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Sample records for gravels wad ghoweiba

  1. Acute whiplash associated disorders (WAD).

    PubMed

    Pastakia, Khushnum; Kumar, Saravana

    2011-01-01

    Whiplash-associated disorder (WAD) is the term given for the collection of symptoms affecting the neck that are triggered by an accident with an acceleration-deceleration mechanism such as a motor vehicle accident. The incidence of whiplash injury varies greatly between different parts of the world with significant monetary burden on the individual as well as the wider community. Which treatments are best for reducing pain and disability experience in acute WADs? Clinical practice guidelines, systematic reviews, meta-analysis, randomized controlled trials. PubMed, Cochrane Library, Medline, EMBASE, AUST health, AMED. From the patient perspective the main outcomes considered are pain and disability. Whiplash-associated disorders include a range of symptoms related to the neck and head. They commonly occur after motor vehicle accidents or diving mishaps. There is good evidence to suggest that active exercise, acting as usual and combination therapy are the most effective treatment choices in an acute presentation.

  2. Wideband Analog Data System (WADS), system design document

    NASA Technical Reports Server (NTRS)

    Brose, J. F.

    1979-01-01

    The Wideband Analog System (WADS) which performs post flight structural dynamic analysis of wideband FM data recorded during orbital flight tests is defined. Screening, reporting, and plotting steady state and transient wave analysis data are provided by WADS.

  3. Gravel packer

    SciTech Connect

    Zunkel, G.D.; Bolin, M.L.

    1987-01-27

    A retrievable gravel packer is described for placing a gravel pack in a wellbore about a gravel screen disposed therebelow across a producing formation comprising: a gravel packer assembly; a packer element disposed on the exterior of the assembly; J-slot means in the assembly for selectively maintaining the packer element in an unset mode; ratchet means in the assembly for releasably locking the packer element in a set mode; an intake passage in the assembly for receiving fluid from a tubing string in the well bore above and secured to the gravel packer; a return passage for receiving fluid from the interior of the gravel screen; a circulation passage extending from the exterior of the gravel packer below the packer element to the intake passage; closeable crossover means to receive fluid from the return passage and guide the received fluid from the return passage to the exterior of the assembly above the packer element; first check valve means for preventing back flow to the intake passage from the interior of the gravel screen; second check valve means adapted to selectively open the intake passage to the circulation passage in response to a positive pressure differential between the exterior of the gravel packer and the intake passage; and check valve release means for inactivating the second check valve means in response to a fluid pressure buildup in the intake passage thereabove.

  4. Gravel packer

    SciTech Connect

    Zunkel, G.D.

    1986-01-06

    A retrievable gravel packer is described for placing a gravel pack in a wellbore about a gravel screen disposed therebelow across a producing formation comprising: a gravel packer assembly; a packer element disposed on the exterior of the assembly; means in the assembly for selectively maintaining the packer element in an unset mode; means in the assembly for releasably locking the packer element in a set mode; an intake passage in the assembly for receiving fluid from a tubing string in the well bore above and secured to the gravel packer; a return passage in the assembly for receiving fluid from the interior of the gravel screen; a circulation passage extending from the exterior of the gravel packer assembly below the packer element to the intake passage; closeable crossover means to receive fluid from the return passage and guide the received fluid from the return passage to the exterior of the assembly above the packer element; relief ports between the intake passage and the return passage; first valve means for closing the intake passage from the circulation passage; second valve means for opening communication through the relief ports; a check ball at the lower end of the gravel packer; and check ball release means for selectively releasing the check ball from the gravel packer.

  5. Gravel packer

    SciTech Connect

    Zunkel, G.D.

    1987-01-13

    A gravel packer is described for placing a gravel pack in a wellbore about a gravel screen disposed therebelow across a producing formation comprising: a gravel packer assembly; a packer element disposed on the exterior of the assembly; ratchet means in the assembly for releasably locking the packer element in a set mode; an intake passage in the assembly for receiving fluid from a tubing string in the well bore and secured to the gravel packer; a return passage in the assembly for receiving fluid from the interior of the gravel screen; a circulation passage in assembly extending from the exterior of the gravel packer below the packer element to the intake passage; closeable crossover means associated with the assembly to receive fluid from the return passage and guide the received fluid from the return passage to the exterior of the assembly above the packer element; first check valve means in the assembly for preventing flow to the gravel screen through the return passage; second check valve means in the assembly adapted to selectively permit flow from the return passage to the intake passage in response to a positive pressure differential between the return pass and the intake passage; and J-slot means for selectively disconnecting the crossover means from the packer assembly.

  6. Industrial sand and gravel

    USGS Publications Warehouse

    Dolley, T.P.

    2006-01-01

    In 2005, domestic production of industrial sand and gravel was about 31 Mt, a 5% increase from 2004. This increase was bouyed by robust construction and petroleum sectors of the US economy. Based on estimated world production figures, the United States was the world's leading producer and consumer of industrial sand and gravel. In the short term, local shortages of industrial sand and gravel will continue to increase.

  7. Consolidatable gravel pack method

    SciTech Connect

    Friedman, R.H.; Surles, B.W.

    1989-01-31

    A method is described for forming a consolidated gravel pack in a washed-out cavity adjacent to a producing well penetrating a subterranean oil formation comprising the steps of: (a) forming a quantity of resin coated gravel comprising granular mineral particles including gravel, the gravel particles being coated with a resin fluid containing a polymerizable oligomer of furfuryl alcohol resin, a catalyst comprising an oil soluble, very slightly water soluble organic acid and an ester of a weak organic acid to consume water produced by the polymerization of resin, the polymer coated gravel comprising a sticky solid material; (b) preparing an aqueous saline carrier fluid comprising water which is from 70 to 100% saturated with sodium chloride; (c) suspending the resin-coated gravel in the carrier fluid, forming a fluid mixture of resin-coated gravel and carrier fluid; (d) introducing the fluid mixture comprising the resin coated gravel particles suspended in the aqueous saline carrier fluid into the washed-out cavity of the formation adjacent to the producing well and shutting in the well for sufficient period of time to allow polymerization of the resin, forming the permeable gravel pack in the washed-out cavity of the formation.

  8. Prepacking perforations improves gravel packs

    SciTech Connect

    Hall, B.E.; Pace, J.R. )

    1990-05-21

    Productivity can be increased by prepacking perforations with gravel before a major gravel pack is pumped. The main gravel-pack treatment follows immediately after the prepack. This procedure can increase perforation permeability due to a more complete gravel fill of the perforation. The gravel pack prevents perforations from collapsing or filling with formation sand.

  9. Industrial sand and gravel

    USGS Publications Warehouse

    Dolley, T.P.

    2011-01-01

    Domestic production of industrial sand and gravel in 2010 was about 26.5 Mt (29.2 million st), a 6-percent increased from 2009. Certain end uses of industrial sand and gravel, such as sand for container glass, golf course sand, recreational sand, specialty glass and water filtration, showed increased demand in 2010.

  10. Industrial sand and gravel

    USGS Publications Warehouse

    Dolley, T.P.

    2012-01-01

    Domestic production of industrial sand and gravel in 2011 was about 30 Mt (33 million st), increasing slightly compared with 2010. Some important end uses for industrial sand and gravel include abrasives, filtration, foundry, glassmaking, hydraulic fracturing sand (frac sand) and silicon metal applications.

  11. Industrial sand and gravel

    USGS Publications Warehouse

    Dolley, T.P.

    2013-01-01

    Domestic production of industrial sand and gravel in 2012 was about 49.5 Mt (55 million st), increasing 13 percent compared with that of 2011. Some important end uses for industrial sand and gravel include abrasives, filtration, foundry, glassmaking, hydraulic fracturing sand (frac sand) and silicon metal applications.

  12. Reconditioning contaminated gravel

    SciTech Connect

    Walsh, H.; Bowers, J.S.; Cadwell, K.

    1995-02-01

    Lawrence Livermore National Laboratory (LLNL) has developed a portable screening system that will recondition radioactively contaminated gravel in the field. The separation technique employed by this system removes dirt, contaminated debris, and other fine particles from gravel. At LLNL, gravel is used in conjunction with the experimental testing of explosives to reduce shock wave propagation. The gravel surrounds the experimental device and buffers the energy generated from the explosion. During an explosion, some of the gravel is broken down into small particles and mixed with contaminants. Contaminants in the used gravel originate from metal sheathing and other parts comprising, the experimental device. These contaminants may consist of radionuclides and metals that are considered hazardous by the State of California when disposed. This paper describes the process that conveys contaminated material into the screener system, sprays the material with recycled water or other mild cleaning chemicals, and separates particles based on size. Particles greater than a specified size are discharged out of the screener separator and recycled back into use, thereby reducing the amount of mixed waste generated and minimizing the need for new gravel. The fines or silt are flushed out of the separator with the water and are removed from the water and consolidated into a drum with the use of a hydrocyclone separator and drum decant system. Because the water in the spray system is recycled, minimal makeup water is needed. The system monitors pH and total dissolved solids.

  13. Industrial sand and gravel

    USGS Publications Warehouse

    Dolley, T.P.

    2010-01-01

    Domestic production of industrial sand and gravel in 2009 was about 27 Mt (30 million st), declining by 10 percent compared with 2008. Certain end uses of industrial sand and gravel, such as foundry and glassmaking sand, may have declined by a factor greater than 10 percent in 2009. U.S. apparent consumption was 24.7 Mt (27.2 million st) in 2009, down by 10 percent from the previous year, and imports declined to 83 kt (91,000 st).

  14. The Potential Contribution of Stress Systems to the Transition to Chronic WAD

    PubMed Central

    McLean, Samuel A

    2011-01-01

    Study Design A narrative description highlighting preclinical and clinical evidence that physiologic stress systems contribute to WAD pathogenesis. Objective To present several lines of evidence supporting the hypothesis that physiologic stress systems contribute to WAD pathogenesis. Summary of Background Data In addition to subjecting soft tissue to biomechanical strain, a motor vehicle collision (MVC) event is also an acute stressor which activates physiologic stress systems. Increasing data from animal and human studies suggest that the activation of these stress systems may contribute to long lasting changes in pain sensitivity after tissue injury. Methods Non-systematic review of several lines of evidence that together suggest that physiologic systems involved in the stress response may contribute to the development of WAD. Results Stress systems which appear capable of producing hyperalgesia and allodynia include catecholaminergic systems, serotonin systems, and the hypothalamic-pituitary-adrenocortical (HPA) system. Evidence for the role of these systems comes, in part, from studies examining the association between genetic variants and chronic pain outcomes. For example, in a recent study of acute neck pain after MVC, patients with certain genotypes of an enzyme involved in catecholamine metabolism were more than twice as likely to report moderate or severe neck pain in the emergency department. Such pain vulnerability due to stress system function may interact with the effects of biomechanical injury and psychobehavioral responses to influence the development of WAD. Conclusion More research examining the influence of stress systems on WAD are needed. If these systems do influence WAD outcomes, then treatments which diminish the adverse effects of stress systems may be a useful component of multimodal therapeutic interventions for individuals at risk of chronic pain development after MVC. PMID:22020617

  15. Rates of Gravel Dispersion

    NASA Astrophysics Data System (ADS)

    Haschenburger, J. K.

    2010-12-01

    Sediment transfers in gravel-bed rivers involve the three-dimensional dispersion of mixed size sediment. From a kinematics standpoint, few studies are available to inform on the streamwise and vertical rates of sediment dispersion in natural channels. This research uses a gravel tracing program to quantify dispersion rates over 19 flood seasons. Empirical observations come from Carnation Creek, a small gravel-bed river with large woody debris located on the west coast of Vancouver Island, Canada. Frequent floods and the relatively limited armor layer facilitate streambed activity and relatively high bedload transport rates, typically under partial sediment transport conditions. Over 2500 magnetically tagged stones, ranging in size from 16 to 180 mm, were deployed on the bed surface between 1989 and 1992 in four generations. To quantify gravel dispersion over distances up to 2.6 km, observations are taken from 11 recoveries. Over 280 floods capable of moving bedload occurred during this period, with five exceeding the estimated bankfull discharge. Streamwise dispersion is quantified by virtual velocity, while dispersion into the streambed is quantified by a vertical burial rate. The temporal trend in streamwise dispersion rates is described by a power function. Initial virtual velocities decline rapidly from around 1.4 m/hr to approach an asymptote value of about 0.2 m/hr. The rapid change corresponds to a significant increase in the proportion of buried tracers due to vertical mixing. Initial burial rates reflect the magnitude of the first flood after tracer deployment and range from 0.07 to 0.46 cm/hr depending on tracer generation. Burial rates converge to about 0.06 cm/hr after the fourth flood season and then gradually decline to about 0.01 cm/hr. Thus, the rate of streamwise dispersion exceeds that of vertical dispersion by three orders of magnitude when the movement of sediment routinely activated by floods is considered.

  16. Numerical simulation of gravel packing

    SciTech Connect

    Winterfeld, P.H.; Schroeder, D.E. Jr. )

    1992-08-01

    To obtain maximum productivity from unconsolidated formations where sand control is required, it is important to understand the mechanics of gravel packing. This paper describes a finite-element, numerical simulator that can predict gravel placement in the perforations and annulus of a wellbore. The equations for the simulator include mass and momentum conservation. Wellbore geometry, physical properties, and fluid and gravel-pack properties are simulator input. Experiments in a 100-ft full-scale wellbore model for three gravel-packing configurations have been successfully simulated. These configurations are a circulating pack with a washpipe, a squeeze pack, and a circulating/squeeze pack with a washpipe and a lower telltale screen. The low cost, speed, and extrapolation capabilities of the numerical simulator will greatly enhance our ability to predict gravel placement in a wellbore.

  17. Laparoscopic decortication of simple renal cyst with omental wadding technique: single-center experience.

    PubMed

    El-Shazly, Mohamed; Allam, Adel; Hathout, Badawy

    2012-11-01

    What is the impact of the omental wadding technique on decreasing the incidence of recurrence after laparoscopic decortication of the symptomatic simple renal cyst? This is the question we are trying to answer through this study. This is a cohort study of 14 consecutive patients who underwent transperitoneal laparoscopic decortication of a symptomatic simple renal cyst with the omental wadding technique between November 2007 and November 2011. The indication for surgery was for relief of pain in all cases. Pain was assessed preoperatively and at 1 month and every 6 months postoperatively using a pain numerical rating scale. Only simple cysts (Bosniak I and II) more than 10 cm in their greatest dimension were included in this study. Patients with complicated cysts (Bosniak III and IV) and those with cysts less than 10 cm in their greatest dimension were excluded from this study. Patients were 7 men and 7 women with a mean age of 47 years (range, 35-63 years), and the mean body mass index was 27 kg/m(2). Laparoscopic decortication was the primary treatment in 11 cases and the secondary treatment in 3 cases after sclerotherapy. We used the omental wadding technique to try to fill the cavity after decortication to decrease the incidence of recurrence with simple laparoscopic decortication reported in other series. We reviewed the preoperative and postoperative data. The operation was successfully completed laparoscopically in all cases with a mean operative time of 97 minutes without major perioperative complications. Hospital stay was 2.4 days (range, 2-4 days). All cases improved significantly after operation in a mean follow-up of 1.5 years. Using this technique, we did not have any recurrence after surgery. Laparoscopic decortication with omental wadding is helpful to decrease the incidence of simple renal cyst recurrence after laparoscopic decortication.

  18. Influence of sympathetic nervous system on sensorimotor function: whiplash associated disorders (WAD) as a model.

    PubMed

    Passatore, Magda; Roatta, Silvestro

    2006-11-01

    There is increasing interest about the possible involvement of the sympathetic nervous system (SNS) in initiation and maintenance of chronic muscle pain syndromes of different aetiology. Epidemiological data show that stresses of different nature, e.g. work-related, psychosocial, etc., typically characterised by SNS activation, may be a co-factor in the development of the pain syndrome and/or negatively affect its time course. In spite of their clear traumatic origin, whiplash associated disorders (WAD) appear to share many common features with other chronic pain syndromes affecting the musculo-skeletal system. These features do not only include symptoms, like type of pain or sensory and motor dysfunctions, but possibly also some of the pathophysiological mechanisms that may concur to establish the chronic pain syndrome. This review focuses on WAD, particular emphasis being devoted to sensorimotor symptoms, and on the actions exerted by the sympathetic system at muscle level. Besides its well-known action on muscle blood flow, the SNS is able to affect the contractility of muscle fibres, to modulate the proprioceptive information arising from the muscle spindle receptors and, under certain conditions, to modulate nociceptive information. Furthermore, the activity of the SNS itself is in turn affected by muscle conditions, such as its current state of activity, fatigue and pain signals originating in the muscle. The possible involvement of the SNS in the development of WAD is discussed in light of the several positive feedback loops in which it is implicated.

  19. Method for gravel packing wells

    SciTech Connect

    Jones, L.G.

    1990-08-07

    This patent describes a method for gravel packing a well that penetrates an unconsolidated or poorly consolidated subterranean oil or gas reservoir. It comprises: providing a borehole casing through the reservoir; perforating the casing at preselected intervals therealong to form at least one set of longitudinal, perforation tunnels adjacent a substantial portion of the reservoir; locating a sand screen inside the casing and in juxtaposition with the perforation tunnels, an annulus being formed between the sand screen and the casing; positioning a conduit in juxtaposition with the sand screen extending substantially the length of the sand screen and having its upper extremity open to fluids; injecting a fluid slurry containing gravel down through the annulus and conduit whereby the fluid portion of the slurry is forced out of the annulus through the perforation tunnels into the reservoir and the gravel portion of the slurry deposited in the annulus and forced into the perforation tunnels into the formation; sizing the cross-sectional area of the conduit and the annulus so that if gravel forms a bridge in a portion of the annulus thereby blocking the flow of fluid slurry through the the annulus, fluid slurry containing gravel will continue to flow through the conduit and into the annulus around the gravel bridge; and terminating the injection of the slurry.

  20. Concepts in gravel beach dynamics

    NASA Astrophysics Data System (ADS)

    Buscombe, Daniel; Masselink, Gerhard

    2006-11-01

    The dominant processes in gravel beach dynamics are reviewed, highlighting some common themes which unify the various components of the gravel beach system, the repercussions of which impart on how gravel beach dynamics might be understood conceptually. In particular, gravel beach dynamics are thought to be highly dependent on the temporal and spatial variation in grain size, and the continual adjustments made by an active beach step, both of which act not only as the expression of changing morphodynamic conditions, but also as a controlling influence. Morphodynamics, the notion that the exchanges on beaches between the hydrodynamics, sediment transport, and morphological change takes the form of reciprocal relationships which are mediated through feedback mechanisms (in such a way that they cannot be thought of or studied independently) is not a new one. Yet it appears that for the gravel beach, morphodynamics must be re-defined to describe conditions where variations in sediment size are thought to deserve parity, rather than as merely a sequent entity or boundary condition. 'Morpho-sedimentary-dynamics' is a phrase coined to intuit such cause and effect, detailing the co-evolution of morphology, hydro-hydraulics and sediment properties whilst acknowledging causative pluralism, feedbacks and multiplier effects. This is the recommended conceptual framework within which to crystallise thought and organise further research for the gravel beach. Essentially, it increases the minimum number of parameters needed to describe the state of the gravel beach as a physical system. Therefore, it is advised that simplicity will be most expedient in our future modelling efforts, if complexity is to be adequately encapsulated.

  1. Method for staged placement of gravel packs

    SciTech Connect

    Davis, B.E.

    1990-04-10

    This patent describes a process for gravel packing in a wellbore annulus including a well screen and perforations extending into a producing formation. It comprises: providing an initial gravel pack carrier fluid at below formation fracturing pressure and having a gravel loading of up to about five pounds gravel per gallon of carrier fluid within the wellbore annulus, providing additional amounts of carrier fluid at below fracturing pressure and having gravel loadings which are successively higher than a preceding and the initial gravel loading to the wellbore annulus and continually increasing the gravel loading in the carrier fluid to a range of ten to twenty pounds of gravel per gallon of carrier fluid until the gravel packing of the wellbore annulus is completed.

  2. Designing gravel pack for uranium ISL wells

    NASA Astrophysics Data System (ADS)

    Ber, A. A.; Minaev, K. M.; Ber, L. M.; Isaev, Ye D.; Ulyanova, O. S.

    2016-09-01

    The paper describes the improvement of gravel packing technique applied for the production wells. The authors have suggested new design of gravel pack for gravel packing of productive formations. The issue is currently topical because gravel packing at drillhole ISL is less time- and money-consuming. The subject of the research is gravel pack design and content. The purpose defined by the authors is to design the gravel pack and to suggest the composition of gravel cement agent. As a result of the research, the authors have described different designs of the gravel pack, its optimal shape, as well as a choice and justification of cement agents, a hold cover of the gravel pack, and suggested the methods of experimental research.

  3. Gravel Roads: Maintenance and Design Manual

    EPA Pesticide Factsheets

    This manual was developed with a major emphasis on the maintenance of gravel roads, including some basic design elements. The purpose of the manual is to provide clear and helpful information for doing a better job of maintaining gravel roads.

  4. Methods to measure sedimentation of spawning gravels

    Treesearch

    Thomas E. Lisle; Rand E. Eads

    1991-01-01

    Sediment transport occurring after spawning can cause scour of incubating embryos and infiltration of fine sediment into spawning gravel, decreasing intergravel flow and preventing hatched fry from emerging from the gravel. Documentation of these effects requires measuring gravel conditions before and after high flow periods and combining methods to record scour and...

  5. Intensification and sedentism in the terminal Pleistocene Natufian sequence of el-Wad Terrace (Israel).

    PubMed

    Yeshurun, Reuven; Bar-Oz, Guy; Weinstein-Evron, Mina

    2014-05-01

    Measuring subsistence intensification in the archaeofaunal record has provided strong evidence for socioeconomic shifts related to sedentarization in the terminal Pleistocene Mediterranean Basin, but the precise timing and scale of the intensification trend and its place in the evolution of settled societies remain contentious. New archaeofaunal data from the key Natufian sequence of el-Wad Terrace (Mount Carmel, Israel, ca. 15.0-11.7 ka [thousands of years ago]) is used here to clarify and contextualize paleoeconomy and mobility trends in the latest Pleistocene Levant, representing the culmination of Epipaleolithic subsistence strategies. Taphonomic variables serve as supplementary indicators of habitation function and occupation intensity along the sequence. At el-Wad, a very broad range of animals, mostly small to medium in size, were captured and consumed. Consumption leftovers were discarded in intensively occupied domestic spaces and suffered moderate attrition. The Early (ca. 15.0-13.7/13.0 ka) and Late (ca. 13.7/13.0-11.7 ka) Natufian phases display some differences in prey exploitation and taphonomic markers of occupation intensity, corresponding with other archaeological signals. We further set the intra-Natufian taxonomic and demographic trends in perspective by considering the earlier Epipaleolithic sequence of the same region, the Israeli coastal plain. Consequently, we show that the Early Natufian record constituted an important dietary shift related to greater occupation intensity and sedentarization, rather than a gradual development, and that the Late Natufian record appears to be maintaining, if not amplifying, many of these novel signals. These conclusions are important for understanding the mode and tempo of the transition to settled life in human evolution.

  6. Unfolding with Maxed and Gravel.

    SciTech Connect

    WIEGEL, BURKHARD

    2004-07-12

    Version: 00 UMG (Unfolding with MAXED and GRAVEL) is a package of seven programs written for the analysis of data measured with spectrometers that require the use of unfolding techniques. See the developers’ website for information on training courses http://www.ptb.de/en/org/6/utc2006/intro.htm. The program MAXED applies the maximum entropy principle to the unfolding problem, and the program GRAVEL uses a modified SAND-II algorithm to do the unfolding. There are two versions of each: MXD_FC33 and GRV_FC33 for “few-channel” unfolding (e.g., Bonner sphere spectrometers) and MXD-MC33 and GRV_MC33 for “multi-channel” unfolding (e.g., NE-213). The program IQU can be used to calculate integral quantities for both MAXED and GRAVEL solution spectra and, in the case of MAXED solutions, it can also be used to calculate the uncertainty in these values as well as the uncertainty in the solution spectrum. The uncertainty calculation is handled in the following way: given a solution spectrum generated by MAXED, the program IQU considers variations in the measured data and in the default spectrum and uses standard methods to do sensitivity analysis and uncertainty propagation. There are two versions: IQU_FC33 for “few channel” unfolding and IQU_MC33 for “multi-channel” unfolding. The program UMGPlot can be used to display the results from the unfolding programs MAXED and GRAVEL in graphical form in a quick and easy way.

  7. Offshore sand and gravel mining

    SciTech Connect

    Pandan, J.W.

    1983-05-01

    This paper reviews the status of mining offshore for sand and gravel on a world-wide basis. It discusses the technology for exploration and evaluation of sea floor mineral targets, as well as mining, transportation, and processing. Large operations in Japan and Europe are described, based upon personal observations of the author. The U.S. situation is outlined and opinions offered as to the outlook for the future.

  8. An overview of gravel-packed completions

    SciTech Connect

    Heng, H.B.

    1987-05-01

    Sarawak Shell Bhd./Sabah Shell Petroleum Co. (SSB/SSPC) experience with gravel-packed completions covers some 12 years. During that period, some 290 gravel-packed zones have been completed, and about 400X10/sup 6/ bbl (64X10/sup 6/ m/sup 3/) of oil have been produced through gravel packs in 13 offshore fields. This paper presents an overview of the development of gravel-packing methods, with special reference to the new gravel-packing technique developed in early 1984 for the Bayan field gravel-packed completions. Productivity reduction resulting from gravel packing and the long-term performance of the packs are discussed briefly.

  9. A global drought climatology for the 3rd edition of the World Atlas of Desertification (WAD)

    NASA Astrophysics Data System (ADS)

    Spinoni, Jonathan; Carrao, Hugo; Naumann, Gustavo; Antofie, Tiberiu; Barbosa, Paulo; Vogt, Jürgen

    2013-04-01

    A new version of the World Atlas of Desertification (WAD) is being compiled in the framework of cooperation between the Joint Research Centre (JRC) of the European Commission and the United Nations Environment Programme (UNEP). This initiative aims at mapping the global land degradation and desertification, as well as introducing the reader with complex interactions of geo-physical, socio-economic, and political aspects that affect the environmental sustainability. Recurrent extreme events resulting from climate change, such as more severe droughts, combined with non-adapted land use practices can affect the resilience of ecosystems tipping them into a less productive state. Thus, to describe the effects of climatological hazards on land degradation and desertification processes, we computed a World drought climatology that will be part of the 3rd edition of the WAD and will replace and update to 2010 the results presented in the 2nd edition in 1997. This paper presents the methodology used to compute three parameters included in the WAD drought climatology, i.e. drought frequency, intensity and duration, and discusses their spatio-temporal patterns both at global and continental scales. Because drought is mainly driven and triggered by a rainfall deficit, we chose the Standardized Precipitation Index (SPI) as the drought indicator to estimate our climatological parameters. The SPI is a statistical precipitation-based drought indicator widely used in drought-related studies. We calculated the SPI on three different accumulation periods: 3 months (SPI-3), 6 months (SPI-6), and 12 months (SPI-12), in order to take into account meteorological, agricultural, and hydrological drought-related features. Each quantity has been calculated on a monthly basis using the baseline period between January 1951 and December 2010. As data input, we used the Full Data Reanalysis Version 6.0 (0.5˚x0.5˚) of gridded monthly precipitation provided by the Global Precipitation

  10. Locating subsurface gravel with thermal imagery

    NASA Technical Reports Server (NTRS)

    Scholen, Douglas E.; Clerke, William H.; Luepke, Douglas E.

    1986-01-01

    A method was discussed for using 6 band thermal imagery to locate subsurface gravel deposits in vegetated areas. Geologic history is reviewed to select potential areas of study. An overflight was made using a thermal scanner. The data were processed with a computerized system to delineate areas showing a quartz signature radiated by a gravel deposit. The method was developed during a search for gravel on National Forest land in Louisiana. Processed data from thermal imagery was compared with known gravel deposits and exploratory drill hole logs. A high correlation was noted for a wide range of deposits, from commercial pits to trace deposits only a foot thick. Overburden at these sites varied from zero to sixty feet, near the maximum annual penetration by the thermal wave. It was concluded that the method can be used to locate buried gravel deposits and that more time and effort are needed to verify the usefulness for developing gravel pits adjacent to proposed construction sites.

  11. Method of gravel packing a subterranean well

    SciTech Connect

    Not Available

    1991-11-05

    This patent describes a method of gravel packing a well bore penetrating a subterranean formation. It comprises blocking a first group of apertures in a liner with an immobile gel; positioning the liner within the well bore thereby defining a first annulus between the liner and the well bore; transporting a slurry comprised of gravel suspended in a fluid into the first annulus, the fluid flowing through a second group of apertures in the liner while the gravel is deposited within the first annulus to form a gravel pack; and thereafter removing substantially all of the gel from the first group of apertures.

  12. The Relation between the Fear-Avoidance Model and Constructs from the Social Cognitive Theory in Acute WAD.

    PubMed

    Sandborgh, Maria; Johansson, Ann-Christin; Söderlund, Anne

    2016-01-01

    In the fear-avoidance (FA) model social cognitive constructs could add to explaining the disabling process in whiplash associated disorder (WAD). The aim was to exemplify the possible input from Social Cognitive Theory on the FA model. Specifically the role of functional self-efficacy and perceived responses from a spouse/intimate partner was studied. A cross-sectional and correlational design was used. Data from 64 patients with acute WAD were used. Measures were pain intensity measured with a numerical rating scale, the Pain Disability Index, support, punishing responses, solicitous responses, and distracting responses subscales from the Multidimensional Pain Inventory, the Catastrophizing subscale from the Coping Strategies Questionnaire, the Tampa Scale of Kinesiophobia, and the Self-Efficacy Scale. Bivariate correlational, simple linear regression, and multiple regression analyses were used. In the statistical prediction models high pain intensity indicated high punishing responses, which indicated high catastrophizing. High catastrophizing indicated high fear of movement, which indicated low self-efficacy. Low self-efficacy indicated high disability, which indicated high pain intensity. All independent variables together explained 66.4% of the variance in pain disability, p < 0.001. Results suggest a possible link between one aspect of the social environment, perceived punishing responses from a spouse/intimate partner, pain intensity, and catastrophizing. Further, results support a mediating role of self-efficacy between fear of movement and disability in WAD.

  13. The Relation between the Fear-Avoidance Model and Constructs from the Social Cognitive Theory in Acute WAD

    PubMed Central

    Johansson, Ann-Christin

    2016-01-01

    In the fear-avoidance (FA) model social cognitive constructs could add to explaining the disabling process in whiplash associated disorder (WAD). The aim was to exemplify the possible input from Social Cognitive Theory on the FA model. Specifically the role of functional self-efficacy and perceived responses from a spouse/intimate partner was studied. A cross-sectional and correlational design was used. Data from 64 patients with acute WAD were used. Measures were pain intensity measured with a numerical rating scale, the Pain Disability Index, support, punishing responses, solicitous responses, and distracting responses subscales from the Multidimensional Pain Inventory, the Catastrophizing subscale from the Coping Strategies Questionnaire, the Tampa Scale of Kinesiophobia, and the Self-Efficacy Scale. Bivariate correlational, simple linear regression, and multiple regression analyses were used. In the statistical prediction models high pain intensity indicated high punishing responses, which indicated high catastrophizing. High catastrophizing indicated high fear of movement, which indicated low self-efficacy. Low self-efficacy indicated high disability, which indicated high pain intensity. All independent variables together explained 66.4% of the variance in pain disability, p < 0.001. Results suggest a possible link between one aspect of the social environment, perceived punishing responses from a spouse/intimate partner, pain intensity, and catastrophizing. Further, results support a mediating role of self-efficacy between fear of movement and disability in WAD. PMID:27999473

  14. Awareness and practice of patients' rights among hospitalized patients at Wad-Medani Teaching Hospital, Sudan.

    PubMed

    Younis, Abobaker A H; Hassan, Amal H A; Dmyatti, Eylaph M E H; Elmubarak, Mehad A H; Alterife, Rahma A A; Salim, Rawan E O; Mohamed, Samar A B; Ahmed, Wefag S A M

    2017-03-30

    Patients' rights are a fundamental human right and an important part of modern health care practice. This is a cross-sectional descriptive analytic study, conducted amongst 263 patients at Wadi-Medani Teaching Hospital, Sudan, in March-April 2015. Most patients (95.2%) did not know about the Bill of Rights and most of them (92.8%) were not able to mention any of the patients' rights. The most practiced rights were: the right to be asked for permission before examination (88.1%), proper handling (87.8%), safety of the hospital (87%), presence of a third person when examining a female by a male doctor (85.6%), and admission file confidentiality (75.5%). The awareness of Sudan FMOH Patients' Bill of Rights was very low among patients at Wad-Medani Teaching Hospital, yet they showed a high satisfaction rate probably due to their low socioeconomic status, educational level and expectations. Therefore, awareness of patients' rights must be increased.

  15. Facile decolorization of methylene blue with flower-like manganese wads.

    PubMed

    Yang, Aili; Huang, Chinpao; Wei, Bingqing; Zhang, Zhengjun

    2014-01-01

    Flower-like manganese wads (MWs) were synthesized via a simple and inexpensive ultrasonic irradiation method for the first time. MWs were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray and transmission electronic microscopy. The decolorization efficiency of MWs for methylene blue (MB) azo dye was examined as a function of pH, stirring time, MW dosage and initial concentration of the MB solution. Results show that MWs have excellent decolorization performance for MB with a higher efficiency (and without using H2O2 or other devises such as UV light and ultrasonic irradiation) compared to other catalysts, such as the mixture of Mn3O4 and H2O2 (with a maximum decolorization rate of 99.7% in 3 h), ZnS and CdS under light irradiation (with a maximum decolorization rate of 73% in 6 h), and sulfate modified titania under solar radiation (with a maximum decolorization rate of nearly 100% in 4 h).

  16. Sand transport over an immobile gravel substrate

    USDA-ARS?s Scientific Manuscript database

    Experiments were conducted in a laboratory flume channel to evaluate the effects of increasing amounts of sand with an immobile gravel fraction on the sand transport rate and configuration of the sand bed. Knowledge of the movement of sand in gravel beds is important for the management of streams a...

  17. MRI study of the cross-sectional area for the cervical extensor musculature in patients with persistent whiplash associated disorders (WAD).

    PubMed

    Elliott, James; Jull, Gwendolen; Noteboom, Jon Timothy; Galloway, Graham

    2008-06-01

    Cervical muscle function is disturbed in patients with persistent pain related to a whiplash associated disorder (WAD) but little is known about neck extensor muscle morphometry in this group. This study used magnetic resonance imaging to measure relative cross-sectional area (rCSA) of the rectus capitis posterior minor and major, multifidus, semispinalis cervicis and capitis, splenius capitis and upper trapezius muscles bilaterally at each cervical segment. In total, 113 female subjects (79 WAD, 34 healthy control; 18-45 years, 3 months-3 years post-injury) were recruited for the study. Significant main effects for differences in muscle and segmental level were found between the two groups (P < 0.0001) as well as a significant group * muscle * level interaction (P < 0.0001). The cervical multifidus muscle in the WAD group had significantly larger rCSA at all spinal levels and in contrast, there were variable differences in rCSA measures across levels in the intermediate and superficial extensor muscles when compared to the healthy controls (P < 0.0001). There were occasional weak, although statistically significant relationships between age, body mass index (BMI), duration of symptoms and the size of some muscles in both healthy control and WAD subjects (P < 0.01). It is possible that the consistent pattern of larger rCSA in multifidus at all levels and the variable pattern of rCSA values in the intermediate and superficial muscles in patients with WAD may reflect morphometric change due to fatty infiltrate in the WAD muscles. Future clinical studies are required to investigate the relationships between muscular morphometry, symptoms and function in patients with persistent WAD.

  18. Diffusion coefficients in gravel under unsaturated conditions

    SciTech Connect

    Conca, J.L.; Wright, J. )

    1990-05-01

    Diffusion coefficients were experimentally determined in unsaturated gravel to evaluate the effectiveness of gravel as a diffusion barrier to ionic transport in the vadose zone. Water contents were fixed by use of an ultracentrifuge with an ultralow constant rate flow pump supplying solution to the sample via a rotating seal. Once the gravel was at hydraulic steady state, the electrical conductivity was measured, and the diffusion coefficient calculated using the Nernst-Einstein equation. Diffusion coefficient values for potassium ion (D{sub e}) in four types of angular gravel ranged from 1.7 {times} 10{sup {minus}11} m{sup 2}/s (1.7 {times} 10{sup {minus}7} cm{sup 2}/s) for a 6.3-9.5 mm angular granitic gravel at a volumetric water content of 5.5% to 2.2 {times} 10{sup {minus}14} m{sup 2}/s (2.2 {times} 10{sup {minus}10} cm{sup 2}/s) in a 4.0-6.3 mm quartzite gravel at a volumetric water content of 0.47%. Variations in D{sub e} values resulted primarily from differences in water content which depends on gravel type and particle size.

  19. Optimizing materials for better gravel packs

    SciTech Connect

    Cocales, B. )

    1992-12-01

    This paper reports on the permeability of crystalline silica (commercial) gravel used for gravel packs. Many gravel properties are tested and monitored frequently, but an industry permeability standard has not been established. To standardize permeability numbers, experiments were conducted on crystalline silica and aluminum silicate (Carbo-Prop) using a constant-head permeameter. Equations developed from lab results show permeability as a function of porosity. These equations were developed for each material size and type, and can be used to determine permeability for any porosity.

  20. The identification of wadB, a new glycosyltransferase gene, confirms the branched structure and the role in virulence of the lipopolysaccharide core of Brucella abortus.

    PubMed

    Gil-Ramírez, Yolanda; Conde-Álvarez, Raquel; Palacios-Chaves, Leyre; Zúñiga-Ripa, Amaia; Grilló, María-Jesús; Arce-Gorvel, Vilma; Hanniffy, Sean; Moriyón, Ignacio; Iriarte, Maite

    2014-08-01

    Brucellosis is a worldwide extended zoonosis caused by Brucella spp. These gram-negative bacteria are not readily detected by innate immunity, a virulence-related property largely linked to their surface lipopolysaccharide (LPS). The role of the LPS lipid A and O-polysaccharide in virulence is well known. Moreover, mutation of the glycosyltransferase gene wadC of Brucella abortus, although not affecting O-polysaccharide assembly onto the lipid-A core section causes a core oligosaccharide defect that increases recognition by innate immunity. Here, we report on a second gene (wadB) encoding a LPS core glycosyltransferase not involved in the assembly of the O-polysaccharide-linked core section. As compared to wild-type B. abortus, a wadB mutant was sensitive to bactericidal peptides and non-immune serum, and was attenuated in mice and dendritic cells. These observations show that as WadC, WadB is also involved in the assembly of a branch of Brucella LPS core and support the concept that this LPS section is a virulence-related structure.

  1. Radiocarbon dating of the Early Natufian at el-Wad Terrace, Mount Carmel, Israel

    NASA Astrophysics Data System (ADS)

    Eckmeier, E.; Yeshurun, R.; Weinstein-Evron, M.; Mintz, E.; Boaretto, E.

    2012-04-01

    The Natufian culture (15-11.5 kyr BP) of the Levant played an integral role in the transition from nomadic hunter-gatherers to the establishment of sedentism and, finally, to food producing societies of the Neolithic. The Natufian sites in the Southern Levant are characterised by a lack of macrobotanical remains, including charcoal, and a poor preservation of bone collagen. A result of the scarcity of radiocarbon dateable material is that only about 30 reliable radiocarbon dates from the Natufian are available for constructing a chronology of this period, which would enable a better synchronisation of archaeological and environmental data. A key question of Natufian research is if and to what extent past climate changes influenced the lifestyle of the Natufian communities, but the prerequisite for the correlation of cultural and environmental events in time are accurate chronologies. Therefore, a chronological framework with dates from well-defined contexts and samples of good quality is essential for the investigation of the Natufian. We present new C-14 data from the site of el-Wad Terrace, one of the major Natufian hamlets of the 'core area' of this culture. The samples (12 charcoals and 34 bones, of which 6 charcoals and 5 bones were suitable for dating) were derived from Early Natufian (15-13 kyr BP) living surfaces, dwellings and burials. Using FTIR, we investigated the environmental factors that influenced the preservation of material for radiocarbon dating of the site, and we tested a modified pre-treatment method for poorly preserved charcoal samples. We found that the usual pre-treatment protocol for C-14 samples (W-ABA) removed more charcoal material than the method modified by Rebollo et al. (2008) which omits the first acid treatment (W-BA). This first acid step enhanced the extraction of humic substances during the subsequent base step. The modified W-BA method is a promising tool for dating poorly preserved charcoals which needs further testing with

  2. Crossfire-Bonds Gravel Pit NPDES Permit

    EPA Pesticide Factsheets

    This is an NPDES permit and statement of basis. The Crossfire-Bonds Gravel Pit is authorized to discharge to Deer Canyon. Authorization for discharge is limited to only those outfalls specifically listed in the permit.

  3. Modeling surficial sand and gravel deposits

    USGS Publications Warehouse

    Bliss, J.D.; Page, N.J.

    1994-01-01

    Mineral-deposit models are an integral part of quantitative mineral-resource assessment. As the focus of mineral-deposit modeling has moved from metals to industrial minerals, procedure has been modified and may be sufficient to model surficial sand and gravel deposits. Sand and gravel models are needed to assess resource-supply analyses for planning future development and renewal of infrastructure. Successful modeling of sand and gravel deposits must address (1) deposit volumes and geometries, (2) sizes of fragments within the deposits, (3) physical characteristics of the material, and (4) chemical composition and chemical reactivity of the material. Several models of sand and gravel volumes and geometries have been prepared and suggest the following: Sand and gravel deposits in alluvial fans have a median volume of 35 million m3. Deposits in all other geologic settings have a median volume of 5.4 million m3, a median area of 120 ha, and a median thickness of 4 m. The area of a sand and gravel deposit can be predicted from volume using a regression model (log [area (ha)] =1.47+0.79 log [volume (million m3)]). In similar fashion, the volume of a sand and gravel deposit can be predicted from area using the regression (log [volume (million m3)]=-1.45+1.07 log [area (ha)]). Classifying deposits by fragment size can be done using models of the percentage of sand, gravel, and silt within deposits. A classification scheme based on fragment size is sufficiently general to be applied anywhere. ?? 1994 Oxford University Press.

  4. Modelling gravel transport and morphology for the Fraser River Gravel Reach, British Columbia

    NASA Astrophysics Data System (ADS)

    Li, S. S.; Millar, R. G.; Islam, S.

    2008-03-01

    A two-dimensional (2D) numerical hydrodynamic-morphological model is developed to investigate gravel transport and channel morphology in a large wandering gravel-bed river, the Fraser River Gravel Reach, in British Columbia, Canada. The model takes into count multi-fraction bedload transport, including the effects of surface coarsening, hiding and protrusion. Model outputs together with river discharge statistics were analyzed, producing distributed sediment budget and well-defined, localised zones of aggradation and degradation along the gravel reach. Long-term channel response to gravel extraction from aggrading zones as a flood hazard mitigation measure was also investigated numerically to assess the effectiveness of such an extraction. The total computed sediment budget agrees well with results based on field measurements of gravel transport available to us. This study points to the importance of a number of factors to bedload predictions: the gravel-to-sand ratio, the adequacy of resolving the wandering planform, and the distinction between bed shear stress driving bedload transport and bed resistance on the flow. These are in addition to the physical processes governing the flow field and gravel mobilization. The methodology presented in this paper can provide a scientific basis for gravel management including monitoring and extraction in order to maintain adequate flood protection and navigation, while preserving the ecosystem.

  5. Protection of gravel pack well completions during steam injection

    SciTech Connect

    Burrows, D.N.; Northrop, P.S.

    1993-08-31

    A method is described for protecting a gravel pack completion in a well through which steam is injected into a subterranean formation wherein gravel used to form said gravel pack completion contains silica; said method comprising: passing said steam through a silica-containing particulate material at the surface prior to injecting said steam through said gravel pack well completion.

  6. MICROTURBULENCE IN GRAVEL BED STREAMS

    NASA Astrophysics Data System (ADS)

    Papanicolaou, T.; Tsakiris, A. G.; Kramer, C. M.

    2009-12-01

    The overarching objective of this investigation was to evaluate the role of relative submergence on the formation and evolution of cluster microforms in gravel bed streams and its implications to bedload transport. Secondary objectives of this research included (1) a detailed analysis of mean flow measurements around a clast; and (2) a selected number of experimental runs where the mean flow characteristics are linked together with the bed micro-topography observations around a clast. It is hypothesized that the relative submergence is an important parameter in defining the feedback processes between the flow and clasts, which governs the flow patterns around the clasts, thus directly affecting the depositional patterns of the incoming sediments. To examine the validity of the hypothesis and meet the objectives of this research, 19 detailed experimental runs were conducted in a tilting, water recirculating laboratory flume under well-controlled conditions. A fixed array of clast-obstacles were placed atop a well-packed bed with uniform size glass beads. During the runs, multifractional spherical particles were fed upstream of the clast section at a predetermined rate. State-of-the-art techniques/instruments, such as imaging analysis software, Large Scale Particle Velocimeter (LSPIV) and an Acoustic Doppler Velocimetry (ADV) were employed to provide unique quantitative measurements for bedload fluxes, clast/clusters geomorphic patterns, and mean flow characteristics in the vicinity of the clusters. Different flow patterns were recorded for the high relative submergence (HRS) and low relative submergence (LRS) experimental runs. The ADV measurements provided improved insight about the governing flow mechanisms for the HRS runs. These mechanisms were described with flow upwelling at the center of the flume and downwelling occurring along the flume walls. Flow downwelling corresponded to an increase in the free surface velocity. Additionally, the visual observations

  7. Roughness of stable, armored gravel beds

    NASA Astrophysics Data System (ADS)

    Gomez, Basil

    1993-11-01

    The grain roughness of stable armored beds that formed in a laboratory flume under a range of steady flow conditions on rounded, flat and angular gravel is analyzed. Gravel roughness geometry is determined from bed surface profiles and vertical photographs. These techniques have been employed in field situations. Thus the methodology is potentially applicable to the analysis of grain roughness in natural gravel bed channels. The description of representative roughness geometry is also analogous to that used to characterize artificial roughness arrays. Armor roughness increases with increasing flow. Armored surfaces composed of angular gravel are roughest, and surfaces formed of flat gravel offer least resistance to the flow. Stable armored beds may exhibit a tendency to maximize the ratio of the shear due to drag on representative roughness elements to total shear. Roughness concentration is strongly correlated with the energy slope, and there is a linear increase in equivalent roughness height with increasing roughness concentration. The friction factor for an armored surface varies in a linear manner with representative roughness geometry. The equation defining this relation is probably similar to that used to characterize variations in the friction factor with artificial roughness geometry at low roughness concentrations. However, to reconcile the relations for artificial and natural roughness completely, it may be necessary to explicitly consider the contribution to flow resistance made by roughness shape, background roughness, and blocking in shallow flows.

  8. Laboratory studies of fines movement in gravel packs

    SciTech Connect

    Jennings, A.R. Jr.

    1996-12-31

    Most high permeability, high deliverability, unconsolidated and loosely consolidated sandstone formations require gravel packing as part of the completion procedure. The gravel packs are designed to allow the soft formations to produce sand-free at economic production rates. Techniques and procedures used for gravel size selection are typically based on criteria which have been used by the industry for over 20 years. Simple laboratory flow tests using clean gravel columns and fines from a variety of formations, however, indicate existing gravel-size selection guidelines are too conservative. Although the gravels selected are very efficient in preventing formation fines from entering the pack, the buildup of silt and fines at the gravel/formation interface can cause quick degradation of the effective permeability through the pack. Improvements in gravel pack life can be obtained by using gravel with higher initial permeability, either by increasing the average size of the gravels used (i.e. larger sand grains) or through the use of more spherical particles (synthetic gravel). The laboratory tests reported in this paper suggest that both alternatives can be considered in gravel pack operations. It is a further premise of this paper that sufficient improvements have been made in gravel pack procedures in recent years to allow effective placement of the higher permeability gravels proposed.

  9. Laboratory studies of fines movement in gravel packs

    SciTech Connect

    Jennings, A.R. Jr.

    1997-12-01

    Most high-permeability, high-deliverability, unconsolidated, and loosely consolidated sandstone formations require gravel packing as part of the completion procedure. The gravel packs are designed to allow the soft formations to produce sand-free at economical production rates. Techniques and procedures used for gravel-size selection are typically based on criteria that have been used by the industry for more than 20 years. Simple laboratory flow tests using clean gravel columns and fines from a variety of formations, however, indicate that existing gravel-size-selection guidelines are too conservative. Although the gravels selected are very efficient in preventing formation fines from entering the pack, the buildup of silt and fines at the gravel/formation interface can cause quick degradation of the effective permeability through the pack. Improvements in gravel-pack life can be obtained by using gravel with higher initial permeability, either by increasing the average size of the gravels used (i.e., larger sand grains) or through the use of more spherical particles (synthetic gravel). The laboratory tests reported in this paper suggest that both alternatives can be considered in gravel-pack operations. It is a further premise of this paper that sufficient improvements have been made in gravel-pack procedures in recent years to allow effective placement of the proposed higher-permeability gravels.

  10. Sand, gravel properties key to optimum designs

    SciTech Connect

    Oyeneyin, M.B.

    1998-01-26

    Successful gravel packed and screen well completions require a knowledge of sand as well as gravel textural properties. These completion methods keep sand and fines from entering the well bore, so that long-term production capacity of the well is ensured. This first of a three-part series will cover key factors that influence effective sand control. The concluding parts will present guidelines for both gravel packs and screens. Fines, more than load-bearing formation sands, pose the greater problem for the two sand exclusion techniques. Therefore, reservoir sand analysis is the main key for controlling sand. An integrated team approach to both sand control design and implementation from well planning through drilling to final completion is the best strategy for optimizing well performance in reservoirs with sand problems.

  11. Gravel Augmentation Below Dams: California Experiences

    NASA Astrophysics Data System (ADS)

    Kondolf, G. M.; Minear, J. T.

    2004-12-01

    Most dams block all coarse sediment traveling downstream, such that reaches downstream are commonly typically depleted of gravel, causing a variety of effects such as incision, bank erosion, coarsening of the bed material, and reduction of salmonid spawning habitiat. To compensate for this reduction in coarse sediment supply, gravel has been artificially added below dams, using techniques such as high flow stock piling, high flow direct injection, artificial riffle construction, riffle supplementation, and construction of side channel or artificial spawning channels. In the Trinity and Sacramento-San Joaquin River systems of northern California, loss of suitable salmonid spawning gravels below dams has motivated augmentation of over 320,000 m3 of gravel in 73 separate projects on 19 rivers since 1978, mostly since 1990. Of the 67 projects for which adequate data were available, 48 involved adding less than 7,500 m3 each. Costs reported for 57 of the projects totaled nearly $8,753,000, but these figures generally did not include the cost of staff time involved in planning, design, and oversight. Despite the magnitude of this experimental intervention, fewer than half of the projects were monitored, and of those few had monitored sufficient parameters pre- and post- project to evaluate project performance. Performance of these projects to date has been mixed: in many cases the imported gravels have promptly washed out, some channel forms created have been unnatural and not heavily used by salmon. In all cases, the volumes of gravel artificially added have been only a small percentage of the annual coarse sediment deficit.

  12. Where does all the gravel go? Abrasion-set limits on Himalayan gravel flux

    NASA Astrophysics Data System (ADS)

    Dingle, Elizabeth; Attal, Mikael; Sinclair, Hugh

    2017-04-01

    Rivers sourced in the Himalaya carry some of the largest sediment loads on the planet, yet coarse gravel in these rivers vanishes within approximately 20-40 kilometres on entering the Ganga Plain. Understanding "where the gravel goes" is crucial to forecasting the response of rivers to large pulses of sediment triggered by earthquakes and storms. Through an analysis of fan geometry, sediment grain size and lithology, we demonstrate that gravel flux from rivers draining the central Himalaya with contributing areas spanning three orders of magnitude is approximately constant. Furthermore, we show that the distance to the gravel-sand transition is independent of total sediment flux and water discharge, where subsidence rates are comparable. Findings from our lithology-dependent abrasion model reveal that abrasion of gravel during fluvial transport can explain this observation; most of the gravel sourced from more than 100 km upstream is converted into sand by the time it reaches the Plain. Our results also suggest that over the length scale of large trans-Himalayan rivers, abrasion facilitates the downstream translation and dispersion of earthquake generated sediment. Increased sediment delivery to channels (e.g. following large earthquakes or storms) will only result in an additional pulse of gravel reaching the Plain if sediment delivery occurs within less than 100 km upstream of the mountain front or is sourced in highly resistant lithologies.

  13. A survey of physical therapists’ clinical practice patterns and adherence to clinical guidelines in the management of patients with whiplash associated disorders (WAD)

    PubMed Central

    Corkery, Marie B; Edgar, Kristen L; Smith, Christine E

    2014-01-01

    Objectives To explore the clinical practice of physical therapists and examine adherence to clinical guidelines for treating patients with whiplash associated disorders (WAD). Methods A cross-sectional electronic survey was sent to 1484 licensed physical therapists from the Orthopedic Section of the American Physical Therapy Association and the American Academy of Orthopedic Manual Physical Therapists. The survey included demographic data and two clinical vignettes describing patients with acute and chronic WAD. The chi-square test was used to analyze responses. Results There were 291(19.6%) responses to the survey. Of those, 237 (81.4%) provided data for vignette 1 and 204 (70.1%) for vignette 2. One hundred and eighty (76.6%) respondents reported familiarity with evidence-based or clinical practice guidelines for treating patients with WAD. Of those, 71.5% (n = 128) indicated that they followed them more than 50% of the time. Therapists with an advanced certification were more likely to be familiar with clinical guidelines than those who were not certified (P<0.01). Responses indicated overall adherence to guidelines; however, there was a low utilization of quantitative sensory assessment, screening for psychological distress and some outcome measures. Significant differences in clinical practice (P<0.01) were found between therapists who were and were not familiar with guidelines and those with and without an advanced certification. Discussion Advanced certification and knowledge of guidelines appeared to play a role in the clinical practice of physical therapists treating patients with WAD. Further research is needed to explore factors affecting knowledge translation from research to clinical practice and to evaluate the outcomes of patients with WAD when clinical guidelines are applied in practice. PMID:24976750

  14. A survey of physical therapists' clinical practice patterns and adherence to clinical guidelines in the management of patients with whiplash associated disorders (WAD).

    PubMed

    Corkery, Marie B; Edgar, Kristen L; Smith, Christine E

    2014-05-01

    To explore the clinical practice of physical therapists and examine adherence to clinical guidelines for treating patients with whiplash associated disorders (WAD). A cross-sectional electronic survey was sent to 1484 licensed physical therapists from the Orthopedic Section of the American Physical Therapy Association and the American Academy of Orthopedic Manual Physical Therapists. The survey included demographic data and two clinical vignettes describing patients with acute and chronic WAD. The chi-square test was used to analyze responses. There were 291(19.6%) responses to the survey. Of those, 237 (81.4%) provided data for vignette 1 and 204 (70.1%) for vignette 2. One hundred and eighty (76.6%) respondents reported familiarity with evidence-based or clinical practice guidelines for treating patients with WAD. Of those, 71.5% (n = 128) indicated that they followed them more than 50% of the time. Therapists with an advanced certification were more likely to be familiar with clinical guidelines than those who were not certified (P<0.01). Responses indicated overall adherence to guidelines; however, there was a low utilization of quantitative sensory assessment, screening for psychological distress and some outcome measures. Significant differences in clinical practice (P<0.01) were found between therapists who were and were not familiar with guidelines and those with and without an advanced certification. Advanced certification and knowledge of guidelines appeared to play a role in the clinical practice of physical therapists treating patients with WAD. Further research is needed to explore factors affecting knowledge translation from research to clinical practice and to evaluate the outcomes of patients with WAD when clinical guidelines are applied in practice.

  15. Erosion of sand from a gravel bed

    USDA-ARS?s Scientific Manuscript database

    Cleaning of fine sediment out of gravel stream beds has become an important method to restore impacted stream habitats. Introducing the increased flows needed to entrain fine sediments without eroding the coarser fractions of the bed and potentially destroying its usefulness as a habitat requires c...

  16. Grain Exchange Probabilities Within a Gravel Bed

    NASA Astrophysics Data System (ADS)

    Haschenburger, J.

    2008-12-01

    Sediment transfers in gravel-bed rivers involve the vertical exchange of sediments during floods. These exchanges regulate the virtual velocity of sediment and bed material texture. This study describes general tendencies in the vertical exchange of gravels within the substrate that result from multiple floods. Empirical observations come from Carnation Creek, a small gravel-bed river with large woody debris located on the west coast of Vancouver Island, British Columbia. Frequent floods and the relatively limited armor layer facilitate streambed activity and relatively high bedload transport rates, typically under partial sediment transport conditions. Over 2000 magnetically tagged stones, ranging in size from 16 to 180 mm, were deployed on the bed surface between 1991 and 1992. These tracers have been recovered 10 times over 12 flood seasons to quantify their vertical position in the streambed. For analysis, the bed is divided into layers based on armor layer thickness. Once tracers are well mixed within the streambed, grains in the surface layer are most likely to be mixed into the subsurface, while subsurface grains are most likely to persist within the subsurface. Fractional exchange probabilities approach size independence when the most active depth of the substrate is considered. Overall these results highlight vertical mixing as an important process in the dispersion of gravels.

  17. Partial entrainment of gravel bars during floods

    USGS Publications Warehouse

    Konrad, C.P.; Booth, D.B.; Burges, S.J.; Montgomery, D.R.

    2002-01-01

    Spatial patterns of bed material entrainment by floods were documented at seven gravel bars using arrays of metal washers (bed tags) placed in the streambed. The observed patterns were used to test a general stochastic model that bed material entrainment is a spatially independent, random process where the probability of entrainment is uniform over a gravel bar and a function of the peak dimensionless shear stress ??*0 of the flood. The fraction of tags missing from a gravel bar during a flood, or partial entrainment, had an approximately normal distribution with respect to ??*0 with a mean value (50% of the tags entrained) of 0.085 and standard deviation of 0.022 (root-mean-square error of 0.09). Variation in partial entrainment for a given ??*0 demonstrated the effects of flow conditioning on bed strength, with lower values of partial entrainment after intermediate magnitude floods (0.065 < ??*0 < 0.08) than after higher magnitude floods. Although the probability of bed material entrainment was approximately uniform over a gravel bar during individual floods and independent from flood to flood, regions of preferential stability and instability emerged at some bars over the course of a wet season. Deviations from spatially uniform and independent bed material entrainment were most pronounced for reaches with varied flow and in consecutive floods with small to intermediate magnitudes.

  18. Characterizing unsaturated diffusion in porous tuff gravel

    SciTech Connect

    Hu, Qinhong; Kneafsey, Timothy J.; Roberts, Jeffery J.; Tomutsa, Liviu; Wang, Joseph, S.Y.

    2003-11-12

    Evaluation of solute diffusion in unsaturated porous gravel is very important for investigations of contaminant transport and remediation, risk assessment, and waste disposal (for example, the potential high-level nuclear waste repository at Yucca Mountain, Nevada). For a porous aggregate medium such as granular tuff, the total water content is comprised of surface water and interior water. The surface water component (water film around grains and pendular water between the grain contacts) could serve as a predominant diffusion pathway. To investigate the extent to which surface water films and contact points affect solute diffusion in unsaturated gravel, we examined the configuration of water using x-ray computed tomography in partially saturated gravel, and made quantitative measurements of diffusion at multiple water contents using two different techniques. In the first, diffusion coefficients of potassium chloride in 2-4 mm granular tuff at multiple water contents were calculated from electrical conductivity measurements using the Nernst-Einstein equation. In the second, we used laser ablation with inductively coupled plasma-mass spectrometry to perform micro-scale mapping, allowing the measurement of diffusion coefficients for a mixture of chemical tracers for tuff cubes and tetrahedrons having two contact geometries (cube-cube and cube-tetrahedron). The x-ray computed tomography images show limited contact between grains, and this could hinder the pathways for diffusive transport. Experimental results show the critical role of surface water in controlling transport pathways and hence the magnitude of diffusion. Even with a bulk volumetric water content of 1.5%, the measured solute diffusion coefficient is as low as 1.5 x 10{sup -14} m{sup 2}/s for tuff gravel. Currently used diffusion models relating diffusion coefficients to total volumetric water content inadequately describe unsaturated diffusion behavior in porous gravel at very low water contents.

  19. Fine bed material in pools of natural gravel bed channels

    Treesearch

    Thomas E. Lisle; Sue Hilton

    1999-01-01

    Abstract - Natural gravel bed channels commonly contain a fine mode of sand and fine gravel that fills voids of the bed framework of coarser gravel. If the supply of fine bed material exceeds the storage capacity of framework voids, excess fine material forms surficial patches, which can be voluminous in pools during low flow. Data collected in 34 natural channels in...

  20. Expandable mixing section gravel and cobble eductor

    DOEpatents

    Miller, Arthur L.; Krawza, Kenneth I.

    1997-01-01

    In a hydraulically powered pump for excavating and transporting slurries in hich it is immersed, the improvement of a gravel and cobble eductor including an expandable mixing section, comprising: a primary flow conduit that terminates in a nozzle that creates a water jet internal to a tubular mixing section of the pump when water pressure is applied from a primary supply flow; a tubular mixing section having a center line in alignment with the nozzle that creates a water jet; a mixing section/exit diffuser column that envelopes the flexible liner; and a secondary inlet conduit that forms an opening at a bas portion of the column and adjacent to the nozzle and water jet to receive water saturated gravel as a secondary flow that mixes with the primary flow inside of the mixing section to form a combined total flow that exits the mixing section and decelerates in the exit diffuser.

  1. Mineral scale in gravel packed wells

    SciTech Connect

    Schmidt, T.; Soereide, F.

    1994-12-31

    Mineral scales of barium, strontium and calcium sulphate are well known to the oil industry. The most common scale is calcium carbonate. However carbonate, unlike the three other scales mentioned, is acid soluble and it is perhaps the sulphate scales which gives the greatest problems. One additional feature of the sulphate scales is that they very often coprecipitate radium sulphate which is radioactive and difficult to dispose of and troublesome to work with from a health and safety aspect. This paper presents the production history of gravel packed wells which have experienced the deposition and removal of mainly strontium sulphate (SrSO{sub 4}) scale. A scale prediction program is used to analyze the scale tendencies under both equilibrium and kinetic controlled conditions. The flow and scale characteristics of gravel packed and naturally completed wells are compared.

  2. Effect of gravel on hydraulic conductivity of compacted soil liners

    SciTech Connect

    Shelley, T.L. ); Daniel, D.E. )

    1993-01-01

    How much gravel should be allowed in low-hydraulic-conductivity, compacted soil liners To address this question, two clayey soils are uniformly mixed with varying percentages of gravel that, by itself, has a hydraulic conductivity of 170 cm/s. Soil/gravel mixtures are compacted and then permeated. Hydraulic conductivity of the compacted gravel/soil mixtures is less than 1 [times] 10[sup [minus]7] cm/s for gravel contents as high as 50-60%. For gravel contents [le] 60%, gravel content is not important: all test specimens have a low hydraulic conductivity. For gravel contents > 50-60%, the clayey soils does not fill voids between gravel particles, and high hydraulic conductivity results. The water content of the nongravel fraction is found to be a useful indicator of proper moisture conditions during compaction. From these experiments in which molding water content and compactive energy are carefully controlled, and gravel is uniformly mixed with the soil, it is concluded that the maximum allowable gravel content is approximately 50%.

  3. Characterizing Unsaturated Diffusion in Porous Tuff Gravel

    SciTech Connect

    Hu, Q; Kneafsey, T J; Roberts, J J; Tomutsa, L; Wang, J S

    2003-11-12

    Evaluation of solute diffusion in unsaturated porous gravel is very important for investigations of contaminant transport and remediation, risk assessment, and waste disposal (e.g., the potential high-level nuclear waste repository at Yucca Mountain, Nevada). For a porous aggregate medium such as granular tuff, the total water content is comprised of surface water and interior water. The surface water component (water film around grains and pendular water between the grain contacts) could serve as a predominant diffusion pathway. To investigate the extent of surface water films and contact points affect solute diffusion in unsaturated gravel, we examined the configuration of water using x-ray computed tomography in partially saturated gravel, and made quantitative measurements of diffusion at multiple water contents using two different techniques. In the first, diffusion coefficients of potassium chloride in 2-4 mm granular tuff at multiple water contents are calculated from electrical conductivity measurements using the Nernst-Einstein equation. In the second, we used laser ablation with inductively coupled plasma-mass spectrometry to perform micro-scale mapping, allowing the measurement of diffusion coefficients for a mixture of chemical tracers for tuff cubes and tetrahedrons having two contact geometries (cube-cube and cube-tetrahedron). The x-ray computed tomography images show limited contact between grains, and this could significantly hinder the pathways for diffusive transport. Experimental results show the critical role of surface water in controlling transport pathways and hence the magnitude of diffusion. Even with a bulk volumetric water content of 1.5%, the measured solute diffusion coefficient is as low as 1.5 x 10{sup -14} m{sup 2}/s. Currently used diffusion models relating diffusion coefficients to total volumetric water content inadequately describe unsaturated diffusion behavior in porous gravel.

  4. Method for reducing water production from a gravel packed well

    SciTech Connect

    Summers, L.E.

