentrations from manual grab samples and from integrated samples were compared for 31 events, then concentrations were also compared for seven events with automated sample collection. Comparison of sampling techniques indicated varying degrees of concentration variability within channel cross sections for both dissolved and particulate constituents, which is contrary to common assumptions of substantial variability in particulate concentrations and of minimal variability in dissolved concentrations. Results also indicated the potential for substantial within-storm (temporal) concentration variability for both dissolved and particulate constituents. Thus, failing to account for potential cross-sectional and temporal concentration variability in stormwater monitoring projects can introduce additional uncertainty in measured water quality data. Copyright ?? 2010 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

ENHANCING HYDROLOGICAL SIMULATION PROGRAM - FORTRAN MODEL CHANNEL HYDRAULIC REPRESENTATION

EPA Science Inventory

The Hydrological Simulation Program– FORTRAN (HSPF) is a comprehensive watershed model that employs depth-area - volume - flow relationships known as the hydraulic function table (FTABLE) to represent the hydraulic characteristics of stream channel cross-sections and reservoirs. ...

Gravel Transport Measured With Bedload Traps in Mountain Streams: Field Data Sets to be Published

NASA Astrophysics Data System (ADS)

Bunte, K.; Swingle, K. W.; Abt, S. R.; Ettema, R.; Cenderelli, D. A.

2017-12-01

Direct, accurate measurements of coarse bedload transport exist for only a few streams worldwide, because the task is laborious and requires a suitable device. However, sets of accurate field data would be useful for reference with unsampled sites and as a basis for model developments. The authors have carefully measured gravel transport and are compiling their data sets for publication. To ensure accurate measurements of gravel bedload in wadeable flow, the designed instrument consisted of an unflared aluminum frame (0.3 x 0.2 m) large enough for entry of cobbles. The attached 1 m or longer net with a 4 mm mesh held large bedload volumes. The frame was strapped onto a ground plate anchored onto the channel bed. This setup avoided involuntary sampler particle pick-up and enabled long sampling times, integrating over fluctuating transport. Beveled plates and frames facilitated easy particle entry. Accelerating flow over smooth plates compensated for deceleration within the net. Spacing multiple frames by 1 m enabled sampling much of the stream width. Long deployment, and storage of sampled bedload away from the frame's entrance, were attributes of traps rather than samplers; hence the name "bedload traps". The authors measured gravel transport with 4-6 bedload traps per cross-section at 10 mountain streams in CO, WY, and OR, accumulating 14 data sets (>1,350 samples). In 10 data sets, measurements covered much of the snowmelt high-flow season yielding 50-200 samples. Measurement time was typically 1 hour but ranged from 3 minutes to 3 hours, depending on transport intensity. Measuring back-to-back provided 6 to 10 samples over a 6 to 10-hour field day. Bedload transport was also measured with a 3-inch Helley-Smith sampler. The data set provides fractional (0.5 phi) transport rates in terms of particle mass and number for each bedload trap in the cross-section, the largest particle size, as well as total cross-sectional gravel transport rates. Ancillary field data include stage, discharge, long-term flow records if available, surface and subsurface sediment sizes, as well as longitudinal and cross-sectional site surveys. Besides transport relations, incipient motion conditions, hysteresis, and lateral variation, the data provide a reliable modeling basis to test insights and hypotheses regarding bedload transport.

Flow in out-of-plane double S-bonds

NASA Technical Reports Server (NTRS)

Schmidt, M. C.; Whitelaw, J. H.; Yianneskis, M.

1986-01-01

Developing flows in two out-of-plane double S-bend configurations have been measured by laser-Doppler anemometry. The first duct had a rectangular cross-section 40mmx40mm at the inlet and consisted of a uniform area 22.5 deg. - 22.5 deg. S-duct upstream with a 22.5 deg.- 22.5 deg. S- diffuser downstream. The second duct had a circular cross-section and consisted of a 45 deg. - 45 deg. uniform area S-duct upstream with a 22.5 deg. -22.5 deg. S-diffuser downstream. In both configurations the ratio of the mean radius of curvature to the inlet hydraulic diameter was 7.0, the exit-to-inlet area ratio of the diffusers was 1.5 and the ducts were connected so that the centerline of the S-duct lay in a plane normal to that of the S-diffuser. Streamwise and cross-stream velocity components were measured in laminar flow for the rectangular duct and in turbulent flow for both configurations; measurements of the turbulence levels, cross-correlations and wall static pressures were also made in the turbulent flow cases. Secondary flows of the first kind are present in the first S-duct and they are complemented or counteracted by the secondary flows generated by the area expansion and by the curvature of the S-diffusers downstream. Cross-stream velocities with magnitudes up to 0.19 and 0.11 of the bulk velocity were measured in the laminar and turbulent flows respectively in the rectangular duct and six cross-flow vortices were evident at the exit of the duct in both flow cases. The turbulent flow in the circular duct was qualitatively similar to that in the rectangular configuration, but the cross-stream velocities measured at the exit plane were smaller in the circular geometry. The results are presented in sufficient detail and accuracy for the assessment of numerical calculation methods and are listed in tabular form for this purpose.

Predicting changes in hydrologic retention in an evolving semi-arid alluvial stream

USGS Publications Warehouse

Harvey, J.W.; Conklin, M.H.; Koelsch, R.S.

2003-01-01

Hydrologic retention of solutes in hyporheic zones or other slowly moving waters of natural channels is thought to be a significant control on biogeochemical cycling and ecology of streams. To learn more about factors affecting hydrologic retention, we repeated stream-tracer injections for 5 years in a semi-arid alluvial stream (Pinal Creek, Ariz.) during a period when streamflow was decreasing, channel width increasing, and coverage of aquatic macrophytes expanding. Average stream velocity at Pinal Creek decreased from 0.8 to 0.2 m/s, average stream depth decreased from 0.09 to 0.04 m, and average channel width expanded from 3 to 13 m. Modeling of tracer experiments indicated that the hydrologic retention factor (Rh), a measure of the average time that solute spends in storage per unit length of downstream transport, increased from 0.02 to 8 s/m. At the same time the ratio of cross-sectional area of storage zones to main channel cross-sectional area (As/A) increased from 0.2 to 0.8 m2/m2, and average water residence time in storage zones (ts) increased from 5 to 24 min. Compared with published data from four other streams in the US, Pinal Creek experienced the greatest change in hydrologic retention for a given change in streamflow. The other streams differed from Pinal Creek in that they experienced a change in streamflow between tracer experiments without substantial geomorphic or vegetative adjustments. As a result, a regression of hydrologic retention on streamflow developed for the other streams underpredicted the measured increases in hydrologic retention at Pinal Creek. The increase in hydrologic retention at Pinal Creek was more accurately predicted when measurements of the Darcy-Weisbach friction factor were used (either alone or in addition to streamflow) as a predictor variable. We conclude that relatively simple measurements of channel friction are useful for predicting the response of hydrologic retention in streams to major adjustments in channel morphology as well as changes in streamflow. Published by Elsevier Ltd.

Ku-band ocean radar backscatter observations during SWADE

NASA Technical Reports Server (NTRS)

Nghiem, S. V.; Li, F. K.; Lou, S. H.; Neumann, G.

1993-01-01

We present results obtained by an airborne Ku-band scatterometer during the Surface Wave Dynamics Experiment (SWADE). The specific objective of this study is to improve our understanding of the relationship between ocean radar backscatter and near surface winds. The airborne scatterometer, NUSCAT, was flown on the NASA Ames C-130 over an instrumented oceanic area near 37 deg N and 74 deg W. A total of 10 flights from 27 Feb. to 9 Mar. 1991 were conducted. Radar backscatter at incidence angles of 0 to 60 deg were obtained. For each incidence angle, the NUSCAT antenna was azimuthally scanned in multiple complete circles to measure the azimuthal backscatter modulations. Both horizontal and vertical polarization backscatter measurements were made. In some of the flights, the cross-polarization backscatter was measured as well. Internal calibrations were carried out throughout each of the flights. Preliminary results indicate that the radar was stable to +/-0.3 dB for each flight. In this paper, we present studies of the backscatter measurements over several crossings of the Gulf Stream. In these crossings, large air-sea temperature differences were encountered and substantial changes in the radar cross section were observed. We summarize the observations and compare them to the changes of several wind variables across the Gulf Stream boundary. In one of the flights, the apparent wind near the cold side of the Gulf Stream was very low (less than 3 m/s). The behavior of the radar cross sections at such low wind speeds and a comparison with models are presented. A case study of the effects of swell on the absolute cross section and the azimuthal modulation pattern is presented. Significant wave heights larger than m were observed during SWADE. The experimentally observed effects of the swell on the radar backscatter are discussed. The effects are used to assess the uncertainties in wind retrieval due to underlying waves. A summary of azimuthal modulation from our ten-flight of NUSCAT data is given. Wind velocities, air and sea surface temperature, ocean spectrum, and other variables measured from aircraft and buoys are also shown.

GSTARS computer models and their applications, part I: theoretical development

USGS Publications Warehouse

Yang, C.T.; Simoes, F.J.M.

2008-01-01

GSTARS is a series of computer models developed by the U.S. Bureau of Reclamation for alluvial river and reservoir sedimentation studies while the authors were employed by that agency. The first version of GSTARS was released in 1986 using Fortran IV for mainframe computers. GSTARS 2.0 was released in 1998 for personal computer application with most of the code in the original GSTARS revised, improved, and expanded using Fortran IV/77. GSTARS 2.1 is an improved and revised GSTARS 2.0 with graphical user interface. The unique features of all GSTARS models are the conjunctive use of the stream tube concept and of the minimum stream power theory. The application of minimum stream power theory allows the determination of optimum channel geometry with variable channel width and cross-sectional shape. The use of the stream tube concept enables the simulation of river hydraulics using one-dimensional numerical solutions to obtain a semi-two- dimensional presentation of the hydraulic conditions along and across an alluvial channel. According to the stream tube concept, no water or sediment particles can cross the walls of stream tubes, which is valid for many natural rivers. At and near sharp bends, however, sediment particles may cross the boundaries of stream tubes. GSTARS3, based on FORTRAN 90/95, addresses this phenomenon and further expands the capabilities of GSTARS 2.1 for cohesive and non-cohesive sediment transport in rivers and reservoirs. This paper presents the concepts, methods, and techniques used to develop the GSTARS series of computer models, especially GSTARS3. ?? 2008 International Research and Training Centre on Erosion and Sedimentation and the World Association for Sedimentation and Erosion Research.

Bankfull discharge and channel characteristics of streams in New York State

USGS Publications Warehouse

Mulvihill, Christiane I.; Baldigo, Barry P.; Miller, Sarah J.; DeKoskie, Douglas; DuBois, Joel

2009-01-01

Equations that relate drainage area to bankfull discharge and channel characteristics (such as width, depth, and cross-sectional area) at gaged sites are needed to help define bankfull discharge and channel characteristics at ungaged sites and can be used in stream-restoration and protection projects, stream-channel classification, and channel assessments. These equations are intended to serve as a guide for streams in areas of similar hydrologic, climatic, and physiographic conditions. New York State contains eight hydrologic regions that were previously delineated on the basis of high-flow (flood) characteristics. This report seeks to increase understanding of the factors affecting bankfull discharge and channel characteristics to drainage-area size relations in New York State by providing an in-depth analysis of seven previously published regional bankfull-discharge and channel-characteristics curves.Stream-survey data and discharge records from 281 cross sections at 82 streamflow-gaging stations were used in regression analyses to relate drainage area to bankfull discharge and bankfull-channel width, depth, and cross-sectional area. The R2 and standard errors of estimate of each regional equation were compared to the R2 and standard errors of estimate for the statewide (pooled) model to determine if regionalizing data reduced model variability. It was found that regional models typically yield less variable results than those obtained using pooled statewide equations, which indicates statistically significant regional differences in bankfull-discharge and channel-characteristics relations.Statistical analysis of bankfull-discharge relations found that curves for regions 4 and 7 fell outside the 95-percent confidence interval bands of the statewide model and had intercepts that were significantly diferent (p≤0.10) from the other five hydrologic regions.Analysis of channel-characteristics relations found that the bankfull width, depth, and cross-sectional area curves for region 3 were significantly different p(≤0.05) from the other six regions.It was hypothesized that some regional variability could be reduced by creating models for streams with similar physiographic and climatic characteristics. Available data on streamflow patterns and previous regional-curve research suggested that mean annual runoff, Rosgen stream type, and water-surface slope were the variables most likely to influence regional bankfull discharge and channel characteristics to drainage-area size relations. Results showed that although all of these factors had an influence on regional relations, most stratified models have lower 2 values and higher standard errors of estimate than the regional models.The New York statewide (pooled) bankfull-discharge equation and equations for regions 4 and 7 were compared with equations for four other regions in the Northeast to evaluate region-to-region differences, and assess the ability of individual curves to produce results more accurate than those that would be obtained from one model of the northeastern United States. Results indicated that model slopes lack significant diferences, though intercepts are significantly different. Comparison of bankfull-discharge estimates using different models shows that results could vary by as much as 100 percent depending on which model was used and indicated that regionalization improved model accuracy.

Riparian vegetation controls on the hydraulic geometry of streams

NASA Astrophysics Data System (ADS)

McBride, M.

2010-12-01

A synthesis of field measurements, remote observations, and numerical modeling techniques highlights the significance of riparian vegetation in determining the geometry of streams and impacting sediment transport dynamics in temperate, Piedmont regions. Specifically, forested and grassy riparian vegetation establish streams with significantly different widths and with different timescales for attaining a state of dynamic equilibrium. The interactions between riparian vegetation, channel form, and channel dynamics are scale dependent. Scale dependency arises because of variations in ratios of vegetation length scales and geomorphic scales (e.g., channel width and depth). Stream reaches with grassy vegetation experience more frequent overbank discharges, migrate more quickly, and exhibit a more classic dynamic equilibrium than forested reaches. These phenomena are relevant to current watershed management efforts that aim to reduce sediment and nutrient loads to receiving water bodies, such as the Chesapeake Bay. The reforestation of riparian buffers is a common restoration technique that intends to improve water quality, temperature regimes, and in-stream physical habitat. Passive reforestation of riparian areas along a tributary to Sleepers River in Danville, VT, USA caused an increase in channel width and cross-sectional area over a 40-year period. From a comparison of historical records and current cross-sectional dimensions, the channel widening resulted in the mobilization of approximately 85 kg/ha/yr of floodplain sediments. Long-term monitoring of suspended sediments in an adjacent watershed indicates that this sediment source may account for roughly 40 percent of the total suspended sediment load. In some instances, increased sediment loads associated with channel widening may be an unforeseen consequence that compromises riparian restoration efforts.

Sediment deposition from forest roads at stream crossings as influenced by road characteristics

Treesearch

A.J. Lang; W.M. Aust; M.C. Bolding; K.J. McGuire

2015-01-01

Recent controversies associated with ditched forest roads and stream crossings in the Pacific Northwest have focused national attention on sediment production and best management practices (BMPs) at stream crossings. Few studies have quantified soil erosion rates at stream crossings as influenced by road characteristics and compared them to modeled rates. Soil erosion...

Forestry best management practices and sediment control at skidder stream crossings

Treesearch

Laura R. Wear; W. Michael Aust; M. Chad Bolding; Brian D. Strahm; Andrew C. Dolloff

2015-01-01

Stream crossings for skid trails have high sediment delivery ratios. Forestry Best Management Practices (BMPs) have proven to be effective for erosion control, but few studies have quantified the impact of various levels of BMPs on sedimentation. In this study, three skid-trail stream-crossing BMP treatments were installed on nine operational stream crossings (three...

Get In and Get Out: Assessing Stream Sediment Loading from Short Duration Forest Harvest Operations and Rapid Haul Road Decommissioning.

NASA Astrophysics Data System (ADS)

Corrigan, A.; Silins, U.; Stone, M.

2016-12-01

Best management practices (BMPs) and associated erosion control measures for mitigating sediment impacts from forestry roads and road-stream crossings are well documented. While rapid road decommissioning after forestry operations may serve to limit broader impacts on sediment production in high value headwater streams, few studies have evaluated the combined effects of accelerated harvest operations and rapid retirement of logging roads and road-stream crossings on stream sediment. The objectives of this study were to evaluate the initial impacts of these strategies on fine sediment loading and fate during a short duration harvesting operation in 3 headwater sub-catchments in the southwestern Rocky Mountains of Alberta, Canada. A multi-pronged sampling approach (ISCOs, event focused grab sampling, continuous wash load sampling, and stream bed sediment intrusion measurements) was used to measure sediment loading and deposition in streambeds upstream and downstream of road-stream bridge crossings during harvest operations (2015) and after road and bridge crossing retirement (2016). Sediment production from forestry roads was generally much lower than has been reported from other studies in similar settings. Average total suspended solids (TSS) downstream of the bridge crossings were actually lower (-3.28 g/L; -0.704 g/L) than upstream of two bridge crossings while in-stream sediment sources contributed to elevated sediment downstream of a third road-stream crossing. Minimal in stream sediment impacts from forest harvest and road-stream crossings was likely a reflection of combined factors including a) employment of erosion control BMPs to roads and bridge crossings, b) rapid decommissioning of roads and crossings to limit exposure of linear land disturbance features, and c) drier El Niño climatic conditions during the study.

Predicting Vulnerability of the Integrity and Connectivity Associated with Culverts in Low Order Streams of Northern Michigan

NASA Astrophysics Data System (ADS)

King, C. H.; Wagenbrenner, J.; Fedora, M.; Watkins, D.; Watkins, M. K.; Huckins, C.

2017-12-01

The Great Lakes Region of North America has experienced more frequent extreme precipitation events in recent decades, resulting in a large number of stream crossing failures. While there are accepted methods for designing stream crossings to accommodate peak storm discharges, less attention has been paid to assessing the risk of failure. To evaluate failure risk and potential impacts, coarse-resolution stream crossing surveys were completed on 51 stream crossings and dams in the North Branch Paint River watershed in Michigan's Upper Peninsula. These inventories determined stream crossing dimensions along with stream and watershed characteristics. Eleven culverts were selected from the coarse surveys for high resolution hydraulic analysis to estimate discharge conditions expected at crossing failure. Watershed attributes upstream of the crossing, including area, slope, and storage, were acquired. Sediment discharge and the economic impact associated with a failure event were also estimated for each stream crossing. Impacts to stream connectivity and fish passability were assessed from the coarse-level surveys. Using information from both the coarse and high-resolution surveys, we also developed indicators to predict failure risk without the need for complex hydraulic modeling. These passability scores and failure risk indicators will help to prioritize infrastructure replacement and improve the overall connectivity of river systems throughout the upper Great Lakes Region.

User's manual for the Graphical Constituent Loading Analysis System (GCLAS)

USGS Publications Warehouse

Koltun, G.F.; Eberle, Michael; Gray, J.R.; Glysson, G.D.

2006-01-01

This manual describes the Graphical Constituent Loading Analysis System (GCLAS), an interactive cross-platform program for computing the mass (load) and average concentration of a constituent that is transported in stream water over a period of time. GCLAS computes loads as a function of an equal-interval streamflow time series and an equal- or unequal-interval time series of constituent concentrations. The constituent-concentration time series may be composed of measured concentrations or a combination of measured and estimated concentrations. GCLAS is not intended for use in situations where concentration data (or an appropriate surrogate) are collected infrequently or where an appreciable amount of the concentration values are censored. It is assumed that the constituent-concentration time series used by GCLAS adequately represents the true time-varying concentration. Commonly, measured constituent concentrations are collected at a frequency that is less than ideal (from a load-computation standpoint), so estimated concentrations must be inserted in the time series to better approximate the expected chemograph. GCLAS provides tools to facilitate estimation and entry of instantaneous concentrations for that purpose. Water-quality samples collected for load computation frequently are collected in a single vertical or at single point in a stream cross section. Several factors, some of which may vary as a function of time and (or) streamflow, can affect whether the sample concentrations are representative of the mean concentration in the cross section. GCLAS provides tools to aid the analyst in assessing whether concentrations in samples collected in a single vertical or at single point in a stream cross section exhibit systematic bias with respect to the mean concentrations. In cases where bias is evident, the analyst can construct coefficient relations in GCLAS to reduce or eliminate the observed bias. GCLAS can export load and concentration data in formats suitable for entry into the U.S. Geological Survey's National Water Information System. GCLAS can also import and export data in formats that are compatible with various commonly used spreadsheet and statistics programs.

13. WAIKOLU STREAM CROSSING NO. 1, FIRST CROSSING OF WAIKOLU ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

13. WAIKOLU STREAM CROSSING NO. 1, FIRST CROSSING OF WAIKOLU STREAM, VIEW UPSTREAM. CONSTRUCTED OF CONCRETE AND RUBBLE MASONRY, PIPELINE IS ENCASED WITHIN. - Kalaupapa Water Supply System, Waikolu Valley to Kalaupapa Settlement, Island of Molokai, Kalaupapa, Kalawao County, HI

Single channel atmospheric pressure transporting plasma and plasma stream demultiplexing: physical characterization and application to E. coli bacteria inactivation

NASA Astrophysics Data System (ADS)

Valinataj Omran, A.; Sohbatzadeh, F.; Siadati, S. N.; Hosseinzadeh Colagar, A.; Akishev, Y.; Arefi-Khonsari, F.

2017-08-01

In this article, we developed transporting plasma sources that operate at atmospheric pressure. The effect of electrode configuration on plasma transporting was investigated. In order to increase the transporting plasma cross-section, we converted a plasma stream into four plasma channels by a cylindrical housing. Electron excitation and rotational temperatures were estimated using optical emission spectroscopy. Furthermore, the electrical and temporal characteristics of the plasma, discharge power and charge deposition on the target were investigated. The propagation characteristics of single and multi-channel transporting plasma were compared with the same cross-sectional area. Two configurations for multi-channels were designed for this purpose. Escherichia coli bacteria were exposed to the single and multi-channel transporting discharge for different time durations. After exposure, the results indicated that the inactivation zones were significantly increased by a multi-channel transporting plasma. Finally, E. coli inactivation by those plasma apparatuses was compared with that of several standard antimicrobial test discs such as Gentamicin, Tetracycline, Amoxicillin and Cefixime.

Stream chemistry and groundwater-surface water interactions in Piedmont headwater streams (Charlotte, NC) prior to whole-watershed restoration

NASA Astrophysics Data System (ADS)

Vinson, D. S.; Allison, N.; Haydin, D.; Kiker, T.; Starnes, C.; Wickliff, E.; McMillan, S.; Clinton, S. M.

2017-12-01

While restoration is an established practice in urban streams, pre/post restoration hyporheic function and its potential role in nutrient processing is less well studied and understood. Here we report results from a pre-restoration sampling period in the 6.5 km2 headwaters of the Reedy Creek (RC) watershed, an urban forest stream in Charlotte, NC at the divide between the Catawba and Pee Dee river systems. Whole-watershed restoration of this deeply incised stream is scheduled to begin in fall 2017. To characterize the pre-restoration baseline condition, nutrients, DOC, temperature, and other biogeochemical parameters were analyzed quarterly from RC and 11 tributaries since 2014 and weekly since mid-2016. Riparian groundwater from 10 shallow wells has been analyzed quarterly since 2014. Nutrient concentrations vary among land uses. For example, median stream nitrate concentrations range from <0.1 mg/L as N in the undeveloped tributary to 2.5 mg/L as N in an agriculture-influenced tributary, and 0.2 mg/L as N at the RC outlet. As with nutrients, major ions, specific UV absorbance, and alkalinity vary among tributary watershed land uses. Riparian well and stream levels collected every 15 min since 2013 at 5 cross-sections indicate prevailing hydraulic gradients from the wells to the channel. At all 5 cross-sections, high stream flow events coincide with high groundwater levels, possibly indicating direct recharge to the aquifer by rain events, rather than large-scale recharge by the stream itself. Vertical hydraulic gradient measurements, slug tests, and radon-222 measurements were made at 25-75 cm deep sub-streambed piezometers. Radon-222 activities of piezometers (29-707 pCi/L; median=120 pCi/L, n=7) cover a larger range than either well water (170-647 pCi/L; median 268 pCi/L; n=7) or stream water (12-37 pCi/L, median 25 pCi/L; n=5), consistent with limited hyporheic mixing. Streambed hydraulic conductivity is requisite for significant exchange (e.g. low-K clay-rich saprolite to high-K sand and gravel are found in short stream reaches). Limited shallow downwelling may occur where the vertical hydraulic gradient and bed particle size are suitable. These results will be utilized to understand the pre- and post- restoration function of forested headwater systems in urban watersheds.

Load-based approaches for modelling visual clarity in streams at regional scale.

PubMed

Elliott, A H; Davies-Colley, R J; Parshotam, A; Ballantine, D

2013-01-01

Reduction of visual clarity in streams by diffuse sources of fine sediment is a cause of water quality impairment in New Zealand and internationally. In this paper we introduce the concept of a load of optical cross section (LOCS), which can be used for load-based management of light-attenuating substances and for water quality models that are based on mass accounting. In this approach, the beam attenuation coefficient (units of m(-1)) is estimated from the inverse of the visual clarity (units of m) measured with a black disc. This beam attenuation coefficient can also be considered as an optical cross section (OCS) per volume of water, analogous to a concentration. The instantaneous 'flux' of cross section is obtained from the attenuation coefficient multiplied by the water discharge, and this can be accumulated over time to give an accumulated 'load' of cross section (LOCS). Moreover, OCS is a conservative quantity, in the sense that the OCS of two combined water volumes is the sum of the OCS of the individual water volumes (barring effects such as coagulation, settling, or sorption). The LOCS can be calculated for a water quality station using rating curve methods applied to measured time series of visual clarity and flow. This approach was applied to the sites in New Zealand's National Rivers Water Quality Network (NRWQN). Although the attenuation coefficient follows roughly a power relation with flow at some sites, more flexible loess rating curves are required at other sites. The hybrid mechanistic-statistical catchment model SPARROW (SPAtially Referenced Regressions On Watershed attributes), which is based on a mass balance for mean annual load, was then applied to the NRWQN dataset. Preliminary results from this model are presented, highlighting the importance of factors related to erosion, such as rainfall, slope, hardness of catchment rock types, and the influence of pastoral development on the load of optical cross section.

Microstreaming from Sessile Semicylindrical Bubbles

NASA Astrophysics Data System (ADS)

Hilgenfeldt, Sascha; Rallabandi, Bhargav; Guo, Lin; Wang, Cheng

2014-03-01

Powerful steady streaming flows result from the ultrasonic driving of microbubbles, in particular when these bubbles have semicylindrical cross section and are positioned in contact with a microfluidic channel wall. We have used this streaming in experiment to develop novel methods for trapping and sorting of microparticles by size, as well as for micromixing. Theoretically, we arrive at an analytical description of the streaming flow field through an asymptotic computation that, for the first time, reconciles the boundary layers around the bubble and along the substrate wall, and also takes into account the oscillation modes of the bubble. This approach gives insight into changes in the streaming pattern with bubble size and driving frequency, including a reversal of the flow direction at high frequencies with potentially useful applications. Present address: Mechanical and Aerospace Engineering, Missouri S &T.

Streamflow loss quantification for groundwater flow modeling using a wading-rod-mounted acoustic Doppler current profiler in a headwater stream

NASA Astrophysics Data System (ADS)

Pflügl, Christian; Hoehn, Philipp; Hofmann, Thilo

2017-04-01

Irrespective of the availability of various field measurement and modeling approaches, the quantification of interactions between surface water and groundwater systems remains associated with high uncertainty. Such uncertainties on stream-aquifer interaction have a high potential to misinterpret the local water budget and water quality significantly. Due to typically considerable temporal variation of stream discharge rates, it is desirable for the measurement of streamflow to reduce the measuring duration while reducing uncertainty. Streamflow measurements, according to the velocity-area method, have been performed along reaches of a losing-disconnected, subalpine headwater stream using a 2-dimensional, wading-rod-mounted acoustic Doppler current profiler (ADCP). The method was chosen, with stream morphology not allowing for boat-mounted setups, to reduce uncertainty compared to conventional, single-point streamflow measurements of similar measurement duration. Reach-averaged stream loss rates were subsequently quantified between 12 cross sections. They enabled the delineation of strongly infiltrating stream reaches and their differentiation from insignificantly infiltrating reaches. Furthermore, a total of 10 near-stream observation wells were constructed and/or equipped with pressure and temperature loggers. The time series of near-stream groundwater temperature data were cross-correlated with stream temperature time series to yield supportive qualitative information on the delineation of infiltrating reaches. Subsequently, as a reference parameterization, the hydraulic conductivity and specific yield of a numerical, steady-state model of groundwater flow, in the unconfined glaciofluvial aquifer adjacent to the stream, were inversely determined incorporating the inferred stream loss rates. Applying synthetic sets of infiltration rates, resembling increasing levels of uncertainty associated with single-point streamflow measurements of comparable duration, the same inversion procedure was run. The volume-weighted mean of the respective parameter distribution within 200 m of stream periphery deviated increasingly from the reference parameterization at increasing deviation of infiltration rates.

Method and apparatus for obtaining enhanced production rate of thermal chemical reactions

DOEpatents

Tonkovich, Anna Lee Y [Pasco, WA; Wang, Yong [Richland, WA; Wegeng, Robert S [Richland, WA; Gao, Yufei [Kennewick, WA

2003-04-01

The present invention is a method and apparatus (vessel) for providing a heat transfer rate from a reaction chamber through a wall to a heat transfer chamber substantially matching a local heat transfer rate of a catalytic thermal chemical reaction. The key to the invention is a thermal distance defined on a cross sectional plane through the vessel inclusive of a heat transfer chamber, reaction chamber and a wall between the chambers. The cross sectional plane is perpendicular to a bulk flow direction of the reactant stream, and the thermal distance is a distance between a coolest position and a hottest position on the cross sectional plane. The thermal distance is of a length wherein the heat transfer rate from the reaction chamber to the heat transfer chamber substantially matches the local heat transfer rate.

Channel Geometry and Flood Flows: Quantifying over-bank flow dynamics during high-flow events in North Carolina's floodplains

NASA Astrophysics Data System (ADS)

Lovette, J. P.; Duncan, J. M.; Vimal, S.; Band, L. E.

2015-12-01

Natural riparian areas play numerous roles in the maintenance and improvement of stream water quality. Both restoration of riparian areas and improvement of hydrologic connectivity to the stream are often key goals of river restoration projects. These management actions are designed to improve nutrient removal by slowing and treating overland flow delivered from uplands and by storing, treating, and slowly releasing streamwater from overbank inundation during flood events. A major question is how effective this storage of overbank flow is at treating streamwater based on the cumulative time stream discharge at a downstream location has spent in shallower, slower overbank flow. The North Carolina Floodplain Mapping Program maintains a detailed statewide Flood Risk Information System (FRIS) using HEC-RAS modeling, lidar, and detailed surveyed river cross-sections. FRIS provides extensive information regarding channel geometry on approximately 39,000 stream reaches (a slightly coarser spatial resolution than the NHD+v2 dataset) with tens of cross-sections for each reach. We use this FRIS data to calculate volume and discharge from floodplain riparian areas separately from in-channel flow during overbank events. Preliminary results suggest that a small percentage of total annual discharge interacts with the full floodplain extent along a stream reach due to the infrequency of overbank flow events. However, with the significantly different physical characteristics of the riparian area when compared to the channel itself, this overbank flow can provide unique services to water quality. Our project aims to use this information in conjunction with data from the USGS SPARROW program to target non-point source hotspots of Nitrogen and Phosphorus addition and removal. By better understanding the flow dynamics within riparian areas during high flow events, riparian restoration projects can be carried out with improved efficacy.

Effectiveness of forestry BMPS for stream crossing sediment reduction using rainfall simulation

Treesearch

Brian C. Morris; M. Chad Bolding; W. Michael Aust

2015-01-01

Recent decisions by the United States Supreme Court and United States Environmental Protection Agency (EPA) have re-emphasized the importance of forestry best management practices (BMPs) at stream crossings. Stream crossings are potential major sources of sediment due to their direct connectivity between the potential erosion source and the stream, which eliminates...

Development of regional curves of bankfull-channel geometry and discharge for streams in the non-urban, Piedmont Physiographic Province, Pennsylvania and Maryland

USGS Publications Warehouse

Cinotto, Peter J.

2003-01-01

Stream-restoration projects utilizing natural stream designs frequently are based on the bankfull-channel characteristics of stream reaches that can accommodate streamflow and sediment transport without excessive erosion or deposition and lie within a watershed that has similar runoff characteristics. The bankfull channel at an ungaged impaired site or reference reach is identified by use of field indicators and is confirmed with tools such as regional curves. Channel dimensions were surveyed at 14 streamflow-measurement stations operated by the U.S. Geological Survey (USGS) in the Gettysburg-Newark Lowland Section, Piedmont Lowland Section, and the Piedmont Upland Section of the Piedmont Physiographic Province1 in Pennsylvania and Maryland. From the surveyed channel dimensions, regional curves were developed from regression analyses of the relations between drainage area and the cross-sectional area, mean depth, width, and streamflow of the bankfull channel at these sites. Bankfull cross-sectional area and bankfull discharge have the strongest relation to drainage area as evidenced by R2 values of 0.94 and 0.93, respectively. The relation between bankfull crosssectional area and drainage area has a p-value of less than 0.001; no p-value is presented for the relation between bankfull discharge and drainage area because of a non-normal residual distribution. The relation between bankfull width and drainage area has an R2 value of 0.80 and a p-value of less than 0.001 indicating a moderate linear relation between all stations. The relation between bankfull mean depth and drainage area, with an R2 value of 0.72 and a p-value of less than 0.001, also indicates a moderate linear relation between all stations. The concept of regional curves can be a valuable tool to support efforts in stream restoration. Practitioners of stream restoration need to recognize it as such and realize the limitations. The small number of USGS streamflow-measurement stations available for analysis is a major limiting factor in the strength of the results of this investigation, as is the inherent problem of directly associating streamflow-measurement station data to geomorphic analysis of a stream reach. Subjective selection criteria may have unnecessarily eliminated streamflow-measurement stations that could have been included in the regional curves and (or) added those that may belong within a different region. A bankfull discharge with a recurrence interval within the 1- to 2-year range commonly is used as a criterion for the confirmation of the bankfull stage at each streamflow-measurement station. Many researchers accept this range for recurrence interval of the bankfull discharge; however, literature provides contradictory evidence.

A Conceptual Model For Effluent-Dependent Riverine Environments

NASA Astrophysics Data System (ADS)

Murphy, M. T.; Meyerhoff, R. D.; Osterkamp, W. R.; Smith, E. L.; Hawkins, R. H.

2001-12-01

The Arid West Water Quality Research Project (WQRP) is a multi-year, EPA-funded scientific endeavor directed by the Pima County, Wastewater Management Department in southern Arizona and focussed upon several interconnected ecological questions. These questions are crucial to water quality management in the arid and semi arid western US. A key component has been the ecological, hydrological and geomorphological investigation of habitat created by the discharge of treated effluent into ephemeral streams. Such environments are fundamentally different from the dry streams or rivers they displace; however, they are clearly not the perennial streams they superficially resemble. Under Arizona State regulations, such streams can bear the use designation of "Effluent Dependent Waters," or EDWs. Before this investigation, a hydrological/ecological conceptual model for these unique ecosystems had not been published. We have constructed one for general review that is designed to direct future work in the WQRP. The project investigated ten representative, yet contrasting EDW sites distributed throughout arid areas of the western US, to gather both historical and reconnaissance level field data, including in-stream and riparian, habitat and morphometric fluvial data. In most cases, the cross sectional area of the prior channel is oversized relative to the discharge of the introduced effluent. Where bed control is absent, the channels are incised downstream of the discharge point, further suggesting a disequilibrium between the channel and the regulated effluent flow. Several of the studied stream systems primarily convey storm water and are aggradational, exhibiting braided or anastomizing channels, high energy bedforms, and spatially dynamic interfluves. Active channels are formed in response to individual storm events and can be highly dynamic in both location and cross-sectional morphology. This poses a geomorphological challenge in the selection of a discharge point. We structured the conceptual model around accepted riverine ecological models but with important departures signaling the unique characteristics of EDW communities. In many cases, in-stream habitat values were naturally limited by substrate, flow regimes, or other pre-discharge conditions. Our model is designed to give terrestrial habitat equal footing with in-stream resources in ecological assessment techniques. In the arid West, where in-stream water resources are becoming increasingly limited, EDWs offer important refugia and corridors for neotropical migratory birds and other habitat-limited wildlife species. These beneficial uses require different hydrological tools than in-stream systems for assessing habitat health.

Apparatus for diffusion separation

DOEpatents

Nierenberg, William A.; Pontius, Rex B.

1976-08-10

1. The method of testing the separation efficiency of porous permeable membranes which comprises causing a stream of a gaseous mixture to flow into contact with one face of a finely porous permeable membrane under such conditions that a major fraction of the mixture diffuses through the membrane, maintaining a rectangular cross section of the gaseous stream so flowing past said membrane, continuously recirculating the gas that diffuses through said membrane and continuously withdrawing the gas that does not diffuse through said membrane and maintaining the volume of said recirculating gas constant by continuously introducing into said continuously recirculating gas stream a mass of gas equivalent to that which is continuously withdrawn from said gas stream and comparing the concentrations of the light component in the entering gas, the withdrawn gas and the recirculated gas in order to determine the efficiency of said membrane.

Vertical Stability of Ephemeral Step-Pool Streams Largely Controlled By Tree Roots, Central Kentucky, USA

NASA Astrophysics Data System (ADS)

Macmannis, K. R.; Hawley, R. J.

2013-12-01

The mechanisms controlling stability on small streams in steep settings are not well documented but have many implications related to stream integrity and water quality. For example, channel instability on first and second order streams is a potential source of sediment in regulated areas with Total Maximum Daily Loads (TMDLs) on water bodies that are impaired for sedimentation, such as the Chesapeake Bay. Management strategies that preserve stream integrity and protect channel stability are critical to communities that may otherwise require large capital investments to meet TMDLs and other water quality criteria. To contribute to an improved understanding of ephemeral step-pool systems, we collected detailed hydrogeomorphic data on 4 steep (0.06 - 0.12 meter/meter) headwater streams draining to lower relief alluvial valleys in Spencer County, Kentucky, USA. The step-pool streams (mean step height of 0.47 meter, mean step spacing of 4 meters) drained small undeveloped catchments dominated by early successional forest. Data collection for each of the 4 streams included 2 to 3 cross section surveys, bed material particle counts at cross section locations, and profile surveys ranging from approximately 125 to 225 meters in length. All survey data was systematically processed to understand geometric parameters such as cross sectional area, depth, and top width; bed material gradations; and detailed profile measurements such as slope, pool and riffle lengths, pool spacing, pool depth, step height, and step length. We documented the location, frequency, and type of step-forming materials (i.e., large woody debris (LWD), rock, and tree roots), compiling a database of approximately 130 total steps. Lastly, we recorded a detailed tree assessment of all trees located within 2 meters of the top of bank, detailing the species of tree, trunk diameter, and approximate distance from the top of bank. Analysis of geometric parameters illustrated correlations between channel characteristics (e.g., step height was positively correlated to slope while pool spacing was inversely correlated to slope). Most importantly, we assessed the step-forming materials with respect to channel stability. LWD has been widely documented as an important component of geomorphic stability and habitat diversity across many settings; however, our research highlights the importance of roots in providing bed stability in steep, first and second-order ephemeral streams, as 40 percent of the steps in these step-pool systems were controlled by tree roots. Similar to the key member in naturally-occurring log jams, lateral tree roots frequently served as the anchor for channel steps that were often supplemented by rocks or LWD. Assessment of the trees throughout the riparian zone suggested average tree densities of 0.30 trees/square meter or 0.40 trees/meter could provide adequate riparian zone coverage to promote channel stability. These results have implications to land use planning and stormwater management. For example, on developments draining to step-pool systems, maintaining the integrity of the riparian zone would seem to be as important as ensuring hydrologic mimicry if channel integrity is to be preserved.

Evaluation of road approaches to four different types of stream crossings in the Virginia Piedmont

Treesearch

Matthew B. Carroll; W. Michael Aust; C. Andrew Dolloff; Robert M. Shaffer

2013-01-01

Erosion potential was estimated for road approaches during 4 phases of a timber harvesting scheduled for 23 stream crossings in the Virginia Piedmont. The objectives of this study were to: (1) examine four different types of stream crossing structures (steel bridges, pole bridges, standard culverts, and reenforced fords) in order to determine if the type of stream...

Morphology of a Wetland Stream

PubMed

Jurmu; Andrle

1997-11-01

/ Little attention has been paid to wetland stream morphology in the geomorphological and environmental literature, and in the recently expanding wetland reconstruction field, stream design has been based primarily on stream morphologies typical of nonwetland alluvial environments. Field investigation of a wetland reach of Roaring Brook, Stafford, Connecticut, USA, revealed several significant differences between the morphology of this stream and the typical morphology of nonwetland alluvial streams. Six morphological features of the study reach were examined: bankfull flow, meanders, pools and riffles, thalweg location, straight reaches, and cross-sectional shape. It was found that bankfull flow definitions originating from streams in nonwetland environments did not apply. Unusual features observed in the wetland reach include tight bends and a large axial wavelength to width ratio. A lengthy straight reach exists that exceeds what is typically found in nonwetland alluvial streams. The lack of convex bank point bars in the bends, a greater channel width at riffle locations, an unusual thalweg location, and small form ratios (a deep and narrow channel) were also differences identified. Further study is needed on wetland streams of various regions to determine if differences in morphology between alluvial and wetland environments can be applied in order to improve future designs of wetland channels.KEY WORDS: Stream morphology; Wetland restoration; Wetland creation; Bankfull; Pools and riffles; Meanders; Thalweg

Proceedings of the 17th biennial southern silvicultural research conference

Treesearch

A. Gordon Holley; Kristina F. Connor; James D. Haywood

2015-01-01

A range of issues affecting southern forests are addressed in 108 papers or extended abstracts. Papers are grouped in 13 sections that cover the topics of hardwood regeneration, best management practices for stream crossings, pine regeneration and genetics, fire effects, eco-physiology, forest nutrition, vegetation management, forest threats, biomass, biometrics,...

40 CFR 61.67 - Emission tests.

Code of Federal Regulations, 2010 CFR

2010-07-01

... being tested is operating at the maximum production rate at which the equipment will be operated and... cross section. The sample is to be extracted at a rate proportional to the gas velocity at the sampling... apply. The average is to be computed on a time weighted basis. (iii) For gas streams containing more...

Scaling relations in mountain streams: colluvial and Quaternary controls

NASA Astrophysics Data System (ADS)

Brardinoni, Francesco; Hassan, Marwan; Church, Michael

2010-05-01

In coastal British Columbia, Canada, the glacial palimpsest profoundly affects the geomorphic structure of mountain drainage basins. In this context, by combining remotely sensed, field- and GIS-based data, we examine the scaling behavior of bankfull width and depth with contributing area in a process-based framework. We propose a novel approach that, by detailing interactions between colluvial and fluvial processes, provides new insights on the geomorphic functioning of mountain channels. This approach evaluates the controls exerted by a parsimonious set of governing factors on channel size. Results indicate that systematic deviations from simple power-law trends in bankfull width and depth are common. Deviations are modulated by interactions between the inherited glacial and paraglacial topography (imposed slope), coarse grain-size fraction, and chiefly the rate of colluvial sediment delivery to streams. Cumulatively, departures produce distal cross-sections that are typically narrower and shallower than expected. These outcomes, while reinforcing the notion that mountain drainage basins in formerly glaciated systems are out of balance with current environmental conditions, show that cross-sectional scaling relations are useful metrics for understanding colluvial-alluvial interactions.

Mean-flow measurements of the flow field diffusing bend

NASA Technical Reports Server (NTRS)

Mcmillan, O. J.

1982-01-01

Time-average measurements of the low-speed turbulent flow in a diffusing bend are presented. The experimental geometry consists of parallel top and bottom walls and curved diverging side walls. The turning of the center line of this channel is 40 deg, the area ratio is 1.5 and the ratios of height and center-line length to throat width are 1.5 and 3, respectively. The diffusing bend is preceded and followed by straight constant area sections. The inlet boundary layers on the parallel walls are artificially thickened and occupy about 30% of the channel height; those on the side walls develop naturally and are about half as thick. The free-stream speed at the inlet was approximately 30 m/sec for all the measurements. Inlet boundary layer mean velocity and turbulence intensity profiles are presented, as are data for wall static pressures, and at six cross sections, surveys of the velocity-vector and static-pressure fields. The dominant feature of the flow field is a pair of counter-rotating streamwise vortices formed by the cross-stream pressure gradient in the bend on which an overall deceleration is superimposed.

Dye lasing arrangement including an optical assembly for altering the cross-section of its pumping beam and method

DOEpatents

O'Neil, Richard W.; Sweatt, William C.

1992-01-01

An optical assembly is disclosed herein along with a method of operation for use in a dye lasing arrangement, for example a dye laser oscillator or a dye amplifier, in which a continuous stream of dye is caused to flow through a given zone in a cooperating dye chamber while the zone is being illuminated by light from a pumping beam which is directed into the given zone. This in turn causes the dye therein to lase and thereby produce a new dye beam in the case of a dye laser oscillator or amplify a dye beam in the case of a dye amplifier. The optical assembly so disclosed is designed to alter the pump beam such that the beam enters the dye chamber with a different cross-sectional configuration, preferably one having a more uniform intensity profile, than its initially produced cross-sectional configuration. To this end, the assembly includes a network of optical components which first act on the beam while the latter retains its initially produced cross-sectional configuration for separating it into a plurality of predetermined segments and then recombines the separated components in a predetermined way which causes the recombined beam to have the different cross-sectional configuration.

FFM water mockup studies of the near-wake region of permeable flow blockages. [LMFBR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheppard, J. D.

1976-10-01

An experimental study of transport in the near-wake region of permeable, planar flow blockages was conducted in a vertical-flow channel with a hexagonal cross section. Experiments included measurements of axial pressure distributions along channel walls exposed to the free stream and wake region and pressure differences between the free stream and wake regions at fixed axial positions. Further, time constants for scalar decay in the near-wake region were determined by salt conductivity tests. A single blockage geometry was used in all tests; the blockage, which was attached to the channel wall, obstructed 58 percent of the cross section when themore » blockage was solid. For one series of tests, discrete jets were machined into the blockage and water was metered into the recirculation zone at velocities of the order of the mean channel velocity. Increased jet velocity reduced the resistence time of salt in the recirculation zone, and when the jet velocity was as high as the accelerated free stream flow at the vena contracta, counterrotating cells were introduced in the recirculating zone. In a second series of tests, uniformly spaced holes were drilled in the blockages to give blockage porosities of 11 and 24 percent. The residence time of salt in the near wake decreased significantly as the blockage porosity was increased to 24 percent.« less

Measuring flood discharge in unstable stream channels using ground-penetrating radar

USGS Publications Warehouse

Spicer, K.R.; Costa, J.E.; Placzek, G.

1997-01-01

Field experiments were conducted to test the ability of ground-penetrating radar (GPR) to measure stream-channel cross sections at high flows without the necessity of placing instruments in the water. Experiments were conducted at four U.S. Geological Survey gaging stations in southwest Washington State. With the GPR antenna suspended above the water surface from a bridge or cableway, traverses were made across stream channels to collect radar profile plots of the streambed. Subsequent measurements of water depth were made using conventional depth-measuring equipment (weight and tape) and were used to calculate radar signal velocities. Other streamflow-parameter data were collected to examine their relation to radar signal velocity and to claritv of streambed definition. These initial tests indicate that GPR is capable of producing a reasonably accurate (??20%) stream-channel profile and discharge far more quickly than conventional stream-gaging procedures, while avoiding the problems and hazards associated with placing instruments in the water.

A morphological comparison of narrow, low-gradient streams traversing wetland environments to alluvial streams.

PubMed

Jurmu, Michael C

2002-12-01

Twelve morphological features from research on alluvial streams are compared in four narrow, low-gradient wetland streams located in different geographic regions (Connecticut, Indiana, and Wisconsin, USA). All four reaches differed in morphological characteristics in five of the features compared (consistent bend width, bend cross-sectional shape, riffle width compared to pool width, greatest width directly downstream of riffles, and thalweg location), while three reaches differed in two comparisons (mean radius of curvature to width ratio and axial wavelength to width ratio). The remaining five features compared had at least one reach where different characteristics existed. This indicates the possibility of varying morphology for streams traversing wetland areas further supporting the concept that the unique qualities of wetland environments might also influence the controls on fluvial dynamics and the development of streams. If certain morphological features found in streams traversing wetland areas differ from current fluvial principles, then these varying features should be incorporated into future wetland stream design and creation projects. The results warrant further research on other streams traversing wetlands to determine if streams in these environments contain unique morphology and further investigation of the impact of low-energy fluvial processes on morphological development. Possible explanations for the morphology deviations in the study streams and some suggestions for stream design in wetland areas based upon the results and field observations are also presented.

The effects of stream crossings on total suspended sediment in North Carolina Piedmont forests

Treesearch

Johnny Boggs; Ge Sun; Steve McNulty

2017-01-01

This study determined total suspended sediment (TSS) at six stream crossings that represented a range of site conditions and forest operations in the Piedmont of North Carolina. Two wood and three steel bridgemats and one culvert were installed to cross the streams. The road classes for the crossings included four temporary skid trails and two permanent forest haul...

Tuning magnetofluidic spreading in microchannels

NASA Astrophysics Data System (ADS)

Wang, Zhaomeng; Varma, V. B.; Wang, Z. P.; Ramanujan, R. V.

2015-12-01

Magnetofluidic spreading (MFS) is a phenomenon in which a uniform magnetic field is used to induce spreading of a ferrofluid core cladded by diamagnetic fluidic streams in a three-stream channel. Applications of MFS include micromixing, cell sorting and novel microfluidic lab-on-a-chip design. However, the relative importance of the parameters which govern MFS is still unclear, leading to non-optimal control of MFS. Hence, in this work, the effect of various key parameters on MFS was experimentally and numerically studied. Our multi-physics model, which combines magnetic and fluidic analysis, showed excellent agreement between theory and experiment. It was found that spreading was mainly due to cross-sectional convection induced by magnetic forces, and can be enhanced by tuning various parameters. Smaller flow rate ratio, higher magnetic field, higher core stream or lower cladding stream dynamic viscosity, and larger magnetic particle size can increase MFS. These results can be used to tune magnetofluidic spreading in microchannels.

Flood profiles for lower Brooker Creek, west-central Florida

USGS Publications Warehouse

Murphy, W.R.

1978-01-01

Flood heights are computed for a range of recurrence intervals for a 12.6 mile reach of Brooker Creek, beginning at the mouth at Lake Tarpon. A Geological Survey step-backwater computer program, E431, was used in these analyses using: (1) Stream and valley cross-section geometry and roughness data; (2) Recurrence interval flood-peak discharges; (3) Recurrence interval starting elevations; (4) Gaging station stage-discharge relations. Flood heights may be plotted versus distance above stream mouth and connected to construct flood profiles. They may also be used to indicate areas of inundation on detailed topographic maps.

Hydrogeomorphic connectivity on roads crossing in rural headwaters and its effect on stream dynamics.

PubMed

Thomaz, Edivaldo L; Peretto, Gustavo T

2016-04-15

Unpaved roads are ubiquitous features that have been transforming the landscape through human history. Unpaved roads affect the water and sediment pathways through a catchment and impacts the aquatic ecosystem. In this study, we describe the effect of unpaved road on the hydrogeomorphic connectivity at the rural headwater scale. Measurement was based on the stream crossing approach, i.e., road superimposing the drainage system. We installed a Parshall flume coupled with single-stage suspended sediment sampler at each stream crossing. In addition, we displayed our monitoring scheme with an upscaling perspective from second-order to third-order stream. We concluded that the road-stream coupling dramatically changed the stream dynamic. The increase of discharge caused by roads at the headwater was 50% larger compared to unaffected streams. Additionally, suspended sediment concentration enhancement at stream crossings ranged from to 413% at second-order streams to 145% at third-order streams. The landform characteristics associated with the road network produced an important hydrogeomorphic disruption in the landscape. As a result, the sediment filter function of the riparian zone was reduced dramatically. Therefore, we recommend that projects for aquatic system restoration or conservation in rural landscape consider the role of the road network on stream dynamics. Copyright © 2016 Elsevier B.V. All rights reserved.

Engineering fluid flow using sequenced microstructures

NASA Astrophysics Data System (ADS)

Amini, Hamed; Sollier, Elodie; Masaeli, Mahdokht; Xie, Yu; Ganapathysubramanian, Baskar; Stone, Howard A.; di Carlo, Dino

2013-05-01

Controlling the shape of fluid streams is important across scales: from industrial processing to control of biomolecular interactions. Previous approaches to control fluid streams have focused mainly on creating chaotic flows to enhance mixing. Here we develop an approach to apply order using sequences of fluid transformations rather than enhancing chaos. We investigate the inertial flow deformations around a library of single cylindrical pillars within a microfluidic channel and assemble these net fluid transformations to engineer fluid streams. As these transformations provide a deterministic mapping of fluid elements from upstream to downstream of a pillar, we can sequentially arrange pillars to apply the associated nested maps and, therefore, create complex fluid structures without additional numerical simulation. To show the range of capabilities, we present sequences that sculpt the cross-sectional shape of a stream into complex geometries, move and split a fluid stream, perform solution exchange and achieve particle separation. A general strategy to engineer fluid streams into a broad class of defined configurations in which the complexity of the nonlinear equations of fluid motion are abstracted from the user is a first step to programming streams of any desired shape, which would be useful for biological, chemical and materials automation.

Operational forest stream crossings effects on water quality in the Virginia Piedmont

Treesearch

Wallace M. Aust; Matthew B. Carroll; M. Chad Bolding; Andy Dolloff

2011-01-01

Water quality indices were examined for paired upstream and downstream samples for 23 operational stream crossings and approaches during four periods. Stream crossings were (1) portable bridges (BRIDGE), (2) culverts backfilled with poles (POLE), (3) culverts with earth backfill (CULVERT), and (4) reinforced fords (FORD). The four operational periods were (1) prior to...

What We Know--and Don't Know--About Water Quality at Stream Crossings

Treesearch

Steven E. Taylor; Robert B. Rummer; Kyung H. Yoo; Richard A. Welch; Jason D. Thompson

1999-01-01

Forest road stream crossings including fords, culverts, and bridges, are primary contributors of sediment to forest streams. Information on the water quality impacts form each type for crossings is limited, but the available literature indicates that signicifacent amounts of sediment are produced during installation fo fords and culverts; construction and use of...

Effectiveness of best management practices for sediment reduction at operation forest stream crossings

Treesearch

Laura R. Wear; Michael W. Aust; M. Chad Bolding; Brian D. Strahm; C. Andrew Dolloff

2013-01-01

Temporary skid trail stream crossings have repeatedly been identified as having considerable potential to introduce sediment to streams. Forestry Best Management Practices (BMPs) have proven to be effective for controlling erosion and subsequent sedimentation, yet few studies have quantified sedimentation associated with various levels of BMPs for skidder stream...

Definition and fabrication of an airborne scatterometer radar signal processor

NASA Technical Reports Server (NTRS)

1976-01-01

A hardware/software system which incorporates a microprocessor design and software for the calculation of normalized radar cross section in real time was developed. Interface is provided to decommutate the NASA ADAS data stream for aircraft parameters used in processing and to provide output in the form of strip chart and pcm compatible data recording.

Accounting for multiple stressors in regional stream ecosystem analysis: A demonstration with riparian invasive plants

EPA Science Inventory

Background/Questions/Methods: Large cross-sectional data sets allow testing of hypotheses about how one part of an ecosystem relates to other parts. Tests such as these are of interest for many reasons, one of which is to gain insight into the role of stressors, such as land co...

A New Streamflow-Routing (SFR1) Package to Simulate Stream-Aquifer Interaction with MODFLOW-2000

USGS Publications Warehouse

Prudic, David E.; Konikow, Leonard F.; Banta, Edward R.

2004-01-01

The increasing concern for water and its quality require improved methods to evaluate the interaction between streams and aquifers and the strong influence that streams can have on the flow and transport of contaminants through many aquifers. For this reason, a new Streamflow-Routing (SFR1) Package was written for use with the U.S. Geological Survey's MODFLOW-2000 ground-water flow model. The SFR1 Package is linked to the Lake (LAK3) Package, and both have been integrated with the Ground-Water Transport (GWT) Process of MODFLOW-2000 (MODFLOW-GWT). SFR1 replaces the previous Stream (STR1) Package, with the most important difference being that stream depth is computed at the midpoint of each reach instead of at the beginning of each reach, as was done in the original Stream Package. This approach allows for the addition and subtraction of water from runoff, precipitation, and evapotranspiration within each reach. Because the SFR1 Package computes stream depth differently than that for the original package, a different name was used to distinguish it from the original Stream (STR1) Package. The SFR1 Package has five options for simulating stream depth and four options for computing diversions from a stream. The options for computing stream depth are: a specified value; Manning's equation (using a wide rectangular channel or an eight-point cross section); a power equation; or a table of values that relate flow to depth and width. Each stream segment can have a different option. Outflow from lakes can be computed using the same options. Because the wetted perimeter is computed for the eight-point cross section and width is computed for the power equation and table of values, the streambed conductance term no longer needs to be calculated externally whenever the area of streambed changes as a function of flow. The concentration of solute is computed in a stream network when MODFLOW-GWT is used in conjunction with the SFR1 Package. The concentration of a solute in a stream reach is based on a mass-balance approach and accounts for exchanges with (inputs from or losses to) ground-water systems. Two test examples are used to illustrate some of the capabilities of the SFR1 Package. The first test simulation was designed to illustrate how pumping of ground water from an aquifer connected to streams can affect streamflow, depth, width, and streambed conductance using the different options. The second test simulation was designed to illustrate solute transport through interconnected lakes, streams, and aquifers. Because of the need to examine time series results from the model simulations, the Gage Package first described in the LAK3 documentation was revised to include time series results of selected variables (streamflows, stream depth and width, streambed conductance, solute concentrations, and solute loads) for specified stream reaches. The mass-balance or continuity approach for routing flow and solutes through a stream network may not be applicable for all interactions between streams and aquifers. The SFR1 Package is best suited for modeling long-term changes (months to hundreds of years) in ground-water flow and solute concentrations using averaged flows in streams. The Package is not recommended for modeling the transient exchange of water between streams and aquifers when the objective is to examine short-term (minutes to days) effects caused by rapidly changing streamflows.

Mapping Spatial Distributions of Stream Power and Channel Change along a Gravel-Bed River in Northern Yellowstone

NASA Astrophysics Data System (ADS)

Lea, D. M.; Legleiter, C. J.

2014-12-01

Stream power represents the rate of energy expenditure along a river and can be calculated using topographic data acquired via remote sensing. This study used remotely sensed data and field measurements to quantitatively relate temporal changes in the form of Soda Butte Creek, a gravel-bed river in northeastern Yellowstone National Park, to stream power gradients along an 8 km reach. Aerial photographs from 1994-2012 and cross-section surveys were used to assess lateral channel mobility and develop a morphologic sediment budget for quantifying net sediment flux for a series of budget cells. A drainage area-to-discharge relationship and digital elevation model (DEM) developed from LiDAR data were used to obtain the discharge and slope values, respectively, needed to calculate stream power. Local and lagged relationships between mean stream power gradient at median peak discharge and volumes of erosion, deposition, and net sediment flux were quantified via spatial cross-correlation analyses. Similarly, autocorrelations of locational probabilities and sediment fluxes were used to examine spatial patterns of channel mobility and sediment transfer. Energy expended above critical stream power was calculated for each time period to relate the magnitude and duration of peak flows to the total volume of sediment eroded or deposited during each time increment. Our results indicated a lack of strong correlation between stream power gradients and sediment flux, which we attributed to the geomorphic complexity of the Soda Butte Creek watershed and the inability of our relatively simple statistical approach to link sediment dynamics expressed at a sub-budget cell scale to larger-scale driving forces such as stream power gradients. Future studies should compare the moderate spatial resolution techniques used in this study to very-high resolution data acquired from new fluvial remote sensing technologies to better understand the amount of error associated with stream power, sediment transport, and channel change calculated from historical datasets.

Mapping spatial patterns of stream power and channel change along a gravel-bed river in northern Yellowstone

NASA Astrophysics Data System (ADS)

Lea, Devin M.

Stream power represents the rate of energy expenditure along a river and can be calculated using topographic data acquired via remote sensing or field surveys. This study used remote sensing and GIS tools along with field data to quantitatively relate temporal changes in the form of Soda Butte Creek, a gravel-bed river in northeastern Yellowstone National Park, to stream power gradients along an 8 km reach. Aerial photographs from 1994-2012 and cross-section surveys were used to develop a locational probability map and morphologic sediment budget to assess lateral channel mobility and changes in net sediment flux. A drainage area-to-discharge relationship and digital elevation model (DEM) developed from light detection and ranging (LiDAR) data were used to obtain the discharge and slope values needed to calculate stream power. Local and lagged relationships between mean stream power gradient at median peak discharge and volumes of erosion, deposition, and net sediment flux were quantified via spatial cross-correlation analyses. Similarly, autocorrelations of locational probabilities and sediment fluxes were used to examine spatial patterns of sediment sources and sinks. Energy expended above critical stream power was calculated for each time period to relate the magnitude and duration of peak flows to the total volumetric change in each time increment. Results indicated a lack of strong correlation between stream power gradients and sediment response, highlighting the geomorphic complexity of Soda Butte Creek and the inability of relatively simple statistical approaches to link sub-budget cell-scale sediment dynamics to larger-scale driving forces such as stream power gradients. Improving the moderate spatial resolution techniques used in this study and acquiring very-high resolution data from recently developed methods in fluvial remote sensing could help improve understanding of the spatial organization of stream power, sediment transport, and channel change in dynamic natural rivers.

Large-scale structure perturbation theory without losing stream crossing

NASA Astrophysics Data System (ADS)

McDonald, Patrick; Vlah, Zvonimir

2018-01-01

We suggest an approach to perturbative calculations of large-scale clustering in the Universe that includes from the start the stream crossing (multiple velocities for mass elements at a single position) that is lost in traditional calculations. Starting from a functional integral over displacement, the perturbative series expansion is in deviations from (truncated) Zel'dovich evolution, with terms that can be computed exactly even for stream-crossed displacements. We evaluate the one-loop formulas for displacement and density power spectra numerically in 1D, finding dramatic improvement in agreement with N-body simulations compared to the Zel'dovich power spectrum (which is exact in 1D up to stream crossing). Beyond 1D, our approach could represent an improvement over previous expansions even aside from the inclusion of stream crossing, but we have not investigated this numerically. In the process we show how to achieve effective-theory-like regulation of small-scale fluctuations without free parameters.

Presenting the master of all conductivity meters, and how it tastes streamflow

NASA Astrophysics Data System (ADS)

Weijs, S. V.; Parlange, M. B.

2012-04-01

For measuring streamflow in small Alpine streams, the salt dilution method is suitable and often used. By injecting a known mass of salt in the stream and measuring the downstream salt concentration as a function of time, we can obtain the streamflow by integration of the time signal. The underlying assumption is that the salt is well mixed within the stream cross-section. In this method, the salt concentration us usually measured through its relation with conductivity. Several commercial systems exist to do these conductivity measurements and automatically process the results. The problem we encountered when using these systems, however, is that uncertainty is often hidden under the hood. Because the processing happens onboard, researchers may be tempted to put too much trust in the final measurement outcomes. This is somewhat remediated by using a system with two probes which are individually processed to a streamflow outcome. We found that the salt-wave was differently shaped for the faster part of the stream compared to the sides, and therefore gave different readings for the discharge. To come a more probabilistic characterization of streamflow, and to know what is under the hood, we decided to build our own conductivity meter, equipped with eight probes covering the cross section. This enables quantifying some of the uncertainty in the streamflow measurements, which is important for testing hydrological models. This poster shows the first results and the hardware setup. We based our hardware on the open source hardware platform Arduino, and believe that by sharing both the design and the drawbacks, we contribute to the evolution of better measurement equipment or at least better understanding of its shortcomings.

Recreational Stream Crossing Effects on Sediment Delivery and Macroinvertebrates in Southwestern Virginia, USA

NASA Astrophysics Data System (ADS)

Kidd, Kathryn R.; Aust, W. Michael; Copenheaver, Carolyn A.