    1992-02-25

    This patent describes a process for reducing water production from a well having a gravel containing gravel pack traversing a production zone, the gravel pack including a perforated tubing extending through the gravel pack, a screen over a perforate section of the tubing; isolating packers above and below the screen, and gravel packing between the screen and perforated casing adjacent- the production zone, the production zone including a lower water-producing interval and an upper hydrocarbon-producing interval. It comprises: placing a bridge plug within the perforate tubing at a position below the hydrocarbon-producing zone; placing a layer of coarse sand on the bridge plug, the coarse sand having an average particle sized greater than the average particle size of the gravel forming the gravel pack; placing a layer of fine sand over the layer of coarse sand, the fine sand having an average particle size smaller than the average particle size of the gravel forming the gravel pack and filling the tubing to a level at or above the top of the water-producing interval; placing a settable liquid resin through the tubing onto the top of the layer of fine sand, whereby the resin flows outwardly from the tubing to form a layer of resin extending from the tubing through the gravel; and allowing the resin to set, thereby forming a barrier to flow of water from the water-producing zone into the tubing.

  5. Riverbank erosion induced by gravel bar accretion

    NASA Astrophysics Data System (ADS)

    Klösch, Mario; Habersack, Helmut

    2010-05-01

    Riverbank erosion is known to be strongly fluvially controlled and determination of shear stresses at the bank surface and at the bank toe is a crucial point in bank erosion modeling. In many modeling attempts hydraulics are simulated separately in a hydrodynamic-numerical model and the simulated shear stresses are further applied onto the bank surface in a bank erosion model. Hydrodynamics are usually simulated at a constant geometry. However, in some cases bed geometry may vary strongly during the event, changing the conditions for hydrodynamics along the bank. This research seeks to investigate the effect of gravel bar accretion during high discharges on final bank retreat. At a restored section of the Drava River bed widenings have been implemented to counter bed degradation. There, in an initiated side-arm, self-dynamic widening strongly affects bed development and long-term connectivity to the main channel. Understanding the riverbank erosion processes there would help to improve planning of future restoration measures. At one riverbank section in the side-arm large bank retreat was measured repeatedly after several flow events. This section is situated between two groins with a distance of 60 m, which act as lateral boundaries to the self-widening channel. In front of this bank section a gravel bar developed. During low flow condition most discharge of the side-arm flows beside the gravel bar along the bank, but shear stresses are too low for triggering bank erosion. For higher discharges results from a two-dimensional hydrodynamic-numerical model suggested shear stresses there to be generally low during the entire events. At some discharges the modeled flow velocities even showed to be recirculating along the bank. These results didn't explain the observed bank retreat. Based on the modeled shear stresses, bank erosion models would have greatly underestimated the bank retreat induced by the investigated events. Repeated surveys after events applying

  6. Subsurface Flow in Gravel River Bars

    NASA Astrophysics Data System (ADS)

    Bray, E. N.; Dunne, T.

    2014-12-01

    The geomorphic and hydraulic characteristics of gravel bars control the direction, magnitude and spatial patterns of infiltration and exfiltration between rivers and their immediate subsurface environments. Bed undulation, water-surface gradient, alluvial depth, and the spatial variation of hydraulic conductivity (both deterministic trends and stochastic variability) affect the hydrologically-driven groundwater-surface water exchange. In this paper, we use a set of field measurements of morphological and hydrological characteristics along two reaches of the San Joaquin River, California to motivate a systematic analysis of the factors that affect paths and residence times of flow through gravel bars under an observed range of streamflow values. In the field investigation, it is shown that asymmetry of bar morphology is a first-order control on the extent and magnitude of infiltration, which is often represented to produce approximately equal areas of infiltration and seepage under the assumption of sinusoidal bedforms. Infiltration over the length of a bar is shown to be greater at low flow than at high flow because of the effect of water-surface gradient. Hydraulic conductivity (ksat) varies by orders of magnitude and systematic downstream coarsening arises related to the process of bar evolution. The lowest values of ksat were observed where the difference between the topographic gradient and the water-surface gradient is at a maximum and thus where the infiltration would be greatest into a uniform bar of homogeneous gravel. Morphology and fine sediment accumulation in recharge zones exert an important control over the mechanisms driving subsurface fluid exchange. Simulations from a numerical groundwater flow model that isolate the signatures of morphology and streambed sediment patterns on subsurface flow corroborate our interpretation that the infiltration patterns and rates are primarily controlled by bed morphology, with ksat playing a secondary role.

  7. Dual openhole gravel pack in shaly fine sands

    SciTech Connect

    Moricca, G.; Ripa, G.; Rucci, D.; Pitoni, E.

    1995-12-01

    This paper discusses the design and execution of dual-zone gravel packs in very shaly and silty formations of median sand grain size less than 30 {micro}m. An oversized gravel was selected for sand control and, as a consequence, the openhole gravel-pack technique was adopted to reduce the effect of intermixing between formation and gravel-pack sand. During the completions in the first five wells, the authors encountered and solved several operational problems, including those involving (1) borehole stability, (2) setting of inflatable packer for zone isolation, (3) hole preparation, and (4) gravel placement. From the lessons they learned, another 11 wells were completed with dual openhole gravel packs without significant problems. After 1 year of production, the flow performance from the wells met or exceeded the initial objectives.

  8. Erosion depth of sand from an immobile gravel bed

    NASA Astrophysics Data System (ADS)

    Kuhnle, R.; Wren, D.; Langendoen, E.

    2015-03-01

    This study was conducted to improve prediction of the depth of erosion of sand (D50 = 0.3-0.9 mm) from immobile gravel (D50 = 36.1 mm) under steady uniform flows with bed shear stresses from 0.1 to 0.9 of that required to entrain the gravel. This situation, often encountered downstream of dams, has important implications for habitat restoration. Steady uniform flows were imposed on a flume channel containing a mixture of sand and gravel until sediment concentrations in the flow exiting the channel became small. The elevation of sand relative to gravel was measured after each experiment and compared poorly to calculated depths from published relationships whose predictions were based in part on the equivalent grain roughness of the bed. An improved predictive relationship was developed by using the cumulative distribution function of the surface gravel elevations to scale the shear velocity available for transporting sand from the gravel substrate.

  9. Mineral resource of the month: industrial sand and gravel

    USGS Publications Warehouse

    Dolley, Thomas

    2007-01-01

    With many diverse uses, industrial sand and gravel, also known as silica sand, is one of the most important nonmetallic minerals in the world. Industrial sand and gravel is a mining industry term used for sands that have a very high percentage of silicon dioxide, or greater than 95 percent quartz. Deposits of industrial sand and gravel can be found virtually everywhere on Earth, but are less widespread than deposits of common construction sand and gravel. Industrial sand and gravel is distinctive in grain size, hardness, inertness and resistance to high temperature and chemical action. Beverage containers, fiberglass insulation, fiber-optic cables and light bulbs are just some of today’s many products produced from industrial sand and gravel.

  10. Effects of acids on gravels and proppants

    SciTech Connect

    Cheung, S.K.

    1988-05-01

    The effects of acids on the integrity of gravels and proppants should be considered in acid treatments. This paper reports on the influence of acid type, acid concentration, and contact duration on the acid solubility of five sands and bauxitic materials. The effects of the acids on the mechanical strength and the size distribution of the solids are determined. The authors found that intermediate-density and low-density bauxites (IDB and LDB) are very soluble in HF acid and that sintered bauxite is weakened by HF acid.

  11. Two-step method for horizontal gravel packing

    SciTech Connect

    Forrest, J.K.

    1991-10-22

    This patent describes a method for placing gravel within an annulus formed in a non-vertical borehole by the placement of a screen within the borehole. It comprises: injecting into the annulus a slurry of gravel and a medium viscosity carrier fluid to pack from 50% to 75% of the screen-borehole annulus; and injecting into the annulus a slurry of gravel and a low viscosity carrier fluid until the annulus is completely packed.

  12. Problems with Approximate Bearing Capacity of Gravel Soils

    NASA Astrophysics Data System (ADS)

    Plachý, Jan; Weiss, Viktorie; Bartuška, Ladislav

    2016-10-01

    The publication aims to bring undoubted importance approximate table bearing capacity of gravel soils, which are used in the new constructions. Tabulated values enable to determine the estimated bearing capacity of foundation soil for a simple and inexpensive construction to a depth of 1 meter. In the publication there are compares particular class of gravel soils in depending on the width of the base and ingredients of fine-grained soil. Gravelly soils are the best foundation soil in terms of bearing capacity, but the amount of fine-grained soils or poorly grained gravel, or gravel with a low value of relative density can greatly reduce this value.

  13. Quantifying the factors influencing gravel placement and productivity of an internally gravel packed completion based on field data analysis

    SciTech Connect

    Welling, R.W.F.; Jonathan, P.; Reijnen, P.H.F.; Samuel, A.J.

    1995-12-31

    A detailed analysis of 341 internally gravel-packed zones in wells from three oil fields was carried out to determine which parameters significantly influence the placement of the gravel in such a completion and the well`s resulting productivity. The database analysis demonstrates that, in addition to the well-known impairing factors, such as dirty completion fluids and viscous fluid-loss control pills, the performance of gravel packs can be improved by increasing the number of perforations--especially in 7 inch completions. This suggests that the perforation tunnel is the most critical area in an internally gravel-packed completion.

  14. Gravel pit lakes in Denmark: Chemical and biological state.

    PubMed

    Søndergaard, Martin; Lauridsen, Torben L; Johansson, Liselotte S; Jeppesen, Erik

    2017-08-25

    Mining of gravel and sand for construction purposes is big business and gravel pit lakes have become increasingly common all over the world. In Denmark, hundreds of gravel pit lakes have been created during the past decades. We investigated the chemical and biological status of 33-52 gravel pit lakes and compared the results with data from similar-sized natural Danish lakes. The area of the lakes ranged from 0.2 to 13ha and their age from 0.5 to 26years. Generally, the gravel pit lakes were clear with low nutrient concentrations, the median concentrations of total phosphorus and total nitrogen being 0.023mg/l and 0.30mg/l compared with 0.115mg/l and 1.29mg/l, respectively, in natural lakes. Correspondingly, median chlorophyll a was 5μg/l in the gravel pit lakes and 36μg/l in the natural lakes. Submerged macrophytes were found in all gravel pit lakes, with particularly high cover in the shallow ones. Most gravel pit lakes were deeper than the natural lakes, which may restrict the area potentially to be covered by submerged macrophytes, with implications also for the biological quality of the lakes. Fish were found in most of the gravel pit lakes, roach (Rutilus rutilus), perch (Perca fluviatilis) and rudd (Scardinius erythrophalmus) being the most frequently observed species. Fish stocking was common and included also non-native species such as carp (Cyprinus carpio) and rainbow trout (Oncorchynchus mykiss). Compared with the natural lakes, fish species richness and catch per gillnet were overall lower in the gravel pit lakes. Groundwater-fed gravel pit lakes add importantly to the number of high-quality lakes in Denmark and with an optimised design and by avoiding negative side effects, they can be positive for both nature and society. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Overwash threshold experiment for gravel barriers

    NASA Astrophysics Data System (ADS)

    Matias, Ana; Williams, Jon; Bradbury, Andrew; Masselink, Gerhard; Ferreira, Óscar

    2010-05-01

    Field measurements of overwash effects, associated physical forcing, and determination of threshold conditions, are much less common for gravel than for sandy barriers (e.g., field measurements by Lorang, 2002; Bradbury et al., 2005; and laboratory studies by Obhrai et al., 2008). In order to define overwash thresholds for gravel there is a need for measurements under a variety of forcing conditions that include waves, tides and surges. Flume experiments allow the manipulation of physical forcing and can make a valuable contribution to improve the understanding and prediction of overwash. To study gravel barrier overwash processes, BARDEX proto-type scale laboratory experiment was undertaken in the Delta flume (Williams et al., 2009). A 4 m high, 50 m wide gravel barrier composed of sediments with D50 = 10 mm was emplaced in the flume and subjected to a range of water levels, wave heights and wave periods. Barrier morphology was surveyed before and after each run. Two situations were simulated: overwashing and overtopping. Following Orford and Carter (1982) terminology, the distinction between overtopping and overwash was based on the type of morphological change over the barrier crest. Overtopping causes vertical accretion at the crest, whereas overwashing promotes the formation of washover deposits landwards from the crest. Ten overwash experiments were conducted (divided in 63 runs), and overtopping was recorded in 22 runs and overwash in 20 runs. In other runs, only the beach face was reworked by waves. In a systematic series of tests water levels were varied between 3.00 m and 3.75 m (in steps of 0.125 m); wave height was varied between 0.8 m and 1.3 m (in steps of 0.05 or 0.1 m); and wave periods of 4.5, 6, 7 and 8 seconds were used. These hydrodynamic conditions were used to compute wave run-up using several well-known formulae (cf., Powell, 1990; Stockdon et al., 2007). Comparison between run-up estimations and the barrier crest elevation prior to wave

  16. Experience in gravel packing long, perforated intervals in deviated holes

    SciTech Connect

    van Ballegooyen, J.; Giap, T.K.; Seng, T.K.

    1983-11-01

    This paper presents the philosophy, criteria, and technique used in arriving at the gravel-packing method for Sabah Shell Petroleum Co. Ltd.'s (SSPC's) operations. It also analyzes and discusses problems and efforts to resolve them with the aid of an evaluation tool. Intervals of up to 600 ft have been successfully gravel-packed by use of a highly viscous slurry technique with minor modifications. The CNL gives a qualitative indication of the gravel placement behind the liner. A reduction in either the gravel concentration or the volume of viscous pad ahead had no effect on reducing the incidence of bridging in the casing/WWS annulus. Large volumes of formation sand removed during perforation washing could not always be replaced with gravel. To ensure proper packoff, the wash volumes should be reduced. Stable gravel bridges will form against sand stringers of higher permeability in a 6 5/8-in./9 5/8-in. screen/casing annulus. Various parameters were changed to prevent this, but the only long-term solution appears to be the use of a smaller WWS. Gravel slumping does occur in hole angles up to 51/sup 0/ to fill voids created during placement. The importance of an adequate reservoir of gravel above the top perforation cannot be over emphasized.

  17. Erosion depth of sand from an immobile gravel bed

    USDA-ARS?s Scientific Manuscript database

    Abstract This study was conducted to provide information on the depth of erosion of sand (D50 = 0.3, 0.9 mm) from immobile gravel (D50 = 36.1 mm) under steady uniform flows with bed shear stresses from 0.1 to 0.9 of that required to entrain the gravel. This situation, often encountered downstream o...

  18. Use of succinoglycan biopolymer for gravel packing

    SciTech Connect

    Sanz, G.P.; Gunningham, M.C.; Samuel, A.J. . E P Lab.); Lau, H.C.

    1994-06-01

    This paper presents the results of laboratory experiments and field trials on a polysaccharide biopolymer, succinoglycan, for use in gravel packing. This biopolymer causes minimal formation damage and has unique rheological properties that combine high shear-thinning behavior with temperature-induced viscosity breakback; thus, it can be used without breakers. A scouting study has been carried out at KSEPL to identify new viscosifiers with better rheological properties that cause minimal formation damage. Ideally, breakers should not be required and on-site polymer preparation procedures should be simple enough to give reliable, repeatable performances. For slurry-pack-type operations, the polysaccharide biopolymer succinoglycan was identified as the best candidate. The biopolymer was developed for EOR during 1980--83 at the Sittingbourne Research Centre, Shell Research Ltd., U.K., and is marketed by Shell Intl. Chemical Co. Ltd. as Shellflo-S.''

  19. Mapping sand and gravel pits in the Patuxent River watershed

    NASA Technical Reports Server (NTRS)

    Schmidt, T. J.; Witt, R. G.

    1981-01-01

    LANDSAT data from July 1973 and June 1978 for the Patuxent River Watershed of Maryland were processed in an effort to devise an economical method of monitoring the reclamation of sand and gravel pits. ASTEP-II and IDIMS software were utilized to derive signatures for sand and gravel pits and other land use/land cover types. Both unsupervised and supervised classifications of the two data sets were produced. Resultant statistics and color output products were compared in order to determine the extent of reclamation and expansion of sand and gravel pits over the five-year time span and to check the locations of more recent sand and gravel pits. Preliminary results indicate that, for a selected northern sub-acre, signatures derived for sand and gravel pits were nearly 90 percent accurate.

  20. Mapping sand and gravel pits in the Patuxent River watershed

    NASA Technical Reports Server (NTRS)

    Schmidt, T. J.; Witt, R. G.

    1981-01-01

    LANDSAT data from July 1973 and June 1978 for the Patuxent River Watershed of Maryland were processed in an effort to devise an economical method of monitoring the reclamation of sand and gravel pits. ASTEP-II and IDIMS software were utilized to derive signatures for sand and gravel pits and other land use/land cover types. Both unsupervised and supervised classifications of the two data sets were produced. Resultant statistics and color output products were compared in order to determine the extent of reclamation and expansion of sand and gravel pits over the five-year time span and to check the locations of more recent sand and gravel pits. Preliminary results indicate that, for a selected northern sub-acre, signatures derived for sand and gravel pits were nearly 90 percent accurate.

  1. Mapping gravel bed river bathymetry from space

    NASA Astrophysics Data System (ADS)

    Legleiter, C. J.; Overstreet, B. T.

    2012-12-01

    Understanding river form and behavior requires an efficient means of measuring channel morphology. This study evaluated the potential to map the bathymetry of two clear-flowing, shallow (<3 m deep) gravel bed rivers <60 m wide from 2 m-pixel WorldView2 satellite images. Direct measurements of water column optical properties were used to quantify constraints on depth retrieval. The smallest detectable change in depth was 0.01-0.04 m and the maximum detectable depth was 5 m in green bands but <2 m in the near-infrared; lower sensor radiometric resolution yields less precise estimates over a smaller range. An algorithm for calibrating a band ratioX to field measurements of depth d proved effective when applied to spectra extracted from images (R2 = 0.822 and 0.594 for the larger and smaller stream, respectively) or measured in the field (R2 = 0.769 and 0.452). This procedure also identified optimal wavelength combinations, but different bands were selected for each site. Accuracy assessment of bathymetric maps produced using various calibration approaches and image types indicated that: 1) a linear d vs. Xrelation provided depth estimates nearly as accurate as a quadratic formulation; 2) panchromatic and pan-sharpened multispectral images with smaller 0.5 m pixels did not yield more reliable depth estimates than the original images; and 3) depth retrieval was less reliable in pools due to saturation of the radiance signal. This investigation thus demonstrated the feasibility, as well as the limitations, of measuring the bathymetry of clear, shallow gravel bed rivers from space.

  2. Gravel extraction and planform change in a wandering gravel-bed river: The River Wear, Northern England

    NASA Astrophysics Data System (ADS)

    Wishart, Duncan; Warburton, Jeff; Bracken, Louise

    2008-02-01

    Within-channel alluvial gravel extraction is one of the most important forms of anthropogenically induced morphological change in river channels. In British rivers commercial gravel extraction was widespread between the 1930s and 1960s, and limited gravel extraction operations to reduce flood risk or maintain navigation continue to the present day. Despite this, gravel extraction has received little attention in UK river studies. This paper examines the significance of within-channel gravel extraction, during the period 1945-1960, on the planform of the River Wear in northern England. The study focuses on two 3 km piedmont reaches at Wolsingham and Harperley Park, located at the margin of the upland zone. Examination of detailed archival accounts of the gravel extraction operations, supplemented by the analysis of aerial photographs has enabled the impact of gravel extraction on the channel of the River Wear to be determined. Sediment budget calculations suggest large sediment deficits in both study reaches, however, assessing potential impacts simply in terms of a sediment deficit may be misleading as channel adjustments depend on local factors and a detailed consideration of the reach-scale sediment budget. Differences in the nature of channel adjustments of both reaches were found to be primarily a function of the method of gravel extraction employed. Overall patterns of channel change along the extraction reaches, over the past 150 years, were similar to reaches where gravel extraction was not practiced. This highlights the difficulty of trying to establish the significance of different processes where both local (gravel extraction) and catchment-scale factors (climate and land use) are operating.

  3. Wellbore pressure differential control for gravel pack screen

    SciTech Connect

    Cornette, H.M.

    1993-08-10

    A method is described for minimizing cross-flow of fluid in a wellbore in an earth formation and fitted with a gravel packing and an auger-type gravel pack screen, comprising the steps of: providing an auger-type gravel pack screen having a generally tubular liner member defining a space therewithin; providing a quantity of wellbore fluid loss control material comprising a graded particulate salt disposed in said space which will provide a substantially impermeable barrier to the flow of fluid out of said space through said liner into said gravel packing and said earth formation; filling at least a portion of said space with said material; installing said screen in said gravel packing; removing said material from said space after installation of said screen in said gravel packing by entraining said material in a carrier fluid while allowing at least some of said material to flow out of said space through said screen to form a filter cake on at least one of said gravel packing and said earth formation to minimize said cross-flow of fluid into said earth formation.

  4. New tool designs for high rate gravel pack operations

    SciTech Connect

    Ross, C.M.

    1995-12-31

    Fracturing of the wellbore to improve hydrocarbon recovery has been a universally accepted practice in the oilfield. The fracturing procedures reduce skin by breaking through or bypassing near wellbore damage that inhibits production. In loosely consolidated formations, a propped fracture can reduce fluid velocity in the near wellbore region, which subsequently reduces fines migration that can plug the wellbore. Fracturing also provides highly conductive paths for gas and oil production. Gravel packing is another operation that is often needed during a well`s productive cycle. When a highly conductive fracture is created before a gravel packing operation is run, it has been found that well productivity increases. Performing the operations separately, however, diminishes the productivity gains because of formation damage that can occur between completion operations. A method of gravel packing that includes a tip-screenout-design fracturing procedure, performed with the gravel pack packer, screen, and blank in the hole, was proposed to allow the procedures to be performed simultaneously. This paper will describe the various types of gravel packing tools that are currently in use, their specific application, and a new series of gravel packing tools that was developed to resolve the difficulties that arose when the operations of fracturing and gravel packing were combined. Also discussed is the need that arose for tools that could sustain high flow rates in small casing diameters. Test results will be used to provide acceptable flow rates for different bore sizes.

  5. New tool designs for high rate gravel pack operations

    SciTech Connect

    Ross, C.M.

    1995-10-01

    A universally accepted practice in the oilfield has been fracturing of the wellbore to improve hydrocarbon recovery. Fracturing procedures reduce skin by breaking through or bypassing near wellbore damage that inhibits production. In loosely consolidated formations, a propped fracture can reduce fluid velocity in the near wellbore region, which subsequently reduces fines migration that can plug the wellbore. Fracturing also provides highly conductive paths for gas and oil production. Gravel packing is another operation that is often needed during a well`s productive cycle. When a highly-conductive fracture is created before a gravel packing operation is run, it has been found that well productivity increases. Performing the operations separately however, diminishes the productivity gains because of formation damage that can occur between completion operations. A method of gravel packing that includes a tip-screen-out-design fracturing procedure, performed with the gravel pack packer, screen, and blank in the hole, was proposed to allow the procedures to be performed simultaneously. This paper will describe the various types of gravel packing tools that are currently in use, their specific application, and a new series of gravel packing tools that was developed to resolve the difficulties that arose when the operations of fracturing and gravel packing were combined. Also discussed is the need that arose for tools that could sustain high flow rates in small casing diameters. Test results will be used to provide acceptable flow rates for different bore sizes.

  6. The Dispersion and Burial of Well-Mixed Gravels

    NASA Astrophysics Data System (ADS)

    Haschenburger, J. K.

    2012-12-01

    Over the last two decades, results from numerous tracing experiments have shed light on grain kinematics in gravel-bed channels, including the distance of grain displacement and the depth of vertical mixing. However, most of these studies report results for relatively short temporal and spatial scales, when the behavior of tagged gravels may not reflect the overall streambed dynamics. The purpose of this talk is to highlight the grain kinematics of well-mixed gravels. Field observations come from a tracing experiment operated for nearly 20 years in Carnation Creek, which is located on the west coast of Vancouver Island, Canada. The small gravel-bed river with pool-riffle-bar morphology and large woody debris experiences an average of 15 ± 5 floods per year, which facilitates frequent streambed activity and relatively high bed material transport rates typically under partial sediment transport conditions. The magnetically tagged gravels, which range in size from 16 to 180 mm, have been recovered more than 10 times over the study period. Evaluation of the spatial distribution of tagged gravels over time documents the complex evolution of streamwise dispersion. Once tracers are well mixed vertically, the displacement of mobile gravels is only partly influenced by the tracer starting position in the bed morphology and its depth of burial before a given flooding period.

  7. Denitrification in a Sand and Gravel Aquifer

    PubMed Central

    Smith, Richard L.; Duff, John H.

    1988-01-01

    Denitrification was assayed by the acetylene blockage technique in slurried core material obtained from a freshwater sand and gravel aquifer. The aquifer, which has been contaminated with treated sewage for more than 50 years, had a contaminant plume greater than 3.5-km long. Near the contaminant source, groundwater nitrate concentrations were greater than 1 mM, whereas 0.25 km downgradient the central portion of the contaminant plume was anoxic and contained no detectable nitrate. Samples were obtained along the longitudinal axis of the plume (0 to 0.25 km) at several depths from four sites. Denitrification was evident at in situ nitrate concentrations at all sites tested; rates ranged from 2.3 to 260 pmol of N2O produced (g of wet sediment)−1 h−1. Rates were highest nearest the contaminant source and decreased with increasing distance downgradient. Denitrification was the predominant nitrate-reducing activity; no evidence was found for nitrate reduction to ammonium at any site. Denitrifying activity was carbon limited and not nitrate limited, except when the ambient nitrate level was less than the detection limit, in which case, even when amended with high concentrations of glucose and nitrate, the capacity to denitrify on a short-term basis was lacking. These results demonstrate that denitrification can occur in groundwater systems and, thereby, serve as a mechanism for nitrate removal from groundwater. PMID:16347621

  8. 15. VIEW OF GRAVEL PLANT, WEST SIDE OF RIVER AND ...

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

    15. VIEW OF GRAVEL PLANT, WEST SIDE OF RIVER AND DOWNSTREAM OF DAM SITE WITH EMPLOYEE HOUSING AT RIGHT. TRAMWAY BUCKETS ARE CLEARLY VISIBLE, November 1, 1927 - Coolidge Dam, Gila River, Peridot, Gila County, AZ

  9. 29. photographer unknown 27 August 1935 GRAVEL AND SAND HOPPERS ...

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

    29. photographer unknown 27 August 1935 GRAVEL AND SAND HOPPERS IN CONCRETE PLANT. - Bonneville Project, Columbia River, 1 mile Northeast of Exit 40, off Interstate 84, Bonneville, Multnomah County, OR

  10. Advective-diffusive contaminant migration in unsaturated sand and gravel

    SciTech Connect

    Rowe, R.K.; Badv, K.

    1996-12-01

    A method is presented for estimating the diffusion coefficients for chloride and sodium in unsaturated coarse sand and fine gravel based on parameters obtained from saturated diffusion tests conducted for similar material. The method is tested by comparing the observed and predicted diffusion profiles through unsaturated soil. The method is shown to work well for predicting the advective-diffusive migration of chloride and sodium through a two-layer soil system consisting of a compacted clayey silt underlain by an unsaturated fine gravel. Over the range of conditions examined, it is concluded that existing solute transport theory along with the proposed procedure for estimating the unsaturated diffusion coefficients can adequately predict chloride and sodium diffusion through both unsaturated coarse sand and fine gravel as well as predict advective-diffusive transport through a compacted clayey layer and underlying unsaturated fine gravel.

  11. 6. VIEW OF BAMBOO GATE LEADING INTO WHITE GRAVEL AND ...

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

    6. VIEW OF BAMBOO GATE LEADING INTO WHITE GRAVEL AND ROCK CLUSTER GARDEN REMINISCENT OF RYOAN-JI TEMPLE GARDEN IN KYOTO - Kykuit, Japanese Gardens, 200 Lake Road, Pocantico Hills, Westchester County, NY

  12. Gravel addition as a habitat restoration technique for tailwaters

    Treesearch

    Ryan McManamay; D. Orth; Charles Dolloff; Mark Cantrell

    2010-01-01

    We assessed the efficacy of passive gravel addition at forming catostomid spawning habitat under various flow regimes in the Cheoah River, a high-gradient tailwater river in North Carolina. The purpose was to provide a case study that included recommendations for future applications. A total of 76.3 m3 (162 tons) of washed gravel (10-50 mm) was passively dumped down...

  13. The resuscitation of the term Bryn Mawr gravel

    USGS Publications Warehouse

    Bascom, Florence

    1925-01-01

    In the course of geologic and physiographic work in eastern Pennsylvania, it has seemed to the writer that the time was ripe for the restriction of the term Brandywine formation, now including presumably both Pliocene and Pleistocene gravels, and the reinstatement of the old term Bryn Mawr gravel for a portion of the divided Brandywine. A brief history of the nomenclature and usage involved will show the grounds for the choice of terms.

  14. Field experience in gravel packing the Dourado field, offshore Brazil

    SciTech Connect

    Santos, F.C.R.

    1995-12-31

    This paper describes the completion operations in the Dourado field, with emphasis on four major gravel packing problems: (1) formation taking excessive gravel; (2) failure of the gravel pack screens; (3) severe well productivity decline and (4) an unusual production casing buckling. The problem occurred in a new area of the field where the main reservoir, the Calumbi sandstone, is largely intercalated with plastic, water sensitive shale streaks. Presumably, stresses developed during gravel packing set off the creepage tendency of these streaks, which might be intensified by hydration upon rock imbibition with water-based completion and gravel carrier fluids. The result was a continuous migration of shale into adjacent permeable layers, leaving behind progressive void space, which allows for the excessive pumping of gravel. As the well was flowed, check-valve effect naturally ensued as lumps of dispersed shales concentrates around the wellbore; hence the decline on well productivity. Another consequence of the shale behavior was a detrimental effect in the wellbore stability, which reflected in buckling of the casing in front of the perforated interval. Finally, the screen failure, a less conjectural problem, was attributed only to poor manufacturing quality.

  15. Manganese removal in saturated gravel beds: Obtaining design criteria

    SciTech Connect

    Sikora, F.J.; Brodie, G.A.; Behrends, L.L.

    1996-12-31

    Manganese is difficult to remove in passive wetland systems due to high pH requirements for rapid Mn oxidation and solubilization of MnO{sub 2} in the presence of Fe. To achieve Mn removal below the federal requirement of 2 mg/L, gravel beds placed after wetlands that remove Fe has been proposed. Although some data is available on gravel beds, not enough is available to recommend design parameters for these systems under a range of operating conditions. A study is being conducted to obtain information on the required Mn loading rates and retention times for adequate Mn removal at the TVA constructed wetland research facility. Treatments consist of two Mn loading rates of 1.4 and 3.7 g/m{sup 2}/d and two types of gravel, namely limestone and river gravel. The treatments are replicated 3 times resulting in 12 experimental units. After 3 months of operation, limestone is proving to be more effective at removing Mn than river gravel. Compilation of operating parameters for Mn removal in gravel beds will benefit power utility and surface mining industries by yielding information on a passive system that is inexpensive relative to caustic alkaline drip.

  16. Effects of gravel mulch on emergency of galleta grass seedlings

    SciTech Connect

    Winkel, V.K.; Medrano, J.C.; Stanley, C.; Walo, M.D.

    1993-02-01

    Gravel mulches show promise as effective material on the US Dept. of Energy Nevada Test Site for stabilizing erosive soils and aiding plant establishment by conserving soil water. A greenhouse study was implemented to determine the effects of gravel mulch on seedling emergence and soil water, and optimal depths of gravel for various native plant species. Greenhouse flats were sown with seeds of nine species of native grasses, forbs, and shrubs. The flats were then treated with a variety of mulch treatments including, no mulch, a 1-cm layer of soil over seeds, and 2 to 3-cm and 4 to 5-cm layers of 3 to 25-mm mixed gravel. Superimposed over these treatments were 3 irrigation treatments. Seedling density data was collected daily, and soil water was monitored daily with the gravimetric method. This study showed that under a variety of soil water conditions, a 2--3 cm gravel layer may aid emergence of galleta grass. Results from this study also demonstrated that a deeper layer of gravel (4--5 cm) prohibits emergence, probably because it acts as a physical barrier to the seedlings. Galleta grass emergence can be used as a model for how other species might respond to these seedbed and irrigation treatments, provided they have adequate germination and are exposed to similar environmental conditions.

  17. Modification of fluvial gravel size by spawning salmonids

    SciTech Connect

    Kondolf, G.M. ); Sale, M.J. ); Wolman, M.G. )

    1993-07-01

    Salmonids (salmon and trout) winnow fine sediment from streambed gravels during construction of the nest or [open quotes]redd[close quotes] used for spawning and incubation of fertilized eggs. The gravels and interstitial fine sediments excavated during this process are exposed to currents and differently transported: Gravels move a short distance, while the fine sediments are swept further downstream from the redd. To quantify the resultant modification of particle size distributions in redds, the authors sampled redds and adjacent undisturbed gravels to document changes in size distributions. These data were compiled with previously published observations to analyze the general nature of size modification during spawning. The final percentage finer than 1 mm in the gravels, P1[sub f], is related to the initial percentage finer than 1 mm, P1[sub i], by the equation P1[sub f] = 0.63 P1[sub i]. Hydraulic variables (water surface slope, mean column velocity, depth, shear stress, unit stream power) explained little of the variance and did not appear in the optimal models. Because fisheries biologists are called upon to evaluate gravels as potential spawning sites, these findings should prove useful in such evaluations. 44 refs., 5 figs., 4 tabs.

  18. Laboratory measurements of gravel thermal properties. A methodology proposal

    NASA Astrophysics Data System (ADS)

    Cultrera, Matteo; Peron, Fabio; Bison, Paolo; Dalla Santa, Giorgia; Bertermann, David; Muller, Johannes; Bernardi, Adriana; Galgaro, Antonio

    2017-04-01

    Gravel thermal properties measurements at laboratory level is quite challenging due to several technical and logistic issues, mainly connected to the sediment sizes and the variability of their mineralogical composition. The direct measurement of gravel thermal properties usually are not able to involve a representative volume of geological material, consequently the thermal measurements performed produce much dispersed results and not consistent due to the large interstitial voids and the poor physical contact with the measuring sensors. With the aim of directly provide the measurement of the gravel thermal properties, a new methodology has been developed and some results are already available on several gravel deposits samples around Europe. Indeed, a single guarded hot plate Taurus Instruments TLP 800 measured the gravel thermal properties. Some instrumental adjustments were necessary to adapt the measuring devices and to finalize the thermal measurements on gravels at the IUAV FISTEC laboratory (Environmental Technical Physics Laboratory of Venice University). This device usually provides thermal measurements according to ISO 8302, ASTM C177, EN 1946-2, EN 12664, EN 12667 and EN 12939 for building materials. A preliminary calibration has been performed comparing the outcomes obtained with the single guarded hot plate with a needle probe of a portable thermal conductivity meter (ISOMET). Standard sand (ISO 67:2009) is used as reference material. This study is provided under the Cheap-GSHPs project that has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement no. 657982

  19. The sand-deposition impact of artificial gravel beds on the protection of the Mogao Grottoes.

    PubMed

    Li, Guo Shuai; Qu, Jian Jun; Li, Xu Zhi; Wang, Wan Fu

    2014-03-11

    Gravel beds can prevent sand-dust emission and weaken sand-dust flux. We used wind-tunnel experiments and field observations on artificial gravel beds above the Mogao Grottoes to quantify their impact. In the report, we identified a significant correlation between gravel roughness and its ability to trap wind-transported sand. The optimal combinations of gravel diameter and coverage were determined. The greatest roughness is achieved when small gravel coverage is 75%, medium 40% and large 45%. We found that initial wind speed and gravel coverage are the key factors controlling the amount of sand trapped by the gravel beds.

  20. The sand-deposition impact of artificial gravel beds on the protection of the Mogao Grottoes

    PubMed Central

    Li, Guo Shuai; Qu, Jian Jun; Li, Xu Zhi; Wang, Wan Fu

    2014-01-01

    Gravel beds can prevent sand-dust emission and weaken sand-dust flux. We used wind-tunnel experiments and field observations on artificial gravel beds above the Mogao Grottoes to quantify their impact. In the report, we identified a significant correlation between gravel roughness and its ability to trap wind-transported sand. The optimal combinations of gravel diameter and coverage were determined. The greatest roughness is achieved when small gravel coverage is 75%, medium 40% and large 45%. We found that initial wind speed and gravel coverage are the key factors controlling the amount of sand trapped by the gravel beds. PMID:24614183

  1. Beaver Dam Effects on Gravel Transport Patterns - a Case Study

    NASA Astrophysics Data System (ADS)

    Bunte, K.; Swingle, K. W.; Potyondy, J. P.; Abt, S. R.

    2011-12-01

    Beaver dams are numerous in mountain streams, but little is known about gravel transport in those streams. The dams may be fully functioning and retain all incoming sediment or partially permeable to sediment or be almost completely removed. Beaver dams in their various states of preservation can have a profound influence on stream morphology and bedload transport. During the spring of 2011, the authors made a time series study of bedload transport in a mountain stream dominated by beavers dams. Dams occurred with a frequency of one every 50 feet and showed a range of decay and fluvial influence. Gravel transport was sampled with bedload traps over a 2-month long snowmelt highflow season. The reach-average gradient was 0.03 and stream widths ranged from 3 to 8 m. The stream bed was incised 0.5 to 1.5 m deep into a floodplain and typically trapezoidal in its cross-sectional shape. Much of the floodplain consisted of filled-in beaver dams. Partially breached dams that were permeable to gravel transport acted as an obstacle, forcing the flow around sharp bends. Complex hydraulic conditions developed in the vicinity of the bends with backwater eddies upstream and downstream of the remnant dam. Wake eddies at the downstream side of dam remnants caused gravel deposits. The tortuous channel course around the bends caused strong secondary currents that forced gravel transport into a narrow pathway along one of the banks causing a strong lateral concentration of transport. The pathway had a bed of fine and medium gravel, while the remainder of the bed consisted mostly of coarse gravel and cobbles that became immobile shortly after peak flows. Tracer experiments indicated that most of the mobile gravel traveled along that bankward path, even though flow velocities and depths were considerably smaller than in the stream center. Over the highflow season, flows increased to about 160% of the 1.5 year recurrence interval (Q1.5) within about a week and then remained within the

  2. Innovative approach to modeling accident response of Gravel Gerties

    SciTech Connect

    Kramer, M.; McClure, P.; Sullivan, H.

    1997-08-01

    Recent safety analyses at nuclear explosive facilities have renewed interest in the accident phenomenology associated with explosions in nuclear explosive cells, which are commonly referred to as {open_quotes}Gravel Gerties.{close_quotes} The cells are used for the assembly and disassembly of nuclear explosives and are located in the Device Assembly Facility (DAF) at the Nevada Test Site (NTS) and at the Pantex facility. The cells are designed to mitigate the release of special nuclear material to the environment in the event of a detonation of high explosive within the Gravel Gertie. Although there are some subtle differences between the cells of DAF and Pantex, their general design, geometry, and configuration are similar. The cells consist of a round room approximately 10.4 m in diameter and 5.2 m high enclosed by 0.3-m-thick concrete. Each cell has a wire-rope cantenary roof overlain with gravel. The gravel is approximately 6.9 m deep at the center of the roof and decreases toward the outer edge of the cell. The cell is connected to a corridor and subsequent rooms through an interlocking blast door. In the event of a accidental explosion involving significant amounts of high explosive, the roof structure is lifted by the force of the explosion, the supporting cables break, the gravel is lifted by the blast (resulting in rapid venting of the cell), and the gravel roof collapses, filling the cell. The lifting and subsequent collapse of the gravel, which acts much like a piston, is very challenging to model.

  3. Gravel Particles Entrainment and Deposition under Unsteady Flow Conditions

    NASA Astrophysics Data System (ADS)

    Franca, M. J.; Altinakar, M. S.; Hassan, M. A.; Qu, Z.

    2014-12-01

    Spatial patterns of particle entrainment and deposition under unsteady flow regime were examined using coloured particles. The impact of three different basic hydrograph shapes (triangular, rising and falling) on the bedload rate of a gravel-bedded channel is experimentally analysed. The experiments were performed in a 16.8 m long glassed-walls tilting flume, with a 60 cm wide and 80 cm deep rectangular section, at the École Polytechnique Fédérale de Lausanne. A mobile 10 cm deep layer reach was made in the bed channel from x = 4.9 m to x = 14.1 m with a relatively uniform gravel of size 3 to 8 mm. A sediment trap is located immediately downstream the movable bed reach and no sediment feeding were imposed upstream. Eight 0.70 m long stripes of coloured sediments were laid over the natural gravel starting immediately upstream of the sediment trap. The thickness of the coloured gravel layer was about 3 to 4 cm (approximately 5 to 7 times D50). The total length of the reach covered with the coloured sediments was 5.6 m. After the experiments, approximately the top 2 cm of the gravel bed was sampled by strips of 0.175 m in the longitudinal direction, over the entire reach covered with sediments. These samples were then separated into gravels of different colours, and the dry weight of the sediments of each sample was measured. In addition, the gravel accumulated in the sediment trap was also separated into different colour groups, weighed separately. From the combined evaluation of the sediments trapped downstream and the sediments sampled throughout the channel, spatial patterns of entrainment and deposition rates are inferred. With this, back calculation of the depth of the active layer is performed and Wilcok's formulations on tracer dispersion and estimation of sediment transport is tested and discussed.

  4. Dispersion Rates of Gravel Sizes in a Natural Channel

    NASA Astrophysics Data System (ADS)

    Haschenburger, J. K.

    2011-12-01

    Sediment transfers in gravel-bed rivers involve the three-dimensional dispersion of mixed size sediment. Few studies are available to inform on the streamwise rate of gravel dispersion in natural channels, especially over a longer time scale. This research uses a gravel tracing program to quantify both the mean and maximum rates of different size fractions over 17 flood seasons. Empirical observations were collected in Carnation Creek, a small gravel-bed river with large woody debris located on the west coast of Vancouver Island, Canada. An average of 15 ± 5 floods per year facilitates frequent streambed activity and relatively high bed material transport rates, typically under partial sediment transport conditions. About 2000 magnetically tagged stones, ranging in size from 16 to 180 mm, were deployed on the bed surface between 1991 and 1992. Streamwise dispersion rates were quantified for the eight size fractions as virtual velocities based on 11 tracer recoveries completed between 1991 and 2008. Maximum velocities were calculated using the 10 largest values for each fraction. During the study period 258 floods capable of moving bedload occurred, with two exceeding the estimated bankfull discharge. The hydrological forcing driving the dispersion process was quantified by expended flow energy. Fractional virtual velocities as a function of flow energy are fairly well described by power functions. In absolute terms, finer gravels have higher rates of dispersion than coarser gravels as expected. A slowdown in mean velocities over time occurs more quickly with finer gravels; function exponents range from -0.2 to -0.5. Maximum velocities adjusted more quickly than mean values, with function exponents spanning from -0.4 to -0.8. These grain size differences contribute to the streamwise sorting of bed material.

  5. The gravel sand transition in a disturbed catchment

    NASA Astrophysics Data System (ADS)

    Knighton, A. David

    1999-03-01

    More than 40 million cubic metres of mining waste were supplied to the Ringarooma River between 1875 and 1984, leading to successive phases of aggradation and degradation. The natural bed material is gravel but, given the volume of introduced load and the fact that much of the input was less than 5 mm in diameter, the size composition of the bed changed from gravel to sand during the phase of downstream progressive aggradation. A very sharp gravel-sand transition developed in which median grain size decreased from over 30 mm to under 3 mm in less than 500 m. With upstream supplies of mining debris becoming depleted first, degradation followed the same downstream progressive pattern as aggradation, causing the transition to migrate downstream. By 1984, the river could be regarded as a series of zones, each characterized by a particular bed condition: a natural cobble-gravel bed, unaffected by mining inputs (0-32 km); pre-disturbance bed re-exposed by degradation over 35-40 years (32-53 km); sandy substrate with a gravel armour produced by differential transport during degradation (53-65 km); sand dominated but with developing surface patches of coarser material (65-75 km); sandy bed reflecting the size composition of the original mining input (75-118 km). Although the gravel-sand transition itself is sharp, the transitional zone is lengthy (53-75 km). As degradation continues, the gravel-sand transition is expected to progress downstream but it has remained in a stable position for 12 years. Indeed, two major floods during the period released large quantities of sand from the sub-armour layer and newly-formed banks of mine tailings, causing fining both above and below the transition. Surface grain size is an adjustable component in the transitional zone as the river strives to recover from a major anthropogenic disturbance.

  6. Recolonization of gravel habitats on Georges Bank (northwest Atlantic)

    USGS Publications Warehouse

    Collie, J.S.; Hermsen, J.M.; Valentine, P.C.

    2009-01-01

    Gravel habitats on continental shelves around the world support productive fisheries but are also vulnerable to disturbance from bottom fishing. We conducted a 2-year in situ experiment to measure the rate of colonization of a gravel habitat on northern Georges Bank in an area closed to fishing (Closed Area II) since December 1994. Three large (0.25 m2) sediment trays containing defaunated pebble gravel were deployed at a study site (47 m water depth) in July 1997 and recovered in June 1999. The undersides of the tray lids positioned 56 cm above the trays served as settlement panels over the same time period. We observed rapid colonization of the gravel substrate (56 species) and the settlement panels (35 species), indicating that colonization of gravel in this region is not limited by the supply of colonists. The species composition of the taxa found in the trays was broadly similar to that we collected over a 10-year period (1994-2004) in dredge samples from gravel sediments at the same site. The increase in abundance of animals in the gravel colonization trays was rapid and reached a level in 2 years that took 4.5 years to achieve in the surrounding gravel sediments once fishing had stopped, based on data from dredge sampling at this site. The increase in biomass of animals found in the sediment trays paralleled the trend of biomass increase observed in dredge samples over the same period (1997-1999) but was lower in value. These data suggest that after rapid initial increase in abundance of organisms, succession proceeded by increasing individual body size. A comparison of settlement panel and tray faunas revealed that the mean biomass of structure-forming epifauna (sponges, bryozoans, anemones, hydroids, colonial tube worms) on the panels was 8 times that found on the trays. Structure-forming taxa constituted 29% of the mean biomass of the panel fauna but only 5.5% of the tray fauna. By contrast, the mean biomass of scavengers (crabs, echinoderms, nudibranchs

  7. Flow Characteristics over a Gravel Bedform: Kaj River Case Study

    NASA Astrophysics Data System (ADS)

    Maddahi, Mohammad Reza; Afzalimehr, Hossein; Rowinski, Paweł M.

    2016-10-01

    The present study deals with the turbulence structure in order to better understand the interaction of bedform and flow characteristics in a gravel-bed river. Data measured above a bedform is used to analyze the importance of coherent structures in turbulent transfer. The Reynolds stress and turbulence intensity in stream-wise direction illustrate significant difference along the bedform, showing a three-layer distribution at the crest and a convex one at the downstream of bedform. Quadrant analysis technique is used to picture momentum exchange above the considered bedform and to find the dominant event in bursting process of the gravel bedform. Quadrant analysis demonstrates that the mechanisms of bedforms generation in sand and gravel-bed rivers are similar and sweep is the dominant event in both rivers.

  8. Liquid filtration properties in gravel foundation of railroad tracks

    NASA Astrophysics Data System (ADS)

    Strelkov, A.; Teplykh, S.; Bukhman, N.

    2016-08-01

    Railway bed gravel foundation has a constant permanent impact on urban ecology and ground surface. It is only natural that larger objects, such as railway stations, make broader impact. Surface run-off waters polluted by harmful substances existing in railroad track body (ballast section) flow along railroad tracks and within macadam, go down into subterranean ground flow and then enter neighbouring rivers and water basins. This paper presents analytic calculations and characteristics of surface run-off liquid filtration which flows through gravel multiple layers (railroad track ballast section). The authors analyse liquids with various density and viscosity flowing in multi-layer porous medium. The paper also describes liquid stationary and non-stationary weepage into gravel foundation of railroad tracks.

  9. Remote identification of a gravel laden Pleistocene river bed

    NASA Technical Reports Server (NTRS)

    Scholen, Douglas E.

    1993-01-01

    The abundance of gravel deposits is well known in certain areas across the Gulf of Mexico coastal plain, including lands within several National Forests. These Pleistocene gravels were deposited following periods of glacial buildup when ocean levels were down and the main river channels had cut deep gorges, leaving the subsidiary streams with increased gradients to reach the main channels. During the warm interglacial periods that followed each glaciation, melting ice brought heavy rainfall and torrents of runoff carrying huge sediment loads that separated into gravel banks below these steeper reaches where abraiding streams, developed. As the oceans rose again, filling in the main channels, these abraiding areas were gradually flattened and covered over by progressively finer material. Older terraces were uplifted by tectonic movements associated with the Gulf Coastal Plain, and the subsequent erosional processes gradually brought the gravels closer to the surface. The study area is located on the Kisatchie National Forest, in central Louisiana, near Alexandria. Details of the full study have been discussed elsewhere. The nearest source of chert is in the Ouachita Mountains located to the northeast. The Ouachita River flows south, out of these mountains, and in Pleistocene times probably carried these chert gravels into the vicinity of the present day Little River Basin which lies along the eastern boundary of the National Forest. Current day drainages cross the National Forest from west to east, emptying into the Little River on the east side. However, a north-south oriented ridge of hills along the west side of the Forest appears to be a recent uplift associated with the hinge line of the Mississippi River depositional basin further to the east, and 800,000 years ago, when these gravels were first deposited during the Williana interglacial period, the streams probably flowed east to west, from the Little River basin to the Red River basin on the west side of the

  10. On the dynamics of shallow gravel bed flow

    NASA Astrophysics Data System (ADS)

    Mohajeri, Seyed Hossein; Righetti, Maurizio; Wharton, Geraldene; Gurnell, Angela

    2013-04-01

    Flow dynamics on a gravel bed is a popular research subject because of environmental implications and especially in the presence of sediment transport. However, some features of flow dynamics on gravel beds are not completely understood and many questions remain open, especially in the context of the turbulence structure of the flow field and sediment transport. Due to the low submergence characteristics of the flow, the dynamics of the turbulent flow field, especially at the bed region, cannot be regarded as a classical boundary roughness problem, sensu Nikuradse (Nezu and Nakagawa, 1993) due to the strong spatial and temporal variation of the flow field. Over the past decade, in order to properly take into account the spatial heterogeneity, spatial averaging of time averaged values have become common. Besides,recently a trend to understand the role of gravel bed statistical properties, such as structure function of the bed elevation, on the statistics of the near-bed flow has been proposed. Although much research considers gravel beds by spatial averaging and research has been conducted on the effects of bed characteristics on near bed flow and sediment transport, only a few studies consider both together. In the present study, the results of 2D PIV measurement coupled with high accurate measurement of the gravel bed characteristics and the turbulence properties of the low submergence gravel bed flow as related to the bed properties are presented. The double averaging method was used in the analysis. Furthermore, in order to have a better insight into the dynamics of transport processes at the bed, a simple quadrant analysis, based on the Lu and Willmarth method, was implemented (Lu and Willmarth, 1973). Finally, the turbulent integral length scale was calculated both near and far from the gravel bed. The time and double averaged results show an agreement with the previous studies. Moreover, the result of quadrant analysis shows the sweep is dominant between

  11. Charred wood remains in the natufian sequence of el-Wad terrace (Israel): New insights into the climatic, environmental and cultural changes at the end of the Pleistocene

    NASA Astrophysics Data System (ADS)

    Caracuta, Valentina; Weinstein-Evron, Mina; Yeshurun, Reuven; Kaufman, Daniel; Tsatskin, Alexander; Boaretto, Elisabetta

    2016-01-01

    The major social and economic changes associated with the rise of a sedentary lifestyle and the gradual transition to food production in the southern Levant are often considered to have been triggered by climate changes at the end of the Pleistocene (∼20,000-11,000 years BP). This explanation, however, is biased by the scarcity of high-resolution climate records directly associated with human activity and the lack of refined palaeoecological studies from multi-stratified sites in the area. Here, we present the results of an anthracological analysis, carried out on charcoals collected along a continuous column of archaeological sediments in the Natufian site of el-Wad Terrace (Mount Carmel, Israel). We also present the carbon isotopes analysis of 14C-dated archaeological remains of Amygdalus sp. The analyses of charcoal shows the predominance of an oak forest including Quercus calliprinos and ithaburensis around the site during the Early Natufian building phase (∼14,600-13,700 cal BP), and the values of Δ13C point to a high rainfall rate. This period is followed by a marked decrease in the local rainfall between ∼13,700 and 12,000 cal BP). The reduction, culturally associated with the latest Early Natufian and the Late Natufian, is independently recorded by the speleothems of the region: Soreq Cave and Jerusalem Cave. This period incorporates an increase in drought tolerant species such as Amygdalus sp. Thermo-Mediterranean species, such as Olea europaea and Ceratonia siliqua, as well as Pistacia palaestina, which dominate the modern landscape, become established in the Holocene. We conclude that the Natufian settlement at el-Wad Terrace flourished in the context of oak forests, and subsequently occupation intensity decreased in concurrence to the drying trend. This shift does not correspond to the cultural typology (i.e. Early Natufian vs. Late Natufian). Human response to climate change at the terminal Pleistocene Levant was multifaceted and localized. Its

  12. Fine sediment erosion rate in immobile gravel bed

    NASA Astrophysics Data System (ADS)

    Tarekegn, T. H.

    2015-12-01

    The dynamics of fine sediment transport in immobile gravel bed is a complex process and is a common phenomenon downstream of dams during dam removal and flushing operations. Despite many developments in the field, the direct measurement of fine sediment erosion (entrainment) rates in immobile coarse beds remains challenging. We developed a new approach for measurement of fine sediment erosion rate in coarse immobile bed in laboratory experiment. The method uses single laser line, a video camera and a reflective mirror. It allows a non-intrusive, fast and accurate measurement of fine sediment erosion rate in running water and non-equilibrium transport conditions. The measurement method was conducted for flow depth that ranges from 3.0 cm to 8.0 cm. We present procedures developed to extract laser lines from series of images captured at high temporal resolution and to estimate rapid evolution of fine sediment erosion depth within the roughness layer of the immobile gravel bed. With the use of a reflective mirror the depth of erosion can be measured with sub-millimeter (350μm) resolution. The results of the measurements are used to describe vertical profile of fine sediment erosion rate in the gravel roughness layer and its spatial heterogeneity. The spatial pattern of erosion rates shows good agreement with gravel bed turbulent flow structures.

  13. An improved tri-tube cryogenic gravel sampler.

    Treesearch

    Fred H. Everest; Carl E. McLemore; John F. Ward

    1980-01-01

    The tri-tube cryogenic gravel sampler has been improved, and accessories have been developed that increase its reliability and safety of operation, reduce core extraction time, and allow accurate partitioning of cores into subsamples. The improved tri-tube sampler is one of the most versatile and efficient substrate sampling tools yet developed.

  14. New method for measuring water seepage through salmon spawning gravel.

    Treesearch

    Richard D. Orchard

    1988-01-01

    A new method, with heat as a tracer, was developed for measuring rate and direction of intragravel waterflow through salmon spawning gravel. A commercial flowmeter was calibrated in the laboratory under controlled environmental conditions. Flow measurements comparing the flowmeter with a dye-tracer method were made in an artificial stream channel at Young Bay and in...

  15. Gravel pit ponds as habitat enhancement for juvenile coho salmon.

    Treesearch

    M.D. Bryant

    1988-01-01

    Gravel pits built during road construction in the early 1970's near Yakutat, Alaska, filled with water and were connected to nearby rivers to allow juvenile salmonids to enter. Seasonal changes in population size, length and weight, and length frequencies of the coho salmon population were evaluated over a 2-year period. Numbers of coho salmon fluctuated, but two...

  16. Steam injection well gravel pack material of sintered bauxite

    SciTech Connect

    Elson, T. D.; Millhone, R. S.

    1985-08-27

    A packing material useful in a gravel pack for open or cased wells or in a prepack for use in steam or hot fluid injection and production wells. The packing material is a material which is insoluble in high temperature caustic fluids and subsurface formation fluids. Sintered bauxite is a claimed material.

  17. Steam injection well gravel prepack material of sintered bauxite

    SciTech Connect

    Elson, T. D.; Millhone, R. S.

    1985-10-22

    A packing material useful in a gravel pack for open or cased wells or in a prepack for use in steam or hot fluid injection and production wells. The packing material is a material which is insoluble in high temperature caustic fluids and subsurface formation fluids. Sintered bauxite is a claimed material.

  18. Evaluation of steam resistance of gravel-packing materials

    SciTech Connect

    Weaver, J.D.; Knox, J.A. )

    1992-05-01

    This paper compares the steam stability of common gravel-packing materials. The scope was limited to one set of downhole conditions. Results indicated that none of the commonly used materials were entirely satisfactory, but another material not normally used in the petroleum industry was found to give excellent results.

  19. Bed load transport in gravel-bed rivers

    Treesearch

    Jeffrey J. Barry

    2007-01-01

    Bed load transport is a fundamental physical process in alluvial rivers, building and maintaining a channel geometry that reflects both the quantity and timing of water and the volume and caliber of sediment delivered from the watershed. A variety of formulae have been developed to predict bed load transport in gravel-bed rivers, but testing of the equations in natural...

  20. Vortex model of open channel flows with gravel beds

    NASA Astrophysics Data System (ADS)

    Belcher, Brian James

    Turbulent structures are known to be important physical processes in gravel-bed rivers. A number of limitations exist that prohibit the advancement and prediction of turbulence structures for optimization of civil infrastructure, biological habitats and sediment transport in gravel-bed rivers. This includes measurement limitations that prohibit characterization of size and strength of turbulent structures in the riverine environment for different case studies as well as traditional numerical modeling limitations that prohibit modeling and prediction of turbulent structure for heterogeneous beds under high Reynolds number flows using the Navier-Stokes equations. While these limitations exist, researchers have developed various theories for the structure of turbulence in boundary layer flows including large eddies in gravel-bed rivers. While these theories have varied in details and applicable conditions, a common hypothesis has been a structural organization in the fluid which links eddies formed at the wall to coherent turbulent structures such as large eddies which may be observed vertically across the entire flow depth in an open channel. Recently physics has also seen the advancement of topological fluid mechanical ideas concerned with the study of vortex structures, braids, links and knots in velocity vector fields. In the present study the structural organization hypothesis is investigated with topological fluid mechanics and experimental results which are used to derive a vortex model for gravel-bed flows. Velocity field measurements in gravel-bed flow conditions in the laboratory were used to characterize temporal and spatial structures which may be attributed to vortex motions and reconnection phenomena. Turbulent velocity time series data were measured with ADV and decomposed using statistical decompositions to measure turbulent length scales. PIV was used to measure spatial velocity vector fields which were decomposed with filtering techniques for flow

  1. Fisher Sand & Gravel New Mexico, Inc. General Air Quality Permit: Related Documents

    EPA Pesticide Factsheets

    Documents related to the Fisher Sand & Gravel – New Mexico, Inc., Grey Mesa Gravel Pit General Air Quality Permit for New or Modified Minor Source Stone Quarrying, Crushing, and Screening Facilities in Indian Country.

  2. Sediment transport and resulting deposition in spawning gravels, north coastal California

    Treesearch

    Thomas E. Lisle

    1989-01-01

    Incubating salmonid eggs in streambeds are often threatened by deposition of fine sediment within the gravel. To relate sedimentation of spawning gravel beds to sediment transport, infiltration of fine sediment (

  3. Disturbance of fluvial gravel substrates by signal crayfish (Pacifastacus leniusculus)

    NASA Astrophysics Data System (ADS)

    Johnson, Matthew; Rice, Stephen; Reid, Ian

    2010-05-01

    The reworking of substrates by organisms, termed bioturbation, is considered a fundamental processes in marine and terrestrial environments but has remained relatively unstudied in fluvial environments. This studies looks at the bioturbation of fluvial gravel substrates by signal crayfish, an internationally important invasive species. We investigated the impact of signal crayfish activity in a laboratory flume. Bioturbation by crayfish on both loose arrangements of gravel and water-worked surfaces were studied and two sizes of narrowly-graded gravel were used; 11 - 16 mm and 16 - 22 mm. A laser scanner was used to obtain high resolution digital elevation models (DEMs) of gravel surfaces before and after crayfish activity. These DEMs were used to quantify topographic and structural changes to the surfaces due to the activity of crayfish. It was found that crayfish moved substantial quantities of material from all surfaces within six hours of introduction. The majority of the disturbance was associated with small scale (≤ 1 median grain diameter) movements of surface grains due to walking and foraging by crayfish. This textural change resulted in a structural alteration to the substrate surface. After six hours of crayfish activity, there was a 14% reduction in the imbrication of the grains from water-worked surfaces. Crayfish also constructed shallow pits and heaped excavated material into a series of mounds around its edge. Crayfish would always posture in pits in the same way. They would fold their vulnerable tails under their body and place their claws in front of their heads. When in pits crayfish predominately orientated themselves so they were facing an upstream direction. This implies that crayfish dig pits in order to streamline their bodies in the flow and lower their protrusion. Although pits and mounds contributed a relatively small proportion to the overall disturbance of substrates, they significantly increased the roughness of substrates. Pit and

  4. Sediment supply controls equilibrium channel geometry in gravel rivers

    PubMed Central

    Finnegan, Noah J.; Willenbring, Jane K.

    2017-01-01

    In many gravel-bedded rivers, floods that fill the channel banks create just enough shear stress to move the median-sized gravel particles on the bed surface (D50). Because this observation is common and is supported by theory, the coincidence of bankfull flow and the incipient motion of D50 has become a commonly used assumption. However, not all natural gravel channels actually conform to this simple relationship; some channels maintain bankfull stresses far in excess of the critical stress required to initiate sediment transport. We use a database of >300 gravel-bedded rivers and >600 10Be-derived erosion rates from across North America to explore the hypothesis that sediment supply drives the magnitude of bankfull shear stress relative to the critical stress required to mobilize the median bed surface grain size (τbf*/τc*). We find that τbf*/τc* is significantly higher in West Coast river reaches (2.35, n = 96) than in river reaches elsewhere on the continent (1.03, n = 245). This pattern parallels patterns in erosion rates (and hence sediment supplies). Supporting our hypothesis, we find a significant correlation between upstream erosion rate and local τbf*/τc* at sites where this comparison is possible. Our analysis reveals a decrease in bed surface armoring with increasing τbf*/τc*, suggesting channels accommodate changes in sediment supply through adjustments in bed surface grain size, as also shown through numerical modeling. Our findings demonstrate that sediment supply is encoded in the bankfull hydraulic geometry of gravel bedded channels through its control on bed surface grain size. PMID:28289212

  5. Sediment supply controls equilibrium channel geometry in gravel rivers.

    PubMed

    Pfeiffer, Allison M; Finnegan, Noah J; Willenbring, Jane K

    2017-03-28

    In many gravel-bedded rivers, floods that fill the channel banks create just enough shear stress to move the median-sized gravel particles on the bed surface (D50). Because this observation is common and is supported by theory, the coincidence of bankfull flow and the incipient motion of D50 has become a commonly used assumption. However, not all natural gravel channels actually conform to this simple relationship; some channels maintain bankfull stresses far in excess of the critical stress required to initiate sediment transport. We use a database of >300 gravel-bedded rivers and >600 (10)Be-derived erosion rates from across North America to explore the hypothesis that sediment supply drives the magnitude of bankfull shear stress relative to the critical stress required to mobilize the median bed surface grain size ([Formula: see text]). We find that [Formula: see text] is significantly higher in West Coast river reaches (2.35, n = 96) than in river reaches elsewhere on the continent (1.03, n = 245). This pattern parallels patterns in erosion rates (and hence sediment supplies). Supporting our hypothesis, we find a significant correlation between upstream erosion rate and local [Formula: see text] at sites where this comparison is possible. Our analysis reveals a decrease in bed surface armoring with increasing [Formula: see text], suggesting channels accommodate changes in sediment supply through adjustments in bed surface grain size, as also shown through numerical modeling. Our findings demonstrate that sediment supply is encoded in the bankfull hydraulic geometry of gravel bedded channels through its control on bed surface grain size.

  6. Sediment supply controls equilibrium channel geometry in gravel rivers

    NASA Astrophysics Data System (ADS)

    Pfeiffer, Allison M.; Finnegan, Noah J.; Willenbring, Jane K.

    2017-03-01

    In many gravel-bedded rivers, floods that fill the channel banks create just enough shear stress to move the median-sized gravel particles on the bed surface (D50). Because this observation is common and is supported by theory, the coincidence of bankfull flow and the incipient motion of D50 has become a commonly used assumption. However, not all natural gravel channels actually conform to this simple relationship; some channels maintain bankfull stresses far in excess of the critical stress required to initiate sediment transport. We use a database of >300 gravel-bedded rivers and >600 10Be-derived erosion rates from across North America to explore the hypothesis that sediment supply drives the magnitude of bankfull shear stress relative to the critical stress required to mobilize the median bed surface grain size (τbf*/τc*). We find that τbf*/τc* is significantly higher in West Coast river reaches (2.35, n = 96) than in river reaches elsewhere on the continent (1.03, n = 245). This pattern parallels patterns in erosion rates (and hence sediment supplies). Supporting our hypothesis, we find a significant correlation between upstream erosion rate and local τbf*/τc* at sites where this comparison is possible. Our analysis reveals a decrease in bed surface armoring with increasing τbf*/τc*, suggesting channels accommodate changes in sediment supply through adjustments in bed surface grain size, as also shown through numerical modeling. Our findings demonstrate that sediment supply is encoded in the bankfull hydraulic geometry of gravel bedded channels through its control on bed surface grain size.