2014-09-01

Trail-based recreation has increased over recent decades, raising the environmental management issue of soil erosion that originates from unsurfaced, recreational trail systems. Trail-based soil erosion that occurs near stream crossings represents a non-point source of pollution to streams. We modeled soil erosion rates along multiple-use (hiking, mountain biking, and horseback riding) recreational trails that approach culvert and ford stream crossings as potential sources of sediment input and evaluated whether recreational stream crossings were impacting water quality based on downstream changes in macroinvertebrate-based indices within the Poverty Creek Trail System of the George Washington and Jefferson National Forest in southwestern Virginia, USA. We found modeled soil erosion rates for non-motorized recreational approaches that were lower than published estimates for an off-road vehicle approach, bare horse trails, and bare forest operational skid trail and road approaches, but were 13 times greater than estimated rates for undisturbed forests and 2.4 times greater than a 2-year old clearcut in this region. Estimated soil erosion rates were similar to rates for skid trails and horse trails where best management practices (BMPs) had been implemented. Downstream changes in macroinvertebrate-based indices indicated water quality was lower downstream from crossings than in upstream reference reaches. Our modeled soil erosion rates illustrate recreational stream crossing approaches have the potential to deliver sediment into adjacent streams, particularly where BMPs are not being implemented or where approaches are not properly managed, and as a result can negatively impact water quality below stream crossings.

Generalized additive regression models of discharge and mean velocity associated with direct-runoff conditions in Texas: Utility of the U.S. Geological Survey discharge measurement database

USGS Publications Warehouse

Asquith, William H.; Herrmann, George R.; Cleveland, Theodore G.

2013-01-01

A database containing more than 17,700 discharge values and ancillary hydraulic properties was assembled from summaries of discharge measurement records for 424 U.S. Geological Survey streamflow-gauging stations (stream gauges) in Texas. Each discharge exceeds the 90th-percentile daily mean streamflow as determined by period-of-record, stream-gauge-specific, flow-duration curves. Each discharge therefore is assumed to represent discharge measurement made during direct-runoff conditions. The hydraulic properties of each discharge measurement included concomitant cross-sectional flow area, water-surface top width, and reported mean velocity. Systematic and statewide investigation of these data in pursuit of regional models for the estimation of discharge and mean velocity has not been previously attempted. Generalized additive regression modeling is used to develop readily implemented procedures by end-users for estimation of discharge and mean velocity from select predictor variables at ungauged stream locations. The discharge model uses predictor variables of cross-sectional flow area, top width, stream location, mean annual precipitation, and a generalized terrain and climate index (OmegaEM) derived for a previous flood-frequency regionalization study. The mean velocity model uses predictor variables of discharge, top width, stream location, mean annual precipitation, and OmegaEM. The discharge model has an adjusted R-squared value of about 0.95 and a residual standard error (RSE) of about 0.22 base-10 logarithm (cubic meters per second); the mean velocity model has an adjusted R-squared value of about 0.67 and an RSE of about 0.063 fifth root (meters per second). Example applications and computations using both regression models are provided. - See more at: http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29HE.1943-5584.0000635#sthash.jhGyPxgZ.dpuf

Fluvial sediments a summary of source, transportation, deposition, and measurement of sediment discharge

USGS Publications Warehouse

Colby, B.R.

1963-01-01

This paper presents a broad but undetailed picture of fluvial sediments in streams, reservoirs, and lakes and includes a discussion of the processes involved in the movement of sediment by flowing water. Sediment is fragmental material that originates from the chemical or physical disintegration of rocks. The disintegration products may have many different shapes and may range in size from large boulders to colloidal particles. In general, they retain about the same mineral composition as the parent rocks. Rock fragments become fluvial sediment when they are entrained in a stream of water. The entrainment may occur as sheet erosion from land surfaces, particularly for the fine particles, or as channel erosion after the surface runoff has accumulated in streams. Fluvial sediments move in streams as bedload (particles moving within a few particle diameters of the streambed) or as suspended sediment in the turbulent flow. The discharge of bedload varies with several factors, which may include particle size and a type of effective shear on the surface of the streambed. The discharge of suspended sediment depends partly on concentration of moving sediment near the streambed and hence on discharge of bedload. However, the concentration of fine sediment near the streambed varies widely, even for equal flows, and, therefore, the discharge of fine sediment normally cannot be computed theoretically. The discharge of suspended sediment also depends on velocity, turbulence, depth of flow, and fall velocity of the particles. In general, the coarse sediment transported by a stream moves intermittently and is discharged at a rate that depends on properties of the flow and of the sediment. If an ample supply of coarse sediment is available at the surface of the streambed, the discharge of the coarse sediment, such as sand, can be roughly computed from properties of the available sediment and of the flow. On the other hand, much of the fine sediment in a stream usually moves nearly continuously at about the velocity of the flow, and even low flows can transport large amounts of fine sediment. Hence, the discharge of fine sediments, being largely dependent on the availability of fine sediment upstream rather than on the properties of the sediment and of the flow at a cross section, can seldom be computed from properties, other than concentrations based directly on samples, that can be observed at the cross section. Sediment particles continually change their positions in the flow; some fall to the streambed, and others are removed from the bed. Sediment deposits form locally or over large areas if the volume rate at which particles settle to the bed exceeds the volume rate at which particles are removed from the bed. In general, large particles are deposited more readily than small particles, whether the point of deposition is behind a rock, on a flood plain, within a stream channel, or at the entrance to a reservoir, a lake, or the ocean. Most samplers used for sediment observations collect a water-sediment mixture from the water surface to within a few tenths of a foot of the streambed. They thus sample most of the suspended sediment, especially if the flow is deep or if the sediment is mostly fine; but they exclude the bedload and some of the suspended sediment in a layer near the streambed where the suspended-sediment concentrations are highest. Measured sediment discharges are usually based on concentrations that are averages of several individual sediment samples for a cross section. If enough average concentrations for a cross section have been determined, the measured sediment discharge can be computed by interpolating sediment concentrations between sampling times. If only occasional samples were collected, an average relation between sediment discharge and flow can be used with a flow-duration curve to compute roughly the average or the total sediment discharges for any periods of time for which the flow-duration c

Temporary stream and wetland crossing options for forest management.

Treesearch

Charles R. Blinn; Rick Dahlman; Lola Hislop; Michael A. Thompson

1998-01-01

Discusses temporary options for crossing streams and wetland soils with forest harvesting and transportation equipment. Reviews the available literature on the environmental effects of temporary crossings. Provides an overview of regulations pertaining to temporary crossings for several jurisdictions in the Great Lakes Region.

Temporary stream and wetland crossing options for forest management

Treesearch

Charles R. Blinn; Rick Dahlman; Lola Hislop; Michael A. Thompson

1998-01-01

Discusses temporary options for crossing streams and wetland soils with forest harvesting and transportation equipment. Reviews the available literature on the environmental effects of temporary crossings. Provides an overview of regulations pertaining to temporary crossings for several jurisdictions in the Great Lakes Region.

Hydrodynamics and sediment transport in a meandering channel with a model axial-flow hydrokinetic turbine

NASA Astrophysics Data System (ADS)

Hill, Craig; Kozarek, Jessica; Sotiropoulos, Fotis; Guala, Michele

2016-02-01

An investigation into the interactions between a model axial-flow hydrokinetic turbine (rotor diameter, dT = 0.15 m) and the complex hydrodynamics and sediment transport processes within a meandering channel was carried out in the Outdoor StreamLab research facility at the University of Minnesota St. Anthony Falls Laboratory. This field-scale meandering stream with bulk flow and sediment discharge control provided a location for high spatiotemporally resolved measurements of bed and water surface elevations around the model turbine. The device was installed within an asymmetric, erodible channel cross section under migrating bed form and fixed outer bank conditions. A comparative analysis between velocity and topographic measurements, with and without the turbine installed, highlights the local and nonlocal features of the turbine-induced scour and deposition patterns. In particular, it shows how the cross-section geometry changes, how the bed form characteristics are altered, and how the mean flow field is distorted both upstream and downstream of the turbine. We further compare and discuss how current energy conversion deployments in meander regions would result in different interactions between the turbine operation and the local and nonlocal bathymetry compared to straight channels.

Results From a Channel Restoration Project: Hydraulic Design Considerations

USGS Publications Warehouse

Karle, K.F.; Densmore, R.V.; ,

2001-01-01

Techniques for the hydraulic restoration of placer-mined streams and floodplains were developed in Denali National Park and Preserve, Alaska. The two-year study at Glen Creek focused on a design of stream and floodplain geometry using hydraulic capacity and shear stress equations. Slope and sinuosity values were based on regional relationships. Design requirements included a channel capacity for a bankfull discharge and a floodplain capacity for a 1.5- to 100-year discharge. Several bio-engineering techniques using alder and willow, including anchored brush bars, streambank hedge layering, seedlings, and cuttings, were tested to dissipate floodwater energy and encourage sediment deposition until natural revegetation stabilized the new floodplains. Permanently monumented cross-sections installed throughout the project site were surveyed every one to three years. Nine years after the project began, a summer flood caused substantial damage to the channel form, including a change in width/depth ratio, slope, and thalweg location. Many of the alder brush bars were heavily damaged or destroyed, resulting in significant bank erosion. This paper reviews the original hydraulic design process, and describes changes to the channel and floodplain geometry over time, based on nine years of cross-section surveys.

Stream channel cross sections for a reach of the Boise River in Ada County, Idaho

USGS Publications Warehouse

Hortness, Jon E.; Werner, Douglas C.

1999-01-01

The Federal Emergency Management Agency produces maps of areas that are likely to be inundated during major floods, usually the 100-year, or 1-percent probability, flood. The maps, called Flood Insurance Rate Maps, are used to determine flood insurance rates for homes, businesses, or other structures located in flood-prone areas. State and local governments also use these maps for help with, among other things, development planning and disaster mitigation. During the period October 1997 through December 1998, the initial phase of a hydraulic analysis project of the Boise River from Barber Dam to the Ada/Canyon County boundary, the U.S. Geological Survey collected stream channel cross-section data at 238 locations along the river and documented 108 elevation reference marks established for horizontal and vertical control. In the final phase of the project, the Survey will use these data to determine water-surface elevations for the 10-, 50-, 100-, and 500-year floods and to define floodway limits. The Federal Emergency Management Agency will use the results of this hydraulic analysis to update the 100- and 500-year flood boundaries and the floodway limits on their Flood Insurance Rate Maps.

Large-scale structure perturbation theory without losing stream crossing

DOE PAGES

McDonald, Patrick; Vlah, Zvonimir

2018-01-10

Here, we suggest an approach to perturbative calculations of large-scale clustering in the Universe that includes from the start the stream crossing (multiple velocities for mass elements at a single position) that is lost in traditional calculations. Starting from a functional integral over displacement, the perturbative series expansion is in deviations from (truncated) Zel’dovich evolution, with terms that can be computed exactly even for stream-crossed displacements. We evaluate the one-loop formulas for displacement and density power spectra numerically in 1D, finding dramatic improvement in agreement with N-body simulations compared to the Zel’dovich power spectrum (which is exact in 1D upmore » to stream crossing). Beyond 1D, our approach could represent an improvement over previous expansions even aside from the inclusion of stream crossing, but we have not investigated this numerically. In the process we show how to achieve effective-theory-like regulation of small-scale fluctuations without free parameters.« less

Large-scale structure perturbation theory without losing stream crossing

DOE Office of Scientific and Technical Information (OSTI.GOV)

McDonald, Patrick; Vlah, Zvonimir

Here, we suggest an approach to perturbative calculations of large-scale clustering in the Universe that includes from the start the stream crossing (multiple velocities for mass elements at a single position) that is lost in traditional calculations. Starting from a functional integral over displacement, the perturbative series expansion is in deviations from (truncated) Zel’dovich evolution, with terms that can be computed exactly even for stream-crossed displacements. We evaluate the one-loop formulas for displacement and density power spectra numerically in 1D, finding dramatic improvement in agreement with N-body simulations compared to the Zel’dovich power spectrum (which is exact in 1D upmore » to stream crossing). Beyond 1D, our approach could represent an improvement over previous expansions even aside from the inclusion of stream crossing, but we have not investigated this numerically. In the process we show how to achieve effective-theory-like regulation of small-scale fluctuations without free parameters.« less

Stream channel responses and soil loss at off-highway vehicle stream crossings in the Ouachita National Forest

Treesearch

Daniel A. Marion; Jonathan D. Phillips; Chad Yocum; Stephanie H. Mehlhope

2014-01-01

This study investigates the geomorphic effects of ford-type stream crossings in an off-highway vehicle (OHV) trail complex in the Ouachita National Forest, Arkansas. At a total of 15 crossing sites, we used a disturbed vs. undisturbed study design to assess soil truncation and an upstream vs. downstream design to assess in-channel effects. The 15 sites ranged from OHV...

Physical integrity: the missing link in biological monitoring and TMDLs.

PubMed

Asmus, Brenda; Magner, Joseph A; Vondracek, Bruce; Perry, Jim

2009-12-01

The Clean Water Act mandates that the chemical, physical, and biological integrity of our nation's waters be maintained and restored. Physical integrity has often been defined as physical habitat integrity, and as such, data collected during biological monitoring programs focus primarily on habitat quality. However, we argue that channel stability is a more appropriate measure of physical integrity and that channel stability is a foundational element of physical habitat integrity in low-gradient alluvial streams. We highlight assessment tools that could supplement stream assessments and the Total Maximum Daily Load stressor identification process: field surveys of bankfull cross-sections; longitudinal thalweg profiles; particle size distribution; and regionally calibrated, visual, stream stability assessments. Benefits of measuring channel stability include a more informed selection of reference or best attainable stream condition for an Index of Biotic Integrity, establishment of a baseline for monitoring changes in present and future condition, and indication of channel stability for investigations of chemical and biological impairments associated with sediment discontinuity and loss of habitat quality.

Broadening of Analyte Streams due to a Transverse Pressure Gradient in Free-Flow Isoelectric Focusing

PubMed Central

Dutta, Debashis

2017-01-01

Pressure-driven cross-flows can arise in free-flow isoelectric focusing systems (FFIEF) due to a non-uniform electroosmotic flow velocity along the channel width induced by the pH gradient in this direction. In addition, variations in the channel cross-section as well as unwanted differences in hydrostatic heads at the buffer/sample inlet ports can also lead to such pressure-gradients which besides altering the equilibrium position of the sample zones have a tendency to substantially broaden their widths deteriorating the separations. In this situation, a thorough assessment of stream broadening due to transverse pressure-gradients in FFIEF devices is necessary in order to establish accurate design rules for the assay. The present article describes a mathematical framework to estimate the noted zone dispersion in FFIEF separations based on the method-of-moments approach under laminar flow conditions. A closed-form expression has been derived for the spatial variance of the analyte streams at their equilibrium positions as a function of the various operating parameters governing the assay performance. This expression predicts the normalized stream variance under the chosen conditions to be determined by two dimensionless Péclet numbers evaluated based on the transverse pressure-driven and electrophoretic solute velocities in the separation chamber, respectively. Moreover, the analysis shows that while the stream width can be expected to increase with an increase in the value of the first Péclet number, the opposite trend will be followed with respect to the latter. The noted results have been validated using Monte Carlo simulations that also establish a time/length scale over which the predicted equilibrium stream width is attained in the system. PMID:28081900

Micro-environment measurement along a climatic gradient

NASA Astrophysics Data System (ADS)

Szita, Renáta; Ambrus, András

2017-04-01

Aquatic macroinvertebrates are heavily influenced by the climatic changes even in temperate, forested habitats. The potential impacts of global climate change may be an increase in water temperatures, changes in seasonal patterns (including intensity) of precipitation and runoff which can alter hydrologic characteristics of aquatic systems. Rapid changes in hydrology caused by extreme heavy rainfalls - especially if there are clearcuts within the catchment area - may cause changes in the hydromorphology, restructure the stream bed or alter the path of the stream itself. All these affect the species composition, that is why the investigated aquatic ecosystems, the streams in forested area have limited ability to adapt to climate change. In recent study, the samples were taken from three streams which are located in similar, forested areas. The sampling sites were chosen along a climatic gradient. The first sampling site is in Mecsek mountains (South Hungary), the second one is in Kőszeg mountains (West Hungary) and the third one is in Sopron mountains (Northwest Hungary). The biological samples were taken with a specific cross-section transect arrangement, applying a new, microhabitat-based quadrat sampling method in all selected areas. Parallel with the macroinvertebrate sampling, there were taken hydraulic measures too. The velocity profile, shear velocity, shear stress, drag force and the Reynold's and Froude numbers were estimated to define the near-bed hydraulic conditions, which influence the community structure of aquatic macroinvertebrates. The main aims of the study were recognize differences along the climatic gradient in a similar habitat types of small streams in forested area if there are any, check up the ability of detection fine differences between similar communities of the new sampling methode which focuses on the microhabitat-structure of certain stream sections instead of taking and analyzing composit samples from the whole section. One more additional important aim was to investigate the microhabitat preference of the Habitats Directive Annex II. Dragonfly species, the Cordulegaster heros which inhabits each sampling sites. This project was partly supported by VKSZ_12-1-2013-0034 project.

UV Polymerization of Hydrodynamically Shaped Fibers

DTIC Science & Technology

2011-01-01

using passive wall structures was used to shape a prepolymer stream, which was subsequently polymerized using UV exposure. The shape designed using flow...simulations was maintained, and the size of the fibers was controlled using the ratio of the flow rates of the sheath and the prepolymer . The fibers... prepolymer fluids. This microfluidic approach for production of fibers with defined cross-sectional shape can produce fibers for further development

Recommendations for constructing forest stream crossings to control soil losses

Treesearch

Pamela J. Edwards; Jingxin Wang; Joshua T. Stedman

2009-01-01

Stream water samples were collected once daily and throughout storms from a small forested watershed in north central West Virginia for approximately 8 years. The turbidities of the samples were measured to determine how water quality changed in response to the construction of three associated stream crossings. The influence of the...

17. WAIKOLU STREAM CROSSING NO. 2, CONSTRUCTED 19371938, AT THE ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

17. WAIKOLU STREAM CROSSING NO. 2, CONSTRUCTED 1937-1938, AT THE MOUTH OF WAIKOLU STREAM ON THE BEACH (80' ALTITUDE). VIEW UPSTREAM INTO WAIKOLU VALLEY. NOTE RAIN-PRODUCING CLOUD COVER GATHERED AT THE HEAD OF THE VALLEY. - Kalaupapa Water Supply System, Waikolu Valley to Kalaupapa Settlement, Island of Molokai, Kalaupapa, Kalawao County, HI

Transverse liquid fuel jet breakup, burning, and ignition. M.S. Thesis

NASA Technical Reports Server (NTRS)

Li, Hsi-Shang

1990-01-01

An analytical study of the breakup, burning, and ignition of liquid fuels injected transversely into a hot air stream is conducted. The non-reacting liquid jet breakup location is determined by the local sonic point criterion. Two models, one employing analysis of an elliptical jet cross-section and the other employing a two-dimensional blunt body to represent the transverse jet, were used for sonic point calculations. An auxiliary criterion based on surface tension stability is used as a separate means of determining the breakup location. For the reacting liquid jet problem, a diffusion flame supported by a one-step chemical reaction within the gaseous boundary layer is solved along the ellipse surface in subsonic cross flow. Typical flame structures and concentration profiles were calculated for various locations along the jet cross-section as a function of upstream Mach numbers. The integration reaction rate along the jet cross-section is used to predict ignition position, which is found to be situated near the stagnation point. While a multi-step reaction is needed to represent the ignition process more accurately, the present calculation does yield reasonable predictions concerning ignition along a curved surface.

Hot SPOT Eclipses in Dwarf Novae

NASA Astrophysics Data System (ADS)

Smak, J.

1996-10-01

Eclipses of the hot spot in four dwarf novae: U Gem, IP Peg, Z Cha, and OY Car are re-analyzed, assuming two models for the shape of the spot. In Model 1 an elliptical spot is assumed, with the semi-axes s_a in the orbital plane and s_b perpendicular to the orbital plane, its center located on the stream trajectory. The results show that such an ellipse is, within errors, tangent to the disk's circumference. In all four cases the resulting dimensions of the spot s_a are larger than the theoretical cross-section of the stream. Accordingly, in Model2 the spot is assumed to consist of a head, centered on the stream trajectory, and a tail, extending downstream, ie., along disk's circumference. In some cases the resulting parameters, eg., mass ratios or disk radii, differ significantly from those obtained with Model 1.

A study of density measurements in hypersonic helium tunnels using an electron beam fluorescence technique

NASA Technical Reports Server (NTRS)

Honaker, W. C.; Hunter, W. W., Jr.; Woods, W. C.

1979-01-01

A series of experiments have been conducted at Langley Research Center to determine the feasibility of using electron-beam fluorescence to measure the free-stream static density of gaseous helium flow over a wide range of conditions. These experiments were conducted in the Langley hypersonic helium tunnel facility and its 3-inch prototype. Measurements were made for a range of stagnation pressures and temperatures and produced free-stream number densities of 1.53 x 10 to the 23rd to 1.25 x 10 to the 24th molecules/cu m and static temperatures from 2 K to 80 K. The results showed the collision quenching cross section to be 4.4 x 10 to the -15th sq cm at 1 K and to have a weak temperature dependence of T to the 1/6. With knowledge of these two values, the free-stream number density can be measured quite accurately.

Hydrology, geomorphology, and flood profiles of Lemon Creek, Juneau, Alaska

USGS Publications Warehouse

Host, Randy H.; Neal, Edward G.

2005-01-01

Lemon Creek near Juneau, Alaska has a history of extensive gravel mining, which straightened and deepened the stream channel in the lower reaches of the study area. Gravel mining and channel excavation began in the 1940s and continued through the mid-1980s. Time sequential aerial photos and field investigations indicate that the channel morphology is reverting to pre-disturbance conditions through aggradation of sediment and re-establishment of braided channels, which may result in decreased channel conveyance and increased flooding potential. Time sequential surveys of selected channel cross sections were conducted in an attempt to determine rates of channel aggradation/degradation throughout three reaches of the study area. In order to assess flooding potential in the lower reaches of the study area the U.S. Army Corps of Engineers Hydrologic Engineering Center River Analysis System model was used to estimate the water-surface elevations for the 2-, 10-, 25-, 50-, and 100-year floods. A regionally based regression equation was used to estimate the magnitude of floods for the selected recurrence intervals. Forty-two cross sections were surveyed to define the hydraulic characteristics along a 1.7-mile reach of the stream. High-water marks from a peak flow of 1,820 cubic feet per second, or about a 5-year flood, were surveyed and used to calibrate the model throughout the study area. The stream channel at a bridge in the lower reach could not be simulated without violating assumptions of the model. A model without the lower bridge indicates flood potential is limited to a small area.

Final Section of Australia's Moomba-Sydney line completed

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ives, G. Jr.

1976-12-01

Newham-Techint Gas Line JV, a joint venture between Techint Engineering (Australia) Inc. and Eric Newham (Wallerawang) Pty. Ltd., has finished construction of the final 58-mile leg of the Moomba-Sydney gas line. More than half the line is owned by The Pipeline Authority (a goverment department); the remainder belongs to the privately owned Australian Gas Light Co. Along the right-of-way, the terrain varies from an open farm belt to some 28 miles of rugged sandstone requiring blasting and drilling. In addition, the excessive number of river (2) and stream (43) crossings presented considerable problems to work crews. At the river-crossing sections,more » the pipe was installed (with a minimum of 3-ft cover) in the dry after crews temporarily dammed the river.« less

Hydraulic characteristics of the New River in the New River Gorge National River, West Virginia

USGS Publications Warehouse

Wiley, J.B.; Appel, David H.

1989-01-01

Traveltime, dispersion, water-surface and streambed profiles, and cross-section data were collected for use in application of flow and solute-transport models to the New River in the New River Gorge National River, West Virginia. Dye clouds subjected to increasing and decreasing flow rates (unsteady flow) showed that increasing flows shorten the cloud and decreasing flows lengthen the cloud. After the flow rate was changed and the flow was again steady, traveltime and dispersion characteristics were determined by the new rate of flow. Seven stage/streamflow relations identified the general changes of stream geometry throughout the study reach. Channel cross sections were estimated for model input. Low water and streambed profiles were developed from surveyed water surface elevations and water depths. (USGS)

Stream-crossing structure for deer fence

Treesearch

Robert M. Blair; James A. Hays; Louis Brunett

1963-01-01

Stream crossings are the most vulnerable points in a deer-proof fence. When an inadequately constructed crossing washes out, enclosed deer may escape and unwanted animals enter. Structures of the type described here have withstood 2 years of frequent, severe flooding in the pine-hardwood hills of central Louisiana.

An analytical solution for Dean flow in curved ducts with rectangular cross section

NASA Astrophysics Data System (ADS)

Norouzi, M.; Biglari, N.

2013-05-01

In this paper, a full analytical solution for incompressible flow inside the curved ducts with rectangular cross-section is presented for the first time. The perturbation method is applied to solve the governing equations and curvature ratio is considered as the perturbation parameter. The previous perturbation solutions are usually restricted to the flow in curved circular or annular pipes related to the overly complex form of solutions or singularity situation for flow in curved ducts with non-circular shapes of cross section. This issue specifies the importance of analytical studies in the field of Dean flow inside the non-circular ducts. In this study, the main flow velocity, stream function of lateral velocities (secondary flows), and flow resistance ratio in rectangular curved ducts are obtained analytically. The effect of duct curvature and aspect ratio on flow field is investigated as well. Moreover, it is important to mention that the current analytical solution is able to simulate the Taylor-Görtler and Dean vortices (vortices in stable and unstable situations) in curved channels.

Water quality effects of herded stream crossings by domestic sheep bands.

PubMed

Clark, Patrick E; Moffet, Corey A; Lewis, Gregory S; Seyfried, Mark S; Hardegree, Stuart P; Pierson, Fredrick B

2012-01-01

Livestock impacts on total suspended solids (TSS) and pathogen (e.g., ) levels in rangeland streams are a serious concern worldwide. Herded stream crossings by domestic sheep () are periodic, necessary managerial events on high-elevation rangelands, but their impacts on stream water quality are largely unknown. We evaluated the effects of herded, one-way crossings by sheep bands (about 2000 individuals) on TSS and concentration and load responses in downstream waters. Crossing trials were conducted during the summers of 2005 and 2006 on two reaches within each of three perennial streams in the Centennial Mountains of eastern Idaho and southwestern Montana. Water samples were collected at 2-min intervals at an upstream background station and at stations 25, 100, 500, and 1500 m downstream just before and during each crossing trial. Crossings produced substantial increases in TSS and concentrations and loads downstream, but these concentration increases were localized and short lived. Maximum TSS concentration was highest 25 m downstream, declined as a function of downstream distance, and at 500 m downstream was similar to background. Post-peak TSS concentrations at all downstream stations decreased to <25 mg L within 24 to 48 min after reaching their maxima. Findings for concentration and load responses were similar to that of TSS but less clear cut. Stream-crossing sheep do affect water quality; therefore, producers and resource managers should continue to evaluate the efficacy of herdsmanship techniques for reducing water quality impact. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Influence of a Large Free Stream Disturbance Level on Dynamics of a Jet in a Cross Flow

NASA Technical Reports Server (NTRS)

Foss, J. J.; Wark, C. E.

1983-01-01

An experiment to study the physical agents that are responsible for the jet turning into the streamwise direction, and the mixing of the jet and the cross stream fluid in the case of a jet in a cross flow is discussed.

Pre-Restoration Geomorphic Characteristics of Minebank Run, Baltimore County, Maryland, 2002-04

USGS Publications Warehouse

Doheny, Edward J.; Starsoneck, Roger J.; Mayer, Paul M.; Striz, Elise A.

2007-01-01

Data collected from 2002 through 2004 were used to assess geomorphic characteristics and geomorphic changes over time in a selected reach of Minebank Run, a small urban watershed near Towson, Maryland, prior to its physical restoration in 2004 and 2005. Longitudinal profiles of the channel bed, water surface, and bank features were developed from field surveys. Changes in cross-section geometry between field surveys were documented. Grain-size distributions for the channel bed and banks were developed from pebble counts and laboratory analyses. Net changes in the elevation of the channel bed over time were documented at selected locations. Rosgen Stream Classification was used to classify the stream channel according to morphological measurements of slope, entrenchment ratio, width-to-depth ratio, sinuosity, and median-particle diameter of the channel materials. An analysis of boundary shear stress in the vicinity of the streamflow-gaging station was conducted by use of hydraulic variables computed from cross-section surveys and slope measurements derived from crest-stage gages in the study reach. Analysis of the longitudinal profiles indicated noticeable changes in the percentage and distribution of riffles, pools, and runs through the study reach between 2002 and 2004. Despite major changes to the channel profile as a result of storm runoff events, the overall slope of the channel bed, water surface, and bank features remained constant at about 1 percent. The cross-sectional surveys showed net increases in cross-sectional area, mean depth, and channel width at several locations between 2002 and 2004, which indicate channel degradation and widening. Two locations were identified where significant amounts of sediment were being stored in the study reach. Data from scour chains identified several locations where maximum scour ranged from 1.0-1.4 feet during storm events. Bank retreat varied widely throughout the study reach and ranged from 0.2 feet to as much as 7.9 feet. Sequential measurements of bed elevation in selected locations indicated as much as 2 feet of channel degradation in one location during a storm event in May 2004 and identified pulses of sediment that were gradually transported through the study reach during the monitoring period. Particle-size analyses of channel bed materials indicated a median particle diameter of 20.5 millimeters (coarse gravel) for the study reach, with more than 24 percent being sand particles (greater than 0.062 millimeters). Analyses of bank samples showed finer-grained material composing the channel banks, predominantly silt/clay or a mixture of silt/clay (less than 0.062 millimeters) and very fine to coarse sand. The Minebank Run stream channel was classified as a B4c channel, based on morphological descriptions from the Rosgen Stream Classification System. The B4c classification describes a single-thread stream channel with a moderate entrenchment ratio of 1.4 to 2.2; a width-to-depth ratio greater than 12; moderate sinuosity of 1.2 or greater; a water-surface slope of less than 2 percent; and a median-particle diameter in the gravel range of 2 to 64 millimeters. Analysis of boundary shear stress indicated larger mean velocities and boundary shear stress values for Minebank Run when compared to relations for non-urban B channel types developed by Rosgen. The slope of the regression line for mean velocity versus boundary shear stress at Minebank Run was considerably less than slopes developed by Rosgen for non-urban channel types. This indicates that relatively small increases in mean velocity can result in large increases in boundary shear stress in stream channels with highly developed watersheds, such as Minebank Run.

Stream profile analysis using a step backwater model for selected reaches in the Chippewa Creek basin in Medina, Wayne, and Summit Counties, Ohio

USGS Publications Warehouse

Straub, David E.; Ebner, Andrew D.

2011-01-01

The USGS, in cooperation with the Chippewa Subdistrict of the Muskingum Watershed Conservancy District, performed hydrologic and hydraulic analyses for selected reaches of three streams in Medina, Wayne, Stark, and Summit Counties in northeast Ohio: Chippewa Creek, Little Chippewa Creek, and River Styx. This study was done to facilitate assessment of various alternatives for mitigating flood hazards in the Chippewa Creek basin. StreamStats regional regression equations were used to estimate instantaneous peak discharges approximately corresponding to bankfull flows. Explanatory variables used in the regression equations were drainage area, main-channel slope, and storage area. Hydraulic models were developed to determine water-surface profiles along the three stream reaches studied for the bankfull discharges established in the hydrologic analyses. The HEC-RAS step-backwater hydraulic analysis model was used to determine water-surface profiles for the three streams. Starting water-surface elevations for all streams were established using normal depth computations in the HEC-RAS models. Cross-sectional elevation data, hydraulic-structure geometries, and roughness coefficients were collected in the field and (along with peak-discharge estimates) used as input for the models. Reach-averaged reductions in water-surface elevations ranged from 0.11 to 1.29 feet over the four roughness coefficient reduction scenarios.

Characterizing the surface charge of synthetic nanomembranes by the streaming potential method

PubMed Central

Datta, Subhra; Conlisk, A. T.; Kanani, Dharmesh M.; Zydney, Andrew L.; Fissell, William H.; Roy, Shuvo

2010-01-01

The inference of the surface charge of polyethylene glycol (PEG)-coated and uncoated silicon membranes with nanoscale pore sizes from streaming potential measurements in the presence of finite electric double layer (EDL) effects is studied theoretically and experimentally. The developed theoretical model for inferring the pore wall surface charge density from streaming potential measurements is applicable to arbitrary pore cross-sectional shapes and accounts for the effect of finite salt concentration on the ionic mobilities and the thickness of the deposited layer of PEG. Theoretical interpretation of the streaming potential data collected from silicon membranes having nanoscale pore sizes, with/without pore wall surface modification with PEG, indicates that finite electric double layer (EDL) effects in the pore-confined electrolyte significantly affect the interpretation of the membrane charge and that surface modification with PEG leads to a reduction in the pore wall surface charge density. The theoretical model is also used to study the relative significance of the following uniquely nanoscale factors affecting the interpretation of streaming potential in moderate to strongly charged pores: altered net charge convection by applied pressure differentials, surface-charge effects on ionic conduction, and electroosmotic convection of charges. PMID:20462592

Ecological condition of the East Fork of the Gila River and selected tributaries: Gila National Forest, New Mexico

Treesearch

Robert D. Ohmart

1996-01-01

Ecological condition of riparian habitats along the East Fork of the Gila River, Main Diamond Creek, lower South Diamond Creek, and Black Canyon Creek are all in very heavily degraded condition. Channel cross-sections show extensive entrenchment, high width-to-depth ratios, and numerous reaches where banks are sloughing into the stream, especially on the East Fork of...

Use of airborne near-infrared LiDAR for determining channel cross-section characteristics and monitoring aquatic habitat in Pacific Northwest rivers: A preliminary analysis [Chapter 6

Treesearch

Russell N. Faux; John M. Buffington; M. German Whitley; Steve H. Lanigan; Brett B. Roper

2009-01-01

Aquatic habitat monitoring is being conducted by numerous organizations in many parts of the Pacific Northwest to document physical and biological conditions of stream reaches as part of legal- and policy-mandated environmental assessments. Remote sensing using discrete-return, near-infrared, airborne LiDAR (Light Detection and Ranging) and high-resolution digital...

Stream stability at highway structures.

DOT National Transportation Integrated Search

1995-11-01

This document provides guidelines for identifying stream instability problems at highway stream crossings and for the selection and design of appropriate countermeasures to mitigate potential damages to bridges and other highway components at stream ...

Cross-Stream PIV Measurements of Jets With Internal Lobed Mixers

NASA Technical Reports Server (NTRS)

Bridges, James; Wernet, Mark P.

2004-01-01

With emphasis being placed on enhanced mixing of jet plumes for noise reduction and on predictions of jet noise based upon turbulent kinetic energy, unsteady measurements of jet plumes are a very important part of jet noise studies. Given that hot flows are of most practical interest, optical techniques such as Particle Image Velocimetry (PIV) are applicable. When the flow has strong azimuthal features, such as those generated by chevrons or lobed mixers, traditional PIV, which aligns the measurement plane parallel to the dominant flow direction is very inefficient, requiring many planes of data to be acquired and stacked up to produce the desired flow cross-sections. This paper presents PIV data acquired in a plane normal to the jet axis, directly measuring the cross-stream gradients and features of an internally mixed nozzle operating at aircraft engine flow conditions. These nozzle systems included variations in lobed mixer penetration, lobe count, lobe scalloping, and nozzle length. Several cases validating the accuracy of the PIV data are examined along with examples of its use in answering questions about the jet noise generation processes in these nozzles. Of most interest is the relationship of low frequency aft-directed noise with turbulence kinetic energy and mean velocity.

An experimental study of the structure and acoustic field of a jet in a cross stream. [Ames 7-ft by 10-ft wind tunnel tests

NASA Technical Reports Server (NTRS)

Camelier, I.; Karamcheti, K.

1976-01-01

The plane of symmetry of a high speed circular jet was surveyed to measure the mean and turbulent velocity fields by using constant temperature hot wire anemometry. The intensity of the noise radiated from the jet was determined in the tunnel test section by utilizing the cross-correlation at a particular time delay between the signals of two microphones suitably located along a given direction. Experimental results indicate that the turbulent intensity inside the crossflow jet increases by a factor of (1 + 1/2) as compared to the turbulent intensity of the same jet under free conditions, with r indicating the ratio of the jet velocity by the cross stream velocity. The peak observed in the turbulence spectra obtained inside the potential core of the jet has a frequency that increases by the same factor with respect to the corresponding frequency measured in the case of the free jet. The noise radiated by the jet becomes more intense as the crossflow velocity increases. The measured acoustic intensity of the crossflow jet is higher than the value which would be expected from the increase of the turbulent intensity only.

Semi-empirical analysis of liquid fuel distribution downstream of a plain orifice injector under cross-stream air flow

NASA Astrophysics Data System (ADS)

Cao, M.-H.; Jiang, H.-K.; Chin, J.-S.

1982-04-01

An improved flat-fan spray model is used for the semi-empirical analysis of liquid fuel distribution downstream of a plain orifice injector under cross-stream air flow. The model assumes that, due to the aerodynamic force of the high-velocity cross air flow, the injected fuel immediately forms a flat-fan liquid sheet perpendicular to the cross flow. Once the droplets have been formed, the trajectories of individual droplets determine fuel distribution downstream. Comparison with test data shows that the proposed model accurately predicts liquid fuel distribution at any point downstream of a plain orifice injector under high-velocity, low-temperature uniform cross-stream air flow over a wide range of conditions.

Verification of roughness coefficients for selected natural and constructed stream channels in Arizona

USGS Publications Warehouse

Phillips, Jeff V.; Ingersoll, Todd L.

1998-01-01

Physical and hydraulic characteristics are presented for 14 river and canal reaches in Arizona for which 37 roughness coefficients have been determined. The verified roughness coefficients which ranged from 0.017 to 0.067, were computed from discharges, channel geometry, and water-surface profiles measured at each of the sites. The information given for each stream segment includes bed and bank descriptions, data tables showing hydraulic components, a plan view, cross-section plots, and color photographs that can be used as a comparison aid in determining roughness coefficients for similarly channeled streams. Relations derived from the data presented relate Manning's roughness coefficient (n) to various hydraulic components. For gravel-bed streams, verified roughness coefficients are related to median grain size of the bed material and hydraulic radius resulting in an equation that can be used to transfer results to similar dry-land channels. The equation developed for base values of n for gravel-bed channels in Arizona is significantly different from similarly derived equations for other regions of the United States and the world.

The StreamCat Dataset: Accumulated Attributes for NHDPlusV2 Catchments (Version 2.1) for the Conterminous United States: Road and Stream Intersections

EPA Pesticide Factsheets

This dataset represents the density of road and stream crossings within individual, local NHDPlusV2 catchments and upstream, contributing watersheds. Attributes of the landscape layer were calculated for every local NHDPlusV2 catchment and then accumulated to provide watershed-level metrics. (see Data Sources for links to NHDPlusV2 data and metadata) The landscape layer (raster) was developed by James Falcone of the USGS. US Census TIGER 2000 line files of roads and the NHDPlusV1 line files of all streams were converted to 30-meter grids where the presence of a street or stream was a 1 and everything else a 0. These were intersected and anything that was a 1 in both grids is the result. The density of road and stream crossings (crossings / square kilometer) were summarized to produce local catchment-level and watershed-level metrics as a continuous data type (see Data Structure and Attribute Information for a description).

Road crossing designs and their impact on fish assemblages of Great Plains streams

USGS Publications Warehouse

Bouska, Wesley W.; Paukert, Craig P.

2010-01-01

A mark-recapture field study was conducted to determine fish passage at 5 concrete box culverts and 5 low-water crossings (concrete slabs vented by culverts) as well as 10 control sites (below a natural riffle) in Flint Hills streams of northeastern Kansas. Additionally, we tested the upstream passage of four fish species native to Great Plains streams (Topeka shiner Notropis topeka, green sunfish Lepomis cyanellus, red shiner Cyprinella lutrensis, and southern redbelly dace Phoxinus erythrogaster) through three simulated crossing designs (box culverts, round corrugated culverts, and natural rock riffles) at water velocities of 0.1 to 1.1 m/s in an experimental stream. The field study indicated that cyprinids were twice as likely to move upstream of box culverts than low-water crossings and 1.4 times as likely to move upstream of control reaches than any crossing type. The best models indicated that the proportion of cyprinids that moved upstream increased with decreased culvert slope and length, perching, and increased culvert width. Our controlled experiment indicated that fish can move through velocities up to 1.1 m/s in a 1.86-m simulated stream and that the proportion of fish that moved upstream did not differ among crossing designs for southern redbelly dace, green sunfish, or Topeka shiner; however, natural rock riffles had lower proportional movements (mean = 0.19) than the box (0.38) or corrugated culvert designs (0.43) for red shiners. Water velocity did not affect the proportional upstream movement of any species except that of Topeka shiners, which increased with water velocity. Crossing design alone may not determine fish passage, and water velocities up to 1.1 m/s may not affect the passage of many Great Plains fishes. Barriers to fish movement may be the result of other factors (e.g., perching, slope, and crossing length). The use of properly designed and installed crossings has promise in conserving Great Plains stream fishes.

Modelling the flooding capacity of a Polish Carpathian river: A comparison of constrained and free channel conditions

NASA Astrophysics Data System (ADS)

Czech, Wiktoria; Radecki-Pawlik, Artur; Wyżga, Bartłomiej; Hajdukiewicz, Hanna

2016-11-01

The gravel-bed Biała River, Polish Carpathians, was heavily affected by channelization and channel incision in the twentieth century. Not only were these impacts detrimental to the ecological state of the river, but they also adversely modified the conditions of floodwater retention and flood wave passage. Therefore, a few years ago an erodible corridor was delimited in two sections of the Biała to enable restoration of the river. In these sections, short, channelized reaches located in the vicinity of bridges alternate with longer, unmanaged channel reaches, which either avoided channelization or in which the channel has widened after the channelization scheme ceased to be maintained. Effects of these alternating channel morphologies on the conditions for flood flows were investigated in a study of 10 pairs of neighbouring river cross sections with constrained and freely developed morphology. Discharges of particular recurrence intervals were determined for each cross section using an empirical formula. The morphology of the cross sections together with data about channel slope and roughness of particular parts of the cross sections were used as input data to the hydraulic modelling performed with the one-dimensional steady-flow HEC-RAS software. The results indicated that freely developed cross sections, usually with multithread morphology, are typified by significantly lower water depth but larger width and cross-sectional flow area at particular discharges than single-thread, channelized cross sections. They also exhibit significantly lower average flow velocity, unit stream power, and bed shear stress. The pattern of differences in the hydraulic parameters of flood flows apparent between the two types of river cross sections varies with the discharges of different frequency, and the contrasts in hydraulic parameters between unmanaged and channelized cross sections are most pronounced at low-frequency, high-magnitude floods. However, because of the deep incision of the river, both cross section types are typified by a similar, low potential for the retention of floodwater in floodplain areas. The study indicated that even though river restoration has only begun here, it already brings beneficial effects for flood risk management, reducing flow energy and shear forces exerted on the bed and banks of the channel in unmanaged river reaches. Only within wide, unmanaged channel reaches can the flows of low-frequency, high-magnitude floods be conveyed with relatively low shear forces exerted on the channel boundary. In contrast, in channelized reaches, flow velocity and shear forces are substantially higher, inevitably causing bank erosion and channel incision.

Different roles of electron beam in two stream instability in an elliptical waveguide for generation and amplification of THz electromagnetic waves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Safari, S.; Jazi, B., E-mail: jaziada@kashanu.ac.ir; Jahanbakht, S.

2016-08-15

In this work, two stream instability in a metallic waveguide with elliptical cross-section and with a hollow annular dielectric layer is studied for generation and amplification of THz electromagnetic waves. Dispersion relation of waves and their dependents to geometric dimensions and characteristics of the electron beam are analyzed. In continuation, the diagrams of growth rate for some operating frequencies are presented, so that effective factors on the growth rates, such as geometrical dimensions, dielectric constant of dielectric layer, accelerating voltage, and applied current intensity are analyzed. It is shown that while an electron beam is responsible for instability, another electronmore » beam plays a stabilizing role.« less

Hydroliquefaction of coal

DOEpatents

Sze, Morgan C.; Schindler, Harvey D.

1982-01-01

Coal is catalytically hydroliquefied by passing coal dispersed in a liquefaction solvent and hydrogen upwardly through a plurality of parallel expanded catalyst beds, in a single reactor, in separate streams, each having a cross-sectional flow area of no greater than 255 inches square, with each of the streams through each of the catalyst beds having a length and a liquid and gas superficial velocity to maintain an expanded catalyst bed and provide a Peclet Number of at least 3. If recycle is employed, the ratio of recycle to total feed (coal and liquefaction solvent) is no greater than 2:1, based on volume. Such conditions provide for improved selectivity to liquid product to thereby reduce hydrogen consumption. The plurality of beds are formed by partitions in the reactor.

On the cross-stream spectral method for the Orr-Sommerfeld equation

NASA Technical Reports Server (NTRS)

Zorumski, William E.; Hodge, Steven L.

1993-01-01

Cross-stream models are defined as solutions to the Orr-Sommerfeld equation which are propagating normal to the flow direction. These models are utilized as a basis for a Hilbert space to approximate the spectrum of the Orr-Sommerfeld equation with plane Poiseuille flow. The cross-stream basis leads to a standard eigenvalue problem for the frequencies of Poiseuille flow instability waves. The coefficient matrix in the eigenvalue problem is shown to be the sum of a real matrix and a negative-imaginary diagonal matrix which represents the frequencies of the cross-stream modes. The real coefficient matrix is shown to approach a Toeplitz matrix when the row and column indices are large. The Toeplitz matrix is diagonally dominant, and the diagonal elements vary inversely in magnitude with diagonal position. The Poiseuille flow eigenvalues are shown to lie within Gersgorin disks with radii bounded by the product of the average flow speed and the axial wavenumber. It is shown that the eigenvalues approach the Gersgorin disk centers when the mode index is large, so that the method may be used to compute spectra with an essentially unlimited number of elements. When the mode index is large, the real part of the eigenvalue is the product of the axial wavenumber and the average flow speed, and the imaginary part of the eigen value is identical to the corresponding cross-stream mode frequency. The cross-stream method is numerically well-conditioned in comparison to Chebyshev based methods, providing equivalent accuracy for small mode indices and superior accuracy for large indices.

Slope-Area Computation Program Graphical User Interface 1.0—A Preprocessing and Postprocessing Tool for Estimating Peak Flood Discharge Using the Slope-Area Method

USGS Publications Warehouse

Bradley, D. Nathan

2012-01-01

The slope-area method is a technique for estimating the peak discharge of a flood after the water has receded (Dalrymple and Benson, 1967). This type of discharge estimate is called an “indirect measurement” because it relies on evidence left behind by the flood, such as high-water marks (HWMs) on trees or buildings. These indicators of flood stage are combined with measurements of the cross-sectional geometry of the stream, estimates of channel roughness, and a mathematical model that balances the total energy of the flow between cross sections. This is in contrast to a “direct” measurement of discharge during the flood where cross-sectional area is measured and a current meter or acoustic equipment is used to measure the water velocity. When a direct discharge measurement cannot be made at a gage during high flows because of logistics or safety reasons, an indirect measurement of a peak discharge is useful for defining the high-flow section of the stage-discharge relation (rating curve) at the stream gage, resulting in more accurate computation of high flows. The Slope-Area Computation program (SAC; Fulford, 1994) is an implementation of the slope-area method that computes a peak-discharge estimate from inputs of water-surface slope (from surveyed HWMs), channel geometry, and estimated channel roughness. SAC is a command line program written in Fortran that reads input data from a formatted text file and prints results to another formatted text file. Preparing the input file can be time-consuming and prone to errors. This document describes the SAC graphical user interface (GUI), a crossplatform “wrapper” application that prepares the SAC input file, executes the program, and helps the user interpret the output. The SAC GUI is an update and enhancement of the slope-area method (SAM; Hortness, 2004; Berenbrock, 1996), an earlier spreadsheet tool used to aid field personnel in the completion of a slope-area measurement. The SAC GUI reads survey data, develops a plan-view plot, water-surface profile, cross-section plots, and develops the SAC input file. The SAC GUI also develops HEC-2 files that can be imported into HEC–RAS.

Design for fish passage at roadway-stream crossings : synthesis report.

DOT National Transportation Integrated Search

2007-06-01

Cataloging and synthesizing existing methods for the design of roadway-stream crossings for fish passage began in : January 2005 with an extensive literature review covering the topics of culvert design and assessment to facilitate : fish passage. A ...

Determination of biologically significant hydrologic condition metrics in urbanizing watersheds: an empirical analysis over a range of environmental settings

USGS Publications Warehouse

Steuer, Jeffrey J.; Stensvold, Krista A.; Gregory, Mark B.

2010-01-01

We investigated the relations among 83 hydrologic condition metrics (HCMs) and changes in algal, invertebrate, and fish communities in five metropolitan areas across the continental United States. We used a statistical approach that employed Spearman correlation and regression tree analysis to identify five HCMs that are strongly associated with observed biological variation along a gradient of urbanization. The HCMs related to average flow magnitude, high-flow magnitude, high-flow event frequency, high-flow duration, and rate of change of stream cross-sectional area were most consistently associated with changes in aquatic communities. Although our investigation used an urban gradient design with short hydrologic periods of record (≤1 year) of hourly cross-sectional area time series, these five HCMs were consistent with previous investigations using long-term daily-flow records. The ecological sampling day often was included in the hydrologic period. Regression tree models explained up to 73, 92, and 79% of variance for specific algal, invertebrate, and fish community metrics, respectively. National models generally were not as statistically significant as models for individual metropolitan areas. High-flow event frequency, a hydrologic metric found to be transferable across stream type and useful for classifying habitat by previous research, was found to be the most ecologically relevant HCM; transformation by precipitation increased national-scale applicability. We also investigated the relation between measures of stream flashiness and land-cover indicators of urbanization and found that land-cover characteristic and pattern variables, such as road density, percent wetland, and proximity of developed land, were strongly related to HCMs at both a metropolitan and national scale and, therefore, may be effective land-use management options in addition to wholesale impervious-area reduction.

Impact of debris dams on hyporheic interaction along a semi-arid stream

NASA Astrophysics Data System (ADS)

Lautz, Laura K.; Siegel, Donald I.; Bauer, Robert L.

2006-01-01

Hyporheic exchange increases the potential for solute retention in streams by slowing downstream transport and increasing solute contact with the substrate. Hyporheic exchange may be a major mechanism to remove nutrients in semi-arid watersheds, where livestock have damaged stream riparian zones and contributed nutrients to stream channels. Debris dams, such as beaver dams and anthropogenic log dams, may increase hyporheic interactions by slowing stream water velocity, increasing flow complexity and diverting water to the subsurface.Here, we report the results of chloride tracer injection experiments done to evaluate hyporheic interaction along a 320 m reach of Red Canyon Creek, a second order stream in the semi-arid Wind River Range of Wyoming. The study site is part of a rangeland watershed managed by The Nature Conservancy of Wyoming, and used as a hydrologic field site by the University of Missouri Branson Geologic Field Station. The creek reach we investigated has debris dams and tight meanders that hypothetically should enhance hyporheic interaction. Breakthrough curves of chloride measured during the field experiment were modelled with OTIS-P, a one-dimensional, surface-water, solute-transport model from which we extracted the storage exchange rate and cross-sectional area of the storage zone As for hyporheic exchange. Along gaining reaches of the stream reach, short-term hyporheic interactions associated with debris dams were comparable to those associated with severe meanders. In contrast, along the non-gaining reach, stream water was diverted to the subsurface by debris dams and captured by large-scale near-stream flow paths. Overall, hyporheic exchange rates along Red Canyon Creek during snowmelt recession equal or exceed exchange rates observed during baseflow at other streams.

Effects of upland disturbance and instream restoration on hydrodynamics and ammonium uptake in headwater streams

USGS Publications Warehouse

Roberts, B.J.; Mulholland, P.J.; Houser, J.N.

2007-01-01

Delivery of water, sediments, nutrients, and organic matter to stream ecosystems is strongly influenced by the catchment of the stream and can be altered greatly by upland soil and vegetation disturbance. At the Fort Benning Military Installation (near Columbus, Georgia), spatial variability in intensity of military training results in a wide range of intensities of upland disturbance in stream catchments. A set of 8 streams in catchments spanning this upland disturbance gradient was selected for investigation of the impact of disturbance intensity on hydrodynamics and nutrient uptake. The size of transient storage zones and rates of NH4+ uptake in all study streams were among the lowest reported in the literature. Upland disturbance did not appear to influence stream hydrodynamics strongly, but it caused significant decreases in instream nutrient uptake. In October 2003, coarse woody debris (CWD) was added to 1/2 of the study streams (spanning the disturbance gradient) in an attempt to increase hydrodynamic and structural complexity, with the goals of enhancing biotic habitat and increasing nutrient uptake rates. CWD additions had positive short-term (within 1 mo) effects on hydrodynamic complexity (water velocity decreased and transient storage zone cross-sectional area, relative size of the transient storage zone, fraction of the median travel time attributable to transient storage over a standardized length of 200 m, and the hydraulic retention factor increased) and nutrient uptake (NH4+ uptake rates increased). Our results suggest that water quality in streams with intense upland disturbances can be improved by enhancing instream biotic nutrient uptake capacity through measures such as restoring stream CWD. ?? 2007 by The North American Benthological Society.

Design manual for low water stream crossings.

DOT National Transportation Integrated Search

1983-10-01

The purpose of this manual is to provide design guidelines for : low water stream crossings (LWSCs). Rigid criteria for determining the : applicability of a LWSC to a given site are not established since each : site is unique in terms of physical, so...

Stream instability countermeasures applied at Kansas Department of Transportation highway structures.

DOT National Transportation Integrated Search

2008-11-01

This project considered stream instability countermeasures used by the Kansas Department of Transportation (KDOT) to protect the highway infrastructure at stream crossings from changes due to the dynamic nature of streams. Site visits were made to 13...

Apparatus and method for burning a lean, premixed fuel/air mixture with low NOx emission

DOEpatents

Kostiuk, Larry W.; Cheng, Robert K.

1996-01-01

An apparatus for enabling a burner to stably burn a lean fuel/air mixture. The burner directs the lean fuel/air mixture in a stream. The apparatus comprises an annular flame stabilizer; and a device for mounting the flame stabilizer in the fuel/air mixture stream. The burner may include a body having an internal bore, in which case, the annular flame stabilizer is shaped to conform to the cross-sectional shape of the bore, is spaced from the bore by a distance greater than about 0.5 mm, and the mounting device mounts the flame stabilizer in the bore. An apparatus for burning a gaseous fuel with low NOx emissions comprises a device for premixing air with the fuel to provide a lean fuel/air mixture; a nozzle having an internal bore through which the lean fuel/air mixture passes in a stream; and a flame stabilizer mounted in the stream of the lean fuel/air mixture. The flame stabilizer may be mounted in the internal bore, in which case, it is shaped and is spaced from the bore as just described. In a method of burning a lean fuel/air mixture, a lean fuel/air mixture is provided, and is directed in a stream; an annular eddy is created in the stream of the lean fuel/air mixture; and the lean fuel/air mixture is ignited at the eddy.

Road crossings as barriers to small-stream fish movement

Treesearch

Melvin L. Warren; Mitzi G. Pardew

1998-01-01

The authors used mark-recapture techniques to examine the effects of four types of road crossings on fish movement during spring base flows and summer low flows in small streams of the Ouachita Mountains, west-central Arkansas. The authors assessed movement for 21 fish species in seven families through culvert, slab, open-box, and ford crossings and through natural...

Effects of geomorphology, habitat, and spatial location on fish assemblages in a watershed in Ohio, USA.

PubMed

D'Ambrosio, Jessica L; Williams, Lance R; Witter, Jonathan D; Ward, Andy

2009-01-01

In this paper, we evaluate relationships between in-stream habitat, water chemistry, spatial distribution within a predominantly agricultural Midwestern watershed and geomorphic features and fish assemblage attributes and abundances. Our specific objectives were to: (1) identify and quantify key environmental variables at reach and system wide (watershed) scales; and (2) evaluate the relative influence of those environmental factors in structuring and explaining fish assemblage attributes at reach scales to help prioritize stream monitoring efforts and better incorporate all factors that influence aquatic biology in watershed management programs. The original combined data set consisted of 31 variables measured at 32 sites, which was reduced to 9 variables through correlation and linear regression analysis: stream order, percent wooded riparian zone, drainage area, in-stream cover quality, substrate quality, gradient, cross-sectional area, width of the flood prone area, and average substrate size. Canonical correspondence analysis (CCA) and variance partitioning were used to relate environmental variables to fish species abundance and assemblage attributes. Fish assemblages and abundances were explained best by stream size, gradient, substrate size and quality, and percent wooded riparian zone. Further data are needed to investigate why water chemistry variables had insignificant relationships with IBI scores. Results suggest that more quantifiable variables and consideration of spatial location of a stream reach within a watershed system should be standard data incorporated into stream monitoring programs to identify impairments that, while biologically limiting, are not fully captured or elucidated using current bioassessment methods.

Comparison of water-quality samples collected by siphon samplers and automatic samplers in Wisconsin

USGS Publications Warehouse

Graczyk, David J.; Robertson, Dale M.; Rose, William J.; Steur, Jeffrey J.

2000-01-01

In small streams, flow and water-quality concentrations often change quickly in response to meteorological events. Hydrologists, field technicians, or locally hired stream ob- servers involved in water-data collection are often unable to reach streams quickly enough to observe or measure these rapid changes. Therefore, in hydrologic studies designed to describe changes in water quality, a combination of manual and automated sampling methods have commonly been used manual methods when flow is relatively stable and automated methods when flow is rapidly changing. Auto- mated sampling, which makes use of equipment programmed to collect samples in response to changes in stage and flow of a stream, has been shown to be an effective method of sampling to describe the rapid changes in water quality (Graczyk and others, 1993). Because of the high cost of automated sampling, however, especially for studies examining a large number of sites, alternative methods have been considered for collecting samples during rapidly changing stream conditions. One such method employs the siphon sampler (fig. 1). also referred to as the "single-stage sampler." Siphon samplers are inexpensive to build (about $25- $50 per sampler), operate, and maintain, so they are cost effective to use at a large number of sites. Their ability to collect samples representing the average quality of water passing though the entire cross section of a stream, however, has not been fully demonstrated for many types of stream sites.

Influence of geomorphological properties and stage on in-stream travel time

NASA Astrophysics Data System (ADS)

Åkesson, Anna; Wörman, Anders

2014-05-01

The travel time distribution within stream channels is known to vary non-linearly with stage (discharge), depending on the combined effects of geomorphologic, hydrodynamic and kinematic dispersions. This non-linearity, implying that stream network travel time generally decreases with increasing discharge is a factor that is important to account for in hydrological modelling - especially when making peak flow predictions where uncertainty is often high and large values can be at risk. Through hydraulic analysis of several stream networks, we analyse how travel time distributions varies with discharge. The principal focus is the coupling to the geomorphologic properties of stream networks with the final goal being to use this physically based information as a parameterisation tool of the streamflow component of hydrologic models. For each of the studied stream networks, a 1D, steady-state, distributed routing model was set up to determine the velocities in each reach during different flow conditions. Although the model (based in the Manning friction formula) is built on the presence of uniform conditions within sub-reaches, the model can in the stream network scale be considered to include effects of non-uniformity as supercritical conditions in sections of the stream network give rise to backwater effects that reduce the flow velocities in upstream reaches in the stream. By coupling the routing model to a particle tracking routine tracing water "parcels" through the stream network, the average travel time within the stream network can be determined quantitatively for different flow conditions. The data used to drive the model is digitised stream network maps, topographical data (DEMs). The model is not calibrated in any way, but is run for with different sets of parameters representing a span of possible friction coefficients and cross-sectional geometries as this information is not generally known. The routing model is implemented in several different stream networks (representing catchments of the spatial scale of a few hundred km2) in different geographic regions in Sweden displaying different geomorphological properties. Results show that the geomorphological properties (data that is often available in the form of maps and/or DEMs) of individual stream networks have major influence on the stream network travel times. By coupling the geomorphological information to general expressions for stage dependency, catchment-specific relationships of how the travel times within stream networks can be determined. Basing the parameterisation procedure of a hydrological model in physical catchment properties and process understanding rather than statistical parameterisation (based in how a catchment has responded in the past) - is believed to lead to more reliable hydrological predictions - during extreme conditions as well as during changing conditions such as climate change and landscape modifications, and/or when making predictions in ungauged basins.

Assessment of wadeable stream resources in the driftless area ecoregion in Western Wisconsin using a probabilistic sampling design.

PubMed

Miller, Michael A; Colby, Alison C C; Kanehl, Paul D; Blocksom, Karen

2009-03-01

The Wisconsin Department of Natural Resources (WDNR), with support from the U.S. EPA, conducted an assessment of wadeable streams in the Driftless Area ecoregion in western Wisconsin using a probabilistic sampling design. This ecoregion encompasses 20% of Wisconsin's land area and contains 8,800 miles of perennial streams. Randomly-selected stream sites (n = 60) equally distributed among stream orders 1-4 were sampled. Watershed land use, riparian and in-stream habitat, water chemistry, macroinvertebrate, and fish assemblage data were collected at each true random site and an associated "modified-random" site on each stream that was accessed via a road crossing nearest to the true random site. Targeted least-disturbed reference sites (n = 22) were also sampled to develop reference conditions for various physical, chemical, and biological measures. Cumulative distribution function plots of various measures collected at the true random sites evaluated with reference condition thresholds, indicate that high proportions of the random sites (and by inference the entire Driftless Area wadeable stream population) show some level of degradation. Study results show no statistically significant differences between the true random and modified-random sample sites for any of the nine physical habitat, 11 water chemistry, seven macroinvertebrate, or eight fish metrics analyzed. In Wisconsin's Driftless Area, 79% of wadeable stream lengths were accessible via road crossings. While further evaluation of the statistical rigor of using a modified-random sampling design is warranted, sampling randomly-selected stream sites accessed via the nearest road crossing may provide a more economical way to apply probabilistic sampling in stream monitoring programs.

Determining long time-scale hyporheic zone flow paths in Antarctic streams

USGS Publications Warehouse

Gooseff, M.N.; McKnight, Diane M.; Runkel, R.L.; Vaughn, B.H.

2003-01-01

In the McMurdo Dry Valleys of Antarctica, glaciers are the source of meltwater during the austral summer, and the streams and adjacent hyporheic zones constitute the entire physical watershed; there are no hillslope processes in these systems. Hyporheic zones can extend several metres from each side of the stream, and are up to 70 cm deep, corresponding to a lateral cross-section as large as 12 m2, and water resides in the subsurface year around. In this study, we differentiate between the near-stream hyporheic zone, which can be characterized with stream tracer experiments, and the extended hyporheic zone, which has a longer time-scale of exchange. We sampled stream water from Green Creek and from the adjacent saturated alluvium for stable isotopes of D and 18O to assess the significance and extent of stream-water exchange between the streams and extended hyporheic zones over long time-scales (days to weeks). Our results show that water residing in the extended hyporheic zone is much more isotopically enriched (up to 11??? D and 2.2??? 18O) than stream water. This result suggests a long residence time within the extended hyporheic zone, during which fractionation has occured owing to summer evaporation and winter sublimation of hyporheic water. We found less enriched water in the extended hyporheic zone later in the flow season, suggesting that stream water may be exchanged into and out of this zone, on the time-scale of weeks to months. The transient storage model OTIS was used to characterize the exchange of stream water with the extended hyporheic zone. Model results yield exchange rates (??) generally an order magnitude lower (10-5 s-1) than those determined using stream-tracer techniques on the same stream. In light of previous studies in these streams, these results suggest that the hyporheic zones in Antarctic streams have near-stream zones of rapid stream-water exchange, where 'fast' biogeochemical reactions may influence water chemistry, and extended hyporheic zones, in which slower biogeochemical reaction rates may affect stream-water chemistry at longer time-scales. Copyright ?? 2003 John Wiley & Sons, Ltd.

Streaming driven by sessile microbubbles: Explaining flow patterns and frequency response

NASA Astrophysics Data System (ADS)

Rallabandi, Bhargav; Wang, Cheng; Guo, Lin; Hilgenfeldt, Sascha

2013-11-01

Ultrasound excitation of bubbles drives powerful steady streaming flows which have found widespread applications in microfluidics, where bubbles are typically of semicircular cross section and attached to walls of the device (sessile). While bubble-driven streaming in bulk fluid is well understood, this practically relevant case presents additional complexity introduced by the wall and contact lines. We develop an asymptotic theory that takes into account the presence of the wall as well as the oscillation dynamics of the bubble, providing a complete description of the streaming flow as a function only of the driving frequency, the bubble size, and the physical properties of the fluid. We show that the coupling between different bubble oscillation modes sustains the experimentally observed streaming flow vortex pattern over a broad range of frequencies, greatly exceeding the widths of individual mode resonances. Above a threshold frequency, we predict, and observe in experiment, reversal of the flow direction. Our analytical theory can be used to guide the design of microfluidic devices, both in situations where robust flow patterns insensitive to parameter changes are desired (e.g. lab-on-a-chip sorters), and in cases where intentional modulation of the flow field appearance is key (e.g. efficient mixers). Current address: Department of Mechanical and Aerospace Engineering, Missouri University of Science and Technology.

Potential interaction between transport and stream networks over the lowland rivers in Eastern India.

PubMed

Roy, Suvendu; Sahu, Abhay Sankar

2017-07-15

Extension of transport networks supports good accessibility and associated with the development of a region. However, transport lines have fragmented the regional landscape and disturbed the natural interplay between rivers and their floodplains. Spatial analysis using multiple buffers provides information about the potential interaction between road and stream networks and their impact on channel morphology of a small watershed in the Lower Gangetic Plain. Present study is tried to understand the lateral and longitudinal disconnection in headwater stream by rural roads with the integration of geoinformatics and field survey. Significant (p < 0.001) growth of total road length and number of road-stream crossing in the last five decades (1970s-2010s) contribute to making longitudinal and lateral disconnection in the fluvial system of Kunur River Basin. Channel geometry from ten road-stream crossings shows significant (p = 0.01) differences between upstream and downstream of crossing structure and created problems like downstream scouring, increased drop height at outlet, formation of stable bars, severe bank erosion, and make barriers for river biota. The hydro-geomorphic processes are also adversely affected due to lateral disconnection and input of fine to coarse sediments from the river side growth of unpaved road (1922%). Limited streamside development, delineation of stream corridor, regular monitoring and engineering efficiency for the construction of road and road-stream crossing might be effective in managing river geomorphology and riverine landscape. Copyright © 2017 Elsevier Ltd. All rights reserved.

Transverse liquid fuel jet breakup, burning, and ignition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Hsi-shang

1990-01-01

An analytical/numerical study of the breakup, burning, and ignition of liquid fuels injected transversely into a hot air stream is conducted. The non-reacting liquid jet breakup location is determined by the local sonic point criterion first proposed by Schetz, et al. (1980). Two models, one employing analysis of an elliptical jet cross-section and the other employing a two-dimensional blunt body to represent the transverse jet, have been used for sonic point calculations. An auxiliary criterion based on surface tension stability is used as a separate means of determining the breakup location. For the reacting liquid jet problem, a diffusion flamemore » supported by a one-step chemical reaction within the gaseous boundary layer is solved along the ellipse surface in subsonic crossflow. Typical flame structures and concentration profiles have been calculated for various locations along the jet cross-section as a function of upstream Mach numbers. The integrated reaction rate along the jet cross-section is used to predict ignition position, which is found to be situated near the stagnation point. While a multi-step reaction is needed to represent the ignition process more accurately, the present calculation does yield reasonable predictions concerning ignition along a curved surface.« less

The influence of stream thermal regimes and preferential flow paths on hyporheic exchange in a glacial meltwater stream

USGS Publications Warehouse

Cozzetto, Karen D.; Bencala, Kenneth E.; Gooseff, Michael N.; McKnight, Diane M.

2013-01-01

Given projected increases in stream temperatures attributable to global change, improved understanding of relationships between stream temperatures and hyporheic exchange would be useful. We conducted two conservative tracer injection experiments in a glacial meltwater stream, to evaluate the effects of hyporheic thermal gradients on exchange processes, including preferential flow paths (PFPs). The experiments were conducted on the same day, the first (a stream injection) during a cool, morning period and the second (dual stream and hyporheic injections) during a warm, afternoon period. In the morning, the hyporheic zone was thermally uniform at 4°C, whereas by the afternoon the upper 10 cm had warmed to 6–12°C and exhibited greater temperature heterogeneity. Solute transport modeling showed that hyporheic cross-sectional areas (As) at two downstream sites were two and seven times lower during the warm experiment. Exchange metrics indicated that the hyporheic zone had less influence on downstream solute transport during the warm, afternoon experiment. Calculated hyporheic depths were less than 5 cm, contrasting with tracer detection at 10 and 25 cm depths. The hyporheic tracer arrival at one downstream site was rapid, comparable to the in-stream tracer arrival, providing evidence for PFPs. We thus propose a conceptual view of the hyporheic zone in this reach as being dominated by discrete PFPs weaving through hydraulically isolated areas. One explanation for the simultaneous increase in temperature heterogeneity and As decrease in a warmer hyporheic zone may be a flow path preferentiality feedback mechanism resulting from a combination of temperature-related viscosity decreases and streambed heterogeneity.

Cross-flow electrochemical reactor cells, cross-flow reactors, and use of cross-flow reactors for oxidation reactions

DOEpatents

Balachandran, Uthamalingam; Poeppel, Roger B.; Kleefisch, Mark S.; Kobylinski, Thaddeus P.; Udovich, Carl A.

1994-01-01

This invention discloses cross-flow electrochemical reactor cells containing oxygen permeable materials which have both electron conductivity and oxygen ion conductivity, cross-flow reactors, and electrochemical processes using cross-flow reactor cells having oxygen permeable monolithic cores to control and facilitate transport of oxygen from an oxygen-containing gas stream to oxidation reactions of organic compounds in another gas stream. These cross-flow electrochemical reactors comprise a hollow ceramic blade positioned across a gas stream flow or a stack of crossed hollow ceramic blades containing a channel or channels for flow of gas streams. Each channel has at least one channel wall disposed between a channel and a portion of an outer surface of the ceramic blade, or a common wall with adjacent blades in a stack comprising a gas-impervious mixed metal oxide material of a perovskite structure having electron conductivity and oxygen ion conductivity. The invention includes reactors comprising first and second zones seprated by gas-impervious mixed metal oxide material material having electron conductivity and oxygen ion conductivity. Prefered gas-impervious materials comprise at least one mixed metal oxide having a perovskite structure or perovskite-like structure. The invention includes, also, oxidation processes controlled by using these electrochemical reactors, and these reactions do not require an external source of electrical potential or any external electric circuit for oxidation to proceed.

A new approach to flow through a region bounded by two ellipses of the same ellipticity

NASA Astrophysics Data System (ADS)

Lal, K.; Chorlton, F.

1981-05-01

A new approach is presented to calculate steady flow of a laminar viscous incompressible fluid through a channel whose cross section is bounded by two ellipses with the same ellipticity. The Milne-Thomas approach avoids the stream function and is similar to the Rayleigh-Ritz approximation process of the calculus of variations in its first satisfying boundary conditions and then adjusting constants or multiplying functions to fit the differential equation.

Active Urbanization and Channel Adjustment in Apple Creek, Appleton, WI

NASA Astrophysics Data System (ADS)

Clark, J. J.

2002-12-01

Headwaters of the Apple Creek watershed have been and continue to be rapidly developed as part of the City of Appleton's long-term growth plan. Concurrent with early development, and prior to development over the past 4 years, two regional stormwater management facilities were constructed. Cross-sectional surveys and core transects were used to determine channel response to urbanization mitigated by stormwater management. The reach immediately downstream of the first pond complex has a narrow, but well established, wooded riparian zone and has not changed in size or shape over the past two years. An engineered reach approximately one mile downstream, however has exhibited widespread bed aggradation. Cross-sectional area decreased an average of 51% over the past four years. Despite the use of sediment and erosion control BMPs, sediment concentrations exceeding 1000 mg/L during base flow are not uncommon downstream of construction sites adjacent to the stream. The artificially widened channel, a reduction in stream gradient, and the backwater effect from downstream ponds caused much of this sediment to remain within the engineered reach. It is estimated that approximately 21,000 Mg of sediment is stored in this mile-long reach. As this sediment migrates downstream, the forebay of the second set of stormwater ponds will begin to fill, reducing storage capacity and thereby limiting its effectiveness in mitigating peak discharges and sequestering nutrients.

Field assessment of noncontact stream gauging using portable surface velocity radars (SVR)

NASA Astrophysics Data System (ADS)

Welber, Matilde; Le Coz, Jérôme; Laronne, Jonathan B.; Zolezzi, Guido; Zamler, Daniel; Dramais, Guillaume; Hauet, Alexandre; Salvaro, Martino

2016-02-01

The applicability of a portable, commercially available surface velocity radar (SVR) for noncontact stream gauging was evaluated through a series of field-scale experiments carried out in a variety of sites and deployment conditions. Comparisons with various concurrent techniques showed acceptable agreement with velocity profiles, with larger uncertainties close to the banks. In addition to discharge error sources shared with intrusive velocity-area techniques, SVR discharge estimates are affected by flood-induced changes in the bed profile and by the selection of a depth-averaged to surface velocity ratio, or velocity coefficient (α). Cross-sectional averaged velocity coefficients showed smaller fluctuations and closer agreement with theoretical values than those computed on individual verticals, especially in channels with high relative roughness. Our findings confirm that α = 0.85 is a valid default value, with a preferred site-specific calibration to avoid underestimation of discharge in very smooth channels (relative roughness ˜ 0.001) and overestimation in very rough channels (relative roughness > 0.05). Theoretically derived and site-calibrated values of α also give accurate SVR-based discharge estimates (within 10%) for low and intermediate roughness flows (relative roughness 0.001 to 0.05). Moreover, discharge uncertainty does not exceed 10% even for a limited number of SVR positions along the cross section (particularly advantageous to gauge unsteady flood flows and very large floods), thereby extending the range of validity of rating curves.

Coaxial twin-fluid atomization with pattern air gas streams

NASA Astrophysics Data System (ADS)

Hei Ng, Chin; Aliseda, Alberto

2010-11-01

Coaxial twin-fluid atomization has numerous industrial applications, most notably fuel injection and spray coating. In the coating process of pharmaceutical tablets, the coaxial atomizing air stream is accompanied by two diametrically opposed side jets that impinge on the liquid/gas coaxial jets at an angle to produce an elliptical shape of the spray's cross section. Our study focuses on the influence of these side jets on the break up process and on the droplet velocity and diameter distribution along the cross section. The ultimate goal is to predict the size distribution and volume flux per unit area in the spray. With this predictive model, an optimal atomizing air/pattern air ratio can be found to achieve the desired coating result. This model is also crucial in scaling up the laboratory setup to production level. We have performed experiments with different atomized liquids, such as water and glycerine-water mixtures, that allow us to establish the effect of liquid viscosity, through the Ohnesorge number, in the spray characteristics. The gas Reynolds number of our experiments ranges from 9000 to 18000 and the Weber number ranges from 400 to 1600. We will present the effect of pattern air in terms of the resulting droplets size, droplet number density and velocity at various distances downstream of the nozzle where the effect of pattern air is significant.

Digital floodplain mapping and an analysis of errors involved

USGS Publications Warehouse

Hamblen, C.S.; Soong, D.T.; Cai, X.

2007-01-01

Mapping floodplain boundaries using geographical information system (GIS) and digital elevation models (DEMs) was completed in a recent study. However convenient this method may appear at first, the resulting maps potentially can have unaccounted errors. Mapping the floodplain using GIS is faster than mapping manually, and digital mapping is expected to be more common in the future. When mapping is done manually, the experience and judgment of the engineer or geographer completing the mapping and the contour resolution of the surface topography are critical in determining the flood-plain and floodway boundaries between cross sections. When mapping is done digitally, discrepancies can result from the use of the computing algorithm and digital topographic datasets. Understanding the possible sources of error and how the error accumulates through these processes is necessary for the validation of automated digital mapping. This study will evaluate the procedure of floodplain mapping using GIS and a 3 m by 3 m resolution DEM with a focus on the accumulated errors involved in the process. Within the GIS environment of this mapping method, the procedural steps of most interest, initially, include: (1) the accurate spatial representation of the stream centerline and cross sections, (2) properly using a triangulated irregular network (TIN) model for the flood elevations of the studied cross sections, the interpolated elevations between them and the extrapolated flood elevations beyond the cross sections, and (3) the comparison of the flood elevation TIN with the ground elevation DEM, from which the appropriate inundation boundaries are delineated. The study area involved is of relatively low topographic relief; thereby, making it representative of common suburban development and a prime setting for the need of accurately mapped floodplains. This paper emphasizes the impacts of integrating supplemental digital terrain data between cross sections on floodplain delineation. ?? 2007 ASCE.

Beyond cool: adapting upland streams for climate change using riparian woodlands.

PubMed

Thomas, Stephen M; Griffiths, Siân W; Ormerod, Steve J

2016-01-01

Managed adaptation could reduce the risks of climate change to the world's ecosystems, but there have been surprisingly few practical evaluations of the options available. For example, riparian woodland is advocated widely as shade to reduce warming in temperate streams, but few studies have considered collateral effects on species composition or ecosystem functions. Here, we use cross-sectional analyses at two scales (region and within streams) to investigate whether four types of riparian management, including those proposed to reduce potential climate change impacts, might also affect the composition, functional character, dynamics and energetic resourcing of macroinvertebrates in upland Welsh streams (UK). Riparian land use across the region had only small effects on invertebrate taxonomic composition, while stable isotope data showed how energetic resources assimilated by macroinvertebrates in all functional guilds were split roughly 50:50 between terrestrial and aquatic origins irrespective of riparian management. Nevertheless, streams draining the most extensive deciduous woodland had the greatest stocks of coarse particulate matter (CPOM) and greater numbers of 'shredding' detritivores. Stream-scale investigations showed that macroinvertebrate biomass in deciduous woodland streams was around twice that in moorland streams, and lowest of all in streams draining non-native conifers. The unexpected absence of contrasting terrestrial signals in the isotopic data implies that factors other than local land use affect the relative incorporation of allochthonous subsidies into riverine food webs. Nevertheless, our results reveal how planting deciduous riparian trees along temperate headwaters as an adaptation to climate change can modify macroinvertebrate function, increase biomass and potentially enhance resilience by increasing basal resources where cover is extensive (>60 m riparian width). We advocate greater urgency in efforts to understand the ecosystem consequences of climate change adaptation to guide future actions. © 2015 John Wiley & Sons Ltd.

Guidelines for replacement of deficient bridges with low-water stream crossings in the rural Midwest.

DOT National Transportation Integrated Search

2017-02-01

This report provides guidance to public officials and engineers considering the replacement of a deficient or obsolete bridge with a low-water stream crossing (LWSC). An LWSC is a structure that is occasionally overtopped by floodwaters and is likely...

Innovative Remote Sensors for Streamflow Measurement

NASA Astrophysics Data System (ADS)

Gourley, J. J.; Fulton, J. W.; Daniel, W.

2016-12-01

The United States Geological Survey operates and maintains over 7000 streamgages across the United States., Conventional streamgages have several important limitations: annual maintenance cost of approximately $15k makes gaging smaller basins uneconomical, manual updating of stage-discharge rating curves is inefficient and can be hazardous to operators, and instruments in contact with the water are sometimes damaged or lost during flood events. A suite of new, non-contact sensors is proposed to address these limitations and add new, previously unmeasured variables. First, a commercially available radar system has been fielded in a very dynamic stream environment and successfully used to measure stage height and stream velocity at high temporal resolution, on the order of a few minutes. Second, a custom water-penetrating lidar has been developed and demonstrated to map 1-D bathymetry (cross-section) in clear streams. Combined with stage and velocity measurements from the radar, this will allow for computation of discharge using non-contact methods without the need to update and maintain an empirical rating curve. Once mature, these technologies promise to reduce cost and manual intervention, allow proliferation of measurements to smaller streams, and introduce previously unmeasured variables to the hydrological scientist's toolbox.

Measurement of discharge using tracers

USGS Publications Warehouse

Kilpatrick, Frederick A.; Cobb, Ernest D.

1984-01-01

The development of fluorescent dyes and fluorometers that can measure these dyes at very low concentrations has made dye-dilution methods practical for measuring discharge. These methods are particularly useful for determining discharge under certain flow conditions that are unfavorable for current meter measurements. These include small streams, canals, and pipes where:Turbulence is excessive for current meter measurement but conducive to good mixing.Moving rocks and debris are damaging to any instruments placed in the flow.Cross-sectional areas or velocities are indeterminant or changing.There are some unsteady flows such as exist with storm-runoff events on small streams.The flow is physically inaccessible or unsafe.From a practical standpoint, such measurements are limited primarily to small streams due to excessively long channel mixing lengths required of larger streams. Very good accuracy can be obtained provided:Adequate mixing length and time are allowed.Careful field and laboratory techniques are employed.Dye losses are not significant.This manual describes the slug-injection and constant-rate injection methods of performing tracer-dilution measurements. Emphasis is on the use of fluorescent dyes as tracers and the equipment, field methods, and Laboratory procedures for performing such measurements. The tracer-velocity method is also briefly discussed.

Streamflow and sediment-transport data, Colorado River and three tributaries in Grand Canyon, Arizona, 1983 and 1985-86

USGS Publications Warehouse

Garrett, W.B.; van de Vanter, E.K.; Graf, J.B.

1993-01-01

The U.S. Geological Survey collected streamflow and sediment-transport data at 5 streamflow-gaging stations on the Colorado River between Glen Canyon Dam and Lake Mead as a part of an interagency environmental study. The data were collected for about 6 mo in 1983 and about 4 mo in 1985-86; data also were collected at 3 sites on tributary streams in 1983. The data were used for development of unsteady flow-routing and sediment-transport models, sand-load rating curves, and evaluation of channel changes. For the 1983 sampling period, 1,076 composite cross-section suspended-sediment samples were analyzed; 809 of these samples were collected on the main stem of the Colorado River and 267 samples were from the tributaries. Bed-material samples were obtained at 1,988 verticals; 161 samples of material in transport near the bed (bedload) were collected to define the location of sand, gravel, and bed rock in the channel cross section; and 664 discharge measurements were made. For the 1985-86 sampling period, 765 composite cross-section suspended-sediment samples and 887 individual vertical samples from cross sections were analyzed. Bed-material samples were obtained at 531 verticals, 159 samples of bedload were collected, and 218 discharge measurements were made. All data are presented in tabular form. Some types of data also are presented in graphs to better show trends or variations. (USGS)

Airborne ROWS data report for the high resolution experiment, June 1993

NASA Technical Reports Server (NTRS)

Vandemark, D.; Hines, D.; Bailey, S.; Stewart, K.

1994-01-01

Airborne radar ocean wave spectrometer (ROWS) data collected during the Office of Naval Research's High Resolution Remote Sensing Experiment of June 1993 are presented. This data summary covers six flights made using NASA's T-39 aircraft over a region of the North Atlantic off the coast of North Carolina and includes multiple crossings of the gulf stream. The Ku-band ROWS was operated in a configuration which continuously switched between an altimeter and a spectrometer channel. Data derived from the two channels include altimeter radar cross section, altimeter-derived sea surface mean square slope and wind speed, and directional and nondirectional longwave spectra. Discussion is provided for several events of particular interest.

Guidelines for replacement of deficient bridges with low-water stream crossings in the rural Midwest : technical summary.

DOT National Transportation Integrated Search

2017-02-01

This report provides guidance to public officials and engineers considering the replacement of a deficient or obsolete bridge with a low-water stream crossing (LWSC). An LWSC is a structure that is occasionally overtopped by floodwaters and is likely...

Aeroacoustic measurements on a NACA 0012 applying the Coherent Particle Velocity method

NASA Astrophysics Data System (ADS)

Plogmann, B.; Würz, W.

2013-07-01

Aeroacoustic measurements on two NACA 0012 airfoil sections with different chord length and sharp trailing edge were conducted at the Laminar Wind Tunnel (LWT) of the University of Stuttgart. The LWT is a closed test section wind tunnel with a very low turbulence level and an acoustically optimized diffusor section allowing for high-quality aerodynamic as well as aeroacoustic measurements. Trailing edge noise measurements were performed using the Coherent Particle Velocity (CPV) method, which is based on a cross-spectral analysis of two hot-wire sensor signals placed on the suction and the pressure side of the airfoil trailing edge, respectively. At high angles of attack, the cross-spectral analysis of the two sensor signals used for the measurement of the trailing edge noise can be prone to a disturbing influence of hydrodynamic fluctuations. Hence, continuous shifts in the phasing of the cross-correlation are observed mainly for low sensor distances to the trailing edge. The quantitative evaluation of the trailing edge noise predominately in the low frequency range is, therefore, considerably disturbed. A new approach is proposed, which allows for the correction of the cross-correlation function based on the averaged single wire auto-spectrum. The results are compared to measurements with increased sensor distance and show good agreement. In the following, trailing edge noise measurements were performed on a NACA 0012 airfoil in a wide range of angles of attack ( α = 0°-8°) and free-stream velocities (u_{infty} = 30{-}70 {{m/s}}). The tripped flow cases exhibit a very good consistency for the scaling of the 1/3 octave spectra based on outer variables. Moreover, a common intersection point of the sound pressure level was observed for trailing edge noise spectra measured at constant free-stream velocity and different angles of attack. In cases without boundary layer tripping, the presence of an acoustic feedback loop was observed and linked to the presence of a laminar separation bubble on the pressure side in the vicinity of the trailing edge. Finally, a comparison of the aeroacoustic measurements based on the CPV method showed reasonably good agreement with published data obtained with both a microphone array and the Coherent Output Power method in open-test section facilities.

Estimated bankfull discharge for selected Michigan rivers and regional hydraulic geometry curves for estimating bankfull characteristics in southern Michigan rivers

USGS Publications Warehouse

Rachol, Cynthia M.; Boley-Morse, Kristine

2009-01-01

Regional hydraulic geometry curves are power-function equations that relate riffle dimensions and bankfull discharge to drainage-basin size. They are defined by data collected through surveys conducted at stable stream reaches and can be used to aid watershed managers, design engineers, and others involved in determination of the best course of action for an unstable stream. Hydraulic geometry curves provide a mechanism through which comparisons can be made between riffle dimensions collected at an unstable stream to those collected at stable streams within the same region. In 2005, a study was initiated to delineate regional hydraulic geometry curves for Michigan. After in-office review of 343 U.S. Geological Survey streamgaging stations and an extensive field reconnaissance effort, 44 stable reaches were selected for this study. Detailed surveys that included cross-sectional and longitudinal profiles and pebble counts were conducted at selected streamgages, which were distributed throughout Michigan. By use of survey data from riffle cross sections and water-surface slope, bankfull discharge was estimated and compared to flood-recurrence intervals using regional flood equations. This comparison shows that bankfull discharges in Michigan recur more frequently than every 2 years. Regional hydraulic geometry curves were developed rather than statewide curves owing to large differences in factors that control channel geometry across the State. However, after the data were subdivided according to ecoregions, it was determined that there were enough data to delineate regional hydraulic geometry curves only for the Southern Lower Michigan Ecoregion. For this ecoregion, geometry curve equations and their coefficients of determination are: Width = 8.19 x DA0.44; R2 = 0.69, Depth = 0.67 x DA0.27; R2 = 0.28, Area = 4.38 x DA0.74; R2 = 0.59, where DA is the drainage area and R2 is the coefficient of determination. By use of discharge estimates for the Southern Lower Michigan Ecoregion, a bankfull discharge curve was delineated. The corresponding equation and its coefficient of determination are: Discharge = 4.05 x DA0.95; R2 = 0.60

Field evaluation of the error arising from inadequate time averaging in the standard use of depth-integrating suspended-sediment samplers

USGS Publications Warehouse

Topping, David J.; Rubin, David M.; Wright, Scott A.; Melis, Theodore S.

2011-01-01

Several common methods for measuring suspended-sediment concentration in rivers in the United States use depth-integrating samplers to collect a velocity-weighted suspended-sediment sample in a subsample of a river cross section. Because depth-integrating samplers are always moving through the water column as they collect a sample, and can collect only a limited volume of water and suspended sediment, they collect only minimally time-averaged data. Four sources of error exist in the field use of these samplers: (1) bed contamination, (2) pressure-driven inrush, (3) inadequate sampling of the cross-stream spatial structure in suspended-sediment concentration, and (4) inadequate time averaging. The first two of these errors arise from misuse of suspended-sediment samplers, and the third has been the subject of previous study using data collected in the sand-bedded Middle Loup River in Nebraska. Of these four sources of error, the least understood source of error arises from the fact that depth-integrating samplers collect only minimally time-averaged data. To evaluate this fourth source of error, we collected suspended-sediment data between 1995 and 2007 at four sites on the Colorado River in Utah and Arizona, using a P-61 suspended-sediment sampler deployed in both point- and one-way depth-integrating modes, and D-96-A1 and D-77 bag-type depth-integrating suspended-sediment samplers. These data indicate that the minimal duration of time averaging during standard field operation of depth-integrating samplers leads to an error that is comparable in magnitude to that arising from inadequate sampling of the cross-stream spatial structure in suspended-sediment concentration. This random error arising from inadequate time averaging is positively correlated with grain size and does not largely depend on flow conditions or, for a given size class of suspended sediment, on elevation above the bed. Averaging over time scales >1 minute is the likely minimum duration required to result in substantial decreases in this error. During standard two-way depth integration, a depth-integrating suspended-sediment sampler collects a sample of the water-sediment mixture during two transits at each vertical in a cross section: one transit while moving from the water surface to the bed, and another transit while moving from the bed to the water surface. As the number of transits is doubled at an individual vertical, this error is reduced by ~30 percent in each size class of suspended sediment. For a given size class of suspended sediment, the error arising from inadequate sampling of the cross-stream spatial structure in suspended-sediment concentration depends only on the number of verticals collected, whereas the error arising from inadequate time averaging depends on both the number of verticals collected and the number of transits collected at each vertical. Summing these two errors in quadrature yields a total uncertainty in an equal-discharge-increment (EDI) or equal-width-increment (EWI) measurement of the time-averaged velocity-weighted suspended-sediment concentration in a river cross section (exclusive of any laboratory-processing errors). By virtue of how the number of verticals and transits influences the two individual errors within this total uncertainty, the error arising from inadequate time averaging slightly dominates that arising from inadequate sampling of the cross-stream spatial structure in suspended-sediment concentration. Adding verticals to an EDI or EWI measurement is slightly more effective in reducing the total uncertainty than adding transits only at each vertical, because a new vertical contributes both temporal and spatial information. However, because collection of depth-integrated samples at more transits at each vertical is generally easier and faster than at more verticals, addition of a combination of verticals and transits is likely a more practical approach to reducing the total uncertainty in most field situatio

Evaluating the accotink creek restoration project for improving water quality, in-stream habitat, and bank stability

USGS Publications Warehouse

Struck, S.D.; Selvakumar, A.; Hyer, K.; O'Connor, T.

2007-01-01

Increased urbanization results in a larger percentage of connected impervious areas and can contribute large quantities of stormwater runoff and significant quantities of debris and pollutants (e.g., litter, oils, microorganisms, sediments, nutrients, organic matter, and heavy metals) to receiving waters. To improve water quality in urban and suburban areas, watershed managers often incorporate best management practices (BMPs) to reduce the quantity of runoff as well as to minimize pollutants and other stressors contained in stormwater runoff. It is well known that land-use practices directly impact urban streams. Stream flows in urbanized watersheds increase in magnitude as a function of impervious area and can result in degradation of the natural stream channel morphology affecting the physical, chemical, and biological integrity of the stream. Stream bank erosion, which also increases with increased stream flows, can lead to bank instability, property loss, infrastructure damage, and increased sediment loading to the stream. Increased sediment loads may lead to water quality degradation downstream and have negative impacts on fish, benthic invertebrates, and other aquatic life. Accotink Creek is in the greater Chesapeake Bay and Potomac watersheds, which have strict sediment criteria. The USEPA (United States Environmental Protection Agency) and USGS (United States Geological Survey) are investigating the effectiveness of stream restoration techniques as a BMP to decrease sediment load and improve bank stability, biological integrity, and in-stream water quality in an impaired urban watershed in Fairfax, Virginia. This multi-year project continuously monitors turbidity, specific conductance, pH, and water temperature, as well as biological and chemical water quality parameters. In addition, physical parameters (e.g., pebble counts, longitudinal and cross sectional stream surveys) were measured to assess geomorphic changes associated with the restoration. Data from the pre-construction and initial post-construction phases are presented in this report. ?? 2007 ASCE.

Construction and test of flexible walls for the throat of the ILR high-speed wind tunnel

NASA Technical Reports Server (NTRS)

Igeta, Y.

1983-01-01

Aerodynamic tests in wind tunnels are jeopardized by the lateral limitations of the throat. This influence expands with increasing size of the model in proportion to the cross-section of the throat. Wall interference of this type can be avoided by giving the wall the form of a stream surface that would be identical to the one observed during free flight. To solve this problem, flexible walls that can adapt to every contour of surface flow are needed.

Design and calibration of the mixing layer and wind tunnel

NASA Technical Reports Server (NTRS)

Bell, James H.; Mehta, Rabindra D.

1989-01-01

A detailed account of the design, assembly and calibration of a wind tunnel specifically designed for free-shear layer research is contained. The construction of this new facility was motivated by a strong interest in the study of plane mixing layers with varying initial and operating conditions. The Mixing Layer Wind tunnel is located in the Fluid Mechanics Laboratory at NASA Ames Research Center. The tunnel consists of two separate legs which are driven independently by centrifugal blowers connected to variable speed motors. The blower/motor combinations are sized such that one is smaller than the other, giving maximum flow speeds of about 20 and 40 m/s, respectively. The blower speeds can either be set manually or via the Microvax II computer. The two streams are allowed to merge in the test section at the sharp trailing edge of a slowly tapering splitter plate. The test section is 36 cm in the cross-stream direction, 91 cm in the spanwise direction and 366 cm in length. One test section side-wall is slotted for probe access and adjustable so that the streamwise pressure gradient may be controlled. The wind tunnel is also equipped with a computer controlled, three-dimensional traversing system which is used to investigate the flow fields with pressure and hot-wire instrumentation. The wind tunnel calibration results show that the mean flow in the test section is uniform to within plus or minus 0.25 pct and the flow angularity is less than 0.25 deg. The total streamwise free-stream turbulence intensity level is approximately 0.15 pct. Currently the wind tunnel is being used in experiments designed to study the three-dimensional structure of plane mixing layers and wakes.

Quantifying stream channel sediment contributions for the Paradise Creek Watershed in northern Idaho

NASA Astrophysics Data System (ADS)

Rittenburg, R.; Squires, A.; Boll, J.; Brooks, E. S.

2012-12-01

Excess sediment from agricultural areas has been a major source of impairment for water bodies around the world, resulting in the implementation of mitigation measures across landscapes. Watershed scale reductions often target upland erosion as key non-point sources for sediment loading. Stream channel dynamics, however, also play a contributing role in sediment loading in the form of legacy sediments, channel erosion and deposition, and buffering during storm events. Little is known about in-stream contributions, a potentially important consideration for Total Maximum Daily Loads (TMDLs). The objective of this study is to identify where and when sediment is delivered to the stream and the spatial and temporal stream channel contributions to the overall watershed scale sediment load. The study area is the Paradise Creek Watershed in northern Idaho. We modeled sediment yield to the channel system using the Water Erosion Prediction Project (WEPP) model, and subsequent channel erosion and deposition using CONCEPTs. Field observations of cross-sections along the channel system over a 5-year period were collected to verify model simulations and to test the hypothesis that the watershed load was made up predominantly of legacy sediments. Our modeling study shows that stream channels contributed to 50% of the total annual sediment load for the basin, with a 19 year time lag between sediments entering the stream to leaving the watershed outlet. Observations from long-term data in the watershed will be presented to indicate if the main source of the sediment is from either rural and urban non-point sources or the channel system.

Spatial Distribution of Bed Particles in Natural Boulder-Bed Streams

NASA Astrophysics Data System (ADS)

Clancy, K. F.; Prestegaard, K. L.

2001-12-01

The Wolman pebble count is used to obtain the size distribution of bed particles in natural streams. Statistics such as median particle size (D50) are used in resistance calculations. Additional information such as bed particle heterogeneity may also be obtained from the particle distribution, which is used to predict sediment transport rates (Hey, 1979), (Ferguson, Prestegaard, Ashworth, 1989). Boulder-bed streams have an extreme range of particles in the particle size distribution ranging from sand size particles to particles larger than 0.5-m. A study of a natural boulder-bed reach demonstrated that the spatial distribution of the particles is a significant factor in predicting sediment transport and stream bed and bank stability. Further experiments were performed to test the limits of the spatial distribution's effect on sediment transport. Three stream reaches 40-m in length were selected with similar hydrologic characteristics and spatial distributions but varying average size particles. We used a grid 0.5 by 0.5-m and measured four particles within each grid cell. Digital photographs of the streambed were taken in each grid cell. The photographs were examined using image analysis software to obtain particle size and position of the largest particles (D84) within the reach's particle distribution. Cross section, topography and stream depth were surveyed. Velocity and velocity profiles were measured and recorded. With these data and additional surveys of bankfull floods, we tested the significance of the spatial distributions as average particle size decreases. The spatial distribution of streambed particles may provide information about stream valley formation, bank stability, sediment transport, and the growth rate of riparian vegetation.

Analysis and classification of bedload transport events with variable process characteristics

NASA Astrophysics Data System (ADS)

Kreisler, Andrea; Moser, Markus; Aigner, Johann; Rindler, Rolf; Tritthart, Michael; Habersack, Helmut

2017-08-01

Knowledge about the magnitude of bedload fluxes at given hydraulic conditions in natural streams is essential for improved process understanding, for the application, calibration and validation of bedload transport formulas, and for numerical sediment transport models. Nonetheless, extensive field measurements of bedload transport are challenging and therefore data from such efforts are rare. Bedload transport has been measured comprehensively at the downstream section of the Urslau torrent in Salzburg, Austria, since 2011. We used an integrative monitoring system that combines direct (mobile basket sampler, slot sampler) and indirect measuring devices (geophone plates). Continuous information about the intensity and distribution of bedload transport within the channel cross-section is available in high spatial and temporal resolution. Seven geophone plates at a stream width of 8 m are part of a measurement system that delivers data in 1-min intervals. These geophone data are calibrated using results of direct bedload measurements, providing an opportunity to calculate bedload rates and bedload yields in selected time periods. Continuous data on the bedload transport process over three years enabled assessing several bedload transport events. The investigation of bedload transport rate/discharge relationships reveals order-of-magnitude changes. For individual events, we observed shifts in the data, reflecting different bedload rates at comparable hydraulic conditions. This study reveals that variable sediment supply conditions affect the prevailing bedload transport rates at the Urslau stream. Calculating the bedload transport efficiency enables comparing bedload transport events that exhibit similar process characteristics. Finally, we provide a conceptual model of bedload transport process types as a function of bedload transport efficiency and dimensionless stream power.

Dynamic Change of Water Quality in Hyporheic Zone at Water Curtain Cultivation Area, Cheongju, Korea

NASA Astrophysics Data System (ADS)

Moon, S. H.; Kim, Y.

2015-12-01

There has been recently growing numbers of facilities for water curtain cultivation of strawberry and lettuce in Korea. These areas are nearly all located in the fluvial deposits near streams which can replenish water resources into exhausted groundwater aquifers during peak season. The purpose of this study is on groundwater chemistry and the change in physical and chemical properties due to stream-groundwater exchange or mixing in the representative agricultural area among the Jurassic granitic terrain of Korea. In the study area, groundwater level continuously decreased from November through March due to intensive use of groundwater, which forced stream water into aquifer. After March, groundwater level was gradually recovered to the original state. To evaluate the extent and its variations of stream water mixing into aquifer, field parameters including T, pH, EC and DO values, concentrations of major ions and oxygen and hydrogen stable isotopic ratios were used. Field measurements and water sample collections were performed several times from 2012 to 2015 mainly during peak time of groundwater use. To compare the temporal variations and areal differences, 21 wells from four cross sections perpendicular to stream line were used. While water temperature, EC values and concentrations of Ca, Mg, Si, HCO3 showed roughly gradual increase from stream line to 150 m distance, pH and DO values showed reverse phenomenon. This can be used to evaluate the extent and limit of stream water introduction into aquifer. However, individual wells showed yearly variations in those parameters and this dynamic and unstable feature indicates that mixing intensity of stream water over groundwater in this hyporheic zone varied year by year according to amounts of groundwater use and decrease of groundwater level.

Equations for estimating bankfull channel geometry and discharge for streams in Massachusetts

USGS Publications Warehouse

Bent, Gardner C.; Waite, Andrew M.

2013-01-01

Regression equations were developed for estimating bankfull geometry—width, mean depth, cross-sectional area—and discharge for streams in Massachusetts. The equations provide water-resource and conservation managers with methods for estimating bankfull characteristics at specific stream sites in Massachusetts. This information can be used for the adminstration of the Commonwealth of Massachusetts Rivers Protection Act of 1996, which establishes a protected riverfront area extending from the mean annual high-water line corresponding to the elevation of bankfull discharge along each side of a perennial stream. Additionally, information on bankfull channel geometry and discharge are important to Federal, State, and local government agencies and private organizations involved in stream assessment and restoration projects. Regression equations are based on data from stream surveys at 33 sites (32 streamgages and 1 crest-stage gage operated by the U.S. Geological Survey) in and near Massachusetts. Drainage areas of the 33 sites ranged from 0.60 to 329 square miles (mi2). At 27 of the 33 sites, field data were collected and analyses were done to determine bankfull channel geometry and discharge as part of the present study. For 6 of the 33 sites, data on bankfull channel geometry and discharge were compiled from other studies done by the U.S. Geological Survey, Natural Resources Conservation Service of the U.S. Department of Agriculture, and the Vermont Department of Environmental Conservation. Similar techniques were used for field data collection and analysis for bankfull channel geometry and discharge at all 33 sites. Recurrence intervals of the bankfull discharge, which represent the frequency with which a stream fills its channel, averaged 1.53 years (median value 1.34 years) at the 33 sites. Simple regression equations were developed for bankfull width, mean depth, cross-sectional area, and discharge using drainage area, which is the most significant explanatory variable in estimating these bankfull characteristics. The use of drainage area as an explanatory variable is also the most commonly published method for estimating these bankfull characteristics. Regional curves (graphic plots) of bankfull channel geometry and discharge by drainage area are presented. The regional curves are based on the simple regression equations and can be used to estimate bankfull characteristics from drainage area. Multiple regression analysis, which includes basin characteristics in addition to drainage area, also was used to develop equations. Variability in bankfull width, mean depth, cross-sectional area, and discharge was more fully explained by the multiple regression equations that include mean-basin slope and drainage area than was explained by equations based on drainage area alone. The Massachusetts regional curves and equations developed in this study are similar, in terms of values of slopes and intercepts, to those developed for other parts of the northeastern United States. Limitations associated with site selection and development of the equations resulted in some constraints for the application of equations and regional curves presented in this report. The curves and equations are applicable to stream sites that have (1) less than about 25 percent of their drainage basin area occupied by urban land use (commercial, industrial, transportation, and high-density residential), (2) little to no streamflow regulation, especially from flood-control structures, (3) drainage basin areas greater than 0.60 mi2 and less than 329 mi2, and (4) a mean basin slope greater than 2.2 percent and less than 23.9 percent. The equations may not be applicable where streams flow through extensive wetlands. The equations also may not apply in areas of Cape Cod and the Islands and the area of southeastern Massachusetts close to Cape Cod with extensive areas of coarse-grained glacial deposits where none of the study sites are located. Regardless of the setting, the regression equations are not intended for use as the sole method of estimating bankfull characteristics; however, they may supplement field identification of the bankfull channel when used in conjunction with field verified bankfull indicators, flood-frequency analysis, or other supporting evidence.

The Function of Consciousness in Multisensory Integration

ERIC Educational Resources Information Center

Palmer, Terry D.; Ramsey, Ashley K.

2012-01-01

The function of consciousness was explored in two contexts of audio-visual speech, cross-modal visual attention guidance and McGurk cross-modal integration. Experiments 1, 2, and 3 utilized a novel cueing paradigm in which two different flash suppressed lip-streams cooccured with speech sounds matching one of these streams. A visual target was…

Measurements and modeling of flow structure in the wake of a low profile wishbone vortex generator

NASA Technical Reports Server (NTRS)

Wendt, B. J.; Hingst, W. R.

1994-01-01

The results of an experimental examination of the vortex structures shed from a low profile 'wishbone' generator are presented. The vortex generator height relative to the turbulent boundary layer was varied by testing two differently sized models. Measurements of the mean three-dimensional velocity field were conducted in cross-stream planes downstream of the vortex generators. In all cases, a counter-rotating vortex pair was observed. Individual vortices were characterized by three descriptors derived from the velocity data; circulation, peak vorticity, and cross-stream location of peak vorticity. Measurements in the cross plane at two axial locations behind the smaller wishbone characterize the downstream development of the vortex pairs. A single region of stream wise velocity deficit is shared by both vortex cores. This is in contrast to conventional generators, where each core coincides with a region of velocity deficit. The measured cross-stream velocities for each case are compared to an Oseen model with matching descriptors. The best comparison occurs with the data from the larger wishbone.

Spatial Patterns of Road-Induced Backwater Sediment Storage Across A Rural to Urban Gradient

NASA Astrophysics Data System (ADS)

Copeland, M.; Bain, D.

2017-12-01

Road networks dominate many landscapes and often interact with stream networks to alter basin sediment dynamics. Currently, conceptual models of catchment-scale sediment fluxes remain at a coarse scale (i.e., the entire catchment) and are unable to resolve important human-driven sediment storage processes. The spatio-temporal complexity of the interactions between road networks and streams has made it challenging to infer the fine-scale impacts of road crossings on fluvial systems. Here, road crossings in multiple drainage networks and the associated backwater sediment accumulations are examined along a rural to urban gradient around Pittsburgh, PA. Preliminary results indicate that upstream drainage area, channel slope, and human activities control stream crossing type and therefore drive associated sediment accumulation, particularly in urban headwater channels. The data indicate that the combination of land use intensity and infrastructure age influences the volume of sediment trapped in road-induced backwaters. Clarification of the coupled human, road-building, and natural stream adjustments will allow for more effective treatments of fluvial impacts, such as the "urban stream syndrome."

Rapid Assessment of Logging-Associated Sediment-Delivery Pathways in an Intensively-Managed Forested Watershed in the Southern Cascades, Northern California

NASA Astrophysics Data System (ADS)

Coe, D. B.; Wopat, M. A.; Lindsay, D.; Stanish, S.; Boone, M.; Beck, B.; Wyman, A.; Bull, J.

2012-12-01

The potential for water-quality impacts in intensively-managed forested watersheds depends partly upon the frequency of overland flow paths linking logging-related hillslope sediment sources to the channel network, as well as the volume of sediment delivered along these flow paths. In response to public concerns over perceived water-quality impacts from clearcut timber harvesting, the Battle Creek Task Force, composed of subject-matter experts from 4 different state agencies, performed a rapid assessment for visible evidence of sediment delivery pathways from multiple logging-associated features in the upper Battle Creek watershed - an area underlain predominantly by Holocene- and Late Pleistocene-aged volcanic rock types, with highly permeable soils, and relatively few streams. Logging-associated features were selected for assessment based on erosion potential and proximity to stream channels. Identified sediment-delivery pathways were then characterized by dominant erosion process and the relative magnitude of sediment delivery (i.e., low, moderate, and high) was estimated. Approximately 26 km of stream buffers adjacent to 55 clearcut harvest units were assessed, and the single detected instance of sediment delivery was found to be of low magnitude and the result of illegal encroachment by logging equipment into a 5-m wide stream-adjacent equipment-limitation zone. The proportion of sampled sites delivering sediment was found to be highest for tractor-stream crossings, followed by road-stream crossings, stream-adjacent road segments, stream-adjacent landings, and clearcut harvest units, respectively. All 5 tractor-stream crossings delivered sediment, but were generally delivering a low magnitude of sediment derived from sheetwash and rilling. Road-stream crossings (n=39) and stream-adjacent road segments (n=24) delivered observable sediment 69 and 67 percent of the time, respectively. The highest magnitudes of sediment delivery from roads were associated with substandard design or maintenance practices (e.g., poor road drainage) and/or poor location (e.g., roads less than 15 m from a stream), but the magnitude of sediment delivery was generally low or unobservable where Best Management Practices (BMPs) had been implemented. Conceptually, water-quality impacts are limited by the low density of streams in the watershed, relatively low hillslope gradients, relatively high permeability of the soils, and the implementation of BMPs. Assessment results suggest that direct water-quality impacts from overland flow paths in these types of watersheds are best minimized by disconnecting flow paths linking roads to streams, and by implementing BMPs.

Formation and Control of Fluidic Species

NASA Technical Reports Server (NTRS)

Link, Darren Roy (Inventor); Marquez-Sanchez, Manuel (Inventor); Cheng, Zhengdong (Inventor); Weitz, David A. (Inventor)

2015-01-01

This invention generally relates to systems and methods for the formation and/or control of fluidic species, and articles produced by such systems and methods. In some cases, the invention involves unique fluid channels, systems, controls, and/or restrictions, and combinations thereof. In certain embodiments, the invention allows fluidic streams (which can be continuous or discontinuous, i.e., droplets) to be formed and/or combined, at a variety of scales, including microfluidic scales. In one set of embodiments, a fluidic stream may be produced from a channel, where a cross-sectional dimension of the fluidic stream is smaller than that of the channel, for example, through the use of structural elements, other fluids, and/or applied external fields, etc. In some cases, a Taylor cone may be produced. In another set of embodiments, a fluidic stream may be manipulated in some fashion, for example, to create tubes (which may be hollow or solid), droplets, nested tubes or droplets, arrays of tubes or droplets, meshes of tubes, etc. In some cases, droplets produced using certain embodiments of the invention may be charged or substantially charged, which may allow their further manipulation, for instance, using applied external fields. Non-limiting examples of such manipulations include producing charged droplets, coalescing droplets (especially at the microscale), synchronizing droplet formation, aligning molecules within the droplet, etc. In some cases, the droplets and/or the fluidic streams may include colloids, cells, therapeutic agents, and the like.

Relation between Working Memory Capacity and Auditory Stream Segregation in Children with Auditory Processing Disorder.

PubMed

Lotfi, Yones; Mehrkian, Saiedeh; Moossavi, Abdollah; Zadeh, Soghrat Faghih; Sadjedi, Hamed

2016-03-01

This study assessed the relationship between working memory capacity and auditory stream segregation by using the concurrent minimum audible angle in children with a diagnosed auditory processing disorder (APD). The participants in this cross-sectional, comparative study were 20 typically developing children and 15 children with a diagnosed APD (age, 9-11 years) according to the subtests of multiple-processing auditory assessment. Auditory stream segregation was investigated using the concurrent minimum audible angle. Working memory capacity was evaluated using the non-word repetition and forward and backward digit span tasks. Nonparametric statistics were utilized to compare the between-group differences. The Pearson correlation was employed to measure the degree of association between working memory capacity and the localization tests between the 2 groups. The group with APD had significantly lower scores than did the typically developing subjects in auditory stream segregation and working memory capacity. There were significant negative correlations between working memory capacity and the concurrent minimum audible angle in the most frontal reference location (0° azimuth) and lower negative correlations in the most lateral reference location (60° azimuth) in the children with APD. The study revealed a relationship between working memory capacity and auditory stream segregation in children with APD. The research suggests that lower working memory capacity in children with APD may be the possible cause of the inability to segregate and group incoming information.

In-channel Restoration Structures and the Implications on Hyporheic Exchange: a Laboratory Experiment

NASA Astrophysics Data System (ADS)

Han, B.; Chu, H. H.; Endreny, T. A.

2014-12-01

In-channel structures, i.e. cross-vanes and J-hooks, are commonly installed in river restoration projects to modify the streambed morphology and stream water surface profile, and are known to change hyporhiec exchange flux and habitats for riverine animals. However, few studies have continuous and accurate pre- and post-treatment data to evaluate the impact of these structures on channel hydraulic gradients and morphology. To quantify the effects of in-channel structures, we developed a scaled physical model of a meandering stream with a cross-vane and 6 J-hooks on a mobile-bed river table. Close-range photogrammetry technique was applied to obtain 3-D water and ground surface profiles with sub-millimeter vertical accuracy and horizontal resolution. The experiment was compared with a control experiment without structures while maintaining the same initial conditions of river bed, floodplain and stream flow. Results indicated that the cross-vane caused an average local head loss that represented 16% of the total stream reach head loss, and a 74% increase in channel load in the entire stream reach. Most J-hooks can create stepwise patterns in stream longitudinal profile, and cross-vane can create even more significant ones. Hydraulic gradients across the intra-meander zone also increased with in-channel structures, i.e. from 2.5% to 3.5% at the meander neck. Scour pools developed downstream of the cross-vane, and mostly around the 4 meander apex J-hooks at their hooked tip. Backwater caused by the cross-vane steepened the local water table profile by an additional 4.2%, and was the primary driver of statistically significant hydraulic gradient increase. Reach scale water and streambed surface profiles from our study provided detailed data to improve the understanding of in-channel structure effects, and may serve as reliable data source in computational modeling of hyporheic exchange.

Comparison between Measured and Calculated Sediment Transport Rates in North Fork Caspar Creek, California

NASA Astrophysics Data System (ADS)

Kim, T. W.; Yarnell, S. M.; Yager, E.; Leidman, S. Z.

2015-12-01

Caspar Creek is a gravel-bedded stream located in the Jackson Demonstration State Forest in the coast range of California. The Caspar Creek Experimental Watershed has been actively monitored and studied by the Pacific Southwest Research Station and California Department of Forestry and Fire Protection for over five decades. Although total annual sediment yield has been monitored through time, sediment transport during individual storm events is less certain. At a study site on North Fork Caspar Creek, cross-section averaged sediment flux was collected throughout two storm events in December 2014 and February 2015 to determine if two commonly used sediment transport equations—Meyer-Peter-Müller and Wilcock—approximated observed bedload transport. Cross-section averaged bedload samples were collected approximately every hour during each storm event using a Helley-Smith bedload sampler. Five-minute composite samples were collected at five equally spaced locations along a cross-section and then sieved to half-phi sizes to determine the grain size distribution. The measured sediment flux values varied widely throughout the storm hydrographs and were consistently less than two orders of magnitude in value in comparison to the calculated values. Armored bed conditions, changing hydraulic conditions during each storm and variable sediment supply may have contributed to the observed differences.

2. VIEW OF THE LOCATION WHERE A STREAM CROSSING WILL ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. VIEW OF THE LOCATION WHERE A STREAM CROSSING WILL BE CONSTRUCTED FOR TRUCK HAULING PURPOSES DURING THE SALE AND WHERE THE AREA WILL BE RETURNED TO ITS NATURAL STATE AFTER HAULING IS COMPLETED. LOCATED IMMEDIATELY SOUTH OF HELIPAD #13. FACING NORTH 5 WEST (355ø). - Genoa Peak Road, Spur, Glenbrook, Douglas County, NV

Erosion at decommissioned road-stream crossings: case studies from three northern California watersheds

Treesearch

Sam A. Flanagan; David Fuller; Leonard Job; Sam Morrison

2012-01-01

Post-treatment erosion was observed for 41 decommissioned road stream crossings in three northern California watersheds. Sites were purposefully selected in order to characterize the nature and range of post-treatment erosional responses. Sites with the highest visible erosion were selected in order to better understand the dominant process and incorporate any...

Effect of electron thermal anisotropy on the kinetic cross-field streaming instability

NASA Technical Reports Server (NTRS)

Tsai, S. T.; Tanaka, M.; Gaffey, J. D., Jr.; Wu, C. S.; Da Jornada, E. H.; Ziebell, L. F.

1984-01-01

The investigation of the kinetic cross-field streaming instability, motivated by the research of collisionless shock waves and previously studied by Wu et al. (1983), is discussed more fully. Since in the ramp region of a quasi-perpendicular shock electrons can be preferentially heated in the direction transverse to the ambient magnetic field, it is both desirable and necessary to include the effect of the thermal anisotropy on the instability associated with a shock. It is found that Te-perpendicular greater than Te-parallel can significantly enhance the peak growth rate of the cross-field streaming instability when the electron beta is sufficiently high. Furthermore, the present analysis also improves the analytical and numerical solutions previously obtained.

Oblique impact of dense granular sheets

NASA Astrophysics Data System (ADS)

Ellowitz, Jake; Guttenberg, Nicholas; Jaeger, Heinrich M.; Nagel, Sidney R.; Zhang, Wendy W.

2013-11-01

Motivated by experiments showing impacts of granular jets with non-circular cross sections produce thin ejecta sheets with anisotropic shapes, we study what happens when two sheets containing densely packed, rigid grains traveling at the same speed collide asymmetrically. Discrete particle simulations and a continuum frictional fluid model yield the same steady-state solution of two exit streams emerging from incident streams. When the incident angle Δθ is less than Δθc =120° +/-10° , the exit streams' angles differ from that measured in water sheet experiments. Below Δθc , the exit angles from granular and water sheet impacts agree. This correspondence is surprising because 2D Euler jet impact, the idealization relevant for both situations, is ill posed: a generic Δθ value permits a continuous family of solutions. Our finding that granular and water sheet impacts evolve into the same member of the solution family suggests previous proposals that perturbations such as viscous drag, surface tension or air entrapment select the actual outcome are not correct. Currently at Department of Physics, University of Oregon, Eugene, OR 97403.

Selective evaporation of focusing fluid in two-fluid hydrodynamic print head.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keicher, David M.; Cook, Adam W.

The work performed in this project has demonstrated the feasibility to use hydrodynamic focusing of two fluid steams to create a novel micro printing technology for electronics and other high performance applications. Initial efforts focused solely on selective evaporation of the sheath fluid from print stream provided insight in developing a unique print head geometry allowing excess sheath fluid to be separated from the print flow stream for recycling/reuse. Fluid flow models suggest that more than 81 percent of the sheath fluid can be removed without affecting the print stream. Further development and optimization is required to demonstrate this capabilitymore » in operation. Print results using two-fluid hydrodynamic focusing yielded a 30 micrometers wide by 0.5 micrometers tall line that suggests that the cross-section of the printed feature from the print head was approximately 2 micrometers in diameter. Printing results also demonstrated that complete removal of the sheath fluid is not necessary for all material systems. The two-fluid printing technology could enable printing of insulated conductors and clad optical interconnects. Further development of this concept should be pursued.« less

The LISST-SL streamlined isokinetic suspended-sediment profiler

USGS Publications Warehouse

Gray, John R.; Agrawal, Yogesh C.; Pottsmith, H. Charles

2004-01-01

The new manually deployed Laser In Situ Scattering Transmissometer-StreamLined profiler (LISST-SL) represents a major technological advance for suspended-sediment measurements in rivers. The LISST-SL is being designed to provide real-time data on sediment concentrations and particle-size distributions. A pressure sensor and current meter provide real-time depth and ambient velocity data, respectively. The velocity data are also used to control pumpage across an internal laser so that the intake velocity is constantly adjusted to match the ambient stream velocity. Such isokinetic withdrawal is necessary for obtaining representative sedimentary measurements in streamflow, and ensures compliance with established practices. The velocity and sediment-concentration data are used to compute fluxes for up to 32 particle-size classes at points, verticals, or in the entire stream cross section. All data are stored internally, as well as transmitted via a 2-wire conductor to the operator using a specially developed communication protocol. The LISST-SL's performance will be measured and compared to published sedimentological accuracy criteria, and a performance summary will be placed on-line.

Stream channel degradation and aggradation : analysis of impacts to highway crossings.

DOT National Transportation Integrated Search

1981-03-01

"Aggradation and degradation are long-term changes in stream channel elevation. The effects of gradation changes are not the same as local scour or erosion because they extend greater distances along the stream-bed. Degradation is a more common probl...

Space, energy and anisotropy effects on effective cross sections and diffusion coefficients in the resonance region

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meftah, B.

1982-01-01

Present methods used in reactor analysis do not include adequately the effect of anisotropic scattering in the calculation of resonance effective cross sections. Also the assumption that the streaming term ..cap omega...del Phi is conserved when the total, absorption and transfer cross sections are conserved, is bad because the leakage from a heterogeneous cell will not be conserved and is strongly anisotropic. A third major consideration is the coupling between different regions in a multiregion reactor; currently this effect is being completely ignored. To assess the magnitude of these effects, a code based on integral transport formalism with linear anisotropicmore » scattering was developed. Also, a more adequate formulation of the diffusion coefficient in a heterogeneous cell was derived. Two reactors, one fast, ZPR-6/5, and one thermal, TRX-3, were selected for the study. The study showed that, in general, the inclusion of linear scattering anisotropy increases the cell effective capture cross section of U-238. The increase was up to 2% in TRX-3 and 0.5% in ZPR-6/5. The effect on the multiplication factor was -0.003% ..delta..k/k for ZPR-6/5 and -0.05% ..delta..k/k for TRX-3. For the case of the diffusion coefficient, the combined effect of heterogeneity and linear anisotropy gave an increase of up to 29% in the parallel diffusion coefficient of TRX-3 and 5% in the parallel diffusion coefficient of ZPR-6/5. In contrast, the change in the perpendicular diffusion coefficient did not exceed 2% in both systems.« less

Comparison of the Experimental and Theoretical Distribution of Lift on a Slender Inclined Body of Revolution at M = 2

NASA Technical Reports Server (NTRS)

Perkins, Edward W; Kuehn, Donald M

1953-01-01

Pressure distributions and force characteristics have been determined for a body of revolution consisting of a fineness ratio 5.75, circular-arc, ogival nose tangent to a cylindrical afterbody for an angle-of-attack range of 0 degrees to 35.5 degrees. The free-stream Mach number was 1.98 and the free-stream Reynolds number was approximately 0.5 x 10 sup 6, based on body diameter. Comparison of the theoretical and experimental pressure distributions shows that for zero lift, either slender-body theory or higher-order theories yield results which are in good agreement with experiment. For the lifting case, good agreement with theory is found only for low angles of attack and for the region in which the body cross-sectional area is increasing in the downstream direction. Because of the effects of cross-flow separation and the effects of compressibility due to the high cross-flow Mach numbers at large angles of attack, the experimental pressure distributions differ from those predicted by potential theory. Although the flow about the inclined body was, in general, similar to that assumed as the basis for Allen's method of estimating the forces resulting from viscous effects (NACA RM A91I26), the distribution of the forces was significantly different from that assumed. Nevertheless, the lift and pitching-moment characteristics were in fair agreement with the estimated value.

Low latency adaptive streaming of HD H.264 video over 802.11 wireless networks with cross-layer feedback

NASA Astrophysics Data System (ADS)

Patti, Andrew; Tan, Wai-tian; Shen, Bo

2007-09-01

Streaming video in consumer homes over wireless IEEE 802.11 networks is becoming commonplace. Wireless 802.11 networks pose unique difficulties for streaming high definition (HD), low latency video due to their error-prone physical layer and media access procedures which were not designed for real-time traffic. HD video streaming, even with sophisticated H.264 encoding, is particularly challenging due to the large number of packet fragments per slice. Cross-layer design strategies have been proposed to address the issues of video streaming over 802.11. These designs increase streaming robustness by imposing some degree of monitoring and control over 802.11 parameters from application level, or by making the 802.11 layer media-aware. Important contributions are made, but none of the existing approaches directly take the 802.11 queuing into account. In this paper we take a different approach and propose a cross-layer design allowing direct, expedient control over the wireless packet queue, while obtaining timely feedback on transmission status for each packet in a media flow. This method can be fully implemented on a media sender with no explicit support or changes required to the media client. We assume that due to congestion or deteriorating signal-to-noise levels, the available throughput may drop substantially for extended periods of time, and thus propose video source adaptation methods that allow matching the bit-rate to available throughput. A particular H.264 slice encoding is presented to enable seamless stream switching between streams at multiple bit-rates, and we explore using new computationally efficient transcoding methods when only a high bit-rate stream is available.

National Dam Safety Program. Tomahawk Lake Dam (Inventory Number N.Y. 618), Lower Hudson River Basin, Orange County, New York. Phase I Inspection Report,

DTIC Science & Technology

1981-08-14

Guidelines for Safety Inspection of Dams. d. Hazard Classification - Cherry Hill Road crosses the channel 1600 feet downstream from the dam and Tuthill...Road crosses the channel 1.5 miles below the dam. A home is located within 5 feet of the stream elevation, about 10 feet from the stream, and...below the dam. Cherry Hill Road crosses the channel 1600 feet downstream of the dam and Tuthill Road crosses the channel 1.5 miles below the dam. A home

Occurrence of riverine wetlands on floodplains along a climatic gradient

USGS Publications Warehouse

Kroes, D.E.; Brinson, M.M.

2004-01-01

The relation between the occurrence of riverine wetlands in floodplains along a humid to semi-arid climatic continuum was studied in two regions. The first included 36 mid-reach streams from Colorado to Iowa, USA, a region with a broad range of PET ratios (potential evapotranspiration/precipitation) from 0.70 to 1.75. The second region included 16 headwater streams in eastern North Carolina with PET ratios ranging from 0.67 to 0.83. Wetland boundaries were identified in the field along transects perpendicular to the floodplain. The width of jurisdictional wetlands was compared with flood-prone width (FPW) and expressed as a percent. An increase in PET ratio corresponded to an exponential decrease in the percentage of the FPW that is wetland. Soil texture, duration of overbank flow, and stream order did not correlate with percentage of FPW that was wetland. Streams with a PET ratio greater than 0.98 did not have wetlands associated with them. Greater channel cross-sectional areas correlated positively with greater wetland widths in both study regions. Overbank flow did not appear to contribute to wetland prevalence. Supplemental ground-water sources, however, as indicated by greater base flows, could not be ruled out as sources contributing to wetland occurrence. ?? 2004, The Society of Wetland Scientists.

Measurement of discharge using tracers

USGS Publications Warehouse

Kilpatrick, F.A.; Cobb, Ernest D.

1985-01-01

The development of fluorescent dyes and fluorometers that can measure these dyes at very low concentrations has made dye-dilution methods practical for measuring discharge. These methods are particularly useful for determining discharge under certain flow conditions that are unfavorable for current meter measurements. These include small streams, canals, and pipes where 1. Turbulence is excessive for current-meter measurement but conducive to good mixing. 2. Moving rocks and debris may damage instruments placed in the flow. 3. Cross-sectional areas or velocities are indeterminate or changing. 4. The flow is unsteady, such as the flow that exists with storm-runoff events on small streams and urban storm-sewer systems. 5. The flow is physically inaccessible or unsafe. From a practical standpoint, such methods are limited primarily to small streams, because of the excessively long channel-mixing lengths required for larger streams. Very good accuracy can be obtained provided that 1. Adequate mixing length and time are allowed. 2. Careful field and laboratory techniques are used. 3. Dye losses are not significant. This manual describes the slug-injection and constant-rate injection methods of performing tracer-dilution measurements. Emphasis is on the use of fluorescent dyes as tracers and the equipment, field methods, and laboratory procedures for performing such measurements. The tracer-velocity method is also briefly discussed.

Changes in cross-section geometry and channel volume in two reaches of the Kankakee River in Illinois, 1959-94

USGS Publications Warehouse

Terrio, Paul J.; Nazimek, John E.

1997-01-01

The upstream reaches of the Kankakee River in Indiana have been channelized, straightened, and ditched to facilitate agriculture; the downstream reaches of the river in Illinois have not been so altered. Concerns about the adjustments of this low-gradient river in response to these disturbances have led to studies of sedimentation along the Kankakee River in Illinois. The U.S. Geological Survey (USGS) began a study in 1992 to determine sedimentation characteristics of the Kankakee River in Illinois. As part of this study, changes in channel cross-section geometry and channel volume were determined by comparing measurements of cross-section geometry over time in two reaches of the Kankakee River. The study documents some of the adjustments of the Kankakee River to land-use changes and channelization in the upstream drainage area. The timing, magnitude, and process of adjustment are of interest in developing a better understanding of how alluvial stream systems in agricultural areas respond to disturbances in the drainage area. The data used for the study included cross-section measurements made by two State of Illinois agencies from 1959 to 1980 and measurements made by the USGS in 1994. The analyses indicated a net aggradation of about 133,600 cubic yards (yd3) of sediment in the Momence Wetlands reach, a naturally meandering reach of the river, from 1980 to 1994. Aggradation occurred at 25 cross sections in this reach, and scour occurred at 10 cross sections. All but one of the cross sections in the upstream third of the reach indicated aggradation, whereas aggradation and scour were found in the middle and downstream thirds of the reach. The magnitude of change was greatest in the middle third of the reach and was least in the downstream third of the reach. A net aggradation of approximately 298,600 yd3 of sediment was indicated for the Six-Mile Pool, a pooled reach of the river upstream from a dam, from 1978 to 1994. Approximately 182,900 yd3 of sediment accumulated from 1980 to 1994, and approximately 115,700 yd3 of sediment accumulated from 1978 to 1980. Most of the aggradation occurred in the middle third of the Six-Mile Pool reach.

Morphological assessment of reconstructed lowland streams in the Netherlands

NASA Astrophysics Data System (ADS)

Eekhout, Joris P. C.; Hoitink, Antonius J. F.; de Brouwer, Jan H. F.; Verdonschot, Piet F. M.