  7. Improving sand and gravel utilization and land-use planning. - 3D-modelling gravel resources with geospatial data.

    NASA Astrophysics Data System (ADS)

    Rolstad Libach, Lars; Wolden, Knut; Dagestad, Atle; Eskil Larsen, Bjørn

    2017-04-01

    The Norwegian aggregate industry produces approximately 14 million tons of sand and gravel aggregates annually to a value of approximately 100 million Euros. Utilization of aggregates are often linked to land-use conflicts and complex environmental impacts at the extraction site. These topics are managed on a local municipal level in Norway. The Geological Survey of Norway has a database and a web map service with information about sand and gravel deposits with considerable volumes and an importance evaluation. Some of the deposits covers large areas where the land-use conflicts are high. To ease and improve land-use planning, safeguard other important resources like groundwater and sustainable utilization of sand and gravel resources - there is a need for more detailed information of already mapped important resources. Detailed 3D-models of gravel deposits is a tool for a better land-use- and resource management. By combining seismic, GPR and resistivity geophysical profile data, borehole data, quaternary maps and lidar surface data, it has been possible to make 3D-models of deposits and to further research the possibilities for distinguishing different qualities and volumes. Good datasets and a detailed resource map is a prerequisite to assess geological resources for planners, extractors and neighbours. Future challenges lies in use of, often old, geophysical data, and combining these. What kind of information is it possible to grasp from depth-data that actually argues for a more detailed delineation of resources?

  8. 40 CFR 436.30 - Applicability; description of the construction sand and gravel subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... construction sand and gravel subcategory. 436.30 Section 436.30 Protection of Environment ENVIRONMENTAL... CATEGORY Construction Sand and Gravel Subcategory § 436.30 Applicability; description of the construction sand and gravel subcategory. The provisions of this subpart are applicable to the mining and the...

  9. 32 CFR 644.505 - Disposal plan for embedded gravel, sand or stone.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 4 2011-07-01 2011-07-01 false Disposal plan for embedded gravel, sand or stone. 644.505 Section 644.505 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY... Gravel, Sand and Stone § 644.505 Disposal plan for embedded gravel, sand or stone. Prior to offering sand...

  10. 40 CFR 436.30 - Applicability; description of the construction sand and gravel subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... construction sand and gravel subcategory. 436.30 Section 436.30 Protection of Environment ENVIRONMENTAL... CATEGORY Construction Sand and Gravel Subcategory § 436.30 Applicability; description of the construction sand and gravel subcategory. The provisions of this subpart are applicable to the mining and the...

  11. 75 FR 3915 - Environmental Documents Prepared in Support of Sand and Gravel Activities on the Outer...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-25

    ... Minerals Management Service Environmental Documents Prepared in Support of Sand and Gravel Activities on... for three sand and gravel activities proposed on the Outer Continental Shelf (OCS) and described in... noncompetitive basis, the rights to OCS sand, gravel, or shell resources for shore protection, beach or wetlands...

  12. 32 CFR 644.505 - Disposal plan for embedded gravel, sand or stone.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 4 2010-07-01 2010-07-01 true Disposal plan for embedded gravel, sand or stone... (CONTINUED) REAL PROPERTY REAL ESTATE HANDBOOK Disposal Disposal of Standing Timber, Crops, and Embedded Gravel, Sand and Stone § 644.505 Disposal plan for embedded gravel, sand or stone. Prior to offering...

  13. 75 FR 68606 - Chetco River Gravel Mining Executive and Technical Teams; Notification of Availability of Documents.

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-08

    ... Department of the Army, Corps of Engineers Chetco River Gravel Mining Executive and Technical Teams... Chetco River Gravel Mining Executive and Technical Teams. These work products consist of meeting agendas, meeting minutes, reports, and other documents related to the proposed Chetco River Gravel Mining...

  14. Prediction of sand transport over immobile gravel from supply limited to capacity conditions

    USDA-ARS?s Scientific Manuscript database

    The prediction of the transport of sand in armored gravel reaches downstream of dams is complicated by variable bed conditions ranging from sand transported through gravel to sand in transport over buried gravel. Knowledge of the rate of sand transport in these conditions, however, is necessary for...

  15. 40 CFR 436.30 - Applicability; description of the construction sand and gravel subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... construction sand and gravel subcategory. 436.30 Section 436.30 Protection of Environment ENVIRONMENTAL... POINT SOURCE CATEGORY Construction Sand and Gravel Subcategory § 436.30 Applicability; description of the construction sand and gravel subcategory. The provisions of this subpart are applicable to the...

  16. 40 CFR 436.30 - Applicability; description of the construction sand and gravel subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... construction sand and gravel subcategory. 436.30 Section 436.30 Protection of Environment ENVIRONMENTAL... POINT SOURCE CATEGORY Construction Sand and Gravel Subcategory § 436.30 Applicability; description of the construction sand and gravel subcategory. The provisions of this subpart are applicable to the...

  17. 32 CFR 644.505 - Disposal plan for embedded gravel, sand or stone.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 4 2013-07-01 2013-07-01 false Disposal plan for embedded gravel, sand or stone. 644.505 Section 644.505 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY... Gravel, Sand and Stone § 644.505 Disposal plan for embedded gravel, sand or stone. Prior to offering sand...

  18. 40 CFR 436.30 - Applicability; description of the construction sand and gravel subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... construction sand and gravel subcategory. 436.30 Section 436.30 Protection of Environment ENVIRONMENTAL... POINT SOURCE CATEGORY Construction Sand and Gravel Subcategory § 436.30 Applicability; description of the construction sand and gravel subcategory. The provisions of this subpart are applicable to the...

  19. 32 CFR 644.505 - Disposal plan for embedded gravel, sand or stone.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 4 2012-07-01 2011-07-01 true Disposal plan for embedded gravel, sand or stone. 644.505 Section 644.505 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY... Gravel, Sand and Stone § 644.505 Disposal plan for embedded gravel, sand or stone. Prior to offering sand...

  20. 32 CFR 644.505 - Disposal plan for embedded gravel, sand or stone.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 4 2014-07-01 2013-07-01 true Disposal plan for embedded gravel, sand or stone. 644.505 Section 644.505 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY... Gravel, Sand and Stone § 644.505 Disposal plan for embedded gravel, sand or stone. Prior to offering sand...

  1. Macroinvertebrate Community responses to gravel addition in a Southeastern regulated river

    Treesearch

    Ryan A. McManamay; Donald J. Orth; A. Charles. Dolloff

    2013-01-01

    Sediment transport, one of the key processes of river systems, is altered or stopped by dams, leaving lower river reaches barren of sand and gravel, both of which are essential habitat for fish and macroinvertebrates. One way to compensate for losses in sediment is to supplement gravel to river reaches below impoundments. Because gravel addition has become a widespread...

  2. The Unified Gravel-Sand (TUGS) Model: Simulating the Transport of Gravel-Sand Mixtures in Rivers

    NASA Astrophysics Data System (ADS)

    Cui, Y.

    2006-12-01

    TUGS Model was developed by employing the surface-based bedload equation of Wilcock and Crowe (2003) and linking grain size distributions in the bedload, surface layer, and subsurface sediment deposit with the gravel transfer function of Hoey and Ferguson (1994) and Toro-Escobar et al. (1996), and a hypothetical sand transfer function. The unmodified model was applied to simulate the sedimentation process in Marmot Reservoir, Sandy River, Oregon and produced similar stratified sediment deposit as observed through coring exercises. The model was also examined with three runs of large-scale flume experiments conducted at St. Anthony Falls Laboratory (SAFL) by Seal et al. (1995). With a very minor modification to Wilcock and Crowe (2003) equation, the model excellently reproduced the longitudinal profiles, gravel grain size distributions and sand fractions in the deposits for all the three SAFL runs. Following its examination, TUGS model was applied to simulate the sediment transport dynamics in the Sandy River, Oregon under a few hypothetical scenarios, focusing on the dynamics of sand fractions in gravel-bedded channel deposits. Results of the exploratory runs on the Sandy River indicate that (a) surface and subsurface sand fractions generally increase in the downstream direction, similar to observed in the field; (b) sand fraction in the deposit is positively correlated with sand supply as expected; (c) extremely high sand supply under similar gravel supply and hydrologic conditions can transform the river into predominantly sand-bedded; (d) increased discharge under the same sand and gravel supply conditions results in decreased sand fraction in the deposit as expected; and (e) there can be significant increase in surface and subsurface sand fractions in the backwater zones near the mouth of the river as expected.

  3. Alluvial fan facies in Death Valley: Contrasts with fluvial gravels and implications for the interpretation of ancient fan'' gravels

    SciTech Connect

    Middleton, G.V. . Dept. of Geology)

    1993-03-01

    Sedimentary environments in Death Valley belong to three major groups: fans, washes, and playas. Fans in Death Valley include both diamicts and bedded gravels. Seven facies may be recognized. The diamicts include: (1) matrix-rich, coarse wackestones; (2) thin, matrix-rich, fine wackestones, that may show grading; (3) matrix-poor, coarse packstones, transitional to wackestones. The bedded facies include: (4) weakly bedded, poorly sorted packstones or grainstones, that show patchy imbrication, and cut-and-fill structures; (5) packed, imbricated cobble lenses, generally interbedded in facies 4; (6) distinctly bedded gravels, that are better bedded, finer and better sorted, and show better imbrication than facies 4, but still do not show clear separation of sand and gravel beds; (7) backfill cross-bedded gravels. Sand beds are not seen in fan deposits. Sand is present in eolian deposits of the playa, as plane-laminated, back-eddy deposits in Death Valley Wash, and as laminated or rippled sand in the Amargosa River, which drains into the south end of Death Valley. The most remarkable features of the fan and wash deposits are the very weak segregation of sand and gravel, and the absence of any lower flow-regime structures produced by ripples or dunes. During floods, the slope of fan and wash surfaces is steep enough to produce upper regime flows. Most fans in Death Valley itself are not strongly dominated by debris flow deposits (diamicts). Within a fan, facies vary little from proximal to distal regions, but may differ strongly from facies seen in adjacent fans.

  4. Experimental investigation of the influence of perforating on gravel-pack impairment

    SciTech Connect

    Blok, R.H.J.; Welling, R.W.F.; Venkitaraman, A.

    1996-12-31

    Analysis of the performance of perforated, gravel-packed wells compared with openhole gravel-packed wells has indicated that the perforation could be responsible for the low productivity of internally gravel-packed wells. A series of laboratory experiments on weak rock (UCS = 1200 psi) was conducted to quantify this. Castlegate sandstone rock samples, 7 in. in diameter and 18 in. long, were perforated with shaped charges under downhole conditions. The perforations were gravel packed by circulating a gravel slurry past the tunnel entrance while applying a differential pressure. The preperforation, post-perforation and post-gravel-pack productivities of the core samples were monitored at different flow rates (5 to 20 b/d/perf). Sectional photographs of the core samples were taken at post-gravel-pack conditions for qualitative analysis. Performance evaluation of gravel-packed {open_quotes}realistic perforations{close_quotes} (debris and loose sand in the tunnel removed by drawdown-induced flow) versus {open_quotes}ideal perforations{close_quotes} (debris and loose sand removed by external means) showed the post-gravel-pack productivities of realistic perforations to be much lower than ideal perforations in oil-phase as well as water-phase experiments. Injection of fluid after gravel packing only temporarily unplugged the perforation tunnel. The study shows the importance of fines-and debris-free perforation tunnels in maintaining the productivities; of gravel-packed completions.

  5. Channel erosion in steep gradient, gravel-paved streams

    SciTech Connect

    Lepp, L.R.; Koger, C.J.; Wheeler, J.A.

    1993-12-01

    Discharges were measured in steep gradient (> 5 percent) gravel-paved streams from 1988 to 1991 in order to empirically determine erosional thresholds based on sediment size, related to critical velocity, tractive force, and unit stream power. Results suggest that the empirical relationship between sediment size and unit stream power provides an accurate and simple methodology for determining the minimum erosion threshold discharge for steep gradient streams common in western Washington and other similar mountain terrains.

  6. Infiltration of Sand Into Gravel Riverbeds With Alternate Bar Topography

    NASA Astrophysics Data System (ADS)

    Leonardson, R.; Wydzga, M. A.; Venditti, J. G.; Dietrich, W. E.; Stacey, M. T.; Dracup, J. A.

    2006-12-01

    The hyporheic zone, which is comprised of the interconnected pore spaces in the bed of gravel rivers, plays a variety of roles in river health. It serves as a nutrient reservoir and refuge for aquatic organisms; supports surface water-groundwater exchange, which can mitigate flooding and improve water supply reliability; and stores organic matter, heavy metals, and other pollutants. When fine sediment (sand and silt) fills the pore spaces of the hyporheic zone, these functions are compromised. A number of one-dimensional laboratory studies have explored infiltration of sand into stable, flat (plane-bed), gravel riverbeds. The depth and volumetric content of sand infiltrated under such conditions are functions of sediment supply and the grain size distributions of the bed (gravel) and the sand in bedload. This study examines whether the relationships established in plane-bed experiments suffice to explain infiltration into a bed with alternate-bar topography. We present results from an infiltration experiment performed on a 2.7m x 55m laboratory flume at St. Anthony Falls Laboratory in Minneapolis. In this experiment, sand (D50 = 0.4mm) was infiltrated into a gravel (D50 = 9.2mm) bed with alternate bars, under low flow (35 lps). After infiltration, the bed was excavated at 3-6 sites in each of 5 cross-sections, chosen to represent a variety of topographic and flow conditions (e.g. head of bar, top of bar and deep channel, cross-channel). Bed samples are analyzed for depth of infiltration, sand content, and grain size distribution. We present the spatial patterns of depth and content of sand infiltrated, in relation to bed surface topography and surface water flow path. Ongoing research will couple the characteristics of this spatial pattern with sediment routing.

  7. Completion and production results from alternate-path gravel-packed wells

    SciTech Connect

    Bryant, D.W.; Jones, L.G.

    1995-09-01

    A successful gravel pack requires two things: perforations packed with gravel-pack sand and a completely packed annulus. Failure to obtain either one can result in low productivity and/or a sand-producing gravel pack. Alternate-path gravel packing ensures that the annulus will be completely packed and that all perforations taking fluid will be packed with gravel-pack sand. Altercate-path gravel packing has provided long and highly productive completions without any sand production. This paper presents completion data and production results from 39 wells completed with the alternate-path gravel-pack technique. The completion data include completion length, net perforations, carrier fluid, sand placement outside casing, workover fluid, and return rate during packaging. Production results include qualitative discussion of all completions with quantitative results, including permeability-thickness product and skin on select completions.

  8. The design method of a dam on gravel stream

    SciTech Connect

    Ni, W.B.; Wu, S.J.; Huang, C.Y.

    1995-12-31

    Due to the intense requirements of electricity and water supply in the past decades, large number of dams, reservoirs and mobile barrages have been completed in Taiwan. These hydraulic structures almost occupied all the sound rock foundations with little overburdens. This indicates that the future ones have to face the situation of high overburdens. Special considerations should be taken to overcome the difficulties of water tight requirement and stability of structures. A case study is presented in this paper. It is a dam built for the purpose of hydropower generation and water supply, and is constructed on a gravel stream with 40 m of overburdens. Design method of this dam is discussed in this paper. Curtain grouting is performed in this dam to reduce the high permeability of gravel to an acceptable level. Caissons are chosen to be the structural foundations in this case study to support heavy loads of the dam and to reduce the difficulty of curtain grouting. Another problem for a dam built on gravel stream is the damage of abrasion and erosion to the stilling basin slabs, the sluice way aprons and the spillway aprons. Discussions on the abrasion-erosion resistant materials are also given in this paper.

  9. Bed Mobility on the Deschutes River, Oregon: Tracer Gravel Results

    NASA Astrophysics Data System (ADS)

    Kondolf, G. M.; Williams, J.

    2003-12-01

    The Deschutes River, drainage area 20,250 km2 near Madras, Oregon, is a gravel-bedded river, impounded since 1957 by three dams in the Pelton-Round Butte hydroelectric project, operated by Portland General Electric (PGE). Salmon spawning has declined in the reach below the dams since their construction, so possible project effects on spawning habitat are an issue of concern in relicensing of the project. Consultants to PGE applied the Parker bedload transport function to several sites below the hydroelectric dams; they concluded that the entrainment threshold flow was 340 m3s-1, and that the bed had been mobile only 25 days in the 72-year period of record from 1925-1996. However, their model was not calibrated with any actual field data of bed mobility or bedload transport, and the calculations were for full bed mobility, ignoring potentially significant bedload transport that might occur at a condition of partial mobility. To redress that lack of field data, we placed tracer gravels in the bed at three sites below the dams. In 2002 tracer gravels moved at one of the three sites after a flow of 150 m3s-1 (128-mm stones moved up to 1 m). The minor movement suggests that the bed is just beginning to move at 150 m3s-1, but indicates that the previously assumed entrainment threshold of 340 m3s-1 is too high.

  10. Gravel packing a 2,400-ft openhole horizontal interval

    SciTech Connect

    Duhon, P.; Holley, A.; Gardiner, N.; Grigsby, T.

    1998-09-01

    A typical economic requirement of most high-cost deepwater development projects is high-initial-rate (> 15,000-B/D oil wells or > 70-MMcf/D gas wells) completions. To achieve these rates from pay sands in this field, 2,000--2,500-ft horizontal completions are used. Conventional openhole horizontal completions have been used in the Gulf of Mexico (GOM) since the early 1990`s. However, the number of failures experienced by some operators has raised questions about the reliability of this type of completion. In deepwater projects, high-rate production and completion reliability present major challenges to operators, and traditional methods of sand control often have not been able to satisfy the changing conditions. The full-length paper presents a solution that combines gravel packing, enhanced downhole-tool capability, and advanced fluid technology to solve sand-control problems. The successful application of the first extended, horizontal openhole gravel packs in the northern GOM proved that gravel packing can be applied successfully to extended horizontal boreholes.

  11. Deschutes River Spawning Gravel Study, Volume I, Final Report.

    SciTech Connect

    Huntington, Charles W.

    1985-09-01

    Spawning habitat in the Deschutes River was inventoried, gravel permeability and composition were sampled at selected gravel bars, historical flow records for the Deschutes were analyzed, salmon and trout utilization of spawning habitat was examined, and potential methods of enhancing spawning habitat in the river were explored. Some changes in river conditions since the mid-1960's were identified, including a reduction in spawning habitat immediately downstream from the hydroelectric complex. The 1964 flood was identified as a factor which profoundly affected spawning habitat in the river, and which greatly complicated efforts to identify recent changes which could be attributed to the hydrocomplex. A baseline on present gravel quality at both chinook and steelhead spawning areas in the river was established using a freeze-core methodology. Recommendations are made for enhancing spawning habitat in the Deschutes River, if it is independently determined that spawning habitat is presently limiting populations of summer steelhead or fall chinook in the river. 53 refs., 40 figs., 21 tabs.

  12. Development of an active behavioural physiotherapy intervention (ABPI) for acute whiplash-associated disorder (WAD) II management: a modified Delphi study

    PubMed Central

    Wiangkham, Taweewat; Duda, Joan; Haque, M Sayeed; Rushton, Alison

    2016-01-01

    Objective To develop an active behavioural physiotherapy intervention (ABPI) for managing acute whiplash-associated disorder (WAD) II using a modified Delphi method to develop consensus for the basic features of the ABPI. Design Modified Delphi study. Our systematic review and meta-analysis evaluating conservative management for acute WADII found that a combined ABPI may be a useful intervention to prevent patients progressing to chronicity. No previous research has considered a combined behavioural approach and active physiotherapy in the management of acute WADII patients. The ABPI was therefore developed using a rigorous consensus method using international research and local clinical whiplash experts. Descriptive statistics were used to assess consensus in each round. Setting Online international survey. Participants A purposive sample of 97 potential participants (aiming to recruit n=30) consisting of international research whiplash experts, UK private physiotherapists and UK postgraduate musculoskeletal physiotherapy students were invited to participate via electronic mail with an attached participant information sheet and consent form. Results 36 individuals signed and returned the consent form. In round 1, 32/36 participants (response rate=89%, mean age±SD=36.03±13.22 years) across 8 countries (Australia, Finland, Greece, India, Netherlands, Norway, Sweden and UK) contributed to round 1 questionnaire. Response rates were 78% and 75% for rounds 2 and 3, respectively. Following round 3, 12 underlying principles (eg, return to normal function as soon as possible, pain management, encouragement of self-management, reduce fear avoidance and anxiety) achieved consensus. The treatment components reaching consensus included behavioural (eg, education, reassurance, self-management) and physiotherapy components (eg, exercises for stability and mobility). No passive intervention achieved consensus. Conclusions Experts suggested and agreed the underlying principles

  13. Prevalence of anaemia among Quranic school (Khalawi) students (Heiran)in Wad El Magboul village, rural Rufaa, Gezira State, Central Sudan: a cross sectional study

    PubMed Central

    Eltayeb, Mohammed Saeed Elsamani; Elsaeed, Awad Eseed; Mohamedani, Ahmed Abdalla; Assayed, Abbas Abdalrahman

    2016-01-01

    Introduction This is a cross sectional descriptive community-based study. The aim was to assess the prevalence of anaemia among quranic schoolchildren in khalawi Wad EL Magboul village, rural Rufaa, Gezira State, central Sudan. Methods A sample of 180 male participants were included in the study. Informed consent was obtained. Venous blood samples were obtained to measure the hematological parameters and blood films for malaria parasites. Urine and stool analyses were also done. Data were analyzed using SPSS. Results The mean age of participants was 12.31 years (SD +/- 2.26). The mean Hb value was 11.75g/dl and it was statistically significant correlation when compared with the mean Hb reference value (13.5g/dl) P value 0,000 (95% CI). Regarding period of stay in the khalwa up to the time of the study, 88 (49.28%) for one year, 54 (30.24%) for 2 years, 22 (12.32%) for 3 years and 16 (8.96%) for more than 3 years. About 77 students (42.78%) were pale on clinical examination. The Mean Cell Hemoglobin (MCH) mean value was 25.58 pg ( 3.55). Many conditions known to be associated with anemia were found; 49 students (27.2%) had a positive blood films for falciparum malaria, 14 students (7.8%) were found to have haematuria and ova of S. haematobium, In169 students (93.4%) stool examination was negative , while 11 students (6.6%) had intestinal worms (Enterobius vermicularis). Conclusion Majority of the study participants had iron deficiency anaemia, followed by haemolytic, macrocytic and sickle cell anaemia. This might have negative health and educational implications. PMID:27800099

  14. Prevalence of anaemia among Quranic school (Khalawi) students (Heiran)in Wad El Magboul village, rural Rufaa, Gezira State, Central Sudan: a cross sectional study.

    PubMed

    Eltayeb, Mohammed Saeed Elsamani; Elsaeed, Awad Eseed; Mohamedani, Ahmed Abdalla; Assayed, Abbas Abdalrahman

    2016-01-01

    This is a cross sectional descriptive community-based study. The aim was to assess the prevalence of anaemia among quranic schoolchildren in khalawi Wad EL Magboul village, rural Rufaa, Gezira State, central Sudan. A sample of 180 male participants were included in the study. Informed consent was obtained. Venous blood samples were obtained to measure the hematological parameters and blood films for malaria parasites. Urine and stool analyses were also done. Data were analyzed using SPSS. The mean age of participants was 12.31 years (SD +/- 2.26). The mean Hb value was 11.75g/dl and it was statistically significant correlation when compared with the mean Hb reference value (13.5g/dl) P value 0,000 (95% CI). Regarding period of stay in the khalwa up to the time of the study, 88 (49.28%) for one year, 54 (30.24%) for 2 years, 22 (12.32%) for 3 years and 16 (8.96%) for more than 3 years. About 77 students (42.78%) were pale on clinical examination. The Mean Cell Hemoglobin (MCH) mean value was 25.58 pg ( 3.55). Many conditions known to be associated with anemia were found; 49 students (27.2%) had a positive blood films for falciparum malaria, 14 students (7.8%) were found to have haematuria and ova of S. haematobium, In169 students (93.4%) stool examination was negative , while 11 students (6.6%) had intestinal worms (Enterobius vermicularis). Majority of the study participants had iron deficiency anaemia, followed by haemolytic, macrocytic and sickle cell anaemia. This might have negative health and educational implications.

  15. Mechanical resistance properties of gravel used in subsurface flow constructed wetlands: implications for clogging.

    PubMed

    Pedescoll, Anna; Passos, Fabiana; Alba, Elisenda; García, Joan; Puigagut, Jaume

    2011-01-01

    Gravel constitutes the filter medium in subsurface flow constructed wetlands (SSF CWs) and its porosity and hydraulic conductivity decrease over time (clogging), limiting the lifespan of the systems. Using gravel of poor quality accelerates clogging in wetlands. In this study, gravel samples from six different wetland systems were compared with regards to their mineral composition and mechanical resistance properties. Results showed that both mineralogy and texture are related to mechanical resistance. Accordingly, gravel with high content of quartz (> 80%) showed a lower percentage of broken particles (0.18-1.03%) than those with lower content of quartz (2.42-4.56% media broken). Although granite is formed by high durability minerals, its non-uniform texture results in a lower resistance to abrasion (ca. 10% less resistance than calcareous gravel). Therefore, it is recommended to use gravels composed mainly of quartz or, when it is not available, limestone gravels (rounded and uniform) are recommended instead. The resistance to abrasion (LAA test) seems to be a good indicator to determine the mechanical properties of gravels used in CWs. It is recommended to use gravels with LAA below 30% in order to avoid a rapid clogging due to gravel crumbling and subsequent mineral solids accumulation.

  16. The effect of coarse gravel on cohesive sediment entrapment in an annular flume

    NASA Astrophysics Data System (ADS)

    Glasbergen, K.; Stone, M.; Krishnappan, B.; Dixon, J.; Silins, U.

    2015-03-01

    While cohesive sediment generally represents a small fraction (<0.5%) of the total sediment mass stored in gravel-bed rivers, it can strongly influence physical and biogeochemical processes in the hyporheic zone and alter aquatic habitat. This research was conducted to examine mechanisms governing the interaction of cohesive sediments with gravel beds in the Elbow River, Alberta, Canada. A series of erosion and deposition experiments with and without a gravel bed were conducted in a 5-m diameter annular flume. The critical shear stress for deposition and erosion of cohesive sediment without gravel was 0.115 Pa and 0.212 Pa, respectively. In experiments with a gravel bed, cohesive sediment moved from the water column into the gravel bed via the coupling of surface and pore water flow. Once in the gravel bed, cohesive sediments were not mobilized under the maximum applied shear stresses (1.11 Pa) used in the experiment. The gravel bed had an entrapment coefficient (ratio between the entrapment flux and the settling flux) of 0.2. Accordingly, when flow conditions are sufficient to produce a shear stress that will mobilize the armour layer of the gravel bed (>16 Pa), cohesive materials trapped within the gravel bed will be entrained and transported into the Glenmore Reservoir, where sediment-associated nutrients may pose treatment challenges to the drinking water supply.

  17. The effect of gravel size fraction on the distribution coefficients of selected radionuclides.

    PubMed

    Um, Wooyong; Serne, R Jeffrey; Last, George V; Clayton, Ray E; Glossbrenner, Ellwood T

    2009-06-26

    This manuscript addresses the consequences of the common practice of assuming that the gravel fraction of sediments does not participate in sorption reactions and thus sorption quantified by the distribution coefficient (K(d)) construct can be estimated from laboratory tests on sediments less than 2 mm size fraction. However, this common assumption can lead to inaccurate estimates of the mobility and sorption affinity of many radionuclides (e.g., Tc, U, and Np) on gravel dominated sediments at the Hanford Site and other locations. Laboratory batch sorption experiments showed that the distribution coefficients measured using only sediment less than 2 mm size fraction and correcting for inert gravel fraction were not in agreement with those obtained from the bulk sediments including gravel (larger than 2 mm size fraction), depending on the radionuclide. The least reactive radionuclide, Tc had K(d) values for bulk sediment with negligible deviations from the inert gravel corrected K(d) values measured on less than 2 mm size fraction. However, differences between measured K(d) values using sediment less than 2 mm size fraction and the K(d) values on the bulk sediment were significant for intermediately and strongly reactive radionuclides such as U and Np, especially on the sediment with gravel fractions that contained highly reactive sites. Highly reactive sites in the gravel fraction were attributed to the presence of Fe oxide coatings and/or reactive fracture faces on the gravel surfaces. Gravel correction factors that use the sum of the K(d)(,<2 mm) and K(d)(,>2 mm) values to estimate the K(d) for the bulk sediment were found to best describe K(d) values for radionuclides on the bulk sediment. Gravel correction factors should not be neglected to predict precisely the sorption capacity of the bulk sediments that contain more than 30% gravel. In addition, more detailed characterization of gravel surfaces should be conducted to identify whether higher reactive sorbents

  18. The effect of gravel size fraction on the distribution coefficients of selected radionuclides

    SciTech Connect

    Um, Wooyong; Serne, R. Jeffrey; Last, George V.; Clayton, Ray E.; Glossbrenner, Ellwood T.

    2009-06-26

    This manuscript addresses the consequences of the common practice of assuming that the gravel fraction of sediments does not participate in sorption reactions and thus sorption quantified by the distribution coefficient (Kd) construct can be estimated from laboratory tests on sediments less than 2 mm size fraction. However, this common assumption can lead to inaccurate estimates of the mobility and sorption affinity of many radionuclides (e.g., Tc, U, and Np) on gravel dominated sediments at the Hanford Site and other locations. Laboratory batch sorption experiments showed that the distribution coefficients measured using only sediment less than 2 mm size fraction and correcting for inert gravel fraction were not in agreement with those obtained from the bulk sediments including gravel (larger than 2 mm size fraction), depending on the radionuclide. The least reactive radionuclide, Tc had Kd values for bulk sediment with negligible deviations from the inert gravel corrected Kd values measured on less than 2 mm size fraction. However, differences between measured Kd values using sediment less than 2 mm size fraction and the Kd values on the bulk sediment were significant for intermediately and strongly reactive radionuclides such as U and Np, especially on the sediment with gravel fractions that contained highly reactive sites. Highly reactive sites in the gravel fraction were attributed to the presence of Fe oxide coatings and/or reactive fracture faces on the gravel surfaces. Gravel correction factors that use the sum of the Kd,<2 mm and Kd,>2 mm values to estimate the Kd for the bulk sediment were found to best describe Kd values for radionuclides on the bulk sediment. Gravel correction factors should not be neglected to predict precisely the sorption capacity of the bulk sediments that contain more than 30% gravel. In addition, more detailed characterization of gravel surfaces should be conducted to identify whether higher reactive sorbents are present in the

  19. Gravel sediment routing from widespread, low-intensity landscape disturbance, Current River basin, Missouri

    USGS Publications Warehouse

    Jacobson, R.B.; Gran, K.B.

    1999-01-01

    During the last 160 years, land-use changes in the Ozarks have had the potential to cause widespread, low-intensity delivery of excess amounts of gravel-sized sediment to stream channels. Previous studies have indicated that this excess gravel bedload is moving in wave-like forms through Ozarks drainage basins. The longitudinal, areal distribution of gravel bars along 160 km of the Current River, Missouri, was evaluated to determine the relative effects of valley-scale controls, tributary basin characteristics, and lagged sediment transport in creating areas of gravel accumulations. The longitudinal distribution of gravel-bar area shows a broad scale wave-like form with increases in gravel-bar area weakly associated with tributary junctions. Secondary peaks of gravel area with 1.8-4.1 km spacing (disturbance reaches) are superimposed on the broad form. Variations in valley width explain some, but not all, of the short-spacing variation in gravel-bar area. Among variables describing tributary drainage basin morphometry, present-day land use and geologic characteristics, only drainage area and road density relate even weakly to gravel-bar areal inventories. A simple, channel network-based sediment routing model shows that many of the features of the observed longitudinal gravel distribution can be replicated by uniform transport of sediment from widespread disturbances through a channel network. These results indicate that lagged sediment transport may have a dominant effect on the synoptic spatial distribution of gravel in Ozarks streams; present-day land uses are only weakly associated with present-day gravel inventories; and valley-scale characteristics have secondary controls on gravel accumulations in disturbance reaches.

  20. Salmon as biogeomorphic agents in gravel-bed rivers (Invited)

    NASA Astrophysics Data System (ADS)

    Hassan, M. A.

    2010-12-01

    Spawning salmon have been known to affect streambed texture, influence sediment transport, and play an important geomorphological role in streams by digging nests or redds. We examined the impact of salmon and floods on channel morphology, bed material dispersion and yield, bed surface texture and stability, fine sediment dynamics and nutrient retention of small gravel bed streams in British Columbia, Canada. Channel morphology and dynamics of a large number of streams in British Columbia are partially or wholly affected by fish bioturbation. The scale of the impact is controlled by the salmon species, population density, and channel size and characteristics. Sediment transport measurements show that salmon play a significant role in erosion and deposition within the channel by promoting vertical and longitudinal mixing of the substrate, as well as by changing the relative mobility of the gravel on the bed. The action of salmon bioturbation promotes distinctive bedforms and packing of sediment grains. In streams with dense populations of sockeye or chum salmon the whole surface of spawning reaches may be modified, as bars are excavated and pools are filled. For chinook salmon the organization of spawning bedforms ranges from scattered mounds or ‘gravel pile-ups’ to well-ordered dunes. Such dunes extend for hundreds of meters to kilometres along the river bed. They exhibit amplitudes of more than one metre and wavelengths of 10 to 15 m. Our conclusion that mass-spawning fish can dominate sediment transport in mountain drainage basins has fundamental implications for understanding channel morphology, aquatic ecosystem dynamics, stream responses to environmental change, and river restoration programs.

  1. Deposition of uranium precipitaties in dolomitic gravel fill

    SciTech Connect

    Phillips, Debra H.; Watson, David B; Kelly, Shelly D; Ravel, Bruce; Kemner, Kenneth M

    2008-06-01

    Uranium-containing precipitates have been observed in a dolomitic gravel fill near the Department of Energy (DOE) S-3 Ponds former waste disposal site as a result of exposure to acidic (pH 3.4) groundwater contaminated with U (33 mg L{sup -1}), Al{sup 3+} (900 mg L{sup -1}), and NO{sub 3}{sup -} (14000 mg L{sup -1}). The U containing precipitates fluoresce a bright green under ultraviolet (UV) short-wave light which identify U-rich coatings on the gravel. Scanning electron microscopy (SEM) microprobe analysis show U concentration ranges from 1.6-19.8% (average of 7%) within the coatings with higher concentrations at the interface of the dolomite fragments. X-ray absorption near edge structure spectroscopy (XANES) indicate that the U is hexavalent and extended X-ray absorption fine structure spectroscopy (EXAFS) shows that the uranyl is coordinated by carbonate. The exact nature of the uranyl carbonates are difficult to determine, but some are best described by a split K{sup +}-like shell similar to grimselite [K{sub 4}Na(UO{sub 2})(CO{sub 3}){sub 3} {center_dot} H{sub 2}O] and other regions are better described by a single Ca{sup 2+}-like shell similar to liebigite [Ca{sub 2}(UO{sub 2})(CO{sub 3}){sub 3} {center_dot} 11(H{sub 2}O)] or andersonite [Na{sub 2}CaUO{sub 2}(CO{sub 3}){sub 3} {center_dot} 6H{sub 2}O]. The U precipitates are found in the form of white to light yellow cracked-formations as coatings on the dolomite gravel and as detached individual precipitates, and are associated with amorphous basalumnite [Al{sub 4}(SO{sub 4})(OH){sub 10} {center_dot} 4H{sub 2}O].

  2. Deposition of uranium precipitates in dolomitic gravel fill.

    SciTech Connect

    Phillips, D. H.; Watson, D. B.; Kelly, S. D.; Ravel, B.; Kemner, K. M.; Biosciences Division; Queens Univ.; ORNL

    2008-01-01

    Uranium-containing precipitates have been observed in a dolomitic gravel fill near the Department of Energy (DOE) S-3 Ponds former waste disposal site as a result of exposure to acidic (pH 3.4) groundwater contaminated with U (33 mg L{sup -1}), Al{sup 3+} (900 mg L{sup -1}), and NO{sub 3}{sup -} (14000 mg L{sup -1}). The U containing precipitates fluoresce a bright green under ultraviolet (UV) short-wave light which identify U-rich coatings on the gravel. Scanning electron microscopy (SEM) microprobe analysis show U concentration ranges from 1.6?19.8% (average of 7%) within the coatings with higher concentrations at the interface of the dolomite fragments. X-ray absorption near edge structure spectroscopy (XANES) indicate that the U is hexavalent and extended X-ray absorption fine structure spectroscopy (EXAFS) shows that the uranyl is coordinated by carbonate. The exact nature of the uranyl carbonates are difficult to determine, but some are best described by a split K{sup +}-like shell similar to grimselite [K{sub 4}Na(UO{sub 2})(CO{sub 3}){sub 3} {center_dot} H{sub 2}O] and other regions are better described by a single Ca{sup 2+}-like shell similar to liebigite [Ca{sub 2}(UO{sub 2})(CO{sub 3}){sub 3} {center_dot} 11(H{sub 2}O)] or andersonite [Na{sub 2}CaUO{sub 2}(CO{sub 3}){sub 3} {center_dot} 6H{sub 2}O]. The U precipitates are found in the form of white to light yellow cracked-formations as coatings on the dolomite gravel and as detached individual precipitates, and are associated with amorphous basalumnite [Al{sub 4}(SO{sub 4})(OH){sub 10} {center_dot} 4H{sub 2}O].

  3. Noise Exposure and Hearing Loss Among Sand and Gravel Miners

    PubMed Central

    Landen, Deborah; Wilkins, Steve; Stephenson, Mark; McWilliams, Linda

    2017-01-01

    The objectives of this study were to describe workplace noise exposures, risk factors for hearing loss, and hearing levels among sand and gravel miners, and to determine whether full shift noise exposures resulted in changes in hearing thresholds from baseline values. Sand and gravel miners (n = 317) were interviewed regarding medical history, leisure-time and occupational noise exposure, other occupational exposures, and use of hearing protection. Audiometric tests were performed both before the work shift (following a 12-hour noise-free interval) and immediately following the work shift. Full shift noise dosimetry was conducted. Miners' noise exposures exceeded the Recommended Exposure Limit (REL) of the National Institute for Occupational Safety and Health (NIOSH) for 69% of workers, and exceeded the Mine Safety and Health Administration's action level for enrollment in a hearing conservation program for 41% of workers. Significantly higher noise exposures occurred among employees of small companies, among workers with a job classification of truck driver, among males, and among black workers. Hearing protection usage was low, with 48% of subjects reporting that they never used hearing protection. Hearing impairment, as defined by NIOSH, was present among 37% of 275 subjects with valid audiograms. Black male workers and white male workers had higher hearing thresholds than males from a comparison North Carolina population unexposed to industrial noise. Small but statistically significant changes in hearing thresholds occurred following full shift noise exposure among subjects who had good hearing sensitivity at baseline. In a logistic regression model, age and history of a past noisy job were significant predictors of hearing impairment. Overall, sand and gravel workers have excessive noise exposures and significant hearing loss, and demonstrate inadequate use of hearing protection. Well-designed hearing conservation programs, with reduction of noise exposure

  4. Noise exposure and hearing loss among sand and gravel miners.

    PubMed

    Landen, Deborah; Wilkins, Steve; Stephenson, Mark; McWilliams, Linda

    2004-08-01

    The objectives of this study were to describe workplace noise exposures, risk factors for hearing loss, and hearing levels among sand and gravel miners, and to determine whether full shift noise exposures resulted in changes in hearing thresholds from baseline values. Sand and gravel miners (n = 317) were interviewed regarding medical history, leisure-time and occupational noise exposure, other occupational exposures, and use of hearing protection. Audiometric tests were performed both before the work shift (following a 12-hour noise-free interval) and immediately following the work shift. Full shift noise dosimetry was conducted. Miners' noise exposures exceeded the Recommended Exposure Limit (REL) of the National Institute for Occupational Safety and Health (NIOSH) for 69% of workers, and exceeded the Mine Safety and Health Administration's action level for enrollment in a hearing conservation program for 41% of workers. Significantly higher noise exposures occurred among employees of small companies, among workers with a job classification of truck driver, among males, and among black workers. Hearing protection usage was low, with 48% of subjects reporting that they never used hearing protection. Hearing impairment, as defined by NIOSH, was present among 37% of 275 subjects with valid audiograms. Black male workers and white male workers had higher hearing thresholds than males from a comparison North Carolina population unexposed to industrial noise. Small but statistically significant changes in hearing thresholds occurred following full shift noise exposure among subjects who had good hearing sensitivity at baseline. In a logistic regression model, age and history of a past noisy job were significant predictors of hearing impairment. Overall, sand and gravel workers have excessive noise exposures and significant hearing loss, and demonstrate inadequate use of hearing protection. Well-designed hearing conservation programs, with reduction of noise exposure

  5. Pilot-scale tests of tuff gravel flow diversion barriers for Yucca Mountain

    SciTech Connect

    Conca, J.; Apted, M.; Kessler, J.; Kessler, J.

    1995-12-31

    This project conducts pilot-scale tests on potential sand/tuff gravel barrier designs and materials by measuring their hydraulic and barrier properties for use in modeling and final designs of possible diversion barriers at Yucca Mountain. The use of rubble composed of crushed paintbrush tuff (referred to as tuff gravel) in an engineered barrier around the waste packages can provide superior performance capabilities in a geologic repository located in the vadose zone. The effectiveness of unsaturated gravel as an hydraulic barrier to inflow of water from the surrounding environment is referred to by various names, e.g., diversion barrier, capillary barrier, or Richard`s barrier. A gravel barrier can also function as a diffusion barrier to the transport of ionic contaminants away from waste packages. Preliminary studies on tuff gravel and other gravel barriers have demonstrated their performance under a wide range of conditions anticipated in disposal scenarios.

  6. Sand and gravel mine operations and reclamation planning using microcomputers

    SciTech Connect

    Ariffin, J.B.

    1990-02-01

    The purpose of this study is to focus on the application of microcomputers, also known as personal computers, in planning for sand and gravel mine operations and reclamation at a site in Story County, Iowa. This site, called the Arrasmith Pit, is operated by Martin Marietta Aggregates, Inc. The Arrasmith site, which encompasses an area of about 25 acres, is a relatively small site for aggregate mining. However, planning for the concurrent mine operation and reclamation program at this site is just as critical as with larger sites and the planning process is the same.

  7. Particulate removal processes and hydraulics of porous gravel media filters

    NASA Astrophysics Data System (ADS)

    Minto, J. M.; Phoenix, V. R.; Dorea, C. C.; Haynes, H.; Sloan, W. T.

    2013-12-01

    Sustainable urban Drainage Systems (SuDS) are rapidly gaining acceptance as a low-cost tool for treating urban runoff pollutants close to source. Road runoff water in particular requires treatment due to the presence of high levels of suspended particles and heavy metals adsorbed to these particles. The aim of this research is to elucidate the particle removal processes that occur within gravel filters that have so far been considered as 'black-box' systems. Based on these findings, a better understanding will be attained on what influences gravel filter removal efficiency and how this changes throughout their design life; leading to a more rational design of this useful technology. This has been achieved by tying together three disparate research elements: tracer residence time distribution curves of filters during clogging; 3D magnetic resonance imaging (MRI) of clogging filters and computational fluid dynamics (CFD) modelling of complex filter pore networks. This research relates column average changes in particle removal efficiency and tracer residence time distributions (RTDs) due to clogging with non-invasive measurement of the spatial variability in particle deposition. The CFD modelling provides a link between observed deposition patterns, flow velocities and wall shear stresses as well as the explanations for the change in RTD with clogging and the effect on particle transport. Results show that, as a filter clogs, particles take a longer, more tortuous path through the filter. This is offset by a reduction in filter volume resulting in higher flow velocities and more rapid particle transport. Higher velocities result in higher shear stresses and the development of preferential pathways in which the velocity exceeds the deposition threshold and the overall efficiency of the filter decreases. Initial pore geometry is linked to the pattern of deposition and subsequent formation of preferential pathways. These results shed light on the 'black-box' internal

  8. An improved method for size distribution of stream bed gravel

    USGS Publications Warehouse

    Leopold, Luna Bergere

    1970-01-01

    Random sampling of surface rocks on a gravel bar is biased toward larger sizes which, because of their area, are more likely to be picked up. Weighting can eliminate this bias. Data on average weight of a single rock are used to change numbers of rocks to weights, thus yielding size frequency data in general agreement with a sieved and weighed sample. The question of what to sample depends on the use to which the data are to be put, and is not treated in detail in this paper.

  9. A combination of gestalt therapy, Rosen Body Work, and Cranio Sacral therapy did not help in chronic whiplash-associated disorders (WAD)--results of a randomized clinical trial.

    PubMed

    Ventegodt, Søren; Merrick, Joav; Andersen, Niels Jørgen; Bendix, Tom

    2004-12-10

    The chronic state of whiplash-associated disorder (WAD) might be understood as a somatization of existential pain. Intervention aimed to improve quality of life (QOL) seemed to be a solution for such situations. The basic idea behind the intervention was holistic, restoring quality of life and relationship with self, in order to diminish tension in the locomotion system, especially the neck. A psychosomatic theory for WAD is proposed. Our treatment was a short 2-day course with teachings in philosophy of life, followed by 6-10 individual sessions in gestalt psychotherapy and body therapy (Rosen therapy and Cranio Sacral therapy), followed by a 1-day course approximately 2 months later, closing the intervention. Two independent institutions did the intervention and the assessments. In a randomized, clinically controlled setting, 87 chronic WAD patients were included with a median duration of 37 months from their whiplash accidents. One patient never started. Forty-three had the above intervention (female/male = 36/7, ages 22-49, median 37 years) and another 43 were assigned to a nontreated control group (female/male = 35/8, ages 18-48, median 38). Six had disability pension and 27 had pending medicolegal issues in each group. Effect variables were pain in neck, arm, and/or head; measures of quality of life and daily activities; as well as general physical or mental health. Wilcoxon test for between-groups comparisons with intention-to-treat analyses was conducted; the square curve paradigm testing for immediate improvements of health and quality of life was also used. The groups were comparable at baseline. From the intervention group, 11 dropped out during the intervention (4 of those later joined the follow-up investigation), 22 of the remaining 32 graduated the course, and 35 of the 43 controls did as well. Approximately 3 months later, we found no clinically relevant or significant increase in any effect measure. The above version of a quality of life

  10. Chemical fate and transport of atrazine in soil gravel materials at agrichemical distribution facilities

    USGS Publications Warehouse

    Roy, W.R.; Krapac, I.G.; Chou, S.-F.J.

    1999-01-01

    The gravel commonly used to cover parking lots and roadways at retail agrichemical facilities may contain relatively large concentrations of pesticides that resulted from past management problems. These pesticides may threaten groundwater quality. Previous studies, however, suggested that the pesticides had not moved from the gravel in several sample profiles. Excavations at a closed facility revealed tremendous variability in pesticide distribution within the site. Pesticides were present below the gravel in two profiles, but the mechanism(s) for their movement were not clear. The objectives of this study were to investigate how the physical and chemical properties of the gravel influence the environmental fate of atrazine. All of the gravel samples collected and characterized contained atrazine and sufficient organic C to adsorb significant amounts of atrazine, thus retarding its movement through the gravel. Laboratory column leaching experiments, however, suggested that much of the atrazine should leach from the gravel within a year or two. A field-scale test plot was constructed to study how atrazine moves through the gravel under controlled conditions. Atrazine was "spilled" in the test plot. Atrazine moved from the gravel both vertically and horizontally. It appears that formulated product spilled on gravel will leach. A single discrete spill can give rise to phantom spills whose occurrence and distribution is not related to any specific pesticide-management practice. The apparent lack of atrazine leaching from gravel appeared to be a transient phenomenon and/or the result of sampling limitations in previous studies. The contaminated gravel clearly poses a risk to groundwater quality.

  11. Gravel packing dual zones in one trip reduces offshore completion time

    SciTech Connect

    Brannon, D.H.; Harrison, D.T. ); van Sickle, E.W. )

    1991-09-01

    A single trip, dual-zone gravel pack system was used to successfully gravel pack two wells on Green Canyon platform 52 A in the Gulf of Mexico. An average 56 hours was saved on each well, representing reductions of about 25% in completion time and 26% in completion cost per well. Time-sensitive costs had the largest impact on Green Canyon 52 A final well completion cost; therefore, new technology or more efficient operations were required to minimize completion time. One way to enhance project economics was to gravel pack two separate zones in one trip. In this paper, four objectives are addressed during development of a single trip tool to gravel pack the stacked zones of the Marquette project. These were time and cost reduction, removal of loss circulation material (LCM) prior to gravel packing, zone isolation during gravel packing and use of conventional gravel placement techniques. The design requirement that all LCM (salt and/or viscous polymer pills), perforation debris and formation sand be removed from the wellbore prior to gravel packing was accomplished by incorporating a washdown feature that allows circulation at the bottom of the gravel pack assembly prior to landing in the sump packer.

  12. Gravel-pack field examples of a new pulsed-neutron-activation logging technique

    SciTech Connect

    Caroll, J.F.; Smith, B.C. )

    1991-12-01

    Gravel packs traditionally have been evaluated with gamma/gamma density and neutron logging tools. These logging tools, particularly the density tools, do an acceptable job in most logging environments but have some limitations that affect their measurement resolution in attempts to define gravel-pack quality. The presence of high-density completion fluids significantly reduces the dynamic range of the conventional measurements. Low-contrast logging resolution is also encountered with the new matched-density gravel-pack systems that use matrix materials with densities near those of the completion fluids. This paper presents an alternative measurement of gravel-pack quality that is unaffected by the type of completion fluid present. The authors also present six field examples that demonstrate this new technique. Each example presents a different logging condition, e.g., heavy borehole fluid in a conventional gravel pack, gravel pack with sintered bauxite, two completions with Isopac gravel of different screen sizes, and multiple gravel-pack logs recorded before and after wireline repair work. Several of these examples show that neutron activation can be a useful method of gravel-pack analysis in some logging environments.

  13. Flow resistance under conditions of intense gravel transport

    USGS Publications Warehouse

    Pitlick, John

    1992-01-01

    A study of flow resistance was undertaken in a channelized reach of the North Fork Toutle River, downstream of Mount St. Helens, Washington. Hydraulic and sediment transport data were collected in flows with velocities up to 3 m/s and shear stresses up to 7 times the critical value needed for bed load transport. Details of the flow structure as revealed in vertical velocity profiles indicate that weak bed load transport over a plane gravel bed has little effect on flow resistance. The plane gravel bed persists up to stresses ∼3 times critical, at which point, irregular bed forms appear. Bed forms greatly increase flow resistance and cause velocity profiles to become distorted. The latter arises as an effect of flows becoming depth-limited as bed form amplitude increases. At very high rates of bed load transport, an upper stage plane bed appeared. Velocity profiles measured in these flows match the law of the wall closely, with the equivalent roughness being well represented by ks = 3D84 of the bed load. The effects noted here will be important in very large floods or in rivers that are not free to widen, such as those cut into bedrock.

  14. The Persistence of Potential Refugia Mapped from Gravel Tracers

    NASA Astrophysics Data System (ADS)

    Haschenburger, J. K.

    2009-12-01

    Floods disturb aquatic habitats. On an event basis, flood characteristics control the spatial extent and depth of streambed disturbance for a given river and set limits to the amount of channel refugia for biota. The aim of this research is to quantify the area of potential refugia that persists over a long flood series and therefore affects many generations of aquatic populations. Field observations were collected in Carnation Creek, a small gravel-bed river located on the west coast of Vancouver Island, Canada. Streambed disturbance was documented by monitoring the three-dimensional positions of about 2500 magnetically tagged gravels over 277 floods. Tracer movement and burial observations were used to produce cellular maps of the frequency of bed disturbance within a GIS. The streambed exhibits different frequencies of disturbance as expected. The most active areas make up about 1% of the streambed and tend to be located near the channel thalweg. Undisturbed areas constitute more than 25% of the bed, and provide distinct areas of longer-term refugia that persist over the range of flood magnitudes observed. In addition to validating a key aspect of partial sediment transport, the results suggest that the natural variability of floods facilitates diverse aquatic communities by ensuring the availability of channel refugia over time.

  15. Sand infiltration into a gravel bed: A mathematical model

    NASA Astrophysics Data System (ADS)

    Herrero, A.; Berni, C.

    2016-11-01

    Fine sediment infiltration into a river bed is a physical process affected by different human actions and has several environmental, socioeconomic, and river morphology consequences. A theoretical model is proposed herein aiming to reproduce the fine sediment content depth profile resulting from the infiltration of fine sediment into an initially clean gravel bed. The model is based on the probability of infiltrating particles to be trapped in a pore throat formed by three bed particles. The model is tested against previous experimental results and is found to reproduce adequately the occurrence of the two infiltration mechanisms reported by previous studies: bridging and unimpeded static percolation. Theoretical depth profiles are found to underestimate fine sediment content at the bed subsurface (below 2-3 gravel diameter depth) compared to the laboratory results. This may be due to hyporheic flow that is not taken into account in our model. In flow experiments, the particles previously infiltrated and deposited might be destabilized by pore water flow and their fall down to the bed might be magnified.

  16. Plant cover and water balance in gravel admixtures at an arid waste-burial site

    SciTech Connect

    Waugh, W.J.; Thiede, M.E.; Bates, D.J.

    1994-07-01

    Isolation of radioactive waste buried in unsaturated zones will require long-term control of recharge and erosion. Soil covers control recharge at and sites by storing rainwater close enough to the surface to be removed by evapotranspiration. Surface layers of rock or gravel control erosion at sites with sparse vegetation, but can also alter plant habitat and cause recharge through interred waste. As an alternative, gravel mixed into the uppermost soil law may control erosion ever the king-term better than surface gravel layers. Gravel admixtures may also not influence plant establishment or sod water balance in waste-site covers. The interactive effects of gravel admixture concentration, vegetation, and precipitation on soil water content and plant cover were measured at the US Department of Energy`s Hanford Site. Results support use of a combination of vegetation and gravel admixtures for erosion control. Vegetation seasonally depleted root zone water storage to about 6.5 volume % regardless of precipitation amount or the presence of gravel admixture amendments. In contrast, yearly increases in soil water storage as deep as 225 cm in plots without vegetation may be a leading indicator of recharge. The composition and abundance of vegetation changed over time and with precipitation amount, but was not influenced by gravel amendments. Seeded wheatgrasses [Agropyron sibericum Wilde and Agropyron dasystachyum (Hook.) Scribn.] established only when irrigated with twice average precipitation, but persisted after the irrigation ceased. Cheatgrass (Bromus tectorum L.) and Russian thistle (Salsola kali L.) colonized areas receiving both irrigation and ambient precipitation. Stands with wheatgrasses extracted water more rapidly and depleted soil water to lower levels than cheatgrass-dominated stands. Increases in gravel cover and near-surface gravel concentrations after 5 yr were evidence of the formation of a protective gravel veneer. 44 refs., 8 figs., 2 tabs.

  17. The effect of gravel size fraction on the distribution coefficients of selected radionuclides radionuclides

    SciTech Connect

    Um, Wooyong; Serne, R. Jeffrey; Last, George V.; Glossbrenner, Ellwood T.

    2009-06-26

    This manuscript addresses the consequences of the common practice of assuming that the gravel fraction of sediments does not participate in sorption reactions and thus sorption quantified by the distribution coefficient (Kd) construct can be estimated from laboratory tests on < 2mm fraction of sediments. As shown within the use of this common assumption can lead to inaccurate estimates of the mobility and sorption capacity of key radionuclides (Tc, U, and Np) at the Hanford Site where gravel dominates the lower Hanford formation and upper Ringold Formation. Batch sorption and column experiments showed that the distribution coefficient measured using only < 2mm fraction were not in agreement with those obtained from the bulk sediments depending on the radionuclide. The least reactive radionuclide, Tc showed the lowest effects from the presence of gravel. However, differences between measured Kds using < 2mm fractions of the sediment and the Kds measured on the bulk sediment were significant for strongly reactive radionuclides such as Np, especially on the sediment with gravel fractions that contained highly reactive sites. Highly reactive sites in the gravel fraction were attributed to the presence of Fe oxides coatings and/or reactive fracture faces on the gravel surfaces. Gravel correction factors that use the sum of the Kd,<2 mm and Kd,>2 mm values to estimate the Kd for the bulk sediment were found to best describe Kds for radionuclides on the bulk sediment. However, more detailed characterization of gravel surfaces should be also conducted to identify those gravels with higher reactive sorbents, if present. Gravel correction factors should be considered to predict precisely the sorption capacity of bulk sediments that contain more than 10% gravel and to estimate the mobility of contaminants in subsurface environments.

  18. Reconnaissance of alluvial fans as potential sources of gravel aggregate, Santa Cruz River valley, Southeast Arizona

    USGS Publications Warehouse

    Lindsey, David A.; Melick, Roger

    2002-01-01

    This investigation was conducted to provide information on the aggregate potential of alluvial fan sediments in the Santa Cruz River valley. Pebble lithology, roundness, and particle size were determined in the field, and structures and textures of alluvial fan sediments were photographed and described. Additional measurements of particle size on digital photographs were made on a computer screen. Digital elevation models were acquired and compiled for viewing the areal extent of selected fans. Alluvial fan gravel in the Santa Cruz River valley reflects the lithology of its source. Gravel derived from granitic and gneissic terrane of the Tortolita, Santa Catalina, and Rincon Mountains weathers to grus and is generally inferior for use as aggregate. Gravel derived from the Tucson, Sierrita, and Tumacacori Mountains is composed mostly of angular particles of volcanic rock, much of it felsic in composition. This angular volcanic gravel should be suitable for use in asphalt but may require treatment for alkali-silica reaction prior to use in concrete. Gravel derived from the Santa Rita Mountains is of mixed plutonic (mostly granitic rocks), volcanic (mostly felsic rocks), and sedimentary (sandstone and carbonate rock) composition. The sedimentary component tends to make gravel derived from the Santa Rita Mountains slightly more rounded than other fan gravel. The coarsest (pebble, cobble, and boulder) gravel is found near the heads (proximal part) of alluvial fans. At the foot (distal part) of alluvial fans, most gravel is pebble-sized and interbedded with sand and silt. Some of the coarsest gravel was observed near the head of the Madera Canyon, Montosa Canyon, and Esperanza Wash fans. The large Cienega Creek fan, located immediately south and southeast of Tucson, consists entirely of distal-fan pebble gravel, sand, and silt.

  19. Reconnaissance of alluvial fans as potential sources of gravel aggregate, Santa Cruz River valley, Southeast Arizona

    USGS Publications Warehouse

    Lindsey, David A.; Melick, Roger

    2002-01-01

    This investigation was conducted to provide information on the aggregate potential of alluvial fan sediments in the Santa Cruz River valley. Pebble lithology, roundness, and particle size were determined in the field, and structures and textures of alluvial fan sediments were photographed and described. Additional measurements of particle size on digital photographs were made on a computer screen. Digital elevation models were acquired and compiled for viewing the areal extent of selected fans. Alluvial fan gravel in the Santa Cruz River valley reflects the lithology of its source. Gravel derived from granitic and gneissic terrane of the Tortolita, Santa Catalina, and Rincon Mountains weathers to grus and is generally inferior for use as aggregate. Gravel derived from the Tucson, Sierrita, and Tumacacori Mountains is composed mostly of angular particles of volcanic rock, much of it felsic in composition. This angular volcanic gravel should be suitable for use in asphalt but may require treatment for alkali-silica reaction prior to use in concrete. Gravel derived from the Santa Rita Mountains is of mixed plutonic (mostly granitic rocks), volcanic (mostly felsic rocks), and sedimentary (sandstone and carbonate rock) composition. The sedimentary component tends to make gravel derived from the Santa Rita Mountains slightly more rounded than other fan gravel. The coarsest (pebble, cobble, and boulder) gravel is found near the heads (proximal part) of alluvial fans. At the foot (distal part) of alluvial fans, most gravel is pebble-sized and interbedded with sand and silt. Some of the coarsest gravel was observed near the head of the Madera Canyon, Montosa Canyon, and Esperanza Wash fans. The large Cienega Creek fan, located immediately south and southeast of Tucson, consists entirely of distal-fan pebble gravel, sand, and silt.

  20. Application of Structure from Motion (SfM) Photogrammetry to Quantify Gravel Storage Following Gravel Augmentation, Oak Grove Fork of the Clackamas River, Oregon

    NASA Astrophysics Data System (ADS)

    Curran, M. L.; Hales, G.; Michalak, M.

    2016-12-01

    Digital Terrain Models (DTMs) generated in Agisoft Photoscan from photogrammetry provide a basis for a high resolution, quantitative analysis of geomorphic features that are difficult to describe using conventional, commonly used techniques. Photogrammetric analysis can be particularly useful in investigating the spatial and temporal dispersal of gravel in high gradient mountainous streams. The Oak Grove Fork (OGF), located in northwestern Oregon, is one of the largest tributaries to the Clackamas River. Lake Harriet Dam and diversion was built on the OGF in 1924 as part of a hydroelectric development by Portland General Electric. Decreased flow and sediment supply downstream of Lake Harriet Dam has resulted in geomorphic and biological changes, including reduced salmonid habitat. As part of a program to help restore a portion of the natural sediment supply and improve salmonid habitat, gravel augmentation is scheduled to begin September 2016. Tracking the downstream movement of augmented gravels is crucial to establishing program success. The OGF provides a unique setting for this study; flow is regulated at the dam, except for spillover during high flow events, and a streamflow gaging station downstream of the study area reports discharge. As such, the controlled environment of the OGF provides a natural laboratory to study how a sediment-depleted channel responds geomorphically to a known volume of added gravel. This study uses SfM to evaluate deposition of the augmented gravel following its introduction. The existing channel is characterized by coarse, angular gravel, cobble, and boulder; the augmented gravel is finer, rounded, and 5% of the volume is an exotic lithology to provide a visual tracer. Baseline, pre-gravel introduction DTMs are constructed and will be differenced with post-gravel introduction DTMs to calculate change at four study sites. Our preliminary pilot testing on another river shows that centimeter-scale accretion and aggradation within the

  1. Quantifying Stream Bed Gravel Mobility from Friction Angle Measurements

    NASA Astrophysics Data System (ADS)

    Meyers, M. A.; Dunne, T.

    2012-12-01

    A method to measure friction angles using force gauges was field tested to determine its utility at quantifying critical shear stress in a gravel bedded reach of the San Joaquin River in California. Predictions of mobility from friction angles were compared with observations of the movement of tagged particles from locations for which local shear stress was quantified with a validated 2-D flow model. The observations of movement, distance of travel, and location of the end of travel were made after extended flow releases from Friant dam. Determining the critical shear stress for gravel bed material transport currently depends upon bedload sampling or tracer studies. Often, such measurements can only be made during occasional and untimely flow events, and at limited, suboptimal locations. Yet, theoretical studies conclude that the friction angle is an important control on the critical shear stress for mobility of any grain size, and therefore of the excess shear stress which strongly influences bedload transport rate. The ability to predict bed mobility at ungauged and unmonitored locations is also an important requirement for planning of flow regimes and channel design. Therefore, a method to measure friction angles that can be performed quickly in low flow conditions would prove useful for river management and research. To investigate this promising method friction angle surveys were performed at two riffle sites where differences in bed material size and distribution, and channel slope were observed. The friction angle surveys are sensitive enough to detect differences between the sites as well as spatially and temporally within a single riffle. Low friction angles were observed along the inside of a long bend where sand content was greater (by ~20%) than other surveyed locations. Friction angles decreased slightly after a depositional event associated with transient large woody debris and bank erosion, and increased again after a 5 year return interval flow

  2. Manual for computing bed load transport using BAGS (Bedload Assessment for Gravel-bed Streams) Software

    Treesearch

    John Pitlick; Yantao Cui; Peter Wilcock

    2009-01-01

    This manual provides background information and instructions on the use of a spreadsheet-based program for Bedload Assessment in Gravel-bed Streams (BAGS). The program implements six bed load transport equations developed specifically for gravel-bed rivers. Transport capacities are calculated on the basis of field measurements of channel geometry, reach-average slope,...

  3. Simulating the role of gravel in freeze-thaw process on the Qinghai-Tibet Plateau

    NASA Astrophysics Data System (ADS)

    Pan, Yongjie; Lyu, Shihua; Li, Suosuo; Gao, Yanhong; Meng, Xianhong; Ao, Yinhuan; Wang, Shujin

    2017-02-01

    Soils containing gravel (particle size ≥2 mm) are widely distributed over the Qinghai-Tibet Plateau (QTP). Soil mixed with gravel has different thermal and hydrological properties compared with fine soil (particle size <2 mm) and thus has marked impacts on soil water and heat transfer. However, the most commonly used land models do not consider the effects of gravel. This paper reports the development of a new scheme that simulates the thermal and hydrological processes in soil containing gravel and its application in the QTP. The new scheme was implemented in version 4 of the Community Land Model, and experiments were conducted for two typical sites in the QTP. The results showed that (1) soil with gravel tends to reduce the water holding capacity and enhance the hydraulic conductivity and drainage; (2) the thermal conductivity increases with soil gravel content, and the response of the temperature of soil mixed with gravel to air temperature change is rapid; (3) the new scheme performs well in simulating the soil temperature and moisture—the mean biases of soil moisture between the simulation and observation reduced by 25-48 %, and the mean biases of soil temperature reduced by 9-25 %. Therefore, this scheme can successfully simulate the thermal and hydrological processes in soil with different levels of gravel content and is potentially applicable in land surface models.