2015-07-01

Channelisation measures taken halfway the 20th century have had destructive consequences for the diversity of the ecology in the majority of the lowland streams in countries such as the Netherlands. Re-meandering is the common practice in restoring these lowland streams. Three reconstructed streams were monitored during the initial two years after construction of a new channel. The monitoring program included morphological surveys, sediment sampling, habitat pattern surveys, and discharge and water level measurements. Adjustments of the longitudinal bed profile formed the main morphological response. These adjustments were most likely caused by a lack of longitudinal connectivity of the streams as a whole, interrupting transport of sediment at locations of weirs and culverts. Bank erosion was observed only in a limited number of channel bends, and was often related to floodplain heterogeneity. Longitudinal channel bed adjustments and bank erosion were mainly caused by exogenous influences. In channel bends, the cross-sectional shape transformed from trapezoidal to the typical asymmetrical shape as found in meandering rivers. This behaviour can be attributed to an autogenous response to the prevailing flow conditions. Due to the prevailing fine sediment characteristics, bed material is readily set in motion and is being transported during the entire year. The existing design principles fail to address the initial morphological development after reconstruction. An evaluation of pre-set targets to realise water depth and flow velocity ranges shows the current procedures to be deficient. Based on this unfavourable evaluation, and the two-dimensional nature of habitat patterns needed to improve the conditions for stream organisms, we recommend to predict morphological developments as part of the design procedures for lowland stream restoration in the Netherlands.

Morphological Assessment of Reconstructed Lowland Streams in the Netherlands

NASA Astrophysics Data System (ADS)

Hoitink, T.; Eekhout, J.; de Brouwer, J.; Verdonschot, P.

2014-12-01

Channelisation measures taken halfway the 20th century have had destructive consequences for the diversity of the ecology in the majority of the lowland streams in countries such as the Netherlands. Re-meandering is the common practice in restoring these lowland streams. Three lowland streams were monitored during the initial two years after construction of a new channel. The monitoring program included morphological surveys, sediment sampling, habitat pattern surveys, and discharge and water level measurements. Adjustments of the longitudinal bed profile formed the main morphological response. These adjustments were most likely caused by a lack of longitudinal connectivity of the streams as a whole, interrupting transport of sediment at locations of weirs and culverts. Bank erosion was observed only in a limited number of channel bends, and was often related to floodplain heterogeneity. Longitudinal channel bed adjustments and bank erosion were mainly caused by exogenous influences. In channel bends, the cross-sectional shape transformed from trapezoidal to the typical asymmetrical shape as found in meandering rivers. This behaviour can be attributed to an autogenous response to the prevailing flow conditions. Due to the prevailing fine sediment characteristics, bed material is readily set in motion and is being transported during the entire year. The existing design principles fail to address the initial morphological development after reconstruction. An evaluation of pre-set targets to realize water depth and flow velocity ranges shows the current procedures to be deficient. Based on this unfavourable evaluation, and the two-dimensional nature of habitat patterns needed to improve the conditions for stream organisms, we recommend to predict morphological developments as part of the design procedures for lowland stream restoration in the Netherlands.

Aerodynamic Applications of Boundary Layer Control Using Embedded Streamwise Vortices

DTIC Science & Technology

2003-07-01

section, 0.02% free-stream turbulence level, free-stream velocity up to 18 m/s; the strain gauge can be used for aerodynamic force measurements. (2...section, free-stream velocity up to 28 m/s; equipped with the 3-component strain gauge (values of streamwise and normal forces measured up to 3N and 6...dimensional model: test section of 4m x 2.5m x 5.5m, free-stream velocities up to 42 m/s, multi-base 6-component strain gauge. Project Manager: Nina F

Dilution jets in accelerated cross flows. Ph.D. Thesis Final Report

NASA Technical Reports Server (NTRS)

Lipshitz, A.; Greber, I.

1984-01-01

Results of flow visualization experiments and measurements of the temperature field produced by a single jet and a row of dilution jets issued into a reverse flow combustor are presented. The flow in such combustors is typified by transverse and longitudinal acceleration during the passage through its bending section. The flow visualization experiments are designed to examine the separate effects of longitudinal and transverse acceleration on the jet trajectory and spreading rate. A model describing a dense single jet in a lighter accelerating cross flow is developed. The model is based on integral conservation equations, including the pressure terms appropriate to accelerating flows. It uses a modified entrainment correlation obtained from previous experiments of a jet in a cross stream. The flow visualization results are compared with the model calculations in terms of trajectories and spreading rates. Each experiment is typified by a set of three parameters: momentum ratio, density ratio and the densimetric Froude number.

Analysis of the injection of a heated turbulent jet into a cross flow

NASA Technical Reports Server (NTRS)

Campbell, J. F.; Schetz, J. A.

1973-01-01

The development of a theoretical model is investigated of the incompressible jet injection process. The discharge of a turbulent jet into a cross flow was mathematically modeled by using an integral method which accounts for natural fluid mechanisms such as turbulence, entrainment, buoyancy, and heat transfer. The analytical results are supported by experimental data and demonstrate the usefulness of the theory for estimating the trajectory and flow properties of the jet for a variety of injection conditions. The capability of predicting jet flow properties, as well as two- and three-dimensional jet paths, was enhanced by obtaining the jet cross-sectional area during the solution of the conservation equations. Realistic estimates of temperature in the jet fluid were acquired by accounting for heat losses in the jet flow due to forced convection and to entrainment of free-stream fluid into the jet.

Force Generation by Flapping Foils

NASA Astrophysics Data System (ADS)

Bandyopadhyay, P. R.; Donnelly, M.

1996-11-01

Aquatic animals like fish use flapping caudal fins to produce axial and cross-stream forces. During WW2, German scientists had built and tested an underwater vehicle powered by similar flapping foils. We have examined the forces produced by a pair of flapping foils. We have examined the forced produced by a pair of flapping foils attached to the tail end of a small axisymmetric cylinder. The foils operate in-phase (called waving), or in anti-phase (called clapping). In a low-speed water tunnel, we have undertaken time-dependent measurements of axial and cross-stream forces and moments that are exerted by the vortex shedding process over the entire body. Phase-matched LDV measurements of vorticity-velocity vectors, as well as limited flow visualization of the periodic vortex shedding process have also been carried out. The direction of the induced velocity within a pair of shed vortices determines the nature of the forces produced, viz., thrust or drag or cross-stream forces. The clapping mode produces a widely dispersed symmetric array of vortices which results in axial forces only (thrust and rag). On the other hand, the vortex array is staggered in the waving mode and cross-stream (maneuvering) forces are then generated.

Active Flow Control in an Aggressive Transonic Diffuser

NASA Astrophysics Data System (ADS)

Skinner, Ryan W.; Jansen, Kenneth E.

2017-11-01

A diffuser exchanges upstream kinetic energy for higher downstream static pressure by increasing duct cross-sectional area. The resulting stream-wise and span-wise pressure gradients promote extensive separation in many diffuser configurations. The present computational work evaluates active flow control strategies for separation control in an asymmetric, aggressive diffuser of rectangular cross-section at inlet Mach 0.7 and Re 2.19M. Corner suction is used to suppress secondary flows, and steady/unsteady tangential blowing controls separation on both the single ramped face and the opposite flat face. We explore results from both Spalart-Allmaras RANS and DDES turbulence modeling frameworks; the former is found to miss key physics of the flow control mechanisms. Simulated baseline, steady, and unsteady blowing performance is validated against experimental data. Funding was provided by Northrop Grumman Corporation, and this research used resources of the Argonne Leadership Computing Facility, which is a DOE Office of Science User Facility supported under Contract DE-AC02-06CH11357.

A comprehensive one-dimensional numerical model for solute transport in rivers

NASA Astrophysics Data System (ADS)

Barati Moghaddam, Maryam; Mazaheri, Mehdi; MohammadVali Samani, Jamal

2017-01-01

One of the mechanisms that greatly affect the pollutant transport in rivers, especially in mountain streams, is the effect of transient storage zones. The main effect of these zones is to retain pollutants temporarily and then release them gradually. Transient storage zones indirectly influence all phenomena related to mass transport in rivers. This paper presents the TOASTS (third-order accuracy simulation of transient storage) model to simulate 1-D pollutant transport in rivers with irregular cross-sections under unsteady flow and transient storage zones. The proposed model was verified versus some analytical solutions and a 2-D hydrodynamic model. In addition, in order to demonstrate the model applicability, two hypothetical examples were designed and four sets of well-established frequently cited tracer study data were used. These cases cover different processes governing transport, cross-section types and flow regimes. The results of the TOASTS model, in comparison with two common contaminant transport models, shows better accuracy and numerical stability.

Particle Size Characteristics of Fluvial Suspended Sediment in Proglacial Streams, King George Island, South Shetland Island

NASA Astrophysics Data System (ADS)

Szymczak, Ewa

2017-12-01

In this study, the characterization of particle size distribution of suspended sediment that is transported by streams (Ornithologist Creek, Ecology Glacier Creeks, Petrified Forest Creek, Czech Creek, Vanishing Creek, Italian Creek) in the area of the Arctowski Polish Antarctic Station is presented. During the first period of the summer season, the aforementioned streams are supplied by the melting snow fields, while later on, by thawing permafrost. The water samples were collected from the streams at monthly intervals during the Antarctic summer season (January - March) of 2016. The particle size distribution was measured in the laboratory with a LISST-25X laser diffraction particle size analyser. According to Sequoia Scientific Inc., LISST-25X can measure particle sizes (Sauter Mean Diameter) between 2.50 and 500 μm. The results of particle size measurements were analysed in relation to flow velocity (0.18-0.89 m/s), the cross-sectional parameters of the streams, suspended sediment concentration (0.06-167.22 mg/dm3) and the content of particulate organic matter (9.8-84.85%). Overall, the mean particle size ranged from 28.8 to 136 μm. The grain size of well-sorted sediments ranged from 0.076 to 0.57, with the skewness and kurtosis values varying from -0.1 to 0.4, and from 0.67 to 1.3, respectively. Based on the particle size characteristics of suspended sediment, the streams were divided into two groups. For most of the streams, the sediment was very well sorted, while fine sand and very fine sand were dominant fractions displaying symmetric and platykurtic distributions, respectively. Only in two streams, the suspended sediment consisted of silt-size grains, well or moderately well sorted, with coarse-skewness and mostly mesokurtic distribution. The C-M chart suggested that the transportation processes of suspended sediment included the suspended mode only. The grain-size distribution of suspended sediment was mainly influenced by the stream runoff, surface sediment type and biological processes.

Downstream reduction of rural channel size with contrasting urban effects in small coastal streams of southeastern Australia

NASA Astrophysics Data System (ADS)

Nanson, G. C.; Young, R. W.

1981-07-01

Although most streams show a downstream increase in channel size corresponding to a downstream increase in flood discharges, those flowing off the Illawarra escarpment of New South Wales show a marked reduction of channel size, accompanied by a down-stream increase in flood frequency in their lower reaches. Within the confined and steeply sloping valleys of the escarpment foothills, bed and bank sediments are relatively coarse and uncohesive, and channels increase in size, corresponding to increasing discharge downstream. However, once these streams emerge into more open rural valleys at lower slopes and are accompanied by extensive floodplains formed of fine cohesive sediment, there is a dramatic reduction in channel size. This decrease in channel size apparently results from a sudden decline in channel slope and associated stream power, the cohesive nature of downstream alluvium, its retention on the channel banks by a dense cover of pasture grasses, and the availability of an extensive floodplain to carry displaced floodwater. Under these conditions floodwaters very frequently spill out over the floodplain and the downstream channel-flow becomes a relatively unimportant component of the total peak discharge. This emphasizes the importance of these floodplains as a part of the total channel system. In situations where urban development has increased peak runoff and reduced the available area of effective floodplain, stream channels formed in this fine alluvium rapidly entrench and increase in cross-sectional area by 2-3 times. Minor man-induced channel alteration and maintenance appears to trigger this enlargement.

Flood effects on an Alaskan stream restoration project: the value of long-term monitoring

USGS Publications Warehouse

Densmore, Roseann V.; Karle, Kenneth F.

2009-01-01

On a nationwide basis, few stream restoration projects have long-term programs in place to monitor the effects of floods on channel and floodplain configuration and floodplain vegetation, but long-term and event-based monitoring is required to measure the effects of these stochastic events and to use the knowledge for adaptive management and the design of future projects. This paper describes a long-term monitoring effort (15 years) on a stream restoration project in Glen Creek in Denali National Park and Preserve in Alaska. The stream channel and floodplain of Glen Creek had been severely degraded over a period of 80 years by placer mining for gold, which left many reaches with unstable and incised streambeds without functioning vegetated floodplains. The objectives of the original project, initiated in 1991, were to develop and test methods for the hydraulic design of channel and floodplain morphology and for floodplain stabilization and riparian habitat recovery, and to conduct research and monitoring to provide information for future projects in similar degraded watersheds. Monitoring methods included surveyed stream cross-sections, vegetation plots, and aerial, ground, and satellite photos. In this paper we address the immediate and outlying effects of a 25-year flood on the stream and floodplain geometry and riparian vegetation. The long-term monitoring revealed that significant channel widening occurred following the flood, likely caused by excessive upstream sediment loading and the fairly slow development of floodplain vegetation in this climate. Our results illustrated design flaws, particularly in regard to identification and analysis of sediment sources and the dominant processes of channel adjustment.

Effects of an Experimental Enrichment of Instream Habitat Heterogeneity on the Stream Bed Morphology and Chironomid Community of a Straightened Section in a Sandy Lowland Stream

NASA Astrophysics Data System (ADS)

Spänhoff, Bernd; Riss, Wolfgang; Jäkel, Paul; Dakkak, Nadja; Meyer, Elisabeth I.

2006-02-01

A straightened stream stretch with poor habitat heterogeneity was divided into a “control” section with a low amount of submerged woody debris and an experimentally “wood-enriched” downstream section to study the effect of enhanced habitat diversity on the benthic invertebrate community. The downstream section was enriched by fixing 25 wood packages constructed from 9-10 branches on the stream bottom. Succession processes occurring in the two stream sections were compared by chironomid exuviae drift from July to November 2000 and from April to August 2001. During the first sampling period, more drifting chironomid exuviae (medians of control vs. wood-enriched: 446 vs. 331, no significant difference) and total number of taxa (44 vs. 36, Wilcoxon signed-rank test P = 0.019) were recorded for the control section. Although species compositions of both stream sections were highly similar (Sørensen index: 0.83) the diversity in the wood-enriched section was distinctly lower compared to the control section (Shannon-Weaver index: 1.19 vs. 1.50). During the second sampling period, exuviae numbers remained higher in the control section (median: 326 vs. 166), but total numbers of taxa were nearly equal (51 vs. 49), as well as species diversity (Shannon-Weaver index: 1.67 vs. 1.64). The lower chironomid diversity observed during the first sampling period coincided with a gradual but significant change of the streambed morphology in the wood-enriched section. There, the initially more U-shaped profile (V/U = 0.81 ± 0.37) had turned into a pronounced V shape (V/U = 1.14 ± 0.21), whereas the control section retained its unaltered U shape (V/U = 0.62-0.75). This small-scale study on experimental of woody debris in sandy lowland streams showed that the negative impact of increased hydraulic disturbance of the existing streambed more than outweighed any positive impact resulting from the increase in woody debris.

A Comparison of Hyporheic Transport at a Cross-Vane Structure and Natural Riffle.

PubMed

Smidt, Samuel J; Cullin, Joseph A; Ward, Adam S; Robinson, Jesse; Zimmer, Margaret A; Lautz, Laura K; Endreny, Theodore A

2015-01-01

While restoring hyporheic flowpaths has been cited as a benefit to stream restoration structures, little documentation exists confirming that constructed restoration structures induce comparable hyporheic exchange to natural stream features. This study compares a stream restoration structure (cross-vane) to a natural feature (riffle) concurrently in the same stream reach using time-lapsed electrical resistivity (ER) tomography. Using this hydrogeophysical approach, we were able to quantify hyporheic extent and transport beneath the cross-vane structure and the riffle. We interpret from the geophysical data that the cross-vane and the natural riffle induced spatially and temporally unique hyporheic extent and transport, and the cross-vane created both spatially larger and temporally longer hyporheic flowpaths than the natural riffle. Tracer from the 4.67-h injection was detected along flowpaths for 4.6 h at the cross-vane and 4.2 h at the riffle. The spatial extent of the hyporheic zone at the cross-vane was 12% larger than that at the riffle. We compare ER results of this study to vertical fluxes calculated from temperature profiles and conclude significant differences in the interpretation of hyporheic transport from these different field techniques. Results of this study demonstrate a high degree of heterogeneity in transport metrics at both the cross-vane and the riffle and differences between the hyporheic flowpath networks at the two different features. Our results suggest that restoration structures may be capable of creating sufficient exchange flux and timescales of transport to achieve the same ecological functions as natural features, but engineering of the physical and biogeochemical environment may be necessary to realize these benefits. © 2014, National Ground Water Association.

Leeward flow over delta wings at supersonic speeds

NASA Technical Reports Server (NTRS)

Szodruch, J. G.

1980-01-01

A survey was made of the parameters affecting the development of the leeward symmetric separated flow over slender delta wings immersed in a supersonic stream. The parameters included Mach number, Reynolds number, angle of attack, leading-edge sweep angle, and body cross-sectional shape, such that subsonic and supersonic leading-edge flows are encountered. It was seen that the boundaries between the various flow regimes existing about the leeward surface may conveniently be represented on a diagram with the components of angle of attack and Mach number normal to the leading edge as governing parameters.

Bankfull-channel geometry and discharge curves for the Rocky Mountains Hydrologic Region in Wyoming

USGS Publications Warehouse

Foster, Katharine

2012-01-01

Regional curves relate bankfull-channel geometry and bankfull discharge to drainage area in regions with similar runoff characteristics and are used to estimate the bankfull discharge and bankfull-channel geometry when the drainage area of a stream is known. One-variable, ordinary least-squares regressions relating bankfull discharge, cross-sectional area, bankfull width, and bankfull mean depth to drainage area were developed from data collected at 35 streamgages in or near Wyoming. Watersheds draining to these streamgages are within the Rocky Mountains Hydrologic Region of Wyoming and neighboring states.

Vapor generator wand

NASA Technical Reports Server (NTRS)

Robelen, David B. (Inventor)

1996-01-01

A device for producing a stream of vapor for wind tunnel airflow visualization is described. An electrically conductive heating tube is used to resistively heat a vapor producing liquid. The heating and delivery systems are integrated to allow the device to present a small cross section to the air flow, thereby reducing disturbances due to the device. The simplicity of the design allows for inexpensive implementation and construction. The design is readily scaled for use in various wind tunnel applications. The device may also find uses in manufacturing, producing a vapor for deposition on a substrate.

VARIATIONS IN MINERAL MATTER CONTENT OF A PEAT DEPOSIT IN MAINE RESTING ON GLACIO-MARINE SEDIMENTS.

USGS Publications Warehouse

Cameron, Cornelia C.; Schruben, Paul

1983-01-01

The Great Heath, Washington County, Maine, is an excellent example of a multidomed ombrotrophic peatland resting on a gently undulating surface of glacio-marine sediments and towering above modern streams. A comprehensive study sponsored by the Geological Survey of Maine in cooperation with the U. S. Geological Survey included preparation of a contoured surficial geology map on which are located 81 core sites. Eight cross sections accompany the map showing occurrence and thickness of three types of organic material and locations of cored sample analyses. Refs.

A revised velocity-reversal and sediment-sorting model for a high-gradient, pool-riffle stream

USGS Publications Warehouse

Thompson, D.M.; Wohl, E.E.; Jarrett, R.D.

1996-01-01

Sediment-sorting processes related to varying channel-bed morphology were investigated from April to November 1993 along a 1-km pool-riffle and step-pool reach of North Saint Vrain Creek, a small mountain stream in the Rocky Mountains of northern Colorado. Measured cross-sectional areas of flow were used to suggest higher velocities in pools than in riffles at high flow. Three hundred and sixteen tracer particles, ranging in size from 16 mm to 256 mm, were placed in two separate pool-riffle-pool sequences and used to assess sediment-sorting patterns and sediment-transport competence variations. Tracer-particle depositional evidence indicated higher sediment-transport competence in pools than in riffles at high flow. Pool-riffle sediment sorting may be created by velocity reversals, and more localized sorting results from gravitational forces along the upstream sloping portion of the channel bed located at the downstream end of pools.

Summary Report of Advanced Hydropower Innovations and Cost Reduction Workshop at Arlington, VA, November 5 & 6, 2015

DOE Office of Scientific and Technical Information (OSTI.GOV)

O'Connor, Patrick; Rugani, Kelsey; West, Anna

On behalf of the U.S. Department of Energy (DOE) Wind and Water Power Technology Office (WWPTO), Oak Ridge National Laboratory (ORNL), hosted a day and half long workshop on November 5 and 6, 2015 in the Washington, D.C. metro area to discuss cost reduction opportunities in the development of hydropower projects. The workshop had a further targeted focus on the costs of small, low-head1 facilities at both non-powered dams (NPDs) and along undeveloped stream reaches (also known as New Stream-Reach Development or “NSD”). Workshop participants included a cross-section of seasoned experts, including project owners and developers, engineering and construction experts,more » conventional and next-generation equipment manufacturers, and others to identify the most promising ways to reduce costs and achieve improvements for hydropower projects.« less

Empirical flow parameters : a tool for hydraulic model validity

USGS Publications Warehouse

Asquith, William H.; Burley, Thomas E.; Cleveland, Theodore G.

2013-01-01

The objectives of this project were (1) To determine and present from existing data in Texas, relations between observed stream flow, topographic slope, mean section velocity, and other hydraulic factors, to produce charts such as Figure 1 and to produce empirical distributions of the various flow parameters to provide a methodology to "check if model results are way off!"; (2) To produce a statistical regional tool to estimate mean velocity or other selected parameters for storm flows or other conditional discharges at ungauged locations (most bridge crossings) in Texas to provide a secondary way to compare such values to a conventional hydraulic modeling approach. (3.) To present ancillary values such as Froude number, stream power, Rosgen channel classification, sinuosity, and other selected characteristics (readily determinable from existing data) to provide additional information to engineers concerned with the hydraulic-soil-foundation component of transportation infrastructure.

"Data characterizing microfabricated human blood vessels created via hydrodynamic focusing".

PubMed

DiVito, Kyle A; Daniele, Michael A; Roberts, Steven A; Ligler, Frances S; Adams, André A

2017-10-01

This data article provides further detailed information related to our research article titled "Microfabricated Blood Vessels Undergo Neovascularization" (DiVito et al., 2017) [1], in which we report fabrication of human blood vessels using hydrodynamic focusing (HDF). Hydrodynamic focusing with advection inducing chevrons were used in concert to encase one fluid stream within another, shaping the inner core fluid into 'bullseye-like" cross-sections that were preserved through click photochemistry producing streams of cellularized hollow 3-dimensional assemblies, such as human blood vessels (Daniele et al., 2015a, 2015b, 2014, 2016; Roberts et al., 2016) [2], [3], [4], [5], [6]. Applications for fabricated blood vessels span general tissue engineering to organ-on-chip technologies, with specific utility in in vitro drug delivery and pharmacodynamics studies. Here, we report data regarding the construction of blood vessels including cellular composition and cell positioning within the engineered vascular construct as well as functional aspects of the tissues.

Sample stream distortion modeled in continuous-flow electrophoresis

NASA Technical Reports Server (NTRS)

Rhodes, P. H.

1979-01-01

Buoyancy-induced disturbances in an electrophoresis-type chamber were investigated. Five tracer streams (latex) were used to visualize the flows while a nine-thermistor array sensed the temperature field. The internal heating to the chamber was provided by a 400 Hz electrical field. Cooling to the chamber was provided on the front and back faces and, in addition, on both chamber side walls. Disturbances to the symmetric base flow in the chamber occurred in the broad plane of the chamber and resulted from the formation of lateral and axial temperature gradients. The effect of these gradients was to retard or increase local flow velocities at different positions in the chamber cross section, which resulted in lateral secondary flows being induced in the broad plane of the chamber. As the adverse temperature gradients increased in magnitude, the critical Rayleigh number was approached and reverse (separated) flow became apparent, which, subsequently, led to the onset of time variant secondary flows.

Development of regional curves relating bankfull-channel geometry and discharge to drainage area for streams in Pennsylvania and selected areas of Maryland

USGS Publications Warehouse

Chaplin, Jeffrey J.

2005-01-01

Natural-stream designs are commonly based on the dimensions of the bankfull channel, which is capable of conveying discharges that transport sediment without excessive erosion or deposition. Regional curves relate bankfull-channel geometry and discharge to drainage area in watersheds with similar runoff characteristics and commonly are utilized by practitioners of natural-stream design to confirm or refute selection of the field-identified bankfull channel. Data collected from 66 streamflow-gaging stations and associated stream reaches between December 1999 and December 2003 were used in one-variable ordinary least-squares regression analyses to develop regional curves relating drainage area to cross-sectional area, discharge, width, and mean depth of the bankfull channel. Watersheds draining to these stations are predominantly within the Piedmont, Ridge and Valley, and Appalachian Plateaus Physiographic Provinces of Pennsylvania and northern Maryland. Statistical analyses of physiography, percentage of watershed area underlain by carbonate bedrock, and percentage of watershed area that is glaciated indicate that carbonate bedrock, not physiography or glaciation, has a controlling influence on the slope of regional curves. Regional curves developed from stations in watersheds underlain by 30 percent or less carbonate bedrock generally had steeper slopes than the corresponding relations developed from watersheds underlain by greater than 30 percent carbonate bedrock. In contrast, there is little evidence to suggest that regional curves developed from stations in the Piedmont or Ridge and Valley Physiographic Province are different from the corresponding relations developed from stations in the Appalachian Plateaus Physiographic Province. On the basis of these findings, regional curves are presented to represent two settings that are independent of physiography: (1) noncarbonate settings characterized by watersheds with carbonate bedrock underlying 30 percent or less of watershed area, and (2) carbonate settings characterized by watersheds with carbonate bedrock underlying greater than 30 percent of watershed area. All regional curves presented in this report have slopes that are significantly different from zero and normally distributed residuals that vary randomly with drainage area. Drainage area explains the most variability in bankfull cross-sectional area and bankfull discharge in the noncarbonate setting (R2 = 0.92 for both). Less variability is explained in bankfull width and depth (R2 = 0.81 and 0.72, respectively). Regional curves representing the carbonate setting are generally not as statistically robust as the corresponding noncarbonate relations because there were only 11 stations available to develop these curves and drainage area cannot explain variance resulting from karst features. The carbonate regional curves generally are characterized by less confidence, lower R2 values, and higher residual standard errors. Poor representation by watersheds less than 40 mi2 causes the carbonate regional curves for bankfull discharge, cross-sectional area, and mean depth to be disproportionately influenced by the smallest watershed (values of Cook's Distance range from 3.6 to 8.4). Additional bankfull discharge and channel-geometry data from small watersheds might reduce this influence, increase confidence, and generally improve regional curves representing the carbonate setting. Limitations associated with streamflow-gaging station selection and development of the curves result in some constraints for the application of regional curves presented in this report. These curves apply only to streams within the study area in watersheds having land use, streamflow regulation, and drainage areas that are consistent with the criteria used for station selection. Regardless of the setting, the regional curves presented here are not intended for use as the sole method for estimation of bankfull characteristics; however, th

Methods and apparatus for carbon dioxide removal from a fluid stream

DOEpatents

Wei, Wei; Ruud, James Anthony; Ku, Anthony Yu-Chung; Ramaswamy, Vidya; Liu, Ke

2010-01-19

An apparatus for producing hydrogen gas wherein the apparatus includes a reactor. In one embodiment, the reactor includes at least two conversion-removal portions. Each conversion-removal portion comprises a catalyst section configured to convert CO in the stream to CO.sub.2 and a membrane section located downstream of and in flow communication with the catalyst section. The membrane section is configured to selectively remove the CO.sub.2 from the stream and to be in flow communication with a sweep gas.

Modeling sediment transport from an off-road vehicle trail stream crossing using WEPP model

Treesearch

Renee' D. Ayala; Puneet Srivastava; Christian J. Brodbeck; Emily A. Carter; Timothy P. McDonald

2005-01-01

There is a limited information available pertaining to the adverse effects of Off-Road-Vehicle (ORV) use and trail impacts. As a result, this study was initiated in 2003 to (a) quantify water quality impacts of an ORV trail stream crossing through monitoring of total suspended solids, and (b) conduct WEPP (Water Erosion Prediction Project) simulations to determine long...

Evaluation of erosion control BMPs on ditched haul road stream crossing approaches following reconstruction

Treesearch

A.J. Lang; W.M. Aust; M.C. Bolding; E.B. Schilling

2016-01-01

Ditched forest roads leading to stream crossings and used for log transportation have recently been a topic of water quality concern and legal controversy. Best management practices (BMPs) can reduce potential water quality issues, yet few research studies have quantified BMP costs and reductions in sediment from implementing specific ditch BMPs. Researchers...

On the dynamics of stream piracy

NASA Astrophysics Data System (ADS)

Goren, L.; Willett, S. D.

2012-04-01

Drainage network reorganization by stream piracy is invoked repeatedly to explain the morphology of unique drainage patterns and as a possible mechanism inducing abrupt variations of sediment accumulation rates. However, direct evidence of stream piracy is usually rare, and is highly interpretation dependent. As a first step in assessing how probable capture events are and establishing the conditions that favor stream piracy versus the those that favor stable landscapes, we formulate analytically the physics of divide migration and capture events and study this formulation from a dynamical system point of view. The formulation is based on a one-dimensional topographic cross section between two channels that share a water divide. Two hillslope profiles diverge from the divide and drain into two fluvial bedrock tributaries, whose erosion rate is controlled by a stream power law. The rate of erosion at the bounding channels is thus a function of the upstream drainage area and local slope. A tectonically induced downward perturbation of the elevation of one of the bounding channels lowers the channel slope but at the same time increases the drainage area due to outward migration of the water divide. The changes in slope and area have opposing effect on the erosion rate at the bounding channels, so that the perturbation may either grow or be damped. We define the geomorphic and tectonic parameters that control the behavior of the system and find the regimes that lead to stable landscapes and to capture events.

Hydrologic response of catchments to precipitation: Quantification of mechanical carriers and origins of water

NASA Astrophysics Data System (ADS)

Park, Y.-J.; Sudicky, E. A.; Brookfield, A. E.; Jones, J. P.

2011-12-01

Precipitation-induced overland and groundwater flow and mixing processes are quantified to analyze the temporal (event and pre-event water) and spatial (groundwater discharge and overland runoff) origins of water entering a stream. Using a distributed-parameter control volume finite-element simulator that can simultaneously solve the fully coupled partial differential equations describing 2-D Manning and 3-D Darcian flow and advective-dispersive transport, mechanical flow (driven by hydraulic potential) and tracer-based hydrograph separation (driven by dispersive mixing as well as mechanical flow) are simulated in response to precipitation events in two cross sections oriented parallel and perpendicular to a stream. The results indicate that as precipitation becomes more intense, the subsurface mechanical flow contributions tend to become less significant relative to the total pre-event stream discharge. Hydrodynamic mixing can play an important role in enhancing pre-event tracer signals in the stream. This implies that temporally tagged chemical signals introduced into surface-subsurface flow systems from precipitation may not be strong enough to detect the changes in the subsurface flow system. It is concluded that diffusive/dispersive mixing, capillary fringe groundwater ridging, and macropore flow can influence the temporal sources of water in the stream, but any sole mechanism may not fully explain the strong pre-event water discharge. Further investigations of the influence of heterogeneity, residence time, geomorphology, and root zone processes are required to confirm the conclusions of this study.

Field Training Activities for Hydrologic Science in West Java, Indonesia

NASA Astrophysics Data System (ADS)

Agustina, C.; Fajri, P. N.; Fathoni, F.; Gusti, T. P.; Harifa, A. C.; Hendra, Y.; Hertanti, D. R.; Lusiana, N.; Rohmat, F. I.; Agouridis, C.; Fryar, A. E.; Milewski, A.; Pandjaitan, N.; Santoso, R.; Suharyanto, A.

2013-12-01

In hydrologic science and engineering, one challenge is establishing a common framework for discussion among workers from different disciplines. As part of the 'Building Opportunity Out of Science and Technology: Helping Hydrologic Outreach (BOOST H2O)' project, which is supported by the U.S. Department of State, nine current or recent graduate students from four Indonesian universities participated in a week of training activities during June 2013. Students had backgrounds in agricultural engineering, civil and environmental engineering, water resources engineering, natural resources management, and soil science. Professors leading the training, which was based at Bogor Agricultural University (IPB) in west Java, included an agricultural engineer, civil engineers, and geologists. Activities in surface-water hydrology included geomorphic assessment of streams (measuring slope, cross-section, and bed-clast size) and gauging stream flow (wading with top-setting rods and a current meter for a large stream, and using a bucket and stopwatch for a small stream). Groundwater-hydrology activities included measuring depth to water in wells, conducting a pumping test with an observation well, and performing vertical electrical soundings to infer hydrostratigraphy. Students also performed relatively simple water-quality measurements (temperature, electrical conductivity, pH, and alkalinity) in streams, wells, and springs. The group analyzed data with commercially-available software such as AQTESOLV for well hydraulics, freeware such as the U.S. Geological Survey alkalinity calculator, and Excel spreadsheets. Results were discussed in the context of landscape position, lithology, and land use.

Relation between Working Memory Capacity and Auditory Stream Segregation in Children with Auditory Processing Disorder

PubMed Central

Lotfi, Yones; Mehrkian, Saiedeh; Moossavi, Abdollah; Zadeh, Soghrat Faghih; Sadjedi, Hamed

2016-01-01

Background: This study assessed the relationship between working memory capacity and auditory stream segregation by using the concurrent minimum audible angle in children with a diagnosed auditory processing disorder (APD). Methods: The participants in this cross-sectional, comparative study were 20 typically developing children and 15 children with a diagnosed APD (age, 9–11 years) according to the subtests of multiple-processing auditory assessment. Auditory stream segregation was investigated using the concurrent minimum audible angle. Working memory capacity was evaluated using the non-word repetition and forward and backward digit span tasks. Nonparametric statistics were utilized to compare the between-group differences. The Pearson correlation was employed to measure the degree of association between working memory capacity and the localization tests between the 2 groups. Results: The group with APD had significantly lower scores than did the typically developing subjects in auditory stream segregation and working memory capacity. There were significant negative correlations between working memory capacity and the concurrent minimum audible angle in the most frontal reference location (0° azimuth) and lower negative correlations in the most lateral reference location (60° azimuth) in the children with APD. Conclusion: The study revealed a relationship between working memory capacity and auditory stream segregation in children with APD. The research suggests that lower working memory capacity in children with APD may be the possible cause of the inability to segregate and group incoming information. PMID:26989281

Hydrologic response of catchments to precipitation: Quantification of mechanical carriers and origins of water

USGS Publications Warehouse

Park, Y.-J.; Sudicky, E.A.; Brookfield, A.E.; Jones, J.P.

2011-01-01

Precipitation-induced overland and groundwater flow and mixing processes are quantified to analyze the temporal (event and pre-event water) and spatial (groundwater discharge and overland runoff) origins of water entering a stream. Using a distributed-parameter control volume finite-element simulator that can simultaneously solve the fully coupled partial differential equations describing 2-D Manning and 3-D Darcian flow and advective-dispersive transport, mechanical flow (driven by hydraulic potential) and tracer-based hydrograph separation (driven by dispersive mixing as well as mechanical flow) are simulated in response to precipitation events in two cross sections oriented parallel and perpendicular to a stream. The results indicate that as precipitation becomes more intense, the subsurface mechanical flow contributions tend to become less significant relative to the total pre-event stream discharge. Hydrodynamic mixing can play an important role in enhancing pre-event tracer signals in the stream. This implies that temporally tagged chemical signals introduced into surface-subsurface flow systems from precipitation may not be strong enough to detect the changes in the subsurface flow system. It is concluded that diffusive/dispersive mixing, capillary fringe groundwater ridging, and macropore flow can influence the temporal sources of water in the stream, but any sole mechanism may not fully explain the strong pre-event water discharge. Further investigations of the influence of heterogeneity, residence time, geomorphology, and root zone processes are required to confirm the conclusions of this study. Copyright 2011 by the American Geophysical Union.

Assessing the Importance of Cross-Stream Transport in Bedload Flux Estimates from Migrating Dunes: Colorado River, Grand Canyon National Park

NASA Astrophysics Data System (ADS)

Leary, K. P.; Buscombe, D.; Schmeeckle, M.; Kaplinski, M. A.

2017-12-01

Bedforms are ubiquitous in sand-bedded rivers, and understanding their morphodynamics is key to quantifying bedload transport. As such, mechanistic understanding of the spatiotemporal details of sand transport through and over bedforms is paramount to quantifying total sediment flux in sand-bedded river systems. However, due to the complexity of bedform field geometries and migration in natural settings, our ability to relate migration to bedload flux, and to quantify the relative role of tractive and suspended processes in their dynamics, is incomplete. Recent flume and numerical investigations indicate the potential importance of cross-stream transport, a process previously regarded as secondary and diffusive, to the three-dimensionality of bedforms and spatially variable translation and deformation rates. This research seeks to understand and quantify the importance of cross-stream transport in bedform three-dimensionality in a field setting. This work utilizes a high-resolution (0.25 m grid) data set of bedforms migrating in the channel of the Colorado River in Grand Canyon National Park. This data set comprises multi-beam sonar surveys collected at 3 different flow discharges ( 283, 566, and 1076 m3/s) along a reach of the Colorado River just upstream of the Diamond Creek USGS gage. Data were collected every 6 minutes almost continuously for 12 hours. Using bed elevation profiles (BEPs), we extract detailed bedform geometrical data (i.e. bedform height, wavelength) and spatial sediment flux data over a suite of bedforms at each flow. Coupling this spatially extensive data with a generalized Exner equation, we conduct mass balance calculations that evaluate the possibility, and potential importance, of cross-stream transport in the spatial variability of translation and deformation rates. Preliminary results suggest that intra-dune cross-stream transport can partially account for changes in the planform shape of dunes and may play an important role in spatially variable translation and deformation rates. Parameterization of cross-stream sediment transport could lead to accounting for ambiguities in bedload flux calculations caused by dune deformation, which in turn could significantly improve overall calculation of bedload and total load sediment transport in sand bedded rivers.

Discharge of water and sediment from ice-streams on the southeastern Laurentide Ice Sheet during Heinrich events: timing and magnitude

NASA Astrophysics Data System (ADS)

Rashid, H.; Piper, D.

2017-12-01

Several ice-streams on the southeastern sector of the Laurentide Ice Sheet discharged icebergs, meltwater, and fine-grained sediments into the North Atlantic during Heinrich (H) events. The principal contribution was through Hudson Strait, which is the only source clearly identified in H ice-rafted layers in the central North Atlantic. The role of direct supply of meltwater in modifying the Atlantic meridional circulation generally has been regarded as secondary. The relative chronology of discharge in different ice-streams is poorly known. Here, we re-assess these questions using continental margin cores constrained by high-resolution seismic profiles and multibeam bathymetry data. Relative importance of ice streams likely scales with cross-sectional area of their erosional troughs. On that basis, the Hudson Strait ice stream was twice as large as that in the Laurentian Channel and 3-4 times larger than smaller troughs. Several ice streams supplied petrographically and geochemically distinct sediment including black shales from Cumberland Sound, limestone and dolomite in particular proportions from Frobisher Bay and Hudson Strait, and red sandstones and shales ± carbonates from NE Newfoundland and Laurentian Channel. In several cases, detrital carbonate H layers derived predominantly from Hudson Strait are preceded by enhanced IRD deposition from smaller ice streams, e.g. deposits from Cumberland Sound on the Labrador slope, from NE Newfoundland in Orphan Basin, and from Laurentian Channel on the Nova Scotian margin. Gravel petrology indicates that Hudson Strait sources make up >90% of the ice-rafted component of distal H layers. H layers proximal to the Hudson Strait ice-streams are 4 to 12 meters thick compared to a few centimeters thick seaward of the Trinity Trough and Laurentian ice-streams, comparable to the thickness of the North Atlantic. This underscores the great importance of meltwater and suspended sediment close to ice stream outlets. Morphological features and plume deposits show that meltwater becomes much more abundant in more southerly ice streams and some local plume deposits contribute to the thickness of H layers. The contribution of freshwater from melting icebergs and from direct meltwater discharge are approximately similar during H events.

An experimental investigation of a two and a three-dimensional low speed turbulent boundary layer

NASA Technical Reports Server (NTRS)

Winkelmann, A. E.; Melnik, W. L.

1976-01-01

Experimental studies of a two and a three-dimensional low speed turbulent boundary layer were conducted on the side wall of a boundary layer wind tunnel. The 20 ft. long test section, with a rectangular cross section measuring 17.5 in. x 46 in., produced a 3.5 in. thick turbulent boundary layer at a free stream Reynolds number. The three-dimensional turbulent boundary layer was produced by a 30 deg swept wing-like model faired into the side wall of the test section. Preliminary studies in the two-dimensional boundary layer indicated that the flow was nonuniform on the 46 in. wide test wall. The nonuniform boundary layer is characterized by transverse variations in the wall shear stress and is primarily caused by nonuniformities in the inlet damping screens.

Reconnaissance of Stream Geomorphology, Low Streamflow, and Stream Temperature in the Mountaintop Coal-Mining Region, Southern West Virginia, 1999-2000

USGS Publications Warehouse

Wiley, Jeffrey B.; Evaldi, Ronald D.; Eychaner, James H.; Chambers, Douglas B.

2001-01-01

The effects of mountaintop removal coal mining and the valley fills created by this mining method in southern West Virginia were investigated by comparing data collected at valley-fill, mined, and unmined sites. Bed material downstream of valley-fill sites had a greater number of particles less than 2 millimeters and a smaller median particle size than the mined and unmined sites. At the 84th percentile of sampled data, however, bed material at each site type had about the same size particles. Bankfull cross-sectional areas at a riffle section were approximately equal at valley-fill and unmined sites, but not enough time has passed and insufficient streamflows since the land was disturbed may have prevented the stream channel at valley-fill sites from reaching equilibrium. The 90-percent flow durations at valley-fill sites generally were 6-7 times greater than at unmined sites. Some valley-fill sites, however, exhibited streamflows similar to unmined sites, and some unmined sites exhibited streamflows similar to valley-fill sites. Daily streamflows from valley-fill sites generally are greater than daily streamflows from unmined sites during periods of low streamflow. Valley-fill sites have a greater percentage of base-flow and a lower percentage of flow from storm runoff than unmined sites. Water temperatures from a valley-fill site exhibited lower daily fluctuations and seasonal variations than water temperatures from an unmined site.

Experiments in a three-dimensional adaptive-wall wind tunnel

NASA Technical Reports Server (NTRS)

Schairer, E. T.

1983-01-01

Three dimensional adaptive-wall experiments were performed in the Ames Research Center (ARC) 25- by 13-cm indraft wind tunnel. A semispan wing model was mounted to one sidewall of a test section with solid sidewalls, and slotted top and bottom walls. The test section had separate top and bottom plenums which were divided into streamwise and cross-stream compartments. An iterative procedure was demonstrated for measuring wall interference and for adjusting the plenum compartment pressures to eliminate such interference. The experiments were conducted at a freestream Mach number of 0.60 and model angles of attack between 0 and 6 deg. Although in all the experiments wall interference was reduced after the plenum pressures were adjusted, interference could not be completely eliminated.

A New Approach to Scaling Channel Width in Bedrock Rivers and its Implications for Modeling Fluvial Incision

NASA Astrophysics Data System (ADS)

Finnegan, N. J.; Roe, G.; Montgomery, D. R.; Hallet, B.

2004-12-01

The fundamental role of bedrock channel incision on the evolution of mountainous topography has become a central concept in tectonic geomorphology over the past decade. During this time the stream power model of bedrock river incision has immerged as a valuable tool for exploring the dynamics of bedrock river incision in time and space. In most stream power analyses, river channel width--a necessary ingredient for calculating power or shear stress per unit of bed area--is assumed to scale solely with discharge. However, recent field-based studies provide evidence for the alternative view that channel width varies locally, much like channel slope does, in association with spatial changes in rock uplift rate and erodibility. This suggests that simple scaling relations between width and discharge, and hence estimates of stream power, don't apply in regions where rock uplift and erodibility vary spatially. It also highlights the need for an alternative to the traditional assumptions of hydraulic geometry to further investigation of the coupling between bedrock river incision and tectonic processes. Based on Manning's equation, basic mass conservation principles, and an assumption of self-similarity for channel cross sections, we present a new relation for scaling the steady-state width of bedrock river channels as a function of discharge (Q), channel slope (S), and roughness (Ks): W \\propto Q3/8S-3/16Ks1/16. In longitudinally simple, uniform-concavity rivers from the King Range in coastal Northern California, the model emulates traditional width-discharge relations that scale channel width with the square root of discharge. More significantly, our relation describes river width trends for the Yarlung Tsangpo in SE Tibet and the Wenatchee River in the Washington Cascades, both rivers that narrow considerably as they incise terrain with spatially varied rock uplift rates and/or lithology. We suggest that much of observed channel width variability is a simple consequence of the tendency for water to flow faster in steeper reaches and therefore maintain smaller channel cross sections. We demonstrate that using conventional scaling relations for bedrock channel width can significantly underestimate stream power variability in bedrock channels, and that our model improves estimates of spatial patterns of bedrock incision rates.

Extreme erosion response after wildfire in the Upper Ovens, south-east Australia: Assessment of catchment scale connectivity by an intensive field survey

NASA Astrophysics Data System (ADS)

Box, Walter; Keestra, Saskia; Nyman, Petter; Langhans, Christoph; Sheridan, Gary

2015-04-01

South-eastern Australia is generally regarded as one of the world's most fire-prone environments because of its high temperatures, low rainfall and flammable native Eucalyptus forests. Modifications to the landscape by fire can lead to significant changes to erosion rates and hydrological processes. Debris flows in particular have been recognised as a process which increases in frequency as a result of fire. This study used a debris flow event in the east Upper Ovens occurred on the 28th of February 2013 as a case study for analysing sediment transport processes and connectivity of sediment sources and sinks. Source areas were identified using a 15 cm resolution areal imagery and a logistic regression model was made based on fire severity, aridity index and slope to predict locations of source areas. Deposits were measured by making cross-sections using a combination of a differential GPS and a total station. In total 77 cross-sections were made in a 14.1 km2 sub-catchment and distributed based on channel gradient and width. A more detailed estimation was obtained by making more cross-sections where the volume per area is higher. Particle size distribution between sources and sink areas were obtained by combination of field assessment, photography imagery analyses and sieve and laser diffraction. Sediment was locally eroded, transported and deposited depending on factors such as longitude gradient, stream power and the composition of bed and bank material. The role of headwaters as sediment sinks changed dramatically as a result of the extreme erosion event in the wildfire affected areas. Disconnected headwaters became connected to low order streams due to debris flow processes in the contributing catchment. However this redistribution of sediment from headwaters to the drainage network was confined to upper reaches of the Ovens. Below this upper part of the catchment the event resulted in redistribution of sediment already existing in the channel through a combination of debris flows and hyperconcentrated flows. These results indicate that there is a stepwise outflow of sediment influencing long-term erosion rates and landform development.

Metal poisons for criticality in waste streams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williamson, T.G.; Goslen, A.Q.

1996-12-31

Many of the wastes from processing fissile materials contain metals that may serve as neutron poisons. It would be advantageous to the criticality evaluation of these wastes to demonstrate that the poisons remain with the fissile materials and to demonstrate an always safe poison-to-fissile ratio. The first task, demonstrating that the materials stay together, is the job of the chemist; the second, calculating an always safe ratio, is an object of this paper. In an earlier study, the authors demonstrated safe ratios for iron, manganese, and chromium oxides to {sup 235}U. In these studies, the Hansen-Roach 16-group cross sections weremore » used with the Savannah River site code HRXN. Multiplication factors were computed, and safe ratios were defined such that the adjusted neutron multiplication factors (k values) were <0.95. These safe weight ratios were Fe:{sup 235}U - 77:1; Mn:{sup 235}U - 30:1; and Cr:{sup 235}U - 52:1. Palmer has shown that for certain mixtures of aluminum, iron, and zirconium with {sup 235}U, the computed infinite multiplication factors may differ by as much as 20% with different cross sections and processing systems. Parks et al. have further studied these mixtures and state, {open_quotes}...these metal/uranium mixtures are very sensitive to the metal cross-section data in the intermediate-energy range and the processing methods that are used.{close_quotes} They conclude with a call for more experimental data. The purpose of this study is to reexamine earlier work with cross sections and processing codes used at Westinghouse Savannah River Company today. This study will focus on {sup 235}U mixtures with iron, manganese and chromium. Sodium will be included in the list of poisons because it is abundant in many of the waste materials.« less

Water quality impacts from an ORV trail stream crossing in the Talladega National Forest, Alabama, USA

Treesearch

Renee D. Ayala; Puneet Srivastava; Christian J. Brodbeck; Emily a. Carter; Timothy P. McDonald

2005-01-01

Off-Road Vehicles (ORVs) are one of the most damaging forms of recreation utilized in our National Forests. Erosion from ORV trails can be a major source of water quality impact. In 2003, a study was initiated in the Talladega National Forest to quantifjl water quality impacts of an ORV trail crossing a local stream. Automated samplers were installed upstream and...

Voluntary Blood Donation among Students - A Cross-Sectional Study on Knowledge and Practice vs. Attitude

PubMed Central

Pehlajani, Nand K.; Sinha, Mithilesh K.

2016-01-01

Introduction The factors influencing blood donation decisions are varied and complex and one’s attitude can influence this decision. Aim To find the factors affecting the knowledge and practice of blood donation among college students and their attitude towards the same. Materials and Methods This cross-sectional study was conducted among 399 college going students using convenience sampling from medical, nursing and engineering colleges in Bhubaneswar city, where blood donation camps were to be held. Data was collected through self-administered questionnaires and, analysed in SPSS Version 20.0. Results Knowledge regarding blood donation was adequate among 228 (57.1%) of the students and, 221 (55.4%) students had donated blood. Knowledge was significantly better among female students, medical stream and in those whose parents were in non-medical jobs; whereas blood donation had been done significantly more by male, non-medical stream students and by those whose parents were in medical field. Most common reason for donating blood was a sense of social responsibility and most common reason of non-donation was fear of the procedure. An 85% of the students were of the view that they would donate blood if asked. Students suggested that small incentives like certificates and arranging transport for blood donation would make it easier to donate. Conclusion Just over half of the students had adequate knowledge about blood donation and similar percentage had donated blood. There is this large pool of safe blood in college going students who are willing, but not tapped as source of blood donation. PMID:27891345

Exploring lag times between monthly atmospheric deposition and stream chemistry in Appalachian forests using cross-correlation

NASA Astrophysics Data System (ADS)

DeWalle, David R.; Boyer, Elizabeth W.; Buda, Anthony R.

2016-12-01

Forecasts of ecosystem changes due to variations in atmospheric emissions policies require a fundamental understanding of lag times between changes in chemical inputs and watershed response. Impacts of changes in atmospheric deposition in the United States have been documented using national and regional long-term environmental monitoring programs beginning several decades ago. Consequently, time series of weekly NADP atmospheric wet deposition and monthly EPA-Long Term Monitoring stream chemistry now exist for much of the Northeast which may provide insights into lag times. In this study of Appalachian forest basins, we estimated lag times for S, N and Cl by cross-correlating monthly data from four pairs of stream and deposition monitoring sites during the period from 1978 to 2012. A systems or impulse response function approach to cross-correlation was used to estimate lag times where the input deposition time series was pre-whitened using regression modeling and the stream response time series was filtered using the deposition regression model prior to cross-correlation. Cross-correlations for S were greatest at annual intervals over a relatively well-defined range of lags with the maximum correlations occurring at mean lags of 48 months. Chloride results were similar but more erratic with a mean lag of 57 months. Few high-correlation lags for N were indicated. Given the growing availability of atmospheric deposition and surface water chemistry monitoring data and our results for four Appalachian basins, further testing of cross-correlation as a method of estimating lag times on other basins appears justified.

40 CFR 63.2485 - What requirements must I meet for wastewater streams and liquid streams in open systems within an...

Code of Federal Regulations, 2011 CFR

2011-07-01

... wastewater streams and liquid streams in open systems within an MCPU? 63.2485 Section 63.2485 Protection of... Compliance Requirements § 63.2485 What requirements must I meet for wastewater streams and liquid streams in... to your wastewater streams and liquid streams in open systems within an MCPU, except as specified in...

Factors of Stream Instability in Urban Centres of Southern Nigeria: Case Study of Port Harcourt City River Systems.

NASA Astrophysics Data System (ADS)

Amangabara, G. T.

2006-05-01

There are two main drainage rivers in the Port Harcourt Metropolis - The Ntamogba and the Woji creek (Abam, 2004). There are a few other drainage rivers that are equally important e.g. the Nwaja River that drains Rumukalagbor, Elekahia, New GRA Phases IV and V, Presidential Housing Estate and Sun Ray publications Area of Aba Road. These river systems drain the entire Port Harcourt City dividing the City into three major drainage zones. Since the discovery of oil in Nigeria in the 1950s, the country has been suffering the negative environmental consequences of oil development. The growth of the country's oil industry, combined with population explosion and a lack of environmental regulations, led to substantial damage to Nigeria's environment, especially in the Niger Delta region, the center of the country's oil industry. Uncontrolled population movement as well as spontaneous housing development on marginal lands such as stream corridors, has led to the degradation of all major stream channels in the Nation's oil capital - Port Harcourt City. The longitudinal profiles and cross sections of reaches of three major streams (Ntamogba, Nwaja, and Oginigba streams) were investigated. Land use maps of 1979 1999 and 2004 were used. Our result showed that 1). Almost all of the stream corridors have been built up without adequate plan 2). The natural grades have been distorted by channelisation for the purpose of flood evacuation without geomorphic consideration .3). Our research also shows that the interface of saline water and fresh water has extended upstream affecting urban infrastructure. 4) localized damming and sedimentation behind hydraulic structures were common occurrences) our overall result indicate that two episodes of channel incision on Oginigba stream had increased slope reduced sinuosity increased entrenchment and reduce width-depth ratio . Conclusively the factors of the instability of theses urban streams are manly the processes of urbanization which include waste dumping channelisation and unregulated housing development in the channel corridors. KEY WORDS: stream instability, marginal lands, stream corridor, saline environment, spontaneous, geomorphic, channelisation

How Does Decommissioning Forest Roads Effect Hydrologic and Geomorphic Risk?

NASA Astrophysics Data System (ADS)

Black, T.; Luce, C.; Cissel, R. M.; Nelson, N.; Staab, B.

2010-12-01

The US Forest Service is investigating road decommissioning projects to understand how treatments change hydrologic and geomorphic risks. Road treatment effect was measured using a before after control impact design (BACI), using the Geomorphic Road Analysis and Inventory Package (http://www.fs.fed.us/GRAIP). This suite of inventory and analysis tools evaluates: road-stream hydrologic connectivity, fine sediment production and delivery, shallow landslide risk, gully initiation risk, and risks associated with stream crossing failures. The Skokomish River study site is steep and wet and received a high intensity treatment including the removal of stream crossing pipes and fills, all ditch relief pipes and a full hillslope recontouring. Road to stream hydrologic connectivity was reduced by 70%. The treatments reduced fine sediment delivery by 21.8 tons or 81%. The removal of the stream crossing culverts and large associated road fills eliminated the risk of pipe plugging related failures and the eventual erosion of over 4,000 m3 of fill. The slope stability risk was assessed using a modified version of SINMAP (Pack et al, 2005). Risk below drain point locations on the original road was reduced as water was redistributed across the hillslope to waterbars and diffuse drainage. It is unclear; however, if landslide risk was reduced across the entire treated road length because treatments slightly increased risk in some areas where new concentrated drainage features were added above steep slopes. Similarly, values of a gully index ESI (Istanbulluoglu et al, 2003), were reduced at many of the original drainage points, however some new drainage was added. ESI values still exceed a predicted conservative initiation thresholds at some sites, therefore it is uncertain if gully risk will be changed. Mann Creek occupies a moderately steep mid-elevation site in Southern Idaho. The high intensity treatments removed all constructed road drainage features including stream crossing pipes and fills, and recontoured the hillslope. The length of road that was hydrologically connected to streams was reduced by 2,923 m, or 97%. The model predicts that fine sediment delivery was reduced by 98%, to 1.0 ton annually. The risk presented by stream crossings becoming plugged was eliminated. The potential for streamflow diversion onto roads and hillslopes was precluded. The slope stability risk below drain point locations on the original road was reduced as water was no longer concentrated and discharged through a single drainage feature. Treatments are predicted to return slope stability to near undisturbed levels. Gully initiation risks, already low prior to treatment, may be reduced to negligible values. Results from these two case studies suggest that high intensity road decommissioning can be effective at reducing the risk of road sediment delivery, hydrologic connectivity and failures associated with stream crossings. Post storm monitoring will help validate these predictions and reduce uncertainty around the hydrology of decommissioned roads. If decommissioned roads continue to concentrate water and discharge it onto steep slopes, landslides and gully risk may remain elevated.

Application of Integral Pumping Tests to estimate the influence of losing streams on groundwater quality

NASA Astrophysics Data System (ADS)

Leschik, S.; Musolff, A.; Reinstorf, F.; Strauch, G.; Schirmer, M.

2009-05-01

Urban streams receive effluents of wastewater treatment plants and untreated wastewater during combined sewer overflow events. In the case of losing streams substances, which originate from wastewater, can reach the groundwater and deteriorate its quality. The estimation of mass flow rates Mex from losing streams to the groundwater is important to support groundwater management strategies, but is a challenging task. Variable inflow of wastewater with time-dependent concentrations of wastewater constituents causes a variable water composition in urban streams. Heterogeneities in the structure of the streambed and the connected aquifer lead, in combination with this variable water composition, to heterogeneous concentration patterns of wastewater constituents in the vicinity of urban streams. Groundwater investigation methods based on conventional point sampling may yield unreliable results under these conditions. Integral Pumping Tests (IPT) can overcome the problem of heterogeneous concentrations in an aquifer by increasing the sampled volume. Long-time pumping (several days) and simultaneous sampling yields reliable average concentrations Cav and mass flow rates Mcp for virtual control planes perpendicular to the natural flow direction. We applied the IPT method in order to estimate Mex of a stream section in Leipzig (Germany). The investigated stream is strongly influenced by combined sewer overflow events. Four pumping wells were installed up- and downstream of the stream section and operated for a period of five days. The study was focused on four inorganic (potassium, chloride, nitrate and sulfate) and two organic (caffeine and technical-nonylphenol) wastewater constituents with different transport properties. The obtained concentration-time series were used in combination with a numerical flow model to estimate Mcp of the respective wells. The difference of the Mcp's between up- and downstream wells yields Mex of wastewater constituents that increase downstream of the stream. In order to confirm the obtained Mcp's concentrations of additional measurements in the investigated stream were compared with the concentrations in the groundwater up- and downstream of the stream section. The results revealed increased Mcp's downstream of the stream section for chloride, potassium and nitrate, whereas Mcp of sulfate was decreased. Micropollutants caffeine and technical-nonylphenol showed decreased Mcp's downstream of the stream section in 75 % of the cases. Values of Mex could only be given for chloride, potassium, nitrate and caffeine. The comparison of concentrations in the stream with those in the groundwater points to the streambed as a zone where mass accumulation and degradation processes occur. The obtained results imply that the applied method can provide reliable data about the influence of losing streams on groundwater quality.

Vegetation Impacts on Near Bank Flows

NASA Astrophysics Data System (ADS)

Hopkinson, L. C.; Wynn, T. M.

2008-12-01

Sediment, a leading cause of water quality impairment, damages aquatic ecosystems and interferes with recreational uses and water treatment processes. A significant sediment source to streams, streambank retreat, has largely been ignored. Vegetation is an important component of stream restoration designs used to control streambank retreat, but vegetation effects on near bank flows need to be quantified. The goal of this research is to evaluate the effects of streambank vegetation on near bank flows and boundary shear stress. A flume experiment was conducted comparing three distinct streambank vegetation types: trees, shrubs, and grass. A second order prototype stream (Tom's Creek in Blacksburg, VA), with individual reaches dominated by the vegetation treatments was modeled using a fixed-bed Froude-scale modeling technique. One model streambank of the prototype stream was constructed for each vegetation type and compared to a bare control (only grain roughness). Simulated vegetation (e.g. woven grass mat and wooden dowels) was attached in locations identified in a field survey. Velocity profiles perpendicular to the flume model boundary will be evaluated along five cross sections for each vegetation treatment. Reynolds, law of the wall, and turbulent kinetic energy shear stresses will be analyzed using velocity measurements made with a three-dimensional acoustic Doppler velocimeter (ADV). Velocity profiles perpendicular to the flume model streambank will also be evaluated. The velocity profiles will be compared among vegetation types to see if profiles are similar along the bank face. This research is intended to improve our understanding of the role of riparian vegetation in stream morphology by evaluating the effects of vegetation on boundary shear stress, providing insight to the type and density of vegetation required for streambank stability. The results will also aide in quantifying sediment inputs from streambanks, providing quantitative information for stream restoration projects and watershed management planning.

40 CFR 63.2485 - What requirements must I meet for wastewater streams and liquid streams in open systems within an...

Code of Federal Regulations, 2012 CFR

2012-07-01

... wastewater streams and liquid streams in open systems within an MCPU? 63.2485 Section 63.2485 Protection of... Standards, and Compliance Requirements § 63.2485 What requirements must I meet for wastewater streams and... subpart that applies to your wastewater streams and liquid streams in open systems within an MCPU, except...

40 CFR 63.2485 - What requirements must I meet for wastewater streams and liquid streams in open systems within an...

Code of Federal Regulations, 2013 CFR

2013-07-01

... wastewater streams and liquid streams in open systems within an MCPU? 63.2485 Section 63.2485 Protection of... Standards, and Compliance Requirements § 63.2485 What requirements must I meet for wastewater streams and... subpart that applies to your wastewater streams and liquid streams in open systems within an MCPU, except...

40 CFR 63.2485 - What requirements must I meet for wastewater streams and liquid streams in open systems within an...

Code of Federal Regulations, 2014 CFR

2014-07-01

... wastewater streams and liquid streams in open systems within an MCPU? 63.2485 Section 63.2485 Protection of... Standards, and Compliance Requirements § 63.2485 What requirements must I meet for wastewater streams and... subpart that applies to your wastewater streams and liquid streams in open systems within an MCPU, except...

Aquatic organism passage at road-stream crossings—synthesis and guidelines for effectiveness monitoring

Treesearch

Robert L. Hoffman; Jason B. Dunham; Bruce P. Hansen

2012-01-01

Restoration and maintenance of passage for aquatic organisms at road-stream crossings represents a major management priority, involving an investment of hundreds of millions of dollars. This report has been written, in part, for field biologists who will be undertaking and evaluating the effectiveness of aquatic organism passage restoration projects at road-stream...

Techniques for Minimizing and Monitoring the Impact of Pipeline Construction on Coastal Streams

Treesearch

Thomas W. Mulroy; John R. Storrer; Vincent J. Semonsen; Michael L. Dungan

1989-01-01

This paper describes specific measures recently employed for protection of riparian resources during construction of an oil and gas pipeline that crossed coastal reaches of 23 perennial and intermittent streams between Point Conception and Gaviota in Santa Barbara County, California. Flumes were constructed to maintain stream flow; anchored straw bales and silt fences...

Algal-bacterial co-variation in streams: a cross-stream comparison

Treesearch

Xueqing Gao; Ola A. Olapade; Mark W. Kershner; Laura G. Leff

2004-01-01

Algal-bacterial co-variation has been frequently observed in lentic and marine environments, but the existence of such relationships in lotic ecosystems is not well established. To examine possible co-variation, bacterial number and chlorophyll-a concentration in water and sediments of nine streams from different regions in the USA were examined. In the water, a strong...

Alternative stream channel maintenance at bridge crossings : final report.

DOT National Transportation Integrated Search

2017-02-01

Ohio Department of Transportation (ODOT) forces undertake routine and sometimes extensive maintenance of stream channels that impact the performance and safety of bridges. Unfortunately, county crews have limited options available to solve maintenanc...

Instream cover and shade mediate avian predation on trout in semi-natural streams

USGS Publications Warehouse

Penaluna, Brooke E.; Dunham, Jason B.; Noakes, David L. G.

2015-01-01

Piscivory by birds can be significant, particularly on fish in small streams and during seasonal low flow when available cover from predators can be limited. Yet, how varying amounts of cover may change the extent of predation mortality from avian predators on fish is not clear. We evaluated size-selective survival of coastal cutthroat trout (Oncorhynchus clarkii clarkii) in replicated semi-natural stream sections. These sections provided high (0.01 m2 of cover per m2 of stream) or low (0.002 m2 of cover per m2 of stream) levels of instream cover available to trout and were closed to emigration. Each fish was individually tagged, allowing us to track retention of individuals during the course of the 36-day experiment, which we attributed to survival from predators, because fish had no other way to leave the streams. Although other avian predators may have been active in our system and not detected, the only predator observed was the belted kingfisher Megaceryle alcyon, which is known to prey heavily on fish. In both treatments, trout >20.4 cm were not preyed upon indicating an increased ability to prey upon on smaller individuals. Increased availability of cover improved survival of trout by 12% in high relative to low cover stream sections. Trout also survived better in stream sections with greater shade, a factor we could not control in our system. Collectively, these findings indicate that instream cover and shade from avian predators can play an important role in driving survival of fish in small streams or during periods of low flow.

Geomorphology and till architecture of terrestrial palaeo-ice streams of the southwest Laurentide Ice Sheet: A borehole stratigraphic approach

NASA Astrophysics Data System (ADS)

Norris, Sophie L.; Evans, David J. A.; Cofaigh, Colm Ó.

2018-04-01

A multidimensional study, utilising geomorphological mapping and the analysis of regional borehole stratigraphy, is employed to elucidate the regional till architecture of terrestrial palaeo-ice streams relating to the Late Wisconsinan southwest Laurentide Ice Sheet. Detailed mapping over a 57,400 km2 area of southwestern Saskatchewan confirms previous reconstructions of a former southerly flowing ice stream, demarcated by a 800 km long corridor of megaflutes and mega-scale glacial lineations (Ice Stream 1) and cross cut by three, formerly southeast flowing ice streams (Ice Streams 2A, B and C). Analysis of the lithologic and geophysical characteristics of 197 borehole samples within these corridors reveals 17 stratigraphic units comprising multiple tills and associated stratified sediments overlying preglacial deposits, the till thicknesses varying with both topography and distance down corridor. Reconciling this regional till architecture with the surficial geomorphology reveals that surficial units are spatially consistent with a dynamic switch in flow direction, recorded by the cross cutting corridors of Ice Streams 1, 2A, B and C. The general thickening of tills towards lobate ice stream margins is consistent with subglacial deformation theory and variations in this pattern on a more localised scale are attributed to influences of subglacial topography including thickening at buried valley margins, thinning over uplands and thickening in overridden ice-marginal landforms.

Interhemispheric comparison of atmospheric circulation features as evaluated from Nimbus satellite data

NASA Technical Reports Server (NTRS)

Reiter, E. R.; Vonderhaar, T. H.; Adler, R. F.; Srivatsangam, S.; Fields, A.

1973-01-01

A relationship is established between relative geostrophic vorticity on an isobaric surface and the Laplacian of the underlying layer-mean temperature. This relationship is used to investigate the distribution of vorticity and baroclinicity in a jet-stream model which is constantly recurrent in the winter troposphere. The investigation shows that the baroclinic and vorticity fields of the extratropical troposphere must be bifurcated with two extrema in the middle and subpolar latitudes. This pattern is present in daily tropospheric meridional cross-sections. The reasons for the disappearance of bifurcation in the time-and-longitude averaged distributions are discussed.

Sediment sources in the Lake Tahoe Basin, California-Nevada; preliminary results of a four-year study, August 1983-September 1987

USGS Publications Warehouse

Hill, B.R.; Hill, J.R.; Nolan, K.M.

1988-01-01

Data were collected during a 4-yr study of sediment sources in four drainage basins tributary to Lake Tahoe, California-Nevada. The study areas include the Blackwood, General, Edgewood, and Logan House Creek basins. Data include changes in bank and bed positions at channel cross sections; results of stream-channel mapping; analyses of bank and bed material samples; tabulations of bed material point counts; measured rates of hillslope erosion; dimensions of gullies; suspended-sediment data collected during synoptic snowmelt sampling; and physiographic data for the four study basins. (USGS)

Sediment-source data for four basins tributary to Lake Tahoe, California and Nevada; August 1983-June 1988

USGS Publications Warehouse

Hill, B.R.; Hill, J.R.; Nolan, K.M.

1990-01-01

Data were collected during a 5-year study of sediment sources in four drainage basins tributary to Lake Tahoe, California-Nevada. The study areas include the Blackwood Creek, General Creek, Edgewood Creek, and Logan House Creek basins. Data include changes in bank and bed positions at channel cross sections; results of stream-channel inventories; analyses of bank and bed material samples; tabulations of bed-material pebble counts; measured rates of hillslope erosion; dimensions of gullies; suspended-sediment data collected during synoptic snowmelt sampling; and physiographic data for the four study basins. (USGS)

HepSim: A repository with predictions for high-energy physics experiments

DOE PAGES

Chekanov, S. V.

2015-02-03

A file repository for calculations of cross sections and kinematic distributions using Monte Carlo generators for high-energy collisions is discussed. The repository is used to facilitate effective preservation and archiving of data from theoretical calculations and for comparisons with experimental data. The HepSim data library is publicly accessible and includes a number of Monte Carlo event samples with Standard Model predictions for current and future experiments. The HepSim project includes a software package to automate the process of downloading and viewing online Monte Carlo event samples. Data streaming over a network for end-user analysis is discussed.

Deployment Area Selection and Land Withdrawal/Acquisition. Chapter 3. M-X/MPS (M-X/Multiple Protective Shelter). Volume 2. Affected Environment.

DTIC Science & Technology

1981-10-02

hydrologic cycle 3-16 3.2.2.1-2 Generalized valley cross section showing basin and range geology 3-19 3.2.2.1-3 Regional groundwater flow in the Great Basin ...vicinity of the Texas/New Mexico study area 3-280 Ix ••,. -%- .7 . ... -., *No. Page 3.3.2.1-3 Major drainage basins and stream gauging stations 3...water-bearing characteristics of hydrogeologic units in the Great Basin 3-20 *3.2.2.1-3 Water availability for Nevada/Utah M-X-affected * valleys 3-29

Velocity, bathymetry, and transverse mixing characteristics of the Ohio River upstream from Cincinnati, Ohio, October 2004-March 2006

USGS Publications Warehouse

Koltun, G.F.; Ostheimer, Chad J.; Griffin, Michael S.

2006-01-01

Velocity, bathymetry, and transverse (cross-channel) mixing characteristics were studied in a 34-mile study reach of the Ohio River extending from the lower pool of the Captain Anthony Meldahl Lock and Dam, near Willow Grove, Ky, to just downstream from the confluence of the Licking and Ohio Rivers, near Newport, Ky. Information gathered in this study ultimately will be used to parameterize hydrodynamic and water-quality models that are being developed for the study reach. Velocity data were measured at an average cross-section spacing of about 2,200 feet by means of boat-mounted acoustic Doppler current profilers (ADCPs). ADCP data were postprocessed to create text files describing the three-dimensional velocity characteristics in each transect. Bathymetry data were measured at an average transect spacing of about 800 feet by means of a boat-mounted single-beam echosounder. Depth information obtained from the echosounder were postprocessed with water-surface slope and elevation information collected during the surveys to compute stream-bed elevations. The bathymetry data were written to text files formatted as a series of space-delimited x-, y-, and z-coordinates. Two separate dye-tracer studies were done on different days in overlapping stream segments in an 18.3-mile section of the study reach to assess transverse mixing characteristics in the Ohio River. Rhodamine WT dye was injected into the river at a constant rate, and concentrations were measured in downstream cross sections, generally spaced 1 to 2 miles apart. The dye was injected near the Kentucky shoreline during the first study and near the Ohio shoreline during the second study. Dye concentrations were measured along transects in the river by means of calibrated fluorometers equipped with flow-through chambers, automatic temperature compensation, and internal data loggers. The use of flow-through chambers permitted water to be pumped continuously out of the river from selected depths and through the fluorometer for measurement as the boat traversed the river. Time-tagged concentration readings were joined with horizontal coordinate data simultaneously captured from a differentially corrected Global Positioning System (GPS) device to create a plain-text, comma-separated variable file containing spatially tagged dye-concentration data. Plots showing the transverse variation in relative dye concentration indicate that, within the stream segments sampled, complete transverse mixing of the dye did not occur. In addition, the highest concentrations of dye tended to be nearest the side of the river from which the dye was injected. Velocity, bathymetry, and dye-concentration data collected during this study are available for Internet download by means of hyperlinks in this report. Data contained in this report were collected between October 2004 and March 2006.

Probe shapes that measure time-averaged streamwise momentum and cross-stream turbulence intensity

NASA Technical Reports Server (NTRS)

Rossow, Vernon J. (Inventor)

1993-01-01

A method and apparatus for directly measuring the time-averaged streamwise momentum in a turbulent stream use a probe which has total head response which varies as the cosine-squared of the angle of incidence. The probe has a nose with a slight indentation on its front face for providing the desired response. The method of making the probe incorporates unique design features. Another probe may be positioned in a side-by-side relationship to the first probe to provide a direct measurement of the total pressure. The difference between the two pressures yields the sum of the squares of the cross-stream components of the turbulence level.

Review of the effects of in-stream pipeline crossing construction on aquatic ecosystems and examination of Canadian methodologies for impact assessment.

PubMed

Lévesque, Lucie M; Dubé, Monique G

2007-09-01

Pipeline crossing construction alters river and stream channels, hence may have detrimental effects on aquatic ecosystems. This review examines the effects of crossing construction on fish and fish habitat in rivers and streams, and recommends an approach to monitoring and assessment of impacts associated with these activities. Pipeline crossing construction is shown to not only compromise the integrity of the physical and chemical nature of fish habitat, but also to affect biological habitat (e.g., benthic invertebrates and invertebrate drift), and fish behavior and physiology. Indicators of effect include: water quality (total suspended solids TSS), physical habitat (substrate particle size, channel morphology), benthic invertebrate community structure and drift (abundance, species composition, diversity, standing crop), and fish behavior and physiology (hierarchy, feeding, respiration rate, loss of equilibrium, blood hematocrit and leukocrit levels, heart rate and stroke volume). The Before-After-Control-Impact (BACI) approach, which is often applied in Environmental Effects Monitoring (EEM), is recommended as a basis for impact assessment, as is consideration of site-specific sensitivities, assessment of significance, and cumulative effects.

Multi-stream portrait of the Cosmic web

NASA Astrophysics Data System (ADS)

Ramachandra, Nesar; Shandarin, Sergei

2016-03-01

We report the results of the first study of the multi-stream environment of dark matter haloes in cosmological N-body simulations in the ΛCDM cosmology. The full dynamical state of dark matter can be described as a three-dimensional sub-manifold in six-dimensional phase space - the dark matter sheet. In our study we use a Lagrangian sub-manifold x = x (q , t) (where x and q are co-moving Eulerian and Lagrangian coordinates respectively), which is dynamically equivalent to the dark matter sheet but is more convenient for numerical analysis. Our major results can be summarized as follows. At the resolution of the simulation, the cosmic web represents a hierarchical structure: each halo is embedded in the filamentary framework of the web predominantly at the filament crossings, and each filament is embedded in the wall like fabric of the web at the wall crossings. Locally, each halo or sub-halo is a peak in the number of streams field. The number of streams in the neighbouring filaments is higher than in the neighbouring walls. The walls are regions where number of streams is equal to three or a few. Voids are uniquely defined by the local condition requiring to be a single-stream flow region.

Acoustic streaming induced by two orthogonal ultrasound standing waves in a microfluidic channel.

PubMed

Doinikov, Alexander A; Thibault, Pierre; Marmottant, Philippe

2018-07-01

A mathematical model is derived for acoustic streaming in a microfluidic channel confined between a solid wall and a rigid reflector. Acoustic streaming is produced by two orthogonal ultrasound standing waves of the same frequency that are created by two pairs of counter-propagating leaky surface waves induced in the solid wall. The magnitudes and phases of the standing waves are assumed to be different. Full analytical solutions are found for the equations of acoustic streaming. The obtained solutions are used in numerical simulations to reveal the structure of the acoustic streaming. It is shown that the interaction of two standing waves leads to the appearance of a cross term in the equations of acoustic streaming. If the phase lag between the standing waves is nonzero, the cross term brings about circular vortices with rotation axes perpendicular to the solid wall of the channel. The vortices make fluid particles rotate and move alternately up and down between the solid wall and the reflector. The obtained results are of immediate interest for acoustomicrofluidic applications such as the ultrasonic micromixing of fluids and the manipulation of microparticles. Copyright © 2018 Elsevier B.V. All rights reserved.

Stream-floodwave propagation through the Great Bend alluvial aquifer, Kansas: Field measurements and numerical simulations

USGS Publications Warehouse

Sophocleous, M.A.

1991-01-01

The hypothesis is explored that groundwater-level rises in the Great Bend Prairie aquifer of Kansas are caused not only by water percolating downward through the soil but also by pressure pulses from stream flooding that propagate in a translatory motion through numerous high hydraulic diffusivity buried channels crossing the Great Bend Prairie aquifer in an approximately west to east direction. To validate this hypothesis, two transects of wells in a north-south and east-west orientation crossing and alongside some paleochannels in the area were instrumented with water-level-recording devices; streamflow data from all area streams were obtained from available stream-gaging stations. A theoretical approach was also developed to conceptualize numerically the stream-aquifer processes. The field data and numerical simulations provided support for the hypothesis. Thus, observation wells located along the shoulders or in between the inferred paleochannels show little or no fluctuations and no correlations with streamflow, whereas wells located along paleochannels show high water-level fluctuations and good correlation with the streamflows of the stream connected to the observation site by means of the paleochannels. The stream-aquifer numerical simulation results demonstrate that the larger the hydraulic diffusivity of the aquifer, the larger the extent of pressure pulse propagation and the faster the propagation speed. The conceptual simulation results indicate that long-distance propagation of stream floodwaves (of the order of tens of kilometers) through the Great Bend aquifer is indeed feasible with plausible stream and aquifer parameters. The sensitivity analysis results indicate that the extent and speed of pulse propagation is more sensitive to variations of stream roughness (Manning's coefficient) and stream channel slope than to any aquifer parameter. ?? 1991.

Experimental investigation of a supersonic swept ramp injector using laser-induced iodine fluorescence

NASA Technical Reports Server (NTRS)

Hartfield, Roy J.; Hollo, Steven D.; Mcdaniel, James C.

1990-01-01

Planar measurements of injectant mole fraction and temperature have been conducted in a nonreacting supersonic combustor configured with underexpanded injection in the base of a swept ramp. The temperature measurements were conducted with a Mach 2 test section inlet in streamwise planes perpendicular to the test section wall on which the ramp was mounted. Injection concentration measurements, conducted in cross flow planes with both Mach 2 and Mach 2.9 free stream conditions, dramatically illustrate the domination of the mixing process by streamwise vorticity generated by the ramp. These measurements, conducted using a nonintrusive optical technique (laser-induced iodine fluorescence), provide an accurate and extensive experimental data base for the validation of computation fluid dynamic codes for the calculation of highly three-dimensional supersonic combustor flow fields.

Specific absorption and backscatter coefficient signatures in southeastern Atlantic coastal waters

NASA Astrophysics Data System (ADS)

Bostater, Charles R., Jr.

1998-12-01

Measurements of natural water samples in the field and laboratory of hyperspectral signatures of total absorption and reflectance were obtained using long pathlength absorption systems (50 cm pathlength). Water was sampled in Indian River Lagoon, Banana River and Port Canaveral, Florida. Stations were also occupied in near coastal waters out to the edge of the Gulf Stream in the vicinity of Kennedy Space Center, Florida and estuarine waters along Port Royal Sound and along the Beaufort River tidal area in South Carolina. The measurements were utilized to calculate natural water specific absorption, total backscatter and specific backscatter optical signatures. The resulting optical cross section signatures suggest different models are needed for the different water types and that the common linear model may only appropriate for coastal and oceanic water types. Mean particle size estimates based on the optical cross section, suggest as expected, that particle size of oceanic particles are smaller than more turbid water types. The data discussed and presented are necessary for remote sensing applications of sensors as well as for development and inversion of remote sensing algorithms.

Nonlinear analysis of generalized cross-field current instability

NASA Technical Reports Server (NTRS)

Yoon, Peter H.; Lui, Anthony T. Y.

1993-01-01

Analysis of the generalized cross-field current instability is carried out in which cross-field drift of both the ions and electrons and their temperatures are permitted to vary in time. The unstable mode under consideration is the electromagnetic generalization of the classical modified-two-stream instability. The generalized instability is made of the modified-two-stream and ion-Weibel modes. The relative importance of the features associated with the ion-Weibel mode and those of the modified-two-stream mode is assessed. Specific applications are made to the Earth's neutral sheet prior to substorm onset and to the Earth's bow shock. The numerical solution indicates that the ion-Weibel mode dominates in the Earth's neutral sheet environment. In contrast, the situation for the bow shock is dominated by the modified-two-stream mode. Notable differences are found between the present calculation and previous results on ion-Weibel mode which restrict the analysis to only parallel propagating waves. However, in the case of Earth's bow shock for which the ion-Weibel mode plays no important role, the inclusion of the electromagnetic ion response is found to differ little from the previous results which treats ions responding only to the electrostatic component of the excited waves.

Mohawk Lake or Mohawk meadow Sedimentary facies and stratigraphy of Quaternary deposits in Mohawk Valley, upper Middle Fork of the Feather River, California

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yount, J.C.; Harwood, D.S.; Bradbury, J.P.

1993-04-01

Mohawk Valley (MV) contain thick, well-exposed sections of Quaternary basin-fill sediments, with abundant interbedded tephra and a diverse assemblage of sedimentary facies. The eastern arm of MV, extending from Clio to Portola, contains as much as 100 m of trough cross-bedded cobble to pebble gravel and planar and trough cross-bedded coarse and medium sand, interpreted as braided stream deposits. Sections exposed in the western arm of MV consist in their lower parts of massive organic-rich silt and clay interbedded with blocky to fissile peat beds up to 1 m thick. Diatom assemblages are dominated by benthic species indicating fresh marshmore » environments with very shallow water depths of one meter or less. Proglacial lacustrine deposits of limited lateral extent are present within the outwash complexes as evidenced by varved fine sand and silt couplets, poorly sorted quartz-rich silt beds containing dropstones, and contorted beds of diamict grading laterally into slump blocks surrounded by wood-bearing silt and silty sand. The Rockland Ash (400 ka) is a prominent marker in the middle or lower part of many sections throughout MV, indicating that at least half of the basin-fill sequence is Late Quaternary in age. A log buried in diamict slumped into a proglacial lake lying approximately 3 km downstream from the Tioga Stage ice termini in Jamison and Gray Eagle Creeks yields an age of 18,715 [+-]235 C[sup 14] years BP. Previous interpretations of MV deposits originating in a large, deep lake with water depths in excess of 150 m are untenable given the sedimentary facies and diatom floras that dominate the valley. Unexhumed valleys such as Sierra Valley to the east and Long Valley to the northwest which contain large meadows traversed by braided streams are probably good analogs for the conditions that existed during the accumulation of the Mohawk Valley deposits.« less

Effect of the implementation of the fluvial performance standard on maintenance of bridges and culverts.

DOT National Transportation Integrated Search

2013-08-01

The objective of this project was to determine what factors influence maintenance cost of Oregon Department of Transportation (ODOT) stream-crossing structures. Data acquired for the project included structure characteristics, stream characteristics,...

Ebb and flow of encroachment by nonnative rainbow trout in a small stream in the southern Appalachian Mountains

USGS Publications Warehouse

Larson, Gary L.; Moore, S.E.

1995-01-01

Brook trout Salvelinus fontinalis is the native salmonid species of streams in the southern Appalachian Mountains. The present distribution of this species, once widespread from headwaters to lower reaches of large streams, is restricted to mostly headwater areas. Changes in the distribution of native brook trout in the presence of' nonnative rainbow trout Oncorhynchus mykiss have been documented in Great Smoky Mountains National Park. When rainbow trout were first found in a tributary (Rock Creek) in the park in 1979, a study was begun to assess changes through time in distribution and abundance of rainbow trout in Rock Creek and to compare the brook trout and rainbow trout associations in Rock Creek with associations found in other park streams. Abundance of brook trout was low in the downstream sections of Rock Creek in 1979a??1993. Brook trout abundance was highest in the steep-gradient, pool-dominated headwater section which was only 2 km from the confluence of Rock Creek and Cosby Creek. Rainbow trout were present in low densities in Rock Creek during the same period. Although rainbow trout were most abundant in the lower stream sections and never found in the headwater section, adult and age-0 rainbow trout were found in the middle section in 1988. Rainbow trout were absent in the middle section in 1991, but one large adult rainbow trout was present in the section in 1992 and 1993. Floods, freshets, and periods of low stream discharge appeared to play an important role in the distribution and population structure of rainbow trout in Rock Creek. The lower portion of Rock Creek was poor trout habitat because the sections were dominated by cobblea??rubble substrate and shallow riffle areas. Stream habitat appeared to be better suited for brook trout than for rainbow trout in the steep-gradient upstream sections which were dominated by boulder-cobble substrate and deep pools. The results of this study suggest that encroachment by rainbow trout can exhibit considerable ebb and flow in steep-gradient tributaries in the park, and they suggest substantial evolutionary adaptation by brook trout to the hydrological conditions in the Rock Creek drainage.

Our Cannibalistic Galaxy

NASA Astrophysics Data System (ADS)

Majewski, S. R.

2004-12-01

It is now evident that our Milky Way has cannibalistic tendencies. Recently found examples of satellite star systems being digested by our galaxy demonstrate that Milky Way-like spiral galaxies continue to grow through the piecemeal accumulation of mass from smaller neighbors, as predicted by Cold Dark Matter (CDM) models of structure formation. Cross-sections of the Milky Way halo reveal it to be networked with long-lived, coherent debris streams of stars and star clusters that attest to its accretive formation. These dynamically cold streams, created from the tidal disruption of satellite star systems, in turn provide useful tools to explore both the nature of Galactic dwarf satellites as well as the the dark matter distribution of the Milky Way; the results of such work, however, yield some unexpected results compared to current CDM models. (Research described has been supported by NASA/JPL, the National Science Foundation, The David and Lucile Packard Foundation, the Research Corporation, and the F.H. Levinson Fund of the Peninsula Community Foundation.)

Flow field measurements for cylindrical configurations in a hypersonic wind tunnel: Windward and leeward flow fields

NASA Technical Reports Server (NTRS)

Bertin, J. J.; Lamb, J. P.; Center, K. R.; Graumann, B. W.

1971-01-01

Windward and leeward measurements were made for a variety of simulated infinite cylinders exposed to hypersonic streams over an angle of attack from 30 deg to 90 deg. For the range of conditions included in the study, the following conclusions are made: (1) Swept cylinder theory provides a reasonable correlation of the measured laminar heat transfer rates from the plane of symmetry. (2) The boundary layer transition criteria in the plane of symmetry are a function of the transverse curvature. (3) Relaminarization of the circumferential boundary layer for a right circular cylinder was observed at the highest Reynolds number tested. (4) The effect of leeside geometry on the average heat transfer rate can be correlated with a single geometric parameter which is dependent on the location of separation. (5) The relationship of leeward heating to angle of attack is virtually linear for each cross section. (6) No systematic effect of free stream Reynolds number was observed.

Regional Curves for Bankfull Channel Characteristics in the Appalachian Plateaus, West Virginia

USGS Publications Warehouse

Messinger, Terence

2009-01-01

Streams in the Appalachian Plateaus Physiographic Province in West Virginia were classified as a single region on the basis of bankfull characteristics. Regression lines for annual peak flow and drainage area measured at streamgages in the study area at recurrence intervals between 1.2 and 1.7 years fell within the 99-percent confidence interval of the regression line for bankfull flow. Channel characteristics were intermediate among those from surrounding states and regions where comparable studies have been done. The stream reaches that were surveyed were selected for apparent stability, and to represent gradients of drainage area, elevation, and mean annual precipitation. Profiles of high-water marks left by bankfull and near-bankfull peaks were surveyed, either as part of slope-area flow measurements at ungaged reaches, or to transfer known flow information to cross sections for gaged reaches. The slope-area measurements made it possible to include ungaged sites in the study, but still relate bankfull dimensions to peak flow and frequency.

CERA-V: Microwave plasma stream source with variable ion energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balmashnov, A.A.

1996-01-01

A microwave plasma stream source with variable ion energy operated under low magnetic field electron cyclotron resonance conditions has been developed. A two mode resonant cavity (TE{sub 111}, {ital E}{sub 010}) was used. It was established that overdense plasma creation (TE{sub 111}) and high energy in-phase space localized electron plasma oscillations ({ital E}{sub 010}) in a decreased magnetic field lead to the potential for ion energy variation from 10 to 300 eV (up to 1 A of ion current, and a plasma cross section of 75 cm{sup 2}, hydrogen) by varying the TE{sub 111}, {ital E}{sub 010} power, the valuemore » of the magnetic field, and pressure. The threshold level of {ital E}{sub 010}-mode power was also determined. An application of this CERA-V source to hydrogenation of semiconductor devices without deterioration of surface layers by ions and fast atoms is under investigation. {copyright} {ital 1996 American Vacuum Society}« less

Importance of the (n,gamma) Cm-247 Evaluation on Neutron Emission in Fast Reactor Fuel Cycle Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benoit Forget; Mehdi Asgari; Rodolfo M. Ferrer

2007-11-01

As part of the GNEP program, it is envisioned to build a fast reactor for the transmutation of minor actinides. The spent nuclear fuel from the current fleet of light water reactors would be recycled, the current baseline is the UREX+1a process, and would act as a feed for the fast reactor. As the fuel is irradiated in a fast reactor a certain quantity of minor actinides would thus build up in the fuel stream creating possible concerns with the neutron emission of these minor actinides for fuel transportation, handling and fabrication. Past neutronic analyses had not tracked minor actinidesmore » above Cm-246 in the transmutation chain, because of the small influence on the overall reactor performance and cycle parameters. However, when trying to quantify the neutron emission from the recycled fuel with high minor actinide content, these higher isotopes play an essential role and should be included in the analysis. In this paper, the influence of tracking these minor actinides on the calculated neutron emission is presented. Also presented is the particular influence of choosing a different evaluated cross section data set to represent the minor actinides above Cm-246. The first representation uses the cross-sections provided by MC2-2 for all isotopes, while the second representation uses infinitely diluted ENDF/BVII.0 cross-sections for Cm-247 to Cf-252 and MC2-2 for all other isotopes.« less

Lateral and vertical channel movement and potential for bed-material movement on the Madison River downstream from Earthquake Lake, Montana

USGS Publications Warehouse

Chase, Katherine J.; McCarthy, Peter M.

2012-01-01

The 1959 Hebgen Lake earthquake caused a massive landslide (Madison Slide) that dammed the Madison River and formed Earthquake Lake. The U.S. Army Corps of Engineers excavated a spillway through the Madison Slide to permit outflow from Earthquake Lake. In June 1970, high streamflows on the Madison River severely eroded the spillway channel and damaged the roadway embankment along U.S. Highway 287 downstream from the Madison Slide. Investigations undertaken following the 1970 flood events concluded that substantial erosion through and downstream from the spillway could be expected for streamflows greater than 3,500 cubic feet per second (ft3/s). Accordingly, the owners of Hebgen Dam, upstream from Earthquake Lake, have tried to manage releases from Hebgen Lake to prevent streamflows from exceeding 3,500 ft3/s measured at the U.S. Geological Survey (USGS) gaging station 0638800 Madison River at Kirby Ranch, near Cameron, Montana. Management of flow releases from Hebgen Lake to avoid exceeding the threshold streamflow at USGS gaging station 06038800 is difficult, and has been questioned for two reasons. First, no road damage was reported downstream from the Earthquake Lake outlet in 1993, 1996, and 1997 when streamflows exceeded the 3,500-ft3/s threshold. Second, the 3,500-ft3/s threshold generally precludes releases of higher flows that could be beneficial to the blue-ribbon trout fishery downstream in the Madison River. In response to concerns about minimizing streamflow downstream from Earthquake Lake and the possible armoring of the spillway, the USGS, in cooperation with the Madison River Fisheries Technical Advisory Committee (MADTAC; Bureau of Land Management; Montana Department of Environmental Quality; Montana Fish, Wildlife and Parks; PPL-Montana; U.S. Department of Agriculture Forest Service - Gallatin National Forest; and U.S. Fish and Wildlife Service), conducted a study to determine movement of the Madison River channel downstream from Earthquake Lake and to investigate the potential for bed material movement along the same reach. The purpose of this report is to present information about the lateral and vertical movement of the Madison River from 1970 to 2006 for a 1-mile reach downstream from Earthquake Lake and for Raynolds Pass Bridge, and to provide an analysis of the potential for bed-material movement so that MADTAC can evaluate the applicability of the previously determined threshold streamflow for initiation of damaging erosion. As part of this study channel cross sections originally surveyed by the USGS in 1971 were resurveyed in 2006. Incremental channel-movement distances were determined by comparing the stream centerlines from 14 aerial photographs taken between 1970 and 2006. Depths of channel incision and aggregation were determined by comparing the 2006 and 1971 cross-section and water-surface data. Particle sizes of bed and bank materials were measured in 2006 and 2008 using the pebble-count method and sieve analyses. A one-dimensional hydraulic-flow model (HEC-RAS) was used to calculate mean boundary-shear stresses for various streamflows; these calculated boundary-shear stresses were compared to calculated critical-shear stresses for the bed materials to determine the potential for bed-material movement. A comparison of lateral channel movement distances with annual peak streamflows shows that streamflows higher than the 3,500-ft3/s threshold were followed by lateral channel movement except from 1991 to 1992 and possibly from 1996 to 1997. However, it was not possible to discern whether the channel moved gradually or suddenly, or in response to one peak flow, to several peak flows, or to sustained flows. The channel moved between 2002 and 2005 even when streamflows were less than the threshold streamflow of 3,500 ft3/s. Comparisons of cross sections and aerial photographs show that the channel has moved laterally and incised and aggraded to varying degrees. The channel has developed meander bends and has incised as much as 5–12 feet (ft) through the upstream part of the Madison Slide (cross sections 1400–800). Near cross section 800, the stream has eroded into the steep right bank between the stream and the road where fill was mechanically placed after 1970. Channel movement also was noted downstream from the Madison Slide. Near Raynolds Pass Bridge, about 3 miles (mi) downstream from Earthquake Lake, elevations across the channel have changed by -1.4 ft to +1.9 ft, but these changes were local in nature and could represent a few rocks or depressions in the bed. Overall, it does not appear that the materials eroded from the Madison Slide are causing aggradation in the subreach near the Raynolds Pass Bridge. Comparisons of critical shear stresses to mean boundary-shear stresses indicate that the D50 particle sizes (median size) along the right side of the bed between cross sections 400 and 500 and along the right side of the bed between cross sections 1300 and 1400 could move at the threshold streamflow. In contrast, most of the D84 particle sizes at those two locations probably will not move at the threshold streamflow. This lack of movement for the larger particles at the threshold streamflow could lead to further armoring of the bed as the D50 and smaller-sized particles are removed from the bed and transported downstream. The Shields parameter values from 0.04 to 0.08 that were used to calculate critical shear stresses could be conservative for a high-gradient stream such as the Madison. A higher, less conservative, Shields parameter would result in higher critical shear stresses, meaning that higher streamflows would be required to move material than those reported herein. In addition, because materials in the channel thalweg are exposed to higher boundary-shear stresses than the materials along the sides of the channel, larger, more erosion-resistant materials likely exist in the deeper parts of the channel where high-flow depths and velocities prevented sediment sampling. Movement of these materials might require higher critical shear stresses than estimated in this report. Characterization of sediment sizes in the center of the stream and observation of bed-material movement for a range of streamflows could provide information to help refine the Shields parameter and critical-shear stress estimates for bed materials in the Madison River downstream from Earthquake Lake. Furthermore, resurveying cross sections and water-surface elevations more frequently (either annually or after high streamflows) could better define the relation between streamflow and lateral and vertical channel movement.

Effects of Hardened Low-Water Crossings on Periphyton and Water Quality in Selected Streams at the Fort Polk Military Reservation, Louisiana, 1998-99 and 2003-04

USGS Publications Warehouse

Bryan, Barbara W.; Bryan, C. Frederick; Lovelace, John K.; Tollett, Roland W.

2007-01-01

In 2003, the U.S. Geological Survey (USGS), at the request of the U.S. Army Joint Readiness Training Center and Fort Polk, began a follow-up study to determine whether installation and modification of hardened low-water crossings had short-term (less than 1 year) or long-term (greater than 1 year) effects on periphyton or water quality in five streams at the Fort Polk Military Reservation, Louisiana. Periphyton data were statistically analyzed for possible differences between samples collected at upstream and downstream sites and before and after low-water crossings were modified on three streams, Big Brushy Creek, Tributary to East Fork of Sixmile Creek, and Tributary to Birds Creek, during 2003?04. Periphyton data also were analyzed for possible differences between samples collected at upstream and downstream sites on two streams, Tributary to Big Brushy Creek and Little Brushy Creek, during 1998?99 and 2003. Variations in periphyton communities could not be conclusively attributed to the modifications. Most of the significant changes in percent frequency of occurrence and average cell density of the 10 most frequently occurring periphyton taxa were increases at downstream sites after the hardened low-water crossing installations or modifications. However, these changes in the periphyton community are not necessarily deleterious to the community structure. Water-quality data collected from upstream and downstream sites on the five streams during 2003?04 were analyzed for possible differences caused by the hardened crossings. Generally, average water-quality values and concentrations were similar at upstream and downstream sites. When average water-quality values or concentrations changed significantly, they almost always changed significantly at both the upstream and downstream sites. It is probable that observed variations in water quality at both upstream and downstream sites are related to differences in rainfall and streamflow during the sample collection periods rather than an effect of the hardened low-water crossing installations or modifications, but additional study is needed.

Cross-regional prediction of long-term trajectory of stream water DOC response to climate change

Treesearch

H. Laudon; J.M. Buttle; S.K. Carey; J.J. McDonnell; K.J. McGuire; J. Seibert; J. Shanley; C. Soulsby; D. Tetzlaff

2012-01-01

There is no scientific consensus about how dissolved organic carbon (DOC) in surface waters is regulated. Here we combine recent literature data from 49 catchments with detailed stream and catchment process information from nine well established research catchments at mid- to high latitudes to examine the question of how climate controls stream water DOC. We show for...

Suspended sediment and turbidity after road construction/improvement and forest harvest in streams of the Trask River Watershed Study, Oregon

Treesearch

Ivan Arismendi; Jeremiah D. Groom; Maryanne Reiter; Sherri L. Johnson; Liz Dent; Mark Meleason; Alba Argerich; Arne E. Skaugset

2017-01-01

Transport of fine-grained sediment from unpaved forest roads into streams is a concern due to the potential negative effects of additional suspended sediment on aquatic ecosystems. Here we compared turbidity and suspended sediment concentration (SSC) dynamics in five nonfish bearing coastal Oregon streams above and below road crossings, during three consecutive time...

Use of plume mapping data to estimate chlorinated solvent mass loss

USGS Publications Warehouse

Barbaro, J.R.; Neupane, P.P.

2006-01-01

Results from a plume mapping study from November 2000 through February 2001 in the sand-and-gravel surficial aquifer at Dover Air Force Base, Delaware, were used to assess the occurrence and extent of chlorinated solvent mass loss by calculating mass fluxes across two transverse cross sections and by observing changes in concentration ratios and mole fractions along a longitudinal cross section through the core of the plume. The plume mapping investigation was conducted to determine the spatial distribution of chlorinated solvents migrating from former waste disposal sites. Vertical contaminant concentration profiles were obtained with a direct-push drill rig and multilevel piezometers. These samples were supplemented with additional ground water samples collected with a minipiezometer from the bed of a perennial stream downgradient of the source areas. Results from the field program show that the plume, consisting mainly of tetrachloroethylene (PCE), trichloroethene (TCE), and cis-1,2-dichloroethene (cis-1,2-DCE), was approximately 670 m in length and 120 m in width, extended across much of the 9- to 18-m thickness of the surficial aquifer, and discharged to the stream in some areas. The analyses of the plume mapping data show that losses of the parent compounds, PCE and TCE, were negligible downgradient of the source. In contrast, losses of cis-1,2-DCE, a daughter compound, were observed in this plume. These losses very likely resulted from biodegradation, but the specific reaction mechanism could not be identified. This study demonstrates that plume mapping data can be used to estimate the occurrence and extent of chlorinated solvent mass loss from biodegradation and assess the effectiveness of natural attenuation as a remedial measure.

Effect of Geometry on Electrokinetic Characterization of Solid Surfaces.

PubMed

Kumar, Abhijeet; Kleinen, Jochen; Venzmer, Joachim; Gambaryan-Roisman, Tatiana

2017-08-01

An analytical approach is presented to describe pressure-driven streaming current (I str ) and streaming potential (U str ) generation in geometrically complex samples, for which the classical Helmholtz-Smoluchowski (H-S) equation is known to be inaccurate. The new approach is valid under the same prerequisite conditions that are used for the development of the H-S equation, that is, the electrical double layers (EDLs) are sufficiently thin and surface conductivity and electroviscous effects are negligible. The analytical methodology is developed using linear velocity profiles to describe liquid flow inside of EDLs and using simplifying approximations to describe macroscopic flow. At first, a general expression is obtained to describe the I str generated in different cross sections of an arbitrarily shaped sample. Thereafter, assuming that the generated U str varies only along the pressure-gradient direction, an expression describing the variation of generated U str along the sample length is obtained. These expressions describing I str and U str generation constitute the theoretical foundation of this work, which is first applied to a set of three nonuniform cross-sectional capillaries and thereafter to a square array of cylindrical fibers (model porous media) for both parallel and transverse fiber orientation cases. Although analytical solutions cannot be obtained for real porous substrates because of their random structure, the new theory provides useful insights into the effect of important factors such as fiber orientation, sample porosity, and sample dimensions. The solutions obtained for the model porous media are used to device strategies for more accurate zeta potential determination of porous fiber plugs. The new approach could be thus useful in resolving the long-standing problem of sample geometry dependence of zeta potential measurements.

Wind tunnel

NASA Technical Reports Server (NTRS)

Wilson, E. M. (Inventor)

1969-01-01

A supersonic wind wind tunnel is described for testing several air foils mounted in a row. A test section of a wind tunnel contains means for mounting air foil sections in a row, means for rotating each section about an axis so that the angle of attack of each section changes with the other sections, and means for rotating the row with respect to the air stream so that the row forms an oblique angle with the air stream.

Regular and transitory showers of comet C/1979 Y1 (Bradfield)

NASA Astrophysics Data System (ADS)

Hajduková, M.; Neslušan, L.

2017-09-01

Aims: We intend to map the whole meteor complex of the long-period comet C/1979 Y1 (Bradfield), which is a proposed parent body of the July Pegasids, No. 175 in the list of meteor showers established by the Meteor Data Center (MDC) of the International Astronomical Union (IAU). Methods: For five perihelion passages of the parent comet in the past, we model associated theoretical stream, its parts, each consisting of 10 000 test particles, and follow the dynamical evolution of these parts up to the present. Subsequently, we analyze the mean orbital characteristics of those particles of the parts that approach the Earth's orbit and, thus, create a shower or showers. The showers are compared with their observed counterparts separated from photographic, radio, and several video databases. Results: The modeled stream of C/1979 Y1 approaches the Earth's orbit in two filaments that correspond to two regular (annual) showers. We confirm the generic relationship between the studied parent comet and 175 July Pegasids. The other predicted shower is a daytime shower with the mean radiant situated symmetrically to the July Pegasids with respect to the apex of the Earth's motion. This shower is not in the IAU MDC list, but we separated it from the Cameras-for-Allsky-Meteor-Surveillance (CAMS) and SonotaCo video data as a new shower. We suggest naming it α-Microscopiids. The stronger influence of the Poynting-Robertson drag deflects the stream away from the Earth's orbit in those sections that correspond to the July Pegasids and the predicted daytime shower, but it makes the stream cross the Earth's orbit in other sections. Corresponding showers are, however, only expected to survive during a limited period and to consist of particles of sizes in a narrow interval. We identified one of these "transitory" filaments to the 104 γ-Bootids in the IAU MDC list of meteor showers.

Differential modulation of auditory responses to attended and unattended speech in different listening conditions

PubMed Central

Kong, Ying-Yee; Mullangi, Ala; Ding, Nai

2014-01-01

This study investigates how top-down attention modulates neural tracking of the speech envelope in different listening conditions. In the quiet conditions, a single speech stream was presented and the subjects paid attention to the speech stream (active listening) or watched a silent movie instead (passive listening). In the competing speaker (CS) conditions, two speakers of opposite genders were presented diotically. Ongoing electroencephalographic (EEG) responses were measured in each condition and cross-correlated with the speech envelope of each speaker at different time lags. In quiet, active and passive listening resulted in similar neural responses to the speech envelope. In the CS conditions, however, the shape of the cross-correlation function was remarkably different between the attended and unattended speech. The cross-correlation with the attended speech showed stronger N1 and P2 responses but a weaker P1 response compared with the cross-correlation with the unattended speech. Furthermore, the N1 response to the attended speech in the CS condition was enhanced and delayed compared with the active listening condition in quiet, while the P2 response to the unattended speaker in the CS condition was attenuated compared with the passive listening in quiet. Taken together, these results demonstrate that top-down attention differentially modulates envelope-tracking neural activity at different time lags and suggest that top-down attention can both enhance the neural responses to the attended sound stream and suppress the responses to the unattended sound stream. PMID:25124153

Suspended sediment and turbidity after road construction/improvement and forest harvest in streams of the Trask River Watershed Study, Oregon

NASA Astrophysics Data System (ADS)

Arismendi, Ivan; Groom, Jeremiah D.; Reiter, Maryanne; Johnson, Sherri L.; Dent, Liz; Meleason, Mark; Argerich, Alba; Skaugset, Arne E.

2017-08-01

Transport of fine-grained sediment from unpaved forest roads into streams is a concern due to the potential negative effects of additional suspended sediment on aquatic ecosystems. Here we compared turbidity and suspended sediment concentration (SSC) dynamics in five nonfish bearing coastal Oregon streams above and below road crossings, during three consecutive time periods ("before", "after road construction/improvement", and "after forest harvest and hauling"). We hypothesized that the combined effects of road construction/improvement and the hauling following forest harvest would increase turbidity and SSC in these streams. We tested whether the differences between paired samples from above and below road crossing exceeded various biological thresholds, using literature values of biological responses to increases in SSC and turbidity. Overall, we found minimal increases of both turbidity and SSC after road improvement, forest harvest, and hauling. Because flow is often used as a surrogate for turbidity or SSC we examined these relationships using data from locations above road crossings that were unaffected by roads or forest harvest and hauling. In addition, we examined the association between turbidity and SSC for these background locations. We found a positive, but in some cases weak association between flow and turbidity, and between flow and SSC; the relationship between turbidity and SSC was more robust, but also inconsistent among sites over time. In these low order streams, the concentrations and transport of suspended sediment seems to be highly influenced by the variability of local conditions. Our study provides an expanded understanding of current forest road management practice effects on fine-grained sediment in streams and introduces alternative metrics using multiple thresholds to evaluate potential indicators of biological relevance.

Evaluating the use of drone photogrammetry for measurement of stream channel morphology and response to high flow events

NASA Astrophysics Data System (ADS)

Price, Katie; Ballow, William

2015-04-01

Traditional high-precision survey methods for stream channel measurement are labor-intensive and require wadeability or boat access to streams. These conditions limit the number of sites researchers are able to study and generally prohibit the possibility of repeat channel surveys to evaluate short-term fluctuations in channel morphology. In recent years, unmanned aerial vehicles (drones) equipped with photo and video capabilities have become widely available and affordable. Concurrently, developments in photogrammetric software offer unprecedented mapping and 3D rendering capabilities of drone-captured photography. In this study, we evaluate the potential use of drone-mounted cameras for detailed stream channel morphometric analysis. We used a relatively low-cost drone (DJI Phantom 2+ Vision) and commercially available, user friendly software (Agisoft Photscan) for photogrammetric analysis of drone-captured stream channel photography. Our test study was conducted on Proctor Creek, a highly responsive urban stream in Atlanta, Georgia, within the crystalline Piedmont region of the southeastern United States. As a baseline, we performed traditional high-precision survey methods to collect morphological measurements (e.g., bankfull and wetted width, bankfull and wetted thalweg depth) at 11 evenly-spaced transects, following USGS protocols along reaches of 20 times average channel width. We additionally used the drone to capture 200+ photos along the same reaches, concurrent with the channel survey. Using the photogrammetry software, we generated georeferenced 3D models of the stream channel, from which morphological measurements were derived from the 11 transects and compared with measurements from the traditional survey method. We additionally explored possibilities for novel morphometric characterization available from the continuous 3D surface, as an improvement on the limited number of detailed cross-sections available from standard methods. These results showed great promise for the drone photogrammetry methods, which encouraged the exploration of the possibility of repeat aerial surveys to evaluate channel response to high flow events. Repeat drone surveys were performed following a sequence of high-flow events in Proctor Creek to evaluate the possibility of using these methods for assessment of stream channel response to flooding.

Dynamical Evolution of Meteoroid Streams, Developments Over the Last 30 Years

NASA Technical Reports Server (NTRS)

Williams, I. P.

2011-01-01

As soon as reliable methods for observationally determining the heliocentric orbits of meteoroids and hence the mean orbit of a meteoroid stream in the 1950s and 60s, astronomers strived to investigate the evolution of the orbit under the effects of gravitational perturbations from the planets. At first, the limitations in the capabilities of computers, both in terms of speed and memory, placed severe restrictions on what was possible to do. As a consequence, secular perturbation methods, where the perturbations are averaged over one orbit became the norm. The most popular of these is the Halphen- Goryachev method which was used extensively until the early 1980s. The main disadvantage of these methods lies in the fact that close encounter can be missed, however they remain useful for performing very long-term integrations. Direct integration methods determine the effects of the perturbing forces at many points on an orbit. This give a better picture of the orbital evolution of an individual meteoroid, but many meteoroids have to be integrated in order to obtain a realistic picture of the evolution of a meteoroid stream. The notion of generating a family of hypothetical meteoroids to represent a stream and directly integrate the motion of each was probably first used by Williams Murray & Hughes (1979), to investigate the Quadrantids. Because of computing limitations, only 10 test meteoroids were used. Only two years later, Hughes et. al. (1981) had increased the number of particles 20-fold to 200 while after a further year, Fox Williams and Hughes used 500 000 test meteoroids to model the Geminid stream. With such a number of meteoroids it was possible for the first time to produce a realistic cross-section of the stream on the ecliptic. From that point on there has been a continued increase in the number of meteoroids, the length of time over which integration is carried out and the frequency with which results can be plotted so that it is now possible to produce moving images of the stream. As a consequence, over recent years, emphasis has moved to considering stream formation and the role fragmentation plays in this.

No Snow No Flow: How Montane Stream Networks Respond to Drought

NASA Astrophysics Data System (ADS)

Grant, G.; Nolin, A. W.; Selker, J. S.; Lewis, S.; Hempel, L. A.; Jefferson, A.; Walter, C.; Roques, C.

2015-12-01

Hydrologic extremes, such as drought, offer an exceptional opportunity to explore how runoff generation mechanisms and stream networks respond to changing precipitation regimes. The winter of 2014-2015 was the warmest on record in western Oregon, US, with record low snowpacks, and was followed by an anomalously warm, dry spring, resulting in historically low streamflows. But a year like 2015 is more than an outlier meteorological year. It provides a unique opportunity to test fundamental hypotheses for how montane hydrologic systems will respond to anticipated changes in amount and timing of recharge. In particular, the volcanic Cascade Mountains represent a "landscape laboratory" comprised of two distinct runoff regimes: the surface-flow dominated Western Cascade watersheds, with flashy streamflow regimes, rapid baseflow recession, and very low summer flows; and (b) the spring-fed High Cascade watersheds, with a slow-responding streamflow regime, and a long and sustained baseflow recession that maintains late summer streamflow through deep-groundwater contributions to high volume, coldwater springs. We hypothesize that stream network response to the extremely low snowpack and recharge varies sharply in these two regions. In surface flow dominated streams, the location of channel heads can migrate downstream, contracting the network longitudinally; wetted channel width and depth contract laterally as summer recession proceeds and flows diminish. In contrast, in spring-fed streams, channel heads "jump" to the next downstream spring when upper basin spring flow diminishes to zero. Downstream of flowing springs, wetted channel width and depth contract laterally as flows recede. To test these hypotheses, we conducted a field campaign to measure changing discharge, hydraulic geometry, and channel head location in both types of watersheds throughout the summer and early fall. Multiple cross-section sites were established on 6 streams representing both flow regime types on either side of the Cascade crest. We also took Isotopic water samples to determine recharge elevations of receding streams. Taken together these measurements reveal the processes by which drainage networks contract as flows diminish - a fundamental property of montane stream systems both now and in the future.

40 CFR 63.8020 - What requirements apply to my wastewater streams?

Code of Federal Regulations, 2010 CFR

2010-07-01

... wastewater streams? 63.8020 Section 63.8020 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... apply to my wastewater streams? (a) You must meet each requirement in Table 4 to this subpart that applies to your wastewater streams, and you must meet each applicable requirement specified in § 63.8000...

40 CFR 63.8020 - What requirements apply to my wastewater streams?

Code of Federal Regulations, 2013 CFR

2013-07-01

... wastewater streams? 63.8020 Section 63.8020 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... apply to my wastewater streams? (a) You must meet each requirement in Table 4 to this subpart that applies to your wastewater streams, and you must meet each applicable requirement specified in § 63.8000...

40 CFR 63.8020 - What requirements apply to my wastewater streams?

Code of Federal Regulations, 2011 CFR

2011-07-01

... wastewater streams? 63.8020 Section 63.8020 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... apply to my wastewater streams? (a) You must meet each requirement in Table 4 to this subpart that applies to your wastewater streams, and you must meet each applicable requirement specified in § 63.8000...

40 CFR 63.8020 - What requirements apply to my wastewater streams?

Code of Federal Regulations, 2012 CFR

2012-07-01

... wastewater streams? 63.8020 Section 63.8020 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... apply to my wastewater streams? (a) You must meet each requirement in Table 4 to this subpart that applies to your wastewater streams, and you must meet each applicable requirement specified in § 63.8000...

40 CFR 63.8020 - What requirements apply to my wastewater streams?

Code of Federal Regulations, 2014 CFR

2014-07-01

... wastewater streams? 63.8020 Section 63.8020 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... apply to my wastewater streams? (a) You must meet each requirement in Table 4 to this subpart that applies to your wastewater streams, and you must meet each applicable requirement specified in § 63.8000...

Estimation and modeling of electrofishing capture efficiency for fishes in wadeable warmwater streams

USGS Publications Warehouse

Price, A.; Peterson, James T.

2010-01-01

Stream fish managers often use fish sample data to inform management decisions affecting fish populations. Fish sample data, however, can be biased by the same factors affecting fish populations. To minimize the effect of sample biases on decision making, biologists need information on the effectiveness of fish sampling methods. We evaluated single-pass backpack electrofishing and seining combined with electrofishing by following a dual-gear, mark–recapture approach in 61 blocknetted sample units within first- to third-order streams. We also estimated fish movement out of unblocked units during sampling. Capture efficiency and fish abundances were modeled for 50 fish species by use of conditional multinomial capture–recapture models. The best-approximating models indicated that capture efficiencies were generally low and differed among species groups based on family or genus. Efficiencies of single-pass electrofishing and seining combined with electrofishing were greatest for Catostomidae and lowest for Ictaluridae. Fish body length and stream habitat characteristics (mean cross-sectional area, wood density, mean current velocity, and turbidity) also were related to capture efficiency of both methods, but the effects differed among species groups. We estimated that, on average, 23% of fish left the unblocked sample units, but net movement varied among species. Our results suggest that (1) common warmwater stream fish sampling methods have low capture efficiency and (2) failure to adjust for incomplete capture may bias estimates of fish abundance. We suggest that managers minimize bias from incomplete capture by adjusting data for site- and species-specific capture efficiency and by choosing sampling gear that provide estimates with minimal bias and variance. Furthermore, if block nets are not used, we recommend that managers adjust the data based on unconditional capture efficiency.

Backwater development by woody debris

NASA Astrophysics Data System (ADS)

Geertsema, Tjitske; Torfs, Paul; Teuling, Ryan; Hoitink, Ton

2017-04-01

Placement of woody debris is a common method for increasing ecological values in river and stream restoration, and is thus widely used in natural environments. Water managers, however, are afraid to introduce wood in channels draining agricultural and urban areas. Upstream, it may create backwater, depending on hydrodynamic characteristics including the obstruction ratio, the Froude number and the surface level gradient. Patches of wood may trigger or counter morphological activity, both laterally, through bank erosion and protection, and vertically, with pool and riffle formation. Also, a permeable construction composed of wood will weather over time. Both morphodynamic activity and weathering cause backwater effects to change in time. The purpose of this study is to quantify the time development of backwater effects caused by woody debris. Hourly water levels gauged upstream and downstream of patches and discharge are collected for five streams in the Netherlands. The water level drop over the woody debris patch relates to discharge in the streams. This relation is characterized by an increasing water level difference for an increasing discharge, up to a maximum. If the discharge increases beyond this level, the water level difference reduces to the value that may represent the situation without woody debris. This reduction depends primarily on the obstruction ratio of the woody debris in the channel cross-section. Morphologic adjustments in the stream and reorientation of the woody material reduce the water level drop over the patches in time. Our results demonstrate that backwater effects can be reduced by optimizing the location where woody debris is placed and manipulating the obstruction ratio. Current efforts are focussed on representing woody debris in a one-dimensional numerical model, aiming to obtain a generic tool to achieve a stream design with woody debris that minimizes backwater.

Radionuclides deposition and fine sediment transport in a forested watershed, central Japan

NASA Astrophysics Data System (ADS)

Nam, S.; Gomi, T.; Kato, H.; Tesfaye, T.; Onda, Y.

2011-12-01

We investigated radionuclides deposition and fine sediment transport in a 13 ha headwater watershed, Tochigi prefecture, located in 98.94 km north of Tokyo. The study site was within Karasawa experimental forest, Tokyo University of Agriculture and Technology. We conducted fingerprinting approach, based on the activities of fallout radionuclides, including caesium-134 (Cs-134) caesium-137 (Cs-137) and excess lead-210 (Pb-210ex). For indentifying specific sources of fine sediment, we sampled tree, soil on forested floor, soil on logging road surface, stream bed and stream banks. We investigated the radionuclides (i.e., as Cs-134, Cs-137 and Pb-210ex) deposition on tree after accident of nuclear power plants on March 11, 2011. We sampled fruits, leaves, branches, stems, barks on Japanese cedar (Sugi) and Japanese cypress (Hinoki). To analyze the samples, gammaray spectrometry was performed at a laboratory at the University of Tsukuba (Tsukuba City, Japan) using n-type coaxial low-energy HPGe gamma detectors (EGC-200-R and EGC25-195-R of EURYSIS Co., Lingolsheim, France) coupled with a multichannel analyzer. We also collected soil samples under the forest canopy in various soil depths from 2, 5, 10, 20, 30 cm along transect of hillslopes. Samples at forest road were collected road segments crossing on the middle section of monitoring watersheds. Fine sediment transport in the streams were collected at the outlet of 13 ha watersheds using integrated suspended sediment samplers. This study indicates the some portion of radio nuclide potentially remained on the tree surface. Part of the deposited radionuclides attached to soil particles and transported to the streams. Most of the fine sediment can be transported on road surface and/or near stream side (riparian zones).

Backwater at bridges and densely wooded flood plains, west fork Amite River near Liberty, Mississippi

USGS Publications Warehouse

Colson, B.E.; Ming, C.O.; Arcement, George J.

1979-01-01

Floodflow data that will provide a base for evaluating digital models relating to open-channel flow were obtained at 22 sites on streams in Alabama, Louisiana, and Mississippi. Thirty-five floods were measured. Analysis of the data indicated methods currently in use would be inaccurate where densely vegetated flood plains are crossed by highway embankments and single-opening bridges. This atlas presents flood information at the site on West Fork Amite River near Liberty, MS. Water depths , velocities, and discharges through bridge openings on West Fork Amite River near Liberty, MS for floods of December 6, 1971 , and March 25, 1973, are shown, together with peak water-surface elevations along embankments and along cross sections. Manning 's roughness coefficient values in different parts of the flood plain are shown on maps, and flood-frequency relations are shown on a graph. (USGS).

Network Structure as a Modulator of Disturbance Impacts in Streams

NASA Astrophysics Data System (ADS)

Warner, S.; Tullos, D. D.

2017-12-01

This study examines how river network structure affects the propagation of geomorphic and anthropogenic disturbances through streams. Geomorphic processes such as debris flows can alter channel morphology and modify habitat for aquatic biota. Anthropogenic disturbances such as road construction can interact with the geomorphology and hydrology of forested watersheds to change sediment and water inputs to streams. It was hypothesized that the network structure of streams within forested watersheds would influence the location and magnitude of the impacts of debris flows and road construction on sediment size and channel width. Longitudinal surveys were conducted every 50 meters for 11 kilometers of third-to-fifth order streams in the H.J. Andrews Experimental Forest in the Western Cascade Range of Oregon. Particle counts and channel geometry measurements were collected to characterize the geomorphic impacts of road crossings and debris flows as disturbances. Sediment size distributions and width measurements were plotted against the distance of survey locations through the network to identify variations in longitudinal trends of channel characteristics. Thresholds for the background variation in sediment size and channel width, based on the standard deviations of sample points, were developed for sampled stream segments characterized by location as well as geomorphic and land use history. Survey locations were classified as "disturbed" when they deviated beyond the reference thresholds in expected sediment sizes and channel widths, as well as flow-connected proximity to debris flows and road crossings. River network structure was quantified by drainage density and centrality of nodes upstream of survey locations. Drainage density and node centrality were compared between survey locations with similar channel characteristic classifications. Cluster analysis was used to assess the significance of survey location, proximity of survey location to debris flows and road crossings, drainage density and node centrality in predicting sediment size and channel width classifications for locations within the watershed. Results contribute to the understanding of susceptibility and responses of streams supporting critical habitat for aquatic species to debris flows and forest road disturbances.

Investigation of Pier Scour in Coarse-Bed Streams in Montana, 2001 through 2007

DOT National Transportation Integrated Search

2011-01-01

Determination of pier-scour potential is an important consideration in the hydraulic analysis and design of highway bridges that cross streams, rivers, and other waterways in the United States. A primary goal of ongoing research in the field of bridg...

Drag Corrections in High-Speed Wind Tunnels

NASA Technical Reports Server (NTRS)

Ludwieg, H.

1947-01-01

In the vicinity of a body in a wind tunnel the displacement effect of the wake, due to the finite dimensions of the stream, produces a pressure gradient which evokes a change of drag. In incompressible flow this change of drag is so small, in general, that one does not have to take it into account in wind-tunnel measurements; however, in compressible flow it beoomes considerably larger, so that a correction factor is necessary for measured values. Correction factors for a closed tunnel and an open jet with circular cross sections are calculated and compared with the drag - corrections already bown for high-speed tunnnels.

Hydraulic geometry and streamflow of channels in the Piceance Basin, Rio Blanco and Garfield counties, Colorado

USGS Publications Warehouse

Elliott, J.G.; Cartier, K.D.

1986-01-01

The influence of streamflow and basin characteristics on channel geometry was investigated at 18 perennial and ephemeral stream reaches in the Piceance basin of northwestern Colorado. Results of stepwise multiple regression analyses indicated that the variabilities of mean bankfull depth (D) and bankfull cross-sectional flow area (Af) were predominantly a function of bankfull discharge (QB), and that most of the variability in channel slopes (S) could be explained by drainage area (DA). None of the independent variables selected for the study could account for a large part of the variability in bankfull channel width (W). (USGS)

Deployment Area Selection and Land Withdrawal/Acquisition. Chapter 3. M-X/MPS (M-X/Multiple Protective Shelter). Volume 1. Affected Environment.

DTIC Science & Technology

1981-10-02

3.2.2.1-1 The hydrologic cycle 3-16 3.2.2. 1-2 Generalized valley cross section showing basin and range geology 3-19 3.2.2.1-3 Regional groundwater flow...in the Great Basin 3-25 3.2.2.3-1 Nonattainment areas, mandatory Class I areas, and areas recommended for redesignation to Class I in the Nevada/Utah...study area 3-2, I) I x ,. • . . .. . . - +. ~ . • .. _. .+ " .-. ’. - ’ _. No. Page ". :i.’I 3.3.2.1-3 Major drainage basins and stream gauging

Computing discharge using the index velocity method

USGS Publications Warehouse

Levesque, Victor A.; Oberg, Kevin A.

2012-01-01

Application of the index velocity method for computing continuous records of discharge has become increasingly common, especially since the introduction of low-cost acoustic Doppler velocity meters (ADVMs) in 1997. Presently (2011), the index velocity method is being used to compute discharge records for approximately 470 gaging stations operated and maintained by the U.S. Geological Survey. The purpose of this report is to document and describe techniques for computing discharge records using the index velocity method. Computing discharge using the index velocity method differs from the traditional stage-discharge method by separating velocity and area into two ratings—the index velocity rating and the stage-area rating. The outputs from each of these ratings, mean channel velocity (V) and cross-sectional area (A), are then multiplied together to compute a discharge. For the index velocity method, V is a function of such parameters as streamwise velocity, stage, cross-stream velocity, and velocity head, and A is a function of stage and cross-section shape. The index velocity method can be used at locations where stage-discharge methods are used, but it is especially appropriate when more than one specific discharge can be measured for a specific stage. After the ADVM is selected, installed, and configured, the stage-area rating and the index velocity rating must be developed. A standard cross section is identified and surveyed in order to develop the stage-area rating. The standard cross section should be surveyed every year for the first 3 years of operation and thereafter at a lesser frequency, depending on the susceptibility of the cross section to change. Periodic measurements of discharge are used to calibrate and validate the index rating for the range of conditions experienced at the gaging station. Data from discharge measurements, ADVMs, and stage sensors are compiled for index-rating analysis. Index ratings are developed by means of regression techniques in which the mean cross-sectional velocity for the standard section is related to the measured index velocity. Most ratings are simple-linear regressions, but more complex ratings may be necessary in some cases. Once the rating is established, validation measurements should be made periodically. Over time, validation measurements may provide additional definition to the rating or result in the creation of a new rating. The computation of discharge is the last step in the index velocity method, and in some ways it is the most straight-forward step. This step differs little from the steps used to compute discharge records for stage-discharge gaging stations. The ratings are entered into database software used for records computation, and continuous records of discharge are computed.

Analysis and classification of topographic flow steering and inferred geomorphic processes as a function of discharge in a mountain river

NASA Astrophysics Data System (ADS)

Gore, J.; Pasternack, G. B.; Wiener, J.

2016-12-01

Process-based river classification tends to be done at reach to catchment scales assuming channels are uniform and thus differentiated by the simple specific stream power metric. In fact, mountain rivers are highly variable at subreach scales to the point that local topographic steering may be the dominant control on geomorphic processes. This study presents a new framework for characterizing how stage-dependent topographic steering varies continuously down a river, leading to a classification of subreach landforms on the basis of the geomorphic mechanism of flow convergence routing. The two remote mountain river segments were located in the 3480-km2 Yuba River, with the upper South Yuba having a substantial sediment supply from legacy hydraulic gold mining and the mainstem Yuba downstream of New Bullards Bar Dam having a restricted sediment supply. Meter-scale DEMs were produced for both cases using airborne LiDAR and survey data. DEMs were slope detrended to focus the analysis on cross-sectional variability. DEMs were then heavily smoothed to allow for automated tracing of the valley centerline, and then cross-sectional rectangles were spaced every 5 m. The average width (W) and detrended bed elevation (Z) of the wetted area was computed from the DEM for each raster for 6-7 different river stages. Both width and cross-sectionally averaged bed elevation were standardized. The product of these two variables was computed as a measure of cross-sectional area, and is termed the geomorphic covariance (Czw) series when plotted along each river corridor. Cwz was then used to classify each cross-section as one of five distinct landform types: nozzle, wide bar, normal channel, constricted pool, and oversized pool- with this classification varying with discharge such that a section could, for example, function as a nozzle during low flow but an oversized pool at high flow, or any other combination. Longitudinal profiles of bed elevation, width, covariance, and landform type were analyzed for their stage-dependent patterns to understand their geomorphic significance and to contrast the two rivers. This new method may be the first example of a hierarchical, process-based classification at the subreach scale in which one mechanism is assessed for how it varies not only in space, but as a function of discharge.

Three-dimensional structure of dilute pyroclastic density currents

NASA Astrophysics Data System (ADS)

Andrews, B. J.