  4. Evaluation of an ion adsorption method to estimate intragravel flow velocity in salmonid spawning gravels

    Treesearch

    James L. Clayton; John G. King; Russell F. Thurow

    1996-01-01

    Intragravel water exchange provides oxygenated water, removes metabolic waste, and is an essential factor in salmonid embryo survival. Measurements of intragravel flow velocity have been suggested as an index of gravel quality and also as a useful predictor of fry emergence; however, proposed methods for measuring velocity in gravel are problematic. We evaluate an ion...

  5. Prediction of sand transport over immobile gravel from supply limited to capacity conditions

    USDA-ARS?s Scientific Manuscript database

    Prediction of the transport of sand in channels armored with gravel downstream of dams is difficult but necessary for the range of bed conditions from supply limited to capacity transport. Previous work has shown that information on the mean elevation of the sand relative to the gravel and on the s...

  6. PROFILE: Hungry Water: Effects of Dams and Gravel Mining on River Channels

    PubMed

    Kondolf

    1997-07-01

    / Rivers transport sediment from eroding uplands to depositional areas near sea level. If the continuity of sediment transport is interrupted by dams or removal of sediment from the channel by gravel mining, the flow may become sediment-starved (hungry water) and prone to erode the channel bed and banks, producing channel incision (downcutting), coarsening of bed material, and loss of spawning gravels for salmon and trout (as smaller gravels are transported without replacement from upstream). Gravel is artificially added to the River Rhine to prevent further incision and to many other rivers in attempts to restore spawning habitat. It is possible to pass incoming sediment through some small reservoirs, thereby maintaining the continuity of sediment transport through the system. Damming and mining have reduced sediment delivery from rivers to many coastal areas, leading to accelerated beach erosion. Sand and gravel are mined for construction aggregate from river channel and floodplains. In-channel mining commonly causes incision, which may propagate up- and downstream of the mine, undermining bridges, inducing channel instability, and lowering alluvial water tables. Floodplain gravel pits have the potential to become wildlife habitat upon reclamation, but may be captured by the active channel and thereby become instream pits. Management of sand and gravel in rivers must be done on a regional basis, restoring the continuity of sediment transport where possible and encouraging alternatives to river-derived aggregate sources.KEY WORDS: Dams; Aquatic habitat; Sediment transport; Erosion; Sedimentation; Gravel mining

  7. A general power equation for predicting bed load transport rates in gravel bed rivers

    Treesearch

    Jeffrey J. Barry; John M. Buffington; John G. King

    2004-01-01

    A variety of formulae has been developed to predict bed load transport in gravel bed rivers, ranging from simple regressions to complex multiparameter formulations. The ability to test these formulae across numerous field sites has, until recently, been hampered by a paucity of bed load transport data for gravel bed rivers. We use 2104 bed load transport observations...

  8. Partial transport in a natural gravel bed channel

    NASA Astrophysics Data System (ADS)

    Haschenburger, Judith K.; Wilcock, Peter R.

    2003-01-01

    Partial transport is documented in the gravel bed channel of Carnation Creek using magnetically tagged stones. For four flood peaks the active proportion of surface grains was used to map streambed areas into distinct units of three different levels of grain entrainment. In partially mobile regions of the bed, the active proportion of surface grains declines with grain size. As flow increases, areas of partial transport grow at the expense of inactive areas and fully active areas replace areas with partial mobility. Approximately 25-50% of the bed remained in a state of partial mobility during a flood with a 2-year return period, indicating that inactive regions of the bed surface typically persist from year to year. During a flood with a 7-year return period, surface grain entrainment was nearly complete, indicating that full mobilization of surface grains is not a frequent event.

  9. Injury experience in sand and gravel mining, 1991

    SciTech Connect

    Not Available

    1993-10-01

    This Mine Safety and Health Administration (MSHA) informational report reviews in detail the occupational injury and illness experience of sand and gravel mining in the United States for 1991. Data reported by operators of mining establishments concerning work injuries are summarized by work location, accident classification, part of body injured, nature of injury, and occupation. Related information on employment, worktime, and operating activity also is presented. Data reported by independent contractors performing certain work at mining locations are depicted separately in this report. For ease of comparison with other metal and nonmetallic mineral mining industries and with coal mining, summary reference tabulations are included at the end of both the operator and the contractor sections of this report.

  10. Monitoring and analysis of gravel-packing procedures to explain well performance

    SciTech Connect

    McLeod, H.O. Jr. ); Minarovic, M.J. )

    1994-10-01

    Gravel-packed gas wells completed in the Gulf of Mexico since 1980 were reviewed to build a selective database for a completion-effectiveness study. Gas wells with clean, uniform sands were selected for analysis. Significant monitoring data identified were injectivity tests at different points during the completion and fluid loss rates (barrels per hour). Injectivity before gravel packing and productivity after gravel packing were classified according to sidewall-core permeabilities. Different gravel-pack preparation and execution techniques were reviewed. Fluid-loss-control pills were identified as the greatest source of damage restricting gravel-packed well productivity. Injectivity tests and sidewall-core permeabilities provide valuable information for monitoring well completion procedures.

  11. The model test of restoration project of the gravel beach of Chen Village fishing port

    NASA Astrophysics Data System (ADS)

    Wang, D. X.; Gui, J. S.; Sun, J. W.

    2016-08-01

    Gravel beach is a case in coastal landform by wave action. It is more and more crucial for the environment of coastal engineering in recent years. However, it is poorly studied for it in China. And this paper which is based on the model test of Restoration Project of the Gravel Beach of Chen Village Fishing Port, uses two dimensional normal physical models, aiming at exploring the movement of gravel beach under wave action and verifying the stability of the gravel beach section. The test depends on different water levels (designed high water level, designed low water level, and extreme high water level) and return periods (2, 5, 10, 25, 50 years once). Finally, two distinct experimental sections are got under the changed conditions and the movement law of gravels is obtained.

  12. Diffusion And Flow In Gravel, Soil, And Whole Rock

    NASA Astrophysics Data System (ADS)

    Conca, James L.; Wright, Judith

    1992-01-01

    Transport parameters (diffusion coefficients, D(θ), hydraulic conductivities, K(θ), and retardation factors, Rf were experimentally determined in unsaturated soil, gravel, bentonite, and whole rock over a wide range of water contents, fixed at desired levels using the Unsaturated Flow Apparatus (UFATM). Effective diffusion coefficients in all media were found primarily to be a function of volumeric water cintent (θ) and not material characteristics, except where the characteristics affect or determine water content. At high water contents, D(θ) gradually declines as water content decreases, from 10-5cm2/s at a θ of about 50% to 10-7cm2/s at a θ of about 5%, followed by a sharp decline as surface films become thin and discontinuous, and pendular water elements become very small, from 10-7cm2/s at a θ of about 5% to 10-10cm2/s at a θ of about 0,5%. The several whole rock cores studied behaved similary. In aggregate material such as gravel and soil where the particles themselves have significant porosity, only the surface water content, not the internal water of the particles, contributes to the diffusion coefficient and hydraulic conductivity under unsaturated conditions, although the internal water is very important in retardation and other chemical effects. Experimentally determined K(θ) compares favorably to van Genuchten/Mualem relationships calculated from laboratory-determined water retention versus matric potential data obtained on the same soils. Experimentally determined K(θ) for whole rock appears to validate capillary bundle theory.

  13. Sedimentology of Martian Gravels from Mardi Twilight Imaging: Techniques

    NASA Technical Reports Server (NTRS)

    Garvin, James B.; Malin, Michael C.; Minitti, M. E.

    2014-01-01

    Quantitative sedimentologic analysis of gravel surfaces dominated by pebble-sized clasts has been employed in an effort to untangle aspects of the provenance of surface sediments on Mars using Curiosity's MARDI nadir-viewing camera operated at twilight Images have been systematically acquired since sol 310 providing a representative sample of gravel-covered surfaces since the rover departed the Shaler region. The MARDI Twilight imaging dataset offers approximately 1 millimeter spatial resolution (slightly out of focus) for patches beneath the rover that cover just under 1 m2 in area, under illumination that makes clast size and inter-clast spacing analysis relatively straightforward using semi- automated codes developed for use with nadir images. Twilight images are utilized for these analyses in order to reduce light scattering off dust deposited on the front MARDI lens element during the terminal stages of Curiosity's entry, descent and landing. Such scattering is worse when imaging bright, directly-illuminated surfaces; twilight imaging times yield diffusely-illuminated surfaces that improve the clarity of the resulting MARDI product. Twilight images are obtained between 10-30 minutes after local sunset, governed by the timing of the end of the no-heat window for the camera. Techniques were also utilized to examine data terrestrial locations (the Kau Desert in Hawaii and near Askja Caldera in Iceland). Methods employed include log hyperbolic size distribution (LHD) analysis and Delauney Triangulation (DT) inter-clast spacing analysis. This work extends the initial results reported in Yingst et al., that covered the initial landing zone, to the Rapid-Transit Route (RTR) towards Mount Sharp.

  14. Bulk Friction Angles in Dry, Drained, and Saturated Gravel Beds

    NASA Astrophysics Data System (ADS)

    Holo, S.; Palucis, M. C.; Lamb, M. P.

    2015-12-01

    We examined the effect of capillary action and lubrication of grains on bulk friction angles through tilting chute experiments. In each experiment, we screed a bed of 5mm gravels in 65cm long x 18cm wide tilting chute with fixed roughness and slowly tilted the chute until a granular avalanche occurred. We performed these experiments under three conditions: with dry grains, with a bed that had been submerged and subsequently drained such that no water occupied the pore space, and with the entire apparatus submerged under water such that the bed is saturated. In addition, for each of these cases, we performed experiments with 5, 10, and 15cm bed thicknesses. In the dry case, the bed failed at ~ 41º, and bed thickness did not have a significant effect on failure angle. In the drained case, friction angles increased from 46.5º to 50.9º with increasing bed thickness. In the submerged case, the bed failed at angles not significantly different than those from the dry case, and they did not vary with bed thickness. The increase in friction angles between the dry and drained cases suggests that addition of the water induces a cohesive effect on the grains. Because the pore pressure from the saturated bed removes capillary effects but retains lubrication effects, the submerged case data suggest that capillary action is primarily responsible for the observed increases in friction angle and effects from grain lubrication are negligible. Further study is ongoing to fully understand the effect of capillary action on bulk friction angles in unsaturated gravel and why it appears to increase with bed thickness.

  15. Bedload pulses in a hydropower affected alpine gravel bed river

    NASA Astrophysics Data System (ADS)

    Aigner, Johann; Kreisler, Andrea; Rindler, Rolf; Hauer, Christoph; Habersack, Helmut

    2017-08-01

    This study investigated the sediment resupply and transport dynamics at the Upper Drau River upstream of Lienz (Eastern Tyrol, Austria). Due to a hydropower plant, a 24 km long river reach of this alpine gravel bed river is under residual flow conditions, although sediment is still resupplied into the reach through many active torrents and tributaries. As a result, sediment deposition in the residual flow reach intensified, hence increasing maintenance efforts to stabilize this river section and ensure flood protection. In combination with a new sediment management program, a continuous bedload monitoring system was installed 2 km downstream of the residual reach in 2001 to support the development of adapted sediment management strategies. The surrogate bedload monitoring system consists of 16 impact plate geophones, installed over a 17 m wide cross section. The unprecedented 15-year dataset of high-resolution bedload intensity revealed a complex process of gravel storage and intermittent resupply from the residual reach, allowing the authors a detailed analysis of frequently occurring bedload pulses. These transport features are triggered by increased discharges during floods in the residual reach and created pronounced anticlockwise bedload hysteresis or, with a temporal shift to the event peak, caused distinct shifts in the bedload activity downstream. Bedload pulses produce very high bedload fluxes while in transit, tend to increase bedload flux in the post-event phase, and can alter and reduce the upstream sediment storage leading to a lowering of bedload availability for future pulses. The observed time lags between main discharge events and the arrival of the macro-pulses are correlated with mean water discharge during pulse propagation, thus enabling a prediction of the pulse arrival at the monitoring station solely based on the hydrograph. In combination with the hydrological setup of the reach, the observed bedload pulse time lags allowed an estimation of

  16. Wind-formed gravel bed forms, Wright Valley, Antarctica

    NASA Astrophysics Data System (ADS)

    Gillies, John A.; Nickling, William G.; Tilson, Michael; Furtak-Cole, Eden

    2012-12-01

    Bed forms composed of gravel size particles (≈50% of particles >4 mm) are observed in the Wright Valley of the McMurdo Dry Valley system in Antarctica. These bed forms are characterized by a very asymmetrical shape with a mean aspect ratio of 0.025 (standard deviation 0.005), mean wavelength of 2.7 m (±0.49 m), and a mean height of 0.06 m (±0.01 m). Particle size analysis of the bed form sediments shows bimodality with a peak near 9 mm and another between 0.5 mm and 0.25 mm. Time-integrated sediment trap samples of horizontal saltation and creep flux indicate the flux of particles ≥4 mm during the two-year monitoring period was extremely low. Measurements of the horizontal displacement of tracer particles (14 mm, 12 mm, 10 mm, 8 mm, and 6 mm diameter) placed onto the bed forms corroborate the low particle flux measurements and limited movement of particles. The bed forms share form and grain size characteristics with both ripples and mega-ripples, showing poor sorting of particles across a single wavelength except for a slight coarsening at the crest similar to ripples, but their sinuosity suggest that transverse instabilities affect their formation similar to mega-ripples. Based on the data for the prevailing environmental conditions it can be argued that the Wright Valley form is an expression of gravel particles moved solely by highly intermittent creep processes. This also argues for the need for a very long period of time for their evolution, on the order of centuries.

  17. The Effectiveness of Conservative Management for Acute Whiplash Associated Disorder (WAD) II: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

    PubMed Central

    Wiangkham, Taweewat; Duda, Joan; Haque, Sayeed; Madi, Mohammad; Rushton, Alison

    2015-01-01

    Objective To evaluate the effectiveness of conservative management (except drug therapy) for acute Whiplash Associated Disorder (WAD) II. Design Systematic review and meta-analysis of Randomised Controlled Trials (RCTs) using a pre-defined protocol. Two independent reviewers searched information sources, decided eligibility of studies, and assessed risk of bias (RoB) of included trials. Data were extracted by one reviewer and checked by the other. A third reviewer mediated any disagreements throughout. Qualitative trial and RoB data were summarised descriptively. Quantitative syntheses were conducted across trials for comparable interventions, outcome measures and assessment points. Meta-analyses compared effect sizes with random effects, using STATA version 12. Data Sources PEDro, Medline, Embase, AMED, CINAHL, PsycINFO, and Cochrane Library with manual searching in key journals, reference lists, British National Bibliography for Report Literature, Center for International Rehabilitation Research Information & Exchange, and National Technical Information Service were searched from inception to 15th April 2015. Active researchers in the field were contacted to determine relevant studies. Eligibility Criteria for Selecting Studies RCTs evaluating acute (<4 weeks) WADII, any conservative intervention, with outcome measures important to the International Classification of Function, Disability and Health. Results Fifteen RCTs all assessed as high RoB (n=1676 participants) across 9 countries were included. Meta-analyses enabled 4 intervention comparisons: conservative versus standard/control, active versus passive, behavioural versus standard/control, and early versus late. Conservative intervention was more effective for pain reduction at 6 months (95%CI: -20.14 to -3.38) and 1-3 years (-25.44 to -3.19), and improvement in cervical mobility in the horizontal plane at <3 months (0.43 to 5.60) compared with standard/control intervention. Active intervention was effective

  18. Modeling the soil water retention curves of soil-gravel mixtures with regression method on the Loess Plateau of China.

    PubMed

    Wang, Huifang; Xiao, Bo; Wang, Mingyu; Shao, Ming'an

    2013-01-01

    Soil water retention parameters are critical to quantify flow and solute transport in vadose zone, while the presence of rock fragments remarkably increases their variability. Therefore a novel method for determining water retention parameters of soil-gravel mixtures is required. The procedure to generate such a model is based firstly on the determination of the quantitative relationship between the content of rock fragments and the effective saturation of soil-gravel mixtures, and then on the integration of this relationship with former analytical equations of water retention curves (WRCs). In order to find such relationships, laboratory experiments were conducted to determine WRCs of soil-gravel mixtures obtained with a clay loam soil mixed with shale clasts or pebbles in three size groups with various gravel contents. Data showed that the effective saturation of the soil-gravel mixtures with the same kind of gravels within one size group had a linear relation with gravel contents, and had a power relation with the bulk density of samples at any pressure head. Revised formulas for water retention properties of the soil-gravel mixtures are proposed to establish the water retention curved surface models of the power-linear functions and power functions. The analysis of the parameters obtained by regression and validation of the empirical models showed that they were acceptable by using either the measured data of separate gravel size group or those of all the three gravel size groups having a large size range. Furthermore, the regression parameters of the curved surfaces for the soil-gravel mixtures with a large range of gravel content could be determined from the water retention data of the soil-gravel mixtures with two representative gravel contents or bulk densities. Such revised water retention models are potentially applicable in regional or large scale field investigations of significantly heterogeneous media, where various gravel sizes and different gravel

  19. Modeling the Soil Water Retention Curves of Soil-Gravel Mixtures with Regression Method on the Loess Plateau of China

    PubMed Central

    Wang, Huifang; Xiao, Bo; Wang, Mingyu; Shao, Ming'an

    2013-01-01

    Soil water retention parameters are critical to quantify flow and solute transport in vadose zone, while the presence of rock fragments remarkably increases their variability. Therefore a novel method for determining water retention parameters of soil-gravel mixtures is required. The procedure to generate such a model is based firstly on the determination of the quantitative relationship between the content of rock fragments and the effective saturation of soil-gravel mixtures, and then on the integration of this relationship with former analytical equations of water retention curves (WRCs). In order to find such relationships, laboratory experiments were conducted to determine WRCs of soil-gravel mixtures obtained with a clay loam soil mixed with shale clasts or pebbles in three size groups with various gravel contents. Data showed that the effective saturation of the soil-gravel mixtures with the same kind of gravels within one size group had a linear relation with gravel contents, and had a power relation with the bulk density of samples at any pressure head. Revised formulas for water retention properties of the soil-gravel mixtures are proposed to establish the water retention curved surface models of the power-linear functions and power functions. The analysis of the parameters obtained by regression and validation of the empirical models showed that they were acceptable by using either the measured data of separate gravel size group or those of all the three gravel size groups having a large size range. Furthermore, the regression parameters of the curved surfaces for the soil-gravel mixtures with a large range of gravel content could be determined from the water retention data of the soil-gravel mixtures with two representative gravel contents or bulk densities. Such revised water retention models are potentially applicable in regional or large scale field investigations of significantly heterogeneous media, where various gravel sizes and different gravel

  20. Convulxin, a C-type lectin-like protein, inhibits HCASMCs functions via WAD-motif/integrin-αv interaction and NF-κB-independent gene suppression of GRO and IL-8.

    PubMed

    Shih, Chun-Ho; Chiang, Tin-Bin; Wang, Wen-Jeng

    2017-03-15

    Convulxin (CVX), a C-type lectin-like protein (CLPs), is a potent platelet aggregation inducer. To evaluate its potential applications in angiogenic diseases, the multimeric CVX were further explored on its mode of actions toward human coronary artery smooth muscle cells (HCASMCs). The N-terminus of β-chain of CVX (CVX-β) contains a putative disintegrin-like domain with a conserved motif upon the sequence comparison with other CLPs. Importantly, native CVX had no cytotoxic activity as examined by electrophoretic pattern. A Trp-Ala-Asp (WAD)-containing octapeptide, MTWADAEK, was thereafter synthesized and analyzed in functional assays. In the case of specific integrin antagonists as positive controls, the anti-angiogenic effects of CVX on HCASMCs were investigated by series of functional analyses. CVX showed to exhibit multiple inhibitory activities toward HCASMCs proliferation, adhesion and invasion with a dose- and integrin αvβ3-dependent fashion. However, the WAD-octapeptide exerting a minor potency could also work as an active peptidomimetic. In addition, flow cytometric analysis demonstrated both the intact CVX and synthetic peptide can specifically interact with integrin-αv on HCASMCs and CVX was shown to have a down-regulatory effect on the gene expression of CXC-chemokines, such as growth-related oncogene and interleukin-8. According to nuclear factor-κB (NF-κB) p65 translocation assay and Western blotting analysis, the NF-κB activation was not involved in the signaling events of CVX-induced gene expression. In conclusion, CVX may act as a disintegrin-like protein via the interactions of WAD-motif in CVX-β with integrin-αv on HCASMCs and it also is a gene suppressor with the ability to diminish the expression of two CXC-chemokines in a NF-κB-independent manner. Indeed, more extensive investigations are needed and might create a new avenue for the development of a novel angiostatic agent.

  1. Evolution of coarse gravel bed forms; field measurements at flood stage

    USGS Publications Warehouse

    Dinehart, Randy L.

    1992-01-01

    Field measurements to investigate the origin and growth of mesoscale gravel bed forms in deep flows were made in the North Fork Toutle River, Washington. Sonar observations of the gravel streambed at a stationary point were recorded during two storm flows in December 1989 and January 1990 with concurrent bed load sampling and continuous velocity measurements. Mean diameter of bed load was about 3 cm, flow depths were 1.4–2.4 m, and bed shear stresses were 2–5 times the critical stress of mean bed load diameter, as computed from the depth-slope product. These records document the hydrodynamic conditions under which dunelike coarse gravel bed forms were observed. Coarse gravel dunes (height, 20 cm; length, 6–15 m) evolved more than 24 hours after peak stage, primarily by accretion, as inferred from bed form changes revealed in dual sonar records. Dune heights increased to 40 cm as mean trough elevation rose about 50 cm over several hours. Smaller dunes (wavelength, 1–3 m), transitional from bed load sheets, migrated on the backs of the large dunes. The superposed dunes finally became indistinguishable from the large dunes, which diminished in height by increasing the mean level of troughs. Gravel deposition occurred at the observation point in conjunction with migration of gravel dunes. The direct comparison of known bed form regimes and gravel bar facies provides alternative interpretations of gravelly deposits.

  2. Hungry water: Effects of dams and gravel mining on river channels

    SciTech Connect

    Kondolf, G.M.

    1997-07-01

    Rivers transport sediment from eroding uplands to depositional areas near sea level. If the continuity of sediment transport is interrupted by dams or removal of sediment from the channel by gravel mining, the flow may become sediment-starved (hungry water) and prone to erode the channel bed and banks, producing channel incision (downcutting), coarsening of bed material, and loss of spawning gravels for salmon and trout (as smaller gravels are transported without replacement from upstream), Gravel is artificially added to the River Rhine to prevent further incision and to many other rivers in attempts to restore spawning habitat. It is possible to pass incoming sediment through some small reservoirs, thereby maintaining the continuity of sediment transport through the system. Damming and mining have reduced sediment delivery from rivers to many coastal areas, leading to accelerated beach erosion. Sand and gravel are mined for construction aggregate from river channel and floodplains. In-channel mining commonly causes incision, which may propagate up- and downstream of the mine, undermining bridges, inducing channel instability, and lowering alluvial water tables. Floodplain gravel pits have the potential to become wildlife habitat upon reclamation, but may be captured by the active channel and thereby become instream pits. Management of sand and gravel in rivers must be done on a regional basis, restoring the continuity of sediment transport where possible and encouraging alternatives to river-derived aggregate sources. 80 refs., 17 figs.

  3. On the structure of turbulent gravel bed flow: Implications for sediment transport

    NASA Astrophysics Data System (ADS)

    Mohajeri, Seyed Hossein; Righetti, Maurizio; Wharton, Geraldene; Romano, Giovanni Paolo

    2016-06-01

    The main objective of this study was to examine the turbulent flow field over gravel particles as a first step towards understanding sediment transport in a gravel bed river. Specifically, the vertical momentum flux in gravel bed turbulent flow was investigated with particular attention to the near-bed region. Spatial organization of vertical momentum flux was studied with stereoscopic Particle Image Velocimetry (PIV) measurements in a horizontal layer 1mm above the gravel crests. The vertical momentum flux through the water column was described with digital PIV measurements in three vertical planes. The data showed that near the gravel bed, net turbulent momentum flux spatially varies with respect to bed topography. Analysis of the vertical velocity data revealed that near the gravel particle crests, there is a significant net vertical form-induced momentum flux approximately with the same order of magnitude as the net vertical turbulent momentum flux. Above the crests, total net vertical momentum flux is positive. However, below the crests, despite noticeable positive form-induced momentum flux, total net vertical momentum flux is negative. Results of quadrant analysis show that variation of turbulent net vertical momentum flux through water column is in agreement with prevalence of upward movement of low velocity flow (known as ejection) above gravel crests and downward movement of high velocity flow (known as sweep) below gravel crests. Below gravel crests (- 0.1 < z / H < 0.0), there is a region where the contribution of second quadrant to Reynolds shear stress is lower than fourth quadrant, while the contribution of second quadrant to vertical momentum flux is higher than fourth quadrant. This can be interpreted that ejection events in this region are strong enough to lift up fine particles but their contribution is not sufficient to move fine particles in the longitudinal direction.

  4. Distribution of uranium and thorium in dolomitic gravel fill and shale saprolite.

    PubMed

    Phillips, D H; Watson, D B

    2015-03-21

    The objectives of this study were to examine (1) the distribution of U and Th in dolomitic gravel fill and shale saprolite, and (2) the removal of uranium from acidic groundwater by dolomitic gravel through precipitation with amorphous basaluminite at the U.S. DOE Oak Ridge Integrated Field Research Challenge (ORIFRC) field site west of the Oak Ridge Y-12 National Security Complex in East Tennessee. Media reactivity and sustainability are a technical concern with the deployment of any subsurface reactive media. Because the gravel was placed in the subsurface and exposed to contaminated groundwater for over 20 years, it provided a unique opportunity to study the solid and water phase geochemical conditions within the media after this length of exposure. This study illustrates that dolomite gravel can remove U from acidic contaminated groundwater with high levels of Al(3+), Ca(2+), NO(3-), and SO4(2-) over the long term. As the groundwater flows through high pH carbonate gravel, U containing amorphous basaluminite precipitates as the pH increases. This is due to an increase in groundwater pH from 3.2 to ∼6.5 as it comes in contact with the gravel. Therefore, carbonate gravel could be considered as a possible treatment medium for removal and sequestration of U and other pH sensitive metals from acidic contaminated groundwater. Thorium concentrations are also high in the carbonate gravel. Thorium generally shows an inverse relationship with U from the surface down into the deeper saprolite. Barite precipitated in the shallow saprolite directly below the dolomitic gravel from barium present in the acidic contaminated groundwater.

  5. Use of GPR technique in surveying gravel road wearing course

    NASA Astrophysics Data System (ADS)

    Saarenketo, Timo; Vesa, Heikki

    2000-04-01

    During summer 1998 a series of tests were conducted in Finland in order to find out how Ground Penetrating Radar (GPR) technology can be utilized at both the project and network level, when surveying the wearing course thickness of gravel roads. The second objective was to investigate the possibilities of applying dielectricity information obtained using the GPR surface reflection method when determining the quality of the gravel road wearing course. In this study GPR was tested at the project level on highway 9241 Simo in Northern Finland, where the information provided by the GPR and laboratory research was used in designing and proportioning a new wearing course. In the network level studies, performed in the maintenance areas of Kemi and Karstula in Northern and Central Finland the goal for using GPR was to inspect the condition and thickness of the wearing course and evaluate the need for additional wearing course material. The total length of the roads under survey was approximately 200 km and both a 1.5 GHz ground-coupled antenna and a 1.0 GHz horn antenna were tested in this study. The research results show that GPR can be used to measure the thickness of the wearing course, the average measuring error against reference drilling measurements being 25 mm, which is considerably larger than the error of radar measurements in paved roads. To a great extent this is due to the fact that the thickness of the wearing course varies greatly even in the road's cross-section and thus a single reference thickness does not represent the actual thickness of the area measured with the GPR. The wearing course can often get mixed up with lower layers, which makes it difficult to determine the exact layer interfaces. For this reason reference information must always be used along with the GPR measurement results. Of the two GPR antennae tested, the horn antenna proved to be the more effective in measurements. The dielectric value of the wearing course, measured using the horn

  6. Streamwise decrease of the 'unsteady' virtual velocity of gravel tracers

    NASA Astrophysics Data System (ADS)

    Klösch, Mario; Gmeiner, Philipp; Habersack, Helmut

    2017-04-01

    Gravel tracers are usually inserted and transported on top of the riverbed, before they disperse vertically and laterally due to periods of intense bedload, the passage of bed forms, lateral channel migration and storage on bars. Buried grains have a lower probability of entrainment, resulting in a reduction of overall mobility, and, on average, in a deceleration of the particles with distance downstream. As a consequence, the results derived from tracer experiments and their significance for gravel transport may depend on the time scale of the investigation period, complicating the comparison of results from different experiments. We developed a regression method, which establishes a direct link between the transport velocity and the unsteady flow variables to yield an 'unsteady' virtual velocity, while considering the tracer slowdown with distance downstream in the regression. For that purpose, the two parameters of a linear excess shear velocity formula (the critical shear velocity u*c and coefficient a) were defined as functions of the travelled distance since the tracer's insertion. Application to published RFID tracer data from the Mameyes River, Puerto Rico, showed that during the investigation period the critical shear velocity u*c of tracers representing the median bed particle diameter (0.11 m) increased from 0.36 m s-1 to 0.44 m s-1, while the coefficient a decreased from the dimensionless value of 4.22 to 3.53, suggesting a reduction of the unsteady virtual velocity at the highest shear velocity in the investigation period from 0.40 m s-1 to 0.08 m s-1. Consideration of the tracer slowdown improved the root mean square error of the calculated mean displacements of the median bed particle diameter from 8.82 m to 0.34 m. As in previous work these results suggest the need of considering the history of transport when deriving travel distances and travel velocities, depending on the aim of the tracer study. The introduced method now allows estimating the

  7. Paleohydrology of the eocene ballena gravels, San Diego County, California

    NASA Astrophysics Data System (ADS)

    Steer, Bradley L.; Abbott, Patrick L.

    1984-03-01

    The Ballena Gravels are remnants of a river system that flowed westward across the ancestral Peninsular Ranges during medial and late Eocene time. The Gravels (actually conglomerate) are channelized fluvial deposits that built westward as alluvial fan (Poway Group), submarine canyon (Scripps Formation) and submarine fan (Jolla Vieja Formation) depositional systems. Because the integrated sedimentary system contains distinctive Poway rhyolite clasts of limited geographic and temporal extent the now separated component formations are recognizable on the San Diego coastal plain and on the Channel Islands. Paleogeographic reconstructions suggest a transport distance of about 315 km. Multiple techniques analysis suggests the channel gradient in the San Diego area was 12-18 m km -1. Stream velocity, based on a competent particle size of 52 cm, ranges from 2.5 to 4 m s -1. Eight equations based on slope and velocity generated estimates of channel depth at food stage that vary from 2.5 to 4.5 m. Paleodischarge can be estimated from regime-type engineering equations that are based on gradient, depth, and grain size. Paleodischarge also is calculated using a technique based on stream length and drainage area. Values generated by multiple techniques suggest 2.33-yr flood discharges of about 275 m 3 s -1. Extrapolation based on a logarithmic curve indicates 100-yr flood discharges around 27,500 m 3 s -1. Channel-width estimates for 1 to 2.33 yr floods range from 25 to 75 m. Calculations of seasonally dominant rainfall, based on runoff and temperature, vary between 50-75 cm annually. Runoff is estimated from discharge values and paleotemperatures are based on caliche type, salt-fractured clasts, and the immature clay mineral suite. The Nueces River of Texas shares some of the same characteristics of the Eocene Ballena river. The Nueces has a highly varied discharge due to seasonally intense rainfall similar to that interpreted for the Ballena river. Several rivers flowing to

  8. Assessment of the sand and gravel resources of the Lower Boise River Valley area, Idaho: part one: geological framework of the sand and gravel deposits

    USGS Publications Warehouse

    Bliss, James D.; Moyle, Phillip R.

    2001-01-01

    The USGS has undertaken a first order evaluation of sand & gravel resources in the Lower Boise River Valley in response to rapid urban expansion in the Boise-Nampa-Caldwell corridor in southwest Idaho. The study is intended to provide land-use planners and managers, particularly in the Bureau of Land Management, with a foundation of knowledge that will allow them to anticipate and plan for demand for and development of sand and gravel resources on public lands in response to the urban growth. Attributes under study include: regional geology of both alluvial source areas as well as deposits; fluvial processes that led to deposition of the sand and gravel deposits; spatial distribution of the deposits; quantity and quality of materials in the deposits; and the suitability of the deposits for a range of applications. The study will also examine and attempt to model the association between fluvial processes, deposit characteristics, and physical specifications for various applications of sand and gravel. The results will be presented in a series of sand and gravel assessment reports of which this is the first.

  9. [Genetic characterization of the Wad Medani virus (WMV) (Reoviridae, Orbivirus), isolated from the ticks Hyalomma asiaticum Schulze et Schlottke, 1930 (Ixodidae: Hyalomminae) in Turkmenistan, Kazakhstan, and Armenia and from the ticks H. anatolicum Koch, 1844 in Tajikistan].

    PubMed

    Al'khovskiĭ, S V; L'vov, D K; Shchelkanov, M Iu; Shchetinin, A M; Deriabin, P G; Gitel'man, A K; Aristova, V A; Botikov, A G

    2014-01-01

    Near full-genome sequence of the Wad Medani Virus (WMV) (strain LEIV-8066Tur) (Orbivirus, Reoviridae) isolated from the ticks Hyalomma asiaticum Schulze et Schlottke, 1929, collected from sheep in Baharly district in Turkmenistan, was determined using next generation sequencing approach. The similarity of the RNA-dependent RNA-polymerase (Pol, VP1) amino acid sequence between WMV and the Kemerovo group orbiviruses (KEMV), as well as of the Baku virus (BAKV), was 64%. The similarity of the conserved structural protein VP3 (T2) of WMV with mosquito-borne and tick-borne orbiviruses reaches 46% and 67%, respectively. For the surface proteins VP2, VP5, and VP7 (T13), which have major antigenic determinants of orbiviruses, the similarity of WMV with tickborne orbiviruses (KEMV and BAKV) is 26-30%, 45% and, 57%, respectively (ID GenBank: KJ425426-35).

  10. Tertiary gold-bearing channel gravel in northern Nevada County, California

    USGS Publications Warehouse

    Peterson, D.W.; Yeend, W.E.; Oliver, H.W.; Mattick, R.E.

    1968-01-01

    The remains of a huge Tertiary gravel-filled channel lie in the area between the South and Middle Yuba Rivers in northern Nevada County, Calif. The deposits in this channel were the site of some of the most productive hydraulic gold mines in California between the 1850's and 1884. The gravel occupies a major channel and parts of several tributaries that in Tertiary time cut into a surface of Paleozoic and Mesozoic igneous and metamorphic rocks. The gravel is partly covered by the remains of an extensive sheet of volcanic rocks, but it crops out along the broad crest of the ridge between the canyons of the South and Middle Yuba Rivers. The lower parts of the gravel deposits generally carry the highest values of placer gold. Traditionally, the richest deposits of all are found in the so-called blue gravel, which, when present, lies just above the bedrock and consists of a very coarse, poorly sorted mixture of cobbles, pebbles, sand, and clay. It is unoxidized, and, at least locally, contains appreciable quantities of secondary sulfide minerals, chiefly pyrite. Information in drill logs from private sources indicates that a 2-mile stretch of the channel near North Columbia contains over half a million ounces of gold dispersed through about 22 million cubic yards of gravel at a grade .averaging about 81 cents per cubic yard. The deposit is buried at depths ranging from 100 to 400 feet. Several geophysical methods have been tested for their feasibility in determining the configuration of the buried bedrock surface, in delineating channel gravel buried under volcanic rocks, and in identifying concentrations of heavy minerals within the gravel. Although the data have not yet been completely processed, preliminary conclusions indicate that some methods may be quite useful. A combination of seismic-refraction and gravity methods was used to determine the depth and configuration of the bottom of the channel to an accuracy within 10 percent as checked by the drill holes

  11. Preliminary report on deposit models for sand and gravel in the Cache la Poudre River valley

    USGS Publications Warehouse

    Langer, W.H.; Lindsey, D.A.

    1999-01-01

    The stratigraphy, sedimentary features, and physical characteristics of gravel deposits in the Cache la Poudre River valley were studied to establish geologic models for these deposits. Because most of the gravel mined in the valley is beneath the low terraces and floodplain, the quality of these deposits for aggregate was studied in detail at eight sites in a 25.5-mile reach between Fort Collins and Greeley, Colorado. Aggregate quality was determined by field and laboratory measurements on samples collected under a consistent sampling plan. The Broadway terrace is underlain by Pleistocene alluvium and, at some places, by fine-grained wind-blown deposits. The Piney Creek terrace, low terraces, and floodplain are primarily underlain by Holocene alluvium. Pleistocene alluvium may underlie these terraces at isolated locations along the river. Gravels beneath the Piney Creek terrace, low terraces, and floodplain are divisible into two units that are poorly distinguishable at the upstream end of the study area, but are readily distinguishable about 7 miles downstream. Where distinguished, the two gravel units are separated by a sharp, locally erosional, contact. The upper gravel is probably of Holocene age, but the lower gravel is considered to be Holocene and Pleistocene. The primary variation in particle size of the gravels beneath the floodplain and low terraces of the Cache la Poudre River valley is the downstream decrease in the proportion of particles measuring 3/4 inch and larger. Above Fort Collins, about 60 pct of the gravel collects on the 3/4 inch sieve, whereas about 50 pct of gravel collects on the same sieve size at Greeley. For 1.5-inch sieves, the corresponding values are about 50 pct for Fort Collins and only about 30 pct for Greeley. Local differences in particle size and sorting between the upper and lower gravel units were observed in the field, but only the coarsest particle sizes appear to have been concentrated in the lower unit. Field

  12. The effect of lateral confinement on gravel bed river morphology

    NASA Astrophysics Data System (ADS)

    Garcia Lugo, G. A.; Bertoldi, W.; Henshaw, A. J.; Gurnell, A. M.

    2015-09-01

    In this paper, we use a physical modeling approach to explore the effect of lateral confinement on gravel bed river planform style, bed morphology, and sediment transport processes. A set of 27 runs was performed in a large flume (25 m long, 2.9 m wide), with constant longitudinal slope (0.01) and uniform grain size (1 mm), changing the water discharge (1.5-2.5 L/s) and the channel width (0.15-1.5 m) to model a wide range of channel configurations, from narrow, straight, embanked channels to wide braided networks. The outcomes of each run were characterized by a detailed digital elevation model describing channel morphology, a map of dry areas and areas actively transporting sediment within the channel, and continuous monitoring of the amount of sediment transported through the flume outlet. Analysis reveals strong relationships between unit stream power and parameters describing the channel morphology. In particular, a smooth transition is observed between narrow channels with an almost rectangular cross-section profile (with sediment transport occurring across the entire channel width) and complex braided networks where only a limited proportion (30%) of the bed is active. This transition is captured by descriptors of the bed elevation frequency distribution, e.g., standard deviation, skewness, and kurtosis. These summary statistics represent potentially useful indicators of bed morphology that are compared with other commonly used summary indicators such as the braiding index and the type and number of bars.

  13. Integrated automatic and continuous bedload monitoring in gravel bed rivers

    NASA Astrophysics Data System (ADS)

    Habersack, Helmut; Kreisler, Andrea; Rindler, Rolf; Aigner, Johann; Seitz, Hugo; Liedermann, Marcel; Laronne, Jonathan B.

    2017-08-01

    Bedload monitoring techniques have been developed and applied for many years in rivers ranging from steep mountain torrents to the large gravel-bed Danube River in Austria. Most monitoring stations use a combination of direct (mobile bag samplers, slot samplers) and indirect (geophones, hydrophones) measurement methods. Each individual technique is adequate, yet features particular boundary conditions and limitations related to hydraulic and sampling efficiency, functionality during floods, sampling duration or grain size. We show the capabilities and limitations of the different monitoring devices with respect to technical, operational and economic criteria, evaluating their suitability for determining bedload transport parameters. Bedload monitoring results of a measuring site at the Drau River in Carinthia/Austria are used to illustrate the specific range of the device application. We present an integrated automatic and continuous bedload monitoring system. It complements the specific limitations of single monitoring methods by additional measurement devices, enabling comprehensive monitoring of the bedload transport process. We then derive the Bedload Discharge Integrated Calculation Approach and the Bedload Rating Curve Approach and discuss their application for determining bedload discharge Qb and total bedload mass Vb. Whereas the integrated approach combines data from direct monitoring methods with indirect techniques, the rating curve approach uses only data from direct bedload monitoring devices. We demonstrate that applying an integrated automatic and continuous bedload monitoring system and combining the Bedload Discharge Integrated Calculation Approach and Bedload Rating Curve Approach yields accurate bedload discharge results.

  14. [Effects of gravel mulch technology on soil erosion resistance and plant growth of river flinty slope].

    PubMed

    Zhu, Wei; Xie, San-Tao; Ruan, Ai-Dong; Bian, Xun-Wen

    2008-03-01

    Aiming at the technical difficulties such as the stability and water balance in the ecological rehabilitation of river flinty slope, a gravel mulch technology was proposed, with the effects of different gravel mulch treatments on the soil anti-erosion capacity, soil water retention property, and plant growth investigated by anti-erosion and pot experiments. The results showed that mulching with the gravels 1.5-2 cm in size could obviously enhance the soil anti-erosion capacity, soil water retention property and plant biomass, but no obvious differences were observed between the mulch thickness of 5 cm and 8 cm. It was indicated that mulching with the gravels 1.5-2 cm in size and 5 cm in thickness was an effective and economical technology for the ecological rehabilitation of river flinty slope.

  15. Minor NSR Permit: Crossfire Aggregate Services, LLC - Crossfire Bonds Gravel Pit

    EPA Pesticide Factsheets

    This page contains the response to public comments and final minor NSR permit for the Crossfire Bonds Gravel Pit, operated by Crossfire Aggregate Services, LLC, and located on the Southern Ute Indian Reservation in La Plata County, Colorado.

  16. Gravel resources, urbanization, and future land use, Front Range Urban Corridor, Colorado

    USGS Publications Warehouse

    Soule, James M.; Fitch, Harold R.

    1974-01-01

    An assessment of gravel needs in Front Range Urban Corridor markets to 2000 A.D., based on forecast population increases and urbanization, indicates that adequate resources to meet anticipated needs are potentially available, if future land use does not preclude their extraction. Because of urban encroachment onto gravel-bearing lands, this basic construction material is in short supply nationally and in the Front Range Urban Corridor. Longer hauls, increased prices, and use of alternatives, especially crushed rock aggregate, have resulted. An analysis of possible sequential land uses following gravel mining indicates that a desirable use is for 'real estate' ponds and small lakes. A method for computing gravel reserves, based on planimeter measurement of area of resource-bearing lands and statistical analysis of reliability of thickness and size distribution data, was developed to compute reserves in individual markets. A discussion of the qualitative 'usability' of these reserves is then made for the individual markets.

  17. TECHNIQUES TO DETERMINE SPATIAL VARIATIONS IN HYDRAULIC CONDUCTIVITY OF SAND AND GRAVEL

    EPA Science Inventory

    Methods for determining small-scale variations in aquifer properties were investigated for a sand and gravel aquifer on Cape Cod, Massachusetts. easurements of aquifer properties, in particular hydraulic conductivity, are needed for further investigations into the effects of aqui...

  18. TECHNIQUES TO DETERMINE SPATIAL VARIATIONS IN HYDRAULIC CONDUCTIVITY OF SAND AND GRAVEL

    EPA Science Inventory

    Methods for determining small-scale variations in aquifer properties were investigated for a sand and gravel aquifer on Cape Cod, Massachusetts. easurements of aquifer properties, in particular hydraulic conductivity, are needed for further investigations into the effects of aqui...

  19. Statistical analysis of sand and gravel aggregate deposits of late Pleistocene Lake Bonneville, Utah

    USGS Publications Warehouse

    Bliss, James D.; Bolm, K.S.

    2001-01-01

    Sedimentary deposits of pluvial Lake Bonneville are an important source of sand and gravel suitable for aggregate and construction in Utah. Data on Lake Bonneville basin sand and gravel deposit thickness, volume, grain size, percent of fines, and durability were statistically analyzed to detect variations associated with geologic domains, geographic location, Lake Bonneville shorelines, and sand and gravel deposit type, and to construct quantitative deposit models. Analysis showed several trends; (1) sand and gravel in younger shorelines was slightly more durable and the deposits considerably larger in volume, (2) younger shorelines are also more likely to contain more than one genetic deposit type, (3) the volume of terrace deposits is larger than beach deposits, (4) terraces and beaches are generally thicker than spits and bars, (5) the northern part of the Bonneville Basin contains slightly more durable sand and gravel than the southern part of the basin and is more likely to contain deposits composed of more than one genetic deposit type, and (6) the Wasatch domain deposits are composed of more than one genetic deposit type more often than deposits of the Basin and Range domain. Three additional conclusions with immediate economic significance are; (1) the median sand and gravel deposit in the Wasatch domain, 360,000 m3 (275,000 yd3), is three times larger than that of the Basin and Range domain (120,000 m3 [90,000 yd3]), (2) the median deposit thickness in the Wasatch domain, 5.8 m (19.0 ft), is nearly twice that of the Basin and Range domain (3 m [10 ft]), and (3) the Wasatch domain also contains slightly larger diameter gravel. These three conclusions are significant because the trend for sand and gravel development in the Bonneville Basin is to move from the Wasatch domain to the Basin and Range domain. Smaller, thinner deposits with smaller diameter gravel will require more surface area to mine than would have been necessary in the Wasatch domain. The

  20. A new method for reporting and interpreting textural composition of spawning gravel.

    Treesearch

    Fredrick B. Lotspeich; Fred H. Everest

    1981-01-01

    A new method has been developed for collecting, sorting, and interpreting gravel quality. Samples are collected with a tri-tube freeze-core device and dry-sorted by using sieves based on the Wentworth scale. An index to the quality of gravel is obtained by dividing geometric mean particle size by the sorting coefficient (a measure of the distribution of grain sizes) of...

  1. Hydrogeology of sand and gravel deposits near Nepaug Reservoir, New Hartford and Burlington, Connecticut

    USGS Publications Warehouse

    Stone, Janet Radway; Starn, J. Jeffrey; Morrison, Jonathan

    2001-01-01

    Sand and gravel deposits near the Nepaug Reservoir in New Hartford and Burlington, Connecticut, were studied to provide a basis for ongoing investigations that will evaluate water-quality conditions in the watershed and the effects of sand and gravel mining on the quality of water in the reservoir. In the Nepaug area, surficial glacial materials overlie crystalline bedrock that is predominantly schist and gneiss. Along the western side of Nepaug Reservoir, glacial stratified deposits were laid down as ice-marginal deltas in a series of small glacial lakes that formed sequentially as the ice margin retreated northeastward through the area. These deposits are as much as 250 feet thick and are subdivided into coarse-grained units (gravel, sand and gravel, and sand deposits) and fine-grained units (very fine sand, silt, and clay deposits). Approximately 954 million cubic feet of sand and gravel is contained in four delineated deposits in two areas near the reservoir. The sand and gravel deposits adjacent to the Nepaug Reservoir can affect the physical and chemical responses of the watershed. Removal of the sand and gravel would likely result in increased streamflow peaks associated with storms and decreased streamflow during low-flow periods. Streamflow during floods and droughts at Burlington Brook and Clear Brook, a tributary to the Nepaug Reservoir, were compared to determine how the volume of sand and gravel in a watershed affects ground-water storage and the way water is released from storage. Removal of unsaturated deposits also may affect chemical interactions between water and sediment and cause changes in the amount of dissolved constituents in the water.

  2. Macroinvertebrate community responses to gravel augmentation in a high-gradient, Southeastern regulated river

    SciTech Connect

    McManamay, Ryan A; Orth, Dr. Donald J; Dolloff, Dr. Charles A

    2013-01-01

    Sediment transport, one of the key processes of river systems, is altered or stopped by dams, leaving lower river reaches barren of sand and gravel, both of which are essential habitat for fish and macroinvertebrates. One way to compensate for losses in sediment is to supplement gravel to river reaches below impoundments. Because gravel addition has become a widespread practice, it is essential to evaluate the biotic response to restoration projects in order to improve the efficacy of future applications. The purpose of our study was to evaluate the response of the macroinvertebrate community to gravel addition in a high-gradient, regulated river in western North Carolina. We collected benthic macroinvertebrate samples from gravel-enhanced areas and unenhanced areas for 1 season before gravel addition, and for 4 seasons afterwards. Repeated measures multivariate analysis of variance indicated that the responses of macroinvertebrates to gravel addition were generally specific to individual taxa or particular functional feeding groups and did not lead to consistent patterns in overall family richness, diversity, density, or evenness. Non-metric multi-dimensional scaling showed that shifts in macroinvertebrate community composition were temporary and dependent upon site conditions and season. Correlations between macroinvertebrate response variables and substrate microhabitat variables existed with or without the inclusion of data from enhanced areas, which suggests that substrate-biotic relationships were present before gravel addition. A review of the current literature suggests that the responses of benthic macroinvertebrates to substrate restoration are inconsistent and dependent upon site conditions and the degree habitat improvement of pre-restoration site conditions.

  3. Measurement of coarse gravel and cobble transport using portable bedload traps

    Treesearch

    Kristin Bunte; Steven R. Abt; John P. Potyondy; Sandra E. Ryan

    2004-01-01

    Portable bedload traps (0.3 by 0.2 m opening) were developed for sampling coarse bedload transport in mountain gravel-bed rivers during wadable high flows. The 0.9 m long trailing net can capture about 20 kg of gravel and cobbles. Traps are positioned on ground plates anchored in the streambed to minimize disturbance of the streambed during sampling. This design...

  4. Gravel-bed river floodplains are the ecological nexus of glaciated mountain landscapes

    PubMed Central

    Hauer, F. Richard; Locke, Harvey; Dreitz, Victoria J.; Hebblewhite, Mark; Lowe, Winsor H.; Muhlfeld, Clint C.; Nelson, Cara R.; Proctor, Michael F.; Rood, Stewart B.

    2016-01-01

    Gravel-bed river floodplains in mountain landscapes disproportionately concentrate diverse habitats, nutrient cycling, productivity of biota, and species interactions. Although stream ecologists know that river channel and floodplain habitats used by aquatic organisms are maintained by hydrologic regimes that mobilize gravel-bed sediments, terrestrial ecologists have largely been unaware of the importance of floodplain structures and processes to the life requirements of a wide variety of species. We provide insight into gravel-bed rivers as the ecological nexus of glaciated mountain landscapes. We show why gravel-bed river floodplains are the primary arena where interactions take place among aquatic, avian, and terrestrial species from microbes to grizzly bears and provide essential connectivity as corridors for movement for both aquatic and terrestrial species. Paradoxically, gravel-bed river floodplains are also disproportionately unprotected where human developments are concentrated. Structural modifications to floodplains such as roads, railways, and housing and hydrologic-altering hydroelectric or water storage dams have severe impacts to floodplain habitat diversity and productivity, restrict local and regional connectivity, and reduce the resilience of both aquatic and terrestrial species, including adaptation to climate change. To be effective, conservation efforts in glaciated mountain landscapes intended to benefit the widest variety of organisms need a paradigm shift that has gravel-bed rivers and their floodplains as the central focus and that prioritizes the maintenance or restoration of the intact structure and processes of these critically important systems throughout their length and breadth. PMID:27386570

  5. Domestic well capture zone and influence of the gravel pack length.

    PubMed

    Horn, Judith E; Harter, Thomas

    2009-01-01

    Domestic wells in North America and elsewhere are typically constructed at relatively shallow depths and with the sand or gravel pack extending far above the intake screen of the well (shallow well seal). The source areas of these domestic wells and the effect of an extended gravel pack on the source area are typically unknown, and few resources exist for estimating these. In this article, we use detailed, high-resolution ground water modeling to estimate the capture zone (source area) of a typical domestic well located in an alluvial aquifer. Results for a wide range of aquifer and gravel pack hydraulic conductivities are compared to a simple analytical model. Correction factors for the analytical model are computed based on statistical regression of the numerical results against the analytical model. This tool can be applied to estimate the source area of a domestic well for a wide range of conditions. We show that an extended gravel pack above the well screen may contribute significantly to the overall inflow to a domestic well, especially in less permeable aquifers, where that contribution may range from 20% to 50% and that an extended gravel pack may lead to a significantly elongated capture zone, in some instances, nearly doubling the length of the capture zone. Extending the gravel pack much above the intake screen therefore significantly increases the vulnerability of the water source.

  6. Time-averaged Turbulent Flow Characteristics over a Highly Spatially Heterogeneous Gravel-Bed

    NASA Astrophysics Data System (ADS)

    Sarkar, Sankar

    2016-10-01

    The present study focuses on the time-averaged turbulence characteristics over a highly spatially-heterogeneous gravel-bed. The timeaveraged streamwise velocity, Reynolds shear and normal stresses, turbulent kinetic energy, higher-order moments of velocity fluctuations, length scales, and the turbulent bursting were measured over a gravel-bed with an array of larger gravels. It was observed that the turbulence characteristics do not vary significantly above the crest level of the array as compared to those below the array. The nondimensional streamwise velocity decreases considerably with a decrease in depth below the array. Below the array, the Reynolds shear stress (RSS) deviates from the gravity- law of RSS distributions. Turbulence intensities reduce below the crest level of the gravel-bed. The third-order moments of velocity fluctuations increase below the crest level of the gravel-bed and give a clear indication of sweeps as the predominating event which were further verified with the quadrant analysis plots. The turbulent length scales values change significantly below the crest level of the gravel-bed.

  7. Gravel-bed river floodplains are the ecological nexus of glaciated mountain landscapes

    USGS Publications Warehouse

    Hauer, F. Richard; Locke, Harvey; Dreitz, Victoria; Hebblewhite, Mark; Lowe, Winsor; Muhlfeld, Clint C.; Nelson, Cara; Proctor, Michael F; Rood, Stewart B.

    2016-01-01

    Gravel-bed river floodplains in mountain landscapes disproportionately concentrate diverse habitats, nutrient cycling, productivity of biota, and species interactions. Although stream ecologists know that river channel and floodplain habitats used by aquatic organisms are maintained by hydrologic regimes that mobilize gravel-bed sediments, terrestrial ecologists have largely been unaware of the importance of floodplain structures and processes to the life requirements of a wide variety of species. We provide insight into gravel-bed rivers as the ecological nexus of glaciated mountain landscapes. We show why gravel-bed river floodplains are the primary arena where interactions take place among aquatic, avian, and terrestrial species from microbes to grizzly bears and provide essential connectivity as corridors for movement for both aquatic and terrestrial species. Paradoxically, gravel-bed river floodplains are also disproportionately unprotected where human developments are concentrated. Structural modifications to floodplains such as roads, railways, and housing and hydrologicaltering hydroelectric or water storage dams have severe impacts to floodplain habitat diversity and productivity, restrict local and regional connectivity, and reduce the resilience of both aquatic and terrestrial species, including adaptation to climate change. To be effective, conservation efforts in glaciated mountain landscapes intended to benefit the widest variety of organisms need a paradigm shift that has gravel-bed rivers and their floodplains as the central focus and that prioritizes the maintenance or restoration of the intact structure and processes of these critically important systems throughout their length and breadth.

  8. Gravel-bed river floodplains are the ecological nexus of glaciated mountain landscapes.

    PubMed

    Hauer, F Richard; Locke, Harvey; Dreitz, Victoria J; Hebblewhite, Mark; Lowe, Winsor H; Muhlfeld, Clint C; Nelson, Cara R; Proctor, Michael F; Rood, Stewart B

    2016-06-01

    Gravel-bed river floodplains in mountain landscapes disproportionately concentrate diverse habitats, nutrient cycling, productivity of biota, and species interactions. Although stream ecologists know that river channel and floodplain habitats used by aquatic organisms are maintained by hydrologic regimes that mobilize gravel-bed sediments, terrestrial ecologists have largely been unaware of the importance of floodplain structures and processes to the life requirements of a wide variety of species. We provide insight into gravel-bed rivers as the ecological nexus of glaciated mountain landscapes. We show why gravel-bed river floodplains are the primary arena where interactions take place among aquatic, avian, and terrestrial species from microbes to grizzly bears and provide essential connectivity as corridors for movement for both aquatic and terrestrial species. Paradoxically, gravel-bed river floodplains are also disproportionately unprotected where human developments are concentrated. Structural modifications to floodplains such as roads, railways, and housing and hydrologic-altering hydroelectric or water storage dams have severe impacts to floodplain habitat diversity and productivity, restrict local and regional connectivity, and reduce the resilience of both aquatic and terrestrial species, including adaptation to climate change. To be effective, conservation efforts in glaciated mountain landscapes intended to benefit the widest variety of organisms need a paradigm shift that has gravel-bed rivers and their floodplains as the central focus and that prioritizes the maintenance or restoration of the intact structure and processes of these critically important systems throughout their length and breadth.

  9. Mapping Gravel-Bed River Bathymetry from Space

    NASA Astrophysics Data System (ADS)

    Legleiter, C. J.; Overstreet, B. T.

    2012-12-01

    Understanding the form and behavior of rivers requires efficient means of measuring their morphology and dynamics. Conventional field methods are inadequate for this task, but remote sensing techniques have emerged as a viable alternative. This study evaluated the potential to map the bathymetry of clear-flowing gravel-bed rivers from satellite images. Direct measurements of water column optical properties also were used to quantify constraints associated with depth retrieval. The smallest detectable change in depth was 0.01 - 0.04 m and the maximum detectable depth was 5 m in green bands but < 2 m in the near-infrared; sensors with lower radiometric resolution would yield less precise estimates over a smaller range. A band ratio-based algorithm for identifying optimal wavelength combinations and calibrating the image-derived quantity X to depth d proved effective when applied to spectra extracted from images (R2 = 0.822 and 0.594 for the larger and smaller stream, respectively) or, to a lesser degree, measured in the field (R2 = 0.769 and 0.452). Accuracy assessment of bathymetric maps produced using various calibration approaches and image types indicated that: 1) a linear relationship between d and X provided depth estimates nearly as reliable as a quadratic formulation; 2) panchromatic and pan-sharpened multispectral images with smaller pixels did not yield more reliable depth estimates than the original, coarser-resolution images; and 3) depth retrieval was less reliable in pools due to saturation of the radiance signal. This investigation thus demonstrated the feasibility, as well as the limitations, of measuring river bathymetry from space. Image-derived depth maps for Rusty Bend of the Snake River produced using various calibration approaches and image data types. All maps have a common color scale shown at the bottom. Flow is from right to left.

  10. Stream-power model of meander cutoff in gravel beds

    NASA Astrophysics Data System (ADS)

    Pannone, M.; De Vincenzo, A.

    2016-12-01

    In the present study we propose a one-dimensional model for the prediction of the large-time evolution of river meanders (pre-cutoff conditions) characterized by gravel bed and negligible suspended load. Due to its relatively simple structure, it may be a fast and easy tool to forecast the time evolution of a bend when the symptoms of an incipient instability suggest quantifying the time left for river exploitation as a naturalistic or a commercial resource and timely planning, if needed, the site management and restoration. Most of the previous research on meandering rivers focused on linearized theories that apply to very small bend amplitudes and very large radii of curvature. The dynamics of meander growth and cutoff was typically afforded by case-sensitive numerical simulations or by descriptive methods aimed at deriving purely empirical laws relating the hydraulics to some geomorphological parameters. The present approach combines the immediacy of a general analytical model with the accuracy of a fluid-mechanical background. The model focuses on energetic principles and interprets the mechanism of meander cutoff as the achievement of limit conditions in terms of river stream power. The corresponding analytical solution, which consists in a 1-D deterministic integro-differential equation governing the meander pre-cutoff phase, accounts for the influence of the morphological and sedimentological parameters by the downstream migration rate and the radius of the meander osculating circle. The results, expressed in terms of instable meander lifetime, are in good agreement with the data obtained from a number of field surveys documented in literature. Additionally, the proposed fluid-mechanical model allows identifying the physical mechanisms responsible for some peculiarities of large-time meander evolution like the decreasing skewness and asymmetry.

  11. Strong effect of coarse surface layer on moisture within gravel bars: Results from an outdoor experiment

    NASA Astrophysics Data System (ADS)

    Meier, Claudio I.; Hauer, F. Richard

    2010-05-01

    We propose that the coarse surface layer found on most gravel bars acts as mulch, decreasing evaporation from the soil surface and maintaining higher moisture levels in the underlying fine matrix, as compared with the case of sand bed streams. Because of the importance that such process would have for vegetation establishment, we conducted an outdoor evaporation experiment on soil columns containing diverse mixtures of fines and gravel, covered with 0, 4, and 8 cm thick gravel layers, as well as columns with homogeneous sand. The columns were saturated, drained, and then exposed to the atmosphere for 58 days. They were weighed and their soil moisture was computed on eight different dates. Both the coarse layer thickness and the texture of the underlying fine matrix, as well as their interaction, had significant effects on soil moisture. The presence of 4 and 8 cm thick gravel layers on the surface increased moisture up to 3.7 and 5.3 times, respectively, as compared with homogeneous sand. Effects of the fine matrix texture were significant only when the fines were exposed to the atmosphere at the top of the columns, but not when a coarse layer was present. Our results show that the presence of a clean gravel layer maintains high moisture levels within the underlying fines, for periods of weeks without water input. We suggest that this rock mulching effect could be fundamental for successful plant colonization of bare gravel bars, so that it should be incorporated into any vegetation establishment model developed for gravel bed rivers.

  12. Sorption, mineralization and mobility of N-(phosphonomethyl)glycine (glyphosate) in five different types of gravel.

    PubMed

    Strange-Hansen, Rikke; Holm, Peter E; Jacobsen, Ole S; Jacobsen, Carsten S

    2004-06-01

    Sorption, mineralization and mobility of glyphosate were studied in six substrates: the five types of gravel most frequently used as surfacing in Denmark and a sandy agricultural soil from Simmelkaer that served as a reference soil. Cumulative mineralization of [methyl-14C]glyphosate in batch studies was highest in coarse gravel, amounting to 14% after 4 days at 30 degrees C and 32% after 31 days. Mineralization was slowest in the sandy reference soil, amounting to only 2% after 31 days. The adsorption coefficient (Kd) of glyphosate in gravel ranged from 62 to 164 litre kg(-1), while that in the sandy reference soil was 410 litre kg(-1). The results indicate that the relatively low Kd in gravel allows a relatively high rate of glyphosate mineralization by the biomass. When Kd is high, in contrast, mineralization is slow. Lowering the temperature to 10 degrees C decreased mineralization by 50% in one of two gravels. The leaching of glyphosate was screened in simple columns of gravel or soil in which precipitation events (20 mm over a 2-h period) were simulated on three occasions, starting either immediately after or 2 days after application of glyphosate. [14C]Glyphosate was applied as a tracer mixed with the commercial product Roundup Garden at the recommended rate of 2.4 kg glyphosate ha(-1), equivalent to 1 microg g(-1) soil. The highest concentration of [14C] compounds (expressed in terms of glyphosate concentration) in leachate from the columns exceeded 1300 microg litre(-1), and was detected in rounded gravel after the first rain event. No glyphosate was detected in leachate from the sandy reference soil.

  13. Timing of early Quaternary gravel accumulation in the Swiss Alpine Foreland

    NASA Astrophysics Data System (ADS)

    Anne, Claude; Naki, Akçar; Susan, Ivy-Ochs; Fritz, Schlunegger; Peter, Kubik W.; Andreas, Dehnert; Joachim, Kuhlemann; Meinert, Rahn; Christian, Schlüchter

    2017-01-01

    Deckenschotter ('Cover Gravels') are proximal glaciofluvial gravels located in the northern Alpine Foreland mainly beyond the extent of the Last Glacial Maximum. They cover Tertiary Molasse or Mesozoic bedrock with an erosional unconformity. In Switzerland, Deckenschotter are referred to as Höhere (Higher) and Tiefere (Lower) Deckenschotter based on their topographical positions with a significant phase of incision that separates these two units. For this study, we performed sedimentological analyses to identify the provenance, transport mechanisms and depositional environment of these gravels. In addition, we established the chronology of the Höhere Deckenschotter gravels at Stadlerberg using cosmogenic 10Be depth-profile dating technique. The inherited 10Be concentration then allowed estimation of a catchment-wide palaeo-denudation rate. The results from clast fabric investigations indicate that braided rivers within a glaciofluvial environment transported these sediments to the study site mainly as bedload. In addition, the petrographic composition of the deposits shows that a large portion of the gravels was derived through erosional recycling of Miocene Molasse conglomerates. Some material was additionally sourced in the northern Central Alps. We then conclude that gravel accumulation in the Swiss Alpine Foreland was completed at 1.9 ± 0.2 Ma. This age, however, represents a minimum age and the oldest 10Be depth-profile age ever obtained for a geological unit. Furthermore, a palaeo-denudation rate of c. 0.3-0.4 mm/a was estimated for the catchment of Stadlerberg gravels. Finally, elevation differences between the bedrock underlying the Höhere Deckenschotter and the modern base level imply a long-term regional incision rate of c. 0.12 mm/a.