2013-12-01

Unconfined experimental density currents dynamically similar to pyroclastic density currents (PDCs) suggest that cross-stream motions of the currents and air entrainment through currents' lateral margins strongly affects PDC behavior. Experiments are conducted within an air-filled tank 8.5 m long by 6.1 m wide by 2.6 m tall. Currents are generated by feeding heated powders down a chute into the tank at controlled rates to form dilute, particle-laden, turbulent gravity currents that are fed for 30 to 600 seconds. Powders include 5 μm aluminum oxide, 25 μm talc, 27 μm walnut, 76 μm glass beads and mixtures thereof. Experiments are scaled such that Froude, densimetric and thermal Richardson, particle Stokes and Settling numbers, and thermal to kinetic energy densities are all in agreement with dilute PDCs; experiments have lower Reynolds numbers that natural currents, but the experiments are fully turbulent, thus the large scale structures should be similar. The experiments are illuminated with 3 orthogonal laser sheets (650, 532, and 450 nm wavelengths) and recorded with an array of HD video cameras and a high speed camera (up to 3000 fps); this system provides synchronous observation of a vertical streamwise and cross-stream planes, and a horizontal plane. Ambient temperature currents tend to spread out radially from the source and have long run out distances, whereas warmer currents tend to focus along narrow sectors and have shorter run outs. In addition, when warm currents lift off to form buoyant plumes, lateral spreading ceases. The behavior of short duration currents are dominated by the current head; as eruption duration increases, current transport direction tends to oscillate back and forth (this is particularly true for ambient temperature currents). Turbulent structures in the horizontal plane show air entrainment and advection downstream. Eddies illuminated by the vertical cross-stream laser sheet often show vigorous mixing along the current margins, particularly after the current head has passed. In some currents, the head can persist as a large, vertically oriented vortex long after the bulk of the current has lifted off to form a coignimbrite plume. These unconfined experiments show that three-dimensional structures can affect PDC behavior and suggest that our typical cross-sectional or 'cartoon' understanding of PDCs misses what may be very important parts of PDC dynamics.

Mapping longitudinal stream connectivity in the North St. Vrain Creek watershed of Colorado

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wohl, Ellen; Rathburn, Sara; Chignell, Stephen

We use reach-scale stream gradient as an indicator of longitudinal connectivity for water, sediment, and organic matter in a mountainous watershed in Colorado. Stream reaches with the highest gradient tend to have narrow valley bottoms with limited storage space and attenuation of downstream fluxes, whereas stream reaches with progressively lower gradients have progressively more storage and greater attenuation. We compared the distribution of stream gradient to stream-reach connectivity rankings that incorporated multiple potential control variables, including lithology, upland vegetation, hydroclimatology, road crossings, and flow diversions. We then assessed connectivity rankings using different weighting schemes against stream gradient and against field-basedmore » understanding of relative connectivity within the watershed. Here, we conclude that stream gradient, which is simple to map using publicly available data and digital elevation models, is the most robust indicator of relative longitudinal connectivity within the river network.« less

Mapping longitudinal stream connectivity in the North St. Vrain Creek watershed of Colorado

DOE PAGES

Wohl, Ellen; Rathburn, Sara; Chignell, Stephen; ...

2016-05-06

We use reach-scale stream gradient as an indicator of longitudinal connectivity for water, sediment, and organic matter in a mountainous watershed in Colorado. Stream reaches with the highest gradient tend to have narrow valley bottoms with limited storage space and attenuation of downstream fluxes, whereas stream reaches with progressively lower gradients have progressively more storage and greater attenuation. We compared the distribution of stream gradient to stream-reach connectivity rankings that incorporated multiple potential control variables, including lithology, upland vegetation, hydroclimatology, road crossings, and flow diversions. We then assessed connectivity rankings using different weighting schemes against stream gradient and against field-basedmore » understanding of relative connectivity within the watershed. Here, we conclude that stream gradient, which is simple to map using publicly available data and digital elevation models, is the most robust indicator of relative longitudinal connectivity within the river network.« less

Investigation into aerodynamic and heat transfer of annular channel with inner and outer surface of the shape truncated cone and swirling fluid flow

NASA Astrophysics Data System (ADS)

Leukhin, Yu L.; Pankratov, E. V.; Karpov, S. V.

2017-11-01

We have carried out Investigation into aerodynamic and convective heat transfer of the annular channel. Inner or outer surface of annular channel has shape of blunt-nosed cone tapering to outlet end. Truncated cone connects to a cyclone swirling flow generator. Asymmetric and unsteady flow from the swirling generator in the shape of periodic process gives rise to the formation of secondary flows of the type Taylor-Görtler vortices. These vortices occupy the whole space of the annular channel, with the axes, which coincide with the motion direction of the major stream. Contraction of cross-sectional area of channel (in both cases 52%) causes a marked increase in total velocity of flow, primarily due to its axial component and promotes a more intensive vortex generation. Vortex structures have a significant influence on both average heat transfer and surface distribution. At cross-sections of the annular channel we observe similarity of curves describing distribution of total velocity about wall and heat flux density on the surface. The coordinates of maximum and minimum values of velocity and heat flux coincide. At the average cross-section channel of maximum value of heat transfer is greater than minimum of about by a factor of 2.7 times for outer heat transfer surface and about by a factor of 1.7 times for inner heat transfer surface. Taper channel has a much higher influence on heat transfer of the inner surface than the outer surface and manifests itself at lower values of dimensionless axial coordinate. For the investigated taper cone geometry of the annular channel the heat transfer coefficient of inner surface increases at the outlet section and exceeds value in comparison with straight-line section by 91 … 98%. Heat transfer of the outer cylinder in the same section increases only by 5 … 11%. The increase in average heat transfer over the surfaces is 36% and 4% respectively.

Northern/Intermountain Regions' fish habitat inventory: Grazed, rested, and ungrazed reference stream reaches, Silver King Creek, California

Treesearch

C. Kerry Overton; Gwynne L. Chandler; Janice A. Pisano

1994-01-01

Stream reaches that have been rested from livestock grazing appear to have stable banks and more bank undercuts than grazed stream sections. Ungrazed reference streams that are similar in parent geology, precipitation, channel type, habitat types, drainage area, and stream width had greater bank stability values and lower width-todepth ratios than those of grazed and...

Clark Canyon (Mono County) Riparian Demonstration Area

Treesearch

John W. Key; Mark A. Gish

1989-01-01

The Clark Canyon riparian demonstration area was established in 1984 within the East Walker River subbasin of Mono County, California. Destabilization of the meadow sections of the stream and the upper stream reaches contributed to an increase of suspended sediments, turbidity, and stream channel widening in the lower stream reaches where a viable population of rainbow...

Reconciling Time, Space and Function: A New Dorsal-Ventral Stream Model of Sentence Comprehension

ERIC Educational Resources Information Center

Bornkessel-Schlesewsky, Ina; Schlesewsky, Matthias

2013-01-01

We present a new dorsal-ventral stream framework for language comprehension which unifies basic neurobiological assumptions (Rauschecker & Scott, 2009) with a cross-linguistic neurocognitive sentence comprehension model (eADM; Bornkessel & Schlesewsky, 2006). The dissociation between (time-dependent) syntactic structure-building and…

Flour mill stream blending affects sugar snap cookie and Japanese sponge cake quality and oxidative cross-linking potential of soft white wheat.

PubMed

Ramseyer, Daniel D; Bettge, Arthur D; Morris, Craig F

2011-01-01

The purpose of this research was to study the functional differences between straight grade (75% extraction rate) and patent (60% extraction rate) flour blends from 28 genetically pure soft white and club wheat grain lots, as evidenced by variation in sugar snap cookie and Japanese sponge cake quality. Functional differences were examined relative to arabinoxylan content, protein content, and oxidative cross-linking potential of flour slurries. Oxidative cross-linking measurements were obtained on flour slurries with a low shear Bostwick consistometer and considered endogenous oxidative cross-linking potential (water alone) or enhanced oxidative cross-linking potential (with added hydrogen peroxide-peroxidase). A 2-way ANOVA indicated that flour blend was the greater source of variation compared to grain lot for all response variables except water-extractable arabinoxylan content. Patent flours produced larger sugar snap cookies and Japanese sponge cakes, and contained significantly less total and water-unextractable arabinoxylans, protein, and ash than did straight grade flours. Patent flours produced more viscous slurries for endogenous and enhanced cross-linking measurements compared to the straight grade flours. The functional differences between patent and straight grade flours appear to be related to the particular mill streams that were utilized in the formulation of the 2 flour blends and compositional differences among those streams. Journal of Food Science © 2011 Institute of Food Technologists® No claim to original US government works.

Modeling Hydrologic Processes after Vegetation Restoration in an Urban Watershed with HEC-HMS

NASA Astrophysics Data System (ADS)

Stevenson, K.; Kinoshita, A. M.

2017-12-01

The San Diego River Watershed in California (USA) is highly urbanized, where stream channel geomorphology are directly affected by anthropogenic disturbances. Flooding and water quality concerns have led to an increased interest in improving the condition of urban waterways. Alvarado Creek, a 1200-meter section of a tributary to the San Diego River will be used as a case study to understand the degree to which restoration efforts reduce the impacts of climate change and anthropogenic activities on hydrologic processes and water quality in urban stream ecosystems. In 2016, non-native vegetation (i.e. Washingtonia spp. (fan palm), Phoenix canariensis (Canary Island palm)) and approximately 7257 kilograms of refuse were removed from the study reach. This research develops the United States Army Corp of Engineers Hydrologic Engineering Center's Hydraulic Modeling System (USACE HEC-HMS) using field-based data to model and predict the short- and long-term impacts of restoration on geomorphic and hydrologic processes. Observations include cross-sectional area, grain-size distributions, water quality, and continuous measurements of streamflow, temperature, and precipitation. Baseline and design storms are simulated before and after restoration. The model will be calibrated and validated using field observations. The design storms represent statistical likelihoods of storms occurrences, and the pre- and post-restoration hydrologic responses will be compared to evaluate the impact of vegetation and waste removal on runoff processes. Ultimately model parameters will be transferred to other urban creeks in San Diego that may potentially undergo restoration. Modeling will be used to learn about the response trajectory of rainfall-runoff processes following restoration efforts in urban streams and guide future management and restoration activities.

Method of measuring the mass flow rate of a substance entering a cocurrent fluid stream

DOEpatents

Cochran, Jr., Henry D.

1978-04-11

This invention relates to an improved method of monitoring the mass flow rate of a substance entering a cocurrent fluid stream. The method very basically consists of heating equal sections of the fluid stream above and below the point of entry of the substance to be monitored, and measuring and comparing the resulting change in temperature of the sections. Advantage is taken of the difference in thermal characteristics of the fluid and the substance to be measured to correlate temperature differences in the sections above and below the substance feed point for providing an indication of the mass flow rate of the substance.

Data Streams: An Overview and Scientific Applications

NASA Astrophysics Data System (ADS)

Aggarwal, Charu C.

In recent years, advances in hardware technology have facilitated the ability to collect data continuously. Simple transactions of everyday life such as using a credit card, a phone, or browsing the web lead to automated data storage. Similarly, advances in information technology have lead to large flows of data across IP networks. In many cases, these large volumes of data can be mined for interesting and relevant information in a wide variety of applications. When the volume of the underlying data is very large, it leads to a number of computational and mining challenges: With increasing volume of the data, it is no longer possible to process the data efficiently by using multiple passes. Rather, one can process a data item at most once. This leads to constraints on the implementation of the underlying algorithms. Therefore, stream mining algorithms typically need to be designed so that the algorithms work with one pass of the data. In most cases, there is an inherent temporal component to the stream mining process. This is because the data may evolve over time. This behavior of data streams is referred to as temporal locality. Therefore, a straightforward adaptation of one-pass mining algorithms may not be an effective solution to the task. Stream mining algorithms need to be carefully designed with a clear focus on the evolution of the underlying data. Another important characteristic of data streams is that they are often mined in a distributed fashion. Furthermore, the individual processors may have limited processing and memory. Examples of such cases include sensor networks, in which it may be desirable to perform in-network processing of data stream with limited processing and memory [1, 2]. This chapter will provide an overview of the key challenges in stream mining algorithms which arise from the unique setup in which these problems are encountered. This chapter is organized as follows. In the next section, we will discuss the generic challenges that stream mining poses to a variety of data management and data mining problems. The next section also deals with several issues which arise in the context of data stream management. In Sect. 3, we discuss several mining algorithms on the data stream model. Section 4 discusses various scientific applications of data streams. Section 5 discusses the research directions and conclusions.

Water quality effects and placement of pasture best management practices in the Spring Creek Watershed (Centre County, PA)

USDA-ARS?s Scientific Manuscript database

Pasture-based best management practices (BMPs), including stream bank fencing, stream crossings, and bank stabilization, improved water quality ten years after installation by reducing sediment, but did not affect nitrogen concentration. Abundance and diversity of aquatic macroinvertebrates increas...

Exploring lag times between monthly atmospheric deposition and stream chemistry in Appalachian Forest using cross-correlation

USDA-ARS?s Scientific Manuscript database

Although long-term reductions in surface water nitrogen and sulfate concentrations have been widely observed in response to reductions in atmospheric deposition, documenting and inter-relating transient variations in deposition and stream time series has proven problematical due to low signal-to-noi...

The NASA Langley Isolator Dynamics Research Lab

NASA Technical Reports Server (NTRS)

Middleton, Troy F.; Balla, Robert J.; Baurle, Robert A.; Humphreys, William M.; Wilson, Lloyd G.

2010-01-01

The Isolator Dynamics Research Lab (IDRL) is under construction at the NASA Langley Research Center in Hampton, Virginia. A unique test apparatus is being fabricated to support both wall and in-stream measurements for investigating the internal flow of a dual-mode scramjet isolator model. The test section is 24 inches long with a 1-inch by 2-inch cross sectional area and is supplied with unheated, dry air through a Mach 2.5 converging-diverging nozzle. The test section is being fabricated with two sets (glass and metallic) of interchangeable sidewalls to support flow visualization and laser-based measurement techniques as well as static pressure, wall temperature, and high frequency pressure measurements. During 2010, a CFD code validation experiment will be conducted in the lab in support of NASA s Fundamental Aerodynamics Program. This paper describes the mechanical design of the Isolator Dynamics Research Lab test apparatus and presents a summary of the measurement techniques planned for investigating the internal flow field of a scramjet isolator model.

Influence of wood on invertebrate communities in streams and rivers

Treesearch

Arthur Benke; J. Bruce Wallace

2010-01-01

Wood plays a major role in creating multiple invertebrate habitats in small streams and large rivers. In small streams, wood debris dams are instrumental in creating a step and pool profile of habitats, enhancing habitat heterogeneity, retaining organic matter, and changing current velocity. Beavers can convert sections of free-flowing streams into ponds and wetlands...

Level II scour analysis for Bridge 33 (CONCTH00580033) on Town Highway 58, crossing Miles Stream, Concord, Vermont

USGS Publications Warehouse

Burns, Ronda L.

1997-01-01

This report provides the results of a detailed Level II analysis of scour potential at structure CONCTH00580033 on Town Highway 58 crossing Miles Stream, Concord, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the New England Upland section of the New England physiographic province in northeastern Vermont. The 17.9-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is pasture upstream of the bridge while the immediate banks have dense woody vegetation. Downstream of the bridge, the right bank is forested and the left bank has shrubs and brush. In the study area, Miles Stream has an incised, sinuous channel with a slope of approximately 0.01 ft/ft, an average channel top width of 91 ft and an average bank height of 7 ft. The channel bed material ranges from gravel to boulder with a median grain size (D50) of 61.6 mm (0.188 ft). The geomorphic assessment at the time of the Level I and Level II site visit on August 15, 1995, indicated that the reach was stable. The Town Highway 58 crossing of Miles Stream is a 44-ft-long, two-lane bridge consisting of one 39-foot steel-beam span (Vermont Agency of Transportation, written communication, March 24, 1995). The opening length of the structure parallel to the bridge face is 37.4 ft. The bridge is supported by vertical, concrete abutments with stone fill in front creating spillthrough embankments. The channel is skewed approximately 20 degrees to the opening while the opening-skew-to-roadway is zero degrees. The only scour countermeasure at the site was type-3 stone fill (less than 48 inches diameter) along the left and right banks upstream, in front of the abutments forming spill through embankments, and extending along the banks downstream. Additional details describing conditions at the site are included in the Level II Summary and Appendices D and E. Scour depths and recommended rock rip-rap sizes were computed using the general guidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995) for the 100- and 500-year discharges. In addition, the incipient roadway-overtopping discharge is determined and analyzed as another potential worst-case scour scenario. Total scour at a highway crossing is comprised of three components: 1) long-term streambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is the sum of the three components. Equations are available to compute depths for contraction and local scour and a summary of the results of these computations follows. Contraction scour for all modelled flows ranged from 0.0 to 1.8 ft. The worst-case contraction scour occurred at the 500-year discharge. Abutment scour ranged from 4.0 to 9.7 ft. The worst-case abutment scour occurred at the 500-year discharge for the right abutment and at the incipient roadway-overtopping discharge for the left abutment. Additional information on scour depths and depths to armoring are included in the section titled “Scour Results”. Scoured-streambed elevations, based on the calculated scour depths, are presented in tables 1 and 2. A cross-section of the scour computed at the bridge is presented in figure 8. Scour depths were calculated assuming an infinite depth of erosive material and a homogeneous particle-size distribution. It is generally accepted that the Froehlich equation (abutment scour) gives “excessively conservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, computed scour depths are evaluated in combination with other information including (but not limited to) historical performance during flood events, the geomorphic stability assessment, existing scour protection measures, and the results of the hydraulic analyses. Therefore, scour depths adopted by VTAOT may differ from the computed values documented herein.

Blindness alters the microstructure of the ventral but not the dorsal visual stream.

PubMed

Reislev, Nina L; Kupers, Ron; Siebner, Hartwig R; Ptito, Maurice; Dyrby, Tim B

2016-07-01

Visual deprivation from birth leads to reorganisation of the brain through cross-modal plasticity. Although there is a general agreement that the primary afferent visual pathways are altered in congenitally blind individuals, our knowledge about microstructural changes within the higher-order visual streams, and how this is affected by onset of blindness, remains scant. We used diffusion tensor imaging and tractography to investigate microstructural features in the dorsal (superior longitudinal fasciculus) and ventral (inferior longitudinal and inferior fronto-occipital fasciculi) visual pathways in 12 congenitally blind, 15 late blind and 15 normal sighted controls. We also studied six prematurely born individuals with normal vision to control for the effects of prematurity on brain connectivity. Our data revealed a reduction in fractional anisotropy in the ventral but not the dorsal visual stream for both congenitally and late blind individuals. Prematurely born individuals, with normal vision, did not differ from normal sighted controls, born at term. Our data suggest that although the visual streams are structurally developing without normal visual input from the eyes, blindness selectively affects the microstructure of the ventral visual stream regardless of the time of onset. We suggest that the decreased fractional anisotropy of the ventral stream in the two groups of blind subjects is the combined result of both degenerative and cross-modal compensatory processes, affecting normal white matter development.

Hydrologic, ecologic, and geomorphic responses of Brewery Creek to construction of a residential subdivision, Dane County, Wisconsin, 1999-2002

USGS Publications Warehouse

Selbig, William R.; Jopke, Peter L.; Marhshall, David W.; Sorge, Michael J.

2004-01-01

Other physical, biological, and ecological surveys including macroinvertebrates, fish, habitat, and geomorphology were done on segments of Brewery Creek affected by the study area. Macroinvertebrate sampling results (Hilsenhoff Biotic Index value, or HBI), on Brewery Creek ranged from 'very good' to 'good' water-quality with no appreciable differences during any phase of construction activity. Results for fish-community composition, however, were within the 'poor' range (Index of Biotic Integrity value, or IBI) during each year of testing. A general absence of intolerant species, with the exception of brown trout, reflects the low IBI values. Habitat values did not change significantly from preconstruction to postconstruction phases. Although installation of a double-celled culvert in Brewery Creek most likely altered the width-to-depth ratio in that reach, the overall habitat rating remained 'fair'. Fluvial geomorphology classifications including channel cross sections, bed- and bank-erosion surveys, and pebble counts did not indicate that stream geomorphic characteristics were altered by home-construction activity in the study area. Increases in fine-grained sediment at various cross sections were attributed to instream erosion processes, such as bank slumping, rather than increases in sediment delivery from the nearby construction site.

Aerodynamic design of gas and aerosol samplers for aircraft

NASA Technical Reports Server (NTRS)

Soderman, Paul T.; Hazen, Nathan L.; Brune, William H.

1991-01-01

The aerodynamic design of airborne probes for the capture of air and aerosols is discussed. Emphasis is placed on the key parameters that affect proper sampling, such as inlet-lip design, internal duct components for low pressure drop, and exhaust geometry. Inlet designs that avoid sonic flow conditions on the lip and flow separation in the duct are shown. Cross-stream velocities of aerosols are expressed in terms of droplet density and diameter. Flow curvature, which can cause aerosols to cross streamlines and impact on probe walls, can be minimized by means of a proper inlet shape and proper probe orientation, and by avoiding bends upstream of the test section. A NASA panel code called PMARC was used successfully to compute streamlines around aircraft and probes, as well as to compute to local velocity and pressure distributions in inlets. A NACA 1-series inlet with modified lip radius was used for the airborne capture of stratospheric chlorine monoxide at high altitude and high flight speed. The device has a two-stage inlet that decelerates the inflow with little disturbance to the flow through the test section. Diffuser design, exhaust hood design, valve loss, and corner vane geometry are discussed.

COMPARTMENTAL MODEL OF NITRATE RETENTION IN STREAMS

EPA Science Inventory

A compartmental modeling approach is presented to route nitrate retention along a cascade of stream reach sections. A process transfer function is used for transient storage equations with first order reaction terms to represent nitrate uptake in the free stream, and denitrifica...

40 CFR 230.45 - Riffle and pool complexes.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 25 2011-07-01 2011-07-01 false Riffle and pool complexes. 230.45... Impacts on Special Aquatic Sites § 230.45 Riffle and pool complexes. (a) Steep gradient sections of streams are sometimes characterized by riffle and pool complexes. Such stream sections are recognizable by...

40 CFR 230.45 - Riffle and pool complexes.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Riffle and pool complexes. 230.45... Impacts on Special Aquatic Sites § 230.45 Riffle and pool complexes. (a) Steep gradient sections of streams are sometimes characterized by riffle and pool complexes. Such stream sections are recognizable by...

Unsteady Heat Transfer in Channel Flow using Small-Scale Vorticity Concentrations Effected by a Vibrating Reed

NASA Astrophysics Data System (ADS)

Hidalgo, Pablo; Glezer, Ari

2011-11-01

Heat transfer enhancement by small-scale vorticity concentrations that are induced within the core flow of a mm-scale heated channel are investigated experimentally. These small-scale motions are engendered by the cross stream vibrations of a streamwise cantilevered reed that spans most of the channel's width. The interactions between the reed the core flow over a range of flow rates lead to the formation, shedding, and advection of time-periodic vorticity concentrations that interact with the wall boundary layers, and increase cross stream mixing of the core flow. Heating of the channel walls is controlled using microfabricated serpentine resistive heaters embedded with streamwise arrays of temperature sensors. It is shown that the actuation disrupts the thermal boundary layers and result in significant enhancement of the local and global heat transfer along the channel compared to the baseline flow in the absence of the reed. The effect of the reed on the cross flow is measured using high resolution particle image velocimetry (PIV), and the reed motion is characterized using a laser-based position sensor. The blockage induced by the presence of the reed and its cross stream motion is characterized using detailed streamwise pressure distributions. Supported by DARPA and UTRC.

Regional bankfull geometry relationships for southern California mountain streams and hydrologic applications

NASA Astrophysics Data System (ADS)

Modrick, Theresa M.; Georgakakos, Konstantine P.

2014-09-01

This study develops and intercompares regional relationships for bankfull channel width, hydraulic depth, and cross-sectional area for southern California mountain streams based on several data sources: surveyed streams, US Geological Survey stream survey reports, and existing literature. Although considerable uncertainty exists in estimating bankfull conditions, the relationships developed from the varying data sources show significant agreement. For small watersheds with drainage area ranging from 15 to ~ 2000 km2, the estimates of bankfull top width ranged from 7.2 to 44.5 m and hydraulic depth estimates ranged from 0.35 to 1.15 m. The utility of the developed bankfull geometry regional curves is demonstrated for southern California catchments through (a) the computation of the bankfull discharge and (b) the estimation of the surface runoff response necessary to produce bankfull conditions in the streams at the outlet of these catchments. For selected locations with instantaneous flow records, the occurrence frequency of events exceeding bankfull flow was examined for the available 10-15 year span of observational records. Bankfull discharge estimates for all small watersheds in the region ranged from 1.3 to 74 m3/s, while the range at the selected gauged stream locations was from 2.6 to 16.4 m3/s. Stream locations along the Transverse Mountains of southern California showed an average occurrence frequency of less than 1 year, whereas along the Peninsular Mountains the average return period tended to be greater than 1 year. The application of the regional curves to the estimation of the surface runoff response necessary to produce bankfull conditions at the channel outlets of small catchments may be used as an index for conditions of minor flooding with saturated soils. This surface runoff response index ranges from 2.0 to 5.5 mm for a 3-hour rainfall duration for southern California watersheds greater than 15 km2 in area. Differences between the values for the Peninsular and Transverse Mountain Ranges are linked to geological, climatic, and geomorphologic differences. The developed regional geometry relationships are suitable for use in various hydrologic modeling applications, including distributed modeling with high resolution pertinent to flash flood forecasting.

Morphological Analyses and Simulated Flood Elevations in a Watershed with Dredged and Leveed Stream Channels, Wheeling Creek, Eastern Ohio

USGS Publications Warehouse

Sherwood, James M.; Huitger, Carrie A.; Ebner, Andrew D.; Koltun, G.F.

2008-01-01

The USGS, in cooperation with the Ohio Emergency Management Agency, conducted a study in the Wheeling Creek Basin to (1) evaluate and contrast land-cover characteristics from 2001 with characteristics from 1979 and 1992; (2) compare current streambed elevation, slope, and geometry with conditions present in the late 1980s; (3) look for evidence of channel filling and over widening in selected undredged reaches; (4) estimate flood elevations for existing conditions in both undredged and previously dredged reaches; (5) evaluate the height of the levees required to contain floods with selected recurrence intervals in previously dredged reaches; and (6) estimate flood elevations for several hypothetical dredging and streambed aggradation scenarios in undredged reaches. The amount of barren land in the Wheeling Creek watershed has decreased from 20 to 1 percent of the basin area based on land-cover characteristics from 1979 and 2001. Barren lands appear to have been converted primarily to pasture, presumably as a result of surface-mine reclamation. Croplands also decreased from 13 to 8 percent of the basin area. The combined decrease in barren lands and croplands is approximately offset by the increase in pasture. Stream-channel surveys conducted in 1987 and again in 2006 at 21 sites in four previously dredged reaches of Wheeling Creek indicate little change in the elevation, slope, and geometry of the channel at most sites. The mean change in width-averaged bed and thalweg elevations for the 21 cross sections was 0.1 feet. Bankfull widths, mean depths, and cross-sectional areas measured at 12 sites in undredged reaches were compared to estimates determined from regional equations. The mean percentage difference between measured and estimated bankfull widths was -0.2 percent, suggesting that bankfull widths in the Wheeling Creek Basin are generally about the same as regional averages for undisturbed basins of identical drainage area. For bankfull mean depth and cross-sectional area, the mean percentage differences between the measured and estimated values were -16.0 and -11.2, respectively. The predominantly negative bias in differences between the measured and estimated values indicates that bankfull mean depths and cross-sectional areas in studied reaches generally are smaller than the regional trend. This may be an indication of channel filling and over widening or it may reflect insufficient representation in the regional dataset of basins with characteristics like that of Wheeling Creek. Step-backwater models were constructed for four previously dredged reaches to determine the height of levees required to contain floods with recurrence intervals of 2, 10, 50, and 100 years. Existing levees (all of which are uncertified) were found to contain the 100-year flood at only 20 percent of the surveyed cross sections. At the other 80 percent of the surveyed cross sections, levee heights would have to be raised an average of 2.5 feet and as much as 6.3 feet to contain the 100-year flood. Step-backwater models also were constructed for three undredged reaches to assess the impacts of selected dredging and streambed aggradation scenarios on water-surface elevations corresponding to the 2-, 10-, 50-, and 100-year floods. Those models demonstrated that changes in water-surface elevations associated with a given depth of dredging were proportionately smaller for larger floods due to the fact that more of the flood waters are outside of the main channel. For example, 2.0 feet of dredging in the three study reaches would lower the water-surface elevation an average of 1.30 feet for the 2-year flood and 0.64 feet for the 100-year flood.

Quantifying spatial scaling patterns and their local and regional correlates in headwater streams: Implications for resilience

USGS Publications Warehouse

Gothe, Emma; Sandin, Leonard; Allen, Craig R.; Angeler, David G.

2014-01-01

The distribution of functional traits within and across spatiotemporal scales has been used to quantify and infer the relative resilience across ecosystems. We use explicit spatial modeling to evaluate within- and cross-scale redundancy in headwater streams, an ecosystem type with a hierarchical and dendritic network structure. We assessed the cross-scale distribution of functional feeding groups of benthic invertebrates in Swedish headwater streams during two seasons. We evaluated functional metrics, i.e., Shannon diversity, richness, and evenness, and the degree of redundancy within and across modeled spatial scales for individual feeding groups. We also estimated the correlates of environmental versus spatial factors of both functional composition and the taxonomic composition of functional groups for each spatial scale identified. Measures of functional diversity and within-scale redundancy of functions were similar during both seasons, but both within- and cross-scale redundancy were low. This apparent low redundancy was partly attributable to a few dominant taxa explaining the spatial models. However, rare taxa with stochastic spatial distributions might provide additional information and should therefore be considered explicitly for complementing future resilience assessments. Otherwise, resilience may be underestimated. Finally, both environmental and spatial factors correlated with the scale-specific functional and taxonomic composition. This finding suggests that resilience in stream networks emerges as a function of not only local conditions but also regional factors such as habitat connectivity and invertebrate dispersal.

Falling microbead counter-flow process for separating gas mixtures

DOEpatents

Hornbostel, Marc D.; Krishnan, Gopala N.; Sanjurjo, Angel

2015-07-07

A method and reactor for removing a component from a gas stream is provided. In one embodiment, the method includes providing the gas stream containing the component that is to be removed and adsorbing the component out of the gas stream as the gas stream rises via microbeads of a sorbent falling down an adsorber section of a reactor.

Synthesis and self-assembly of amphiphilic polymeric microparticles.

PubMed

Dendukuri, Dhananjay; Hatton, T Alan; Doyle, Patrick S

2007-04-10

We report the synthesis and self-assembly of amphiphilic, nonspherical, polymeric microparticles. Wedge-shaped particles bearing segregated hydrophilic and hydrophobic sections were synthesized in a microfludic channel by polymerizing across laminar coflowing streams of hydrophilic and hydrophobic polymers using continuous flow lithography (CFL). Particle monodispersity was characterized by measuring both the size of the particles formed and the extent of amphiphilicity. The coefficient of variation (COV) was found to be less than 2.5% in all measured dimensions. Particle structure was further characterized by measuring the curvature of the interface between the sections and the extent of cross-linking using FTIR spectroscopy. The amphiphilic particles were allowed to self-assemble in water or at water-oil interfaces. In water, the geometry of the particles enabled the formation of micelle-like structures, while in emulsions, the particles migrated to the oil-water interface and oriented themselves to minimize their surface energy.

Hydraulic conditions of flood flows in a Polish Carpathian river subjected to variable human impacts

NASA Astrophysics Data System (ADS)

Radecki-Pawlik, Artur; Czech, Wiktoria; Wyżga, Bartłomiej; Mikuś, Paweł; Zawiejska, Joanna; Ruiz-Villanueva, Virginia

2016-04-01

Channel morphology of the Czarny Dunajec River, Polish Carpathians, has been considerably modified as a result of channelization and gravel-mining induced channel incision, and now it varies from a single-thread, incised or regulated channel to an unmanaged, multi-thread channel. We investigated effects of these distinct channel morphologies on the conditions for flood flows in a study of 25 cross-sections from the middle river course where the Czarny Dunajec receives no significant tributaries and flood discharges increase little in the downstream direction. Cross-sectional morphology, channel slope and roughness of particular cross-section parts were used as input data for the hydraulic modelling performed with the 1D steady-flow HEC-RAS model for discharges with recurrence interval from 1.5 to 50 years. The model for each cross-section was calibrated with the water level of a 20-year flood from May 2014, determined shortly after the flood on the basis of high-water marks. Results indicated that incised and channelized river reaches are typified by similar flow widths and cross-sectional flow areas, which are substantially smaller than those in the multi-thread reach. However, because of steeper channel slope in the incised reach than in the channelized reach, the three river reaches differ in unit stream power and bed shear stress, which attain the highest values in the incised reach, intermediate values in the channelized reach, and the lowest ones in the multi-thread reach. These patterns of flow power and hydraulic forces are reflected in significant differences in river competence between the three river reaches. Since the introduction of the channelization scheme 30 years ago, sedimentation has reduced its initial flow conveyance by more than half and elevated water stages at given flood discharges by about 0.5-0.7 m. This partly reflects a progressive growth of natural levees along artificially stabilized channel banks. By contrast, sediments of natural levees deposited along the multi-thread channel and subsequently eroded in the course of lateral channel migration and floodplain reworking; as a result, they do not reduce the conveyance of floodplain flows in this reach. This study was performed within the scope of the Research Project DEC-2013/09/B/ST10/00056 financed by the National Science Centre of Poland.

Options for temporary wetland and stream crossings

Treesearch

Charles R. Blinn; Ricky Dahlman; Lola Hislop; Michael A. Thompson

1999-01-01

Forest management activities and environmental concerns have accelerated significantly in the past 10 years. Worldwide expansion of economies and population has increased the demand for forest products and other uses of forests. These demands have the potential to negatively affect wetlands and streams. Wetlands, as referred to here, are areas containing soil with...

40 CFR 60.741 - Definitions, symbols, and cross-reference tables.

Code of Federal Regulations, 2014 CFR

2014-07-01

.... Cgv = the concentration of VOC in the gas stream entering each individual carbon adsorber vessel (v... vessel, Cgv may be measured in the carbon adsorption system's common inlet duct prior to the branching of individual inlet ducts. Chv = the concentration of VOC in the gas stream exiting each individual carbon...

40 CFR 60.741 - Definitions, symbols, and cross-reference tables.

Code of Federal Regulations, 2011 CFR

2011-07-01

.... Cgv=the concentration of VOC in the gas stream entering each individual carbon adsorber vessel (v), in... vessel, Cgv may be measured in the carbon adsorption system's common inlet duct prior to the branching of individual inlet ducts. Chv=the concentration of VOC in the gas stream exiting each individual carbon...

40 CFR 60.741 - Definitions, symbols, and cross-reference tables.

Code of Federal Regulations, 2012 CFR

2012-07-01

.... Cgv=the concentration of VOC in the gas stream entering each individual carbon adsorber vessel (v), in... vessel, Cgv may be measured in the carbon adsorption system's common inlet duct prior to the branching of individual inlet ducts. Chv=the concentration of VOC in the gas stream exiting each individual carbon...

40 CFR 60.741 - Definitions, symbols, and cross-reference tables.

Code of Federal Regulations, 2013 CFR

2013-07-01

.... Cgv=the concentration of VOC in the gas stream entering each individual carbon adsorber vessel (v), in... vessel, Cgv may be measured in the carbon adsorption system's common inlet duct prior to the branching of individual inlet ducts. Chv=the concentration of VOC in the gas stream exiting each individual carbon...

Sediment concentration and turbidity changes during culvert removals

Treesearch

Randy B. Foltz; Kristina A. Yanosek; Timothy M. Brown

2008-01-01

The concentrations of sediment and turbidity in stream water were monitored during culvert removals to determine the short term effects of road obliteration. Sediment concentration was measured at 11 stream crossings among two locations in Idaho and one in Washington. Sediment concentration immediately below the culvert outlet exceeded levels above the culvert outlet...

Improving stream studies with a small-footprint green lidar

USGS Publications Warehouse

McKean, Jim; Isaak, Dan; Wright, Wayne

2009-01-01

Technology is changing how scientists and natural resource managers describe and study streams and rivers. A new generation of airborne aquatic-terrestrial lidars is being developed that can penetrate water and map the submerged topography inside a stream as well as the adjacent subaerial terrain and vegetation in one integrated mission. A leading example of these new cross-environment instruments is the Experimental Advanced Airborne Research Lidar (EAARL), a NASAbuilt sensor now operated by the U.S. Geological Survey (USGS) [Wright and Brock, 2002].

Evaluation of Impinging Stream Vortex Chamber Concepts for Liquid Rocket Engine Applications

NASA Technical Reports Server (NTRS)

Trinh, Huu; Kopicz, Charles; Bullard, Brad; Michaels, Scott

2003-01-01

NASA Marshall Space Flight Center (MSFC) and the U. S. Army are jointly investigating vortex chamber concepts for cryogenic oxygen/hydrocarbon fuel rocket engine applications. One concept, the Impinging Stream Vortex Chamber Concept (ISVC), has been tested with gel propellants at AMCOM at Redstone Arsenal, Alabama. A version of this concept for the liquid oxygen (LOX)/hydrocarbon fuel (RP-1) propellant system is derived from the one for the gel propellant. An unlike impinging injector is employed to deliver the propellants to the chamber. MSFC has also designed two alternative injection schemes, called the chasing injectors, associated with this vortex chamber concept. In these injection techniques, both propellant jets and their impingement point are in the same chamber cross-sectional plane. One injector has a similar orifice size with the original unlike impinging injector. The second chasing injector has small injection orifices. The team has achieved their objectives of demonstrating the self-cooled chamber wall benefits of ISVC and of providing the test data for validating computational fluids dynamics (CFD) models. These models, in turn, will be used to design the optimum vortex chambers in the future.

Demonstration of Imaging Flow Diagnostics Using Rayleigh Scattering in Langley 0.3-Meter Transonic Cryogenic Tunnel

NASA Technical Reports Server (NTRS)

Shirinzadeh, B.; Herring, G. C.; Barros, Toya

1999-01-01

The feasibility of using the Rayleigh scattering technique for molecular density imaging of the free-stream flow field in the Langley 0.3-Meter Transonic Cryogenic Tunnel has been experimentally demonstrated. The Rayleigh scattering was viewed with a near-backward geometry with a frequency-doubled output from a diode-pumped CW Nd:YAG laser and an intensified charge-coupled device camera. Measurements performed in the range of free-stream densities from 3 x 10(exp 25) to 24 x 10(exp 25) molecules/cu m indicate that the observed relative Rayleigh signal levels are approximately linear with flow field density. The absolute signal levels agree (within approx. 30 percent) with the expected signal levels computed based on the well-known quantities of flow field density, Rayleigh scattering cross section for N2, solid angle of collection, transmission of the optics, and the independently calibrated camera sensitivity. These results show that the flow field in this facility is primarily molecular (i.e., not contaminated by clusters) and that Rayleigh scattering is a viable technique for quantitative nonintrusive diagnostics in this facility.

Investigation of a supersonic cruise fighter model flow field

NASA Technical Reports Server (NTRS)

Reubush, D. E.; Bare, E. A.

1985-01-01

An investigation was conducted in the Langley 16-Foot Transonic Tunnel to survey the flow field around a model of a supersonic cruise fighter configuration. Local values of angle of attack, side flow, Mach number, and total pressure ratio were measured with a single multi-holed probe in three survey areas on a model previously used for nacelle/nozzle integration investigations. The investigation was conducted at Mach numbers of 0.6, 0.9, and 1.2, and at angles of attack from 0 deg to 10 deg. The purpose of the investigation was to provide a base of experimental data with which theoretically determined data can be compared. To that end the data are presented in tables as well as graphically, and a complete description of the model geometry is included as fuselage cross sections and wing span stations. Measured local angles of attack were generally greater than free stream angle of attack above the wing and generally smaller below. There were large spanwise local angle-of-attack and side flow gradients above the wing at the higher free stream angles of attack.

Coaxial microreactor for particle synthesis

DOEpatents

Bartsch, Michael; Kanouff, Michael P; Ferko, Scott M; Crocker, Robert W; Wally, Karl

2013-10-22

A coaxial fluid flow microreactor system disposed on a microfluidic chip utilizing laminar flow for synthesizing particles from solution. Flow geometries produced by the mixing system make use of hydrodynamic focusing to confine a core flow to a small axially-symmetric, centrally positioned and spatially well-defined portion of a flow channel cross-section to provide highly uniform diffusional mixing between a reactant core and sheath flow streams. The microreactor is fabricated in such a way that a substantially planar two-dimensional arrangement of microfluidic channels will produce a three-dimensional core/sheath flow geometry. The microreactor system can comprise one or more coaxial mixing stages that can be arranged singly, in series, in parallel or nested concentrically in parallel.

Target detection portal

DOEpatents

Linker, Kevin L.; Brusseau, Charles A.

2002-01-01

A portal apparatus for screening persons or objects for the presence of trace amounts of target substances such as explosives, narcotics, radioactive materials, and certain chemical materials. The portal apparatus can have a one-sided exhaust for an exhaust stream, an interior wall configuration with a concave-shape across a horizontal cross-section for each of two facing sides to result in improved airflow and reduced washout relative to a configuration with substantially flat parallel sides; air curtains to reduce washout; ionizing sprays to collect particles bound by static forces, as well as gas jet nozzles to dislodge particles bound by adhesion to the screened person or object. The portal apparatus can be included in a detection system with a preconcentrator and a detector.

Quantifying peak discharges for historical floods

USGS Publications Warehouse

Cook, J.L.

1987-01-01

It is usually advantageous to use information regarding historical floods, if available, to define the flood-frequency relation for a stream. Peak stages can sometimes be determined for outstanding floods that occurred many years ago before systematic gaging of streams began. In the United States, this information is usually not available for more than 100-200 years, but in countries with long cultural histories, such as China, historical flood data are available at some sites as far back as 2,000 years or more. It is important in flood studies to be able to assign a maximum discharge rate and an associated error range to the historical flood. This paper describes the significant characteristics and uncertainties of four commonly used methods for estimating the peak discharge of a flood. These methods are: (1) rating curve (stage-discharge relation) extension; (2) slope conveyance; (3) slope area; and (4) step backwater. Logarithmic extensions of rating curves are based on theoretical plotting techniques that results in straight line extensions provided that channel shape and roughness do not change significantly. The slope-conveyance and slope-area methods are based on the Manning equation, which requires specific data on channel size, shape and roughness, as well as the water-surface slope for one or more cross-sections in a relatively straight reach of channel. The slope-conveyance method is used primarily for shaping and extending rating curves, whereas the slope-area method is used for specific floods. The step-backwater method, also based on the Manning equation, requires more cross-section data than the slope-area ethod, but has a water-surface profile convergence characteristic that negates the need for known or estimated water-surface slope. Uncertainties in calculating peak discharge for historical floods may be quite large. Various investigations have shown that errors in calculating peak discharges by the slope-area method under ideal conditions for recent floods (i.e., when flood elevations, slope and channel characteristics are reasonably certain), may be on the order of 10-25%. Under less than ideal conditions, where streams are hydraulically steep and rough, errors may be much larger. The additional uncertainties for historical floods created by the passage of time may result in even larger errors of peak discharge. ?? 1987.

New views of the Gulf Stream

NASA Astrophysics Data System (ADS)

Todd, R. E.

2016-02-01

The Gulf Stream plays a major role in the climate system and is a significant forcing agent for the coastal circulation along the US East Coast, yet routine subsurface measurements of Gulf Stream structure are only collected in the Florida Straits and between New Jersey and Bermuda. A recent pilot program demonstrated the feasibility of using underwater gliders to repeatedly survey across the Gulf Stream and to provide subsurface Gulf Stream observations to the community in realtime. Spray gliders were deployed on three-month missions from Miami, Florida to the New England shelf south of Cape Cod, during which they zigzagged back and forth across the Gulf Stream. Three such deployments have been completed so far with a total of more than 20 cross-Gulf Stream transects occupied. These new observations detail the subsurface structure and variability of the Gulf Stream upstream and downstream of its separation from the continental margin, reveal large-amplitude internal waves within the boundary current, and capture numerous eddies along the flanks of the Gulf Stream. Future routine glider deployments in the Gulf Stream promise to provide critical observations for examining inherent Gulf Stream variability, investigating western boundary current influences on coastal circulation, and constraining numerical simulations.

The Influence of Boundary Layer Parameters on Interior Noise

NASA Technical Reports Server (NTRS)

Palumbo, Daniel L.; Rocha, Joana

2012-01-01

Predictions of the wall pressure in the turbulent boundary of an aerospace vehicle can differ substantially from measurement due to phenomena that are not well understood. Characterizing the phenomena will require additional testing at considerable cost. Before expending scarce resources, it is desired to quantify the effect of the uncertainty in wall pressure predictions and measurements on structural response and acoustic radiation. A sensitivity analysis is performed on four parameters of the Corcos cross spectrum model: power spectrum, streamwise and cross stream coherence lengths and Mach number. It is found that at lower frequencies where high power levels and long coherence lengths exist, the radiated sound power prediction has up to 7 dB of uncertainty in power spectrum levels with streamwise and cross stream coherence lengths contributing equally to the total.

Learning Across Senses: Cross-Modal Effects in Multisensory Statistical Learning

PubMed Central

Mitchel, Aaron D.; Weiss, Daniel J.

2014-01-01

It is currently unknown whether statistical learning is supported by modality-general or modality-specific mechanisms. One issue within this debate concerns the independence of learning in one modality from learning in other modalities. In the present study, the authors examined the extent to which statistical learning across modalities is independent by simultaneously presenting learners with auditory and visual streams. After establishing baseline rates of learning for each stream independently, they systematically varied the amount of audiovisual correspondence across 3 experiments. They found that learners were able to segment both streams successfully only when the boundaries of the audio and visual triplets were in alignment. This pattern of results suggests that learners are able to extract multiple statistical regularities across modalities provided that there is some degree of cross-modal coherence. They discuss the implications of their results in light of recent claims that multisensory statistical learning is guided by modality-independent mechanisms. PMID:21574745

Litter breakdown and invertebrate detritivores in a resource-depleted Appalachian stream

Treesearch

Susan L. Eggert; J. Bruce Wallace

2003-01-01

We measured breakdown rates of leaves and small wood for the first three years in a stream in which detrital inputs were excluded for 7 years and in a reference stream located in the Appalachian Mountains of North Carolina, USA. Leaf and wood inputs were excluded using a gill-net canopy constructed over a 170-m section of stream. We hypothesized that red maple (

Erosion and sediment delivery following removal of forest roads

USGS Publications Warehouse

Madej, Mary Ann

2001-01-01

Erosion control treatments were applied to abandoned logging roads in California, with the goal of reducing road-related sediment input to streams and restoring natural hydrologic patterns on the landscape. Treatment of stream crossings involved excavating culverts and associated road fill and reshaping streambanks. A variety of techniques were applied to road benches, which included decompacting the road surface, placing unstable road fill in more stable locations, and re-establishing natural surface drainage patterns. Following treatment and a 12-year recurrence-interval storm, some road reaches and excavated stream crossings showed evidence of mass movement failures, gullying, bank erosion and channel incision. Post-treatment erosion from excavated stream crossings was related to two variables: a surrogate for stream power (drainage area × channel gradient) and the volume of fill excavated from the channel. Post-treatment erosion on road reaches was related to four explanatory variables: method of treatment, hillslope position (upper, mid-slope or lower), date of treatment, and an interaction term (hillslope position × method of treatment). Sediment delivery from treated roads in upper, middle and lower hillslope positions was 10, 135 and 550 m3 of sediment per kilometre of treated roads, respectively. In contrast, inventories of almost 500 km of forest roads in adjacent catchments indicate that untreated roads produced 1500 to 4700 m3 of sediment per kilometre of road length. Erosion from 300 km of treated roads contributed less than 2 per cent of the total sediment load of Redwood Creek during the period 1978 to 1998. Although road removal treatments do not completely eliminate erosion associated with forest roads, they do substantially reduce sediment yields from abandoned logging roads.

Monitoring and modeling of runoff from a natural and an urbanized part of a small stream catchment

NASA Astrophysics Data System (ADS)

Kalicz, P.; Kucsara, M.; Gribovszki, Z.; Erős, M.; Csáfordi, P.

2012-04-01

Runoff processes in natural catchments are significantly different compared to urbanized areas. Human impacts are manifested in high amount of paved surfaces like roofs, roads, parking plots and the compacted soils of quasi natural areas like public gardens and parks. Decay of permeability and storage capacity both induce higher amount of runoff. The common practice to treat the increased volume of runoff is to collect in pipes and drain to a stream as soon as possible. These interventions induce flash floods with smaller time of concentration and higher flood peaks as normal food waves therefore strongly load discharge capacity of stream channel. Streams in urban areas are strongly modified and regulated. Sometimes the stream channel are dredged out to increase the discharge capacity. In worst case some smaller brooks are crowded with lid to increase urbanized habitat. Many climate change scenarios predict higher probability of heavy storm events, therefore increasing volume of runoff induces higher demands of strongly modified and enormous concrete channels. This study presents one year monitoring of a small stream comparing runoff from natural, rural and urban sections. In this paper we also introduce the process of a model setup and an evaluation to investigate the weak points of a stream section in urbanized areas. The pilot area of this research is the Rák Brook which is the second largest stream of city Sopron (western Hungary). The natural headwater catchment is long-term research area of Hidegvíz Valley Project, therefore we had a good basis to extend the research catchment monitoring in the direction of urbanized lower part of the stream. Seven monitoring points are established along the longitudinal section of the stream. In each point the water stage is recorded continuously beside several other water quality parameters. These data sets help the later validation of the hydrodynamic model.

Continuous cell introduction and rapid dynamic lysis for high-throughput single-cell analysis on microfludic chips with hydrodynamic focusing.

PubMed

Xu, Chun-Xiu; Yin, Xue-Feng

2011-02-04

A chip-based microfluidic system for high-throughput single-cell analysis is described. The system was integrated with continuous introduction of individual cells, rapid dynamic lysis, capillary electrophoretic (CE) separation and laser induced fluorescence (LIF) detection. A cross microfluidic chip with one sheath-flow channel located on each side of the sampling channel was designed. The labeled cells were hydrodynamically focused by sheath-flow streams and sequentially introduced into the cross section of the microchip under hydrostatic pressure generated by adjusting liquid levels in the reservoirs. Combined with the electric field applied on the separation channel, the aligned cells were driven into the separation channel and rapidly lysed within 33ms at the entry of the separation channel by Triton X-100 added in the sheath-flow solution. The maximum rate for introducing individual cells into the separation channel was about 150cells/min. The introduction of sheath-flow streams also significantly reduced the concentration of phosphate-buffered saline (PBS) injected into the separation channel along with single cells, thus reducing Joule heating during electrophoretic separation. The performance of this microfluidic system was evaluated by analysis of reduced glutathione (GSH) and reactive oxygen species (ROS) in single erythrocytes. A throughput of 38cells/min was obtained. The proposed method is simple and robust for high-throughput single-cell analysis, allowing for analysis of cell population with considerable size to generate results with statistical significance. Copyright © 2010 Elsevier B.V. All rights reserved.

Response and Recovery of Streams From an Extreme Flood

NASA Astrophysics Data System (ADS)

Kantack, K. M.; Renshaw, C. E.; Magilligan, F. J.; Dethier, E.

2015-12-01

In temperate regions, channels are expected to recover from intense floods in a matter of months to years, but quantitative empirical support for this idea remains limited. Moreover, existing literature fails to address the spatial variability of the recovery process. Using an emerging technology, we investigate the immediate response to and progressive recovery of channels in the Northeastern United States from an extreme flood. We seek to determine what factors, including the nature and extent of the immediate response of the channel to the flood and post-flood availability of sediment, contribute to the spatial variability of the rate of recovery. Taking advantage of the 2011 flooding from Tropical Storm Irene, for which pre- and post-flood aerial lidar exist, along with a third set of terrestrial lidar collected in 2015, we assess channel response and recovery with multi-temporal lidar comparison. This method, with kilometers of continuous data, allows for analysis beyond traditional cross-section and reach-scale studies. Results indicate that landscape-scale factors, such as valley morphology and gradients in unit stream power, are controls on channel response to the flood, producing spatially variable impacts. Along a 16.4-km section (drainage area = 82 km2) of the Deerfield River in Vermont, over 148,000 m3 or erosion occurred during the flood. The spatial variation of impacts was correlated (R2= 0.476) with the ratio of channel width to valley width. We expect the recovery process will similarly exhibit spatial variation in rate and magnitude, possibly being governed by gradients in unit stream power and sediment availability. We test the idea that channel widening during the flood reduces post-flood unit stream power, creating a pathway for deposition and recovery to pre-flood width. Flood-widened reaches downstream of point-sources of sediment, such as landslides, will recover more quickly than those without consistent sediment supply. Results of this study will improve our ability to predict the nature and location of flood impacts and determine what factors contribute to the spatial variability of channel recovery.

Bed-material entrainment and associated transportation infrastructure problems in streams of the Edwards Plateau, central Texas

USGS Publications Warehouse

Heitmuller, Franklin T.; Asquith, William H.

2008-01-01

The Texas Department of Transportation commonly builds and maintains low-water crossings (LWCs) over streams in the Edwards Plateau in Central Texas. LWCs are low-height structures, typically constructed of concrete and asphalt, that provide acceptable passage over seasonal rivers or streams with relatively low normal-depth flow. They are designed to accommodate flow by roadway overtopping during high-flow events. The streams of the Edwards Plateau are characterized by cobble- and gravel-sized bed material and highly variable flow regimes. Low base flows that occur most of the time occasionally are interrupted by severe floods. The floods entrain and transport substantial loads of bed material in the stream channels. As a result, LWCs over streams in the Edwards Plateau are bombarded and abraded by bed material during floods and periodically must be maintained or even replaced.

Temporal Differences in Flow Depth and Velocity Distributions and Hydraulic Microhabitats Near Bridges of the Lower Platte River, Nebraska, 1934-2006

USGS Publications Warehouse

Ginting, Daniel; Zelt, Ronald B.

2008-01-01

As part of a collaborative study of the cumulative impacts on stream and riparian ecology of water and channel management practices in the lower Platte River, Nebraska, this report describes a study by the U.S. Geological Survey in cooperation with the Lower Platte South Natural Resources District that summarizes: (1) temporal differences in distribution of streamflow depth, velocity, and microhabitats among five discrete 11-water-year periods 1934-44, 1951-61, 1966-76, 1985-95, and 1996-2006, and (2) the effects of bridge proximity on distribution of streamflow depth, velocity, and microhabitat of the Platte River when cross sections were measured at a similar discharge. The scope of the study included the four presently (2008) active streamflow-gaging stations located near bridges over the lower Platte River at North Bend, near Leshara, near Ashland, and at Louisville, Nebraska, and the most downstream streamflow-gaging station within the central Platte River segment near Duncan, Nebraska. Generally, in cases where temporal differences in streamflow depth and velocity were evident, at least one of the water-year periods from 1934 through 1995 had deeper streamflow than the recent water-year period (1996-2006). Temporal differences in distributions of streamflow depth were not strongly associated with differences in either climatic conditions or the maximum peak flow that occurred prior to the latest discharge measurement during each period. The relative cross-sectional area of most hydraulic niches did not differ among the water-year periods. Part of this apparent uniformity likely was an artifact of the broad microhabitat classification used for this study. In cases where temporal differences in relative cross-sectional area of hydraulic niches were evidenced, the differences occurred during high- and low-flow conditions, not during median flow conditions. The temporal differences in relative cross-sectional area were found more frequently for hydraulic niches defined by moderate and fast velocities than for hydraulic niches defined by slow velocities. Generally, any significant increase or decrease in the relative cross-sectional areas of hydraulic niches during the water-year periods from 1934 through 1995 had disappeared during the most recent water-year period, 1996-2006. Deep-Swift niche was the predominant hydraulic niche for all near-bridge sites on the lower Platte River for high- and median-flow conditions. The Deep-Swift niche also was the predominant niche for the near-bridge sites near Ashland and at Louisville for low-flow conditions; for the near-bridge sites at North Bend and near Leshara, streamflow cross-sectional areas during low-flow conditions were shared among the Shallow-Moderate, Intermediate-Moderate, Intermediate-Swift, and Deep-Swift hydraulic niches. For the near-bridge site near Duncan, the site farthest downstream in the central Platte River system, the Deep-Swift hydraulic niche was predominant only during high-flow conditions; during median- and low-flow conditions the relative cross-sectional area was shared among the Shallow-Slow, Shallow-Moderate, Intermediate-Moderate, and Intermediate-Swift hydraulic niches. Significant temporal differences in the relative cross-sectional area of the Deep-Swift hydraulic niche were found for sites near the two farthest downstream bridges near Ashland and at Louisville, but only for low-flow conditions. The Deep-Swift microhabitat was of special interest because it is the preferred hydraulic habitat during the adult life of the endangered pallid sturgeon (Scaphirhynchus albus). Temporal differences in relative cross-sectional areas of the Glide low-flow geomorphic microhabitat that contained the Deep-Swift hydraulic niche also indicated that relative cross-sectional areas of the Glide during the 1951-61 and 1996-2006 water-year periods were lower than during the 1966-76 period. The temporal differences indicated that any significant temporal chang

Spatial-temporal analysis of coherent offshore wind field structures measured by scanning Doppler-lidar

NASA Astrophysics Data System (ADS)

Valldecabres, L.; Friedrichs, W.; von Bremen, L.; Kühn, M.

2016-09-01

An analysis of the spatial and temporal power fluctuations of a simplified wind farm model is conducted on four offshore wind fields data sets, two from lidar measurements and two from LES under unstable and neutral atmospheric conditions. The integral length scales of the horizontal wind speed computed in the streamwise and the cross-stream direction revealed the elongation of the structures in the direction of the mean flow. To analyse the effect of the structures on the power output of a wind turbine, the aggregated equivalent power of two wind turbines with different turbine spacing in the streamwise and cross-stream direction is analysed at different time scales under 10 minutes. The fact of considering the summation of the power of two wind turbines smooths out the fluctuations of the power output of a single wind turbine. This effect, which is stronger with increasing spacing between turbines, can be seen in the aggregation of the power of two wind turbines in the streamwise direction. Due to the anti-correlation of the coherent structures in the cross-stream direction, this smoothing effect is stronger when the aggregated power is computed with two wind turbines aligned orthogonally to the mean flow direction.

Health care system change and the cross-border transfer of ideas: influence of the Dutch model on the 2007 German health reform.

PubMed

Leiber, Simone; Gress, Stefan; Manouguian, Maral-Sonja

2010-08-01

To increase understanding of the cross-border transfer of ideas through a case study of the 2007 German health reform, this article draws on Kingdon's approach of streams and follows two main objectives: first, to understand the extent to which the German health reform was actually influenced by the Dutch model and, second, in theoretical terms, to inform inductively on how ideas from abroad enter government agendas. The results show that the streams of problem recognition and policy proposals have not been predominantly influenced by the cross-border transfer of ideas from the Netherlands to Germany. The Dutch experience was taken into consideration only after a policy window opened by a shift in politics in the third, the political, stream: the change of government in 2005. In many respects, the way Germany learned from the Netherlands in this case sharply contrasts with an image of solving policy problems by either lesson drawing or transnational deliberation. Instead, the process was dominated by problem solving in the sphere of politics, that is, finding a way to prove the grand coalition was capable of acting.

Sediment Mobilization and Storage Dynamics of a Debris Flow Impacted Stream Channel using Multi-Temporal Structure from Motion Photogrammetry

NASA Astrophysics Data System (ADS)

Bailey, T. L.; Sutherland-Montoya, D.

2015-12-01

High resolution topographic analysis methods have become important tools in geomorphology. Structure from Motion photogrammetry offers a compelling vehicle for geomorphic change detection in fluvial environments. This process can produce arbitrarily high resolution, geographically registered spectral and topographic coverages from a collection of overlapping digital imagery from consumer cameras. Cuneo Creek has had three historically observed episodes of rapid aggradation (1955, 1964, and 1997). The debris flow deposits continue to be major sources of sediment sixty years after the initial slope failure. Previous studies have monitored the sediment storage volume and particle size since 1976 (in 1976, 1982, 1983, 1985, 1986, 1987, 1998, 2003). We reoccupied 3 previously surveyed stream cross sections on Sept 30, 2014 and March 30, 2015, and produced photogrammetric point clouds using a pole mounted camera with a remote view finder to take nadir view images from 4.3 meters above the channel bed. Ground control points were registered using survey grade GPS and typical cross sections used over 100 images to build the structure model. This process simultaneously collects channel geometry and we used it to also generate surface texture metrics, and produced DEMs with point cloud densities above 5000 points / m2. In the period between the surveys, a five year recurrence interval discharge of 20 m3/s scoured the channel. Surface particle size distribution has been determined for each observation period using image segmentation algorithms based on spectral distance and compactness. Topographic differencing between the point clouds shows substantial channel bed mobilization and reorganization. The net decline in sediment storage is in excess of 4 x 10^5 cubic meters since the 1964 aggradation peak, with associated coarsening of surface particle sizes. These new methods provide a promising rapid assessment tool for measurement of channel responses to sediment inputs.

Solid medical waste: a cross sectional study of household disposal practices and reported harm in Southern Ghana.

PubMed

Udofia, Emilia Asuquo; Gulis, Gabriel; Fobil, Julius

2017-05-18

Solid medical waste (SMW) in households is perceived to pose minimal risks to the public compared to SMW generated from healthcare facilities. While waste from healthcare facilities is subject to recommended safety measures to minimize risks to human health and the environment, similar waste in households is often untreated and co-mingled with household waste which ends up in landfills and open dumps in many African countries. In Ghana, the management of this potentially hazardous waste stream at household and community level has not been widely reported. The objective of this study was to investigate household disposal practices and harm resulting from SMW generated in households and the community. A cross-sectional questionnaire survey of 600 households was undertaken in Ga South Municipal Assembly in Accra, Ghana from mid-April to June, 2014. Factors investigated included socio-demographic characteristics, medication related practices, the belief that one is at risk of diseases associated with SMW, SMW disposal practices and reported harm associated with SMW at home and in the community. Eighty percent and 89% of respondents discarded unwanted medicines and sharps in household refuse bins respectively. A corresponding 23% and 35% of respondents discarded these items without a container. Harm from SMW in the household and in the community was reported by 5% and 3% of respondents respectively. Persons who believed they were at risk of diseases associated with SMW were nearly three times more likely to report harm in the household (OR 2.75, 95%CI 1.15-6.54). The belief that one can be harmed by diseases associated with SMW influenced reporting rates in the study area. Disposal practices suggest the presence of unwanted medicines and sharps in the household waste stream conferring on it hazardous properties. Given the low rates of harm reported, elimination of preventable harm might justify community intervention.

Collection methods, data compilation, and lessons learned from a study of stream geomorphology associated with riparian cattle grazing along the Fever River, University of Wisconsin- Platteville Pioneer Farm, Wisconsin, 2004–11

USGS Publications Warehouse

Peppler, Marie C.; Fitzpatrick, Faith A.

2018-03-09

Stream geomorphic characteristics were monitored along a 0.8-mile reach of the Fever River in the Driftless Area of southwestern Wisconsin from 2004 to 2011 where cattle grazed in paddocks along the riverbank at the University of Wisconsin-Platteville’s Pioneer Farm. The study reach encompassed seven paddocks that covered a total of 30 acres on both sides of the river. Monitoring data included channel crosssection surveys, eroding bank measurements and photograph points, erosion-pin measurements, longitudinal profile surveys, measurements of the volume of soft sediment in the channel, and repeated time-lapse photographs. Characteristics were summarized into subreaches by use of a geographic information system. From 2004 to 2007, baseline monitoring was done to identify geomorphic conditions prior to evaluating the effects of management alternatives for riparian grazing. Subsequent to the full-scale baseline monitoring, additional data were collected from 2007 to 2011. Samples of eroding bank and in-channel soft sediment were collected and analyzed for dry bulk density in 2008 for use in a sediment budget. One of the pastures was excluded from cattle grazing in the fall of 2007; in 2009 channel cross sections, longitudinal profiles, erosion-pin measurements, photographs, and a soft sediment survey were again collected along the full 0.8-mile reach for a comparison to baseline monitoring data. Channel cross sections were surveyed a final time in 2011. Lessons learned from bank monitoring with erosion pins were most numerous and included the need for consistent tracking of each pin and whether there was deposition or erosion, timing of measurements and bank conditions during measurements (frozen, postflood), and awareness of pins loosening in place. Repeated freezing and thawing of banks and consequential mass wasting and jointing enhance fluvial erosion. Monitoring equipment in the paddocks was kept flush to the ground or located high on posts to avoid injuring the cattle.

Topographic Controls on Hillslope-Riparian Water Table Continuity in a set of Nested Catchments, Northern Rocky Mountains, Montana

NASA Astrophysics Data System (ADS)

Jencso, K. G.; McGlynn, B. L.; Gooseff, M. N.; Wondzell, S. M.; Bencala, K. E.; Payn, R. A.

2007-12-01

Understanding how hillslope and riparian water table dynamics influence catchment scale hydrologic response remains a challenge. In steep headwater catchments with shallow soils, topographic convergence and divergence (upslope accumulated area-UAA) is a hypothesized first-order control on the distribution of soil water and groundwater. To test the relationship between UAA and the longevity of hillslope-riparian-stream shallow groundwater connectivity, we quantified water table continuity based on 80+ recording wells distributed across 24 hillslope-riparian-stream cross-sections. Cross-section upstream catchment areas ranged in size from 0.41 to 17.2 km2, within the Tenderfoot Creek Experimental Forest (U.S. Forest Service), northern Rocky Mountains, Montana, USA. We quantified toe-slope UAA and the topographic index (TI = ln a/tanβ) with a Multiple-D- Infinity (area routing in multiple infinite downslope directions) flow accumulation algorithm analysis of 1, 3, 10, and 30m ALSM derived DEMs. Indices derived from the 10m DEM best characterized subsurface flow accumulation, highlighting the balance between the process of interest, topographic complexity, and optimal grid scale representation. Across the 24 transects, toe-slope UAA ranged from 600-40,000 m2, the TI ranged from 5-16, and riparian widths were between 0-60m. Patterns in shallow groundwater table fluctuations suggest hydrologic dynamics reflective of hillslope-riparian landscape setting. Specifically, correlations were observed between longevity of hillslope-riparian water table continuity and the size of the UAA (r2=0.84) and its topographic index (r2=.86). These observations highlight the temporal component of topographic-hydrologic relationships important for understanding threshold mediated hydrologic variables. We are working to quantify the characteristics and spatial distribution of hillslope-riparian sequences and their water table dynamics to temporally link runoff source areas to whole catchment hydrologic response.

Use of remote sensing to identify spatial risk factors for malaria in a region of declining transmission: a cross-sectional and longitudinal community survey.

PubMed

Moss, William J; Hamapumbu, Harry; Kobayashi, Tamaki; Shields, Timothy; Kamanga, Aniset; Clennon, Julie; Mharakurwa, Sungano; Thuma, Philip E; Glass, Gregory

2011-06-10

The burden of malaria has decreased dramatically within the past several years in parts of sub-Saharan Africa. Further malaria control will require targeted control strategies based on evidence of risk. The objective of this study was to identify environmental risk factors for malaria transmission using remote sensing technologies to guide malaria control interventions in a region of declining burden of malaria. Satellite images were used to construct a sampling frame for the random selection of households enrolled in prospective longitudinal and cross-sectional surveys of malaria parasitaemia in Southern Province, Zambia. A digital elevation model (DEM) was derived from the Shuttle Radar Topography Mission version 3 DEM and used for landscape characterization, including landforms, elevation, aspect, slope, topographic wetness, topographic position index and hydrological models of stream networks. A total of 768 individuals from 128 randomly selected households were enrolled over 21 months, from the end of the rainy season in April 2007 through December 2008. Of the 768 individuals tested, 117 (15.2%) were positive by malaria rapid diagnostic test (RDT). Individuals residing within 3.75 km of a third order stream were at increased risk of malaria. Households at elevations above the baseline elevation for the region were at decreasing risk of having RDT-positive residents. Households where new infections occurred were overlaid on a risk map of RDT positive households and incident infections were more likely to be located in high-risk areas derived from prevalence data. Based on the spatial risk map, targeting households in the top 80th percentile of malaria risk would require malaria control interventions directed to only 24% of the households. Remote sensing technologies can be used to target malaria control interventions in a region of declining malaria transmission in southern Zambia, enabling a more efficient use of resources for malaria elimination.

Visual and visuomotor processing of hands and tools as a case study of cross talk between the dorsal and ventral streams.

PubMed

Almeida, Jorge; Amaral, Lénia; Garcea, Frank E; Aguiar de Sousa, Diana; Xu, Shan; Mahon, Bradford Z; Martins, Isabel Pavão

2018-05-24

A major principle of organization of the visual system is between a dorsal stream that processes visuomotor information and a ventral stream that supports object recognition. Most research has focused on dissociating processing across these two streams. Here we focus on how the two streams interact. We tested neurologically-intact and impaired participants in an object categorization task over two classes of objects that depend on processing within both streams-hands and tools. We measured how unconscious processing of images from one of these categories (e.g., tools) affects the recognition of images from the other category (i.e., hands). Our findings with neurologically-intact participants demonstrated that processing an image of a hand hampers the subsequent processing of an image of a tool, and vice versa. These results were not present in apraxic patients (N = 3). These findings suggest local and global inhibitory processes working in tandem to co-register information across the two streams.

Prediction of static aerodynamic characteristics for slender bodies alone and with lifting surfaces to very high angles of attack

NASA Technical Reports Server (NTRS)

Jorgensen, L. H.

1977-01-01

An engineering-type method is presented for computing normal-force and pitching-moment coefficients for slender bodies of circular and noncircular cross section alone and with lifting surfaces. In this method, a semi-empirical term representing viscous-separation crossflow is added to a term representing potential-theory crossflow. For many bodies of revolution, computed aerodynamic characteristics are shown to agree with measured results for investigated free-stream Mach numbers from 0.6 to 2.9. The angles of attack extend from 0 deg to 180 deg for M = 2.9 from 0 deg to 60 deg for M = 0.6 to 2.0. For several bodies of elliptic cross section, measured results are also predicted reasonably well over the investigated Mach number range from 0.6 to 2.0 and at angles of attack from 0 deg to 60 deg. As for the bodies of revolution, the predictions are best for supersonic Mach numbers. For body-wing and body-wing-tail configurations with wings of aspect ratios 3 and 4, measured normal-force coefficients and centers are predicted reasonably well at the upper test Mach number of 2.0. Vapor-screen and oil-flow pictures are shown for many body, body-wing and body-wing-tail configurations. When spearation and vortex patterns are asymmetric, undesirable side forces are measured for the models even at zero sideslip angle. Generally, the side-force coefficients decrease or vanish with the following: increase in Mach number, decrease in nose fineness ratio, change from sharp to blunt nose, and flattening of body cross section (particularly the body nose).

Effects of slope smoothing in river channel modeling

NASA Astrophysics Data System (ADS)

Kim, Kyungmin; Liu, Frank; Hodges, Ben R.

2017-04-01

In extending dynamic river modeling with the 1D Saint-Venant equations from a single reach to a large watershed there are critical questions as to how much bathymetric knowledge is necessary and how it should be represented parsimoniously. The ideal model will include the detail necessary to provide realism, but not include extraneous detail that should not exert a control on a 1D (cross-section averaged) solution. In a Saint-Venant model, the overall complexity of the river channel morphometry is typically abstracted into metrics for the channel slope, cross-sectional area, hydraulic radius, and roughness. In stream segments where cross-section surveys are closely spaced, it is not uncommon to have sharp changes in slope or even negative values (where a positive slope is the downstream direction). However, solving river flow with the Saint-Venant equations requires a degree of smoothness in the equation parameters or the equation set with the directly measured channel slopes may not be Lipschitz continuous. The results of non-smoothness are typically extended computational time to converge solutions (or complete failure to converge) and/or numerical instabilities under transient conditions. We have investigated using cubic splines to smooth the bottom slope and ensure always positive reference slopes within a 1D model. This method has been implemented in the Simulation Program for River Networks (SPRNT) and is compared to the standard HEC-RAS river solver. It is shown that the reformulation of the reference slope is both in keeping with the underlying derivation of the Saint-Venant equations and provides practical numerical stability without altering the realism of the simulation. This research was supported in part by the National Science Foundation under grant number CCF-1331610.

Determination of hyporheic travel time distributions and other parameters from concurrent conservative and reactive tracer tests by local-in-global optimization

NASA Astrophysics Data System (ADS)

Knapp, Julia L. A.; Cirpka, Olaf A.

2017-06-01

The complexity of hyporheic flow paths requires reach-scale models of solute transport in streams that are flexible in their representation of the hyporheic passage. We use a model that couples advective-dispersive in-stream transport to hyporheic exchange with a shape-free distribution of hyporheic travel times. The model also accounts for two-site sorption and transformation of reactive solutes. The coefficients of the model are determined by fitting concurrent stream-tracer tests of conservative (fluorescein) and reactive (resazurin/resorufin) compounds. The flexibility of the shape-free models give rise to multiple local minima of the objective function in parameter estimation, thus requiring global-search algorithms, which is hindered by the large number of parameter values to be estimated. We present a local-in-global optimization approach, in which we use a Markov-Chain Monte Carlo method as global-search method to estimate a set of in-stream and hyporheic parameters. Nested therein, we infer the shape-free distribution of hyporheic travel times by a local Gauss-Newton method. The overall approach is independent of the initial guess and provides the joint posterior distribution of all parameters. We apply the described local-in-global optimization method to recorded tracer breakthrough curves of three consecutive stream sections, and infer section-wise hydraulic parameter distributions to analyze how hyporheic exchange processes differ between the stream sections.

Fluid Mechanics and Heat Transfer in Transitional Boundary Layers

NASA Technical Reports Server (NTRS)

Wang, Ting

2007-01-01

Experiments have been performed to investigate the effects of elevated free-stream turbulence and streamwise acceleration on flow and thermal structures in transitional boundary layers. The free-stream turbulence ranges from 0.5 to 6.4% and the streamwise acceleration ranges from K = 0 to 0.8 x 10(exp -6). The onset of transition, transition length and the turbulent spot formation rate are determined. The statistical results and conditionally sampled results of th streamwise and cross-stream velocity fluctuations, temperature fluctuations, Reynolds stress and Reynolds heat fluxes are presented.

40 CFR 65.149 - Boilers and process heaters.

Code of Federal Regulations, 2010 CFR

2010-07-01

... stream is not introduced as or with the primary fuel, a temperature monitoring device in the fire box...-throughput transfer racks, as applicable, shall meet the requirements of this section. (2) The vent stream... thermal units per hour) or greater. (ii) A boiler or process heater into which the vent stream is...

A Dualistic Stream Classification System for Oregon: In Support of a Stream Compensatory Mitigation Framework

EPA Science Inventory

To meet the goals of the U.S. federal Clean Water Act (CWA) and Oregon’s Removal-Fill (R-F) Law, unavoidable impacts to jurisdictional waters, including streams and rivers, must be compensated for through compensatory mitigation under the CWA Section 404 and R-F permitting ...

40 CFR 63.138 - Process wastewater provisions-performance standards for treatment processes managing Group 1...

Code of Federal Regulations, 2012 CFR

2012-07-01

... each treatment process. (b) Control options: Group 1 wastewater streams for Table 9 compounds. The... section. (c) Control options: Group 1 wastewater streams for Table 8 compounds. The owner or operator...) Residuals. For each residual removed from a Group 1 wastewater stream, the owner or operator shall control...

40 CFR 63.138 - Process wastewater provisions-performance standards for treatment processes managing Group 1...

Code of Federal Regulations, 2013 CFR

2013-07-01

... each treatment process. (b) Control options: Group 1 wastewater streams for Table 9 compounds. The... section. (c) Control options: Group 1 wastewater streams for Table 8 compounds. The owner or operator...) Residuals. For each residual removed from a Group 1 wastewater stream, the owner or operator shall control...

40 CFR 63.138 - Process wastewater provisions-performance standards for treatment processes managing Group 1...

Code of Federal Regulations, 2011 CFR

2011-07-01

... each treatment process. (b) Control options: Group 1 wastewater streams for Table 9 compounds. The... section. (c) Control options: Group 1 wastewater streams for Table 8 compounds. The owner or operator...) Residuals. For each residual removed from a Group 1 wastewater stream, the owner or operator shall control...

Strong wave/mean-flow coupling in baroclinic acoustic streaming

NASA Astrophysics Data System (ADS)

Chini, Greg; Michel, Guillaume

2017-11-01

Recently, Chini et al. demonstrated the potential for large-amplitude acoustic streaming in compressible channel flows subjected to strong background cross-channel density variations. In contrast with classic Rayleigh streaming, standing acoustic waves of O (ɛ) amplitude acquire vorticity owing to baroclinic torques acting throughout the domain rather than via viscous torques acting in Stokes boundary layers. More significantly, these baroclinically-driven streaming flows have a magnitude that also is O (ɛ) , i.e. comparable to that of the sound waves. In the present study, the consequent potential for fully two-way coupling between the waves and streaming flows is investigated using a novel WKBJ analysis. The analysis confirms that the wave-driven streaming flows are sufficiently strong to modify the background density gradient, thereby modifying the leading-order acoustic wave structure. Simulations of the wave/mean-flow system enabled by the WKBJ analysis are performed to illustrate the nature of the two-way coupling, which contrasts sharply with classic Rayleigh streaming, for which the waves can first be determined and the streaming flows subsequently computed.

Transient storage assessments of dye-tracer injections in rivers of the Willamette Basin, Oregon

USGS Publications Warehouse

Laenen, A.; Bencala, K.E.

2001-01-01

Rhodamine WT dye-tracer injections in rivers of the Willamette Basin yield concentration-time curves with characteristically long recession times suggestive of active transient storage processes. The scale of drainage areas contributing to the stream reaches studied in the Willamette Basin ranges from 10 to 12,000 km2. A transient storage assessment of the tracer studies has been completed using the U.S. Geological Survey's One-dimensional Transport with Inflow and Storage (OTIS) model, which incorporates storage exchange and decay functions along with the traditional dispersion and advection transport equation. The analysis estimates solute transport of the dye. It identifies first-order decay coefficients to be on the order of 10-5/sec for the nonconservative Rhodamine WT. On an individual subreach basis, the first-order decay is slower (typically by an order of magnitude) than the transient storage process, indicating that nonconservative tracers may be used to evaluate transient storage in rivers. In the transient storage analysis, a dimensionless parameter (As/A) expresses the spatial extent of storage zone area relative to stream cross section. In certain reaches of Willamette Basin pool-and-riffle, gravel-bed rivers, this parameter was as large as 0.5. A measure of the storage exchange flux was calculated for each stream subreach in the simulation analysis. This storage exchange is shown subjectively to be higher at higher stream discharges. Hyporheic linkage between streams and subsurface flows is the probable physical mechanism contributing to a significant part of this inferred active transient storage. Hyporheic linkages are further suggested by detailed measurements of river discharge with an Acoustic Doppler Current Profiler system delineating zones in two large rivers where water alternately enters and leaves the surface channels through graveland-cobble riverbeds. Measurements show patterns of hyporheic exchange that are highly variable in time and space.

Evaluation of Uncertainty in Bedload Transport Estimates in a Southern Appalachian Stream

NASA Astrophysics Data System (ADS)

Schwartz, J. S.

2016-12-01

Capacity estimates of bed-material transport rates are generally derived using empirical formulae as a function of bed material gradation and composition, and hydraulic shear stress. Various field techniques may be used to sample and characterize bed material gradation; some techniques assume the existing bar material is representative of that in transport. Other methods use Helly-Smith samplers, pit traps, and net traps. Very few large, complete cross-section pit traps fully instrumented to collect continuous bedload transport have been constructed, and none in the eastern United States to our knowledge. A fully-instrumented bedload collection station was constructed on Little Turkey Creek (LTC) in Farragut, Tennessee. The aim of the research was to characterize bed material transport during stormflows for a southern Appalachian stream in the Ridge and Valley Providence. Bedload transport data from LTC was compared with classic datasets including Oak Creek (Oregon), East Fork River (Wyoming), and Clearwater and Snake rivers (Idaho). In addition, data were evaluated to assess the potential accuracy of both calibrated and uncalibrated bedload transport models using bedload transport data from LTC. Uncalibrated models were assessed with regard to their estimated range of uncertainty according to Monte Carlo uncertainty analyses. Models calibrated using reference shear values determined according to station measurements are evaluated in the same manner. Finally, models calibrated using the small scale, short-term, low rate bedload sampling techniques promoted in the literature for the spreadsheet based Bedload Assessment in Gravel-bedded Streams (BAGS) software for determining the reference shear stress are compared to results of both uncalibrated models and those calibrated using data from the bedload station. This research supports design and construction of dynamically stable alluvial stream restoration projects where stream channels are largely dependent on reach-scale hydraulic geometry that provides a long-term balance between bed-material sediment supply and transport capacity.

Geomorphic effects of rural-to-urban land use conversion on three streams in the Central Redbed Plains of Oklahoma

NASA Astrophysics Data System (ADS)

Kang, Ranbir S.; Marston, Richard A.

2006-09-01

This research evaluates the impact of rural-to-urban land use conversion on channel morphology and riparian vegetation for three streams in the Central Redbed Plains geomorphic province (central Great Plains ecoregion) of Oklahoma. The Deep Fork Creek watershed is largely urbanized; the Skeleton Creek watershed is largely rural; and the Stillwater Creek watershed is experiencing a rapid transition from rural to urban land cover. Each channel was divided into reaches based on tributary junctions, sinuosity, and slope. Field surveys were conducted at transects in a total of 90 reaches, including measurements of channel units, channel cross-section at bankfull stage, and riparian vegetation. Historical aerial photographs were available for only Stillwater Creek watershed, which were used to document land cover in this watershed, especially changes in the extent of urban areas (impervious cover). The three streams have very low gradients (< 0.001), width-to-depth ratios < 10, and cohesive channel banks, but have incised into red Permian shales and sandstone. The riparian vegetation is dominated by cottonwoods, ash, and elm trees that provide a dense root mat on stream banks where the riparian vegetation is intact. Channels increased in width and depth in the downstream direction as is normally expected, but the substrate materials and channel units remained unchanged. Statistical analyses demonstrated that urbanization did not explain spatial patterns of changes in any variables. These three channels in the central Redbed Plains are responding as flumes during peak flows, funneling runoff and the wash-load sediment downstream in major runoff events without any effect on channel dimensions. Therefore, local geological conditions (similar bedrock, cohesive substrates and similar riparian vegetation) are mitigating the effects of urbanization.

Dye laser amplifier including an improved window configuration for its dye beam

DOEpatents

O'Neil, R.W.; Davin, J.M.

1992-12-01

A dye laser amplifier in which a continuously replenished supply of dye is excited with a first light beam in order to amplify the intensity of a second different light beam passing therethrough is disclosed herein. This amplifier includes a cell though which a continuous stream of the dye is caused to pass, and means for directing the first beam into the cell while the second beam is directed into and through the same cell. There is also disclosed herein a specific improvement to this amplifier which resides in the use of a pair of particularly configured windows through which the second beam passes along fixed paths as the second beam enters and exits the dye cell. Each of these windows has a relatively thick main section which is substantially larger in dimensions transverse to its beam path than the cross section of the second beam itself, whereby to add structural integrity to the overall window. At the same time, the latter includes a second section which is disposed entirely within the confines of the main section and through which the second beam is intended to pass in its entirety. This second section is made substantially thinner than the main section in order to reduce optical distortion as the second beam passes therethrough. 4 figs.

Dye laser amplifier including an improved window configuration for its dye beam

DOEpatents

O'Neil, Richard W.; Davin, James M.

1992-01-01

A dye laser amplifier in which a continuously replenished supply of dye is excited with a first light beam in order to amplify the intensity of a second different light beam passing therethrough is disclosed herein. This amplifier includes a cell though which a continuous stream of the dye is caused to pass, and means for directing the first beam into the cell while the second beam is directed into and through the same cell. There is also disclosed herein a specific improvement to this amplifier which resides in the use of a pair of particularly configured windows through which the second beam passes along fixed paths as the second beam enters and exits the dye cell. Each of these windows has a relatively thick main section which is substantially larger in dimensions transverse to its beam path than the cross section of the second beam itself, whereby to add structural integrity to the overall window. At the same time, the latter includes a second section which is disposed entirely within the confines of the main section and through which the second beam is intended to pass in its entirety. This second section is made substantially thinner than the main section in order to reduce optical distortion as the second beam passes therethrough.

Proceedings of the 1998 Migrant Farmworker Stream Forums: Annual Midwest Farmworker Stream Forum (8th, San Antonio, Texas, November 5-8, 1998); Annual East Coast Migrant Stream Forum (11th, Springfield, Massachusetts, November 13-15, 1998); Annual Western Migrant Stream Forum (8th, Sacramento, California, January 29-31, 1999).

ERIC Educational Resources Information Center

National Center for Farmworker Health, Inc., Austin, TX.

Researchers, advocates, and clinicians met at the three 1998 migrant stream forums to develop strategies for farmworker health research. The introductory section of this proceedings discusses this year's focus--building research partnerships to improve migrant health--and describes planning and implementation of the forums' research track.…

30 CFR 816.151 - Primary roads.

Code of Federal Regulations, 2013 CFR

2013-07-01

..., or greater event as specified by the regulatory authority; (2) Drainage pipes and culverts shall be... drainage over the road surface and embankment; (4) Culverts shall be installed and maintained to sustain... intermittent stream channel crossings shall be made using bridges, culverts, low-water crossings, or other...

30 CFR 816.151 - Primary roads.

Code of Federal Regulations, 2012 CFR

2012-07-01

..., or greater event as specified by the regulatory authority; (2) Drainage pipes and culverts shall be... drainage over the road surface and embankment; (4) Culverts shall be installed and maintained to sustain... intermittent stream channel crossings shall be made using bridges, culverts, low-water crossings, or other...

30 CFR 816.151 - Primary roads.

Code of Federal Regulations, 2014 CFR

2014-07-01

..., or greater event as specified by the regulatory authority; (2) Drainage pipes and culverts shall be... drainage over the road surface and embankment; (4) Culverts shall be installed and maintained to sustain... intermittent stream channel crossings shall be made using bridges, culverts, low-water crossings, or other...

Fish passage at road crossings: an annotated bibliography.

Treesearch

Lynette Anderson; Mason Bryant

1980-01-01

A report of special interest to fishery biologists, resource managers, hydrologists, and road engineers, this bibliography lists publications pertinent to road crossings of salmon and trout streams. Topics include bridge and culvert installation, design criteria, mechanics, hydraulics, and economics, as well as their biological effects.

X-DRAIN and XDS: a simplified road erosion prediction method

Treesearch

William J. Elliot; David E. Hall; S. R. Graves

1998-01-01

To develop a simple road sediment delivery tool, the WEPP program modeled sedimentation from forest roads for more than 50,000 combinations of distance between cross drains, road gradient, soil texture, distance from stream, steepness of the buffer between the road and the stream, and climate. The sediment yield prediction from each of these runs was stored in a data...

Effect of incubation temperature on post-embryonic survival and growth of steelhead in a natural stream and a hatchery (Study sites: Dworshak Hatchery and North Fork Palouse River; Stocks: Dworshak hatchery; Year classes: 1994 and 1995): Chapter 5

USGS Publications Warehouse

Rubin, Stephen P.; Reisenbichler, Reginald R.; Wetzel, Lisa A.; Stenberg, Karl D.; Baker, Bruce M.; Rubin, Stephen P.; Reisenbichler, Reginald R.; Wetzel, Lisa A.; Hayes, Michael C.

2012-01-01

We tested whether varying incubation temperatures to match development between embryos from different spawning dates affected survival and growth of unfed steelhead Oncorhynchus mykiss fry released in a stream and in hatchery ponds. Hatchery steelhead returning to the Clearwater River, Idaho were artificially spawned on two dates separated by a four week interval. Progeny from the early date (ExE, from early males and early females) were incubated in chilled (7°C) water and those from the late date (LxL) in ambient (12°C) water until developmental stage matched. A third group, created by fertilizing eggs from late females with cryopreserved milt from early males (ExL), was included to control for any genetic differences between early and late returning adults. Survival in the stream to 3 and 15 months after release was similar among crosses. Survival in the hatchery to near the end of the standard one year rearing period was similar among crosses for one of two year - classes but different for the other; however, it was difficult to ascribe the differences (ExL>ExE; LxL intermediate but closer to ExE) to incubation temperature differences. We conclude that there was little if any effect of incubation temperature on survival. Length of juveniles of one year - class differed among crosses in the stream and in the hatchery. Length of the other year - class differed among crosses in one pond at the hatchery but not in the other pond or in the stream. When length differed the pattern was always the same: ExE>LxL; ExL intermediate but closer to LxL. We speculate that incubation temperature may have affected growth of juveniles, and in particular that a longer period of incubation in chilled water may have caused fast juvenile growth relative to a shorter incubation period in ambient water.

Sediment concentration and turbidity changes during culvert removals.

PubMed

Foltz, Randy B; Yanosek, Kristina A; Brown, Timothy M

2008-05-01

The concentrations of sediment and turbidity in stream water were monitored during culvert removals to determine the short term effects of road obliteration. Sediment concentration was measured at 11 stream crossings among two locations in Idaho and one in Washington. Sediment concentration immediately below the culvert outlet exceeded levels above the culvert outlet by at least three orders of magnitude at all stream crossings. Sediment yields ranged from 170 to less than 1kg in the 24-h period following culvert removal. Turbidity exceeded the regulatory limits during culvert removal at all locations monitored in this study and remained above the limits beyond the monitoring periods of 24h at four of the locations. Sediment concentrations 100m downstream of the culvert outlet were reduced by an order of magnitude, but did not change the turbidity values sufficiently to meet regulatory limits. Sediment concentrations an average of 810m downstream of the culvert outlet were similar to sediment concentrations above the culvert for the entire excavation period and turbidity regulations were met. Mitigation consisting of two straw bales placed in the stream caused a significant reduction in sediment yield from an average of 67kg to an average of 1.6kg.

Stream Mitigation Protocol Compendium - 2004

EPA Pesticide Factsheets

This document is intended as a reference in order to select, adapt, or devise stream assessment methods appropriate for impact assessment and mitigation of fluvial resources in the CWA Section 404 Program.

Hydraulic-Geometry Relations for Rivers in Coastal and Central Maine

USGS Publications Warehouse

Dudley, Robert W.

2004-01-01

Hydraulic-geometry relations (curves) were derived for 15 sites on 12 rivers in coastal and central Maine on the basis of site-specific (at-a-station) hydraulic-geometry relations and hydraulic models. At-a-station hydraulic-geometry curves, expressed as well-established power functions, describe the relations between channel geometry, velocity, and flow at a given point on a river. The derived at-a-station hydraulic-geometry curves indicate that, on average, a given increase in flow at a given river cross section in the study area will be nearly equally conveyed by increases in velocity and channel cross-sectional area. Regional curves describing the bankfull streamflow and associated channel geometry as functions of drainage area were derived for use in stream-channel assessment and restoration projects specific to coastal and central Maine. Regional hydraulic-geometry curves were derived by combining hydraulic-geometry information for 15 river cross sections using bankfull flow as the common reference streamflow. The exponents of the derived regional hydraulic-geometry relations indicate that, in the downstream direction, most of the conveyance of increasing contribution of flow is accommodated by an increase in cross-sectional area?with about 50 percent of the increase in flow accommodated by an increase in channel width, and 32 percent by an increase in depth. The remaining 18 percent is accommodated by an increase in streamflow velocity. On an annual-peak-series basis, results of this study indicate that the occurrence of bankfull streamflow for rivers in Maine is more frequent than the 1.5-year streamflow. On a flow-duration basis, bankfull streamflow for rivers in coastal and central Maine is equaled or exceeded approximately 8.1 percent of the time on mean?or about 30 days a year. Bankfull streamflow is roughly three times that of the mean annual streamflow for the sites investigated in this study. Regional climate, snowmelt hydrology, and glacial geology may play important roles in dictating the magnitude and frequency of occurrence of bankfull streamflows observed for rivers in coastal and central Maine.

Cattle-derived microbial input to source water catchments: An experimental assessment of stream crossing modification.

PubMed

Smolders, Andrew; Rolls, Robert J; Ryder, Darren; Watkinson, Andrew; Mackenzie, Mark

2015-06-01

The provision of safe drinking water is a global issue, and animal production is recognized as a significant potential origin of human infectious pathogenic microorganisms within source water catchments. On-farm management can be used to mitigate livestock-derived microbial pollution in source water catchments to reduce the risk of contamination to potable water supplies. We applied a modified Before-After Control Impact (BACI) design to test if restricting the access of livestock to direct contact with streams prevented longitudinal increases in the concentrations of faecal indicator bacteria and suspended solids. Significant longitudinal increases in pollutant concentrations were detected between upstream and downstream reaches of the control crossing, whereas such increases were not detected at the treatment crossing. Therefore, while the crossing upgrade was effective in preventing cattle-derived point source pollution by between 112 and 158%, diffuse source pollution to water supplies from livestock is not ameliorated by this intervention alone. Our findings indicate that stream crossings that prevent direct contact between livestock and waterways provide a simple method for reducing pollutant loads in source water catchments, which ultimately minimises the likelihood of pathogenic microorganisms passing through source water catchments and the drinking water supply system. The efficacy of the catchment as a primary barrier to pathogenic risks to drinking water supplies would be improved with the integration of management interventions that minimise direct contact between livestock and waterways, combined with the mitigation of diffuse sources of livestock-derived faecal matter from farmland runoff to the aquatic environment. Copyright © 2015 Elsevier Ltd. All rights reserved.

Calibration of a transient transport model to tritium data in streams and simulation of groundwater ages in the western Lake Taupo catchment, New Zealand

NASA Astrophysics Data System (ADS)

Gusyev, M. A.; Toews, M.; Morgenstern, U.; Stewart, M.; White, P.; Daughney, C.; Hadfield, J.

2013-03-01

Here we present a general approach of calibrating transient transport models to tritium concentrations in river waters developed for the MT3DMS/MODFLOW model of the western Lake Taupo catchment, New Zealand. Tritium has a known pulse-shaped input to groundwater systems due to the bomb tritium in the early 1960s and, with its radioactive half-life of 12.32 yr, allows for the determination of the groundwater age. In the transport model, the tritium input (measured in rainfall) passes through the groundwater system, and the simulated tritium concentrations are matched to the measured tritium concentrations in the river and stream outlets for the Waihaha, Whanganui, Whareroa, Kuratau and Omori catchments from 2000-2007. For the Kuratau River, tritium was also measured between 1960 and 1970, which allowed us to fine-tune the transport model for the simulated bomb-peak tritium concentrations. In order to incorporate small surface water features in detail, an 80 m uniform grid cell size was selected in the steady-state MODFLOW model for the model area of 1072 km2. The groundwater flow model was first calibrated to groundwater levels and stream baseflow observations. Then, the transient tritium transport MT3DMS model was matched to the measured tritium concentrations in streams and rivers, which are the natural discharge of the groundwater system. The tritium concentrations in the rivers and streams correspond to the residence time of the water in the groundwater system (groundwater age) and mixing of water with different age. The transport model output showed a good agreement with the measured tritium values. Finally, the tritium-calibrated MT3DMS model is applied to simulate groundwater ages, which are used to obtain groundwater age distributions with mean residence times (MRTs) in streams and rivers for the five catchments. The effect of regional and local hydrogeology on the simulated groundwater ages is investigated by demonstrating groundwater ages at five model cross-sections to better understand MRTs simulated with tritium-calibrated MT3DMS and lumped parameter models.

Fluvial wood function downstream of beaver versus man-made dams in headwater streams in Massachusetts, USA

NASA Astrophysics Data System (ADS)

David, G. C.; DeVito, L. F.; Munz, K. T.; Lisius, G.

2014-12-01

Fluvial wood is an essential component of stream ecosystems by providing habitat, increasing accumulation of organic matter, and increasing the processing of nutrients and other materials. However, years of channel alterations in Massachusetts have resulted in low wood loads despite the afforestation that has occurred since the early 1900s. Streams have also been impacted by a large density of dams, built during industrialization, and reduction of the beaver population. Beavers were reintroduced to Massachusetts in the 1940s and they have since migrated throughout the state. Beaver dams impound water, which traps sediment and results in the development of complex channel patterns and more ecologically productive and diverse habitats than those found adjacent to man-made dams. To develop better management practices for dam removal it is essential that we understand the geomorphic and ecologic function of wood in these channels and the interconnections with floodplain dynamics and stream water chemistry. We investigate the connections among fluvial wood, channel morphology, floodplain soil moisture dynamics, and stream water chemistry in six watersheds in Massachusetts that have been impacted by either beaver or man-made dams. We hypothesize that wood load will be significantly higher below beaver dams, subsequently altering channel morphology, water chemistry, and floodplain soil moisture. Reaches are surveyed up- and downstream of each type of dam to better understand the impact dams have on the fluvial system. Surveys include a longitudinal profile, paired with dissolved oxygen and ammonium measurements, cross-section and fluvial wood surveys, hydraulic measurements, and floodplain soil moisture mapping. We found that dissolved oxygen mirrored the channel morphology, but did not vary significantly between reaches. Wood loads were significantly larger downstream of beaver dams, which resulted in significant changes to the ammonium levels. Floodplain soil moisture dynamics revealed that wood loads increased the channel complexity and strengthened connections between the stream channel and floodplain. Future work will continue to explore the complex interconnections between beaver dams, channel morphology, hydraulics, floodplain dynamics and water chemistry.

Electrokinetic flow in a capillary with a charge-regulating surface polymer layer.

PubMed

Keh, Huan J; Ding, Jau M

2003-07-15

An analytical study of the steady electrokinetic flow in a long uniform capillary tube or slit is presented. The inside wall of the capillary is covered by a layer of adsorbed or covalently bound charge-regulating polymer in equilibrium with the ambient electrolyte solution. In this solvent-permeable and ion-penetrable surface polyelectrolyte layer, ionogenic functional groups and frictional segments are assumed to distribute at uniform densities. The electrical potential and space charge density distributions in the cross section of the capillary are obtained by solving the linearized Poisson-Boltzmann equation. The fluid velocity profile due to the application of an electric field and a pressure gradient through the capillary is obtained from the analytical solution of a modified Navier-Stokes/Brinkman equation. Explicit formulas for the electroosmotic velocity, the average fluid velocity and electric current density on the cross section, and the streaming potential in the capillary are also derived. The results demonstrate that the direction of the electroosmotic flow and the magnitudes of the fluid velocity and electric current density are dominated by the fixed charge density inside the surface polymer layer, which is determined by the regulation characteristics such as the dissociation equilibrium constants of the ionogenic functional groups in the surface layer and the concentration of the potential-determining ions in the bulk solution.

Foothills Parkway Section 8B Final Environmental Report, Volume 3, Appendix D

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blasing, T.J.; Cada, G.F.; Carer, M.

1999-07-01

In 1994, Oak Ridge National Laboratory (ORNL) was tasked by the National Park Service (NPS) to prepare an Environmental Report (ER) for Section 8B of the Foothills Parkway in the Great Smoky Mountains National Park (GSMNP). Section 8B represents 27.7 km (14.2 miles) of a total of 115 km (72 miles) of the planned Foothills Parkway and would connect the Cosby community on the east to the incorporated town of Pittman Center to the west. The major deliverables for the project are listed. From August 1995 through October 1996, NPS, GSMNP, and ORNL staff interacted with Federal Highway Administration staffmore » to develop a conceptual design plan for Section 8B with the intent of protecting critical resources identified during the ER process to the extent possible. In addition, ORNL arranged for bioengineering experts to discuss techniques that might be employed on Section 8B with NPS, GSMNP, and ORNL staff during September 1996. For the purposes of this ER, there are two basic alternatives under consideration: (1) a build alternative and (2) a no-build alternative. Within the build alternative are a number of options including constructing Section 8B with no interchanges, constructing Section 8B with an interchange at SR416 or U.S. 321, constructing Section 8B with a spur road on Webb Mountain, and considering operation of Section 8B both before and after the operation of Section 8C. The no-build alternative is considered the no-action alternative and is not to construct Section 8B. This volume of the ER inventories the fishes and benthic macroinvertebrates inhabiting the aquatic ecosystems potentially affected by the proposed construction of Section 8B. Stream biological surveys were completed at 31 stream sites during the Fall of 1994. The sampling strategy for both invertebrates and fish was to survey the different taxa from all available habitats. For benthic invertebrates, a standardized qualitative manual collection technique was employed for all 31 stations. For fish, all streams of sufficient water were sampled using various methods of electroshocking. Two listed species were identified during the surveys: the Allegheny snaketail dragonfly (formerly a C2 federal candidate species found at six of the stream survey sites) and the tangerine darter (a Tennessee state special concern species found at two of the stream survey sites).« less

Tidal streams from axion miniclusters and direct axion searches

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tinyakov, Peter; Tkachev, Igor; Zioutas, Konstantin, E-mail: petr.tiniakov@ulb.ac.be, E-mail: tkachev@inr.ru, E-mail: konstantin.zioutas@cern.ch

In some axion dark matter models a dominant fraction of axions resides in dense small-scale substructures, axion miniclusters. A fraction of these substructures is disrupted and forms tidal streams where the axion density may still be an order of magnitude larger than the average. We discuss implications of these streams for the direct axion searches. We estimate the fraction of disrupted miniclusters and the parameters of the resulting streams, and find that stream-crossing events would occur at a rate of about 1/(20 yr) for 2–3 days, during which the signal in axion detectors would be amplified by a factor ∼ 10. Thesemore » estimates suggest that the effect of the tidal disruption of axion miniclusters may be important for direct axion searches and deserves a more thorough study.« less

Evidence of damage to pink salmon inhabiting Prince William Sound, Alaska, three generations after the Exxon Valdez oil spill

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bue, B.G.; Miller, G.D.; Seeb, J.E.

1995-12-31

Investigations into the environmental effects of the 1 989 Exxon Valdez oil spill lead us to conclude that chronic damage occurred in some pink salmon populations. Differences in survival between streams contaminated by oil and uncontaminated streams have been observed annually since the spill for pink salmon embryos incubating in the intertidal portions of Prince William Sound. The authors assessed the environmental influence on these findings by collecting gametes from both contaminated and uncontaminated streams, transporting them to a hatchery where intra-stream crosses were made, and incubating the resulting embryos under identical conditions. Lower survival was detected in the embryosmore » originating from the oil-contaminated streams indicating that the agent responsible for the differences detected in the field was genetic rather than environmental.« less

Variations in fluvial deposition on an alluvial plain: an example from the Tongue River Member of the Fort Union Formation (Paleocene), southeastern Powder River Basin, Wyoming, U.S.A.

USGS Publications Warehouse

Johnson, E.A.; Pierce, F.W.

1990-01-01

The Tongue River Member of the Paleocene Fort Union Formation is an important coal-bearing sedimentary unit in the Powder River Basin of Wyoming and Montana. We studied the depositional environments of a portion of this member at three sites 20 km apart in the southeastern part of the basin. Six lithofacies are recognized that we assign to five depositional facies categorized as either channel or interchannel-wetlands environments. (1) Type A sandstone is cross stratified and occurs as lenticular bodies with concave-upward basal surfaces; these bodies are assigned to the channel facies interpreted to be the product of low-sinuosity streams. (2) Type B sandstone occurs in parallel-bedded units containing mudrock partings and fossil plant debris; these units constitute the levee facies. (3) Type C sandstone typically lacks internal structure and occurs as tabular bodies separating finer grained deposits; these bodies represent the crevasse-splay facies. (4) Gray mudrock is generally nonlaminated and contains ironstone concretions; these deposits constitute the floodplain facies. (5) Carbonaceous shale and coal are assigned to the swamp facies. We recognize two styles of stream deposition in our study area. Laterally continuous complexes of single and multistoried channel bodies occur at our middle study site and we interpret these to be the deposits of sandy braided stream systems. In the two adjacent study sites, single and multistoried channel bodies are isolated in a matrix of finer-grained interchannel sediment suggesting deposition by anastomosed streams. A depositional model for our study area contains northwest-trending braided stream systems. Avulsions of these systems created anastomosed streams that flowed into adjacent interchannel areas. We propose that during late Paleocene a broad alluvial plain existed on the southeastern flank of the Powder River Basin. The braided streams that crossed this surface were tributaries to a northward-flowing, basin-axis trunk stream that existed to the west. ?? 1990.

In situ dust measurements by the Cassini Cosmic Dust Analyzer in 2014 and beyond

NASA Astrophysics Data System (ADS)

Srama, R.

2015-10-01

Today, the German-lead Cosmic Dust Analyser (CDA) is operated continuously for 11 years in orbit around Saturn. Many discoveries like the Saturn nanodust streams or the large extended Ering were achieved. CDA provided unique results regarding Enceladus, his plume and the liquid water below the icy crust. In 2014 and 2015 CDA focuses on extended inclination and equatorial scans of the ring particle densities. Furthermore, scans are performed of the Pallene and Helene regions. Special attention is also given to the search of the dust cloud around Dione and to the Titan region. Long integration times are needed in order to characterize the flux and composition of exogenous dust (including interstellar dust) or possible retrograde dust particles. Finally, dedicated observation campaigns focus on the coupling of nanodust streams to Saturn's magnetosphere and the search of possible periodicities in the stream data. Saturn's rotation frequency was identified in the impact rate of nanodust particles at a Saturn distance of 40 Saturn radii. A special geometry in 2014-065 lead to an occultation of the dust stream by the moon Titan and its atmosphere when Titan crossed the line-of-sight between Saturn and Cassini. Here, CDA pointed towards Saturn for the measurement of stream particles. Around closest approach when Cassini was behind Titan, the flux of stream particles went down to zero (Fig. 1). This "dust occultation" is a new method to analyse the properties of the stream particles (speed, composition, mass) or the properties of Titans atmosphere (density). Furthermore, the particle trajectories can be constrained for a better analysis of their origin. In the final three years CDA performs exogenous and interstellar dust campaigns, studies of the composition and origin of Saturn's main rings by unique ring ejecta measurements, long-duration nano-dust stream observations, high-resolution maps of small moon orbit crossings, studies of the dust cloud around Dione and studies of the E-ring interaction with the large moon Titan.

Responses to riparian restoration in the Spring Creek watershed, Central Pennsylvania

USGS Publications Warehouse

Carline, R.F.; Walsh, M.C.

2007-01-01

Riparian treatments, consisting of 3- to 4-m buffer strips, stream bank stabilization, and rock-lined stream crossings, were installed in two streams with livestock grazing to reduce sediment loading and stream bank erosion. Cedar Run and Slab Cabin Run, the treatment streams, and Spring Creek, an adjacent reference stream without riparian grazing, were monitored prior to (1991-1992) and 3-5 years after (2001-2003) riparian buffer installation to assess channel morphology, stream substrate composition, suspended sediments, and macroinvertebrate communities. Few changes were found in channel widths and depths, but channel-structuring flow events were rare in the drought period after restoration. Stream bank vegetation increased from 50% or less to 100% in nearly all formerly grazed riparian buffers. The proportion of fine sediments in stream substrates decreased in Cedar Run but not in Slab Cabin Run. After riparian treatments, suspended sediments during base flow and storm flow decreased 47-87% in both streams. Macroinvertebrate diversity did not improve after restoration in either treated stream. Relative to Spring Creek, macroinvertebrate densities increased in both treated streams by the end of the posttreatment sampling period. Despite drought conditions that may have altered physical and biological effects of riparian treatments, goals of the riparian restoration to minimize erosion and sedimentation were met. A relatively narrow grass buffer along 2.4 km of each stream was effective in improving water quality, stream substrates, and some biological metrics. ?? 2007 Society for Ecological Restoration International.

Navier-Stokes analysis and experimental data comparison of compressible flow within ducts

NASA Technical Reports Server (NTRS)

Harloff, G. J.; Reichert, B. A.; Sirbaugh, J. R.; Wellborn, S. R.

1992-01-01

Many aircraft employ ducts with centerline curvature or changing cross-sectional shape to join the engine with inlet and exhaust components. S-ducts convey air to the engine compressor from the intake and often decelerate the flow to achieve an acceptable Mach number at the engine compressor by increasing the cross-sectional area downstream. Circular-to-rectangular transition ducts are used on aircraft with rectangular exhaust nozzles to connect the engine and nozzle. To achieve maximum engine performance, the ducts should minimize flow total pressure loss and total pressure distortion at the duct exit. Changes in the curvature of the duct centerline or the duct cross-sectional shape give rise to streamline curvature which causes cross stream pressure gradients. Secondary flows can be caused by deflection of the transverse vorticity component of the boundary layer. This vortex tilting results in counter-rotating vortices. Additionally, the adverse streamwise pressure gradient caused by increasing cross-sectional area can lead to flow separation. Vortex pairs have been observed in the exit planes of both duct types. These vortices are due to secondary flows induced by pressure gradients resulting from streamline curvature. Regions of low total pressure are produced when the vortices convect boundary layer fluid into the main flow. The purpose of the present study is to predict the measured flow field in a diffusing S-duct and a circular-to-rectangular transition duct with a full Navier-Stokes computer program, PARC3D, and to compare the numerical predictions with new detailed experimental measurements. The work was undertaken to extend previous studies and to provide additional CFD validation data needed to help model flows with strong secondary flow and boundary layer separation. The S-duct computation extends the study of Smith et al, and Harloff et al, which concluded that the computation might be improved by using a finer grid and more advanced turbulence models. The present study compares results for both the Baldwin-Lomas and k-epsilon turbulence models and is conducted with a refined grid. For the transition duct, two inlet conditions were considered, the first with straight flow and the second with swirling flow. The first case permits examination of the effects of the geometric transition on the flow field, while the second case includes the rotational flow effect characteristic of a gas turbine engine.

Individual Spatial Responses towards Roads: Implications for Mortality Risk

PubMed Central

Grilo, Clara; Sousa, Joana; Ascensão, Fernando; Matos, Hugo; Leitão, Inês; Pinheiro, Paula; Costa, Monica; Bernardo, João; Reto, Dyana; Lourenço, Rui; Santos-Reis, Margarida; Revilla, Eloy

2012-01-01

Background Understanding the ecological consequences of roads and developing ways to mitigate their negative effects has become an important goal for many conservation biologists. Most mitigation measures are based on road mortality and barrier effects data. However, studying fine-scale individual spatial responses in roaded landscapes may help develop more cohesive road planning strategies for wildlife conservation. Methodology/Principal Findings We investigated how individuals respond in their spatial behavior toward a highway and its traffic intensity by radio-tracking two common species particularly vulnerable to road mortality (barn owl Tyto alba and stone marten Martes foina). We addressed the following questions: 1) how highways affected home-range location and size in the immediate vicinity of these structures, 2) which road-related features influenced habitat selection, 3) what was the role of different road-related features on movement properties, and 4) which characteristics were associated with crossing events and road-kills. The main findings were: 1) if there was available habitat, barn owls and stone martens may not avoid highways and may even include highways within their home-ranges; 2) both species avoided using areas near the highway when traffic was high, but tended to move toward the highway when streams were in close proximity and where verges offered suitable habitat; and 3) barn owls tended to cross above-grade highway sections while stone martens tended to avoid crossing at leveled highway sections. Conclusions Mortality may be the main road-mediated mechanism that affects barn owl and stone marten populations. Fine-scale movements strongly indicated that a decrease in road mortality risk can be realized by reducing sources of attraction, and by increasing road permeability through measures that promote safe crossings. PMID:22970143

Prediction of hydrodynamics and chemistry of confined turbulent methane-air flames with attention to formation of oxides of nitrogen

NASA Technical Reports Server (NTRS)

Elghobashi, S.; Spalding, D. B.; Srivatsa, S. K.

1977-01-01

A formulation of the governing partial differential equations for fluid flow and reacting chemical species in a tubular combustor is presented. A numerical procedure for the solution of the governing differential equations is described, and models for chemical equilibrium and chemical kinetics calculations are presented. The chemical equilibrium model is used to characterize the hydrocarbon reactions. The chemical kinetics model is used to predict the concentrations of the oxides of nitrogen. The combustor consists of a cylindrical duct of varying cross sections with concentric streams of gaseous fuel and air entering the duct at one end. Four sample cases with specified inlet and boundary conditions are considered, and the results are discussed

Application of local linearization and the transonic equivalence rule to the flow about slender analytic bodies at Mach numbers near 1.0

NASA Technical Reports Server (NTRS)

Tyson, R. W.; Muraca, R. J.

1975-01-01

The local linearization method for axisymmetric flow is combined with the transonic equivalence rule to calculate pressure distribution on slender bodies at free-stream Mach numbers from .8 to 1.2. This is an approximate solution to the transonic flow problem which yields results applicable during the preliminary design stages of a configuration development. The method can be used to determine the aerodynamic loads on parabolic arc bodies having either circular or elliptical cross sections. It is particularly useful in predicting pressure distributions and normal force distributions along the body at small angles of attack. The equations discussed may be extended to include wing-body combinations.

Medicare Payment Penalties and Safety Net Hospital Profitability: Minimal Impact on These Vulnerable Hospitals.

PubMed

Bazzoli, Gloria J; Thompson, Michael P; Waters, Teresa M

2018-02-08

To examine relationships between penalties assessed by Medicare's Hospital Readmission Reduction Program and Value-Based Purchasing Program and hospital financial condition. Centers for Medicare and Medicaid Services, American Hospital Association, and Area Health Resource File data for 4,824 hospital-year observations. Bivariate and multivariate analysis of pooled cross-sectional data. Safety net hospitals have significantly higher HRRP/VBP penalties, but, unlike nonsafety net hospitals, increases in their penalty rate did not significantly affect their total margins. Safety net hospitals appear to rely on nonpatient care revenues to offset higher penalties for the years studied. While reassuring, these funding streams are volatile and may not be able to compensate for cumulative losses over time. © Health Research and Educational Trust.

Applying dam height-storage curve to geomorphic features analysis within virtual geographic environment: a case study of the Hong-Shi-Mao watershed

NASA Astrophysics Data System (ADS)

Wang, Daojun; Gong, Jianhua; Ma, Ainai; Li, Wenhang; Wang, Xijun

2005-10-01

There are generally two kinds of approaches to studying geomorphic features in terms of the quantification level and difference of major considerations. One is the earlier qualitative characterization, and the other is the 2-dimension measurement that includes section pattern and projection pattern. With the development of geo-information technology, especially the 3-D geo-visualization and virtual geographic environments (VGE), 3-dimension measurement and dynamic interactive between users and geo-data/geo-graphics can be developed to understand geomorphic features deeply, and to benefit to the effective applications of such features for geographic projects like dam construction. Storage-elevation curve is very useful for site selection of projects and flood dispatching in water conservancy region, but it is just a tool querying one value from the other one. In fact, storage-elevation curve can represent comprehensively the geomorphic features including vertical section, cross section of the stream and the landform nearby. In this paper, we use quadratic regression equation shaped like y = ax2 + bx + c and the DEM data of Hong-Shi-Mao watershed, Zi Chang County, ShaanXi Province, China to find out the relationship between the coefficients of the equation and the geomorphic features based on VGE platform. It's exciting that the coefficient "a" appear to be correlative strongly with the stream scale, and the coefficient "b" may give an index to the valley shape. In the end, we use a sub-basin named Hao-Jia-Gou of the watershed as an application. The result of correlative research about quadratic regression equation and geomorphic features can save computing and improve the efficiency in silt dam systems planning.

An investigation into the mechanisms of drag reduction of a boat tailed base cavity on a blunt based body

NASA Astrophysics Data System (ADS)

Kehs, Joshua Paul

It is well documented in the literature that boat-tailed base cavities reduce the drag on blunt based bodies. The majority of the previous work has been focused on the final result, namely reporting the resulting drag reduction or base pressure increase without examining the methods in which such a device changes the fluid flow to enact such end results. The current work investigates the underlying physical means in which these devices change the flow around the body so as to reduce the overall drag. A canonical model with square cross section was developed for the purpose of studying the flow field around a blunt based body. The boat-tailed base cavity tested consisted of 4 panels of length equal to half the width of the body extending from the edges of the base at an angle towards the models center axis of 12°. Drag and surface pressure measurements were made at Reynolds numbers based on width from 2.3x105 to 3.6x10 5 in the Clarkson University high-speed wind tunnel over a range of pitch and yaw angles. Cross-stream hotwire wake surveys were used to identify wake width and turbulence intensities aft of the body at Reynolds numbers of 2.3x105 to 3.0x105. Particle Image Velocimetry (PIV) was used to quantify the flow field in the wake of the body, including the mean flow, vorticity, and turbulence measurements. The results indicated that the boat-tailed aft cavity decreases the drag significantly due to increased pressure on the base. Hotwire measurements indicated a reduction in wake width as well as a reduction in turbulence in the wake. PIV measurements indicated a significant reduction in wake turbulence and revealed that there exists a co-flowing stream that exits the cavity parallel to the free stream, reducing the shear in the flow at the flow separation point. The reduction in shear at the separation point indicated the method by which the turbulence was reduced. The reduction in turbulence combined with the reduction in wake size provided the mechanism of drag reduction by limiting the rate of entrainment of fluid in the recirculating wake to the free stream and by limiting the area over which this entrainment occurs.

Analyzing Conductivity Profiles in Stream Waters Influenced by Mine Water Discharges

NASA Astrophysics Data System (ADS)

Räsänen, Teemu; Hämäläinen, Emmy; Hämäläinen, Matias; Turunen, Kaisa; Pajula, Pasi; Backnäs, Soile

2015-04-01

Conductivity is useful as a general measure of stream water quality. Each stream inclines to have a quite constant range of conductivity that can be used as a baseline for comparing and detecting influence of contaminant sources. Conductivity in natural streams and rivers is affected primarily by the geology of the watershed. Thus discharges from ditches and streams affect not only the flow rate in the river but also the water quality and conductivity. In natural stream waters, the depth and the shape of the river channel change constantly, which changes also the water flow. Thus, an accurate measuring of conductivity or other water quality indicators is difficult. Reliable measurements are needed in order to have holistic view about amount of contaminants, sources of discharges and seasonal variation in mixing and dilution processes controlling the conductivity changes in river system. We tested the utility of CastAway-CTD measuring device (SonTek Inc) to indicate the influence of mine waters as well as mixing and dilution occurring in the recipient river affected by treated dewatering and process effluent water discharges from a Finnish gold mine. The CastAway-CTD measuring device is a small, rugged and designed for profiling of depths of up to 100m. Device measures temperature, salinity, conductivity and sound of speed using 5 Hz response time. It has also built-in GPS which produces location information. CTD casts are normally used to produce vertical conductivity profile for rather deep waters like seas or lakes. We did seasonal multiple Castaway-CTD measurements during 2013 and 2014 and produced scaled vertical and horizontal profiles of conductivity and water temperature at the river. CastAway-CTD measurement pinpoints how possible contaminants behave and locate in stream waters. The conductivity profiles measured by CastAway-CTD device show the variation in maximum conductivity values vertically in measuring locations and horizontally in measured cross-sections. The data from field measurements was combined with detailed water quality analysis and processed by data analysis with Matlab to produce more holistic information about the behavior, mixing and dilution of possible contaminants at the river. Moreover, the results can be used to improve water sampling procedures for more representative sampling and to plan continuous monitoring site locations and measuring device mounting places.

River banks and channel axis curvature: Effects on the longitudinal dispersion in alluvial rivers

NASA Astrophysics Data System (ADS)

Lanzoni, Stefano; Ferdousi, Amena; Tambroni, Nicoletta

2018-03-01

The fate and transport of soluble contaminants released in natural streams are strongly dependent on the spatial variations of the flow field and of the bed topography. These variations are essentially related to the presence of the channel banks and to the planform configuration of the channel. Large velocity gradients arise near to the channel banks, where the flow depth decreases to zero. Moreover, single thread alluvial rivers are seldom straight, and usually exhibit meandering planforms and a bed topography that deviates from the plane configuration. Channel axis curvature and movable bed deformations drive secondary helical currents which enhance both cross sectional velocity gradients and transverse mixing, thus crucially influencing longitudinal dispersion. The present contribution sets up a rational framework which, assuming mild sloping banks and taking advantage of the weakly meandering character often exhibited by natural streams, leads to an analytical estimate of the contribution to longitudinal dispersion associated with spatial non-uniformities of the flow field. The resulting relationship stems from a physics-based modeling of the flow in natural rivers, and expresses the bend averaged longitudinal dispersion coefficient as a function of the relevant hydraulic and morphologic parameters. The treatment of the problem is river specific, since it relies on an explicit spatial description, although linearized, of the flow field that establishes in the investigated river. Comparison with field data available from tracer tests supports the robustness of the proposed framework, given also the complexity of the processes that affect dispersion dynamics in real streams.

A neighborhood statistics model for predicting stream pathogen indicator levels.

PubMed

Pandey, Pramod K; Pasternack, Gregory B; Majumder, Mahbubul; Soupir, Michelle L; Kaiser, Mark S

2015-03-01

Because elevated levels of water-borne Escherichia coli in streams are a leading cause of water quality impairments in the U.S., water-quality managers need tools for predicting aqueous E. coli levels. Presently, E. coli levels may be predicted using complex mechanistic models that have a high degree of unchecked uncertainty or simpler statistical models. To assess spatio-temporal patterns of instream E. coli levels, herein we measured E. coli, a pathogen indicator, at 16 sites (at four different times) within the Squaw Creek watershed, Iowa, and subsequently, the Markov Random Field model was exploited to develop a neighborhood statistics model for predicting instream E. coli levels. Two observed covariates, local water temperature (degrees Celsius) and mean cross-sectional depth (meters), were used as inputs to the model. Predictions of E. coli levels in the water column were compared with independent observational data collected from 16 in-stream locations. The results revealed that spatio-temporal averages of predicted and observed E. coli levels were extremely close. Approximately 66 % of individual predicted E. coli concentrations were within a factor of 2 of the observed values. In only one event, the difference between prediction and observation was beyond one order of magnitude. The mean of all predicted values at 16 locations was approximately 1 % higher than the mean of the observed values. The approach presented here will be useful while assessing instream contaminations such as pathogen/pathogen indicator levels at the watershed scale.

Channel representation in physically based models coupling groundwater and surface water: pitfalls and how to avoid them.

PubMed

Käser, Daniel; Graf, Tobias; Cochand, Fabien; McLaren, Rob; Therrien, René; Brunner, Philip

2014-01-01

Recent models that couple three-dimensional subsurface flow with two-dimensional overland flow are valuable tools for quantifying complex groundwater/stream interactions and for evaluating their influence on watershed processes. For the modeler who is used to defining streams as a boundary condition, the representation of channels in integrated models raises a number of conceptual and technical issues. These models are far more sensitive to channel topography than conventional groundwater models. On all spatial scales, both the topography of a channel and its connection with the floodplain are important. For example, the geometry of river banks influences bank storage and overbank flooding; the slope of the river is a primary control on the behavior of a catchment; and at the finer scale bedform characteristics affect hyporheic exchange. Accurate data on streambed topography, however, are seldom available, and the spatial resolution of digital elevation models is typically too coarse in river environments, resulting in unrealistic or undulating streambeds. Modelers therefore perform some kind of manual yet often cumbersome correction to the available topography. In this context, the paper identifies some common pitfalls, and provides guidance to overcome these. Both aspects of topographic representation and mesh discretization are addressed. Additionally, two tutorials are provided to illustrate: (1) the interpolation of channel cross-sectional data and (2) the refinement of a mesh along a stream in areas of high topographic variability. © 2014, National Ground Water Association.

Age and experience shape developmental changes in the neural basis of language-related learning.

PubMed

McNealy, Kristin; Mazziotta, John C; Dapretto, Mirella

2011-11-01

Very little is known about the neural underpinnings of language learning across the lifespan and how these might be modified by maturational and experiential factors. Building on behavioral research highlighting the importance of early word segmentation (i.e. the detection of word boundaries in continuous speech) for subsequent language learning, here we characterize developmental changes in brain activity as this process occurs online, using data collected in a mixed cross-sectional and longitudinal design. One hundred and fifty-six participants, ranging from age 5 to adulthood, underwent functional magnetic resonance imaging (fMRI) while listening to three novel streams of continuous speech, which contained either strong statistical regularities, strong statistical regularities and speech cues, or weak statistical regularities providing minimal cues to word boundaries. All age groups displayed significant signal increases over time in temporal cortices for the streams with high statistical regularities; however, we observed a significant right-to-left shift in the laterality of these learning-related increases with age. Interestingly, only the 5- to 10-year-old children displayed significant signal increases for the stream with low statistical regularities, suggesting an age-related decrease in sensitivity to more subtle statistical cues. Further, in a sample of 78 10-year-olds, we examined the impact of proficiency in a second language and level of pubertal development on learning-related signal increases, showing that the brain regions involved in language learning are influenced by both experiential and maturational factors. 2011 Blackwell Publishing Ltd.

Geomorphic responses of Duluth-area streams to the June 2012 flood, Minnesota

USGS Publications Warehouse

Fitzpatrick, Faith A.; Ellison, Christopher A.; Czuba, Christiana R.; Young, Benjamin M.; McCool, Molly M.; Groten, Joel T.

2016-09-01

In 2013, the U.S. Geological Survey, in cooperation with the Minnesota Pollution Control Agency, completed a geomorphic assessment of 51 Duluth-area stream sites in 20 basins to describe and document the stream geomorphic changes associated with the June 2012 flood. Heavy rainfall caused flood peaks with annual exceedance probabilities of less than 0.002 (flood recurrence interval of greater than 500 years) on large and small streams in and surrounding the Duluth area. A geomorphic segment-scale classification previously developed in 2003–4 by the U.S. Geological Survey for Duluth-area streams was used as a framework to characterize the observed flood-related responses along a longitudinal continuum from headwaters to rivermouths at Lake Superior related to drainage network position, slope, geologic setting, and valley type. Field assessments in 2013 followed and expanded on techniques used in 2003–4 at intensive and rapid sites. A third level of assessment was added in 2013 to increase the amount of quantitative data at a subset of 2003–4 rapid sites. Characteristics of channel morphology, channel bed substrate, exposed bars and soft sediment deposition, large wood, pools, and bank erosion were measured; and repeat photographs were taken. Additional measurements in 2013 included identification of Rosgen Level II stream types. The comparative analyses of field data collected in 2003–4 and again in 2013 indicated notable geomorphic changes, some of them expected and others not. As expected, in headwaters with gently sloping wetland segments, geomorphic changes were negligible (little measured or observed change). Downstream, middle main stems generally had bank and bluff erosion and bar formation as expected. Steep bedrock sites along middle and lower main stems had localized bank and bluff erosion in short sections with intermittent bedrock. Lower main stem and alluvial sites had bank erosion, widening, gravel bar deposition, and aggradation. Bar formation and accumulation of gravel was more widespread than expected among all main stems, especially for sites upstream and downstream from channel constrictions from road crossings, or even steep sites with localized, more gently sloping sections. Decreases in large wood and pools also were observed throughout the longitudinal continuum of main-stem sites, with immediate implications for fish and benthic invertebrate aquatic habitat. Whether or not the geomorphic conditions will return to their preflood condition depends on the location along the longitudinal continuum. The amount of large wood and pools may return after more moderate floods, whereas bars with coarse material may remain in place, locally altering flow direction and causing continued bank erosion. Results from this study can be used by local managers in postflood reconstruction efforts and provide baseline information for continued monitoring of geomorphic responses to the June 2012 flood.

Trophic state, eutrophication and nutrient criteria in streams.

PubMed

Dodds, Walter K

2007-12-01

Trophic state is the property of energy availability to the food web and defines the foundation of community integrity and ecosystem function. Describing trophic state in streams requires a stoichiometric (nutrient ratio) approach because carbon input rates are linked to nitrogen and phosphorus supply rates. Light determines the source of carbon. Cross system analyses, small experiments and ecosystem level manipulations have recently advanced knowledge about these linkages, but not to the point of building complex predictive models that predict all effects of nutrient pollution. Species diversity could indicate the natural distribution of stream trophic status over evolutionary time scales. Delineation of factors that control trophic state and relationships with biological community properties allows determination of goals for management of stream biotic integrity.

Design guidance for low-water crossings in areas of extreme bed mobility, Edwards Plateau, Texas.

DOT National Transportation Integrated Search

2009-03-23

The purpose of this report is to present results from a combination of field and laboratory investigations of mobility : of gravel to cobble sized materials in Texas streams on the Edwards Plateau. TxDOT uses low-water crossings for : many of the roa...

Application of Hierarchy Theory to Cross-Scale Hydrologic Modeling of Nutrient Loads

EPA Science Inventory

We describe a model called Regional Hydrologic Modeling for Environmental Evaluation 16 (RHyME²) for quantifying annual nutrient loads in stream networks and watersheds. RHyME² is 17 a cross-scale statistical and process-based water-quality model. The model ...

Frequency-following and connectivity of different visual areas in response to contrast-reversal stimulation.

PubMed

Stephen, Julia M; Ranken, Doug F; Aine, Cheryl J

2006-01-01

The sensitivity of visual areas to different temporal frequencies, as well as the functional connections between these areas, was examined using magnetoencephalography (MEG). Alternating circular sinusoids (0, 3.1, 8.7 and 14 Hz) were presented to foveal and peripheral locations in the visual field to target ventral and dorsal stream structures, respectively. It was hypothesized that higher temporal frequencies would preferentially activate dorsal stream structures. To determine the effect of frequency on the cortical response we analyzed the late time interval (220-770 ms) using a multi-dipole spatio-temporal analysis approach to provide source locations and timecourses for each condition. As an exploratory aspect, we performed cross-correlation analysis on the source timecourses to determine which sources responded similarly within conditions. Contrary to predictions, dorsal stream areas were not activated more frequently during high temporal frequency stimulation. However, across cortical sources the frequency-following response showed a difference, with significantly higher power at the second harmonic for the 3.1 and 8.7 Hz stimulation and at the first and second harmonics for the 14 Hz stimulation with this pattern seen robustly in area V1. Cross-correlations of the source timecourses showed that both low- and high-order visual areas, including dorsal and ventral stream areas, were significantly correlated in the late time interval. The results imply that frequency information is transferred to higher-order visual areas without translation. Despite the less complex waveforms seen in the late interval of time, the cross-correlation results show that visual, temporal and parietal cortical areas are intricately involved in late-interval visual processing.