  14. Measurement of the bed material of gravel-bed rivers

    USGS Publications Warehouse

    Milhous, R.T.; ,

    2002-01-01

    The measurement of the physical properties of a gravel-bed river is important in the calculation of sediment transport and physical habitat values for aquatic animals. These properties are not always easy to measure. One recent report on flushing of fines from the Klamath River did not contain information on one location because the grain size distribution of the armour could not be measured on a dry river bar. The grain size distribution could have been measured using a barrel sampler and converting the measurements to the same as would have been measured if a dry bar existed at the site. In another recent paper the porosity was calculated from an average value relation from the literature. The results of that paper may be sensitive to the actual value of porosity. Using the bulk density sampling technique based on a water displacement process presented in this paper the porosity could have been calculated from the measured bulk density. The principle topics of this paper are the measurement of the size distribution of the armour, and measurement of the porosity of the substrate. The 'standard' method of sampling of the armour is to do a Wolman-type count of the armour on a dry section of the river bed. When a dry bar does not exist the armour in an area of the wet streambed is to sample and the measurements transformed analytically to the same type of results that would have been obtained from the standard Wolman procedure. A comparison of the results for the San Miguel River in Colorado shows significant differences in the median size of the armour. The method use to determine the porosity is not 'high-tech' and there is a need improve knowledge of the porosity because of the importance of porosity in the aquatic ecosystem. The technique is to measure the in-situ volume of a substrate sample by measuring the volume of a frame over the substrate and then repeated the volume measurement after the sample is obtained from within the frame. The difference in the

  15. Streambed Deformation and Adjustments in a Gravel-Bed Channel

    NASA Astrophysics Data System (ADS)

    Haschenburger, J. K.

    2005-12-01

    The streambed is the major source of bedload sediment in gravel-bed channels and is necessarily deformed during competent flows. At the local scale, net adjustments to streambeds are well documented through repeated survey of channel cross sections in a wide range of rivers. However, evaluating the end result of sediment transfers provides little insight into how changes occur through scour and fill processes. This research connects the contributions of scour and fill to net adjustments in streambed elevation over a series of flood events. Field observations come from Carnation Creek, British Columbia, where over 100 scour indicators were installed in a 900 m study reach and recovered 15 times during two flood seasons. Peak discharges (Q) ranged from 3.6 to 36.3 m3s-1, the largest representing a return period of about 7 years. The relatively limited coarse surface layer facilitates an active streambed and relatively high sediment transport rates typically under partial transport conditions. The mean bed elevation was relatively stable over the field program, showing only minor degradation in response to the two largest floods. The likelihood of both scour and fill occurring at a given location increases from 0.2 to 0.8 as flow increases. The dominance of only scour when Q<11 m3s-1 gives way to both processes at the higher flows observed. The bed undergoes more numerous and larger net adjustments as flow increases. At flows near incipient motion, the largest net adjustments were 0.5 times the thickness of the coarse surface layer (D90), and at large flows, they reached 5D90 for both net scour and fill. During the largest flood, depths of scour and fill reached 8D90 with 30% of the active locations experiencing depths >2D90. As the likelihood of neither scour nor fill occurring declines with flow, the explanation of stable bed elevations shifts from inactivity toward compensating depths of scour and fill. These results indicate that conditions favorable to both

  16. Unique Microbial Phylotypes in Namib Desert Dune and Gravel Plain Fairy Circle Soils

    PubMed Central

    van der Walt,, Andries J.; Johnson, Riegardt M.; Cowan, Don A.; Seely, Mary

    2016-01-01

    ABSTRACT Fairy circles (FCs) are barren circular patches of soil surrounded by grass species. Their origin is poorly understood. FCs feature in both the gravel plains and the dune fields of the Namib Desert. While a substantial number of hypotheses to explain the origin and/or maintenance of fairy circles have been presented, none are completely consistent with either their properties or their distribution. In this study, we investigated the hypothesis that FC formation in dunes and gravel plains is due to microbial phytopathogenesis. Surface soils from five gravel plain and five dune FCs, together with control soil samples, were analyzed using high-throughput sequencing of bacterial/archaeal (16S rRNA gene) and fungal (internal transcribed spacer [ITS] region) phylogenetic markers. Our analyses showed that gravel plain and dune FC microbial communities are phylogenetically distinct and that FC communities differ from those of adjacent vegetated soils. Furthermore, various soil physicochemical properties, particularly the pH, the Ca, P, Na, and SO4 contents, the soil particle size, and the percentage of carbon, significantly influenced the compositions of dune and gravel plain FC microbial communities, but none were found to segregate FC and vegetated soil communities. Nevertheless, 9 bacterial, 1 archaeal, and 57 fungal phylotypes were identified as FC specific, since they were present within the gravel plain and dune FC soils only, not in the vegetated soils. Some of these FC-specific phylotypes were assigned to taxa known to harbor phytopathogenic microorganisms. This suggests that these FC-specific microbial taxa may be involved in the formation and/or maintenance of Namib Desert FCs. IMPORTANCE Fairy circles (FCs) are mysterious barren circular patches of soil found within a grass matrix in the dune fields and gravel plains of the Namib Desert. Various hypotheses attempting to explain this phenomenon have been proposed. To date, however, none have been

  17. Unique Microbial Phylotypes in Namib Desert Dune and Gravel Plain Fairy Circle Soils.

    PubMed

    van der Walt, Andries J; Johnson, Riegardt M; Cowan, Don A; Seely, Mary; Ramond, Jean-Baptiste

    2016-08-01

    Fairy circles (FCs) are barren circular patches of soil surrounded by grass species. Their origin is poorly understood. FCs feature in both the gravel plains and the dune fields of the Namib Desert. While a substantial number of hypotheses to explain the origin and/or maintenance of fairy circles have been presented, none are completely consistent with either their properties or their distribution. In this study, we investigated the hypothesis that FC formation in dunes and gravel plains is due to microbial phytopathogenesis. Surface soils from five gravel plain and five dune FCs, together with control soil samples, were analyzed using high-throughput sequencing of bacterial/archaeal (16S rRNA gene) and fungal (internal transcribed spacer [ITS] region) phylogenetic markers. Our analyses showed that gravel plain and dune FC microbial communities are phylogenetically distinct and that FC communities differ from those of adjacent vegetated soils. Furthermore, various soil physicochemical properties, particularly the pH, the Ca, P, Na, and SO4 contents, the soil particle size, and the percentage of carbon, significantly influenced the compositions of dune and gravel plain FC microbial communities, but none were found to segregate FC and vegetated soil communities. Nevertheless, 9 bacterial, 1 archaeal, and 57 fungal phylotypes were identified as FC specific, since they were present within the gravel plain and dune FC soils only, not in the vegetated soils. Some of these FC-specific phylotypes were assigned to taxa known to harbor phytopathogenic microorganisms. This suggests that these FC-specific microbial taxa may be involved in the formation and/or maintenance of Namib Desert FCs. Fairy circles (FCs) are mysterious barren circular patches of soil found within a grass matrix in the dune fields and gravel plains of the Namib Desert. Various hypotheses attempting to explain this phenomenon have been proposed. To date, however, none have been successful in fully

  18. Tertiary fluvial gravels and evolution of the Western Canadian Prairie Landscape

    NASA Astrophysics Data System (ADS)

    Leckie, Dale A.

    2006-08-01

    The early Tertiary of Western Canada and northern United States was marked by a change from compressional to extensional tectonics. The result was regional uplift and magmatic events. The uplift resulted in a major unconformity and deposition of extensive regional sheets of gravel and sand, of which only isolated remnants remain. These units are the Eocene to Miocene Cypress Hills Formation, the Miocene Wood Mountain Formation, Miocene Flaxville Formation and preglacial Souris River gravels, All four stratigraphic units consist of gravel and sand with lesser amounts of clay. The formations were largely deposited as laterally continuous sheets of braided river gravels, with some occurrences of meandering-river sedimentation. The sediment was deposited several hundred kilometres downstream of their source areas. Paleocurrent data for the Cypress Hills and Wood Mountain formations indicate that regional paleoslope dipped towards the north-northeast. The modern prairie landscape of western Canada began to evolve with the deposition of these gravels during the Eocene with creation of a basin-wide unconformity followed by deposition of an extensive braidplain system that was subsequently uplifted, incised, and molded into its present form.

  19. Treatment of domestic wastewater by subsurface flow constructed wetlands filled with gravel and tire chip media.

    PubMed

    Richter, A Y; Weaver, R W

    2003-12-01

    Subsurface flow constructed wetlands (SFCWs) are becoming increasingly common in on-site treatment of wastewater. Gravel is the most popular form of wetland fill medium, but tire chips provide more porosity, are less dense, and less expensive. This study determines the treatment efficiency of SFCWs filled with gravel or tire chip media to treat domestic wastewater. The influent and effluent of six SFCWs filled with tire chip medium and six SFCWs filled with gravel were monitored for 5 to 16 consecutive months. Parameters measured included pH, biochemical oxygen demand (BOD5), total and volatile suspended solids, NH4, P, and fecal and total coliforms. The only clear difference between medium types in wetland performance was for P. Soluble P in the effluent averaged 1.6 +/- 1.0 mg l(-1) in the tire chip-filled wetlands and 4.8 +/- 3.2 mg l(-1) in the gravel-filled wetlands. Most likely, Fe from exposed wires in shredded steel-belted tires complexed with P to create an insoluble compound. Tire chips may be a better fill medium for SFCWs than gravel because of higher porosity, lower cost, and greater reduction of P in effluent.

  20. Pretreatment of turkey fat-containing wastewater in coarse sand and gravel/coarse sand bioreactors.

    PubMed

    Gaur, Rashmi Singh; Cai, Ling; Tuovinen, Olli H; Mancl, Karen M

    2010-02-01

    Fat, oil and grease in wastewater can be difficult to treat because of their slow decomposition. Traditional pretreatment facilities to remove fat, oil and grease from wastewater are increasingly costly. The hypothesis in this study was that pretreatment of animal fat-containing wastewater in sand and sand/gravel filters facilitates the conversion of slowly degradable organic matter measured as the difference between chemical oxygen demand (COD) and 5-day biochemical oxygen demand (BOD(5)) for subsequent biological treatment. The pretreatment was evaluated using simulated turkey-processing wastewater and coarse sand and sand/gravel filters at a constant hydraulic loading rate of 132L/m(2)/day. Two types of fixed media reactors were employed: (i) one set with a varying depth of coarse sand, and (ii) the second was similar but with an additional pea gravel cap. The results indicated that the relative removal of COD was slightly improved in the sand bioreactors with a pea gravel cap irrespective of the depth of coarse sand, but partial conversion to BOD(5) was not consistently demonstrated. Pea gravel may act as a sieve to entrap organic matter including fat globules from the wastewater. Multiple dosing at the same daily loading rate slightly improved the treatment efficiency of the sand bioreactors. The ratios of influent-COD/effluent-COD were always greater than 1.0 following a change in the dosing frequency after a rest period, suggesting that organic matter, specifically fat globules in this case, was retained by the column matrix.

  1. TI-59 helps predict IPRs for gravel-packed gas wells

    SciTech Connect

    Capdevielle, W.C.

    1983-12-01

    The inflow performance relationship (IPR) is an important tool for reservoir and production engineers. It helps optimize completion, tubing, gas lift, and storm choke design. It facilitates accurate rate predictions that can be used to evaluate field development decisions. The IPR is the first step of the systems analysis that translates reservoir rock and fluid parameters into predictable flow rates. Use of gravel packing for sand control complicates the calculation that predicts a well's IPR curve, particularly in gas wells where high velocities in the formation and through gravel-filled perforation tunnels can cause turbulent flow. The program presented in this article calculates the pressure drop and the flowing bottomhole pressures at varying flow rates for gravel-packed gas wells. The program was written for a Texas Instruments TI-59 programmable calculator with a PC-100 printer. Program features include: Calculations for in-casing gravel packs, open-hole gravel packs, or ungravel packed wells. Program prompts for the required data variables. Easy change of data values to run new cases. Calculates pressures for an unlimited number of flow rates. Results show the total pressure drop and the relative magnitude of its components.

  2. Gravel admix, vegetation, and soil water interactions in protective barriers: Experimental design, construction, and initial conditions

    SciTech Connect

    Waugh, W.J.

    1989-05-01

    The purpose of this study is to measure the interactive effects of gravel admix and greater precipitation on soil water storage and plant abundance. The study is one of many tasks in the Protective Barrier Development Program for the disposal of Hanford defense waste. A factorial field-plot experiment was set up at the site selected as the borrow area for barrier topsoil. Gravel admix, vegetation, and enhanced precipitation treatments were randomly assigned to the plots using a split-split plot design structure. Changes in soil water storage and plant cover were monitored using neutron probe and point intercept methods, respectively. The first-year results suggest that water extraction by plants will offset gravel-caused increases in soil water storage. Near-surface soil water contents were much lower in graveled plots with plants than in nongraveled plots without plants. Large inherent variability in deep soil water storage masked any effects gravel may have had on water content below the root zone. In the future, this source of variation will be removed by differencing monthly data series and testing for changes in soil water storage. Tests of the effects of greater precipitation on soil water storage were inconclusive. A telling test will be possible in the spring of 1988, following the first wet season during which normal precipitation is doubled. 26 refs., 9 figs., 9 tabs.

  3. Valveless ash removal from pressurized fluidized-bed combustion systems by gravel bucket

    SciTech Connect

    Henderson, A.K.; Hauserman, W.B.

    1991-03-01

    The objective of this project is to apply the gravel bucket pressure letdown concept to a stream of hot, gas-borne ash, under conditions similar to those found in a pressurized fluidized-bed combustor, where the system pressure is dissipated across a packed or partially fluidized bed of coarsely crushed rock. A second objective is to use the data collected during testing to develop a mathematical model which can be used to predict pressure drop in a gravel bucket device. The final objective of the project is to develop an economic analysis comparing the cost of constructing and operating a gravel bucket with that of a lockhopper system. The results of this analysis will be submitted as a separate report. 9 refs., 6 figs., 5 tabs.

  4. Method of inhibiting gravel pack and formation sandstone dissolution during steam injection

    SciTech Connect

    Swan, P.G.

    1982-04-06

    A method is claimed of inhibiting dissolution of the gravel pack and/or erosion of the formation standstone in a well bore subject to water or steam injection. The method includes the addition of a material to the surface of the gravel or formation which is capable of adhering to such surfaces and forming a tenacious water-repellent film. The film is monomolecular and hydrophobic. The active ingredient in the chemical treatment is commercial soybean lecithin. The material is added to the surfaces by injecting a liquid solution of the chemical down the annulus of the well during steaming and/or physically precoating the gravel pack by soaking it in a liquid solution of the chemical.

  5. Hydrogeologic evaluation of a sand and gravel aquifer contaminated by wood-preserving compounds, Pensacola, Florida

    SciTech Connect

    Franks, B.J.

    1988-01-01

    The sand and gravel aquifer in southern Escambia County, Florida, is a typical surficial aquifer composed of quartz sands and gravels interbedded locally with silts and clays. Because creosote is the most extensively used industrial preservative in the US, an abandoned wood-treatment plant near Pensacola was chosen for investigation. This report describes the hydrogeology and groundwater flow system of the sand and gravel aquifer near the plant. A three-dimensional simulation of groundwater flow in the aquifer was evaluated under steady-state conditions. The model was calibrated on the basis of observed water levels from January 1986. Calibration criteria included reproducing all water levels within the accuracy of the data. Applications of the results of the calibrated flow model in evaluation of solute transport may require further discretization of the contaminated area, including more sublayers, than were needed for calibration of the groundwater flow system itself. 32 refs., 44 figs., 4 tabs.

  6. The origin, distribution, and depositional history of gravel deposits on the Beaufort Sea Continental Shelf, Alaska

    USGS Publications Warehouse

    Rodeick, Craig A.

    1979-01-01

    Two distinct gravel populations are present on the Beaufort Sea continental shelf. First, a geographically arcuate deposit that is convex seaward has been designated as the Chert Facies. This deposit is restricted to landward of the 10 meter bathymetric contour and west of Heald Point. The Chert Facies, originally a fluvial gravel deposit and probably part of the basal transgressive, represents reworked Gubik Formation. The Chert Facies is derived from the Brooks Range. The second population is the Dolomite Facies. This facies is a blanket deposit covering much of the shelf and occurs in most water depths greater than 10 meters. The Dolomite Facies extends on land into the Quaternary Gubik Formation east of Prudhoe Bay and probably to Point Barrow. Rocks of the Dolomite Facies are exotic to Alaska and represent ice rafted clasts. The distribution of the Dolomite Facies shelf gravel indicates an easterly source compatible with a proposed provenance surrounding the Amundsen Gulf of the Canadian Archipelago. Radiocarbon dates from undisturbed sediment underlying the gravel on the upper slope indicate that low Holocene sedimentation rates are the reason for gravel exposure in this region and on the outer shelf. Considerations of sea level fluctuations, possible times available for the transportation of gravel from the proposed source area to the study area, and radiocarbon dates indicate influxes of ice rafted debris during the mid-Wisconsin transgression and probably between 15, 000-10,000 years B. P. Correlation of the Gubik Formation at Heald Point with the Barrow unit of the Gubik Formation at Point Barrow on the basis of incorporated dolomite and orthoquartzite clasts is suggested.

  7. Large-scale restoration of salmon spawning habitat in a regulated, gravel-bedded river

    NASA Astrophysics Data System (ADS)

    Harrison, L.; Bray, E. N.; Overstreet, B. T.; Legleiter, C. J.; Dunne, T.

    2016-12-01

    Large-scale river restoration programs have recently emerged as a tool for improving salmon habitat in highly altered river ecosystems. Few studies have quantified the extent to which the restored habitat is utilized by salmonids, which physical processes contribute to improved biological functionality, or how the restored habitat changes over time. We investigated Pacific salmon spawning site utilization in two restored reaches of a gravel-bedded river: a site of gravel augmentation and habitat enhancement completed three years ago and a re-engineered, meandering channel and floodplain reach constructed over a decade ago. Spawning was observed at both sites in areas predicted to have high quality habitat, based on channel morphology and hydraulics. At the more recently restored gravel augmentation site, peak redd densities occurred in areas of high sediment mobility as determined by measurements of gravel pivot angles and a grain entrainment model. Redds were built in areas with high values of hydraulic conductivity and streambed hyporheic fluxes, which were located near the transition between pool-riffle bedforms in the re-engineered reach but spanned the entire length of the gravel-augmented reach. In situ measurements of streambed hydraulic conductivity indicated lower hyporheic fluxes at the re-engineered, meandering site due to the infiltration of fine sediment into the subsurface. Highly mobile and permeable gravels were heavily utilized for spawning in restored reaches amid an otherwise predominantly armored bed. However the potential long-term, ecological benefits provided by large-scale restoration projects will vary depending on the patterns of post-restoration flow, sediment supply and channel evolution.

  8. Channel dynamics and geomorphic resilience in an ephemeral Mediterranean river affected by gravel mining

    NASA Astrophysics Data System (ADS)

    Calle, Mikel; Alho, Petteri; Benito, Gerardo

    2017-05-01

    Gravel mining has been a widespread activity in ephemeral rivers worldwide whose long-lasting hydrogeomorphological impacts preclude effective implementation of water and environmental policies. This paper presents a GIS-based method for temporal assessment of morphosedimentary changes in relation to in-channel gravel mining in a typical ephemeral Mediterranean stream, namely the Rambla de la Viuda (eastern Spain). The aims of this work were to identify morphosedimentary changes and responses to human activities and floods, quantify river degradations and analyze factors favoring fluvial recovery for further applications in other rivers. Aerial photographs and LiDAR topography data were studied to analyze geomorphic evolution over the past 70 years along a 7.5-km reach of an ephemeral gravel stream that has been mined intensively since the 1970s. To evaluate changes in the riverbed, we mapped comparable units applying morphological, hydraulic, and stability (based on vegetation density and elevation) criteria to 13 sets of aerial photographs taken from 1946 to 2012. A detailed spatiotemporal analysis of comparable units revealed a 50% reduction in the active section and a 20% increase in stable areas, compared to the conditions observed prior to gravel mining. Instream mining was first observed in 1976 aerial photograph covering already up to 50% of the 1956 riverbed area. River degradation since then was quantified by means of a LiDAR DTM and RTK-GPS measurements, which revealed a 3.5-m incision that had started simultaneously with gravel mining. Climate and land use changes were present but the effects were completely masked by changes produced by instream gravel mining. Therefore, river incision/degradation was triggered by scarcity of sediment and lack of longitudinal sedimentary connection, creating an unbalanced river system that is still adjusting to the present hydrosedimentary conditions.

  9. Assessing potential abiotic and biotic complications of crayfish-induced gravel transport in experimental streams

    NASA Astrophysics Data System (ADS)

    Statzner, Bernhard; Peltret, Odile

    2006-03-01

    Biogeomorphology adds the element "biological dynamics" (of populations or communities) to chemical and physical geomorphic factors and thus complicates the framework of geomorphic processes. Such biological complications of the animal-induced transport of solids in streams should be particularly important in crayfish, as crayfish affect this transport through their overall activity and intraspecific aggression levels, which could be modified by shelter availability or the establishment of dominance hierarchies among individuals not knowing each other. Using experimental streams, we tested these hypotheses by measuring how shelter availability or residential crayfish group invasion by unknown individuals affected the impact of the crayfish Orconectes limosus on the (i) transport of gravel at baseflow (during 12 experimental days); (ii) sediment surface characteristics (after 12 days); and (iii) critical shear stress causing incipient gravel motion during simulated floods (after 12 days). The two potentially important factors shelter availability or residential group invasion negligibly affected the crayfish impact on gravel sediments, suggesting that habitat unfamiliarity (a third potentially important factor affecting crayfish activity) should increase the crayfish-induced sediment transport. Because habitat unfamiliarity is associated with sporadic long-distance migrations of a few crayfish individuals, this third factor should play a minor role in real streams, where crayfish biomass should be a key factor in relations with crayfish effects on sediments. Therefore, we combined the results of this study with those of previous crayfish experiments to assess how crayfish biomass could serve in modelling the gravel transport. Crayfish biomass explained 47% of the variability in the baseflow gravel transport and, in combination with the coefficient of variation of the bed elevation and algal cover, 72% of the variability in the critical gravel shear stress. These

  10. Effects of Surface and Subsurface Bed Material Composition on Gravel Transport and Flow Competence Relations—Possibilities for Prediction

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Bedload transport and flow competence relations are difficult to predict in coarse-bedded steep streams where widely differing sediment supply, bed stability, and complex flow hydraulics greatly affect amounts and sizes of transported gravel particles. This study explains how properties of bed material surface and subsurface size distributions are directly related to gravel transport and may be used for prediction of gravel transport and flow competence relations. Gravel transport, flow competence, and bed material size were measured in step-pool and plane-bed streams. Power functions were fitted to gravel transport QB=aQb and flow competence Dmax=cQd relations; Q is water discharge. Frequency distributions of surface FDsurf and subsurface FDsub bed material were likewise described by power functions FDsurf=hD j and FDsub=kDm fitted over six 0.5-phi size classes within 4 to 22.4 mm. Those gravel sizes are typically mobile even in moderate floods. Study results show that steeper subsurface bed material size distributions lead to steeper gravel transport and flow competence relations, whereas larger amounts of sediment contained in those 6 size bedmaterial classes (larger h and k) flatten the relations. Similarly, steeper surface size distributions decrease the coefficients of the gravel transport and flow competence relations, whereas larger amounts of sediment within the six bed material classes increase the intercepts of gravel transport and flow competence relations. Those relations are likely causative in streams where bedload stems almost entirely from the channel bed as opposed to direct (unworked) contributions from hillslopes and tributaries. The exponent of the subsurface bed material distribution m predicted the gravel transport exponent b with r2 near 0.7 and flow competence exponent d with r2 near 0.5. The intercept of bed surface distributions h increased the intercept a of gravel transport and c of the flow competence relations with r2 near 0.6.

  11. Several 1992 astronaut candidates brush the sand and gravel off one another following one of several

    NASA Technical Reports Server (NTRS)

    1992-01-01

    1992 ASCAN TRAINING --- Several 1992 astronaut candidates brush the sand and gravel off one another following one of several phases of parachute familiarization and survival training at Vance Air Force Base in Oklahoma. Recognizable in the picture are Wendy B. Lawrence, Michael E. Lopez-Alegria, Chris A. Hadfield, Winston E. Scott and Koichi Wakata. The trainees had just completed an exercise which required their jumping off a box into a gravel pit, in order to familiarize them the proper way to meet the ground following an emergency parachute drop.

  12. Hydrology of the sand-and-gravel aquifer, southern Okaloosa and Walton Counties, northwest Florida

    USGS Publications Warehouse

    Hayes, L.R.; Barr, D.E.

    1982-01-01

    The sand-and-gravel aquifer in southern Okaloosa and Walton Counties, northwest Florida, extends from land surface to depth of 50 to 150 feet. Intervening layers of clay generally separate the aquifer into an unconfined surficial zone, composed principally of fine to medium sand, and a lower confined zone, consisting of variable amounts of medium to coarse sand and gravel. Well yields of 50 to 500 gallons per minute are possible in most of the area, and yields of 500 to 1,000 gallons per minute can be developed in parts of southwestern Okaloosa County. (USGS)

  13. Kinetic analysis of strontium and potassium sorption onto sands and gravels in a natural channel.

    USGS Publications Warehouse

    Bencala, K.E.; Jackman, A.P.; Kennedy, V.C.; Avanzino, R.J.; Zellweger, G.W.

    1983-01-01

    A kinetic, first-order mass transfer model was used to describe the sorption of strontium onto sand-and gravel-sized streambed sediments. Rate parameters, empirically determined for strontium, allowed for the prediction of potassium sorption with moderate success. The model parameters varied significantly with particle size. The sorption data were collected during an experimental injection of several elements into a small mountain pool-and- riffle stream. The sorption process onto sand- and gravel-sized sediment was relatively slow compared to changes in the dissolved concentrations. -Authors

  14. Map showing gravel-bearing surficial deposits and basaltic rocks near Trinidad, Las Animas County, Colorado

    USGS Publications Warehouse

    Scott, Glenn R.

    1985-01-01

    This map of the Trinidad area is considered to be a special purpose map, as it shows only gravel-bearing alluvial deposits laid down by streams and a series of stacked lava flows erupted from local volcanoes.  Nongravelly surficial deposits and Cretaceous bedrock, which would be on a standard geologic map, are not shown.  The map has two purposes: a scientific one to show the distribution, character, and age of the alluvial deposits and a practical one, to map the distribution of deposits of gravel and crushable rock for use as construction materials.

  15. Propagation of sediment pulses in flume experiments simulating gravel augmentation in armored channels downstream of dams

    NASA Astrophysics Data System (ADS)

    Fadde, J.; Venditti, J. G.; Sklar, L. S.; Wydzga, A.; Nelson, P. A.; Dietrich, W. E.

    2005-12-01

    Gravel augmentation is an increasingly common river restoration strategy for armored channels downstream of dams, however, few analytical tools are available to assist river managers in selecting the appropriate sediment volumes, grain sizes, and frequency of additions to achieve desired geomorphic and ecological outcomes. Coarse sediment additions are often intended to improve habitat for spawning salmonids by altering stream bed grain size distributions, and increasing the frequency of bed mobilization and the diversity of channel morphology. Here we report preliminary results of an ongoing laboratory investigation in which we simulate the gravel augmentation process and document the spatial and temporal evolution of the bed in response to pulses of elevated fine gravel supply. The experiments are conducted in a 30-m long, 0.86-m wide flume, with a calibrated sediment feed and a tipping bucket type sediment trap that provides a continuous record of sediment flux at the downstream end of the flume. We created an initial armored bed by first achieving an active transport equilibrium slope and then shutting off the sediment feed and allowing the bed to coarsen and degrade until the transport rate became negligible. We then introduced gravel pulses of various volumes and grain sizes, and mapped the propagation of the wave of added sediment as it moved through the flume. The sediments comprising each pulse are painted distinct colors to aid in mapping and to quantify the extent of exchange with the armored bed. Mapping techniques include planform maps of zones of active transport and temporal contours of width-averaged concentrations of added gravel. We also documented the changes in bed grain size distribution using manual pebble counts before and after each run and analysis of high resolution photographs of the bed taken during the run. We also collected frequent bedload samples at regular locations along the flume length to document the movement of the gravel pulse

  16. Groundwater and surface water interaction in flow-through gravel pit lakes.

    NASA Astrophysics Data System (ADS)

    Nella Mollema, Pauline; Antonellini, Marco

    2015-04-01

    Gravel pits are excavated in aquifers to fulfill the need for construction materials. Flow-through lakes form when the gravel pits are below the water table and fill with groundwater. In certain areas there are more than 60 of these lakes close together and their presence changes the drainage patterns and water- and hydrochemical budgets of a watershed. In flow-through gravel pit lakes, groundwater mixes with surface water and interacts with the atmosphere; outflow occurs only via groundwater. The lifespan of gravel pit lakes may be up to thousands of years as their depth to surface ratio is typically large and sedimentation rates are low. We have studied two gravel pit lake systems, a fluvial freshwater system in the Netherlands and a coastal brackish lake system in Italy. One Dutch gravel pit lake studied in detail is in part artificially replenished with Meuse River water for drinking water production that occurs downstream of the lake by water pumps. The Italian gravel pit lakes are fed by brackish groundwater that is a mix of freshwater from precipitation, Apennine Rivers and brackish (Holocene) Adriatic Sea water. Here, the drainage system of the low lying land enhances groundwater flow into the lake. Surface water evaporation is larger in temperate and Mediterranean climates than the actual evapotranspiration of pre-existing grassland and forests. The lakes, therefore, cause a loss of freshwater. The creation of water surfaces allows algae and other flora and fauna to develop. In general, water becomes gradually enriched in certain chemical constituents on its way through the hydrological cycle, especially as groundwater due to water-rock interactions. When groundwater ex-filtrates into gravel pit lakes, the natural flow of solutes towards the sea is interrupted. Hydrochemical analysis of ground- and surface waters, as well as chemical analysis of lake bottom sediments and stable H and O isotope data, show that gravel pit lake water is characterized (among

  17. 32 CFR 644.551 - Equal opportunity-sales of timber, embedded sand, gravel, stone, and surplus structures.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 4 2011-07-01 2011-07-01 false Equal opportunity-sales of timber, embedded sand... § 644.551 Equal opportunity—sales of timber, embedded sand, gravel, stone, and surplus structures...) Sale of standing timber. (b) Sale of embedded sand, gravel, and stone in their natural state. (c) Sale...

  18. 32 CFR 644.551 - Equal opportunity-sales of timber, embedded sand, gravel, stone, and surplus structures.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 4 2010-07-01 2010-07-01 true Equal opportunity-sales of timber, embedded sand... § 644.551 Equal opportunity—sales of timber, embedded sand, gravel, stone, and surplus structures...) Sale of standing timber. (b) Sale of embedded sand, gravel, and stone in their natural state. (c)...

  19. Resistivity Profiling for Mapping Gravel Layers That May Control Contaminant Migration at the Amargosa Desert Research Site, Nevada

    USGS Publications Warehouse

    Lucius, Jeffrey E.; Abraham, Jared D.; Burton, Bethany L.

    2008-01-01

    Gaseous contaminants, including CFC 113, chloroform, and tritiated compounds, move preferentially in unsaturated subsurface gravel layers away from disposal trenches at a closed low-level radioactive waste-disposal facility in the Amargosa Desert about 17 kilometers south of Beatty, Nevada. Two distinct gravel layers are involved in contaminant transport: a thin, shallow layer between about 0.5 and 2.2 meters below the surface and a layer of variable thickness between about 15 and 30 meters below land surface. From 2003 to 2005, the U.S. Geological Survey used multielectrode DC and AC resistivity surveys to map these gravel layers. Previous core sampling indicates the fine-grained sediments generally have higher water content than the gravel layers or the sediments near the surface. The relatively higher electrical resistivity of the dry gravel layers, compared to that of the surrounding finer sediments, makes the gravel readily mappable using electrical resistivity profiling. The upper gravel layer is not easily distinguished from the very dry, fine-grained deposits at the surface. Two-dimensional resistivity models, however, clearly identify the resistive lower gravel layer, which is continuous near the facility except to the southeast. Multielectrode resistivity surveys provide a practical noninvasive method to image hydrogeologic features in the arid environment of the Amargosa Desert.

  20. 32 CFR 644.551 - Equal opportunity-sales of timber, embedded sand, gravel, stone, and surplus structures.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., gravel, stone, and surplus structures. 644.551 Section 644.551 National Defense Department of Defense... § 644.551 Equal opportunity—sales of timber, embedded sand, gravel, stone, and surplus structures... of surplus structures where an appreciable amount of dismantling and site restoration is involved. ...

  1. 32 CFR 644.551 - Equal opportunity-sales of timber, embedded sand, gravel, stone, and surplus structures.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., gravel, stone, and surplus structures. 644.551 Section 644.551 National Defense Department of Defense... § 644.551 Equal opportunity—sales of timber, embedded sand, gravel, stone, and surplus structures... of surplus structures where an appreciable amount of dismantling and site restoration is involved. ...

  2. 32 CFR 644.551 - Equal opportunity-sales of timber, embedded sand, gravel, stone, and surplus structures.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 4 2014-07-01 2013-07-01 true Equal opportunity-sales of timber, embedded sand... § 644.551 Equal opportunity—sales of timber, embedded sand, gravel, stone, and surplus structures...) Sale of standing timber. (b) Sale of embedded sand, gravel, and stone in their natural state. (c) Sale...

  3. The volume of fine sediment in pools: An index of sediment supply in gravel-bed streams

    Treesearch

    Thomas E. Lisle; Sue Hilton

    1992-01-01

    Abstract - During waning flood flows in gravel-bed streams, fine-grained bedload sediment (sand and fine gravel) is commonly winnowed from zones of high shear stress, such as riffles, and deposited in pools, where it mantles an underlying coarse layer. As sediment load increases, more fine sediment becomes availabe to fill pools. The volume of fine sediment in pools...

  4. Basin-scale availability of salmonid spawning gravel as influenced by channel type and hydraulic roughness in mountain catchments.

    Treesearch

    John M. Buffington; David R. Montgomery; Harvey M. Greenberg

    2004-01-01

    A general framework is presented for examining the effects of channel type and associated hydraulic roughness on salmonid spawning-gravel availability in mountain catchments. Digital elevation models are coupled with grain-size predictions to provide basin-scale assessments of the potential extent and spatial pattern of spawning gravels. To demonstrate both the model...

  5. Response of bed mobility to sediment supply in natural gravel bed channels: A detailed examination and evaluation of mobility parameters

    Treesearch

    T. E. Lisle; J. M. Nelson; B. L. Barkett; J. Pitlick; M. A. Madej

    1998-01-01

    Recent laboratory experiments have shown that bed mobility in gravel bed channels responds to changes in sediment supply, but detailed examinations of this adjustment in natural channels have been lacking, and practical methodologies to measure bed mobility have not been tested. We examined six gravel-bed, alternate-bar channels which have a wide range in annual...

  6. Predicting bed load transport of sand and gravel on Goodwin Creek

    USDA-ARS?s Scientific Manuscript database

    Bed load transport rates are difficult to predict in channels with bed material composed of sand and gravel mixtures. The transport of bed load was measured on Goodwin Creek, and in a laboratory flume channel with a similar bed material size distribution. The range of bed load transport rates meas...

  7. Alba Field cased hole horizontal gravel pack -- A team approach to design

    SciTech Connect

    Alexander, K.; Winton, S.; Price-Smith, C.

    1995-12-31

    A 700 ft. cased hole horizontal well was gravel packed and completed in the Alba Field, Central North Sea. The completion incorporated a number of new technologies adopted for a horizontal cased hole completion including both equipment and fluids. The zone was completed in 2 stages using a horizontal stack pack approach. Perforation packing was optimized by performing a staged acid prepack with the guns in the hole utilizing a low density synthetic gravel substitute in a shear thinning carrier fluid. This was a world first achievement at a cased hole gravel pack using the stack pack approach in a horizontal well. A solids free fluid loss control material was evaluated and chosen for the high permeability Alba sands (3 Darcy). Extensive lab testing was performed to ensure minimal damage from various fluids. A 30 ft. physical model was used to optimize annular pack efficiency. A gravel placement computer simulation was used to design pump rate, sand concentration and gel loading in order to optimize annular and perforation pack efficiency.

  8. Alba Field cased-hole horizontal gravel pack: A team approach to design

    SciTech Connect

    Alexander, K.; Winton, S.; Price-Smith, C.

    1996-03-01

    A 700-ft cased-hole horizontal well was gravel packed and completed in the Alba Field, central North Sea. The completion incorporated a number of new technologies adopted for a horizontal cased-hole completion, including both equipment and fluids. The zone was completed in two stages using a horizontal stack-pack approach. Perforation packing was optimized by performing a staged acid prepack with the guns in the hole using a low-density synthetic gravel substitute in a shear thinning carrier fluid. This was a world-first achievement at a cased-hole gravel pack using the stack-pack approach in a horizontal well. A solids-free fluid-loss control material was evaluated and chosen for the high-permeability Alba sands (3 darcies). Extensive lab testing was performed to ensure minimal damage from various fluids. A 30-ft physical model was used to optimize annular pack efficiency. A gravel placement computer simulation was used to design pump rate, sand concentration, and gel loading to optimize annular and perforation-pack efficiency.

  9. Alba field cased hole horizontal gravel pack -- a team approach to design

    SciTech Connect

    Alexander, K.; Winton, S.; Price-Smith, C.

    1995-12-31

    A 700 ft cased hole horizontal well was gravel packed and completed in the Alba Field, Central North Sea. The completion incorporated a number of new technologies adopted for a horizontal cased hole completion including both equipment and fluids. The zone was completed in 2 stages using a horizontal stack pack approach. Perforation packing was optimized by performing a staged acid prepack with the guns in the hole utilizing a low density synthetic gravel substitute in a shear thinning carrier fluid. This was a world first achievement at a cased hole gravel pack using the stack pack approach in a horizontal well. A solids free fluid loss control material was evaluated and chosen for the high permeability Alba Sands (3 Darcy). Extensive lab testing was performed to ensure minimal damage from various fluids. A 30 ft physical model was used to optimize annular pack efficiency. A gravel placement computer simulation was used to design pump rate, sand concentration and gel loading in order to optimize annular and perforation pack efficiency.

  10. Correction to "A general power equation for predicting bed load transport rates in gravel bed rivers"

    Treesearch

    Jeffrey J. Barry; John M. Buffington; John G. King

    2007-01-01

    In the paper "A general power equation for predicting bed load transport rates in gravel bed rivers" by Jeffrey J. Barry et al. (Water Resources Research, 40, W10401, doi:10.1029/2004WR003190, 2004), the y axis for Figures 5 and 10 was incorrectly labeled and should have read "log10 (predicted transport) - log10 (observed transport)." In addition,...

  11. Sediment transport primer: estimating bed-material transport in gravel-bed rivers

    Treesearch

    Peter Wilcock; John Pitlick; Yantao Cui

    2009-01-01

    This primer accompanies the release of BAGS, software developed to calculate sediment transport rate in gravel-bed rivers. BAGS and other programs facilitate calculation and can reduce some errors, but cannot ensure that calculations are accurate or relevant. This primer was written to help the software user define relevant and tractable problems, select appropriate...

  12. An Experimental Study of Sand Transport over an Immobile Gravel Substrate

    USDA-ARS?s Scientific Manuscript database

    The effects of a stepwise addition of sand to an immobile gravel bed on the sand transport rate and configuration of the sand bed was investigated in a laboratory flume channel. Detailed measurements of sand transport rate, bed texture, and bed topography were collected for four different discharge...

  13. Effects of hydraulic roughness on surface textures of gravel-bed rivers

    Treesearch

    John M. Buffington; David R. Montgomery

    1999-01-01

    Field studies of forest gravel-bed rivers in northwestern Washington and southeastern Alaska demonstrate that bed-surface grain size is responsive to hydraulic roughness caused by bank irregularities, bars, and wood debris. We evaluate textural response by comparing reach-average median grain size (D50) to that predicted from the total bank-full boundary shear stress (...

  14. A procedure for classifying textural facies in gravel-bed rivers

    Treesearch

    John M. Buffington; David R. Montgomery

    1999-01-01

    Textural patches (i.e., grain-size facies) are commonly observed in gravel-bed channels and are of significance for both physical and biological processes at subreach scales. We present a general framework for classifying textural patches that allows modification for particular study goals, while maintaining a basic degree of standardization. Textures are classified...

  15. Experiments on the effect of hydrograph characteristics on vertical grain sorting in gravel bed rivers

    NASA Astrophysics Data System (ADS)

    Hassan, Marwan A.; Egozi, Roey; Parker, Gary

    2006-09-01

    Desert ephemeral gravel bed streams typically have bed surfaces that are relatively unarmored compared to the substrate below, while gravel bed streams in humid and snowmelt areas typically have well-armored surfaces. The degree of armoring can be characterized in terms of an armor ratio defined as the ratio of the surface median size to the substrate median size. A set of field data shows desert ephemeral gravel bed streams with armor ratios ranging from 0.5 to 2.4 and with an average value of 1.2. The armor ratio of snowmelt-fed gravel bed streams in the same set ranges from 2 to 7, with an average value of 3.4. The reason for this difference is sought in terms of differing hydrological characteristics and sediment supply regimes. Thirteen experiments were conducted to study the formation of armoring under a range of hydrological conditions. The experiments have two limiting cases: a relatively flat hydrograph that represents conditions produced by continuous snowmelt and a sharply peaked hydrograph that represents conditions associated with flash floods. All constant hydrograph experiments developed a well-armored structured surface, while short asymmetrical hydrographs did not result in substantial vertical sorting. All symmetrical hydrographs show some degree of sorting, and the sorting tended to become more pronounced with longer duration. Sediment supply appears to be a first-order control on bed surface armoring, while the shape of the hydrograph plays a secondary role.

  16. The dominance of dispersion in the evolution of bed material waves in gravel-bed rivers

    Treesearch

    Thomas E. Lisle; Yantao Cui; Gary Parker; James E. Pizzuto; Annjanette M. Dodd

    2001-01-01

    Abstract - Bed material waves are temporary zones of sediment accumulation created by large sediment inputs. Recent theoretical, experimental and field studies examine factors in fluencing dispersion and translation of bed material waves in quasi-uniform, gravel-bed channels. Exchanges of sediment between a channel and its floodplain are...

  17. Treatment performance of gravel filter media: implications for design and application of stormwater infiltration systems.

    PubMed

    Hatt, Belinda E; Fletcher, Tim D; Deletic, Ana

    2007-06-01

    Stormwater infiltration systems are widely used to address the flow and water quality impacts of urbanization. However, their pollutant removal performance is uncertain, with respect to varying filter depth, and over time. Seven simulation experiments were conducted on a laboratory-scale gravel infiltration system to test the pollutant removal under a range of water level regimes, including both constant and variable water levels. Gravel filters were found to be very effective for removal of sediment and heavy metals under all water level regimes, even as the system clogged over time. Despite the sediment particle size distribution being much smaller than the filter media pore size, sediment and its associated pollutants were effectively trapped in the top of the gravel filter, even when the water level was allowed to vary. A media depth of 0.5 m was found to achieve adequate pollutant removal. Breakthrough of pollutants may not be of concern, since physical clogging occurred first (thus determining the lifespan of the filter media). However, gravel filters were less effective at nutrient removal, particularly for dissolved nutrients.

  18. Coupling fine particle and bedload transport in gravel-bedded streams

    NASA Astrophysics Data System (ADS)

    Park, Jungsu; Hunt, James R.

    2017-09-01

    Fine particles in the silt- and clay-size range are important determinants of surface water quality. Since fine particle loading rates are not unique functions of stream discharge this limits the utility of the available models for water quality assessment. Data from 38 minimally developed watersheds within the United States Geological Survey stream gauging network in California, USA reveal three lines of evidence that fine particle release is coupled with bedload transport. First, there is a transition in fine particle loading rate as a function of discharge for gravel-bedded sediments that does not appear when the sediment bed is composed of sand, cobbles, boulders, or bedrock. Second, the discharge at the transition in the loading rate is correlated with the initiation of gravel mobilization. Third, high frequency particle concentration and discharge data are dominated by clockwise hysteresis where rising limb discharges generally have higher concentrations than falling limb discharges. These three observations across multiple watersheds lead to a conceptual model that fine particles accumulate within the sediment bed at discharges less than the transition and then the gravel bed fluidizes with fine particle release at discharges above the transition discharge. While these observations were individually recognized in the literature, this analysis provides a consistent conceptual model based on the coupling of fine particle dynamics with filtration at low discharges and gravel bed fluidization at higher discharges.

  19. Preliminary Assessment of Vertical Stability and Gravel Transport along the Umpqua River, Southwestern Oregon

    USGS Publications Warehouse

    O'Connor, Jim E.; Wallick, J. Rose; Sobieszczyk, Steven; Cannon, Charles; Anderson, Scott W.

    2009-01-01

    This report addresses physical channel issues related to instream gravel mining on the Umpqua River and its two primary tributaries, the North and South Umpqua Rivers. This analysis constitutes a 'Phase I' investigation, as designated by an interagency team cochaired by the U.S. Army Corps of Engineers, Portland District, and the Oregon Department of State Lands to address instream gravel mining issues across Oregon. Phase I analyses rely primarily on existing datasets and cursory analysis to determine the vertical stability of a channel to ascertain whether a particular river channel is aggrading, degrading, or at equilibrium. Additionally, a Phase I analysis identifies other critical issues or questions pertinent to physical channel conditions that may be related to instream gravel mining activities. This analysis can support agency permitting decisions as well as possibly indicating the need for additional studies. This specific analysis focuses on the mainstem Umpqua River from the Pacific Ocean at River Mile (RM) 0 to the confluence of the North and South Umpqua Rivers (at RM 111.8), as well as the lower 29 mi of the North Umpqua River and the lower 80 mi of the South Umpqua River (fig. 1). It is within these reaches where mining of gravel bars for aggregate has been most prevalent.

  20. The geomorphic response of gravel-bed rivers to dams: perspectives and prospects

    Treesearch

    Gordon E. Grant

    2012-01-01

    The paper summarizes over 40 years of research on the downstream geomorphic responses of rivers to dams, with a particular emphasis on gravel-bed rivers, and evaluates the state if the science with respect to predicting channel adjustments: channel incision, lateral adjustments, and bed textural changes. Effects of vegetation and implications for management are also...

  1. Settlement with Stone Crushing and Gravel Company will Help Reduce Emissions

    EPA Pesticide Factsheets

    A company running a stone-crushing and gravel processing facility in Westerly, R.I. has taken steps to help minimize emissions of hazardous air pollutants and visually test for dust under an agreement signed recently with the U.S. EPA.

  2. Particle size variations between bed load and bed material in natural gravel bed channels

    Treesearch

    Thomas E. Lisle

    1995-01-01

    Abstract - Particle sizes of bed load and bed material that represent materials transported and stored over a period of years are used to investigate selective transport in 13 previously sampled, natural gravel bed channels. The ratio (D*) of median particle size of bed material to the transport- and frequency-weighted mean of median bed load size decreases to unity...

  3. Measuring pebble abrasion on a mixed sand and gravel beach using abrasion baskets

    NASA Astrophysics Data System (ADS)

    Chen, Bin; Stephenson, Wayne

    2015-11-01

    The abrasion of sediments on mixed sand and gravel beaches has important consequences for local sediment budgets as abrasion often accounts for the major loss of beach volume. Here we report an innovative method using abrasion baskets to measure abrasion in the swash zone of mixed sand and gravel beaches. This method offers significant advantages over laboratory-based tumbler experiments traditionally used to determine abrasion rates. The very high recovery rate from our method is also a significant advantage over previous field methods using radio frequency identification technology to measure abrasion where tagged particles are often lost. Either three or five abrasion baskets were placed across the swash zone on a mixed sand and gravel beach at Timaru, South Island, New Zealand, to measure the abrasion occurring on labeled sediments placed in the baskets. Over two experiments, results showed measurable abrasion across the swash zone with higher abrasion rates occurring in the middle of the swash zone and lower rates towards the swash limit and at the breaker zone. Results also illustrate the role of changing wave energy on abrasion loss. A relationship between particle size and abrasion rate was also found, similar to previous laboratory results reported in the literature. Our preliminary experiments lead us to define an abrasion zone and this idea may help shape future research on abrasion processes on mixed sand and gravel beaches.

  4. Effects of sediment supply on surface textures of gravel-bed rivers

    Treesearch

    John M. Buffington; David R. Montgomery

    1999-01-01

    Using previously published data from flume studies, we test a new approach for quantifying the effects of sediment supply (i.e., bed material supply) on surface grain size of equilibrium gravel channels. Textural response to sediment supply is evaluated relative to a theoretical prediction of competent median grain size (D’50). We find that surface median grain size (...

  5. TRANSPORT OF CHROMIUM AND SELENIUM IN A PRISTINE SAND AND GRAVEL AQUIFER: ROLE OF ADSORPTION PROCESSES

    EPA Science Inventory

    Field transport experiments were conducted in an oxic sand and gravel aquifer using Br (bromide ion), Cr (chromium, injected as Cr(VI)), Se (selenium, injected as Se(VI)), and other tracers. The aquifer has mildly acidic pH values and low concentrations of dissolved salts. Within...

  6. TRANSPORT OF CHROMIUM AND SELENIUM IN A PRISTINE SAND AND GRAVEL AQUIFER: ROLE OF ADSORPTION PROCESSES

    EPA Science Inventory

    Field transport experiments were conducted in an oxic sand and gravel aquifer using Br (bromide ion), Cr (chromium, injected as Cr(VI)), Se (selenium, injected as Se(VI)), and other tracers. The aquifer has mildly acidic pH values and low concentrations of dissolved salts. Within...

  7. Turbulence measurements over immobile gravel with additions of sand from supply limited to capacity transport conditions

    USDA-ARS?s Scientific Manuscript database

    Measurement of the turbulence that drives sand transport over and through immobile gravels is relevant to efforts to model sediment movement downstream of dams, where fine sediments are eroded from coarse substrates and are not replaced due to the presence of the upstream dam. The relative elevatio...

  8. Performance of bed load transport equations in mountain gravel-bed rivers: A re-analysis

    Treesearch

    Jeffrey J. Barry; John M. Buffington; John G. King; Peter Goodwin

    2006-01-01

    Our recent examination of bed load transport data from mountain gravel-bed rivers in the western United States shows that the data can be fit by a simple power function of discharge, with the coefficient being a function of drainage area (a surrogate for basin sediment supply) and the exponent being a function of supply-related channel armoring (transport capacity in...

  9. Flume experiment based analysis of fine sediment infiltration into gravel-beds

    NASA Astrophysics Data System (ADS)

    Lamparter, Gabriele; Nicolas, Andrew; Collins, Adrian; Michaelides, Katerina

    2010-05-01

    Gravel bed rivers provide valuable habitat for a multitude of organisms, many of which are dependent on the porous nature of the river substrate (eg. insect larvae and salmonids eggs). Agricultural land use and other anthropogenic activities can lead to increased fine sediment delivery to water courses and associated fine sediment infiltration into the gravel bed, promoting clogging of pore space and habitat degradation. This problem is well established. However, current quantitative understanding of the processes involved remains poor. Here we report the results from a series of laboratory flume experiments designed to illuminate the mechanisms controlling the infiltration, deposition and remobilisation of fine sediments within gravel bed rivers. Experiments were carried out in a 10 m long, 0.6 m wide flume with a 0.2 m thick gravel bed. Data were collected to quantify variations in mean velocity, turbulence characteristics, fine sediment concentration and composition, bed roughness and bed substrate. Rates and patterns of fine sediment storage were quantified using sediment traps placed within the bed substrate, and by continuous monitoring of suspended sediment concentration within the water column. Fine sediment was analysed to determine the size distribution of both the suspended particles (including flocs and aggregates) and the primary particles of which they are composed. Turbulent velocity profiles were obtained above each of the sediment traps using an array of ADVs (Acoustic Doppler Velocimeters). Flume data are used to test a multiple size class suspended sediment transport model suitable for future application in natural rivers.

  10. Unifying criterion for the velocity reversal hypothesis in gravel-bed rivers

    Treesearch

    Diego Caamano; Peter Goodwin; John M. Buffington; Jim C. P. Liou; Stanley Daley-Laursen

    2009-01-01

    It has been hypothesized that velocity reversals provide a mechanism for maintaining pool-riffle morphology in gravel-bed rivers-an important habitat for salmonids, which are at risk in many places worldwide and that are the focus of extensive environmental legislation in Europe and North America. However, the occurrence of velocity reversals has been controversial for...

  11. Stabilization of a gravel channel by large streamside obstructions and bedrock bends, Jacoby Creek, northwestern California

    Treesearch

    Thomas E. Lisle

    1996-01-01

    Abstract - Jacoby Creek (bed width =12 m; bankfull discharge = 32.6 m 3 /s) contains stationary gravel bars that have forms and positions controlled by numerous large streamside obstructions (bedrock outcrops, large woody debris, and rooted bank projections) and bedrock bends. Bank-projection width and bar volume measured in 104 channel segments 1 bed-width long are...

  12. An Investigation into the Processes and Quantity of Dust Emissions over Gravel and Sand Deserts in North-Western China

    NASA Astrophysics Data System (ADS)

    Zhang, Zhengcai; Dong, Zhibao; Qian, Guangqian; Wu, Guoxi; Cui, Xujia

    2017-01-01

    Year-long field observations have shown that there are spatial and temporal variations in the quantity of dust emissions for particulate matter {<} 10 μm (PM10), particulate matter {<} 63 μm (PM63) and vertical dust flux over different gravel surfaces (with loose sand, without loose sand, with a crust, and without a crust), with the greatest emissions occurring in the spring. The largest quantity of PM10 and PM63 emissions occurred over gravel with a loose sand surface (1.1 × 10^{-3} and 10.2 × 10^{-3} kg m^{-1} day^{-1} , respectively). The gravel surface without loose sand and without a crust presents the lowest values of PM63 (1.6 × 10^{-3} kg m^{-1} day^{-1} ) and PM10 (3.3 × 10^{-4}{ kg m^{-1} day^{-1} ). However, the vertical dust flux was largest at over sandy surface (373 × 10^{-3} kg m^{-2} day^{-1} ). Multivariate correlation analysis indicates that the quantity of PM10 is strongly negatively correlated to gravel coverage (R^{2 }= 0.55 ). The quantity of PM10 dust emissions over a gravel surface with loose sand is approximately three times greater than that of a gravel surface with a crust. The mean quantity of PM10, PM63 and vertical dust flux over a gravel surface decreased with increasing gravel coverage. By comparing the quantity of PM10 dust emissions over gravel and sandy deserts, we found that gravel deserts and sandy deserts are both major sources of dust for dust storms in this region.

  13. An Investigation into the Processes and Quantity of Dust Emissions over Gravel and Sand Deserts in North-Western China

    NASA Astrophysics Data System (ADS)

    Zhang, Zhengcai; Dong, Zhibao; Qian, Guangqian; Wu, Guoxi; Cui, Xujia

    2017-06-01

    Year-long field observations have shown that there are spatial and temporal variations in the quantity of dust emissions for particulate matter {<}10 μm (PM10), particulate matter {<}63 μm (PM63) and vertical dust flux over different gravel surfaces (with loose sand, without loose sand, with a crust, and without a crust), with the greatest emissions occurring in the spring. The largest quantity of PM10 and PM63 emissions occurred over gravel with a loose sand surface (1.1 × 10^{-3} and 10.2 × 10^{-3} kg m^{-1} day^{-1}, respectively). The gravel surface without loose sand and without a crust presents the lowest values of PM63 (1.6 × 10^{-3} kg m^{-1} day^{-1}) and PM10 (3.3 × 10^{-4} kg m^{-1} day^{-1}). However, the vertical dust flux was largest at over sandy surface (373 × 10^{-3 } kg m^{-2} day^{-1}). Multivariate correlation analysis indicates that the quantity of PM10 is strongly negatively correlated to gravel coverage (R^{2 }= 0.55). The quantity of PM10 dust emissions over a gravel surface with loose sand is approximately three times greater than that of a gravel surface with a crust. The mean quantity of PM10, PM63 and vertical dust flux over a gravel surface decreased with increasing gravel coverage. By comparing the quantity of PM10 dust emissions over gravel and sandy deserts, we found that gravel deserts and sandy deserts are both major sources of dust for dust storms in this region.

  14. Modeling flows over gravel beds by a drag force method and a modified S-A turbulence closure

    NASA Astrophysics Data System (ADS)

    Zeng, C.; Li, C. W.

    2012-09-01

    A double-averaged Navier-Stokes equations (DANS) model has been developed for depth-limited open channel flows over gravels. Three test cases are used to validate the model: an open-channel flow over a densely packed gravel bed with small-scale uniform roughness (D/d50 ˜ 13, d50 = median diameter of roughness elements, D = water depth), open-channel flows over large-scale sparsely distributed roughness elements (D/Δ ˜ 2.3-8.7, Δ = roughness height) and steep slope gravel-bed river flows with D/d50 ˜ 7-25. Various methods of treatment of the gravel-induced resistance effect have been investigated. The results show that the wall function approach (WFA) is successful in simulating flows over small gravels but is not appropriate for large gravels since the vertical profile of the longitudinal velocity does not follow the logarithmic-linear relationship. The drag force method (DFM) performs better but the non-logarithmic velocity distribution generated by sparsely distributed gravels cannot be simulated accurately. Noting that the turbulence length scale within the gravel layer is governed by the gravel size, the DANS model incorporating the DFM and a modified Spalart-Allmaras (S-A) turbulence closure is proposed. The turbulence length scale parameter in the S-A model is modified to address the change in the turbulence structure within the gravel layer. The computed velocity profiles agree well with the corresponding measured profiles in all cases. Particularly, the model reproduces the S-shape velocity profile for sparsely distributed large size roughness elements. The modeling methodology is robust and can be easily integrated into the existing numerical models.

  15. Estimated sand and gravel resources of the South Merrimack, Hillsborough County, New Hampshire, 7.5-minute quadrangle

    USGS Publications Warehouse

    Sutphin, D.M.; Drew, L.J.; Fowler, B.K.

    2006-01-01

    A computer methodology is presented that allows natural aggregate producers, local governmental, and nongovernmental planners to define specific locations that may have sand and gravel deposits meeting user-specified minimum size, thickness, and geographic and geologic criteria, in areas where the surficial geology has been mapped. As an example, the surficial geologic map of the South Merrimack quadrangle was digitized and several digital geographic information system databases were downloaded from the internet and used to estimate the sand and gravel resources in the quadrangle. More than 41 percent of the South Merrimack quadrangle has been mapped as having sand and (or) gravel deposited by glacial meltwaters. These glaciofluvial areas are estimated to contain a total of 10 million m3 of material mapped as gravel, 60 million m3 of material mapped as mixed sand and gravel, and another 50 million m3 of material mapped as sand with minor silt. The mean thickness of these areas is about 1.95 meters. Twenty tracts were selected, each having individual areas of more than about 14 acres4 (5.67 hectares) of stratified glacial-meltwater sand and gravel deposits, at least 10-feet (3.0 m) of material above the watertable, and not sterilized by the proximity of buildings, roads, streams and other bodies of water, or railroads. The 20 tracts are estimated to contain between about 4 and 10 million short tons (st) of gravel and 20 and 30 million st of sand. The five most gravel-rich tracts contain about 71 to 82 percent of the gravel resources in all 20 tracts and about 54-56 percent of the sand. Using this methodology, and the above criteria, a group of four tracts, divided by narrow areas sterilized by a small stream and secondary roads, may have the highest potential in the quadrangle for sand and gravel resources. ?? Springer Science+Business Media, LLC 2006.

  16. Transient and steady State Patterns in Gravel Bars Following Sediment Supply Increases

    NASA Astrophysics Data System (ADS)

    Podolak, C.; Wilcock, P.

    2011-12-01

    Bedforms in a gravel-bed river respond to a combination of water discharge, sediment supply, and valley-scale geometry. The bed configuration can also vary between transient and steady-state conditions. Field and flume observations of gravel bedform responses to changes in sediment supply have focused primarily on decreased sediment supply, and those that have dealt with increased sediment supply have found cases of both increasing relief and decreasing relief. We present gravel bedform configurations under conditions of increased sediment supply in both field and laboratory conditions. The field study tracked the response of the Sandy River, Oregon after an increase in sediment flux due to the 2007 Marmot Dam removal in which nearly 750,000 m3 of impounded sediment which was made available for transport and resulted in a several-fold increase in annual sediment flux. The flume experiments introduced perturbation in a planar gravel bed (gravel D50 = 10mm, 15% sand) prompting alternate bar formation. Sediment was then manually added to the recirculating flume (in essence operating it as a feed flume) increasing flux rates by 50%. Upon reaching a steady state, the upstream flux was then augmented again to double the steady state rate. In response to the increased sediment supply the bed topography steepened to transport the imposed sediment flux. In both flume and field, the final bed response to increased sediment supply was deposition of a sediment wedge, steeping the channel slope with little change in bar morphology. Although the location and morphology of the bedforms were similar as the bed configuration stabilized, the transient response showed different patterns of deposition across the stream. A pattern of decreasing relief both from bar tops eroding and pools filling was observed as well as the migration of smaller wavelength high-celerity gravel bars as the bed decreased in relief. To explore the transient response we modeled both cases with a 2-D depth

  17. Bed-material, channel stability, and regional gravel production dynamics in Oregon coastal rivers

    NASA Astrophysics Data System (ADS)

    Jones, K. L.; O'Connor, J. E.; Wallick, R.; Anderson, S.; Keith, M. K.; Mangano, J. F.

    2010-12-01

    Along the Oregon coast, gravel-bed rivers of various basin sizes and network topologies carve their way to the Pacific Ocean through a suite of geologic formations and land-use activities. To date, we have initiated assessments of bed-material condition and channel stability for seven coastal Oregon rivers (from north to south: Nehalem, Tillamook, Umpqua, Coquille, Rogue, Hunter, and Chetco). These river channels are of interest, in part, due to historic and on-going removal of gravels for commercial aggregate. Gravel extraction alone or in conjunction with the effects of other land uses may initiate a variety of channel changes, leading to channel instability. For each river, we synthesize multiple lines of evidence (including field observations, particle measurements, GIS analyses, specific gage analyses, and previous studies) to determine if the river channels are in equilibrium, degrading, or aggrading and if bed-material transport is likely limited by transport capacity or sediment supply. Initial field observations include the presence of reaches with some channel instability (mainly aggradation and channel widening) in the Hunter, Rogue, and Coquille basins. Our preliminary specific gage analyses indicate changes in the stage-discharge relationships at several gages, including a long-term gage on Rogue River near Grants Pass, where the channel has either incised or widened, resulting in a lowering of stage over time and different discharges. Building on our preliminary findings and review of the literature, we postulate that gravel production in coastal Oregon rivers is a function of the surrounding geology, basin slope, annual precipitation rates, channel bed elevation patterns (e.g., the length of the channel bed at sea level), and network structure. Bed-material supply tends to be greatest for rivers draining the Klamath terrane. Preliminary statistical analyses also show that the product of basin slope and mean annual precipitation describes 57% of the

  18. Effects of Gravel Bars on Nutrient Spiraling in Bedrock-Alluvium Streams

    NASA Astrophysics Data System (ADS)

    Iobst, B. R.; Carroll, E. P.; Furbish, D. J.

    2007-05-01

    The importance of the connection between nutrient transport and local stream geomorphology is becoming increasingly important. Studies have shown that the interconnectivity of nutrient cycles in the downstream direction is in part controlled by the distribution and size of gravel bars in low order streams, as hyporheic flow occurs dominantly through alternate and mid-channel gravel bars. For this investigation multiple gravel bars in a 3rd order bedrock-alluvium stream were studied to determine general relationships between nutrient spiraling and hyporheic flow. The first goal was to understand (1) the extent to which water moves through hyporheic zones and (2) the basic chemistry of the hyporheic water. The second part of the study was to understand how nutrients, notably nitrogen, are affected in their cycling by the relatively long residence times encountered in gravel bars during hyporheic flow. Wells were installed along a 600 m reach of Panther Creek, KY in selected bars, as well as in a secondary location involving a grid installation pattern in one large bar. Results have shown that hyporheic flow through gravel bars is an important factor in influencing stream chemistry. Background water chemistry surveys have shown that certain parameters, specifically ammonium and nitrogen concentrations vary downstream, and that the dominant control over these changes is gravel bar location. Rhodamine WT was used in field tracer tests to track the travel times of water through bars as well as partitioning of water between the open channel and hyporheic flows. Further tests will be conducted utilizing a stable isotope study to determine how nitrogen is affected by hyporheic flow, and what implications this has for nutrient transport. We expect results to show that the spacing and size of gravel bars is a dominant control in key nutrient spiraling parameters, namely uptake lengths and overall nitrogen cycling rates. This has implications for how natural systems will

  19. Runoff and Sediment Delivery from Bare and Graveled Forest Road Approaches to Stream Crossings

    NASA Astrophysics Data System (ADS)

    Brown, K. R.; McGuire, K. J.; Aust, W. M.

    2012-12-01

    Forested watersheds are typically associated with high quality water yield, yet forest roads and trails can adversely impact water quality draining forested watersheds. Increased stream sedimentation from forest road stream crossings often represents the most significant water quality threat associated with forestry operations. Quantification of sediment delivery rates is essential for the prescription of Best Management Practices (BMPs) that adequately address forest road stormwater runoff. Two different field experiments were implemented in the Virginia Piedmont to achieve the objectives of quantifying sediment delivery from forest roads where the road meets the stream (the road approach) and evaluating the sediment reduction efficacy of partially graveling road approaches. A forest operational experiment that included sediment traps and differential leveling was used to measure sediment delivery from five bare and four fully graveled road approaches for one year (August 2011 through July 2012). Rainfall simulation experiments were performed on six additional approaches to measure stormwater runoff volume, infiltration, and sediment delivery for 10 to 50-minute rain events with rainfall recurrence intervals of < 1 to 5-year return periods. Rainfall simulations were performed on newly-reopened bare approaches, with subsequent simulations on partially graveled approaches. The sediment trap study provides annual sediment delivery rates for bare and fully graveled road approaches. The rainfall simulation experiments characterize sediment delivery during storm events and provide an evaluation of different levels of Best Management Practice (BMP) implementation (i.e. ¼ to full gravel coverage) to minimize sediment inputs from road approaches. Sediment delivery from both experiments was related to rainfall amount, timing, and intensity, as well as road approach characteristics such as length, slope, and percentage of bare soil through stepwise multiple regression

  20. Ecological significance of riverine gravel bars in regulated river reaches below dams

    NASA Astrophysics Data System (ADS)

    Ock, G.; Takemon, Y.; Sumi, T.; Kondolf, G. M.

    2012-12-01

    A gravel bar has been recognized as ecologically significant in that they provide simplified habitat with topographical, hydrological and thermo-chemical diversity, while enhancing material exchanges as interfaces laterally between aquatic and terrestrial habitats, and vertically between surface and subsurface waters. During past several decades, regulated rivers below dams have been loss of a number of the geomorphological features due to sediment starvation by upstream dams, accompanied by a subsequent degradation of their ecological functions. Despite a growing concern for gravel bar management recognizing its importance in recovering riverine ecosystem services, the ecological roles of gravel bars have not been assessed enough from the empirical perspectives of habitat diversity and organic matter interactions. In this study, we investigate the 'natural filtering effects' for reducing lentic plankton and contaminants associated with self-purification, and 'physicochemical habitat complexity' of gravel bars, focusing on reach-scaled gravel bars in rivers located in three different countries; First is the Uji River in central Japan, where there has been a loss of gravel bars in the downstream reaches since an upstream dam was constructed in 1965; second is the Tagliamento River in northeast Italy, which shows morphologically intact braided bar channels by natural flooding events and sediment supply; third is the Trinity River in the United States (located in northern California), the site of ongoing restoration efforts for creating new gravel bars through gravel augmentation and channel rehabilitation activities. We traced the downstream changes in particulate organic matter (POM) trophic sources (composed of allochthonous terrestrial inputs, autochthonous instream production and lentic plankton from dam outflows) in order to evaluate the roles of the geomorphological features in tailwater ecosystem food-resources shifting. We calculated suspended POM

  1. Effects of gravel mulch on emergence of galleta grass seedlings. Oral summary report

    SciTech Connect

    Winkel, V.K.; Medrano, J.C.; Stanley, C.; Walo, M.D.

    1993-03-01

    The Department of Energy Nevada Operations Office, Technology Development and Program Management Division, has identified the need to clean up several sites on the Nevada Test Site and Tonopah Test Range contaminated with surface plutonium. An important objective of the project identified as the Plutonium In Soils Integrated Demonstration is to develop technologies to stabilize and restore the disturbed sites after decontamination. Revegetation of these contaminated sites will be difficult due to their location in the arid Mojave and Great Basin Deserts. The major factors which will affect successful plant establishment and growth at these sites are limited and sporadic precipitation, limited soil water, extreme air and soil temperatures, limited topsoil, and herbivory . Research has shown that providing microsites for seed via mulching can aid in plant emergence and establishment. Since many of the soils at the sites slated for plutonium decontamination have a large percentage of gravel in the upper 10 cm of soil, the use of gravel as mulch could provide microsites for seed and stabilize soils during subsequent revegetation of the sites. In July 1992, EG&G/EM Environmental Sciences Department initiated a greenhouse study to examine the possible benefits of gravel mulch. The specific objectives of this greenhouse study were to: (1) determine the effects seedling emergence and soil water, and (2) determine effects of irrigation rates on seedling emergence for gravel mulches and other conventional seedbed preparation techniques. A secondary objective was to determine the depth of gravel mulch that was optimal for seedling emergence. Results from this greenhouse study will assist in formulating specific reclamation plans for sites chosen for cleanup.

  2. Nearshore shore-oblique bars, gravel outcrops, and their correlation to shoreline change

    USGS Publications Warehouse

    Schupp, C.A.; McNinch, J.E.; List, J.H.

    2006-01-01

    This study demonstrates the physical concurrence of shore-oblique bars and gravel outcrops in the surf zone along the northern Outer Banks of North Carolina. These subaqueous features are spatially correlated with shoreline change at a range of temporal and spatial scales. Previous studies have noted the existence of beach-surf zone interactions, but in general, relationships between nearshore geological features and coastal change are poorly understood. These new findings should be considered when exploring coastal zone dynamics and developing predictive engineering models. The surf zone and nearshore region of the Outer Banks is predominantly planar and sandy, but there are several discrete regions with shore-oblique bars and interspersed gravel outcrops. These bar fields have relief up to 3??m, are several kilometers wide, and were relatively stationary over a 1.5??year survey period; however, the shoreward component of the bar field does exhibit change during this time frame. All gravel outcrops observed in the study region, a 40??km longshore length, were located adjacent to a shore-oblique bar, in a trough that had width and length similar to that of the associated bar. Seismic surveys show that the outcrops are part of a gravel stratum underlying the active surface sand layer. Cross-correlation analyses demonstrate high correlation of monthly and multi-decadal shoreline change rates with the adjacent surf-zone bathymetry and sediment distribution. Regionally, areas with shore-oblique bars and gravel outcrops are correlated with on-shore areas of high short-term shoreline variability and high long-term shoreline change rates. The major peaks in long-term shoreline erosion are onshore of shore-oblique bars, but not all areas with high rates of long-term shoreline change are associated with shore-oblique bars and troughs. ?? 2006 Elsevier B.V. All rights reserved.

  3. Run-of-River Impoundments Can Remain Unfilled While Transporting Gravel Bedload: Numerical Modeling Results

    NASA Astrophysics Data System (ADS)

    Pearson, A.; Pizzuto, J. E.

    2015-12-01

    Previous work at run-of-river (ROR) dams in northern Delaware has shown that bedload supplied to ROR impoundments can be transported over the dam when impoundments remain unfilled. Transport is facilitated by high levels of sand in the impoundment that lowers the critical shear stresses for particle entrainment, and an inversely sloping sediment ramp connecting the impoundment bed (where the water depth is typically equal to the dam height) with the top of the dam (Pearson and Pizzuto, in press). We demonstrate with one-dimensional bed material transport modeling that bed material can move through impoundments and that equilibrium transport (i.e., a balance between supply to and export from the impoundment, with a constant bed elevation) is possible even when the bed elevation is below the top of the dam. Based on our field work and previous HEC-RAS modeling, we assess bed material transport capacity at the base of the sediment ramp (and ignore detailed processes carrying sediment up and ramp and over the dam). The hydraulics at the base of the ramp are computed using a weir equation, providing estimates of water depth, velocity, and friction, based on the discharge and sediment grain size distribution of the impoundment. Bedload transport rates are computed using the Wilcock-Crowe equation, and changes in the impoundment's bed elevation are determined by sediment continuity. Our results indicate that impoundments pass the gravel supplied from upstream with deep pools when gravel supply rate is low, gravel grain sizes are relatively small, sand supply is high, and discharge is high. Conversely, impoundments will tend to fill their pools when gravel supply rate is high, gravel grain sizes are relatively large, sand supply is low, and discharge is low. The rate of bedload supplied to an impoundment is the primary control on how fast equilibrium transport is reached, with discharge having almost no influence on the timing of equilibrium.

  4. Outer region scaling using the freestream velocity for nonuniform open channel flow over gravel

    NASA Astrophysics Data System (ADS)

    Stewart, Robert L.; Fox, James F.

    2017-06-01

    The theoretical basis for outer region scaling using the freestream velocity for nonuniform open channel flows over gravel is derived and tested for the first time. Owing to the gradual expansion of the flow within the nonuniform case presented, it is hypothesized that the flow can be defined as an equilibrium turbulent boundary layer using the asymptotic invariance principle. The hypothesis is supported using similarity analysis to derive a solution, followed by further testing with experimental datasets. For the latter, 38 newly collected experimental velocity profiles across three nonuniform flows over gravel in a hydraulic flume are tested as are 43 velocity profiles previously published in seven peer-reviewed journal papers that focused on fluid mechanics of nonuniform open channel over gravel. The findings support the nonuniform flows as equilibrium defined by the asymptotic invariance principle, which is reflective of the consistency of the turbulent structure's form and function within the expanding flow. However, roughness impacts the flow structure when comparing across the published experimental datasets. As a secondary objective, we show how previously published mixed scales can be used to assist with freestream velocity scaling of the velocity deficit and thus empirically account for the roughness effects that extend into the outer region of the flow. One broader finding of this study is providing the theoretical context to relax the use of the elusive friction velocity when scaling nonuniform flows in gravel bed rivers; and instead to apply the freestream velocity. A second broader finding highlighted by our results is that scaling of nonuniform flow in gravel bed rivers is still not fully resolved theoretically since mixed scaling relies to some degree on empiricism. As researchers resolve the form and function of macroturbulence in the outer region, we hope to see the closing of this research gap.

  5. The influence of three methods of gravel cleaning on brown trout, Salmo trutta, egg survival

    NASA Astrophysics Data System (ADS)

    Shackle, Victoria J.; Hughes, Simon; Lewis, Vaughan T.

    1999-02-01

    Siltation of spawning gravels in upland rivers appears to be an increasing hindrance to salmonids' spawning success. River managers seek an effective and non-labour intensive means of loosening gravel and reducing fine material, so improving spawning success; this study compared three practical gravel cleaning techniques, applied at realistic (rather than intensive) levels, by assessing survival to hatching of buried brown trout, Salmo trutta L., ova at five sites on four rivers with gravel substrate in southern England. Each site consisted of six reaches, of which three were cleaned by tractor rotovating, high pressure jet washing and pump washing; these were compared with adjacent, untreated reaches. Brown trout ova were buried in both fine mesh and coarse mesh boxes in each reach.Significant improvements (at P<0·05) in survival (number of live alevins) were found in three of the five pump washed reaches, two of the five tractor rotovated reaches and one pressure washed reach when the data were analysed by site. When data from all five sites were analysed together, all treated reaches showed a significant improvement (at P<0·05) in egg survival to hatching compared with control reaches for fine mesh egg boxes; for coarse mesh boxes only pump washed reaches showed such an improvement.We feel that pump-washing provides the most effective, inexpensive and suitably non labour-intensive means of improving gravel, although ultimately it may be better to reduce the silt load of rivers. Freeze core bed samples taken before and immediately after cleaning were analysed for silt content; pump washing and high pressure washing may have reduced the amount of fine material.

  6. Paleocurrent and fabric analyses of the imbricated fluvial gravel deposits in Huangshui Valley, the northeastern Tibetan Plateau, China

    USGS Publications Warehouse

    Miao, X.; Lu, H.; Li, Z.; Cao, G.

    2008-01-01

    Gravel deposits on fluvial terraces contain a wealth of information about the paleofluvial system. In this study, flow direction and provenance were determined by systematic counts of more than 2000 clasts of imbricated gravel deposits in the Xining Region, northeastern Tibetan Plateau, China. These gravel deposits range in age from the modern Huangshui riverbed to Miocene-aged deposits overlain by eolian sediments. Our major objectives were not only to collect first-hand field data on the fluvial gravel sediments of the Xining Region, but also to the reconstruct the evolution of the fluvial system. These data may offer valuable information about uplift of the northeastern Tibetan Plateau during the late Cenozoic era. Reconstructed flow directions of the higher and lower gravel deposits imply that the river underwent a flow reversal of approximately 130-180??. In addition, the lithological compositions in the higher gravel deposits differ significantly from the lower terraces, suggesting that the source areas changed at the same time. Eolian stratigraphy overlying the gravel deposits and paleomagnetic age determination indicate that this change occurred sometime between 1.55??Ma and 1.2??Ma. We suggest that tectonic activity could explain the dramatic changes in flow direction and lithological composition during this time period. Therefore, this study provides a new scenario of fluvial response to tectonic uplift: a reversal of flow direction. In addition, field observation and statistical analyses reveal a strong relationship between rock type, size and roundness of clasts. ?? 2007 Elsevier B.V. All rights reserved.

  7. Pliocene Cosmogenic Nuclide Burial Ages of the Nenana Gravel: Progress in Dating and Implications for Alaska Range Evolution

    NASA Astrophysics Data System (ADS)

    Goehring, B. M.; Bemis, S. P.; Ward, D.; Caffee, M. W.; Sortor, R. N.

    2015-12-01

    The Nenana Gravel is an up to 1.2 km thick foreland basin deposit that spans the north flank of the Alaska Range. It is uplifted relative to the active foreland basin to the north. It is also deformed to various degree dependent on its location within the northern Alaska Range thrust system. Because this foreland basin sequence records the unroofing and northward propagation of the Alaska Range, direct dating of the Nenana Gravel, especially over wide spatial distribution along the Alaska Range, will substantially advance our understanding of the style and timing of deformation of the Alaska Range. At present though, age estimates for the Nenana Gravel are limited to a single maximum limiting age and uncertain minimum limiting age with no little or no insight as to the spatial variation in Nenana Gravel deposition timing. We present the first direct dates of deposition ages of the Nenana Gravel using cosmogenic nuclide burial dating. Results indicate that deposition of the Nenana Gravel began ca. 6.5 Ma, in stratigraphic agreement with a maximum limiting tephra age from the underlying Usibelli Group. Additional samples from the Nenana Gravel basal contact and higher in the section are presently underway. The resultant burial ages are amongst the oldest 26Al-10Be burial ages ever produced and highlight the potential of the method to directly date sediments in the Pliocene, particularly given recent advancements in the accelerator mass spectrometry measurement of 26Al/27Al isotope ratios.

  8. Gravel bars can be critical for biodiversity conservation: a case study on scaly-sided Merganser in South china.

    PubMed

    Zeng, Qing; Shi, Linlu; Wen, Li; Chen, Junzhu; Duo, Hairui; Lei, Guangchun

    2015-01-01

    Gravel bars are characteristic components of river landscapes and are increasingly recognized as key sites for many waterbirds, though detailed studies on the ecological function of gravel bars for waterbirds are rare. In this study, we surveyed the endangered Scaly-sided Merganser Mergus squamatus along a 40 km river section of Yuan River, in Central China, for three consecutive winters. We derived the landscape metrics of river gravel bars from geo-rectified fine resolution (0.6 m) aerial image data. We then built habitat suitability models (Generalized Linear Models-GLMs) to study the effects of landscape metrics and human disturbance on Scaly-sided Merganser presence probability. We found that 1) the Scaly-sided Merganser tended to congregate at river segments with more gravel patches; 2) the Scaly-sided Merganser preferred areas with larger and more contiguous gravel patches; and 3) the number of houses along the river bank (a proxy for anthropogenic disturbance) had significantly negative impacts on the occurrence of the Scaly-sided Merganser. Our results suggest that gravel bars are vital to the Scaly-sided Merganser as shelters from disturbance, as well as sites for feeding and roosting. Therefore, maintaining the exposure of gravel bars in regulated rivers during the low water period in winter might be the key for the conservation of the endangered species. These findings have important implications for understanding behavioral evolution and distribution of the species and for delineating between habitats of different quality for conservation and management.

  9. [Runoff and sediment yielding processes on red soil engineering accumulation containing gravels by a simulated rainfall experiment].

    PubMed

    Shi, Qian-hua; Wang, Wen-long; Guo, Ming-ming; Bai, Yun; Deng, Li-qiang; Li, Jian-ming; Li, Yao-lin

    2015-09-01

    Engineering accumulation formed in production and construction projects is characterized by unique structure and complex material composition. Characteristics of soil erosion on the engineering accumulation significantly differ from those on farmland. An artificially simulated rainfall experiment was carried out to investigate the effects of rainfall intensity on the processes of runoff and sediment yielding on the engineering accumulation of different gravel contents (0%, 10%, 20% and 30%) in red soil regions. Results showed that the initial time of runoff generation decreased with increases in rainfall intensity and gravel content, the decreased amplitudes being about 48.5%-77.9% and 4.2%-34.2%, respectively. The initial time was found to be a power function of rainfall intensity. Both runoff velocity and runoff rate manifested a trend of first rising and then in a steady state with runoff duration. Rainfall intensity was found to be the main factor influencing runoff velocity and runoff rate, whereas the influence of gravel content was not significant. About 10% of gravel content was determined to be a critical value in the influence of gravel content on runoff volume. For the underlying surface of 10% gravel content, the runoff volume was least at rainfall intensity of 1.0 mm · min(-1) and maximum at rainfall intensity of greater than 1.0 mm · min(-1). The runoff volume in- creased 10%-60% with increase in rainfall intensity. Sediment concentration showed a sharp decline in first 6 min and then in a stable state in rest of time. Influence of rainfall intensity on sediment concentration decreased as gravel content increased. Gravels could reduce sediment yield significantly at rainfall intensity of greater than 1.0 mm · min(-1). Sediment yield was found to be a linear function of rainfall intensity and gravel content.

  10. Effects of gravel on infiltration, runoff, and sediment yield in landslide deposit slope in Wenchuan earthquake area, China.

    PubMed

    Li, Tianyang; He, Binghui; Chen, Zhanpeng; Zhang, Yi; Liang, Chuan; Wang, Renxin

    2016-06-01

    Amounts of landslide deposits were triggered by the Wenchuan earthquake with magnitude 8.0 on May 12, 2008. The landslide deposits were composed of soil and rock fragments, which play important roles in hydrological and erosion processes in the steep slope of landslide deposits. The mixtures of soil and gravels are common in the top layers of landslide deposits, and its processes are obviously different with the soil without gravels. Based on the data of field investigation, a series of simulated scouring flow experiments with four proportion of gravel (0, 25, 33.3, and 50 %) and three scouring flow rates (4, 8, 12 L/min) under two steep slopes (67.5, 72.7 %) were conducted sequentially to know the effects of proportion of gravel on infiltration capacity, runoff generation, and sediment production in the steep slope of landslide deposit. Results indicated that gravel had promoted or reduced effects on infiltration capacity which could affect further the cumulative runoff volume and cumulative sediment mass increase or decrease. The cumulative infiltration volume in 25 % proportion of gravel was less than those in 0, 33.3, and 50 % proportion of gravel. The cumulative runoff volume was in an order of 25 > 0 > 33.3 > 50 % while cumulative sediment mass ranked as 25 > 33.3 > 0 > 50 % with different proportions of gravel. A significant power relationship was found between scouring time and cumulative runoff volume as well as cumulative sediment mass. The relationship between average soil and water loss rate and proportion of gravel was able to express by quadratic function, with a high degree of reliability. The results have important implications for soil and water conservation and modeling in landslide deposit but also provide useful information for the similar conditions.

  11. Different bed surface and flow resistance characteristics for gravel and sand bed

    NASA Astrophysics Data System (ADS)

    Fan, N.; Yang, K.; Nie, R.; Liu, X.

    2014-12-01

    Bed forms affect both bed load transport and flow resistance strongly and change their shapes and sizes depending on underlying grain size distribution and shear stress. A series of flume experiments were conducted at the Saint Anthony Falls Laboratory to study the effect of bed form dynamics on flow turbulence and sediment transport with both gravel and sand as bed material and different flow conditions. From the experimental data, the spectrum of bed elevation time series, the PDFs of bed elevation increments and the flow resistance characteristics are all analyzed. The wavelet-based spectral analysis shows that the slopes of the elevation spectrums are -2 and -3 for gravel and sand bed surfaces, respectively. The slope -3 indicates that the surface is self-similar, in another words, the ratios of bed form heights and lengths for different bed forms are the same; however, the slope of -2 indicates that the surface is self-affine, and in such case (-2) the ratios of bed form heights and lengths for different bed forms are not correlated at all. We interpret that the relative size of grain and boundary layer affects the bed form characteristics significantly, e.g., grain size of sand is of the same scale as the thickness of boundary layer, but both are much smaller than the grain size of gravel. Our results suggest that the PDFs of bed elevation increments for both gravel and sand beds can be fitted well with two-sided asymmetric exponential function. Furthermore, we show that the flow resistance (Darcy-Weisbach coefficients f) are much higher for sand bed than gravel bed, and the former is contributed by form drags, which is much larger than grain drags. For gravel bed, f and the skewness of bed elevation increments increases with flow discharge whereas for the sand bed, both f and the skewness of bed elevation increments decreases which corresponds to the transition in hydraulic conditions for dune to dynamic flat surface in our experiments. The analysis

  12. The Effect of Fines in Mixed Size Sediment Transport in a Gravel Bed

    NASA Astrophysics Data System (ADS)

    Hill, K. M.; Baumgardner, S.; Gaffney, J.; Wilcock, P.; Paola, C.

    2011-12-01

    Washload is a widely recognized concept that remains difficult to define. In a gravel-bed river, washload has been defined as those sizes present in the bed only in small proportions. It has also been defined as the portion of transported sediment that has little effect on bed material transport. We experimentally investigate the impact of fine sediment on the mobility and composition of a gravel bed. We conducted flume experiments using a constant water discharge and feed rate of gravel. After reaching steady state, we doubled the feed rate by feeding sediment of finer size, using size ratios from 1:1 to 1:16. As we decrease the size of the fine particles relative to the size of the gravel particles, the system transitions between three regimes. (1) For particle size ratios close to one, the bed slope increases to supply the additional shear stress needed to transport the additional load of similar-sized particles. (2) For intermediate particle size ratios the increased fines content increases the mobility of the sediment mix, resulting in a decreased bed slope. The bed composition is a mix of fine and coarse grains. (3) For the largest particle size ratios (the smallest fines), the additional fines travel primarily in suspension and cause essentially no change in bed slope, though the subsurface becomes clogged with fine sediment. The behavior for near-unity and intermediate particle size ratios can be predicted using a mixed-size bed-material transport formula. For the mixtures with the smallest fine particles, the presence of fines has little effect on the mobility of the gravel and thus the total transport can no longer be predicted with a bed material transport formula. These results provide useful insights concerning the nature of wash load. The effect of sediment feed on gravel mobility and bed slope is not controlled solely by the amount of fines in the bed (the first definition of wash load), but also depends strongly on the relative grain size of the

  13. Experiments on seismic behavior of back-fill gravel layer as liquefaction countermeasure of buried gas pipelines

    SciTech Connect

    Takada, Shiro; Ogawa, Yasuo; Shimizu, Kenji; Ueno, Junichi

    1995-12-31

    Experiments on seismic behavior of back-fill gravel layer as a back-fill material for buried pipelines was experimented with to investigate the effectiveness against liquefaction with a scaled model using a shaking table. A non-liquefied sandy surface layer was made with a steel mold divided into several pieces for a model. The back-fill gravel was found to be efficient for drainage but didn`t prevent liquefaction from occurring in the below layer. It was also found that the pipe doesn`t move up by buoyancy but subsides following the settlement of the back-fill gravel.

  14. Using passive, thermal remote sensing techniques for detecting subsurface gravel accumulations in vegetated, unconsolidated sedimentary terrains

    NASA Technical Reports Server (NTRS)

    Burns, Gregory S.; Scholen, Douglas E.

    1989-01-01

    Multiband radiometric data from an airborne imaging thermal scanner are being studied for use in finding buried gravel deposits. The techniques are based on measuring relative differences in the thermal properties between gravel-laden targets and the surrounding gravelless background. These properties are determined from modeling the spectral radiant emittance recorded over both types of surfaces in conjunction with ground measurements of the most significant heat flows above and below the surface. Thermodynamic properties of sampled materials from control sites are determined, and diurnal and annual subsurface heat waves are recorded. Thermal models that account for heat exchange at the surface, as well as varying levels of soil moisture, humidity, and vegetation, are needed for adaptation and modification to simulate the physical and radiative environments of this region.

  15. Crumb rubber impact to the mechanical performance of concrete based at round gravel

    NASA Astrophysics Data System (ADS)

    Bouaka, Wafa; Kriker, Abdelouahed

    2017-02-01

    Today the concrete is used more than any other construction material, with almost four (4) billion cubic meters used worldwide [1]. Throughout history, mankind has used concrete in construction. Concrete has not only been used in the construction of buildings such as dwelling areas but also in bridges, roads, tunnels, airports and water dams. It is a heterogeneous composite resulting from cement, aggregates, water and a limited quantity of adjuvant. The round gravel is an existing traditional material within the formulation of concrete. It is high in resistance to fragmentation and widely spread out in grand quantity in the Saharian regions. However, its utilization remains rare in different types of construction. The purpose of this study is to compare and contrast the use of local materials (Round gravel) with polymer industrial products (Crumb Rubber). This one is used to enhance the density, homogeneity, malleability and strength of the construction material.

  16. Penetration and survival of riparian tree roots in compacted coarse gravel mixtures

    NASA Astrophysics Data System (ADS)

    Muellner, Michael; Weissteiner, Clemens; Konzel, Christoph; Rauch, Hans Peter

    2016-04-01

    Root growth and penetration of riparian trees along paved cycling paths and service roads of rivers causes often traffic safety problems. Damages occur mostly on street surfaces with thin asphalt layers and especially in the upper part of the pavement structure. The maintainers of these roads are faced with frequent and high annual repair costs in order to guarantee traffic safety and pleasant cycling conditions. Analyses of the dominating process mechanisms demonstrated that mainly the naturally growing pioneer vegetation along rivers is responsible for the asphalt damages caused by their constant and rapid growth. The investigations of the root growth characteristics showed that tree roots mostly penetrate the road structure between the gravel sublayer and the asphalt because of the high compaction of the layer itself. In a second step of the research project the influence of different gravel size mixtures on the root penetration and survival are analysed. Coarse gravel size mixtures with the lowest possible fine granular fraction are suposed to inhibit root growth due to the mechanical impedance and air pruning of roots. Furthermore coarse gravel size mixtures could influence the presence of condensate formed at the underside of the asphalt layer. Therefore seven different compositions of matrix stone gravel size mixtures (0/32, 4/32, 8/32, 16/32, 0/64, 8/64 hydraulic bound mixture and 16/64) as sublayer material were tested in a small scale experimental set-up. Wooden boxes with a dimension of 1x1.5x0.5 m and 0.5x0.5x0.5 m were used as frames for the different matrix stone mixtures. On one side the boxes were delimited to the surrounding soil with a steel mesh followed by a wire mesh and a geotextile. Boxes were located in an 80 cm deep hole on a 30 cm thick drainage layer. Willow and poplar cuttings were planted laterally to the root penetrable side of the boxes. Large boxes were filled and compacted with 6 different gravel size mixtures (all but 4/32) and

  17. Kali Gandaki gravel deposits of central West Nepal — their neotectonic significance

    NASA Astrophysics Data System (ADS)

    Sharma, Toran; Upreti, B. N.; Vashi, N. M.

    1980-02-01

    The terraced gravel deposits of the Baglung-Behadi region in the Kali Gandaki valley, central West Nepal, reveal geomorphic features related to neotectonism. The accumulation of thick fluvioglacial gravel deposits in lake-like basins along the then existing river course took place due to the uplift of the southern Mahabharat Range and the relative subsidence of the Midland. The deposits consist of unsorted fragments of variable size, showing considerable uniformity laterally over large areas from north to south, and with abundant angular to sub-rounded boulders of Dhaulagiri limestone and gneisses of the Main Central Crystallines. Terrace flats arranged in three successive levels on either side of Kali Gandaki show that the region has undergone at least three periods of uplift.

  18. Improving the behavior of body roads by the use of gravel-slag mixture

    NASA Astrophysics Data System (ADS)

    Hadinane, Hocine; Oucief, Hocine; Merzoud, Mouloud

    2016-07-01

    The accumulation of wastes industrial stemming of the iron and steel industry has influenced negatively the environment. The adopted policy had for mission to eliminate these undesirable wastes by recycling them by their utilization in adequate areas. The objective of this work is to study the mechanical behavior of a gravel-slag based on crystallized and granulated slag, activated by lime. One will be interested in the study of resistance to punching and the bearing ratio of this slag through Proctor tests, CBR and by compression, tensile tests, for use in the layers of pavement (Foundation and base layers). The obtained result on gravel-slag show considerable performances, compared with natural aggregates point of resistance and thickness of the layers. Its utilization in the road area has allowed therefore the recycling these industrial wastes, to decrease the pollution, to use a minimum noble product requiring important exploitation energy and an economy on layers of surface realized with costly materials (bituminous concrete).

  19. Sediment transport and siltation of brown trout (Salmo trutta L.) spawning gravels in chalk streams

    NASA Astrophysics Data System (ADS)

    Acornley, R. M.; Sear, D. A.

    1999-02-01

    Deposition rates of fine sediment into brown trout spawning gravels were measured at monthly intervals for a period of one year in a small channel of the River Test, Hampshire. Data were also collected on stream discharge, water depth, flow velocity and suspended sediment concentrations. Deposition rates followed a seasonal pattern and were maximal during periods of high discharge in the late winter/early spring when suspended sediment concentrations were high. The material deposited in the spawning gravels included silts and fine sands (<250 m) that were transported in suspension and coarser fragments of low density tufa-like material that were transported as bed load. The ecological implications of fine sediment deposition for salmonid egg survival in chalk streams are considered.

  20. Unfolding the fast neutron spectra of a BC501A liquid scintillation detector using GRAVEL method

    NASA Astrophysics Data System (ADS)

    Chen, YongHao; Chen, XiMeng; Lei, JiaRong; An, Li; Zhang, XiaoDong; Shao, JianXiong; Zheng, Pu; Wang, XinHua

    2014-10-01

    Accurate knowledge of the neutron energy spectra is useful in basic research and applications. The overall procedure of measuring and unfolding the fast neutron energy spectra with BC501A liquid scintillation detector is described. The recoil proton spectrum of 241Am-Be neutrons was obtained experimentally. With the NRESP7 code, the response matrix of detector was simulated. Combining the recoil proton spectrum and response matrix, the unfolding of neutron spectra was performed by GRAVEL iterative algorithm. A MatLab program based on the GRAVEL method was developed. The continuous neutron spectrum of 241Am-Be source and monoenergetic neutron spectrum of D-T source have been unfolded successfully and are in good agreement with their standard reference spectra. The unfolded 241Am-Be spectrum are more accurate than the spectra unfolded by artificial neural networks in recent years.

  1. Vegetation control of gravel-bed channel morphology and adjustment: the case of Carex nudata

    NASA Astrophysics Data System (ADS)

    McDowell, P. F.

    2010-12-01

    In the high energy, gravel- to cobble-bed Middle Fork John Day River of eastern Oregon, C. nudata (torrent sedge) germinates on gravel bars and forms tussocks 0.5 m across by 0.3m high or larger, with dense, tough root masses that are very resistant to erosion. Tussocks may be uprooted during floods (probably >Q-5yr), travel as boulder-sized masses, and may re-root where deposited. Individual tussocks, however, commonly persist for more than a decade in one position. When established, these tussocks behave more like channel obstructions than typical stream side sedges. Lines of C. nudata tussocks form on the stream side margin of former bare gravel bars, creating a secondary flow path and an eroding bank on their landward side. C. nudata also forms small mid-channel islets with bed scour at their base and occasional lee depositional zones. Chains of mid-channel islets can anchor pool boundaries. Observations in the field and from aerial photo time sequences suggest the following evolutionary model for channels with C. nudata. C. nudata establishes on a bare gravel bar, and can stabilize the bar surface or create erosional forms as described above. C. nudata fosters weaker sedges and other species that help extend stabilization of the bar surface. Mid-channel islets form through selective uprooting of tussocks. Observations of a reach where cattle grazing was eliminated in 2000 show that C. nudata has expanded. It has stabilized some formerly active bar surfaces but is now causing bank erosion and channel widening in some locations. In this case, C. nudata mediated the potentially stabilizing effects of management change by increasing channel instability in some respects.

  2. Rehabilitating gravel areas with short-hair sedge sod plugs and fertilizer

    Treesearch

    Raymond D. Ratliff

    1985-01-01

    Tests to rehabilitate gravel areas in high value recreation sites were carried out by transplanting short-hair sedge (Carex exserta) plugs. The plugs were 1.9 cm (0.75 inch) and 5.1 cm (2.0 inches) in diameter, 10 cm (4.0 inches) deep, and were transplanted in September 1981, with and without papier-mache pots. The test site was Siberian Outpost, in...

  3. Identification of hydraulic conductivity structure in sand and gravel aquifers: Cape Cod data set

    USGS Publications Warehouse

    Eggleston, J.R.; Rojstaczer, S.A.; Peirce, J.J.

    1996-01-01

    This study evaluates commonly used geostatistical methods to assess reproduction of hydraulic conductivity (K) structure and sensitivity under limiting amounts of data. Extensive conductivity measurements from the Cape Cod sand and gravel aquifer are used to evaluate two geostatistical estimation methods, conditional mean as an estimate and ordinary kriging, and two stochastic simulation methods, simulated annealing and sequential Gaussian simulation. Our results indicate that for relatively homogeneousand and gravel aquifers such as the Cape Cod aquifer, neither estimation methods nor stochastic simulation methods give highly accurate point predictions of hydraulic conductivity despite the high density of collected data. Although the stochastic simulation methods yielded higher errors than the estimation methods, the stochastic simulation methods yielded better reproduction of the measured In (K) distribution and better reproduction of local contrasts in In (K). The inability of kriging to reproduce high In (K) values, as reaffirmed by this study, provides a strong instigation for choosing stochastic simulation methods to generate conductivity fields when performing fine-scale contaminant transport modeling. Results also indicate that estimation error is relatively insensitive to the number of hydraulic conductivity measurementso long as more than a threshold number of data are used to condition the realizations. This threshold occurs for the Cape Cod site when there are approximately three conductivity measurements per integral volume. The lack of improvement with additional data suggests that although fine-scale hydraulic conductivity structure is evident in the variogram, it is not accurately reproduced by geostatistical estimation methods. If the Cape Cod aquifer spatial conductivity characteristics are indicative of other sand and gravel deposits, then the results on predictive error versus data collection obtained here have significant practical consequences

  4. Sabah Shell Petroleum Company's (SSPC) experience in gravel-packing long perforated intervals in deviated holes

    SciTech Connect

    van Ballegooyen, J.; Seng, T.K.; Giap, T.K.

    1982-01-01

    This work presents the experience gained by Sabah Shell Petroleum Co. in gravel packing long, high angle intervals in a multilayered sand/shale sequence in the South Furious Field offshore N. Sabah, Malaysia. The selection of mechanical equipment, fluid properties, and a suitable tool for logging the quality of the pack are discussed. The placement procedure was modified, mostly by trial and error, until an acceptable technique was achieved. The evolution of this technique is discussed.

  5. Barrier erosion control test plan: Gravel mulch, vegetation, and soil water interactions

    SciTech Connect

    Waugh, W.J.; Link, S.O. )

    1988-07-01

    Soil erosion could reduce the water storage capacity of barriers that have been proposed for the disposal of near-surface waste at the US Department of Energy's Hanford Site. Gravel mixed into the top soil surface may create a self-healing veneer that greatly retards soil loss. However, gravel admixtures may also enhance infiltration of rainwater, suppress plant growth and water extraction, and lead to the leaching of underlying waste. This report describes plans for two experiments that were designed to test hypotheses concerning the interactive effects of surface gravel admixtures, revegetation, and enhanced precipitation on soil water balance and plant abundance. The first experiment is a factorial field plot set up on the site selected as a soil borrow area for the eventual construction of barriers. The treatments, arranged in a a split-split-plot design structure, include two densities of gravel admix, a mixture of native and introduced grasses, and irrigation to simulate a wetter climate. Changes in soil water storage and plant cover are monitored with neutron moisture probes and point intercept sampling, respectively. The second experiment consists of an array of 80 lysimeters containing several different barrier prototypes. Surface treatments are similar to the field-plot experiment. Drainage is collected from a valve at the base of each lysimeter tube, and evapotranspiration is estimated by subtraction. The lysimeters are also designed to be coupled to a whole-plant gas exchange system that will be used to conduct controlled experiments on evapotranspiration for modeling purposes. 56 refs., 6 figs., 8 tabs.

  6. Experimental evidence for the effect of hydrographs on sediment pulse dynamics in gravel-bedded rivers

    NASA Astrophysics Data System (ADS)

    Humphries, Robert; Venditti, Jeremy G.; Sklar, Leonard S.; Wooster, John K.

    2012-01-01

    Gravel augmentation is a river restoration technique applied to channels downstream of dams where size-selective transport and lack of gravel resupply have created armored, relatively immobile channel beds. Augmentation sediment pulses rely on flow releases to move the material downstream and create conditions conducive to salmon spawning and rearing. Yet how sediment pulses respond to flow releases is often unknown. Here we explore how three types of dam releases (constant flow, small hydrograph, and large hydrograph) impact sediment transport and pulse behavior (translation and dispersion) in a channel with forced bar-pool morphology. We use the term sediment "pulse" generically to refer to the sediment introduced to the channel, the zone of pronounced bed material transport that it causes, and the sediment wave that may form in the channel from the additional sediment supply, which can include input sediment and bed material. In our experiments, we held the volume of water released constant, which is equivalent to holding the cost of purchasing a water volume constant in a stream restoration project. The sediment pulses had the same grain size as the bed material in the channel. We found that a constant flow 60% greater than the discharge required to initiate sediment motion caused a mixture of translation and dispersion of the sediment pulse. A broad crested hydrograph with a peak flow 2.5 times the discharge required for entrainment caused pulse dispersion, while a more peaked hydrograph >3 times the entrainment threshold discharge caused pulse dispersion with some translation. The hydrographs produced a well-defined clockwise hysteresis effecting sediment transport, as is often observed for fine-sediment transport and transport-limited gravel bed rivers. The results imply a rational basis for design of water releases associated with gravel augmentation that is directly linked to the desired sediment behavior.

  7. An equation for bed-load transport capacities in gravel-bed rivers

    NASA Astrophysics Data System (ADS)

    Gao, Peng

    2011-05-01

    SummaryDetailed hydraulic and sedimentary information is needed to accurately predict bed-load transport rates in natural gravel-bed rivers. Yet, being able to estimate maximum transport rates from simple measurements would greatly benefit various sediment-related river management practices. To this end, a new concept of bed-load transport capacity for heterogeneous grains in gravel-bed rivers was introduced as the maximum possible transport rate a gravel-bed river can have for a given value of dimensionless shear stress, calculated using the median size of bed-load grains. Flows that can transport bed load at capacity may be identified by the criterion that the median size of bed-load grains must be greater than or equal to that of the bed substrate. Then, a single coefficient, power equation was developed to predict such capacities using bed-load capacity data covering both low flows with an armor layer and high flows without it. The good performance of this empirical equation was confirmed by comparing its predictability with that of Mayer Peter and Muller's and Bagnold's bed-load equations. Using an independent data compiled from six gravel-bed rivers in Idaho, not only was the empirical equation validated but also the criterion for identifying the condition under which bed load is transported at capacity was tested. In practice, the empirical equation can be used to estimate the maximum possible bed-load transport rates during high flow events, which is useful for various sediment-related river managements.

  8. A Literature Review of Processes for Gravel Deposit Identification in the Lower Mississippi River

    DTIC Science & Technology

    2010-07-01

    25 Figure 18. Interpretation of GPR data collected near an active sand and gravel quarry (Lucius et al...resistivity, ground penetrat- ing radar ( GPR ), time domain electromagnetism (TDEM), and frequency domain electromagnetism (FDEM). A brief summary of...exploration. GPR is an electromagnetic method that depends on the propagation of high-frequency (10-MHz to 3-GHz) electro- magnetic energy in the ground

  9. 133. ARAII SL1 burial ground. Shows gravel path from ARAII ...

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

    133. ARA-II SL-1 burial ground. Shows gravel path from ARA-II compound to the burial ground, detail of security fence and entry gate, and sign "Danger radiation hazard." F. C. Torkelson Company 842-area-101-1. Date: October 1961. Ineel index code no. 059-0101-00-851-150723. - Idaho National Engineering Laboratory, Army Reactors Experimental Area, Scoville, Butte County, ID

  10. Stentless pediatric ureteroscopic holmium: YAG laser stone disintegration: is gravels retrieval an issue?

    PubMed

    Gamal, W; Aldahshoury, M; Hammady, A; Hussein, Mohamed; Osman, M; Mmdouh, Ahmed; Abouzeid, A

    2011-09-01

    To evaluate the safety and efficacy of stentless pediatric ureteroscopic holmium laser stone disintegration without gravels retrieval. From Feb 2007 to Feb 2010, 21 children (12 boys and 9 girls) with unilateral single stone ureter, with an average age of 8.5 years (range 4-12 years), were treated with 6.9 Fr semirigid ureteroscope for a stone size ranged from 5 to 10 mm (mean 6.5 mm). All the stones were radioopaque, located in the upper ureter in 2 cases (9.5%), in the middle ureter in 5 cases (24%), and in the lower ureter in 14 cases (66.5%). Complete holmium laser stone disintegration was applied in all cases without gravels removal. No postoperative ureteral stent was inserted in any case. The stones were successfully approached and completely disintegrated in a single session in 20 cases (95.2%). All the procedures were done without ureteral orifice dilatation apart from 3 cases where another working guide wire was applied. No intraoperative complications were recorded in the form of mucosal injury, ureteral perforation, or urinary extravasation. There is no early postoperative complication in the form of urinary tract infection or colic apart from single case of hematuria which was successfully treated conservatively. Two weeks postoperatively, KUB (kidney, ureter, and bladder) films were completely free from any significant gravel (>3 mm) and US showed no hydronephrosis. Stentless ureteroscopic holmium laser disintegration without gravels removal is a safe and effective method for pediatric ureteral stone less than 10 mm in diameter.

  11. Variation in Sediment Mobility and the Active Width in Gravel-bed Braided Rivers

    NASA Astrophysics Data System (ADS)

    Peirce, S.; Leduc, P.; Ashmore, P.

    2016-12-01

    The complex and dynamic morphology of gravel-bed braided rivers is fundamentally a consequence of spatially and temporally variable sediment transport. For example, while braided rivers have multiple channels conveying water, few ( 1-2) channels convey sediment and only a narrow area (morphological active width) of those active channels transport bedload. To investigate the relationship between the morphological active width and bedload transport, a 1:30 physical-scale model of a gravel-bed river (D50 = 1.3mm) with adjustable discharge (0.7-2.1l/s) was used to simulate three experimental hydrographs. The physical model represents a braided river with 1.5% slope, medium gravel, and discharges between 4-13 m3s-1. High-resolution (± 1.15 mm) DEMs of the dry-bed surface were generated at 15 minute intervals using digital photogrammetry and the software program Agisoft PhotoScan. The morphological active width was quantified by subtracting successive DEMs to highlight areas and volumes of erosion and deposition. Bedload transport and grain size distribution were independently measured by accumulating bedload in baskets at the downstream outlet. Results show that while bedload transport and the active width are spatially and temporally variable, they both increase with increasing discharge above a lower threshold of 1.1l/s. Exceptions from this trend suggest that antecedent morphological conditions, such as migrating bars and bedload sheets, contribute to the inherent spatio-temporal variability. Grain size analysis shows that bedload transport moves from partial mobility towards equal mobility with increasing discharge, even in these dynamic multi-channel river systems. Understanding the relationships between channel morphology, bedload transport and mobility, and the active width will improve predictions of bedload transport rate in complex rivers and provide a more complete understanding of morph-dynamic processes in gravel-bed rivers.

  12. Surface particle sizes on armoured gravel streambeds: Effects of supply and hydraulics

    Treesearch

    Peter J. Whiting; John G. King

    2003-01-01

    Most gravel-bed streams exhibit a surface armour in which the median grain size of the surface particles is coarser than that of the subsurface particles. This armour has been interpreted to result when the supply of sediment is less than the ability of the stream to move sediment. While there may be certain sizes in the bed for which the supply is less than the...

  13. Reconstructing late Cenozoic stream gradients from high-level chert gravels in central Eastern Kansas

    USGS Publications Warehouse

    Harbaugh, J.W.; Merriam, D.F.; Howard, H.H.

    2007-01-01

    Interpreting the evolution of Kansas' landscape east of the Flint Hills provides major challenges. In the Neogene (late Tertiary) and perhaps part of the Pleistocene, streams transported a variety of sedimentary materials, including chert gravels derived from the Flint Hills. Gentle intermittent uplift stimulated the system system to cut down, locally removing and reworking the gravels to create stream-terrace deposits that consist mostly of chert pebbles, which now lie well above the floodplains of modern streams. By correlating the elevations of these gravels, the gradients of the trunk streams that deposited them can be reconstructed. Interestingly, these ancient streams flowed southeast at a little more than a foot per mile (0.2 m/km), roughly the same as the gradient of the trunk streams in the region today. The evolving landscape in eastern Kansas also has been strongly influenced by an extensive network of fractures that is widespread in the midcontinent region and may be worldwide in extent. In northeastern Kansas, glaciation during the Pleistocene disrupted the southeasterly drainage and established the present location of the Kansas River. South of the Kansas River and its immediate tributaries, however, the general southeasterly drainage has been preserved. We have made use of the wealth of topographic-elevation data now available in digital form known as DEMs or digital elevation models. Coupled with GIS procedures, the DEMs helped link the mapped distribution of chert gravels with hypothetical fitted surfaces that represent ancient stream gradients. Furthermore, DEM data placed in shaded-relief map form emphasize the influence of fractures in evolution of the drainage system.

  14. Friction angle measurements on a naturally formed gravel streambed: Implications for critical boundary shear stress

    Treesearch

    John M. Buffington; William E. Dietrich; James W. Kirchner

    1992-01-01

    We report the first measurements of friction angles for a naturally formed gravel streambed. For a given test grain size placed on a bed surface, friction angles varied from 10º to over 100º; friction angle distributions can be expressed as a function of test grain size, median bed grain size, and bed sorting parameter. Friction angles decrease with increasing grain...

  15. Topographic disturbance of subaqueous gravel substrates by signal crayfish ( Pacifastacus leniusculus)

    NASA Astrophysics Data System (ADS)

    Johnson, Matthew F.; Rice, Stephen P.; Reid, Ian

    2010-11-01

    The impact of signal crayfish ( Pacifastacus leniusculus) on the topography and fabric of six narrowly graded, gravel substrates was investigated using repeat laser scanning of sediment surfaces in still-water aquaria. Digital Elevation Models (DEMs) of the gravel surfaces were obtained before and after exposure to crayfish for five predetermined periods. The impact on the substrate was quantified by establishing topographic and volumetric changes using DEMs of difference (DoD). The presence of an individual, medium sized crayfish for 24 h resulted in an average volume change in surface topography of 450 cm 3 over an area of 2400 cm 2, giving a sediment displacement of 1.7 kg m -2 d - 1 . The majority (78%) of this volume change was associated with small scale (≤ 1 median grain diameter) movements of surface grains. This fabric adjustment altered grain orientations and friction angles. Crayfish also constructed pits and mounds that increased significantly the roughness of the gravel substrates and altered the protrusion of individual grains. Crayfish were able to move material up to 38 mm in diameter that had a submerged weight six times that of the individuals used in this study. By modifying the arrangement of grains on the surface of fluvial substrates, signal crayfish may counteract the low flow physical consolidation of gravel beds and reduce the entrainment stresses required to move river bed material. The results of this study suggest that signal crayfish, an internationally widespread invasive species, may have substantial impacts on the physical environment of streams and rivers, as well as on local benthic ecological communities.

  16. Tracing river gravels: Insights into dispersion from a long-term field experiment

    NASA Astrophysics Data System (ADS)

    Haschenburger, J. K.

    2013-10-01

    Sediment dispersion is a fundamental component of the sediment transfer process in gravel-bed rivers. Modeling this process requires an understanding of the collective movement of mixed-size clasts. This study explores the temporal evolution of gravel dispersion to underscore the importance of field observation in informing modeling efforts. Magnetically tagged gravels deployed in Carnation Creek have been monitored repeatedly over 17 years. Four metrics used to describe the extent of dispersion document that the overall shape in the spatial distribution of grain location changes over time. The general trends mask the complexity of the dispersion process, expressed by channel sections where tracers are concentrated regardless of grain size. The distribution of total grain displacement responsible for dispersion evolves as tracers become well mixed. Results demonstrate that observations from the field are crucial to the understanding and modeling of sediment dispersion because they provide key insights into the dispersion process that must be known a priori for mathematical modeling and similar observations cannot be collected using laboratory flumes.

  17. The grain size gap and abrupt gravel-sand transitions in rivers due to suspension fallout

    NASA Astrophysics Data System (ADS)

    Lamb, Michael P.; Venditti, Jeremy G.

    2016-04-01

    Median grain sizes on riverbeds range from boulders in uplands to silt in lowlands; however, rivers with ~1-5 mm diameter bed sediment are rare. This grain size gap also marks an abrupt transition between gravel- and sand-bedded reaches that is unlike any other part of the fluvial network. Abrupt gravel-sand transitions have been attributed to rapid breakdown or rapid transport of fine gravel, or a bimodal sediment supply, but supporting evidence is lacking. Here we demonstrate that rivers dramatically lose the ability to transport sand as wash load where bed shear velocity drops below ~0.1 m/s, forcing an abrupt transition in bed-material grain size. Using thresholds for wash load and initial motion, we show that the gap emerges only for median bed-material grain sizes of ~1-5 mm due to Reynolds number dependencies in suspension transport. The grain size gap, therefore, is sensitive to material properties and gravity, with coarser gaps predicted on Mars and Titan.

  18. Deschutes River Spawning Gravel Study, Volume II, Appendices I-XIV, Final Report.

    SciTech Connect

    Huntington, Charles W.

    1985-09-01

    Spawning habitat in the Deschutes River was inventoried, gravel permeability and composition were sampled at selected gravel bars, historical flow records for the Deschutes were analyzed, salmon and trout utilization of spawning habitat was examined, and potential methods of enhancing spawning habitat in the river were explored. Some changes in river conditions since the mid-1960's were identified, including a reduction in spawning habitat immediately downstream from the hydroelectric complex. The 1964 flood was identified as a factor which profoundly affected spawning habitat in the river, and which greatly complicated efforts to identify recent changes which could be attributed to the hydrocomplex. A baseline on present gravel quality at both chinook and steelhead spawning areas in the river was established using a freeze-core methodology. Recommendations are made for enhancing spawning habitat in the Deschutes River, if it is independently determined that spawning habitat is presently limiting populations of summer steelhead or fall chinook in the river. Volume II contains appendices to the study.

  19. Gravel and sand resources of the New England-New York region

    USGS Publications Warehouse

    Currier, Louis W.

    1955-01-01

    Deposits of sand and gravel are widespread in the New England-New York regions and constitute one of its principal mineral resources. Most of the pits are operated intermittently to supply local needs. Because of the great number and variety of known deposits, and because they have been worked at countless points it is impracticable to describe in detail either the deposits or the individual pits. On the other hand, a broad description of the geologic modes of occurrence with relation to the regional geology will serve adequately to indicate the importance of the resource in the regional economy and development. Except for some special sands, such as "glass sand", certain molding and foundry sands, et. al., for which restrictive textural, compositional and physical properties are required, sand and gravel are used chiefly for local construction and are not commonly transported for long distances. Sand and gravel deposits of the region fall into four principal genetic categories - e.g., glacial, alluvial, marine, and aeolian. Of these, deposits of glacial origin are by far the most widespread and important.

  20. Greywater treatment by granular filtration system using volcanic tuff and gravel media.

    PubMed

    Albalawneh, Abeer; Chang, Tsun-Kuo; Alshawabkeh, Heba

    2017-05-01

    The main objective of this study was to evaluate the efficiency of a granular filtration system (GFS) in greywater treatment under arid and semi-arid conditions. Six GFSs were designed, constructed, and monitored for approximately 13 months. Each GFS served a single rural Jordanian home by treating their greywater. Volcanic tuff media were used as the filtration media in three of the GFSs while the remaining three GFSs used gravel media. Results show that the biological oxygen demand, chemical oxygen demand, and total suspended solids of the effluent were significantly lower as compared to the influent and demonstrated a removal efficiency of 73%, 65%, and 85%, respectively, when using volcanic tuff media. The removal efficiency was 49%, 51%, and 76%, respectively, when using gravel media. There was a significant increase in the electrical conductivity, pH, potassium (K(+)), magnesium (Mg(2+)), chloride (Cl(-)), sodium (Na(+)), sulfate (SO4(2-)), bicarbonates (HCO3(-)), sodium adsorption ratio, and exchangeable sodium percentage in the effluents of the GFS that used volcanic tuff media. The study suggests that GFSs can adequately treat greywater under arid conditions. However, gravel media produce less concentrated effluent compared to the volcanic tuff media.

  1. Spatial and temporal variations of sediment size on a mixed sand and gravel beach

    NASA Astrophysics Data System (ADS)

    Horn, Diane P.; Walton, Susan M.

    2007-12-01

    Mixed sand and gravel beaches have been the subject of comparatively few studies in the UK. This paper describes the sediment distribution before, during and after a programme of beach nourishment along a section of mixed sand and gravel beach forming part of the Pevensey Bay Coastal Defences, in East Sussex, UK. The beach was recharged in September 2002, and beach profiles were measured along three cross-shore transects from August 2002 to February 2003. Sediment samples were taken along the transects between August and November 2002, and a total of 147 sediment samples were analysed, 40 before nourishment and 107 after nourishment. The majority of the sediment samples were strongly bimodal, with mean sizes varying between a minimum of 0.18 mm (2.48 ϕ) for the sand fraction and a maximum of 27 mm (- 4.74 ϕ) for the gravel. The recharge material was also bimodal but contained more fine sediment than the natural beach material, particularly on the upper beach. The recharge sediment had grain sizes and sorting similar to some of the natural material but lower bimodality parameters than any of the natural sediment. The sediment distributions after recharge contained significantly more fine sediment, particularly on the upper beach. Over time, the beach profile lowered and fine sediment appeared to be selectively transported seawards from the beachface.

  2. Evaluation of long-term bedload virtual velocity in gravel-bed rivers (Ardenne, Belgium)

    NASA Astrophysics Data System (ADS)

    Houbrechts, Geoffrey; Levecq, Yannick; Peeters, Alexandre; Hallot, Eric; Van Campenhout, Jean; Denis, Anne-Cécile; Petit, François

    2015-12-01

    In many gravel-bed rivers, bed material transfer has been interrupted or perturbed by anthropogenic activities. Currently, restoration projects are being conducted in many countries in order to re-establish bedload continuity. However, until now, few studies have provided indications of the velocity of bed material over the long-term (at least decade to century time-scale). In the context of river restoration projects (e.g. weir removal, addition of spawning gravel), these data are nevertheless crucial to predict the downstream propagation of the geomorphological and biological benefits (e.g. supply-transport equilibrium, morphological and substratum diversity). In our study, PIT-tag tracers were used in eight medium-sized gravel-bed rivers (Ardenne Region, Belgium) to propose a flow competence relationship based on specific stream power, on the one hand, and to determine the long-term virtual velocity of the bed material corresponding to the median diameter (D50) of the surface layer of riffles, on the other hand. After each flow event that exceeded the threshold for sediment entrainment, tagged particles were sought and located, even when they were buried in the subsurface layer. Afterwards, all of the data were used to estimate the virtual velocity of the bed material over the long-term using three approaches. Finally, the results were compared with long-term transport estimations based on iron slag dispersed by the rivers since the end of the middle ages.

  3. Laboratory evidence for short and long-term damage to pink salmon incubating in oiled gravel

    SciTech Connect

    Heintz, R.; Rice, S.; Wiedmer, M.

    1995-12-31

    Pink salmon, incubating in gravel contaminated with crude oil, demonstrated immediate and delayed responses in the laboratory at doses consistent with the concentrations observed in oiled streams in Prince William Sound. The authors incubated pink salmon embryos in a simulated intertidal environment with gravel contaminated by oil from the Exxon Valdez. During the incubation and emergence periods the authors quantified dose-response curves for characters affected directly by the oil. After emergence, fish were coded wire tagged and released, or cultured in netpens. Delayed responses have been observed among the cultured fish, and further observations will be made when coded wire tagged fish return in September 1995. The experiments have demonstrated that eggs need not contact oiled gravel to experience increased mortality, and doses as low as 17 ppb tPAH in water can have delayed effects on growth. A comparison of sediment tPAH concentrations from streams in Prince William Sound with these laboratory data suggests that many 1989 brood pink salmon were exposed to deleterious quantities of oil.

  4. Utilization of LANDSAT multispectral data in geobotanical investigations: The location of ironstone gravel in the Sam Houston National Forest

    NASA Technical Reports Server (NTRS)

    Cibula, W. G.

    1982-01-01

    Practical techniques were developed and evaluated for deriving geobotanical information from LANDSAT MSS data acquired for a test site in the Sam Houston National Forest near Cleveland, Texas where gravel deposits exist in sufficient quantity that economical extraction would be feasible. A correlation was shown between a single spectral class and the presence of ironstone gravel. Field data indicates that this class relates to upland pine which was probably under stress as the result of a prolonged drought which was in progress at the time of data acquisition. It is suggested that the subsurface gravel produces a soil which has less field capacity for water retention, causing early appearance of water stress in the surface vegetation over these soils. In all areas within the QMC formation where this class occurred, gravel was located when borings were made.

  5. Spatial Dynamics of Gravel Bedload Transport Between a Pool-Exit Slope and the Head of a Point-Bar

    NASA Astrophysics Data System (ADS)

    Bunte, K.; Abt, S. R.

    2004-12-01

    Spatial dynamics of gravel transport in mountain streams are not well known. Results compiled from different streams suggest that the path of gravel transport in coarse-bedded streams with a meandering thalweg follows the path described for the coarsest bedload in sand-bedded meandering streams. From the thalweg in the pool exit slope, gravel moves laterally over the downstream riffle to reach the head of the next point bar. Gravel then proceeds across the bar towards the thalweg and into the pool. If proven correct, this finding has important implications for bedload sampling in partially wadable streams. Sampling could be limited to the bar head where equipment requiring wadable flows can be used, while still collecting the majority of gravel transported. To confirm the travel path between the pool exit and the head of the next bar, gravel transport was measured in a Colorado mountain stream in two cross-sections less than 10 m apart: one at a pool exit with the thalweg near the stream center and one at the bar head with the thalweg hugging the left bank. Six bedload traps were installed in each cross-section. The lateral location of maximum gravel transport differed greatly between the two cross-sections. In the pool exit, most of the transport occurred just to the right of the thalweg. In the bar cross-section, transport was absent in the left bank thalweg where flow was deepest and fastest but focused on the bankward side of the bar where flow was much shallower and slower, and with increasing flows the location of maximum gravel transport moved progressively further up the bar. Movement of tracer particles placed at several locations across the pool exit confirmed that most of the particles take a curved path and move onto the bar head and towards the bankward side of the bar. The bedload rating curve on the bar head was found to be better defined and steeper than the curve measured in the pool exit and the curves crossed at about half the measured maximum

  6. Adaptive radiation of gobies in the interstitial habitats of gravel beaches accompanied by body elongation and excessive vertebral segmentation

    PubMed Central

    Yamada, Tomohiko; Sugiyama, Tomoshige; Tamaki, Nana; Kawakita, Atsushi; Kato, Makoto

    2009-01-01

    Background The seacoasts of the Japanese Arc are fringed by many gravel beaches owing to active tectonic uplift and intense denudation caused by heavy rainfall. These gravel beaches are inhabited by gobies of the genus Luciogobius that burrow into the gravel sediment and live interstitially. Although their habitat and morphology (e. g., reduced fins, elongated, scale-less body, and highly segmented vertebral column) are highly unusual among fishes, little is known on how their morphological evolution has facilitated the colonization of interstitial habitats and promoted extensive diversification. We conducted thorough sampling of Luciogobius and related species throughout Japan, and performed molecular phylogenetic analysis to explore the patterns of morphological evolution associated with gravel beach colonization. Results An analysis of the mitochondrial cytochrome b gene suggested a remarkable diversity of previously unrecognized species. The species-level phylogeny based on six protein-coding nuclear genes clearly indicated that interstitial species cluster into two distinct clades, and that transitions from benthic or demersal habits to interstitial habits are strongly correlated with an increase in vertebral number. Colonization of gravel beach habitats is estimated to have occurred ca. 10 Ma, which coincides with the period of active orogenesis of the Japanese landmass. Different species of interstitial Luciogobius inhabit sediments with different granulometric properties, suggesting that microhabitat partitioning has been an important mechanism facilitating speciation in these fishes. Conclusion This is the first study to document the adaptation to interstitial habitats by a vertebrate. Body elongation and excessive vertebral segmentation had been the key aspects enhancing body flexibility and fishes' ability to burrow into the gravel sediment. The rich diversity of coastal gravel habitats of the Japanese Arc has likely promoted the adaptive radiation of

  7. Sheet-gravel evidence for a late Holocene tsunami run-up on beach dunes, Great Barrier Island, New Zealand

    NASA Astrophysics Data System (ADS)

    Nichol, Scott L.; Lian, Olav B.; Carter, Charles H.

    2003-01-01

    A semi-continuous sheet of granule to cobble-size clasts forms a distinctive deposit on sand dunes located on a coastal barrier in Whangapoua Bay, Great Barrier Island, New Zealand. The gravel sheet extends from the toe of the foredune to 14.3 m above mean sea level and 200 m landward from the beach. Clasts are rounded to sub-rounded and comprise lithologies consistent with local bedrock. Terrestrial sources for the gravel are considered highly unlikely due to the isolation of the dunes from hillslopes and streams. The only source for the clasts is the nearshore to inner shelf of Whangapoua Bay, where gravel sediments have been previously documented. The mechanism for transport of the gravel is unlikely to be storm surge due to the elevation of the deposit; maximum-recorded storm surge on this coast is 0.8 m above mean high water spring tide. Aeolian processes are also discounted due to the size of clasts and the elevation at which they occur. Tsunami is therefore considered the most probable mechanism for gravel transport. Minimum run-up height of the tsunami was 14.3 m, based on maximum elevation of gravel deposits. Optical ages on dune sands beneath and covering the gravel allow age bracketing to 0-4.7 ka. Within this time frame, numerous documented regional seismic and volcanic events could have generated the tsunami, notably submarine volcanism along the southern Kermadec arc to the east-southeast of Great Barrier Island where large magnitude events are documented for the late Holocene. Radiocarbon ages on shell from Maori middens that appear to have been reworked by tsunami run-up constrain the age of this event to post ca. 1400 AD. Regardless of the precise age of this event, the well-preserved nature of the Whangapoua gravel deposit provides for an improved understanding of the high degree of spatial variability in tsunami run-up.

  8. Measuring Gravel Transport in an Active Natural System: An Analytical Framework

    NASA Astrophysics Data System (ADS)

    Sanfilippo, J. D.; Lancaster, S. T.

    2014-12-01

    In order to measure sediment flux in Porter Creek, a small tributary to the North Fork of the Siuslaw River near Florence Oregon, we have deployed ~600 pieces of tracer gravel embedded with passive integrated transponder (PIT) tags, 8 fixed antennas, and 9 logging pressure transducers spaced along 130 m of channel comprising 3 wood jams and substrates of sand, gravel, cobble, and bedrock. Tracer deployment is uniform along the instrumented reach, analogous to constant-source solute or dye injection, so that sediment flux [L3/T] for the ith grain size class is Qi = niVpiFi/fTi, where ni is count rate, [T-1], Vpi is particle volume, and Fi and fTi are fractional coverage of the ith size class of grains and tracers, respectively. Tracer concentrations, fTi, must be large enough for accurate estimation of ni = 1/TAi where TAi is the mean inter-arrival time of tracers at an antenna, during a period of nearly constant discharge. A square wave or constant sediment injection is undertaken by placing a concentration of tracers dispersed upstream of the study reach, such that it will add to the concentration within the study reach as gravels migrate downstream, replacing the gravels within the antenna network. Preliminary results show dispersion values ranging from ~7 m2/month for 8-16mm size fraction, to ~0.2 m2/month for 32-64mm size fraction, with travel distances of 60 meters for the 8-16mm, 16 meters for the 16-32mm, 8 meters for the 32-64mm, and 4 meters for the >64mm for 1 water year. Since there is a high level of variability in dispersion within the antennae array given the heterogeneity of substrates and wood placed within the system, it is likely that some tracers will need to be added within the regions between antennae after high water events. The tracer concentration within the regions occupied between antennae must remain at such a level as to provide viable statistical relationships between tracer and non-tracer gravels, and percent mobile versus percent

  9. Wall-Friction Support of Vertical Loads in Submerged Sand and Gravel Columns

    SciTech Connect

    Walton, O. R.; Vollmer, H. J.; Hepa, V. S.