Estimating flood hydrographs and volumes for Alabama streams

USGS Publications Warehouse

Olin, D.A.; Atkins, J.B.

1988-01-01

The hydraulic design of highway drainage structures involves an evaluation of the effect of the proposed highway structures on lives, property, and stream stability. Flood hydrographs and associated flood volumes are useful tools in evaluating these effects. For design purposes, the Alabama Highway Department needs information on flood hydrographs and volumes associated with flood peaks of specific recurrence intervals (design floods) at proposed or existing bridge crossings. This report will provide the engineer with a method to estimate flood hydrographs, volumes, and lagtimes for rural and urban streams in Alabama with drainage areas less than 500 sq mi. Existing computer programs and methods to estimate flood hydrographs and volumes for ungaged streams have been developed in Georgia. These computer programs and methods were applied to streams in Alabama. The report gives detailed instructions on how to estimate flood hydrographs for ungaged rural or urban streams in Alabama with drainage areas less than 500 sq mi, without significant in-channel storage or regulations. (USGS)

Fish Assemblages in Streams Subject to Anthropogenic Disturbances Along The Natchez Trace Parkway, Mississippi, USA

PubMed Central

Hashim, Rohasliney; Jackson, Donald C

2009-01-01

A three-year study (July 2000 – June 2003) of fish assemblages was conducted in four tributaries of the Big Black River: Big Bywy, Little Bywy, Middle Bywy and McCurtain creeks that cross the Natchez Trace Parkway, Choctaw County, Mississippi, USA. Little Bywy and Middle Bywy creeks were within watersheds influenced by the lignite mining. Big Bywy and Middle Bywy creeks were historically impacted by channelisation. McCurtain Creek was chosen as a reference (control) stream. Fish were collected using a portable backpack electrofishing unit (Smith-Root Inc., Washington, USA). Insectivorous fish dominated all of the streams. There were no pronounced differences in relative abundances of fishes among the streams (P > 0.05) but fish assemblages fluctuated seasonally. Although there were some differences among streams with regard to individual species, channelisation and lignite mining had no discernable adverse effects on functional components of fish assemblages suggesting that fishes in these systems are euryceous fluvial generalist species adapted to the variable environments of small stream ecosystems. PMID:24575177

Modeling streamflow from coupled airborne laser scanning and acoustic Doppler current profiler data

USGS Publications Warehouse

Norris, Lam; Kean, Jason W.; Lyon, Steve

2016-01-01

The rating curve enables the translation of water depth into stream discharge through a reference cross-section. This study investigates coupling national scale airborne laser scanning (ALS) and acoustic Doppler current profiler (ADCP) bathymetric survey data for generating stream rating curves. A digital terrain model was defined from these data and applied in a physically based 1-D hydraulic model to generate rating curves for a regularly monitored location in northern Sweden. Analysis of the ALS data showed that overestimation of the streambank elevation could be adjusted with a root mean square error (RMSE) block adjustment using a higher accuracy manual topographic survey. The results of our study demonstrate that the rating curve generated from the vertically corrected ALS data combined with ADCP data had lower errors (RMSE = 0.79 m3/s) than the empirical rating curve (RMSE = 1.13 m3/s) when compared to streamflow measurements. We consider these findings encouraging as hydrometric agencies can potentially leverage national-scale ALS and ADCP instrumentation to reduce the cost and effort required for maintaining and establishing rating curves at gauging station sites similar to the Röån River.

Refinement of Fread s Method for improved tracking of stream discharges during unsteady flows

DOE PAGES

Lee, Kyutae; Muste, Marian

2017-02-07

There are a plethora of analytical approaches to account for the effect of unsteady flow (a.k.a. hysteretic behavior) on the conventionally-built steady rating curves (RCs) used to continuously estimate discharges in open channel flow. One of the most complete correction methods is Fread s method (Fread, 1975) which is based on fully dynamic one-dimensional wave equation. Proposed herein is a modified Fread s method which is adjusted to account for the actual geometry of the cross section. This method improves the accuracy associated with the estimation of conveyance factor and energy slope, so it is particularly useful for small tomore » mid-size streams/rivers where the original method s assumption does not properly hold. The modified Fread s method is tested for the sites in Clear Creek (Iowa, USA) and Ebro River (Spain) to illustrate the significance of its improvement in discharge estimation. While the degree of improvement is apparent for the conveyance factor because the hydraulic depth is replaced by hydraulic radius, that for the energy slope term specifically depends on the site and event conditions.« less

Channel geometry change of a first-order stream after a small debris flow in Ashio Mountains of central Japan

NASA Astrophysics Data System (ADS)

Hattanji, T.; Wasklewicz, T.

2006-12-01

We examined geometry change of a steep first-order channel with a laserscanner before and after a small debris flow. The study site is located in chert area, Ashio Mountains, Japan. On August 12, 2005, a 20-year storm event with maximum 1-hour rainfall of 75.4 mm/h triggered a small landslide at a steep channel head. The sliding material moved as a debris flow along the first-order channel (C3) to the mouth. We successfully measured high-resolution channel topography with the Leica Geosystems High-Definition Surveying Laser Scanner before (April 30) and after the debris-flow event (October 9-11). Width, depth and other related parameters were measured for 30 selected cross sections. Bankfull stage of this first-order channel after the debris-flow event is much higher than two-year flood stage. The magnitude of channel geometry change varies non-linearly in downstream direction. The non-linear variability is attributed to differences in stream bed and bank characteristics. Bedrock-channel reach is less impacted by the debris flow. The largest magnitude changes in the channel geometry parameters occur along colluvially confined channel reaches.

Refinement of Fread s Method for improved tracking of stream discharges during unsteady flows

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Kyutae; Muste, Marian

There are a plethora of analytical approaches to account for the effect of unsteady flow (a.k.a. hysteretic behavior) on the conventionally-built steady rating curves (RCs) used to continuously estimate discharges in open channel flow. One of the most complete correction methods is Fread s method (Fread, 1975) which is based on fully dynamic one-dimensional wave equation. Proposed herein is a modified Fread s method which is adjusted to account for the actual geometry of the cross section. This method improves the accuracy associated with the estimation of conveyance factor and energy slope, so it is particularly useful for small tomore » mid-size streams/rivers where the original method s assumption does not properly hold. The modified Fread s method is tested for the sites in Clear Creek (Iowa, USA) and Ebro River (Spain) to illustrate the significance of its improvement in discharge estimation. While the degree of improvement is apparent for the conveyance factor because the hydraulic depth is replaced by hydraulic radius, that for the energy slope term specifically depends on the site and event conditions.« less

Trans-Pacific tele-ultrasound image transmission of fetal central nervous system structures.

PubMed

Ferreira, Adilson Cunha; Araujo Júnior, Edward; Martins, Wellington P; Jordão, João Francisco; Oliani, Antônio Hélio; Meagher, Simon E; Da Silva Costa, Fabricio

2015-01-01

To assess the quality of images and video clips of fetal central nervous (CNS) structures obtained by ultrasound and transmitted via tele-ultrasound from Brazil to Australia. In this cross-sectional study, 15 normal singleton pregnant women between 20 and 26 weeks were selected. Fetal CNS structures were obtained by images and video clips. The exams were transmitted in real-time using a broadband internet and an inexpensive video streaming device. Four blinded examiners evaluated the quality of the exams using the Likert scale. We calculated the mean, standard deviation, mean difference, and p values were obtained from paired t tests. The quality of the original video clips was slightly better than that observed by the transmitted video clips; mean difference considering all observers = 0.23 points. In 47/60 comparisons (78.3%; 95% CI = 66.4-86.9%) the quality of the video clips were judged to be the same. In 182/240 still images (75.8%; 95% CI = 70.0-80.8%) the scores of transmitted image were considered the same as the original. We demonstrated that long distance tele-ultrasound transmission of fetal CNS structures using an inexpensive video streaming device provided images of subjective good quality.

Mental health of Chinese primary care patients with lower urinary tract symptoms.

PubMed

Choi, Edmond P H; Lam, Cindy L K; Chin, Weng Yee

2016-01-01

The aim of this study was to evaluate the mental health of Chinese primary care patients with lower urinary tract symptoms (LUTS). This was a cross-sectional observational study. Five hundred and nineteen subjects with LUTS completed a structured questionnaire containing the Depression, Anxiety, and Stress Scale-Short Form, the International Prostate Symptom Score, the adapted International Consultation on Incontinence Questionnaire-Urinary Incontinence Short Form and questions about socio-demographics. Overall, 17.7% of subjects reported depressive symptoms, 24.3% anxiety symptoms and 9.6% stress symptoms. In males, demographic factors associated with poorer mental health included being not married; clinical factors included higher LUTS severity, weak stream, straining and mixed urinary incontinence. In females, demographic factors associated with poorer mental health included being younger, not married and lower household income; clinical factors included higher LUTS severity, incomplete bladder emptying, urgency and weak stream. Chinese primary care patients with LUTS appear to be an at-risk group for poorer mental health with increased prevalence of anxiety and depressive symptoms and may require routine screening to identify those who may require more tailored interventions to address both their urinary symptoms and psychological distress.

Direct simulation of high-speed mixing layers

NASA Technical Reports Server (NTRS)

Mukunda, H. S.; Sekar, B.; Carpenter, M. H.; Drummond, J. Philip; Kumar, Ajay

1992-01-01

A computational study of a nonreacting high-speed mixing layer is performed. A higher order algorithm with sufficient grid points is used to resolve all relevant scales. In all cases, a temporal free-stream disturbance is introduced. The resulting flow is time-sampled to generate a statistical cross section of the flow properties. The studies are conducted at two convective Mach numbers, three free-stream turbulence intensities, three Reynolds numbers, and two types of initial profiles-hyperbolic tangent (tanh) and boundary layer. The boundary-layer profile leads to more realistic predictions of the transition processes. The predicted transition Reynolds number of 0.18 x 10(exp 6) compares well with experimental data. Normalized vortex spacings for the boundary-layer case are about 3.5 and compare favorably with the 1.5 to 2.5 found in experimental measurements. The tanh profile produces spacings of about 10. The growth rate of the layer is shown to be moderately affected by the initial disturbance field, but comparison with experimental data shows moderate agreement. For the boundary-layer case, it is shown that noise at the Strouhal number of 0.007 is selectively amplified and shows little Reynolds number dependence.

40 CFR 65.83 - Performance requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... stream nonhalogenated by reducing the vent stream halogen atom mass emission rate to less than 0.45... requirements of paragraph (a)(1) or (2) of this section. The mass emission rate of halogen atoms contained in...

40 CFR 65.83 - Performance requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... stream nonhalogenated by reducing the vent stream halogen atom mass emission rate to less than 0.45... requirements of paragraph (a)(1) or (2) of this section. The mass emission rate of halogen atoms contained in...

40 CFR 65.83 - Performance requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

... stream nonhalogenated by reducing the vent stream halogen atom mass emission rate to less than 0.45... requirements of paragraph (a)(1) or (2) of this section. The mass emission rate of halogen atoms contained in...

40 CFR 65.83 - Performance requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... stream nonhalogenated by reducing the vent stream halogen atom mass emission rate to less than 0.45... requirements of paragraph (a)(1) or (2) of this section. The mass emission rate of halogen atoms contained in...

40 CFR 65.83 - Performance requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

... stream nonhalogenated by reducing the vent stream halogen atom mass emission rate to less than 0.45... requirements of paragraph (a)(1) or (2) of this section. The mass emission rate of halogen atoms contained in...

Habitat-dependent interactions between two size-classes of juvenile steelhead in a small stream

Treesearch

Bret C. Harvey; Rodney J. Nakamoto

1997-01-01

Abstract - The presence of small steelhead (Oncorhynchus mykiss; averaging 55 mm fork length) influenced the growth of larger juvenile steelhead (90 mm fork length) during a 6-week experiment conducted in North Fork Caspar Creek, California, in summer 1994. In fenced replicate deep stream sections in this small stream, growth of the larger steelhead was greater in...

Water temperature, dissolved oxygen, flow, and shade measurements in the three stream sections of the Golden Trout Wilderness

Treesearch

Kathleen R. Matthews

2016-01-01

To determine the current range of water temperatures in the streams inhabited by California golden trout, Oncorhynchus mykiss aguabonita, I deployed and monitored water temperature recording probes from 2008 through 2013 in three meadows in the Golden Trout Wilderness (GTW). Ninety probes were placed in three meadow streams: Mulkey Creek in Mulkey...

76 FR 65225 - Self-Regulatory Organizations; NASDAQ OMX PHLX LLC; Notice of Filing and Immediate Effectiveness...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-20

... proposes to amend the Remote Streaming Quote Trader (``RSQT'') \\3\\ Fee in Section VI of the Exchange's Fee... Options Trader (``ROT'') includes a Streaming Quote Trader (``SQT''), a Remote Streaming Quote Trader... extent that the RSQT is also approved as a Remote Specialist in the same options.\\6\\ \\4\\ A qualified RSQT...

Low capital implementation of distributed distillation in ethylene recovery

DOEpatents

Reyneke, Rian; Foral, Michael J.; Lee, Guang-Chung

2006-10-31

An apparatus for recovering ethylene from a hydrocarbon feed stream, where the apparatus is a single distillation column pressure shell encasing an upper region and a lower region. The upper region houses an ethylene distributor rectifying section and the lower region houses a C2 distributor section and an ethylene distributor stripping section. Vapor passes from the lower region into the upper region, and liquid passes from the upper region to the lower region. The process for recovering the ethylene is also disclosed. The hydrocarbon feed stream is introduced into the C2 distributor section, and after a series of stripping and refluxing steps, distinct hydrocarbon products are recovered from the C2 distributor section, the ethylene distributor stripping section, and the ethylene distributor rectifying section, respectively.

Electrokinetic mixing at high zeta potentials: ionic size effects on cross stream diffusion.

PubMed

Ahmadian Yazdi, Alireza; Sadeghi, Arman; Saidi, Mohammad Hassan

2015-03-15

The electrokinetic phenomena at high zeta potentials may show several unique features which are not normally observed. One of these features is the ionic size (steric) effect associated with the solutions of high ionic concentration. In the present work, attention is given to the influences of finite ionic size on the cross stream diffusion process in an electrokinetically actuated Y-shaped micromixer. The method consists of a finite difference based numerical approach for non-uniform grid which is applied to the dimensionless form of the governing equations, including the modified Poisson-Boltzmann equation. The results reveal that, neglecting the ionic size at high zeta potentials gives rise to the overestimation of the mixing length, because the steric effects retard liquid flow, thereby enhancing the mixing efficiency. The importance of steric effects is found to be more intense for channels of smaller width to height ratio. It is also observed that, in sharp contrast to the conditions that the ions are treated as point charges, increasing the zeta potential improves the cross stream diffusion when incorporating the ionic size. Moreover, increasing the EDL thickness decreases the mixing length, whereas the opposite is true for the channel aspect ratio. Copyright © 2014 Elsevier Inc. All rights reserved.

The structure of a three-dimensional turbulent boundary layer

NASA Technical Reports Server (NTRS)

Degani, A. T.; Smith, F. T.; Walker, J. D. A.

1993-01-01

The three-dimensional turbulent boundary layer is shown to have a self-consistent two-layer asymptotic structure in the limit of large Reynolds number. In a streamline coordinate system, the streamwise velocity distribution is similar to that in two-dimensional flows, having a defect-function form in the outer layer which is adjusted to zero at the wall through an inner wall layer. An asymptotic expansion accurate to two orders is required for the cross-stream velocity which is shown to exhibit a logarithmic form in the overlap region. The inner wall-layer flow is collateral to leading order but the influence of the pressure gradient, at large but finite Reynolds numbers, is not negligible and can cause substantial skewing of the velocity profile near the wall. Conditions under which the boundary layer achieves self-similarity and the governing set of ordinary differential equations for the outer layer are derived. The calculated solution of these equations is matched asymptotically to an inner wall-layer solution and the composite profiles so formed describe the flow throughout the entire boundary layer. The effects of Reynolds number and cross-stream pressure gradient on the crossstream velocity profile are discussed and it is shown that the location of the maximum cross-stream velocity is within the overlap region.

Application of a multistate model to estimate culvert effects on movement of small fishes

USGS Publications Warehouse

Norman, J.R.; Hagler, M.M.; Freeman, Mary C.; Freeman, B.J.

2009-01-01

While it is widely acknowledged that culverted road-stream crossings may impede fish passage, effects of culverts on movement of nongame and small-bodied fishes have not been extensively studied and studies generally have not accounted for spatial variation in capture probabilities. We estimated probabilities for upstream and downstream movement of small (30-120 mm standard length) benthic and water column fishes across stream reaches with and without culverts at four road-stream crossings over a 4-6-week period. Movement and reach-specific capture probabilities were estimated using multistate capture-recapture models. Although none of the culverts were complete barriers to passage, only a bottomless-box culvert appeared to permit unrestricted upstream and downstream movements by benthic fishes based on model estimates of movement probabilities. At two box culverts that were perched above the water surface at base flow, observed movements were limited to water column fishes and to intervals when runoff from storm events raised water levels above the perched level. Only a single fish was observed to move through a partially embedded pipe culvert. Estimates for probabilities of movement over distances equal to at least the length of one culvert were low (e.g., generally ???0.03, estimated for 1-2-week intervals) and had wide 95% confidence intervals as a consequence of few observed movements to nonadjacent reaches. Estimates of capture probabilities varied among reaches by a factor of 2 to over 10, illustrating the importance of accounting for spatially variable capture rates when estimating movement probabilities with capture-recapture data. Longer-term studies are needed to evaluate temporal variability in stream fish passage at culverts (e.g., in relation to streamflow variability) and to thereby better quantify the degree of population fragmentation caused by road-stream crossings with culverts. ?? American Fisheries Society 2009.

Neural practice effect during cross-modal selective attention: Supra-modal and modality-specific effects.

PubMed

Xia, Jing; Zhang, Wei; Jiang, Yizhou; Li, You; Chen, Qi

2018-05-16

Practice and experiences gradually shape the central nervous system, from the synaptic level to large-scale neural networks. In natural multisensory environment, even when inundated by streams of information from multiple sensory modalities, our brain does not give equal weight to different modalities. Rather, visual information more frequently receives preferential processing and eventually dominates consciousness and behavior, i.e., visual dominance. It remains unknown, however, the supra-modal and modality-specific practice effect during cross-modal selective attention, and moreover whether the practice effect shows similar modality preferences as the visual dominance effect in the multisensory environment. To answer the above two questions, we adopted a cross-modal selective attention paradigm in conjunction with the hybrid fMRI design. Behaviorally, visual performance significantly improved while auditory performance remained constant with practice, indicating that visual attention more flexibly adapted behavior with practice than auditory attention. At the neural level, the practice effect was associated with decreasing neural activity in the frontoparietal executive network and increasing activity in the default mode network, which occurred independently of the modality attended, i.e., the supra-modal mechanisms. On the other hand, functional decoupling between the auditory and the visual system was observed with the progress of practice, which varied as a function of the modality attended. The auditory system was functionally decoupled with both the dorsal and ventral visual stream during auditory attention while was decoupled only with the ventral visual stream during visual attention. To efficiently suppress the irrelevant visual information with practice, auditory attention needs to additionally decouple the auditory system from the dorsal visual stream. The modality-specific mechanisms, together with the behavioral effect, thus support the visual dominance model in terms of the practice effect during cross-modal selective attention. Copyright © 2018 Elsevier Ltd. All rights reserved.

Measuring stream discharge by non-contact methods: A proof-of-concept experiment

USGS Publications Warehouse

Costa, J.E.; Spicer, K.R.; Cheng, R.T.; Haeni, F.P.; Melcher, N.B.; Thurman, E.M.; Plant, W.J.; Keller, W.C.

2000-01-01

This report describes an experiment to make a completely non-contact open-channel discharge measurement. A van-mounted, pulsed doppler (10GHz) radar collected surface-velocity data across the 183-m wide Skagit River, Washington at a USGS streamgaging station using Bragg scattering from short waves produced by turbulent boils on the surface of the river. Surface velocities were converted to mean velocities for 25 sub-sections by assuming a normal open-channel velocity profile (surface velocity times 0.85). Channel cross-sectional area was measured using a 100 MHz ground-penetrating radar antenna suspended from a cableway car over the river. Seven acoustic doppler current profiler discharge measurements and a conventional current-meter discharge measurement were also made. Three non-contact discharge measurements completed in about a 1-hour period were within 1 % of the gaging station rating curve discharge values. With further refinements, it is thought that open-channel flow can be measured reliably by non-contact methods.

The Jet Stream's Precursor of M7.7 Russia Earthquake on 2017/07/17

NASA Astrophysics Data System (ADS)

Wu, H. C.

2017-12-01

Before M>6.0 earthquakes occurred, jet stream in the epicenter area will interrupt or velocity flow lines cross. That meaning is that before earthquake happen, atmospheric pressure in high altitude suddenly dropped during 6 12 hours (Wu & Tikhonov, 2014; Wu et.al,2015). The 70 knots speed line in jet stream was crossed at the epicenter on 2017/07/13, and then M7.7 Russia earthquake happened on 2017/07/17. Lithosphere-atmosphere-ionosphere (LAI) coupling model may be explained this phenomenon : Ionization of the air produced by an increased emanation of radon at epicenter. The water molecules in the air react with these ions, and then release heat. The heat result in temperature rise and pressure drop in the air(Pulinets, Ouzounov, 2011), and then the speed line of jet stream was changed. ps.Russia earthquake:M7.7 2017-07-17 23:34:13 (UTC) 54.471°N 168.815°E 11.0 kmReference: H.C Wu, I.N. Tikhonov, 2014, "Jet streams anomalies as possible short-term precursors of earthquakes with M>6.0", Research in geophysics. H.C.Wu., Ivan N. Tikhonov, and Ariel R. Ćesped,2015, Multi-parametric analysis of earthquake precursors, Russ. J. Earth. Sci., 15, ES3002, doi:10.2205/2015ES000553 S Pulinets, D Ouzounov, 2011,"Lithosphere-Atmosphere-Ionosphere Coupling (LAIC) model-An unified concept for earthquake precursors validation", Journal of Asian Earth Sciences 41 (4), 371-382.

Pseudo-spectral methodology for a quantitative assessment of the cover of in-stream vegetation in small streams

NASA Astrophysics Data System (ADS)

Hershkovitz, Yaron; Anker, Yaakov; Ben-Dor, Eyal; Schwartz, Guy; Gasith, Avital

2010-05-01

In-stream vegetation is a key ecosystem component in many fluvial ecosystems, having cascading effects on stream conditions and biotic structure. Traditionally, ground-level surveys (e.g. grid and transect analyses) are commonly used for estimating cover of aquatic macrophytes. Nonetheless, this methodological approach is highly time consuming and usually yields information which is practically limited to habitat and sub-reach scales. In contrast, remote-sensing techniques (e.g. satellite imagery and airborne photography), enable collection of large datasets over section, stream and basin scales, in relatively short time and reasonable cost. However, the commonly used spatial high resolution (1m) is often inadequate for examining aquatic vegetation on habitat or sub-reach scales. We examined the utility of a pseudo-spectral methodology, using RGB digital photography for estimating the cover of in-stream vegetation in a small Mediterranean-climate stream. We compared this methodology with that obtained by traditional ground-level grid methodology and with an airborne hyper-spectral remote sensing survey (AISA-ES). The study was conducted along a 2 km section of an intermittent stream (Taninim stream, Israel). When studied, the stream was dominated by patches of watercress (Nasturtium officinale) and mats of filamentous algae (Cladophora glomerata). The extent of vegetation cover at the habitat and section scales (100 and 104 m, respectively) were estimated by the pseudo-spectral methodology, using an airborne Roli camera with a Phase-One P 45 (39 MP) CCD image acquisition unit. The swaths were taken in elevation of about 460 m having a spatial resolution of about 4 cm (NADIR). For measuring vegetation cover at the section scale (104 m) we also used a 'push-broom' AISA-ES hyper-spectral swath having a sensor configuration of 182 bands (350-2500 nm) at elevation of ca. 1,200 m (i.e. spatial resolution of ca. 1 m). Simultaneously, with every swath we used an Analytical Spectral Device (ASD) to measure hyper-spectral signatures (2150 bands configuration; 350-2500 nm) of selected ground-level targets (located by GPS) of soil, water; vegetation (common reed, watercress, filamentous algae) and standard EVA foam colored sheets (red, green, blue, black and white). Processing and analysis of the data were performed over an ITT ENVI platform. The hyper-spectral image underwent radiometric calibration according to the flight and sensor calibration parameters on CALIGEO platform and the raw DN scale was converted into radiance scale. Ground level visual survey of vegetation cover and height was applied at the habitat scale (100 m) by placing a 1m2 netted grids (10x10cm cells) along 'bank-to-bank' transect (in triplicates). Estimates of plant cover obtained by the pseudo-spectral methodology at the habitat scale were 35-61% for the watercress, 0.4-25% for the filamentous algae and 27-51% for plant-free patches. The respective estimates by ground level visual survey were 26-50, 14-43% and 36-50%. The pseudo-spectral methodology also yielded estimates for the section scale (104 m) of ca. 39% for the watercress, ca. 32% for the filamentous algae and 6% for plant-free patches. The respective estimates obtained by hyper-spectral swath were 38, 26 and 8%. Validation against ground-level measurements proved that pseudo-spectral methodology gives reasonably good estimates of in-stream plant cover. Therefore, this methodology can serve as a substitute for ground level estimates at small stream scales and for the low resolution hyper-spectral methodology at larger scales.

Influence of hillslope-channel coupling on two mountain headwater streams, Swiss National Park, Switzerland

NASA Astrophysics Data System (ADS)

Schoch, Anna; Hoffmann, Thomas; Dikau, Richard

2014-05-01

Sediment fluxes in mountain headwater streams are strongly conditioned by sediment supply from hillslopes and thus hillslope-channel coupling, defined as linkages connecting slopes and channels through sediment transport processes. Sediment supply from hillslopes can have major influences on channel characteristics. The main goal of my research is to achieve a better understanding of these influences on mountain headwater streams in two study areas. This is conducted through the investigation of "channel-reach morphology" according to MONTGOMERY AND BUFFINGTON (1997), morphometric and sedimentological characteristics of the channels and analysis of the slope-channel coupling system. The study was conducted in two valleys in the Swiss National Park, i.e. Val dal Botsch (VdB) and Val Mueschauns (VMu). In both headwaters slopes and channel are coupled effectively due to the small spatial vicinity and frequent debris flow processes connecting the two system components. Both catchments were glaciated in the Pleistocene but show contrasting glacial imprints today. While VdB has a V-shaped morphometry that is dominated by unconsolidated sediments (mainly talus and moraine material), VMu is U-shaped in the upper valley segments and the surface is mainly covered with bedrock. Several methods for data collection and analyses were used: (1) Channel-reach morphology classification, (2) DEM-based analysis of long profiles, ksn-values, slope-area plots and measurement of cross sections in the field, (3) investigation of sedimentological characteristics with pebble counts as well as (4) mapping of recent linkages between slopes and channel and determination of connectivity (effectivity of coupling) using a heuristic approach. The results show that sediment input into both headwater streams is dominated by debris flows. The debris flow catchments, as parts of the slope system, have the highest connectivity to the channels. Channel changes are greatest where debris flows cause massive sediment input. Channel changes include an increase in sediment size and density of boulders, a decline in grain roundness and particle sorting as well as slope steepening and alterations of cross sections due to channel incision into the deposited debris flow material. Channel-reach morphology can be modified as well, e.g. from step pool to cascade. The intensity of the influence on channels varies among the investigated debris flows. A comparison of the larger debris flows reveals that debris flows with catchments dominated by bedrock and large areal extend (absolute and relative to main channel drainage area) have the strongest influence on channels. These results suggest that the variable influence on the channel is linked to differences in the Pleistocene glacial imprint of the two study areas. Geomorphic heritage plays a crucial role in recent alpine systems. Reference: MONTGOMERY, D. R. AND J. M. BUFFINGTON (1997): Channel-reach morphology in mountain drainage basins. Geol. Soc. Am. Bull. 109 (5), 596-611.

History, physical effects, and management implications of large organic debris in western Oregon streams.

Treesearch

Frederick Swanson; George W. Lienkaemper; James R. Sedell

1976-01-01

Large organic debris has historically been an important element in small mountain streams of the Pacific Northwest. The debris serves to slow the movement of water and inorganic and fine organic matter through the channel. Debris may remain in the channel for decades or longer, and tends to stabilize some sections of a streambed and stream banks while destabilizing...

Calibration of HYPULSE for hypervelocity air flows corresponding to flight Mach numbers 13.5, 15, and 17

NASA Technical Reports Server (NTRS)

Calleja, John; Tamagno, Jose

1993-01-01

A series of air calibration tests were performed in GASL's HYPULSE facility in order to more accurately determine test section flow conditions for flows simulating total enthalpies in the Mach 13 to 17 range. Present calibration data supplements previous data and includes direct measurement of test section pitot and static pressure, acceleration tube wall pressure and heat transfer, and primary and secondary incident shock velocities. Useful test core diameters along with the corresponding free-stream conditions and usable testing times were determined. For the M13.5 condition, in-stream static pressure surveys showed the temporal and spacial uniformity of this quantity across the useful test core. In addition, finite fringe interferograms taken of the free-stream flow at the test section did not indicate the presence of any 'strong' wave system for any of the conditions investigated.

Filtered cathodic arc deposition apparatus and method

DOEpatents

Krauss, Alan R.

1999-01-01

A filtered cathodic arc deposition method and apparatus for the production of highly dense, wear resistant coatings which are free from macro particles. The filtered cathodic arc deposition apparatus includes a cross shaped vacuum chamber which houses a cathode target having an evaporable surface comprised of the coating material, means for generating a stream of plasma, means for generating a transverse magnetic field, and a macro particle deflector. The transverse magnetic field bends the generated stream of plasma in the direction of a substrate. Macro particles are effectively filtered from the stream of plasma by traveling, unaffected by the transverse magnetic field, along the initial path of the plasma stream to a macro particle deflector. The macro particle deflector has a preformed surface which deflects macro particles away from the substrate.

Ecological Realism of US EPA Experimental Stream Facility ...

EPA Pesticide Factsheets

The USEPA’s Experimental Stream Facility (ESF) conducts meso-scale ecotoxicology studies that account for both structural and functional responses of whole stream communities to contaminants or other stressors. The 16 mesocosms of ESF are indoors and consist of a tiled run section (0.152 m W x 4.268 m L x 0.105 m D) that widens to a gravel riffle section (0.305 m W x 4.268 m L x 0.19 m D). They are intermediate size among studies reporting stream mesocosm results. Their set-up is unique for their size, with a high degree of engineering controls for continuous flow-through dose-response designs, yet fixed, chronic exposures to contaminants under conditions that quantifiably mimic real stream riffle/run habitat with consistent upstream renewal. With fifty standard operating procedures serving ESF studies, the background and boundary condition information is collected to determine the realism critical to the field relevance of the results. Parallel ex situ and in situ single species exposure formats including fish survival and fecundity metrics are also included. With this framework studies at ESF provide scientifically defensible evaluation of proposed aquatic life criteria. This presentation discusses the relevance and realism of USEPA's mesocosms studies conducted using the Experimental Stream Facility in Milford, OH within the context of understanding the role meso-scale results can play in validating aquatic life criteria for streams and, more generally, man

An Interpretation of the Laminar-Turbulent Transition Startup against the Consideration of the Transverse Viscosity Factor

NASA Astrophysics Data System (ADS)

Kolodezhnov, V. N.

2018-03-01

This paper proposes a rheological model of a fluid having the Newtonian model applicability limit and a potential for further “addition” of the transverse viscosity factor. The dynamic equations for a fluid that has such rheological model are discussed, the analysis of which demonstrates the possibility of “generating” the cross stream velocity components. The transition to the dimensionless notation introduces four dimensionless complexes of local characterization for the transition conditions in the neighborhood of the flow region point in question. Based on such dimensionless complexes and using the known experimental data, the empiric conditions of “generating” the cross stream velocity components and starting the laminar-turbulent transition are proposed.

Debris Flows and Road Damage Following a Wildfire in 2014 on the Klamath National Forest, Northern California, Near the Community of Seiad, CA

NASA Astrophysics Data System (ADS)

De La Fuente, J. A.; Mikulovsky, R. P.

2016-12-01

Wildfires in summer 2014 burned more than 200,000 acres on the Klamath National Forest in Northern California, east of Seiad, CA. Much of the area burned at high and moderate severity, and is underlain by Slinkard Pluton granitic rock. During winter 2014-2015, there were a few debris flows in small streams, and some clogged culverts on the road system, but overall road damage was minor. In July of 2015, a strong convective storm triggered several large debris flows, including East Fork Walker and No Name Creeks. These and other debris flows damaged road stream crossings, and delivered a large volume of sediment to the stream network. LiDAR differencing is being used to identify and quantify erosion and deposition from that storm. Field inventories revealed widespread rills and small gullies on steep, burned hillslopes, particularly where underlain by granitic rock. Resulting debris flows were of the sediment bulking variety, and no landslide-triggered debris flows were observed. This may be because intense summer storms are of short duration, and are unlikely to saturate the surface mantle, due also to water repellant soil conditions. It is unknown if erosion during the first winter affected the response to the July storm. Storms around January 17, 2016 initiated many road fill failures, and most were limited to the outer half of the road. Field investigations revealed that granitic road fills failed in a variety of settings, including planar hillslopes, on the flanks of ridges, channel crossings, and at road dips. In virtually all cases, vegetation on the fills, up to 50 years old, had been killed by the 2014 fire. Some fills developed small cracks and scarps, whereas others failed catastrophically as debris slides/flows. Few sediment-bulking debris flows were observed in January, 2016. Road damage exceeded two million dollars, and qualified for Emergency Relief Federally Owned funding (ERFO). The effects of the July, 2015 storm were dominated by sheet wash, rilling, flooding, and debris flows, and road damage was concentrated at stream crossings. In contrast, storms in winter 2015-2016 produced many road fill failures, often far from stream crossings, and these were probably associated with deeper saturation of the regolith. Thus, it is critical that road repair measures address both overland flow and saturation responses.

Environmental controls of wood entrapment in upper Midwestern streams

USGS Publications Warehouse

Merten, Eric C.; Finlay, Jacques; Johnson, Lucinda; Newman, Raymond; Stefan, Heinz; Vondracek, Bruce C.

2011-01-01

Wood deposited in streams provides a wide variety of ecosystem functions, including enhancing habitat for key species in stream food webs, increasing geomorphic and hydraulic heterogeneity and retaining organic matter. Given the strong role that wood plays in streams, factors that influence wood inputs, retention and transport are critical to stream ecology. Wood entrapment, the process of wood coming to rest after being swept downstream at least 10 m, is poorly understood, yet important for predicting stream function and success of restoration efforts. Data on entrapment were collected for a wide range of natural wood pieces (n = 344), stream geomorphology and hydraulic conditions in nine streams along the north shore of Lake Superior in Minnesota. Locations of pieces were determined in summer 2007 and again following an overbank stormflow event in fall 2007. The ratio of piece length to effective stream width (length ratio) and the weight of the piece were important in a multiple logistic regression model that explained 25% of the variance in wood entrapment. Entrapment remains difficult to predict in natural streams, and often may simply occur wherever wood pieces are located when high water recedes. However, this study can inform stream modifications to discourage entrapment at road crossings or other infrastructure by applying the model formula to estimate the effective width required to pass particular wood pieces. Conversely, these results could also be used to determine conditions (e.g. pre-existing large, stable pieces) that encourage entrapment where wood is valued for ecological functions.

Mineralogy of Interplanetary Dust Particles from the Comet Giacobini-Zinner Dust Stream Collections

NASA Technical Reports Server (NTRS)

Nakamura-Messenger, K.; Messenger, S.; Westphal, A. J.; Palma, R. L.

2015-01-01

The Draconoid meteor shower, originating from comet 21P/Giacobini-Zinner, is a low-velocity Earth-crossing dust stream that had a peak anticipated flux on Oct. 8, 2012. In response to this prediction, NASA performed dedicated stratospheric dust collections to target interplanetary dust particles (IDPs) from this comet stream on Oct 15-17, 2012 [3]. Twelve dust particles from this targeted collection were allocated to our coordinated analysis team for studies of noble gas (Univ. Minnesota, Minnesota State Univ.), SXRF and Fe-XANES (SSL Berkeley) and mineralogy/isotopes (JSC). Here we report a mineralogical study of 3 IDPs from the Draconoid collection..

High-efficiency electrochemical thermal energy harvester using carbon nanotube aerogel sheet electrodes

PubMed Central

Im, Hyeongwook; Kim, Taewoo; Song, Hyelynn; Choi, Jongho; Park, Jae Sung; Ovalle-Robles, Raquel; Yang, Hee Doo; Kihm, Kenneth D.; Baughman, Ray H.; Lee, Hong H.; Kang, Tae June; Kim, Yong Hyup

2016-01-01

Conversion of low-grade waste heat into electricity is an important energy harvesting strategy. However, abundant heat from these low-grade thermal streams cannot be harvested readily because of the absence of efficient, inexpensive devices that can convert the waste heat into electricity. Here we fabricate carbon nanotube aerogel-based thermo-electrochemical cells, which are potentially low-cost and relatively high-efficiency materials for this application. When normalized to the cell cross-sectional area, a maximum power output of 6.6 W m−2 is obtained for a 51 °C inter-electrode temperature difference, with a Carnot-relative efficiency of 3.95%. The importance of electrode purity, engineered porosity and catalytic surfaces in enhancing the thermocell performance is demonstrated. PMID:26837457

The σ-Capricornids complex of near-Earth objects

NASA Astrophysics Data System (ADS)

Babadzhanov, P. B.; Kokhirova, G. I.; Khamroev, U. Kh.

2015-04-01

The Earth-crossing asteroids 2008BO16, 2011EC41, and 2013CT36 have very similar orbits according to the Southworth and Hawkins DSH criterion. Their orbits are additionally classified as comet-like based on using the Tisserand parameter which is a standard tool used to distinction between asteroids and comets. The orbital evolution research shows that they cross the Earth's orbit four times over one cycle of the perihelion argument variations. Consequently, a meteoroid stream, possibly associated with them, may produce four meteor showers. Theoretic parameters of the predicted showers were calculated and identified with the observable nighttime σ-Capricornids and χ-Sagittariids, and daytime χ-Capricornids and Capricornids-Sagittariids meteor showers. The similar comet-like orbits and the linkage with the same meteoroid stream producing four active showers provide strong evidence that these asteroids have a common cometary origin. Earlier, it was demonstrated that the Earth-crossing asteroids (2101) Adonis and 1995CS, being a potentially hazardous asteroid (PHA), were recognized as dormant comets because of their linkage with the σ-Capricornids meteoroid stream. Thus, a conclusion was made, that either the considered objects are large pieces of the Adonis, or all five objects are extinct or dormant fragments of a larger comet that was the parent body of the σ-Capricornids meteoroid stream, and whose break-up occurred several tens of thousands years ago. During 2010-2011, three σ-Capricornids fireballs were captured by the Tajikistan fireball network. Taking into account the observations in Canada and the USA, the dynamic and physical properties of the σ-Capricornid meteoroids were identified. According to the estimated meteoroids bulk density a non-homogeneous compound of the σ-Capricornids shower comet-progenitor was suggested.

Fragmentation alters stream fish community structure in dendritic ecological networks.

PubMed

Perkin, Joshuah S; Gido, Keith B

2012-12-01

Effects of fragmentation on the ecology of organisms occupying dendritic ecological networks (DENs) have recently been described through both conceptual and mathematical models, but few hypotheses have been tested in complex, real-world ecosystems. Stream fishes provide a model system for assessing effects of fragmentation on the structure of communities occurring within DENs, including how fragmentation alters metacommunity dynamics and biodiversity. A recently developed habitat-availability measure, the "dendritic connectivity index" (DCI), allows for assigning quantitative measures of connectivity in DENs regardless of network extent or complexity, and might be used to predict fish community response to fragmentation. We characterized stream fish community structure in 12 DENs in the Great Plains, USA, during periods of dynamic (summer) and muted (fall) discharge regimes to test the DCI as a predictive model of fish community response to fragmentation imposed by road crossings. Results indicated that fish communities in stream segments isolated by road crossings had reduced species richness (alpha diversity) relative to communities that maintained connectivity with the surrounding DEN during summer and fall. Furthermore, isolated communities had greater dissimilarity (beta diversity) to downstream sites notisolated by road crossings during summer and fall. Finally, dissimilarity among communities within DENs decreased as a function of increased habitat connectivity (measured using the DCI) for summer and fall, suggesting that communities within highly connected DENs tend to be more homogeneous. Our results indicate that the DCI is sensitive to community effects of fragmentation in riverscapes and might be used by managers to predict ecological responses to changes in habitat connectivity. Moreover, our findings illustrate that relating structural connectivity of riverscapes to functional connectivity among communities might aid in maintaining metacommunity dynamics and biodiversity in complex dendritic ecosystems.

30 CFR 816.57 - Hydrologic balance: Activities in or adjacent to perennial or intermittent streams.

Code of Federal Regulations, 2012 CFR

2012-07-01

... or adjacent to perennial or intermittent streams. (a)(1) Buffer requirement. Except as provided in... section 402 or 404 of the Clean Water Act. (b) Exception. The buffer requirement of paragraph (a) of this...

30 CFR 816.57 - Hydrologic balance: Activities in or adjacent to perennial or intermittent streams.

Code of Federal Regulations, 2014 CFR

2014-07-01

... or adjacent to perennial or intermittent streams. (a)(1) Buffer requirement. Except as provided in... section 402 or 404 of the Clean Water Act. (b) Exception. The buffer requirement of paragraph (a) of this...

Empirical flow parameters - a tool for hydraulic model validity assessment.

DOT National Transportation Integrated Search

2013-08-01

Data in Texas from the U.S. Geological Survey (USGS) physical stream flow and channel property measurements for gaging stations in the state of Texas were used to construct relations between observed stream flow, topographic slope, mean section veloc...

El-Niño/Southern Oscillation (ENSO) influences on monthly NO 3 load and concentration, stream flow and precipitation in the Little River Watershed, Tifton, Georgia (GA)

NASA Astrophysics Data System (ADS)

Keener, V. W.; Feyereisen, G. W.; Lall, U.; Jones, J. W.; Bosch, D. D.; Lowrance, R.

2010-02-01

SummaryAs climate variability increases, it is becoming increasingly critical to find predictable patterns that can still be identified despite overall uncertainty. The El-Niño/Southern Oscillation is the best known pattern. Its global effects on weather, hydrology, ecology and human health have been well documented. Climate variability manifested through ENSO has strong effects in the southeast United States, seen in precipitation and stream flow data. However, climate variability may also affect water quality in nutrient concentrations and loads, and have impacts on ecosystems, health, and food availability in the southeast. In this research, we establish a teleconnection between ENSO and the Little River Watershed (LRW), GA., as seen in a shared 3-7 year mode of variability for precipitation, stream flow, and nutrient load time series. Univariate wavelet analysis of the NINO 3.4 index of sea surface temperature (SST) and of precipitation, stream flow, NO 3 concentration and load time series from the watershed was used to identify common signals. Shared 3-7 year modes of variability were seen in all variables, most strongly in precipitation, stream flow and nutrient load in strong El Niño years. The significance of shared 3-7 year periodicity over red noise with 95% confidence in SST and precipitation, stream flow, and NO 3 load time series was confirmed through cross-wavelet and wavelet-coherence transforms, in which common high power and co-variance were computed for each set of data. The strongest 3-7 year shared power was seen in SST and stream flow data, while the strongest co-variance was seen in SST and NO 3 load data. The strongest cross-correlation was seen as a positive value between the NINO 3.4 and NO 3 load with a three-month lag. The teleconnection seen in the LRW between the NINO 3.4 index and precipitation, stream flow, and NO 3 load can be utilized in a model to predict monthly nutrient loads based on short-term climate variability, facilitating management in high risk seasons.

Magnetic transit-time flowmeter

DOEpatents

Forster, George A.

1976-07-06

The flow rate of a conducting fluid in a stream is determined by disposing two permanent-magnet flowmeters in the stream, one downstream of the other. Flow of the conducting fluid causes the generation of both d-c and a-c electrical signals, the a-c comprising flow noise. Measurement of the time delay between similarities in the a-c signals by cross-correlation methods provides a measure of the rate of flow of the fluid.

Ice cover affects the growth of a stream-dwelling fish.

PubMed

Watz, Johan; Bergman, Eva; Piccolo, John J; Greenberg, Larry

2016-05-01

Protection provided by shelter is important for survival and affects the time and energy budgets of animals. It has been suggested that in fresh waters at high latitudes and altitudes, surface ice during winter functions as overhead cover for fish, reducing the predation risk from terrestrial piscivores. We simulated ice cover by suspending plastic sheeting over five 30-m-long stream sections in a boreal forest stream and examined its effects on the growth and habitat use of brown trout (Salmo trutta) during winter. Trout that spent the winter under the artificial ice cover grew more than those in the control (uncovered) sections. Moreover, tracking of trout tagged with passive integrated transponders showed that in the absence of the artificial ice cover, habitat use during the day was restricted to the stream edges, often under undercut banks, whereas under the simulated ice cover condition, trout used the entire width of the stream. These results indicate that the presence of surface ice cover may improve the energetic status and broaden habitat use of stream fish during winter. It is therefore likely that reductions in the duration and extent of ice cover due to climate change will alter time and energy budgets, with potentially negative effects on fish production.

Drainage basins, channels, and flow characteristics of selected streams in central Pennsylvania

USGS Publications Warehouse

Brush, Lucien M.

1961-01-01

The hydraulic, basin, and geologic characteristics of 16 selected streams in central Pennsylvania were measured for the purpose of studying the relations among these general characteristics and their process of development. The basic parameters which were measured include bankfull width and depth, channel slope, bed material size and shape, length of stream from drainage divide, and size of drainage area. The kinds of bedrock over which the streams flow were noted. In these streams the bankfull channel is filled by flows approximating the 2.3-year flood. By measuring the breadth and mean depth of the channel, it was possible to compute the bankfull mean velocity for each of the 119 sampling stations. These data were then used to compute the downstream changes in hydraulic geometry of the streams studied. This method has been called an indirect computation of the hydraulic geometry. The results obtained by the indirect method are similar to those of the direct method of other workers. The basins were studied by examining the relations of drainage area, discharge, and length of stream from drainage divide. For the streams investigated, excellent correlations were found to exist between drainage area and the 2.3-year flood, as well as between length of stream from the basin divide and drainage area. From these correlations it is possible to predict the discharge for the 2.3-year flood at any arbitrary point along the length of the stream. The long, intermediate, and short axes of pebbles sampled from the bed of the stream were recorded to study both size and sphericity changes along individual streams and among the streams studied. No systematic downstream changes in sphericity were found. Particle size changes are erratic and show no consistent relation to channel slope. Particle size decreases downstream in many streams but remains constant or increases in others. Addition of material by tributaries is one factor affecting particle size and another is the parent material. Wear does not appear to account for some of the changes noted in particle size in a downstream direction. Comparison with laboratory studies indicates that at least in some streams the downstream decrease in size is much greater than would be expected from wear alone. The type of bedrock underlying the channels included in this study appears to affect both channel slope and particle size. For a given length of stream, a stream channel underlain by sandstone tends to have a steeper slope and larger bed material than channels underlain by shale or limestone. Hence, a stream which heads in sandstone and ends in limestone tends to have a more rapid decrease in slope and particle size than a stream heading in limestone and ending in sandstone. The association of steep slopes and small particles for limestone channels implies that slope and particle size may show a vague correlation between lithologic groups although no correlation may exist within a given lithologic type. In addition to the effect of bedrock on slope and particle size, there is some evidence that channels in limestone or dolomite have a slightly smaller cross section at bankfull stage than channels in shale or sandstone. Near the headwaters of many of these streams, a deposit of periglacial rubble affects the slope and bed material size. Some of the debris contains residual boulders which are too large to be moved by ordinary floods and, therefore, impose larger particle sizes in the bed of the stream. The addition of this very coarse debris to the bed material is another example of the influence of geologic factors on stream channels even though the channel consists of unconsolidated debris instead of bedrock. The influence of geologic factors noted in selected streams in central Pennsylvania may not be directly applicable to areas other than the Appalachian Mountains, but the general process is no doubt similar in most areas. In large alluvial valleys bedrock cannot be much of an influencing factor; yet large, thick alluvial deposits and terraces are in a sense "bedrock" materials upon which the stream works to form the landscape.

Invasive European bird cherry disrupts stream-riparian linkages: effects on terrestrial invertebrate prey subsidies for juvenile coho salmon

USGS Publications Warehouse

Roon, David A.; Wipfli, Mark S.; Wurtz, Tricia L.; Blanchard, Arny L.

2016-01-01

The spread of invasive species in riparian forests has the potential to affect both terrestrial and aquatic organisms linked through cross-ecosystem resource subsidies. However, this potential had not been explored in regards to terrestrial prey subsidies for stream fishes. To address this, we examined the effects of an invasive riparian tree, European bird cherry (EBC, Prunus padus), spreading along urban Alaskan salmon streams, by collecting terrestrial invertebrates present on the foliage of riparian trees, their subsidies to streams, and their consumption by juvenile coho salmon (Oncorhynchus kisutch). Riparian EBC supported four to six times less terrestrial invertebrate biomass on its foliage and contributed two to three times lower subsidies relative to native deciduous trees. This reduction in terrestrial invertebrate biomass was consistent between two watersheds over 2 years. In spite of this reduction in terrestrial prey resource input, juvenile coho salmon consumed similar levels of terrestrial invertebrates in stream reaches bordered by EBC. Although we did not see ecological effects extending to stream salmonids, reduced terrestrial prey subsidies to streams are likely to have negative consequences as EBC continues to spread.

Developing flow in S-shaped ducts. 2: Circular cross-section duct

NASA Technical Reports Server (NTRS)

Taylor, A. M. K. P.; Whitelaw, J. H.; Yianneskis, M.

1984-01-01

Laser-Doppler velocimetry measured the laminar and turbulent streamwise flow in a S-duct. The wall pressure distribution and one component of cross-stream velocity were also obtained for the turbulent flow case. Boundary layers near the duct inlet were about 25 percent of the hydraulic diameter in the laminar flow and varied around the periphery of the pipe between 10 percent and 20 percent in turbulent flow. Pressure-driven secondary flows develop in the first half of the S-duct and are attenuated and reversed in the second half. For both Reynolds numbers there is a region near the outer wall of the second half of the duct where the sign of the radial vorticity results in an enforcement of the secondary flow which was established in the first half of the S-duct. The core flow migrates, for both Reynolds numbers, to the outside wall of the first half and lies towards the inside wall of the second half of the S-duct at the outlet. The thinner inlet boundary layers in the turbulent flow give rise to weaker secondary motion.

Flow through triple helical microchannel

NASA Astrophysics Data System (ADS)

Rajbanshi, Pravat; Ghatak, Animangsu

2018-02-01

Flow through helical tubes and channels have been examined in different contexts, for facilitating heat and mass transfer at low Reynolds number flow, for generating plug flow to minimize reactor volume for many reactions. The curvature and torsion of the helices have been shown to engender secondary flow in addition to the primary axial flow, which enhances passive in-plane mixing between different fluid streams. Most of these studies, however, involve a single spiral with circular cross-section, which in essence is symmetric. It is not known, however, how the coupled effect of asymmetry of cross-section and the curvature and torsion of channel would affect the flow profile inside such tubes or channels. In this context, we have presented here the analysis of fluid flow at low Reynolds number inside a novel triple helical channel that consists of three helical flow paths joined along their contour length forming a single channel. We have carried out both microparticle image velocimetry (micro-PIV) and 3D simulation in FLUENT of flow of a Newtonian fluid through such channels. Our analysis shows that whereas in conventional single helices, the secondary flow is characterized by two counter-rotating vortices, in the case of triple helical channels, number of such vortices increases with the helix angle. Such flow profile is expected to enhance possibility of mixing between the liquids, yet diminish the pressure drop.

Simulating nitrate response functions in watersheds: Case studies in the United States and New Zealand

NASA Astrophysics Data System (ADS)

Gusyev, Maksym; Abrams, Daniel; Morgenstern, Uwe; Stewart, Michael

2016-04-01

Non-point sources of nitrate contamination are a common concern in different parts of the world and are difficult to characterize. Due to the solubility of nitrate, it easily enters groundwater and may take years or decades to completely flush to a stream. During this time, it may undergo denitrification, in particular if dissolved oxygen levels are low, requiring a representation of spatially distributed nitrate input as well as detailed hydrogeology. In this presentation, nitrate response functions are generated with four different methodologies that are listed in the order of decreasing degrees of freedom: groundwater flow and chemical transport (MODFLOW/MT3D), groundwater flow with solute particle tracing (MODFLOW/MODPATH), cross-sectional groundwater flow model (MODFLOW), and lumped parameter models (LPMs). We tested these approaches in selected watersheds in the Eastern and Midwestern United States as well as New Zealand and found similar nitrate results in all cases despite different model complexities. It is noted that only the fully three dimensional MODFLOW models with MT3D or MODPATH could account for detailed patterns of land use and nitrate applications; the cross-sectional models and lumped parameter models could only do so approximately. Denitrification at depth could also be explicitly accounted for in all four approaches, although this was not a major factor in any of the watersheds investigated.

Flame Structure of Vitiated Fuel-Rich Inverse Diffusion Flames in a Cross-Flow (Postprint)

DTIC Science & Technology

2011-12-01

downstream of the slot. The flame length increases as the blowing ratio increases as a result of the greater mass of air which reacts. Ignition of...attributed to the greater penetration of the jet into the cross-stream. It is noted that the flame lengths are similar for the different blowing ratios

Making and Breaking Stereotypes: East Asian International Students' Experiences with Cross-Cultural/Racial Interactions

ERIC Educational Resources Information Center

Ritter, Zachary Stephen

2013-01-01

In response to recent budget cuts and declining revenue streams, American colleges and universities are admitting larger numbers of international students. These students add a great deal of cultural and intellectual diversity to college campuses, but they also bring racial stereotypes that can affect cross-racial interaction as well as campus…

Semidiscrete Galerkin modelling of compressible viscous flow past a circular cone at incidence. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Meade, Andrew James, Jr.

1989-01-01

A numerical study of the laminar and compressible boundary layer, about a circular cone in a supersonic free stream, is presented. It is thought that if accurate and efficient numerical schemes can be produced to solve the boundary layer equations, they can be joined to numerical codes that solve the inviscid outer flow. The combination of these numerical codes is competitive with the accurate, but computationally expensive, Navier-Stokes schemes. The primary goal is to develop a finite element method for the calculation of 3-D compressible laminar boundary layer about a yawed cone. The proposed method can, in principle, be extended to apply to the 3-D boundary layer of pointed bodies of arbitrary cross section. The 3-D boundary layer equations governing supersonic free stream flow about a cone are examined. The 3-D partial differential equations are reduced to 2-D integral equations by applying the Howarth, Mangler, Crocco transformations, a linear relation between viscosity, and a Blasius-type of similarity variable. This is equivalent to a Dorodnitsyn-type formulation. The reduced equations are independent of density and curvature effects, and resemble the weak form of the 2-D incompressible boundary layer equations in Cartesian coordinates. In addition the coordinate normal to the wall has been stretched, which reduces the gradients across the layer and provides high resolution near the surface. Utilizing the parabolic nature of the boundary layer equations, a finite element method is applied to the Dorodnitsyn formulation. The formulation is presented in a Petrov-Galerkin finite element form and discretized across the layer using linear interpolation functions. The finite element discretization yields a system of ordinary differential equations in the circumferential direction. The circumferential derivatives are solved by an implicit and noniterative finite difference marching scheme. Solutions are presented for a 15 deg half angle cone at angles of attack of 5 and 10 deg. The numerical solutions assume a laminar boundary layer with free stream Mach number of 7. Results include circumferential distribution of skin friction and surface heat transfer, and cross flow velocity distributions across the layer.

Biological Agents Influencing Physical Process in a Stream: A Case Study in Response to Human-Induced Alteration

NASA Astrophysics Data System (ADS)

Sondossi, H. A.; Bienz, C.

2013-12-01

We present a case study of the Upper Williamson River, a major tributary to Upper Klamath Lake (UKL), to demonstrate illustrate the importance of biophysical interactions. The Klamath River is called 'the upside-down river' by some, due to its peculiar longitudinal profile--low-gradient at the headwaters east of the Cascade Range and steeper close to the mouth as it crosses the Cascades. The Upper Williamson River, as with other tributaries of UKL, flows through highly erodible volcanic ash (pumice) deposits of the Mazama eruption ~7,000 years ago, which created Crater Lake. There is little or no gravel in the broad, shallow alluvial valley of the River. We make the case that in this particular setting, the role of biological agents (e.g., riparian vegetation) is even more prominent than in settings with normal silica-derived sediment. Therefore, typical agricultural practices (removal of woody riparian vegetation, livestock grazing and trampling, etc.) cause rapid and severe channel response and therefore habitat degradation. However, when appropriately restored the recovery is also rapid and drastic. This spring-fed stream with few tributaries in the study area conveys relatively stable discharge, and has good water quality particularly in the upper reaches. It historically supported a population of native redband trout (Oncorhynchus mykiss gairdnerii), and the candidate species (for listing under the Endangered Species Act) Oregon spotted frog (Rana pretiosa) and countless other avian species. In the late 20th Century, after decades of heavy grazing and active removal of willows from the floodplain, the River banks were nearly bare and unstable. The channel was wide, shallow, and smooth. Consequently, poor water quality, particularly high temperature rendered the stream extremely poor habitat. With controlled grazing, re-establishment of willow galleries, and addition of large woody debris (LWD) the channel has recovered to a narrower, deeper cross-section, with ample depth variability. Water quality has improved to the point that it supports a healthy and expanding population of redband trout alongside introduced eastern brook trout (Salvelinus fontinalis). There have been no sightings of Oregon spotted frog yet, but the habitat is deemed suitable.

Integration and segregation in auditory streaming

NASA Astrophysics Data System (ADS)

Almonte, Felix; Jirsa, Viktor K.; Large, Edward W.; Tuller, Betty

2005-12-01

We aim to capture the perceptual dynamics of auditory streaming using a neurally inspired model of auditory processing. Traditional approaches view streaming as a competition of streams, realized within a tonotopically organized neural network. In contrast, we view streaming to be a dynamic integration process which resides at locations other than the sensory specific neural subsystems. This process finds its realization in the synchronization of neural ensembles or in the existence of informational convergence zones. Our approach uses two interacting dynamical systems, in which the first system responds to incoming acoustic stimuli and transforms them into a spatiotemporal neural field dynamics. The second system is a classification system coupled to the neural field and evolves to a stationary state. These states are identified with a single perceptual stream or multiple streams. Several results in human perception are modelled including temporal coherence and fission boundaries [L.P.A.S. van Noorden, Temporal coherence in the perception of tone sequences, Ph.D. Thesis, Eindhoven University of Technology, The Netherlands, 1975], and crossing of motions [A.S. Bregman, Auditory Scene Analysis: The Perceptual Organization of Sound, MIT Press, 1990]. Our model predicts phenomena such as the existence of two streams with the same pitch, which cannot be explained by the traditional stream competition models. An experimental study is performed to provide proof of existence of this phenomenon. The model elucidates possible mechanisms that may underlie perceptual phenomena.

Channel Incision Driven by Suburbanization: Impacts to Riparian Groundwater Flow and Overbank Flow Frequency

NASA Astrophysics Data System (ADS)

Bowles, C. J.; Lawrence, R. L.; Noll, C.; Hancock, G. S.

2005-12-01

Channel incision is a widely observed response to increased flow in urbanized watersheds, but the effects of channel lowering on riparian water tables is not well documented. In a rapidly incising suburban stream in the Virginia Coastal Plain, we hypothesize that stream incision has lowered floodplain water tables and decreased the overbank flow frequency. The monitored stream is a tributary to the James River draining 1.3 km2 of which 15% is impervious cover. Incision has occurred largely through upstream migration of a one meter high knickpoint at a rate of ~1.5 m/yr, primarily during high flow events. We installed 63 wells in six stream-perpendicular transects as well as a cluster of wells around the knickpoint to assess water table elevations beneath the floodplain adjacent to the incising stream. Two transects are located 30 and 50 m upstream of the knickpoint in the unincised floodplain, and the remainder are 5, 30, 70, and 100 m downstream in the incised floodplain. In one transect above and two below, pressure transducers attached to dataloggers provide a high-resolution record of water table changes. Erosion pins were installed and channel cross-sections surveyed to determine streambed stability. Significant differences are observed in bank morphology and groundwater flow above vs. below the knickpoint. Above the knickpoint, the banks are stable, ~3 m wide, and ~0.3 m deep, and widen and deepen slightly toward the knickpoint. The water table is relatively flat and is 0.2-0.4 m below the floodplain surface, and groundwater contours suggest flow is parallel to the stream direction. The water table responds immediately to precipitation events, and rises to the floodplain surface in significant rainfall events. Immediately downstream of the knickpoint, channel width increases by about a meter, and stream depth increases to ~1.5 meters. The water table immediately below the knickpoint possesses a steep gradient, and is up to one meter below the floodplain surface. Groundwater flow is redirected toward the stream. Moving downstream banks continue to widen, and the channel is up to 8 m wide and ~1.3 m deep ~100 m below the current knickpoint position. In the most downstream transects, the water table slopes gently toward the stream and remains ~1 m below the floodplain surface, equivalent to the depth of incision generated by knickpoint passage. Upstream of the knickpoint, overbank flooding occurs frequently, while below the knickpoint the majority of storm flow is contained within the incised channel and occupation of the floodplain is rare. The impact of incision to the riparian water table is dramatic, with a lowered water table and redirection of groundwater flow toward the stream. The incision is driven by suburbanization upstream of this riparian corridor, and has likely reduced the ability of this protected riparian system to improve the water quality of the suburban runoff that passes through it.

Flow effects on benthic stream invertebrates and ecological processes

NASA Astrophysics Data System (ADS)

Koprivsek, Maja; Brilly, Mitja

2010-05-01

Flow is the main abiotic factor in the streams. Flow affects the organisms in many direct and indirect ways. The organisms are directly affected by various hydrodynamic forces and mass transfer processes like drag forces, drift, shear stress, food and gases supply and washing metabolites away. Indirect effects on the organisms are determining and distribution of the particle size and structure of the substrate and determining the morphology of riverbeds. Flow does not affect only on individual organism, but also on many ecological effects. To expose just the most important: dispersal of the organisms, habitat use, resource acquisition, competition and predator-prey interactions. Stream invertebrates are adapted to the various flow conditions in many kinds of way. Some of them are avoiding the high flow with living in a hyporeic zone, while the others are adapted to flow with physical adaptations (the way of feeding, respiration, osmoregulation and resistance to draught), morphological adaptations (dorsoventrally flattened shape of organism, streamlined shape of organism, heterogeneous suckers, silk, claws, swimming hair, bristles and ballast gravel) or with behaviour. As the flow characteristics in a particular stream vary over a broad range of space and time scales, it is necessary to measure accurately the velocity in places where the organisms are present to determine the actual impact of flow on aquatic organisms. By measuring the mean flow at individual vertical in a single cross-section, we cannot get any information about the velocity situation close to the bottom of the riverbed where the stream invertebrates are living. Just measuring the velocity near the bottom is a major problem, as technologies for measuring the velocity and flow of natural watercourses is not adapted to measure so close to the bottom. New researches in the last two decades has shown that the thickness of laminar border layer of stones in the stream is only a few 100 micrometers, what is not enough to make a shelter for stream invertebrates. It serves as a shelter only for microorganisms, but the stream invertebrates have to avoid the swift flow or adapt to flow with adaptations described above. To understand what conditions are subject to aquatic organisms and how to adapt, it is essential. Both, knowledge of fluid dynamics in natural watercourses and ecology are needed to understand to what conditions the stream invertebrates are exposed and how they cope with them. Some investigations of near bed flow will be performed on the Glinšica stream. The acoustic Doppler velocimeter SonTek will be adapted to measure so close to the bed as possible. It is expected we should be able to measure the velocities just 0,5 cm above the bed surface. We intend to measure the velocities on a natural and on a regulated reach and then compare the results.

30 CFR 817.57 - Hydrologic balance: Surface activities in or adjacent to perennial or intermittent streams.

Code of Federal Regulations, 2014 CFR

2014-07-01

... activities in or adjacent to perennial or intermittent streams. (a)(1) Buffer requirement. Except as provided... section 402 or 404 of the Clean Water Act. (b) Exception. The buffer requirement of paragraph (a) of this...