    2015-08-25

    Laboratory studies of the ‘floor-loads’ under submerged vertical columns of sand and/or gravel indicate that such loads can be approximated by a buoyancy-corrected Janssen-silo-theory-like relationship. Similar to conditions in storage silos filled with dry granular solids, most of the weight of the sand or gravel is supported by wall friction forces. Laboratory measurements of the loads on the floor at the base of the water-filled columns (up to 25-diameters tall) indicate that the extra floor-load from the addition of the granular solid never exceeded the load that would exist under an unsupported (wide) bed of submerged sand or gravel that has a total depth corresponding to only two column-diameters. The measured floorloads reached an asymptotic maximum value when the depth of granular material in the columns was only three or four pipe-diameters, and never increased further as the columns were filled to the top (e.g. up to heights of 10 to 25 diameters). The floor-loads were stable and remained the same for days after filling. Aggressive tapping (e.g. hitting the containing pipe on the outside, manually with a wrench up and down the height and around the circumference) could increase (and occasionally decrease) the floor load substantially, but there was no sudden collapse or slumping to a state without significant wall friction effects. Considerable effort was required, repeatedly tapping over almost the entire column wall periphery, in order to produce floor-loads that corresponded to the total buoyancy-corrected weight of granular material added to the columns. Projecting the observed laboratory behavior to field conditions would imply that a stable floor-load condition, with only a slightly higher total floor pressure than the preexisting hydrostatic-head, would exist after a water-filled bore-hole is filled with sand or gravel. Significant seismic vibration (either a large nearby event or many micro-seismic events over an extended period) would likely

  10. Gravel-Sand-Clay Mixture Model for Predictions of Permeability and Velocity of Unconsolidated Sediments

    NASA Astrophysics Data System (ADS)

    Konishi, C.

    2014-12-01

    Gravel-sand-clay mixture model is proposed particularly for unconsolidated sediments to predict permeability and velocity from volume fractions of the three components (i.e. gravel, sand, and clay). A well-known sand-clay mixture model or bimodal mixture model treats clay contents as volume fraction of the small particle and the rest of the volume is considered as that of the large particle. This simple approach has been commonly accepted and has validated by many studies before. However, a collection of laboratory measurements of permeability and grain size distribution for unconsolidated samples show an impact of presence of another large particle; i.e. only a few percent of gravel particles increases the permeability of the sample significantly. This observation cannot be explained by the bimodal mixture model and it suggests the necessity of considering the gravel-sand-clay mixture model. In the proposed model, I consider the three volume fractions of each component instead of using only the clay contents. Sand becomes either larger or smaller particles in the three component mixture model, whereas it is always the large particle in the bimodal mixture model. The total porosity of the two cases, one is the case that the sand is smaller particle and the other is the case that the sand is larger particle, can be modeled independently from sand volume fraction by the same fashion in the bimodal model. However, the two cases can co-exist in one sample; thus, the total porosity of the mixed sample is calculated by weighted average of the two cases by the volume fractions of gravel and clay. The effective porosity is distinguished from the total porosity assuming that the porosity associated with clay is zero effective porosity. In addition, effective grain size can be computed from the volume fractions and representative grain sizes for each component. Using the effective porosity and the effective grain size, the permeability is predicted by Kozeny-Carman equation

  11. Comparison of the catabolic activity and catabolic profiles of rhizospheric, gravel-associated and interstitial microbial communities in treatment wetlands.

    PubMed

    Weber, Kela P; Legge, Raymond L

    2013-01-01

    Microbial communities play a critical role in degrading organic contaminants in treatment wetlands; however, an understanding of the different roles played by rhizospheric, gravel-associated and interstitial microbial communities is deficient due to a lack of data directly comparing these microbial communities. Community level physiological profiling (CLPP) was used to compare the catabolic capabilities of rhizospheric, gravel-associated and interstitial microbial communities in vertical-flow planted and unplanted wetland mesocosms. Wetland mesocosms were decommissioned to gather microbial community samples associated with the roots and gravel bed media taken from the top (10 cm depth), middle (30 cm depth) and bottom (60 cm depth). The catabolic capabilities of the rhizospheric microbial communities were seen to be much greater than those of the gravel-associated communities. A decrease in catabolic capability was seen with increasing depth, suggesting that communities near the surface play a larger role in the degradation of carbon-based compounds. A general difference in catabolic profiles based on plant presence/absence was observed for the interstitial water and all gravel-associated samples at all depths, suggesting that the presence of roots within part of the mesocosm not only has a localized effect on the attached microbial population, but also on gravel-associated microbial communities throughout the mesocosms.

  12. Formation of gravel pavements during fluvial erosion as an explanation for persistence of ancient cratered terrain on Titan and Mars

    NASA Astrophysics Data System (ADS)

    Howard, Alan D.; Breton, Sylvain; Moore, Jeffrey M.

    2016-05-01

    In many terrestrial channels the gravel bed is only transported during rare floods (threshold channels), and rates of erosion are very slow. In this paper we explore how coarse debris delivered to channels on Mars and Titan from erosion may inhibit further erosion once a coarse gravel channel bed develops. Portions of the equatorial region of Titan are fluvially eroded into banded (crenulated) terrain, some of which contains numerous circular structures that are likely highly degraded large impact craters surviving from the late heavy bombardment. No mechanism that can chemically or physically break down ice (likely the most important component of Titans crust) has been unambiguously identified. This paper examines a scenario in which fluvial erosion on Titan has largely involved erosion into an impact-generated megaregolith that contains a modest component of gravel-sized debris. As the megaregolith is eroded, coarse gravel gradually accumulates as a lag pavement on channel beds, limiting further erosion and creating a dissected, but largely inactive, or senescent, landscape. Similar development of gravel pavements occur in ancient mountain belts on Earth, and partially explain the persistence of appreciable relief after hundreds of millions of years. Likewise, coarse gravel beds may have limited the degree to which erosion could modify the heavily cratered terrains on Mars, particularly if weathering were largely due to physical, rather than chemical weathering processes in a relatively cold and/or arid environment.

  13. Geomorphic Effects of Boulder Placement on Gravel Capture and Retention in a Regulated Reach of the North Umpqua River, OR.

    NASA Astrophysics Data System (ADS)

    Stallman, J.; Braudrick, C.; Pedersen, D.; Cui, Y.; Sklar, L.; Dietrich, B.; Real de Asua, R.

    2004-12-01

    Hydroelectric projects in the mountainous western Cascades often occur in steep, confined channels where salmonid spawning habitat is limited to gravel deposits forced by planform curvature, channel width changes, and flow separation associated with large bedrock and boulder obstructions. The paucity of gravel deposition in steepland channels may be exacerbated in regulated rivers where sediment trapping by impoundments reduces coarse sediment supply to downstream reaches. Placing boulders to capture and retain gravel may be an effective approach to enhancing spawning habitat in these settings. To better understand the potential use of boulders as a tool for enhancing spawning habitat, three experimental designs were tested in a 0.6-mile bypass reach of the North Umpqua River, OR. The bedrock-confined study reach has an average slope of 0.013 and plane-bed morphology with coarse cobble substrate, abundant marginal boulders, and small associated patches of sand and gravel. Experiments involved (1) placement of boulder clusters, (2) gravel augmentation and placement of boulder clusters, and (3) gravel augmentation alone. Boulder clusters were designed to promote scour and deposition during floods with a 5-10 year recurrence interval. Boulders were typically placed obliquely upstream at locations where existing hydraulics favored gravel deposition. Monitoring from 2002 to 2004 occurred prior to implementation, immediately following implementation, and following winter high flows. Sites were monitored using high-density topographic surveys, low-altitude aerial photography, facies mapping, pebble counts, scour cores and chains, and marked rocks. Stage heights were monitored using pressure transducers at the upstream and downstream ends of the study reach, and flood recurrence interval was assessed using a nearby USGS gauge. The arrangement of boulder clusters was modified after the first year of monitoring to improve gravel capture and retention. Peak flow during the

  14. An evaluation of sand and gravel resources in and near the Prescott National Forest in the Verde Valley, Arizona; with a section on evaluation of sand and gravel resources using selected engineering variables

    USGS Publications Warehouse

    Cox, Leslie J.; Bliss, James D.; Miller, Robert J.

    1999-01-01

    This study was based on available published literature. Although no field investigation was conducted in the Prescott National Forest to the west of the Verde River, a field investigation was conducted in the summer of 1994 by this author on the Coconino National Forest, to the east of the Verde River, where units of surficial materials of the same age and similar character are found (Cox, 1995). The intent of this evaluation of sand and gravel resources in the Prescott National Forest and adjacent areas in the Verde Valley, is to provide the land managers of the U.S. Forest Service with a map that delineates sand- and gravel-bearing geologic units. The map distinguishes (1) sand-and gravel-bearing units that are limited to channels from those that are not, (2) sand-and gravel-bearing units that are thin (generally less than 40 feet thick which is one contour interval on the topographic maps) from those that are locally thick (generally 40 feet or more), (3) sand- and gravel-bearing units that are poorly sorted from those that are well-sorted4, (4) sand- and gravel-bearing units that have little or no soil development from those that have greater degrees of soil development and lithification, (5) and sand- and gravel-bearing units that support riparian vegetation from those that do not. These distinctive characteristics are related to the geologic age or depositional setting of the rock materials and can be distinguished where areas are mapped in detail.

  15. Treatment of heavy metals by iron oxide coated and natural gravel media in Sustainable urban Drainage Systems.

    PubMed

    Norris, M J; Pulford, I D; Haynes, H; Dorea, C C; Phoenix, V R

    2013-01-01

    Sustainable urban Drainage Systems (SuDS) filter drains are simple, low-cost systems utilized as a first defence to treat road runoff by employing biogeochemical processes to reduce pollutants. However, the mechanisms involved in pollution attenuation are poorly understood. This work aims to develop a better understanding of these mechanisms to facilitate improved SuDS design. Since heavy metals are a large fraction of pollution in road runoff, this study aimed to enhance heavy metal removal of filter drain gravel with an iron oxide mineral amendment to increase surface area for heavy metal scavenging. Experiments showed that amendment-coated and uncoated (control) gravel removed similar quantities of heavy metals. Moreover, when normalized to surface area, iron oxide coated gravels (IOCGs) showed poorer metal removal capacities than uncoated gravel. Inspection of the uncoated microgabbro gravel indicated that clay particulates on the surface (a natural product of weathering of this material) augmented heavy metal removal, generating metal sequestration capacities that were competitive compared with IOCGs. Furthermore, when the weathered surface was scrubbed and removed, metal removal capacities were reduced by 20%. When compared with other lithologies, adsorption of heavy metals by microgabbro was 10-70% higher, indicating that both the lithology of the gravel, and the presence of a weathered surface, considerably influence its ability to immobilize heavy metals. These results contradict previous assumptions which suggest that gravel lithology is not a significant factor in SuDS design. Based upon these results, weathered microgabbro is suggested to be an ideal lithology for use in SuDS.

  16. The Lilesville Gravels: A Neogene Strath Terrace Deposit from the Piedmont/Coastal Plain Boundary of North Carolina, USA

    NASA Astrophysics Data System (ADS)

    Diemer, J. A.; McLean, R.; Bobyarchick, A. R.; Xanthos, G.

    2015-12-01

    The Lilesville "gravels" are discontinuous Neogene cobble, sand and silt deposits exposed in gravel quarries in an area covering ~100 km2 where the Pee Dee River crosses the Fall Line of North Carolina. These deposits unconformably overlie the western edge of the Inner Coastal Plain, and parts of the saprolitized Paleozoic Lilesville pluton, and are interpreted as strath terrace deposits. In the Bonsal quarry, the Lilesville "gravels" comprise channel fills, channel bars, pebble lags, trough cross bedding, mud clasts, and mud drapes. These features define several facies including: 1) an imbricated clast-supported conglomerate with a medium- to coarse-grained lithic arenite matrix; 2) a lenticular silt- to medium-grained lithic arenite partly interbedded with the conglomerate; 3) a pebbly cross-bedded medium- to coarse-grained lithic arenite; and 4) a mottled medium- to coarse-grained lithic arenite. Paleoflow indicators suggest southerly transport, parallel to the modern Pee Dee River. GPR profiles and 3D models document facies boundaries on the quarry face and behind the high-wall. The tops of the Lilesville "gravels" are commonly marked by a pebble lag (deflation) horizon disconformably overlain by a medium- to coarse-grained, well-sorted quartz arenite interpreted as an aeolian deposit (Pinehurst Fm?). C14 dates from charcoal in the aeolian sand are 1638 +/- 46 calendar years BP (or 312 AD +/- 46). The age of the Lilesville "gravels" remains uncertain. However, by using regional curves for ages of terrace deposits relative to their heights above river level (Mills 2000), it is suggested here that the Lilesville gravels are 7 to 12 Ma (Upper Miocene). It is likely that the Lilesville "gravels" were deposited by the ancestral Pee Dee River when it was a braided stream flowing in a southerly direction. This suggests that a combination of regional uplift and a wetter paleoclimate in the Late Miocene may have been responsible for a larger discharge and coarser

  17. The role of a coarse surface layer in impeding evaporation from gravel bars

    NASA Astrophysics Data System (ADS)

    Edmaier, Katharina; Peter, Molnar; Clémentine, Cyprien; Paolo, Burlando

    2010-05-01

    The presence of a coarse surface layer (CSL) on bars in gravel bed rivers is expected to have an influence on evaporation rates from these surfaces and thereby on the water content in the underlying gravel-sand matrix. A statistically significant increase in soil water content in the presence of a CSL has recently been demonstrated in outdoor experiments by Meier and Hauer (2010). The authors argued that the CSL leads to a reduction in available energy for evaporation, decreases the advection of water vapour from the evaporating surface and reduces the supply of water from the underlying matrix to the evaporating surface. These findings are important because the germination of seeds and vegetative reproduction of riparian species on gravel bars are presumed to be driven by local soil moisture availability. Therefore local conditions of erosion-deposition which lead to the presence or absence of a CSL could be a crucial parameter for successful vegetation establishment on gravel bars. We conducted a simple laboratory experiment to verify the findings of Meier and Hauer (2010) under more controlled conditions. In the experiment 6 cylindrical buckets with a surface area of 720 cm2 and total volume of 19500 cm3 were filled with a sand-gravel mixture to replicate the sediment composition in the Thur River, Switzerland (d50 = 8 mm). This site is part of the research project RECORD (www.record.ethz.ch), which focuses on river restoration issues. Three treatments were investigated, each with a CSL of different thickness (H = 0, 40 and 80 mm) with one replicate each, roughly corresponding to 2 and 4 layers of typical CSL gravel diameters in the Thur River. We also measured the temperature in the sediment matrix underneath the CSL. The samples were saturated over several days and subsequently gravitationally drained in order to retain water held only by capillary forces as the initial condition. The samples were then weighed daily for 47 days and the evaporation rates and

  18. Gravel bar thermal variability and its potential consequences for CO2 evasion from Alpine coldwater streams

    NASA Astrophysics Data System (ADS)

    Boodoo, Kyle; Battin, Tom; Schelker, Jakob

    2017-04-01

    Gravel bars (GB) are ubiquitous in-stream structures with relatively large exposed surfaces, capable of absorbing heat and possibly acting as a heat source to the underlying hyporheic zone (HZ). The distinctive mixing of groundwater and surface water within their HZ largely determines its characteristic physical and biogeochemical properties, including temperature distribution. To study thermal variability within GBs and its possible consequences for CO2 evasion fluxes we analysed high frequency spatio-temporal data for a range of stream and atmospheric physical parameters including the vertical GB temperature, in an Alpine cold water stream (Oberer Seebach, Austria) over the course of a year. We found the vertical temperature profiles within the GB to vary seasonally and with discharge. We extended our study to 13 other gravel bars of varying physical characteristics within the surrounding Ybbs and Erlauf catchments, conducting diurnal spot samplings in summer 2016. Temperatures within the observed permanently wetted hyporheic zone (-56 to -100cm depth below GB surface) of the OSB, were warmer than both end members, surface water and groundwater >18% of the year, particularly during summer. There was a general increase in exceedance within the periodically wetted gravel bar sediment toward the gravel bar surface, further evidencing downward heat transfer to the wetted HZ. Average CO2 flux from the GB was significantly higher than that of streamwater during summer and winter, with significantly higher temperatures and CO2 outgassing rates occurring at the GB tail as compared to streamwater and the head and mid of the GB throughout the year. Higher cumulative (over 6 h) GB seasonal temperatures were associated with increased CO2 evasion fluxes within the OSB, particularly during summer. This enhanced CO2 flux may result from the input of warmer CO2-rich groundwater into the HZ in autumn, while downward heat transfer in summer may enhance GB metabolism and therefore

  19. Edge Effects Are Important in Supporting Beetle Biodiversity in a Gravel-Bed River Floodplain

    PubMed Central

    Langhans, Simone D.; Tockner, Klement

    2014-01-01

    Understanding complex, dynamic, and diverse ecosystems is essential for developing sound management and conservation strategies. Gravel-bed river floodplains are composed of an interlinked mosaic of aquatic and terrestrial habitats hosting a diverse, specialized, and endangered fauna. Therefore, they serve as excellent models to investigate the biodiversity of multiple ecotones and related edge effects. In this study, we investigated the abundance, composition, richness, and conservation status of beetle assemblages at varying sediment depth (0, 0.1, 0.6 and 1.1 m), distance from the channel (1, 5, 20, and 60–100 m, and 5 m within the riparian forest), and time of the year (February–November) across a 200 m-wide gravel bar at the near-natural Tagliamento River (Italy), to detect edge effects in four floodplain ecotones: aquatic-terrestrial, forest-active floodplain, sediment-air, and sediment-groundwater. We used conventional pitfall traps and novel tube traps to sample beetles comparably on the sediment surface and within the unsaturated sediments. We found a total of 308 beetle species (including 87 of conservation concern) that showed multiple, significant positive edge effects across the floodplain ecotones, mainly driven by spatial heterogeneity: Total and red list beetle abundance and richness peaked on the sediment surface, at channel margins, and at the edge of the riparian forest. All ecotones possessed edge/habitat specialists. Most red list species occurred on the sediment surface, including five species previously considered extinct – yet two of these species occurred in higher densities in the unsaturated sediments. Conservation and management efforts along gravel-bed rivers must therefore promote a dynamic flow and sediment regime to create and maintain habitat heterogeneity and ecotone diversity, which support a unique and high biodiversity. PMID:25545280

  20. Activation Pattern of Lower Leg Muscles in Running on Asphalt, Gravel and Grass.

    PubMed

    Dolenec, Aleš; Štirn, Igor; Strojnik, Vojko

    2015-07-01

    Running is performed on different natural surfaces (outdoor) and artificial surfaces (indoor). Different surface characteristics cause modification of the lower leg muscle activation pattern to adopt ankle stiffness to these characteristics. So the purpose of our investigation was to study changes of lower leg muscles activation pattern in running on different natural running surfaces. Six male and two female runners participated. The participants ran at a freely chosen velocity in trials on asphalt while in trials on gravel, and grass surfaces they were attempting to reach similar velocities as in the trials on asphalt. Muscle activation of the peroneus brevis, tibialis anterior, soleus, and gastrocnemius medialis of the right leg was recorded. Running on asphalt increased average EMG amplitude of the m. tibialis anterior in the pre-activation phase and the m. gastrocnemius medialis in the entire contact phase compared to running on grass from 0.222 ± 0.113 V to 0.276 ± 0.136 V and from 0.214 ± 0.084 V to 0.238 ± 0.088 V, respectively. The average EMG of m. peroneus brevis in pre-activation phase increased from 0.156 ± 0.026 V to 0.184 ± 0.455 V in running on grass in comparison to running on gravel. Running on different surfaces is connected with different activation patterns of lower leg muscles. Running on asphalt requires stiff ankle joints, running on gravel requires greater stability in ankle joints, while running on grass is the least demanding on lower leg muscles.

  1. Gravel transport by ice in a subarctic river from accurate laser scanning

    NASA Astrophysics Data System (ADS)

    Lotsari, Eliisa; Wang, Yunsheng; Kaartinen, Harri; Jaakkola, Anttoni; Kukko, Antero; Vaaja, Matti; Hyyppä, Hannu; Hyyppä, Juha; Alho, Petteri

    2015-10-01

    For decades the importance of ice and the effects of cold-region processes on river channel morphology have been discussed, with a general consensus as to their importance emerging only recently. River ice cover, anchor ice, frazil ice, and ice jams may not only scour the channel bed and banks but also pick up, transport, and deposit fine sediments and gravels during winter, especially during the spring ice breakup period. However, knowledge of the interactions between coarse sediment transport and ice processes remains insufficient, particularly in rockier river reaches, with a lack of accurate and sufficiently extensive data hindering their quantification. The aim of this study was to quantify and analyse the impact of river ice on gravel transport in a subarctic river during one winter via the acquisition of laser scanning data for the river channel and ice surface. Terrestrial and mobile laser scanning were performed in 2012-2013 on the Tana River in northern Finland. Both of these techniques are considered accurate and applicable for detecting elevation and volumetric changes in river bed, defining gravel clast sizes, and detecting the movement of individual clasts. More importantly, ice surface, thickness, and decay during spring were also captured via laser scanning. In the winter of 2012-2013, a period characterised by an absence of ice jams and mid-winter ice-decay periods, with spring ice breakup discharges close to average yearly conditions, ice had the most significant role, greater than that of flowing water, in erosion and transport of coarse sediment from the channel bed and gently sloping banks. Changes in river bed elevation and volume were recorded throughout the study site, and erosion predominated. In addition to broader scale erosion, the movement of single clasts up to 2 m in size occurred. However, the observed overall channel change patterns did not coincide with the areas of fastest ice decay. The obtained results could also be applied to

  2. Sediment routing through channel confluences: RFID tracer experiments from a gravel-bed river headwaters

    NASA Astrophysics Data System (ADS)

    Imhoff, K.; Wilcox, A. C.

    2014-12-01

    Tributary confluences may significantly impact large-scale patterns of sediment transport because of their role in connecting individual streams in a network. These unique locations feature complex flow structures and geomorphic features, and may represent ecological hotspots. Sediment transport across confluences is poorly understood, however. We present research on coarse sediment transport and dispersion through confluences using sediment tracers in the East Fork Bitterroot River, Montana, USA. We tagged a range of gravel (>40 mm) and cobble particles with Radio Frequency Identification (RFID) tags and painted smaller (10-40 mm) gravels, and then we traced them through confluences in a montane river's headwaters. We measured the effects of confluences on dispersion, path length, and depositional location and compare properties of sediment routing with a non-confluence control reach. We also measured topographic change through repeat bed surveys and combined topography, hydraulics, and tracer measurements to calculate basal shear and critical Shields stresses for different grain sizes. Field observations suggest that tagged particles in confluences routed along flanks of scour holes in confluences, with sediment depositing further downstream along bank-lateral bars than within the channel thalweg. Travel distances of RFID-tagged particles ranged up to 35 meters from original seeding points, with initial recovery rates of RFID-tagged tracers ranging between 84-89%. In both confluence and control reaches only partial mobility was observed within the entire tracer population, suggesting a hiding effect imposed by the roughness of the bed. Particles seeded in the channel thalweg experienced further travel distances than those seeded towards the banks and on bars. Differences in dispersion between confluence and control reaches are implied by field observation. This study quantified patterns of sediment routing within confluences and provided insight to the importance

  3. Can high resolution 3D topographic surveys provide reliable grain size estimates in gravel bed rivers?

    NASA Astrophysics Data System (ADS)

    Pearson, E.; Smith, M. W.; Klaar, M. J.; Brown, L. E.

    2017-09-01

    High resolution topographic surveys such as those provided by Structure-from-Motion (SfM) contain a wealth of information that is not always exploited in the generation of Digital Elevation Models (DEMs). In particular, several authors have related sub-metre scale topographic variability (or 'surface roughness') to sediment grain size by deriving empirical relationships between the two. In fluvial applications, such relationships permit rapid analysis of the spatial distribution of grain size over entire river reaches, providing improved data to drive three-dimensional hydraulic models, allowing rapid geomorphic monitoring of sub-reach river restoration projects, and enabling more robust characterisation of riverbed habitats. However, comparison of previously published roughness-grain-size relationships shows substantial variability between field sites. Using a combination of over 300 laboratory and field-based SfM surveys, we demonstrate the influence of inherent survey error, irregularity of natural gravels, particle shape, grain packing structure, sorting, and form roughness on roughness-grain-size relationships. Roughness analysis from SfM datasets can accurately predict the diameter of smooth hemispheres, though natural, irregular gravels result in a higher roughness value for a given diameter and different grain shapes yield different relationships. A suite of empirical relationships is presented as a decision tree which improves predictions of grain size. By accounting for differences in patch facies, large improvements in D50 prediction are possible. SfM is capable of providing accurate grain size estimates, although further refinement is needed for poorly sorted gravel patches, for which c-axis percentiles are better predicted than b-axis percentiles.

  4. Edge effects are important in supporting beetle biodiversity in a gravel-bed river floodplain.

    PubMed

    Langhans, Simone D; Tockner, Klement

    2014-01-01

    Understanding complex, dynamic, and diverse ecosystems is essential for developing sound management and conservation strategies. Gravel-bed river floodplains are composed of an interlinked mosaic of aquatic and terrestrial habitats hosting a diverse, specialized, and endangered fauna. Therefore, they serve as excellent models to investigate the biodiversity of multiple ecotones and related edge effects. In this study, we investigated the abundance, composition, richness, and conservation status of beetle assemblages at varying sediment depth (0, 0.1, 0.6 and 1.1 m), distance from the channel (1, 5, 20, and 60-100 m, and 5 m within the riparian forest), and time of the year (February-November) across a 200 m-wide gravel bar at the near-natural Tagliamento River (Italy), to detect edge effects in four floodplain ecotones: aquatic-terrestrial, forest-active floodplain, sediment-air, and sediment-groundwater. We used conventional pitfall traps and novel tube traps to sample beetles comparably on the sediment surface and within the unsaturated sediments. We found a total of 308 beetle species (including 87 of conservation concern) that showed multiple, significant positive edge effects across the floodplain ecotones, mainly driven by spatial heterogeneity: Total and red list beetle abundance and richness peaked on the sediment surface, at channel margins, and at the edge of the riparian forest. All ecotones possessed edge/habitat specialists. Most red list species occurred on the sediment surface, including five species previously considered extinct--yet two of these species occurred in higher densities in the unsaturated sediments. Conservation and management efforts along gravel-bed rivers must therefore promote a dynamic flow and sediment regime to create and maintain habitat heterogeneity and ecotone diversity, which support a unique and high biodiversity.

  5. A New Monitoring Method of Individual Particles During Bed Load Transport in a Gravel Bed River.

    NASA Astrophysics Data System (ADS)

    Tremblay, M.; Marquis, G.; Roy, A.; Lamarre, H.

    2009-05-01

    Many particle tracers (passive or active) have been developed to study gravel movement in rivers. It remains difficult however to document resting and moving periods and to know how particles travel from one sedimentation site to another. We have developed a new tracking method using the Hobo Pendant G acceleration Data Logger, to quantitatively describe the motion of individual particles from the initiation of movement, through the displacement and to the rest, in a natural gravel river. The Hobo measures the acceleration in three dimensions at a chosen frequency. Hobo Pendant G Acceleration data logger were inserted into 11 artificial rocks and seeded in Ruisseau Béard, a small gravel river in the Yamaska drainage basin (Québec). The hydraulics, particle sizes and bed characteristics of this site are well known. Controlled tests have been performed before the field experiment to understand the response of the instrument. The results allow us to develop an algorithm which classifies the signal into periods of rest and motion. The algorithm can also differentiate the type of motion: vibration, rolling and sliding of the particles. The data allow us to describe the time of movement, the path length and the velocity of the particles. The comparison of the movement and rest periods to the hydraulic conditions (discharge, shear stress, stream power) established the movement threshold and response times. Relations with bed roughness and morphology were also established. Finally, the development of a 2-dimension model helps visualizing the angular variation motion and a 3D model allows the reconstitution of the particle trajectories on the bed. This method offers great potential to track individual particles and to study bedload transport in rivers. This first attempt needs to be further improved especially to retire the degree of precision of the movement detection. The method should also be tested with frequencies higher than one minute, with more particles of

  6. Quantifying flood duration controls on chute cutoff formation in a wandering gravel-bed river

    NASA Astrophysics Data System (ADS)

    Sawyer, A.; Wilcox, A. C.

    2014-12-01

    Chute cutoffs, which occur when a bypass or "chute" channel incises across a point or braid bar, distribute water and sediment, regulate sinuosity, and create off-channel habitat in wandering gravel-bed rivers. Cutoffs have been hypothesized to occur by progressive migration preparing a bend for cutoff, after which overbank flow events provide a trigger to excavate new channels. This trigger may depend on the magnitude and duration of floods and their associated sediment fluxes. Here we investigated how overbank flow duration impacts cutoff formation in a wandering gravel-bed river. To explore this, we applied a two-dimensional hydrodynamic model to a recently reconstructed reach of the Clark Fork River in western Montana that experienced chute cutoffs during a long-duration flood event in 2011. Hydrographs exceeding bankfull and with varying durations were simulated to constrain the role of overbank flow duration on erosional work in chute cutoff channels. For each magnitude-frequency-duration combination, cumulative excess shear stress (i.e., above the threshold of sediment mobilization) was quantified for in-channel and overbank areas. Locations of shear stress divergence associated with morphological change were identified along chute pathways. Preliminary results suggest that overbank areas containing concentrated flowpaths such as swales follow cumulative excess shear stress curve patterns similar to in-channel areas. This work describes a dynamic system characteristic of wandering gravel-bed rivers in the Pacific Northwest, and has implications for understanding morphodynamic evolution, river restoration targeting off-channel habitat for fish, and geomorphic flow regime management in regulated rivers.

  7. Self-potential investigations of a gravel bar in a restored river corridor

    USGS Publications Warehouse

    Linde, N.; Doetsch, J.; Jougnot, D.; Genoni, O.; Durst, Y.; Minsley, B.J.; Vogt, T.; Pasquale, N.; Luster, J.

    2011-01-01

    Self-potentials (SP) are sensitive to water fluxes and concentration gradients in both saturated and unsaturated geological media, but quantitative interpretations of SP field data may often be hindered by the superposition of different source contributions and time-varying electrode potentials. Self-potential mapping and close to two months of SP monitoring on a gravel bar were performed to investigate the origins of SP signals at a restored river section of the Thur River in northeastern Switzerland. The SP mapping and subsequent inversion of the data indicate that the SP sources are mainly located in the upper few meters in regions of soil cover rather than bare gravel. Wavelet analyses of the time-series indicate a strong, but non-linear influence of water table and water content variations, as well as rainfall intensity on the recorded SP signals. Modeling of the SP response with respect to an increase in the water table elevation and precipitation indicate that the distribution of soil properties in the vadose zone has a very strong influence. We conclude that the observed SP responses on the gravel bar are more complicated than previously proposed semi-empiric relationships between SP signals and hydraulic head or the thickness of the vadose zone. We suggest that future SP monitoring in restored river corridors should either focus on quantifying vadose zone processes by installing vertical profiles of closely spaced SP electrodes or by installing the electrodes within the river to avoid signals arising from vadose zone processes and time-varying electrochemical conditions in the vicinity of the electrodes. ?? 2011 Author(s).

  8. Storage and residence time of suspended sediment in gravel bars of Difficult Run, VA

    NASA Astrophysics Data System (ADS)

    George, J.; Benthem, A.; Pizzuto, J. E.; Skalak, K.

    2016-12-01

    Reducing the export of suspended sediment is an important consideration for restoring water quality to the Chesapeake Bay, but sediment budgets for in-channel landforms are poorly constrained. We quantified fine (< 2 mm) sediment storage and residence times for gravel bars at two reaches along Difficult Run, a 5th order tributary to the Potomac River. Eight gravel bars were mapped in a 150m headwater reach at Miller Heights (bankfull width 11m; total bar volume 114 m3) and 6 gravel bars were mapped in a 160m reach downstream near Leesburg Pike (bankfull width 19m; total bar volume 210 m3). Grain size analyses of surface and subsurface samples from 2 bars at each reach indicate an average suspended sediment content of 55%, suggesting a total volume of suspended sediment stored in the mapped bars to be 178 m3, or 283000 kg, comprising 5% of the average annual suspended sediment load of the two study reaches. Estimates of the annual bedload flux at Miller Heights based on stream gaging records and the Wilcock-Crowe bedload transport equation imply that the bars are entirely reworked at least annually. Scour chains installed in 2 bars at each site (a total of 50 chains) recorded scour and fill events during the winter and spring of 2016. These data indicate that 38% of the total volume of the bars is exchanged per year, for a residence time of 2.6 ± 1.2 years, a value we interpret as the residence time of suspended sediment stored in the bars. These results are supported by mapping of topographic changes derived from structure-from-motion analyses of digital aerial imagery. Storage in alluvial bars therefore represents a significant component of the suspended sediment budget of mid-Atlantic streams.

  9. Morphodynamic Modeling of Gravel Bed Rivers: a Step-Length Based Approach

    NASA Astrophysics Data System (ADS)

    Kasprak, A.; Wheaton, J. M.

    2011-12-01

    Quantifying gravel bed river morphodynamics over decadal to centennial timescales is integral to making informed stream management and restoration decisions. Factors such as land use and climate shifts over such timescales may drastically alter stream evolution - with major implications for in-channel and riparian habitat. Due to these longer-term changes, field-based studies are often unable to fully capture morphologic shifts. Scenario-based morphodynamic modeling has emerged as a viable means of quantifying gravel bed river evolution, yet current models fall short with regard to their ability to predict changes in stream morphology over the timescales in question and with adequate spatial resolution, a problem due largely to the computational overhead they require. While the computing power required to quantify sediment transport has hindered previous modeling efforts, field-based research suggests a potential improvement: sediment is often mobilized downstream with characteristic step-lengths. Here we introduce a morphodynamic model which drives sediment transport using a step-length based approach, negating the need for frequent recalculation of sediment dynamics in the flow, and correspondingly reducing computational overhead. Upon application of this model to the River Feshie (UK), we observe that it accurately reproduces many bed morphologies observed during annual RTK-GPS and terrestrial lidar surveys. Subsequently, we utilize this new model to quantify morphologic outcomes under various discharge and sediment regimes. By utilizing simple step-length based sediment transport distributions, the formation and preservation of bed morphologies can be accurately predicted with less computational overhead than offered in previous morphodynamic modeling efforts. The knowledge gained from scenario-based modeling using this new scheme may aid in the management and restoration of gravel bed streams under shifting discharge and sediment regimes.

  10. The generation of coherent flow structures in a gravel bed river

    NASA Astrophysics Data System (ADS)

    Hardy, R. J.; Best, J.; Parsons, D.; Christensen, K.

    2010-12-01

    Turbulence in rivers is not a simple random field: visualisation and multipoint measurements show it is possible to decompose complex, multi-scaled, quasi-random flow fields into elementary organized structures which posses both spatial and temporal coherence termed either eddies or coherent flow structures (CFS). Quantifying the kinematic (size, scaling, shape, vorticity and energy) and dynamic (origin, stability, growth, genesis into new forms and contribution to averages) characteristics of CFS in gravel-bed rivers are central to improving our understanding of turbulent flow, and the contribution of CFS to shear stress, and hence sediment transport. Much of our uncertainty in understanding CFS over gravel-beds stems from two fundamental shortcomings: i) previous studies have used Reynolds decomposition of Eulerian time series to quantitatively determine processes, which may be interpolated to examine the whole flow field, rather than studying the complete instantaneous flow field; and ii) whole flow field visualization provides a qualitative understanding, but very little quantitative information. Here, we demonstrate a new experimental methodology to quantify simultaneously both the kinematic and dynamic characteristics of coherent flow structures based upon combined planar Laser Induced Fluorescence and Particle Imaging Velocimetry (pLIF-PIV) over a gravel surface for a range of Reynolds numbers. Snapshot POD is applied to the PIV results to determine the initiation of the structures. Initial results agree with the model of Falco (1991) that divides the outer flow into two distinct types of motion; large-scale motions, which are clearly being detected by the pLIF, and smaller ‘typical’ eddies, which the PIV is detecting within these large-scale structures. These results also conform with classical boundary layer hydraulics, where the dominant motions of flow have been shown to be the large-scale regions of momentum deficit that are elongated in the

  11. Self-potential investigations of a gravel bar in a restored river corridor

    USGS Publications Warehouse

    Linde, N.; Doetsch, J.; Jougnot, D.; Genoni, O.; Durst, Y.; Minsley, Burke J.; Vogt, T.; Pasquale, N.; Luster, J.

    2011-01-01

     Self-potentials (SP) are sensitive to water fluxes and concentration gradients in both saturated and unsaturated geological media, but quantitative interpretations of SP field data may often be hindered by the superposition of different source contributions and time-varying electrode potentials. Self-potential mapping and close to two months of SP monitoring on a gravel bar were performed to investigate the origins of SP signals at a restored river section of the Thur River in northeastern Switzerland. The SP mapping and subsequent inversion of the data indicate that the SP sources are mainly located in the upper few meters in regions of soil cover rather than bare gravel. Wavelet analyses of the time-series indicate a strong, but non-linear influence of water table and water content variations, as well as rainfall intensity on the recorded SP signals. Modeling of the SP response with respect to an increase in the water table elevation and precipitation indicate that the distribution of soil properties in the vadose zone has a very strong influence. We conclude that the observed SP responses on the gravel bar are more complicated than previously proposed semi-empiric relationships between SP signals and hydraulic head or the thickness of the vadose zone. We suggest that future SP monitoring in restored river corridors should either focus on quantifying vadose zone processes by installing vertical profiles of closely spaced SP electrodes or by installing the electrodes within the river to avoid signals arising from vadose zone processes and time-varying electrochemical conditions in the vicinity of the electrodes.

  12. Enhanced removal of Exxon Valdez spilled oil Alaskan gravel by a microbial surfactant

    SciTech Connect

    Harvey, S.; Elashvili, I.; Valdes, J.J.; Kamely, D.; Chakrabarty, A.M. )

    1990-03-01

    Remediation efforts for the oil spill from the Exxon Valdez tanker in Alaska have focused on the use of pressurized water at high temperature to remove oil from the beaches. We have tested a biological surfactant from Pseudomonas aeruginosa for its ability to remove oil from contaminated Alaskan gravel samples under various conditions, including concentration of the surfactant, time of contact, temperature of the wash, and presence or absence of xanthan gum. The results demonstrate the ability of the microbial surfactant to release oil to a significantly greater extent (2 to 3 times) than water alone, particularly at temperatures of 30{degree}C and above.

  13. Enhanced removal of Exxon Valdez spilled oil from Alaskan gravel by a microbial surfactant.

    PubMed

    Harvey, S; Elashvili, I; Valdes, J J; Kamely, D; Chakrabarty, A M

    1990-03-01

    Remediation efforts for the oil spill from the Exxon Valdez tanker in Alaska have focused on the use of pressurized water at high temperature to remove oil from the beaches. We have tested a biological surfactant from Pseudomonas aeruginosa for its ability to remove oil from contaminated Alaskan gravel samples under various conditions, including concentration of the surfactant, time of contact, temperature of the wash, and presence or absence of xanthan gum. The results demonstrate the ability of the microbial surfactant to release oil to a significantly greater extent (2 to 3 times) than water alone, particularly at temperatures of 30 degrees C and above.

  14. Infiltration of silt-sized sediment in a gravel-bed channel

    NASA Astrophysics Data System (ADS)

    Herrero, Albert; Berni, Céline; Camenen, Benoit; Thollet, Fabien

    2014-05-01

    In mountain and piedmont hydro-systems, gravel-bed rivers often transport large amounts of fine (silt-sized) sediments. The dynamics of such a sediment mixture is usually described as a simple superposition of two independent modes of sediment transport: a suspension of fine sediments over a bed load of gravels. However, the interaction between the two classes of sediment may be strong. This study is mainly focused on one of the aspects of this interaction, which is the development of a clogged layer through the infiltration of fine sediment into a coarser bed. Clogging affects the spawning process of many fluvial fish species and has different socio-economic consequences concerning to water supply and river dam management operations. Previous studies highlight the influence of flow velocity and fine sediment concentration on the total amount of fine sediments infiltrated within the gravel bed and their depth distribution. Moreover, the ratio of fine to coarse sediment size has proved to be determinant concerning to the mechanism of infiltration and the formation or not of a sealing layer at the surface of the channel bed that prevents from deeper infiltration of fine material. This study is based on laboratory experiments performed in a 18-meter long and 1-meter wide channel. It focused on the analysis of the infiltration processes of silt-sized suspended sediment within a gravel channel bed (mean diameters of 30µm and 8mm, respectively). Such experiment with a ratio over 200 between the two grain sizes is poorly described in the literature. The influence of flow velocity and suspended sediment concentration on the amount of sediment infiltrated is analysed. Determination of velocity profiles is carried out in order to quantify bottom shear stress and its effect on the infiltration process. On the other hand, results on depth distribution of the infiltrated sediment are provided and interpreted, discussing the mechanisms of infiltration and the physical processes

  15. Stochastic Variations in Transport Capacity and its Role in 'Long- Runout' Gravel Progradation in Alluvial Basins

    NASA Astrophysics Data System (ADS)

    Engelder, T. M.; Pelletier, J. D.

    2008-12-01

    Sediment transport in gravel-bed rivers requires a critical shear stress. Several recent studies have used the critical shear stress criterion, together with measurements of median grain size and channel depth in ancient fluvial deposits, to infer the paleoslopes of alluvial basins in the western United States. In some applications of this method, inferred paleoslopes are sufficiently large that tectonic tilting must be invoked in order for the sediments to have been transported to their present locations. In this paper, we evaluate the robustness of the paleoslope-estimation method within the context of a coupled numerical model for the postorogenic topographic decay of a mountain belt coupled to a coarse-grained foreland sedimentary basin. In the model, critical slopes for entrainment are varied stochastically in time (to represent fluctuations in flow depth and local deviations from an equilibrium channel geometry) with a lognormal distribution characterized by a constant mean and variance equal to the values measured in a large dataset of gravel bed rivers in North America. The model shows that when critical slope values vary stochastically, foreland basin sediments can persistently prograde at slopes far below the minimum value predicted by paleoslope-estimation theory. As such, the model suggests that coarse-grained 'long-runout' gravels do not necessarily require steep slopes to form, especially in hydroclimatic regions characterized by flashy discharges, climatic changes, local deviations from channel equilibrium, and in cases when deposition occurs over long spans of geologic time. The model also suggests that postorogenic topographic decay is characterized by three distinct phases: an initial phase characterized by knickpoint retreat in the mountain belt and proximal deposition in the adjacent foreland basin (lasting ~5 Myr), a second phase in which erosion and deposition balance to maintain a constant basin aspect ratio (~5 to 10 Myr) and a third phase

  16. Hyporheic Exchange in Gravel-Bed Rivers with Pool-Riffle Morphology: A 3D Model

    NASA Astrophysics Data System (ADS)

    Tonina, D.; Buffington, J. M.

    2004-12-01

    The hyporheic zone is a saturated band of sediment that surrounds river flow and forms a linkage between the river and the aquifer. It is a rich ecotone where benthic, hyporheic, and groundwater species temporarily or permanently reside. Head gradients along the streambed draw river water into the hyporheic zone and expel pore water into the stream. This process, known as hyporheic exchange, is important for delivering nutrients, oxygen and other solutes to the sediment, and for washing away waste products to support this ecotone. It is an essential component of the carbon and nitrogen cycles, and it controls in-stream contaminant transport. Although hyporheic exchange has been studied in sand-bed rivers with two-dimensional dune morphology, few studies have been conducted for gravel-bed rivers with three-dimensional pool-riffle geometry. The hyporheic zone of gravel-bed rivers is particularly important for salmonids, many of which are currently at risk world wide. Salmon and trout lay their eggs within the hyporheic zone for incubation. After hatching, the alevins live in the gravel before emerging into the stream. The upwelling and downwelling hyporheic fluxes are intense in these streams due to the highly permeable sediment and strong head variations forced by shallow flow over high-amplitude bed forms. Moreover, gravel-bed rivers show a wide range of flow regimes that change seasonally and have strong effects on hyporheic exchange. To study this exchange, we used four sets of pool-riffle geometries in twelve recirculating flume experiments. We kept a constant bed-form wavelength, but changed the bed-form amplitude and imposed three discharges, covering a wide range of hydraulic and geometric characteristics. Hyporheic exchange was predicted from a three-dimensional model based on bedform-induced pumping transport, where the boundary head profile is the pressure head distribution at the sediment interface, measured with an array of mini-piezometers buried within

  17. Field study of gravel admix, vegetation, and soil water interactions: Protective Barrier Program Status Reprt - FY 1989

    SciTech Connect

    Waugh, W.J.; Thiede, M.E.; Kemp, C.J.; Cadwell, L.L. Link, S.O.

    1990-08-01

    Pacific Northwest Laboratory (PNL) and Westinghouse Hanford Company (Westinghouse Hanford) are collaborating on a field study of the effects of gravel admixtures on plant growth and soil water storage in protective barriers. Protective barriers are engineered earthern covers designed to prevent water, plants, and animals from contacting buried waste and transporting contaminants to groundwater or the land surface. Some of the proposed designs include gravel admixtures or gravel mulches on the barrier surface to control soil loss by wind and runoff. The purpose of this study is to measure, in a field setting, the influence of surface gravel additions on soil water storage and plant cover. The study plots are located northwest of the Yakima Gate in the McGee Ranch old field. Here we report the status of work completed in FY 1989 on the creation of a data management system, a test of water application uniformity, field calibration of neutron moisture gages, and an analysis of the response of plants to various combinations of gravel admixtures and increased rainfall. 23 refs., 11 figs., 6 tabs.

  18. An innovative technique for damage by-pass in gravel packed completions using tip screen-out fracture prepacks

    SciTech Connect

    Montagna, J.N.; Saucier, R.J.; Kelly, P.

    1995-12-31

    An innovative completion technique is being used in wells that require sand control to help eliminate high skins and increase pay, or effective kh, and thus improve well productivity. The success of this technique lies in concentrating high conductivity proppants in the near-wellbore region. This is accomplished by creating and propping a properly designed, length limited, hydraulically-induced fracture in conjunction with an annular water gravel pack. The result is a highly conductive flow path from virgin formation, through the near-wellbore damaged zone, and into the wellbore that also controls formation sand. The limited fracture is designed with the intent of preserving the integrity of the near well gravel pack since this aspect is critical to realizing the full benefits of the fracture. Industry data indicates that optimum gravel packing is achieved with a brine proppant carrier. In some cases, the entire operation (limited fracture and gravel pack) may be completed with brine. However, in other cases, as discussed here, the high leak-off associated with brine is reduced by a product developed to overcome the excessive fluid leak-off. Brine following this material provides the carrier medium for proppant placement in the fracture and for the gravel pack. The process is described and examples of field applications and results will be presented.

  19. Impact of Sand and Gravel Mining on Groundwater Resources in La Bassée Alluvial Plain, France.

    NASA Astrophysics Data System (ADS)

    Jost, A.; Wang, S.; Labarthe, B.; Flipo, N.

    2016-12-01

    The alluvial plain of La Bassée, in the middle reach of the Seine River (France), is both of environmental importance as a major wetland and at the centre of strategic issues regarding inland waterways transport, flood prevention, water and granular resources. The sand and gravel mining industry has been productive for more than five decades over the area and contributes to 40% of the regional production of natural aggregates. Former and active gravel pits cover about 10% of the areal extent of the plain. Gravel pit lakes interact with groundwater from the surrounding alluvial aquifer and the underlying chalk aquifer. By exposing groundwater to the atmosphere, they can act as a sink/source for the groundwater system through atmospheric exchange. We develop a model-based approach using the EauDyssée platform for determining the impact of such lakes on groundwater resources in terms of quantity and how they affect groundwater level and flow paths. Over the alluvial plain area of La Bassée a local model is built, which takes its hydrodynamic parameters from an inverse calibration procedure and its boundary conditions from a coarser regional model run on the whole Seine basin. To efficiently simulate lake-groundwater exchange, the modelling platform was extended by a lake module. The effet of gravel excavation is investigated by quantifying the gravel pit lakes water budget and by simulating groundwater transient response over almost two decades.

  20. Pliocene terrace gravels of the ancestral Yukon River near Circle, Alaska: Palynology, paleobotany, paleoenvironmental reconstruction and regional correlation

    USGS Publications Warehouse

    Ager, T.A.; Matthews, J.V.; Yeend, W.

    1994-01-01

    Gravels deposited by the ancestral Yukon River are preserved in terrace remnants on the margins of the Yukon River valley near the village of Circle in east-central Alaska. Plant fossils recovered from sandy silt lenses within these gravels include cones and needles of Picea and Larix and a variety of seeds. Seed types include several taxa which no longer grow in Alaska, such as Epipremnum, Prunus and Weigela. Pollen types recovered from these deposits represent tree and shrub taxa that grow in interior Alaska today, such as Picea, Larix, Betula and Alnus, as well as several taxa that no longer grow in interior Alaska today, such as Pinus, Tsuga, Abies and Corylus. Pollen of herb taxa identified include Gramineae, Cyperaceae, Caryophyllaceae, Compositae, Polemonium and Epilobium. The fossil flora from the gravels near Circle are similar and probably age-equivalent to the flora recovered from the Nenana Gravel in the Alaska Range 250 km to the south. Palynological and tectonic evidence summarized in this paper now suggests that the Nenana Gravel was deposited during the early and middle Pliocene. The presence of plant fossils of Tsuga, Abies, Pinus, Weigela and Prunus suggests that the mean annual temperature (MAT) of eastern interior Alaska during the early and middle Pliocene was perhaps 7-9??C warmer and less continental than today's MAT of -6.4??C. ?? 1994.

  1. Data report for the geologic and scenic quality evaluation of selected sand and gravel sites on the Wind River Indian Reservation, Wyoming

    USGS Publications Warehouse

    Langer, William H.; Van Gosen, Bradley S.; Arbogast, Belinda; Lindsey, David A.

    2011-01-01

    In April 2005, the U.S. Geological Survey (USGS) conducted field studies on the Wind River Indian Reservation, Wyoming, to inventory and evaluate sand and gravel deposits underlying river terraces on tribal lands along the Wind River. This report contains the results for 12 sites of sand and gravel deposits evaluated for their potential use as aggregate in Portland cement concrete, asphalt, and base course. The report provides the results of: * The USGS geologic studies and engineering tests. * A conclusion and recommendation for the best use of sand and gravel materials. * Calculations of available sand and gravel materials. * A scenic quality landscape inventory and evaluation.

  2. Gravel pit lake ecosystems reduce nitrate and phosphate concentrations in the outflowing groundwater.

    PubMed

    Weilhartner, Andreas; Muellegger, Christian; Kainz, Martin; Mathieu, Francine; Hofmann, Thilo; Battin, Tom J

    2012-03-15

    Gravel excavation often bears conflicts with the use of drinking water as under-water-table mining can directly impact groundwater quality downstream of the open gravel pit lake due to exposure of the groundwater aquifer to the atmosphere and to human activities. To assess this potential impact of GPLs on groundwater, we assessed the mass balance for nitrate (NO(3)) and phosphate (PO(4)) and whole-ecosystem metabolism of five post-excavation GPLs in Austria. GPLs differed in both age and residence time of lake water. We found that GPLs significantly reduced the concentration of NO(3) and PO(4) as groundwater passes through the lake ecosystem, which in most cases acted as a net sink for these nutrients. Groundwater-derived nutrients enhanced both epilithic and pelagic net primary production in the GPLs, which ultimately leads to biomass accrual. Our data also suggest that this biomass accrual may induce, at least in part, clogging of the GPLs and their successive hydrodynamic isolation from the adjacent groundwater. Despite continuous biomass build-up and elevated concentrations of dissolved organic carbon (DOC) in the lake water compared to the inflowing groundwater, DOC export into the outflowing groundwater remained low. Our data suggest that GPLs could contribute to groundwater amelioration where agricultural land use increases nutrient concentrations in the groundwater given a proper management of these man-made ecosystems.

  3. Large submarine sand waves and gravel lag substrates on Georges Bank off Atlantic Canada

    USGS Publications Warehouse

    Todd, B.J.; Valentine, Page C.; Harris, Peter T; Baker, E.K.

    2012-01-01

    Georges Bank is a large, shallow, continental shelf feature offshore of New England and Atlantic Canada. The bank is mantled with a veneer of glacial debris transported during the late Pleistocene from continental areas lying to the north. These sediments were reworked by marine processes during postglacial sea-level transgression and continue to be modified by the modern oceanic regime. The surficial geology of the Canadian portion of the bank is a widespread gravel lag overlain in places by well sorted sand occurring as bedforms. The most widespread bedforms are large, mobile, asymmetrical sand waves up to 19 m in height formed through sediment transport by strong tidal-driven and possibly storm-driven currents. Well-defined curvilinear bedform crests up to 15 km long form a complex bifurcating pattern having an overall southwest–northeast strike, which is normal to the direction of the major axis of the semidiurnal tidal current ellipse. Minor fields of immobile, symmetrical sand waves are situated in bathymetric lows. Rare mobile, asymmetrical barchan dunes are lying on the gravel lag in areas of low sand supply. On Georges Bank, the management of resources and habitats requires an understanding of the distribution of substrate types, their surface dynamics and susceptibility to movement, and their associated fauna.

  4. The relationship between particle strength and particle breakage in loaded gravels

    NASA Astrophysics Data System (ADS)

    Fityus, Stephen; Simmons, John

    2017-06-01

    The particle breakage behaviour of coarse grains during shearing of a gravelly granular assemblage changes in accordance with the magnitude of the confining stress acting on the assemblage. The transition from particle rearrangement and sliding to particle breakage is studied for two gravelly materials subjected to a wide range of compressive and shear stresses (10kPa to 3.5MPa). The tested materials are a gravel fraction derived from crushed sedimentary sandstones and shales, and a gravel derived from a crushed rhyodacitic volcanic. At low confining stresses, breakage due to compression and shear are both small, with only some fine fragments produced. Confining stress increase results in a stage being reached where particle damage starts to increase greatly, under both compressive and shearing loads. The results indicate that, as stresses become very large, the particle breakage due to compression continues to increase, but the breakage due to shearing under the same vertical stress actually decreases. This is attributed to the attainment of a fabric which, through extreme damage during compression, allows subsequent shearing with reduced additional particle damage.

  5. Passive acoustic monitoring of bed load discharge in a large gravel bed river

    NASA Astrophysics Data System (ADS)

    Geay, T.; Belleudy, P.; Gervaise, C.; Habersack, H.; Aigner, J.; Kreisler, A.; Seitz, H.; Laronne, J. B.

    2017-02-01

    Surrogate technologies to monitor bed load discharge have been developed to supplement and ultimately take over traditional direct methods. Our research deals with passive acoustic monitoring of bed load flux using a hydrophone continuously deployed near a river bed. This passive acoustic technology senses any acoustic waves propagated in the river environment and particularly the sound due to interparticle collisions emitted during bed load movement. A data set has been acquired in the large Alpine gravel-bedded Drau River. Analysis of the short-term frequency response of acoustic signals allows us to determine the origin of recorded noises and to consider their frequency variations. Results are compared with ancillary field data of water depth and bed load transport inferred from the signals of a geophone array. Hydrophone and geophone signals are well correlated. Thanks to the large network of deployed geophones, analysis of the spatial resolution of hydrophone measurements shows that the sensor is sensitive to bed load motion not only locally but over distances of 5-10 m (10-20% of river width). Our results are promising in terms of the potential use of hydrophones for monitoring bed load transport in large gravel bed rivers: acoustic signals represent a large river bed area, rather than being local; hydrophones can be installed in large floods; they can be deployed at a low cost and provide continuous monitoring at high temporal resolution.

  6. Hydrology of sand-and-gravel aquifer in central and southern Escambia County, Florida

    USGS Publications Warehouse

    Trapp, Henry

    1975-01-01

    The sand-and-gravel aquifer is the only fresh-water aquifer in the Pensacola area. Problems related to development of the aquifer include maximum safe yield, local contamination, local salt-water intrusion, corrosiveness of the water, areas of high iron concentration, and increasing nitrate concentration. The city of Pensacola is seeking hydrologic information, including water-quality data, to plan for future expansion of the water-supply system. This report summarizes the third year's findings of a 6-year study of the sand-and-gravel aquifer. Although the thickness of the aquifer locally exceeds 1,000 feet (300 metres) most of the clean sand layers are no more than 450 feet (140 metres) below land surface. The highest head is at the north edge of the area; the head is drawn down below sea level in areas of heavy pumping. Ground water moves southward from the northern half of the county to be intercepted near Cantonment. Virtually all ground water discharged south of Cantonment derives from local precipitation. The report contains maps showing concentrations of carbon dioxide, nitrate, and iron in water from the aquifer, potentiometric maps, geohydrologic sections, and lithologic and radioactive logs of test holes.

  7. Lithology of gravel deposits of the Front Range urban corridor, Colorado: data and multivariate statistical analysis

    USGS Publications Warehouse

    Lindsey, David A.

    2001-01-01

    Pebble count data from Quaternary gravel deposits north of Denver, Colo., were analyzed by multivariate statistical methods to identify lithologic factors that might affect aggregate quality. The pebble count data used in this analysis were taken from the map by Colton and Fitch (1974) and are supplemented by data reported by the Front Range Infrastructure Resources Project. This report provides data tables and results of the statistical analysis. The multivariate statistical analysis used here consists of log-contrast principal components analysis (method of Reyment and Savazzi, 1999) followed by rotation of principal components and factor interpretation. Three lithologic factors that might affect aggregate quality were identified: 1) granite and gneiss versus pegmatite, 2) quartz + quartzite versus total volcanic rocks, and 3) total sedimentary rocks (mainly sandstone) versus granite. Factor 1 (grain size of igneous and metamorphic rocks) may represent destruction during weathering and transport or varying proportions of rocks in source areas. Factor 2 (resistant source rocks) represents the dispersion shadow of metaquartzite detritus, perhaps enhanced by resistance of quartz and quartzite during weathering and transport. Factor 3 (proximity to sandstone source) represents dilution of gravel by soft sedimentary rocks (mainly sandstone), which are exposed mainly in hogbacks near the mountain front. Factor 1 probably does not affect aggregate quality. Factor 2 would be expected to enhance aggregate quality as measured by the Los Angeles degradation test. Factor 3 may diminish aggregate quality.

  8. Late Tertiary floral assemblage from upland gravel deposits of the southern Maryland Coastal Plain

    NASA Astrophysics Data System (ADS)

    McCartan, Lucy; Tiffney, Bruce H.; Wolfe, Jack A.; Ager, Thomas A.; Wing, Scott L.; Sirkin, Leslie A.; Ward, Lauck W.; Brooks, James

    1990-04-01

    A diverse flora has been discovered in a dark clay lens in upland gravel in southern Maryland near Brandywine. More than 49 taxa have been identified in the assemblage, which includes leaves, seeds, fruits, pollen, and a Taxodium (bald cypress) trunk. The vegetation is dominated by deciduous trees and vines. Four taxa are now absent from North America but survive elsewhere; one is extinct. A late Miocene age and warm-temperate climate are inferred from the flora. The clay lens probably represents a cutoff distributary in the extensive braided stream system that covered the area and is unique in Maryland. Similar dark clays have been described from Miocene sands and gravels in New Jersey. The Brandywine flora is the first direct evidence of the Miocene age of part of the fluvial upland deposits of Maryland. On the basis of the age inferred from the flora, the Brandywine deposit is correlated with the St. Marys Formation or the Eastover Formation, which are upper Miocene shelly marine units south and southeast of Brandywine.

  9. The timing of scour and fill in a gravel-bedded river measured with buried accelerometers

    USGS Publications Warehouse

    Gendaszek, Andrew S.; Magirl, Christopher S.; Czuba, Christiana R.; Konrad, Christopher P.

    2013-01-01

    A device that measures the timing of streambed scour and the duration of sediment mobilization at specific depths of a streambed was developed using data-logging accelerometers placed within the gravel substrate of the Cedar River, Washington, USA. Each accelerometer recorded its orientation every 20 min and remained stable until the surrounding gravel matrix mobilized as sediment was transported downstream and scour reached the level of the accelerometer. The accelerometer scour monitors were deployed at 26 locations in salmon-spawning habitat during the 2010–2011 flood season to record when the streambed was scoured to the depth of typical egg-pocket deposition. Scour was recorded at one location during a moderate high-flow event (65 m3/s; 1.25–1.5-year recurrence interval) and at 17 locations during a larger high-flow event (159 m3/s; 7-year recurrence interval). Accelerometer scour monitors recorded periods of intermittent sediment mobilization and stability within a high-flow event providing insight into the duration of scour. Most scour was recorded during the rising limb and at the peak of a flood hydrograph, though some scour occurred during sustained high flows following the peak of the flood hydrograph.

  10. Recirculating gravel filters: high-performance treatment at low cost for two small communities.

    PubMed

    Newton, C; Wilson, J P

    2008-01-01

    Wastewater from small communities often has a greater environmental impact than conventional on-site treatment systems can mitigate, yet the flow rate is too low to achieve economies of scale with municipal treatment processes. As a result, the cost of wastewater treatment is often beyond the financial means of the community, in terms of capital costs and annual operational costs. The recirculating gravel filter (RGF) is an attached-growth treatment process for wastewater from small communities. In the RGF process, pre-settled wastewater is recirculated through a gravel filter bed, while a biofilm on the filter media oxidizes the organic matter and ammonia. Effluent from the RGF process has equivalent or lower concentrations of BOD5, TSS and ammonia nitrogen as effluent from other wastewater treatment processes typically employed in small communities. Two small communities in Washington State, USA, have selected the RGF process for wastewater treatment, due to low operational costs, simplicity of equipment, and high effluent quality. For the two communities, the RGF wastewater treatment facilities were estimated to have somewhat lower construction costs and significantly lower annual operational costs than the alternatives evaluated. Low annual operational expenses are important for wastewater system sustainability in small communities. IWA Publishing 2008.

  11. Stability of nickel-coated sand as gravel-pack material for thermal wells

    SciTech Connect

    Sacuta, A.; Nguyen, D.M.; Kissel, G.A. )

    1988-11-01

    Laboratory flow tests have been carried out to study the stability of various nickel-coated sands under aqueous steam temperature and pH conditions that may exist in thermal recovery operations. Other gravel-pack materials tested include Ottawa sand, sintered bauxite, cement clinker, zirconium oxide, and nickel pellets. A comparison was made between the performances of these materials after exposure to identical thermal and hydrolytic conditions. Test results indicate that nickel-coated sands are highly resistant to dissolution at temperatures as high as 300/sup 0/C (570/sup 0/F) and to solution pH's from 4.75 to 11. Weight losses measured after a 72-hour period were less than 1%. In contrast, weight losses from sintered bauxite, zirconium oxide, and Ottawa sand dissolution tests were 30 to 70 times higher under the same conditions. Cement clinker losses were in the intermediate range under alkaline conditions. API standard crushing and acid-solubility tests for proppants also were performed on nickel-coated sands. These results were favorable in that they exceeded the recommended standards. This study of nickel-coated sand stability and mechanical strength has demonstrated its high potential for application as either a gravel-pack material or proppant in thermal recovery operations.

  12. Flood duration and chute cutoff formation in a wandering gravel-bed river

    NASA Astrophysics Data System (ADS)

    Sawyer, A.; Wilcox, A. C.

    2015-12-01

    Chute cutoffs occur when a bypass or "chute" channel incises across a bar or low floodplain area, re-distributing water and sediment. Cutoffs result from a setup and a triggering event, typically during overbank flow, but the combined effect of magnitude and duration on potential erosion in in-channel and overbank areas is still poorly constrained. Here we investigated how overbank flow duration impacts cutoff formation and spatiotemporal shear stress patterns in a wandering gravel-bed river. We applied a two-dimensional hydraulic model to a recently reconstructed reach of the Clark Fork River in western Montana that experienced chute cutoffs during a long-duration flood in 2011. Hydrographs with increasing durations exceeding overbank were simulated; for each magnitude-duration combination, various metrics were quantified for in-channel and overbank areas separately. We confirm the hypothesized importance of floodplain elevation, vegetation presence, chute-channel inlet entrance location, and high overbank shear stress zones at bend apexes on cutoff occurrence. Floodplain width plays an important role in controlling unit discharge such that overbank areas are more competent in a narrower floodplain conveyance corridor. Duration controls cumulative flow exceeding sediment mobility thresholds, having the largest effect in overbank areas. Side channels at the reconstructed study site act like naturally formed incipient chutes. This work describes a complex floodplain system characteristic of wandering gravel-bed rivers with implications for understanding morphodynamic evolution, river restoration, and flow management in regulated rivers.

  13. Morphology of meandering and braided gravel-bed streams from the Bayanbulak Grassland, Tianshan, China

    NASA Astrophysics Data System (ADS)

    Métivier, F.; Devauchelle, O.; Chauvet, H.; Lajeunesse, E.; Meunier, P.; Blanckaert, K.; Zhang, Z.; Fan, Y.; Liu, Y.; Dong, Z.; Ye, B.

    2015-11-01

    The Bayanbulak Grassland, Tianshan, China is located in an intramountane sedimentary basin where meandering and braided gravel-bed streams coexist under the same climatic and geological settings. We report on measurements of their discharge, width, depth, slope and grain size. Based on this data set, we compare the morphology of individual threads from braided and meandering streams. Both types of threads share statistically indistinguishable regime relations. Their depths and slopes compare well with the threshold theory, but they are wider than predicted by this theory. These findings are reminiscent of previous observations from similar gravel-bed streams. Using the scaling laws of the threshold theory, we detrend our data with respect to discharge to produce a homogeneous statistical ensemble of width, depth and slope measurements. The statistical distributions of these dimensionless quantities are similar for braided and meandering streams. This suggests that a braided river is a collection of intertwined channels, which individually resemble isolated streams. Given the environmental conditions in Bayanbulak, we furthermore hypothesize that bedload transport causes the channels to be wider than predicted by the threshold theory.

  14. Degradation of diesel oil by immobilized Candida tropicalis and biofilm formed on gravels.

    PubMed

    Chandran, Preethy; Das, Nilanjana

    2011-11-01

    The performance of diesel oil degradation by Candida tropicalis immobilized on various conventional matrices (sodium alginate, carboxyl methyl cellulose, chitosan) and biowaste materials (wheat bran, sawdust, peanut hull powder) was investigated using the method of entrapment and physical adsorption. The yeast species immobilized in wheat bran showed enhanced efficiency in degrading diesel oil (98%) compared to free cells culture (80%) over a period of 7 days. Copious amount of exopolysaccharides were also produced in the presence of diesel oil. The biofilm forming ability of C. tropicalis on PVC strips was evaluated using XTT (2,3-bis[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide) reduction assay and monitored by scanning electron microscopy and atomic force microscopy. Yeast biofilm formed on gravels showed 97% degradation of diesel oil over a period of 10 days. The potential use of the biofilms for preparing trickling filters (gravel particles), for attenuating hydrocarbons in oily liquid wastes before their disposal in the open environment is suggested and discussed. This is the first successful attempt for 'artificially' establishing hydrocarbon degrading yeast biofilm on solid substrates.

  15. Soil erosion rates from mixed soil and gravel surfaces in a wind tunnel: A preliminary report

    SciTech Connect

    Ligotke, M.W.

    1988-12-01

    Tests of wind erosion were performed in a controlled-environment wind tunnel to support the development of natural-material protective barriers for long-term isolation of radioactive waste. Barrier performance standards currently being developed for internal and external barrier performance are expected to mandate a surface layer that is resistant to wind erosion. The purpose of this study was to initiate a series of tests to determine suitable soil and gravel mixtures for such a barrier and to test worst-case surface layer conditions under the influence of high wind speeds. Six mixed soil and gravel surfaces were prepared, weathered to represent natural wind-blown desert areas, and subjected to controlled wind erosion forces in a wind tunnel. The applied erosive forces, including surface shear forces, were characterized to provide a means of relating wind tunnel results with actual field conditions. Soil particle losses from the surfaces caused by suspension, saltation, and surface creep were monitored by aerosol sample probes and mass balance measurements. 23 refs., 22 figs., 3 tabs.

  16. Numerical modelling of colmation and decolmation processes for gravel-bed river restoration schemes

    NASA Astrophysics Data System (ADS)

    Stubbs, Alex; Bockelmann-Evans, Bettina; Stoesser, Thorsten

    2017-04-01

    It is well established that man has greatly influenced river sediment loading, which has had a detrimental effect on the aquatic ecosystem, in particular on salmonid spawning in gravel-bed rivers. Successful spawning relies upon a balance between colmation and decolmation processes. Excessive colmation results in juvenile fish being injured through abrasion and adhesion. Without decolmation, juvenile fish trying to emerge from the riverbed, following their incubation period, become trapped. Sediment oxygen demand and intragravel flows can also be influenced by colmation and decolmation resulting in changes in dissolved oxygen levels in the riverbed. Therefore, river restoration schemes often aim to emulate the balance between these processes. However, though conceptually well understood, the physical processes of colmation and decolmation are at best poorly described. This makes the design of restoration schemes challenging and as a result many have had little effect on salmonid spawning whilst some have even been detrimental. It is only with recent advances in technology that it has been possible to understand the complexities of the processes, in particular the influence of microscopic turbulent flows within the near-bed region and within a riverbed's pore matrix. This research aims to further understanding of colmation and decolmation by focusing on the quantification of turbulence close to and within the riverbed facilitating the modelling of these processes. By enhancing the capability of the 2D numerical hydraulic modelling package DIVAST (Depth Integrated Velocities And Solute Transport), this research ultimately aims to improve the design and assessment of gravel-bed river restoration schemes.

  17. Bidirectional reflectance spectrometry of gravel at the Sjökulla test field

    NASA Astrophysics Data System (ADS)

    Peltoniemi, Jouni I.; Piironen, Jukka; Näränen, Jyri; Suomalainen, Juha; Kuittinen, Risto; Markelin, Lauri; Honkavaara, Eija

    The Sjökulla test site is used for testing and calibrating aerial images. The permanent test field is made of four types of gravel (dark gabbro, grey granite, red granite, white limestone) in two sizes (diameters 8-16 mm and 4-8 mm) set in various patterns. The bidirectional reflection properties of the targets together with their temporal changes must be known in order to carry out radiometric and spectral evaluation and calibration. The bidirectional reflectance distribution functions (BRF) of the gravel have been measured several times in the test fields using portable field goniospectrometers belonging Finnish Geodetic Institute (FGI), and once using the European Goniometic Facility (EGO) of the Joint Research Centre (JRC) at Ispra, Italy. Detailed BRFs have been obtained, showing features typical to particulate media, e.g. a small bowl shape, strong backscattering, and smooth wavelength dependence. Temporal range measurements over several years show that the black gabbro and red granite are fairly stable, while the grey granite has changed somewhat over the years and the white limestone has experienced dramatic darkening effects, requiring action to be taken. The measured BRF data have increased the usability of the test field considerably. The results are also useful in the development and validation of scattering models for particulate media. The site has proved to be a good test bench for goniospectrometric instruments, too.

  18. A GIS approach to model sediment reduction susceptibility of mixed sand and gravel beaches.

    PubMed

    Eikaas, Hans S; Hemmingsen, Maree A

    2006-06-01

    The morphological form of mixed sand and gravel beaches is distinct, and the process/response system and complex dynamics of these beaches are not well understood. Process response models developed for pure sand or gravel beaches cannot be directly applied to these beaches. The Canterbury Bight coastline is apparently abundantly supplied with sediments from large rivers and coastal alluvial cliffs, but a large part of this coastline is experiencing long-term erosion. Sediment budget models provide little evidence to suggest sediments are stored within this system. Current sediment budget models inadequately quantify and account for the processes responsible for the patterns of erosion and accretion of this coastline. We outline a new method to extrapolate from laboratory experiments to the field using a geographical information system approach to model sediment reduction susceptibility for the Canterbury Bight. Sediment samples from ten representative sites were tumbled in a concrete mixer for an equivalent distance of 40 km. From the textural mixture and weight loss over 40 km tumbling, we applied regression techniques to generate a predictive equation for Sediment Reduction Susceptibility (SRS). We used Inverse Distance Weighting (IDW) to extrapolate the results from fifty-five sites with data on textural sediment composition to field locations with no data along the Canterbury Bight, creating a continuous sediment reductions susceptibility surface. Isolines of regular SRS intervals were then derived from the continuous surface to create a contour map of sediment reductions susceptibility for the Canterbury Bight. Results highlighted the variability in SRS along this coastline.

  19. Effects of hydraulic roughness on surface textures of gravel-bed rivers

    USGS Publications Warehouse

    Buffington, J.M.; Montgomery, D.R.

    1999-01-01

    Field studies of forest gravel-bed rivers in northwestern Washington and southeastern Alaska demonstrate that bed-surface grain size is responsive to hydraulic roughness caused by bank irregularities, bars, and wood debris. We evaluate textural response by comparing reach-average median grain size (D50) to that predicted from the total bank-full boundary shear stress (??0(bf)), representing a hypothetical reference condition of low hydraulic roughness. For a given ??0(bf), channels with progressively greater hydraulic roughness have systematically finer bed surfaces, presumably due to reduced bed shear stress, resulting in lower channel competence and diminished bed load transport capacity, both of which promote textural fining. In channels with significant hydraulic roughness, observed values of D50 can be up to 90% smaller than those predicted from ??0(bf). We find that wood debris plays an important role at our study sites, not only providing hydraulic roughness but also influencing pool spacing, frequency of textural patches, and the amplitude and wavelength of bank and bar topography and their consequent roughness. Our observations also have biological implications. We find that textural fining due to hydraulic roughness can create usable salmonid spawning gravels in channels that otherwise would be too coarse.

  20. Instream sand and gravel mining: Environmental issues and regulatory process in the United States

    USGS Publications Warehouse

    Meador, M.R.; Layher, A.O.

    1998-01-01

    Sand and gravel are widely used throughout the U.S. construction industry, but their extraction can significantly affect the physical, chemical, and biological characteristics of mined streams. Fisheries biologists often find themselves involved in the complex environmental and regulatory issues related to instream sand and gravel mining. This paper provides an overview of information presented in a symposium held at the 1997 midyear meeting of the Southern Division of the American Fisheries Society in San Antonio, Texas, to discuss environmental issues and regulatory procedures related to instream mining. Conclusions from the symposium suggest that complex physicochemical and biotic responses to disturbance such as channel incision and alteration of riparian vegetation ultimately determine the effects of instream mining. An understanding of geomorphic processes can provide insight into the effects of mining operations on stream function, and multidisciplinary empirical studies are needed to determine the relative effects of mining versus other natural and human-induced stream alterations. Mining regulations often result in a confusing regulatory process complicated, for example, by the role of the U.S. Army Corps of Engineers, which has undergone numerous changes and remains unclear. Dialogue among scientists, miners, and regulators can provide an important first step toward developing a plan that integrates biology and politics to protect aquatic resources.

  1. Capillary pressure-saturation relationships for diluted bitumen and water in gravel

    NASA Astrophysics Data System (ADS)

    Hossain, S. Zubair; Mumford, Kevin G.

    2017-08-01

    Spills of diluted bitumen (dilbit) to rivers by rail or pipeline accidents can have serious long-term impacts on environment and ecology due to the submergence and trapping of oil within the river bed sediment. The extent of this problem is dictated by the amount of immobile oil available for mass transfer into the water flowing through the sediment pores. An understanding of multiphase (oil and water) flow in the sediment, including oil trapping by hysteretic drainage and imbibition, is important for the development of spill response and risk assessment strategies. Therefore, the objective of this study was to measure capillary pressure-saturation (Pc-Sw) relationships for dilbit and water, and air and water in gravel using a custom-made pressure cell. The Pc-Sw relationships obtained using standard procedures in coarse porous media are height-averaged and often require correction. By developing and comparing air-water and dilbit-water Pc-Sw curves, it was found that correction was less important in dilbit-water systems due to the smaller difference in density between the fluids. In both systems, small displacement pressures were needed for the entry of non-wetting fluid in gravel. Approximately 14% of the pore space was occupied by trapped dilbit after imbibition, which can serve as a source of long-term contamination. While air-water data can be scaled to reasonably predict dilbit-water behaviour, it cannot be used to determine the trapped amount.

  2. Bedload transport rates estimated in two gravel bed streams from NW Spain

    NASA Astrophysics Data System (ADS)

    Vázquez-Tarrío, D.; Menéndez-Duarte, R.; Crespo, J.; Fernández, M.

    2012-04-01

    The rivers located in the northern side of Cantabrian Mountain Range (a mountain range which runs parallel to North-western Spanish coast) drain to the Gulf of Biscay, saving a difference of height of roughly 2,000 m in a short path. The climate is Atlantic, with annual rainfall averages around 1,100 mm. The hydrological regime of the main channel is pluvial, with maximum winter discharges and a relatively regular water discharge along the whole year. These facts give place to rivers with a high gradient and with an important contribution of coarse bedload transport to its sedimentary dynamics. In the present work, bedload transport rates were estimated in two gravel bed streams through the use of tracer stones. These two gravel bed streams are a part of the drainage network of Narcea River basin. Narcea River drainage basin has got a catchment surface of 1,800 Km2. Lithology of the basin comprises a diversity of Paleozoic sedimentary rocks (mainly siliciclastic lithologies: quartzarenites, shales and slates) and the vegetation cover shows an alternation of bush areas (mainly heather), beech and oak forests and pastures. An important extension of the basin is represented by headwater channels, with highly-coarse bed sediment, very irregular hydrologic regimes and the occurrence of periodic debris-flow like mass movements. By its side, higher order channels are mainly alluvial reaches with cobble and gravel beds. These reaches develop floodplains, generally with little areal extension and limited spatial continuity (except in the lower parts of the basin). In this work, two gravel bed streams from this basin were selected for estimating bedload transport rates, the Pigüeña river and the Coto river. The both are tributaries of the main Narcea river. Bedload transport rates were estimated through the use of tracer stones. This technique consists on feeding channel bed with tagged stones and measuring its travel distances after flood events capable of moving bed

  3. Response of alternate bar topography to variation in sediment supply in gravel-bedded rivers

    NASA Astrophysics Data System (ADS)

    Venditti, J. G.; Minear, J. T.; Nelson, P. A.; Wooster, J.; Dietrich, W. E.

    2006-12-01

    One of the oft stated goals of stream restoration of channels downstream of dams is the restoration of geomorphic process. Reactivation of geomorphic process in these channels, which are commonly incised with heavily armored river beds, requires replacing the upstream coarse sediment supply in some form. Gravel augmentation projects are often designed with the explicit intent of forming or reactivating channel bars as a means to restoring geomorphic processes, yet our understanding of how channel bars respond to variations in sediment supply is incomplete. As part of two linked laboratory experiments looking at gravel augmentation practices, we examined the conditions under which alternate bars form and how they respond to changes in sediment supply. The first set of experiments were conducted in a 28 m long and 0.86 m wide flume channel using a constant discharge and a unimodal model gravel mix (ranging from 0.8 to 11 mm). The second set of experiments were conducted at a much larger scale in a 55 m long and 2.7 m wide channel. Here, we also used a constant discharge and unimodal sediments, but with gravel ranging in size from 2 to 45 mm. In both experiments, we first leveled the bed and supplied sediments at a steady rate, allowed bar forms to develop, and then eliminated the sediment supply in an attempt to model a dam closure. In the larger-scale flume, we also attempted to determine how much sediment needed to be added to the channel to mitigate the effects of reduced sediment supply. Initial hydraulic conditions were optimized to promote alternate bar development (i.e. width to depth ratio w/d > 15 and full mobility of the bed surface grain sizes) and relative roughness (D/d, D is bed sediment size) was <<1 in both experiments. As in previous experiments on bar growth, the developed alternate bars had an amplitude similar to the flow depth and, after some initial downstream migration, became stationary. Bar top surfaces were heavily armored, while adjacent

  4. Effect of replacing surface inlets with blind or gravel inlets on sediment and phosphorus subsurface drainage losses.

    PubMed

    Feyereisen, Gary W; Francesconi, Wendy; Smith, Douglas R; Papiernik, Sharon K; Krueger, Erik S; Wente, Christopher D

    2015-03-01

    Open surface inlets that connect to subsurface tile drainage systems provide a direct pathway for movement of sediment, nutrients, and agrochemicals to surface waters. This study was conducted to determine the reduction in drainage effluent total suspended sediment (TSS) and phosphorus (P) concentrations and loads when open surface inlets were replaced with blind (in gravel capped with 30 cm of soil) or gravel (in very coarse sand/fine gravel) inlets. In Indiana, a pair of closed depressions in adjacent fields was fitted with open inlet tile risers and blind inlets in 2005 and monitored for flow and water chemistry. Paired comparisons on a storm event basis during the growing season for years 2006 to 2013 showed that TSS loads were 40.4 and 14.4 kg ha event for tile risers and blind inlets, respectively. Total P (TP) and soluble reactive P (SRP) loads were 66 and 50% less for the blind inlets, respectively. In Minnesota, TSS and SRP concentrations were monitored for 3 yr before and after modification of 24 open inlets to gravel inlets in an unreplicated large-field on-farm study. Median TSS concentrations were 97 and 8.3 mg L and median SRP concentrations were 0.099 and 0.064 mg L for the open inlet and gravel inlet periods, respectively. Median TSS and SRP concentrations were elevated for snowmelt vs. non-snowmelt seasons for open and gravel inlets. Both replacement designs reduced suspended sediment and P concentrations and loads. The Indiana study suggests blind inlets will be effective beyond a 10-yr service life.

  5. Three Storm Surge Events during Late Holocene in Shelly Gravel Sediments of the most Southern Coast of Korean Peninsula

    NASA Astrophysics Data System (ADS)

    Yang, Dong Yoon

    2015-04-01

    Super Typhoon Haiyan which occurred in November, 2013 left as many as 5,200 people dead and destroyed towns across the Philippines. However, because of rapid climate change, we cannot disregard such a super typhoon strike probability in Korean Peninsula. If we can detect the frequency and periodicity of paleo-geohazards recorded in sediments, the extreme geohazards can be predicted and its damage can be somewhat mitigated. The geology, geochemistry and mineralogy of the island sediments ahead of Yeongjeon coast, Haenam-gun, the most southern part, Korean peninsula were investigated. Shells from the three shelly gravel layers were used for 14C age dating and cube samples were collected at 5-10cm intervals for measuring the magnetic susceptibility, grain size distribution and geochemical analyses at the study site. Granitic gneiss clasts of debris flow mixed with the weathered tuffaceous materials on the eroded face of tuff rock. The sediments of Pleistocene were also eroded almost horizontally and unconformably covered by late Holocene shelly gravel deposits characterized by some kind of shells and unsorted sub-rounded or rounded gravels to pebbles. The horizontal erosion face is 2.2m in elevation and the current erosion face of beach was observed at 1.2m in elevation. This indicates that the former erosion face would have been formed at higher sea level than those of latter one by the similar mechanism of current erosion in the study site. Three shelly gravel layers overlie the erosion face from 2.2m to 2.9m in elevation. The reflected water energy caused by stronger storm would have been needed for delivering gravels and cobbles to the erosion face. Three shell layers dated as 3200 yr BP, 1900 yr BP, and 1700 yr BP, respectively. Four sedimentary units, from unit 1 to 4 in ascending order, are distinguished on the basis of sedimentary textures, shell contents, grain size distribution and vertical color variations. The sand ratios in the grain size distribution

  6. Utilization of Landsat multispectral data in geobotanical investigations - The location of ironstone gravel in the Sam Houston National Forest, Texas

    NASA Technical Reports Server (NTRS)

    Cibula, William G.; Lucas, Wilmuth

    1990-01-01

    The location of ironstone gravel deposits by remote sensing (using Landsat MSS frames) over a heavily vegetated terrain is demonstrated. It is suggested that the spectral class exhibited on an analyzed Landsat frame (acquired during a protracted drought period) relates to water stressed regions within the upland pine forest type as a result of the near-surface geology of the areas where ironstone gravel is present. It is also suggested that the presence of both the ironstone aggregate and the associated plinthite hardpan layer may be responsible for the absence of longleaf pine on these sites of the Sam Houston National Forest, as compared to similar sites a few km away.

  7. Utilization of Landsat multispectral data in geobotanical investigations - The location of ironstone gravel in the Sam Houston National Forest, Texas

    NASA Technical Reports Server (NTRS)

    Cibula, William G.; Lucas, Wilmuth

    1990-01-01

    The location of ironstone gravel deposits by remote sensing (using Landsat MSS frames) over a heavily vegetated terrain is demonstrated. It is suggested that the spectral class exhibited on an analyzed Landsat frame (acquired during a protracted drought period) relates to water stressed regions within the upland pine forest type as a result of the near-surface geology of the areas where ironstone gravel is present. It is also suggested that the presence of both the ironstone aggregate and the associated plinthite hardpan layer may be responsible for the absence of longleaf pine on these sites of the Sam Houston National Forest, as compared to similar sites a few km away.

  8. Functions of slags and gravels as substrates in large-scale demonstration constructed wetland systems for polluted river water treatment.

    PubMed

    Ge, Yuan; Wang, Xiaochang; Zheng, Yucong; Dzakpasu, Mawuli; Zhao, Yaqian; Xiong, Jiaqing

    2015-09-01

    The choice of substrates with high adsorption capacity, yet readily available and economical is vital for sustainable pollutants removal in constructed wetlands (CWs). Two identical large-scale demonstration horizontal subsurface flow (HSSF) CWs (surface area, 340 m(2); depth, 0.6 m; HLR, 0.2 m/day) with gravel or slag substrates were evaluated for their potential use in remediating polluted urban river water in the prevailing climate of northwest China. Batch experiments to elucidate phosphorus adsorption mechanisms indicated a higher adsorption capacity of slag (3.15 g/kg) than gravel (0.81 g/kg), whereby circa 20 % more total phosphorus (TP) removal was recorded in HSSF-slag than HSSF-gravel. TP removal occurred predominantly via CaO-slag dissolution followed by Ca phosphate precipitation. Moreover, average removals of chemical oxygen demand and biochemical oxygen demand were approximately 10 % higher in HSSF-slag than HSSF-gravel. Nevertheless, TP adsorption by slag seemed to get quickly saturated over the monitoring period, and the removal efficiency of the HSSF-slag approached that of the HSSF-gravel after 1-year continuous operation. In contrast, the two CWs achieved similar nitrogen removal during the 2-year monitoring period. Findings also indicated that gravel provided better support for the development of other wetland components such as biomass, whereby the biomass production and the amount of total nitrogen (TN; 43.1-59.0 g/m(2)) and TP (4.15-5.75 g/m(2)) assimilated by local Phragmites australis in HSSF-gravel were higher than that in HSSF-slag (41.2-52.0 g/m(2) and 3.96-4.07 g/m(2), respectively). Overall, comparable pollutant removal rates could be achieved in large-scale HSSF CWs with either gravel or slag as substrate and provide a possible solution for polluted urban river remediation in northern China.

  9. Invertebrate drift during in-channel gravel mining: the Upper River Cinca (Southern Pyrenees)

    NASA Astrophysics Data System (ADS)

    Béjar, Maria; Gibbins, Chris; Vericat, Damià; Batalla, Ramon J.; Muñoz, Efrén; Ramos, Ester; Lobera, Gemma; Andrés López-Tarazón, Jose; Piqué, Gemma; Tena, Álvaro; Buendía, Cristina; Rennie, Colin D.

    2015-04-01

    Invertebrate drift has been widely studied as an important mechanism to structure the benthic assemblages and as a part of invertebrate behavior in fluvial systems. River channel disturbance is considered the main factor affecting the organization of riverine communities and contributes to key ecological processes. However, little is known about involuntary drift associated to bed disturbance due to the difficulties associated with sampling during floods. In-channel gravel mining offers an opportunity to study involuntary drift associated not only to local bed disturbances but also to sudden changes on suspended sediment concentrations and flow. High suspended sediment concentrations and sudden changes in flow also prompt drift due to the limiting conditions (i.e. lack of oxygen, hydric stress). Within this context, invertebrate drift was monitored in the Upper River Cinca (Southern Pyrenees) during two gravel mining activities performed in summer 2014. The data acquisition design includes: drift, suspended sediment, bedload, bed mobility and flow. Data was acquired before, during and after mining at different sampling locations located upstream and downstream the perturbation. Drift and suspended sediment transport were sampled at 5 sections: 1 control site upstream the mining and 4 downstream. Bedload samples were collected just downstream the channel where gravels were extracted. Bed mobility and changes on topography were assessed by means of GPS-aDcp and repeat topographic surveys. Discharge was continuously recorded 2.5 km downstream the mining location. Additionally, two turbidity meters registered water turbidity at 15 minute intervals in two of the four sampling sections located downstream. This experimental design provides data on the spatial and temporal variability of drift associated to a local bed disturbance that (i) changes the distribution of flow across the section where mining was performed, (ii) increase substantially suspended sediment

  10. Impact of gravels and organic matter on the thermal properties of grassland soils in southern France

    NASA Astrophysics Data System (ADS)

    Calvet, J.-C.; Fritz, N.; Berne, C.; Piguet, B.; Maurel, W.; Meurey, C.

    2015-06-01

    Soil moisture is the main driver of temporal changes in values of the soil thermal conductivity. The latter is a key variable in land surface models (LSMs) used in hydrometeorology, for the simulation of the vertical profile of soil temperature in relation to soil moisture. Shortcomings in soil thermal conductivity models tend to limit the impact of improving the simulation of soil moisture in LSMs. Models of the thermal conductivity of soils are affected by uncertainties, especially in the representation of the impact of soil properties such as the volumetric fraction of quartz (q), soil organic matter, and gravels. As soil organic matter and gravels are often neglected in LSMs, the soil thermal conductivity models used in most LSMs represent the mineral fine earth, only. Moreover, there is no map of q and it is often assumed that this quantity is equal to the volumetric fraction of sand. In this study, q values are derived by reverse modelling from the continuous soil moisture and soil temperature sub-hourly observations of the Soil Moisture Observing System - Meteorological Automatic Network Integrated Application (SMOSMANIA) network at 21 grassland sites in southern France, from 2008 to 2015. The soil temperature observations are used to retrieve the soil thermal diffusivity (Dh) at a depth of 0.10 m in unfrozen conditions, solving the thermal diffusion equation. The soil moisture and Dh values are then used together with the measured soil properties to retrieve soil thermal conductivity (λ) values. For ten sites, the obtained λ value at saturation (λsat) cannot be retrieved or is lower than the value corresponding to a null value of q, probably in relation to a high density of grass roots at these sites or to the presence of stones. For the remaining eleven sites, q is negatively correlated with the volumetric fraction of solids other than sand. The impact of neglecting gravels and organic matter on λsat is assessed. It is shown that these factors have a

  11. Transient Responses of Gravel Bars to Increases in Sediment Supply - Field & Flume

    NASA Astrophysics Data System (ADS)

    Podolak, C.

    2010-12-01

    Bedforms in a gravel-bed river respond to a combination of water discharge, the rate and size of sediment supply, and valley-scale geometry. This study investigates bar response to an increase in sediment supply. In a large flume (2.75 m wide) with a plane bed of mixed sand and gravel (gravel D50 = 10 mm; 15% sand), alternate bars were formed by inducing a slight perturbation in the flow at the upstream end. After the bars and sediment flux reached a steady state, sediment supply was increased (from 45 kg/min to 70 kg/min). After the bed and sediment flux reached steady state, sediment supply was again increased (from 70 kg/min to 140 kg/min). Throughout the experiment high-frequency (1 Hz) measurements of the sediment flux, as well as moderate frequency (every 90 minutes) measurements of the bed topography were made. As the channel increased transport capacity to match the increased sediment supply, the initial bed adjustment was an increase in slope with near uniform deposition in the cross-stream direction. The bed then evolved to a steady-state configuration in which the locations and dimensions of the bars and pools were very similar to the pre-augmentation condition. During the adjustment process, the cross-stream relief initially decreased, the bar wavelengths decreased, and the bar celerity increased. The evolution from the lower-relief interim state to the post-augmentation steady state was reminiscent of initial bar development from a plane bed. A similar sequence of bed adjustment was observed on the Sandy River, Oregon, following a large increase in sediment flux due to the 2007 Marmot Dam removal. Measurements of bedform evolution immediately downstream of the dam show a transition from a long high-relief lateral bar along the right bank, to a lower-relief multiple short wavelength mid-channel bars, finally back to a long high-relief lateral bar along the right bank, albeit 4-5 meters higher than the original. Previous work on bedform response to

  12. Leaching of Natural Gravel and Concrete by CO2 - Experimental Design, Leaching Behaviour and Dissolution Rates

    NASA Astrophysics Data System (ADS)

    Fuchs, Rita; Leis, Albrecht; Mittermayr, Florian; Harer, Gerhard; Wagner, Hanns; Reichl, Peter; Dietzel, Martin

    2015-04-01

    The durability of building material in aggressive aqueous environments is a key factor for evaluating the product quality and application as well as of high economic interest. Therefore, aspects of durability have been frequently investigated with different approaches such as monitoring, modelling and experimental work. In the present study an experimental approach based on leaching behaviour of natural calcite-containing siliceous gravel used as backfill material in tunnelling and sprayed concrete by CO2 was developed. CO2 was introduced to form carbonic acid, which is known as an important agent to induce chemical attack. The goals of this study were (i) to develop a proper experimental design to survey the leaching of building materials on-line, (ii) to decipher individual reaction mechanisms and kinetics and (iii) to estimate time-resolved chemical resistance of the used material throughout leaching. A combined flow through reactor unit was successfully installed, where both open and closed system conditions can be easily simulated by changing flow directions and rates. The chemical compositions of the experimental solutions were adjusted by CO2 addition at pHstat conditions and monitored in-situ by pH/SpC electrodes and by analysing the chemical composition of samples throughout an experimental run. From the obtained data e.g. dissolution rates with respect to calcite were obtained for the gravel material, which were dependent on the individual calcite content of the leached material. The rates were found to reflect the flow rate conditions, and the kinetic data lay within the range expected from dissolution experiments in the CaCO3-CO2-H2O system. In case of concrete the reactions throughout the leaching experiment were complex. Coupled dissolution and precipitation phenomena (e.g. portlandite dissolution, calcite formation) occurred. The coupled reactions can be followed by the evolution of the solution chemistry. The overall rates of elemental removal from

  13. The impact of aquatic animals on sediment transport in gravel-bed rivers

    NASA Astrophysics Data System (ADS)

    Johnson, Matthew; Rice, Stephen; Pledger, Andrew

    2014-05-01

    Invertebrate animals have an important and complex role in altering the physical and biochemical environment of marine and freshwater sediments. A database has been compiled which aims to include all published articles that consider how macroinvertebrates alter aquatic systems. The database contains 2300 entries spanning over 120 years of study and representing 800 species. However, only 24 studies focus on invertebrate animals altering geomorphic processes in streams. This is despite the fact that invertebrates are ubiquitous in temperate and tropical rivers; they regularly occur in high densities; and are known to interact with substrates in a multitude of ways; for example when burrowing, moving and foraging for food. Here, we present two examples that demonstrate the potential biogeomorphic significance of invertebrates in rivers. First, the activity of signal crayfish (Pacifastacus leniusculus), a globally widespread invasive crustacean, altered the structure and topography of fluvial substrates in flume experiments. As a result of crayfish destroying grain-scale structures, twice as much material was entrained from disturbed gravel substrates in comparison to control surfaces that had not been exposed to crayfish. Second, Hydropsychid caddisfly larvae bind grains together with silk, which is spun for a variety of purposes including the creation of nets to catch organic matter from the flow. Fine gravels (2-6 mm) that were colonised by natural densities of caddisfly, required significantly greater shear stresses to be mobilised in comparison to uncolonised, control gravels. Whilst these examples demonstrate the potential for invertebrates to alter sediment transport in rivers, their impacts need to be assessed in field environments and at larger scales in order to fully appreciate their significance. Long-term monitoring of radio-tagged crayfish and suspended sediment transport in the Brampton arm of the River Nene suggests that signal crayfish are important

  14. Sampling surface and subsurface particle-size distributions in wadable gravel-and cobble-bed streams for analyses in sediment transport, hydraulics, and streambed monitoring

    Treesearch

    Kristin Bunte; Steven R. Abt

    2001-01-01

    This document provides guidance for sampling surface and subsurface sediment from wadable gravel-and cobble-bed streams. After a short introduction to streams types and classifications in gravel-bed rivers, the document explains the field and laboratory measurement of particle sizes and the statistical analysis of particle-size distributions. Analysis of particle...

  15. 43 CFR 3503.16 - May I obtain permits or leases for sand and gravel in Nevada under the terms of this part?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 43 Public Lands: Interior 2 2011-10-01 2011-10-01 false May I obtain permits or leases for sand... Leasing Available Areas Under Blm Management § 3503.16 May I obtain permits or leases for sand and gravel...; BLM will consider any new applications for sand and gravel under the regulations at part 3600 of this...

  16. 43 CFR 3503.16 - May I obtain permits or leases for sand and gravel in Nevada under the terms of this part?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 43 Public Lands: Interior 2 2014-10-01 2014-10-01 false May I obtain permits or leases for sand... Leasing Available Areas Under Blm Management § 3503.16 May I obtain permits or leases for sand and gravel...; BLM will consider any new applications for sand and gravel under the regulations at part 3600 of this...

  17. 43 CFR 3503.16 - May I obtain permits or leases for sand and gravel in Nevada under the terms of this part?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 43 Public Lands: Interior 2 2012-10-01 2012-10-01 false May I obtain permits or leases for sand... Leasing Available Areas Under Blm Management § 3503.16 May I obtain permits or leases for sand and gravel...; BLM will consider any new applications for sand and gravel under the regulations at part 3600 of this...

  18. 43 CFR 3503.16 - May I obtain permits or leases for sand and gravel in Nevada under the terms of this part?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 43 Public Lands: Interior 2 2013-10-01 2013-10-01 false May I obtain permits or leases for sand... Leasing Available Areas Under Blm Management § 3503.16 May I obtain permits or leases for sand and gravel...; BLM will consider any new applications for sand and gravel under the regulations at part 3600 of this...

  19. Distribution and stability of potential salmonid spawning gravels in steep boulder-bed streams of the eastern Sierra Nevada. [Salmo trutta; Oncorhynchus mykiss

    SciTech Connect

    Kondolf, G.M. ); Cada, G.F.; Sale, M.J. ); Felando, T. )

    1991-03-01

    Interest in small hydroelectric development (< 5 MW) has recently focused attention on steep streams and the resident trout populations they contain. High-gradient boulder-bed streams have been the sites of relatively few studies of salmonid spawning habitat, although they have geomorphic and hydraulic characteristics - and therefore gravel distributions - that are quite different from the more commonly described lower-gradient channels. The authors documented gravel distribution in seven high-gradient stream reaches in the eastern Sierra Nevada. Gravels occurred only in locations characterized by relatively low shear stress; they formed small pockets in sites of low divergence and larger deposits upstream of natural hydraulic controls. In 1986 (a wet year), all tracer gravels placed in gravel pockets at nine sites on four streams were completely swept away, and substantial scour, fill, and other channel changes occurred at many sites. In 1987 (a dry year), tracer gravels and the channel cross sections were generally stable. Periodic mobility of gravel may explain why brown trout Salmo trutta are more abundant than rainbow trout Oncorhychus mykiss in the study reaches, where high flows occur every May and June during snowmelt. Brown trout are fall spawners, and their fry emerge long before the high snowmelt flows, whereas rainbow trout are spring spawners whose eggs are in the gravel, and thus vulnerable to scour, during snowmelt flows.

  20. Use of macrophyte plants, sand & gravel materials in constructed wetlands for greywater treatment

    NASA Astrophysics Data System (ADS)

    Qomariyah, S.; Ramelan, AH; Sobriyah; Setyono, P.

    2017-02-01

    Greywater discharged without any treatments into drainage channels or natural water bodies will lead to environmental degradation and health risk. Local macrophyte plants combined with natural materials of sand and gravel have been used in a system of constructed wetland for the treatment of the greywater. This paper presents the results of some studies of the system carried out in Indonesia, Thailand, and Costa Rica. The studies demonstrate the success of the constructed wetland systems in removing some pollutants of BOD, COD, TSS, pathogen, and detergent. The studies resulted in the treated water in a level of treatment that fulfils the requirement of the local standards for wastewater reuse as irrigation water, fishery, or other outdoor needs.

  1. A study of radioactivity in modern stream gravels and its possible application as a prospecting method

    USGS Publications Warehouse

    Chew, Randall T.

    1955-01-01

    Traverses along some streams of the Colorado Plateau in areas known to contain minable uranium deposits show that anomalous radiation in the stream gravels can be detected with a suitable counter downstream from the deposits. The amount of radiation is influenced by the size of the uranium deposit, the size of the drainage area of the stream, the grain size of the sediments, and the lithology of the rocks over which the stream flows. The spacing of the stations where readings are taken is controlled by the size of the stream, and special readings are also taken directly downstream from important tributaries. An anomaly is empirically defined as a 10 percent rise over background. Radioactive material from large uranium deposits has been detected as much as 1 mile downstream. Radioactive material from smaller deposits is detachable over shorter distances. The method is slow but appears to be a useful prospecting tool under restricted conditions.

  2. Observations of backscatter from sand and gravel seafloors between 170 and 250 kHz.

    PubMed

    Weber, Thomas C; Ward, Larry G

    2015-10-01

    Interpreting observations of frequency-dependence in backscatter from the seafloor offers many challenges, either because multiple frequencies are used for different observations that will later be merged or simply because seafloor scattering models are not well-understood above 100 kHz. Hindering the understanding of these observations is the paucity of reported, calibrated acoustic measurements above 100 kHz. This manuscript seeks to help elucidate the linkages between seafloor properties and frequency-dependent seafloor backscatter by describing observations of backscatter collected from sand, gravel, and bedrock seafloors at frequencies between 170 and 250 kHz and at a grazing angle of 45°. Overall, the frequency dependence appeared weak for all seafloor types, with a slight increase in seafloor scattering strength with increasing frequency for an area with unimodal, very poorly to moderately well sorted, slightly granular to granular medium sand with significant amounts of shell debris and a slight decrease in all other locations.

  3. Use of nutrient response techniques to assess the effectiveness of chlorination of rapid sand filter gravel.

    PubMed Central

    Lytle, M S; Adams, J C; Dickman, D G; Bressler, W R

    1989-01-01

    A direct viable counting method was used to rapidly assess the effectiveness of chlorination of biofilms on rapid sand filter gravel. A total of 50% of the cells were nutrient responsive after exposure to 0.5 mg of chlorine per liter, while this value was 25% after exposure to 25 mg of chlorine per liter. A large variation was seen in the numbers of nutrient-responsive cells on different rocks. More cells attached to the sandblasted side of marbles than to the smooth side, but there was no difference in eight of nine cases in the proportion of survival to chlorination between the two different sides. The effectiveness of chlorination appeared to be influenced by the species of bacterium in the biofilm. PMID:2705772

  4. Coral-gravel storm ridges: examples from the tropical Pacific and Caribbean

    USGS Publications Warehouse

    Richmond, Bruce M.; Morton, Robert A.

    2007-01-01

    Extreme storms in reef environments have long been recognized as a mechanism for depositing ridges of reef-derived coarse clastic sediment. This study revisits the storm ridges formed by Tropical Cyclone Bebe on Funafuti, Tuvalu and Tropical Cyclone Ofa on Upolu, Western Samoa in the South Pacific, and Hurricane Lenny on Bonaire, Netherlands Antilles in the Caribbean. Ridge characteristics produced by these storms include: heights of 1–4 m, widths of 8–50 m, and lengths up to 18 km. The ridges tend to be higher and steeper on their landward margins than on their seaward margins and are composed mostly of re-worked coral rubble derived from reef front settings with smaller amounts of fresh broken coral (5–30%). Characteristics of these modern gravel storm ridges can be used to help identify ancient storm deposits and to differentiate between other coarse-grained deposits such as those created by tsunamis.

  5. Effect of setback distance on ability of gravel trenches to intercept contaminated groundwater.

    PubMed

    Hudak, Paul F

    2005-05-01

    Computer simulations tested the ability of gravel interceptor trenches to capture a plume of contaminated groundwater. The plume had a maximum length and width of 87 and 19 m, respectively. In alternate simulations, one-meter wide trenches were located 5, 10, 20, and 50 m downgradient of the plume. A minimum trench length and time required to capture the plume was determined for each location (setback). The plume was considered captured if it passed entirely through a trench. A 21 m-long trench captured the plume at setbacks of 5 and 10 m. Minimum trench length increased to 23 and 25 m at setbacks of 20 and 50 m, respectively. Increased contaminant spreading with distance traveled dictated longer trenches at larger setbacks. Results of this study suggest that, at settings where contaminant plumes are carefully monitored and spatially defined, passive interceptor trenches should be close to a plume's leading tip and slightly longer than the maximum width of the plume.

  6. Performance of upflow gravel filtration in multi-stage filtration plants.

    PubMed

    Sánchez, L D; Visscher, J T; Rietveld, L C

    2015-01-01

    This paper presents the results of a study of four full-scale upflow gravel filters that are part of full-scale multi-stage filtration. The study explored the design criteria, the operation and maintenance (O&M) practices, and the performance of the systems. Findings showed that most design criteria and O&M procedures are following the recommendations as presented in the literature but several diversions were also identified. Performance data showed that removal efficiencies were on the low side when compared to the literature, possibly because of the good influent quality water that was treated. Cleaning efficiency was analyzed and the overall conclusion is that an adjustment of the design criteria and O&M procedures is needed to enhance system performance. This includes drainage system design, surface cleaning by weir, and filter bed cleaning to allow a reduction in cleaning cycles and an improvement in operation control.

  7. The impact of hydrograph variability and frequency on the morphodynamics of gravel-bed rivers

    NASA Astrophysics Data System (ADS)

    Plumb, Ben; Franca, Mário; Juez, Carmelo; Schleiss, Anton; Annable, William

    2016-04-01

    Hydromodification is the alteration of natural watershed hydrologic processes, which is known to change the way that water naturally enters watercourses. In the case of urbanization, this change has manifested through individual hydrograph characteristics (resulting in a decrease in duration and in the time-to-peak), as well as through the increase of the frequency of morphologically significant flood events. These hydrologic changes have been documented to impact the morphology of gravel-bed rivers, often resulting in channel degradation. However, the actual extent that urbanization changes bedload transport characteristics, which is known to be the most important driver of channel morphology, are not yet known. A laboratory experiment was undertaken in a 0.5m gravel-bed flume with sediment feed using a single poorly sorted bimodal sediment mixture in order to evaluate the impacts of changing hydrograph characteristics and frequencies on bedload transport and bed morphology. The hydrograph characteristics and frequencies were derived from long term stream-gauge records of urbanizing gravel-bed watercourses. These records are long enough to therefore be representative of the actual relative changes of the hydrologic regime; from an unaltered to a highly hydromodified system. A series of four hydrologic scenarios were established, representing 10 years of morphologically significant discharge events for four different stages of urban land-use, and corresponding hydrologic regimes. Each scenario begins with the same initial conditions and is allowed to evolve naturally with each successive hydrograph. For each scenario, the hydrograph duration and unsteadiness were varied, while peak discharge remained constant for all scenarios. In addition, the number of hydrographs ranged from nine to 33 for the unaltered to the most hydromodified scenarios, respectively. Discharge was measured constantly with a v-notch weir, and varied with a calibrated valve relationship

  8. Comparison of mineral resources calculation methods for different genetic types of gravel and sand deposits

    NASA Astrophysics Data System (ADS)

    Patashova, T.

    2009-04-01

    Calculation of mineral resources and their proper assessment is relevant, since the stock of resources determines the economic independence of the state. I would like present the work wherein discusses gravel and sand deposits of different genetic type (kames, eskers, marginal glaciofluvial ridges, sandurs, glaciofluvial deltas and redrifted glaciofluvial aeolian formations). Their geological structure and formation conditions have been assessed; quality characteristics of mineral resources have been analysed; calculation of resources has been performed by applying most popular resources calculating methods used in Lithuania up to now, such as those of geological blocks, profiles and isolines, as well as the up-to-date GRID method created on the basis of triangle method in GIS environment. Comparison of resources assessed by different methods has revealed their advantages and disadvantages, their availability subject to deposits‘genetic types.

  9. Comparison of mineral resources calculation methods for different genetic types of gravel and sand deposits

    NASA Astrophysics Data System (ADS)

    Patašova, Tatjana; Jurgaitis, Algirdas

    2008-01-01

    Calculation of mineral resources and their proper assessment is relevant, since the stock of resources determines the economic independence of the state. The present work discusses gravel and sand deposits of different genetic type (kames, eskers, marginal glaciofluvial ridges, sandurs, glaciofluvial deltas and redrifted glaciofluvial aeolian formations). Their geological structure and formation conditions have been assessed; quality characteristics of mineral resources have been analysed; calculation of resources has been performed by applying old methods used in Lithuania up to now, such as those of geological blocks, profiles and isolines, as well as the up-to-date GRID method created on the basis of the triangle method in GIS environment. Comparison of resources assessed by different methods has revealed their advantages and disadvantages.

  10. Frequency-wavenumber velocity spectra, Taylor's hypothesis, and length scales in a natural gravel bed river

    NASA Astrophysics Data System (ADS)

    Macmahan, Jamie; Reniers, Ad; Ashley, Will; Thornton, Ed

    2012-09-01

    Macroscale turbulent coherent flow structures in a natural fast-flowing river were examined with a combination of a novel 2 MHz Acoustic Doppler Beam (ADB) and a Maximum Likelihood Estimator (MLE) to characterize the streamwise horizontal length scales and persistence of coherent flow structures by measuring the frequency (f)-streamwise-wavenumber (ks) energy density velocity spectrum, E(f, ks), for the first time in natural rivers. The ADB was deployed under a range of Froude numbers (0.1-0.6) at high Reynolds numbers (˜106) based on depth and velocity conditions within a gravel bed reach of the Kootenai River, Idaho. The MLE employed on the ADB data increased our ability to describe river motions with relatively long (>10 m) length scales in ˜1 m water depths. The E(f, ks) spectra fell along a ridge described by V = f/ks, where Vis the mean velocity over depth, consistent with Taylor's hypothesis. New, consistent length scale measures are defined based on averaged wavelengths of the low-frequencyE(f, ks) and coherence spectra. Energetic (˜50% of the total spectral energy), low-frequency (f < 0.05 Hz) streamwise motions were found. Mean length scales,Lm, compared with the depth, h, are significantly larger than previously suggested for macroturbulence with Lm/h˜ 28-118. Although the energy appears as low-pass white noise, it is streamwise coherent along the length of the array. In fast flows with velocities > 1 m/s,Lmwere found to be significantly longer than their corresponding coherence lengths, suggesting that the turbulent structures evolve rapidly under these conditions. This is attributed to the stretching and concomitant deformation of preexisting macroturbulent motions by the ubiquitous bathymetry-induced spatial flow accelerations present in a natural gravel bed river.

  11. Investigation of bar formation on a reconfigured gravel-bed river

    NASA Astrophysics Data System (ADS)

    Erwin, S.; Schmidt, J. C.; Wilcock, P.

    2009-12-01

    A 16 km reach of the Provo River (Utah) between Jordanelle Dam and Deer Creek Reservoir has been entirely reconstructed over the past eight years. Although a similar channel design was used through the entire reach, the upstream portion receives essentially no sediment supply whereas the lower portion receives a large sediment supply from an intervening unrestored reach. This provides an opportunity to observe channel change on a large gravel-bed river in response to well-documented differences in sediment supply. The upper portion of the river has remained largely static, whereas the lower reach has experienced active point bar growth in the constructed bends. Point bars grew initially in the upstream end of the reach, and bar growth has extended progressively downstream with subsequent flow. Here, we document the sediment flux and storage in the different reaches and compare these results to observed changes in point bar size. During spring 2009, releases from Jordanelle Dam, were manipulated to create a controlled flood during which we systematically measured sediment transport. We measured bed load and suspended load at the upstream and downstream boundaries of a 4-km reach where gravel is known to be accumulating. Transport was measured on the rising and falling limbs of the flood at 200 ft3/s increments between 800 and 1800 ft3/s. Bed load data were collected using a Toutle River (TR-2) sampler, deployed from a cataraft-based sampling platform. Suspended sediment was collected with a DH-59 depth-integrated sampler. Channel morphodynamic adjustments are based on measurements of channel change using a combination of aerial LiDaR, ground-based LiDaR, and RTK GPS data. Preliminary analysis of sediment transport data indicates that approximately 10 - 30% of the sediment entering the upstream of our study reach is not exiting at the downstream end of the reach, indicating that the channel is still adjusting to the upstream sediment load.

  12. Temporal and spatial variability in thalweg profiles of a gravel-bed river

    USGS Publications Warehouse

    Madej, Mary Ann

    1999-01-01

    This study used successive longitudinal thalweg profiles in gravel-bed rivers to monitor changes in bed topography following floods and associated large sediment inputs. Variations in channel bed elevations, distributions of residual water depths, percentage of channel length occupied by riffles, and a spatial autocorrelation coefficient (Moran's I) were used to quantify changes in morphological diversity and spatial structure in Redwood Creek basin, northwestern California. Bed topography in Redwood Creek and its major tributaries consists primarily of a series of pools and riffles. The size, frequency and spatial distribution of the pools and riffles have changed significantly during the past 20 years. Following large floods and high sediment input in Redwood Creek and its tributaries in 1975, variation in channel bed elevations was low and the percentage of the channel length occupied by riffles was high. Over the next 20 years, variation in bed elevations increased while the length of channel occupied by riffles decreased. An index [(standard deviation of residual water depth/bankfull depth) × 100] was developed to compare variations in bed elevation over a range of stream sizes, with a higher index being indicative of greater morphological diversity. Spatial autocorrelation in the bed elevation data was apparent at both fine and coarse scales in many of the thalweg profiles and the observed spatial pattern of bed elevations was found to be related to the dominant channel material and the time since disturbance. River reaches in which forced pools dominated, and in which large woody debris and bed particles could not be easily mobilized, exhibited a random distribution of bed elevations. In contrast, in reaches where alternate bars dominated, and both wood and gravel were readily transported, regularly spaced bed topography developed at a spacing that increased with time since disturbance. This pattern of regularly spaced bed features was reversed

  13. Evolution of gravel-bed channels in response to flash floods in dry environments

    NASA Astrophysics Data System (ADS)

    Salomon, Reut; Morin, Efrat; Enzel, Yehouda; Haviv, Itai

    2016-04-01

    Longitudinal profiles of alluvial channels may be altered rapidly in response to base-level lowering or changes in streamflow regime. Previous models simulating the response to such changes assumed steady and uniform streamflow discharge, or used a calibrated diffusion coefficient as a proxy for stream discharge. Such models do not account for intra and inter annual variance of flash flood volume and peak discharge which is typically high in channels of dry environments. We developed a new model for evolution of longitudinal profiles of gravel-bed channels combining kinematic wave flood routing with sediment transport based on the Meyer-Peter-Muller equation. The model predicts changes in channel longitudinal profile in response to changing streamflow regimes and base-level lowering rates. We have adopted a stochastic approach by formulating a "flash flood generator" which produces a synthetic data series of floods based on the probability distribution of peak discharge and hydrograph properties in a specific basin. The model was applied to the lower reach of Nahal Darga gravel-bed channel which drains into the Dead Sea Lake and is located in a dry climate regime. During the last 40 years, the initial uniform-gradient profile of this reach has changed to a convex profile as a result of a drastic artificial lowering of the Dead Sea level at a rate of 1 m/y. Measured channel profiles at several points in time were used for the model evaluation. The effect of different scenarios of lake level drop and of flash flood regime on the channel profile has been examined. The modeling results indicate a wide range of possible channel profiles due to the natural flow variance under a given flow regime. Extreme flow events play a major role on the channel profile evolution. Nevertheless, the effective discharge at the Darga channel, consists of floods with medium peak discharge and a recurrence interval of ~10 years.

  14. Comparison of Machine Learning methods for incipient motion in gravel bed rivers

    NASA Astrophysics Data System (ADS)

    Valyrakis, Manousos

    2013-04-01

    Soil erosion and sediment transport of natural gravel bed streams are important processes which affect both the morphology as well as the ecology of earth's surface. For gravel bed rivers at near incipient flow conditions, particle entrainment dynamics are highly intermittent. This contribution reviews the use of modern Machine Learning (ML) methods implemented for short term prediction of entrainment instances of individual grains exposed in fully developed near boundary turbulent flows. Results obtained by network architectures of variable complexity based on two different ML methods namely the Artificial Neural Network (ANN) and the Adaptive Neuro-Fuzzy Inference System (ANFIS) are compared in terms of different error and performance indices, computational efficiency and complexity as well as predictive accuracy and forecast ability. Different model architectures are trained and tested with experimental time series obtained from mobile particle flume experiments. The experimental setup consists of a Laser Doppler Velocimeter (LDV) and a laser optics system, which acquire data for the instantaneous flow and particle response respectively, synchronously. The first is used to record the flow velocity components directly upstream of the test particle, while the later tracks the particle's displacements. The lengthy experimental data sets (millions of data points) are split into the training and validation subsets used to perform the corresponding learning and testing of the models. It is demonstrated that the ANFIS hybrid model, which is based on neural learning and fuzzy inference principles, better predicts the critical flow conditions above which sediment transport is initiated. In addition, it is illustrated that empirical knowledge can be extracted, validating the theoretical assumption that particle ejections occur due to energetic turbulent flow events. Such a tool may find application in management and regulation of stream flows downstream of dams for stream

  15. Unintended consequences of restoration: loss of riffles and gravel substrates following weir installation.

    PubMed

    Salant, Nira L; Schmidt, John C; Budy, Phaedra; Wilcock, Peter R

    2012-10-30

    We used pre- and post-restoration channel surveys of the Donner und Blitzen River, Oregon, to evaluate the effects of grade-control structures on channel morphology and baseflow habitat conditions for native redband trout and other aquatic biota. Six years after installation, we found that the channel had a smaller proportion of riffles and pools and less gravel substrate, combined with an increase in the proportion of flat waters and consolidated clay on the bed surface. Both local scour downstream from weirs and backwater effects upstream from weirs appear to have caused the general flattening and fining of the channel. A direct-step backwater calculation indicates that backwaters extended to the upstream weir at both low and high flows, creating long sections of flat water separated by short, steep drops. Despite backwater effects, a comparison of longitudinal profiles before and six years after weir installation showed bed erosion downstream of nearly all weirs, likely a consequence of the cohesive clay material that dominates the channel bed and banks. A deep inner channel reflects the cohesive nature of the clay and the mechanisms of abrasion, and indicates that sediment load is low relative to the transport capacity of the flow. Unfortunately, weirs were problematic in this system because of the cohesive clay substrate, limited sediment supply, and low channel gradient. Although deeper flows due to backwaters might be more favorable for resident trout, less gravel and fewer riffles are likely to negatively impact trout spawning habitat, macroinvertebrate communities, and biofilm productivity. Our results demonstrate the potential limitations of a single-feature approach to restoration that may be ineffective for a given geomorphic context and may overlook other aspects of the ecosystem. We highlight the need to incorporate geomorphic characteristics of a system into project design and predictions of system response.

  16. Fine-grained sediment storage conditioned by Large Woody Debris in a gravel-bed river

    NASA Astrophysics Data System (ADS)

    Skalak, K. J.; Narinesingh, P.; Pizzuto, J. E.

    2006-05-01

    The purposes of this study are 1) to determine the quantity of mud and sand stored in the channel margins and near-bank regions of South River, a steep gravel-bedded stream in western Virginia, and 2) to understand the geomorphic and hydrologic processes that control the erosion and deposition of these fine-grained deposits. The volume of storage in these deposits is equivalent to about 5-10 percent of the river's annual suspended sediment load. Sediment storage in the near-bank regions is a result of reduced velocity caused by the bank obstructions. Storage occurs in four different geomorphic settings: 1) long pooled sections caused by bedrock or old mill dams, 2) regions downstream of riffles in channel margins with LWD accumulations, 3) bank obstructions usually caused by trees, 4) side channel backwaters where flow separates around islands. Most storage occurs in regions downstream of riffles (approximately 44 percent of the total). Long pooled sections account for roughly 37 percent of the total storage, bank obstructions account for 13 percent, and backwaters account for roughly 6 percent. In approximately 17 km of river, there are 38 separate fine-grained deposits (total volume more than 1600 m3). On average, these deposits are about 35 cm deep, 20 m long, and 4 m wide. They average 30 percent mud, 68 percent sand, and 2 percent gravel. These deposits have been cored and analyzed for Hg, grain size, loss-on-ignition, and bomb radiocarbon. High Hg concentrations in fish tissue are an ongoing problem along South River, further motivating detailed study of these deposits.

  17. Positive and negative impacts of five Austrian gravel pit lakes on groundwater quality.

    PubMed

    Muellegger, Christian; Weilhartner, Andreas; Battin, Tom J; Hofmann, Thilo

    2013-01-15

    Groundwater-fed gravel pit lakes (GPLs) affect the biological, organic, and inorganic parameters of inflowing groundwater through combined effects of bank filtration at the inflow, reactions within the lake, and bank filtration at the outflow. GPLs result from wet dredging for sand and gravel and may conflict with groundwater protection programs by removing the protective soil cover and exposing groundwater to the atmosphere. We have investigated the impact on groundwater of five GPLs with different sizes, ages, and mean residence times, and all having low post-excavation anthropogenic usage. The results revealed highly active biological systems within the lake water, in which primary producers significantly reduced inflowing nitrate concentrations. Decalcification also occurred in lake water, reducing water hardness, which could be beneficial for waterworks in hard groundwater areas. Downgradient groundwater nitrate and calcium concentrations were found to be stable, with only minor seasonal variations. Biological degradation of organic material and organic micropollutants was also observed in the GPLs. For young GPLs adequate sediment deposits may not yet have formed and degradation processes at the outflow may consequently not yet be well established. However, our results showed that within 5 years from the cessation of excavation a protective sediment layer is established that is sufficient to prevent the export of dissolved organic carbon to downgradient groundwater. GPLs can improve groundwater quality in anthropogenically (e.g., pesticides and nitrate) or geologically (e.g., hardness) challenging situations. However, post-excavation usage of GPLs is often dominated by human activities such as recreational activities, water sports, or fish farming. These activities will affect lake and groundwater quality and the risks involved are difficult to predict and monitor and can lead to overall negative impacts on groundwater quality. Copyright © 2012 Elsevier B

  18. A wireline piston core barrel for sampling cohesionless sand and gravel below the water table

    USGS Publications Warehouse

    Zapico, Michael M.; Vales, Samuel; Cherry, John A.

    1987-01-01

    A coring device has been developed to obtain long and minimally disturbed samples of saturated cohesionless sand and gravel. The coring device, which includes a wireline and piston, was developed specifically for use during hollow-stem auger drilling but it also offers possibilities for cable tool and rotary drilling. The core barrel consists of an inner liner made of inexpensive aluminum or plastic tubing, a piston for core recovery, and an exterior steel housing that protects the liner when the core barrel is driven into the aquifer. The core barrel, which is approximately 1.6m (5.6 feet) long, is advanced ahead of the lead auger by hammering at the surface on drill rods that are attached to the core barrel. After the sampler has been driven 1.5m (5 feet), the drill rods are detached and a wireline is used to hoist the core barrel, with the sample contained in the aluminum or plastic liner, to the surface. A vacuum developed by the piston during the coring operation provides good recovery of both the sediment and aquifer fluids contained in the sediment. In the field the sample tubes can be easily split along their length for on-site inspection or they can be capped with the pore water fluids inside and transported to the laboratory. The cores are 5cm (2 inches) in diameter by 1.5m (5 feet) long. Core acquisition to depths of 35m (115 feet), with a recovery greater than 90 percent, has become routine in University of Waterloo aquifer studies. A large diameter (12.7cm [5 inch]) version has also been used successfully. Nearly continuous sample sequences from sand and gravel aquifers have been obtained for studies of sedimentology, hydraulic conductivity, hydrogeochemistry and microbiology.

  19. Effect of replacing surface inlets with blind or gravel inlets on sediment and phosphorus subsurface drainage losses

    USDA-ARS?s Scientific Manuscript database

    Open surface inlets that connect to subsurface tile drainage systems provide a direct pathway for sediment, nutrients, and agrochemicals to surface waters. This study was conducted to determine whether modifying open inlets by burying them in gravel capped with 30 cm of sandy clay loam soil or in ve...

  20. Bed stability in unconfined gravel bed mountain streams: With implications for salmon spawning viability in future climates

    Treesearch

    Jim McKean; Daniele Tonina

    2013-01-01

    Incubating eggs of autumn-spawning Chinook salmon (Oncorhynchus tshawytscha) could be at risk of midwinter high flows and substrate scour in a changing climate. A high-spatial-resolution multidimensional hydrodynamics model was used to assess the degree of scour risk in low-gradient unconfined gravel bed channels that are the favored environment for autumn-spawning...

  1. To mulch or not to mulch? Effects of gravel mulch toppings on plant establishment and development in ornamental prairie plantings.

    PubMed

    Schmithals, Anja; Kühn, Norbert

    2017-01-01

    In recent years, North American prairie vegetation has served as a design model for highly attractive, low-cost and low-maintenance plantings in German urban green spaces. Where mixed-planting techniques, gravel mulch toppings and non-selective maintenance techniques such as mowing are used, prairie plantings are considered to be cost-effective alternative design concepts for public green space management. In this study, we investigated the establishment success of different mixtures of prairie species plantings on two sites with different soil conditions: topsoil and topsoil with graywacke gravel topping. We documented significantly higher average mortality rates on gravel mulch sites in the first year after establishment. Further development of mortality was not significantly different between sites. Weed species were always more numerous on topsoil sites and had an obvious effect on the visual impact of the plantings. The mulch created an effective barrier for wind-dispersed germinators. Soil temperatures down to 30 cm were significantly higher on gravel mulch sites throughout the year, stimulating more vital plant growth and a prolonged growing season. Our results emphasize the importance of considering these kinds of practical issues during the planning process as they are critical to the success or failure of the design.

  2. Fine gravel controls hydrologic and erodibility responses to trampling disturbance for coarse-textured soils with weak cyanobacterial crusts.

    USDA-ARS?s Scientific Manuscript database

    We compared short-term effects of lug-soled boot trampling disturbance on water infiltration and soil erodibility on coarse-textured soils covered by a mixture of fine gravel and coarse sand over weak cyanobacterially-dominated biological soil crusts. Trampling significantly reduced final infiltrati...

  3. Flow structure through pool-riffle sequences and a conceptual model for their sustainability in gravel-bed rivers

    Treesearch

    D. Caamano; P. Goodwin; J. M. Buffington

    2010-01-01

    Detailed field measurements and simulations of three-dimensional flow structure were used to develop a conceptual model to explain the sustainability of self-formed pool-riffle sequences in gravel-bed rivers. The analysis was conducted at the Red River Wildlife Management Area in Idaho, USA, and enabled characterization of the flow structure through two consecutive...

  4. Influence of hyporheic flow and geomorphology on temperature of a large, gravel-bed river, Clackamas River, Oregon, USA

    Treesearch

    Vol. 22 Hydrological Processes

    2008-01-01

    The hyporheic zone influences the thermal regime of rivers, buffering temperature by storing and releasing heat over a range of timesscales. We examined the relationship between hyporheic exchange and temperature along a 24-km reach of the lower Clackamas River, a large gravel-bed river in northwestern Oregon (median discharge = 75·7 m3/s;...

  5. Removal of Zn(II) from electroplating effluent using yeast biofilm formed on gravels: batch and column studies

    PubMed Central

    2014-01-01

    Background Present study deals with the removal of Zn(II) ions from effluent using yeast biofilm formed on gravels. Methods The biofilm forming ability of Candida rugosa and Cryptococcus laurentii was evaluated using XTT (2,3-bis[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide) reduction assay and monitored by scanning electron microscopy (SEM), and Confocal laser scanning microscopy (CLSM). Copious amount of extracellular polymeric substances (EPS) produced by yeast species was quantified and characterized by Fourier transform infrared spectroscopy (FT-IR). Results Yeast biofilm formed on gravels by C. rugosa and C. laurentii showed 88% and 74.2% removal of Zn(II) ions respectively in batch mode. In column mode, removal of Zn(II) ions from real effluent was found to be 95.29% by C. rugosa biofilm formed on gravels. Conclusion The results of the present study showed that there is a scope to develop a cost effective method for the efficient removal of Zn(II) from effluent using gravels coated with yeast biofilm. PMID:24397917

  6. Superfund Record of Decision (EPA Region 5): Wauconda Sand and Gravel, Wauconda, Illinois, September 1985. Final report

    SciTech Connect

    Not Available

    1985-09-30

    The Wauconda Sand and Gravel Landfill site is located in Lake County, Illinois, approximately two miles north of the Village of Wauconda. The 74-acre site is comprised of a 43-acre unpermitted landfill, a nine-acre permitted landfill, nine acres excavated but unfilled, and 13 acres of perimeter site area. Before 1950, the site property was used as a sand and gravel pit. From 1950 until 1977, Wauconda Sand and Gravel Company operated the northern portion (43 acres unpermitted fill) of the site as a landfill. Landfill operations during this period consisted of dumping refuse into the mined-out gravel pit. The refuse deposited at the landfill consisted of residential garbage, construction debris, some industrial sludges and drums with undetermined contents. In 1980, a private well adjacent to the eastern boundary of the landfill was sampled by Illinois Environmental Protection Agency and inorganic, organic and PCB contamination was detected. Additional investigations concluded that PCBs, metals, and organics were contaminating the ground water and surface water (Mutton Creek).

  7. Formation of gravel-mantled megaripples on Earth and Mars: Insights from the Argentinean Puna and wind tunnel experiments

    NASA Astrophysics Data System (ADS)

    Bridges, N. T.; Spagnuolo, M. G.; de Silva, S. L.; Zimbelman, J. R.; Neely, E. M.

    2015-06-01

    Pumice and lithic clasts from gravel-mantled megaripples in the Argentinean Puna, an analog to Martian large ripples and Transverse Aeolian Ridges (TARs), were put in a boundary layer wind tunnel to derive threshold speeds for various stages of motion of the component clasts and observe incipient bedform development. Combined with results from a field meteorological station, it is found that the gravel components can initially only move under gusty conditions, with the impact of saltating pumice and sand lowering threshold. Pumices can saltate without the impact of sand, implying that they are both an impelling force for other pumices and lithics, and are the most likely clast constituent to undergo transport. Accumulation into bedforms in the tunnel occurs when clasts self organize, with larger, more immobile particles holding others in place, a process that is accentuated in the field on local topographic highs of the undulating ignimbrite bedrock surface. In such an arrangement, pumices and especially lithics remain largely stable, with vibration the dominant mode of motion. This results in sand and silt entrapment and growth of the bedform through infiltration and uplift of the gravel. Resulting bedforms are gravel-mantled ripple-like forms cored with fine grained sediment. The Martian aeolian environment is similar to the Puna in terms of having grains of variable size, infrequent wind gusts, and saltating sand, implying that some TARs on the planet may have formed in a similar way.

  8. Hyporheic exchange in gravel bed rivers with pool-riffle morphology: Laboratory experiments and three-dimensional modeling

    Treesearch

    Daniele Tonina; John M. Buffington

    2007-01-01

    We report the first laboratory simulations of hyporheic exchange in gravel pool-riffle channels, which are characterized by coarse sediment, steep slopes, and three-dimensional bed forms that strongly influence surface flow. These channels are particularly important habitat for salmonids, many of which are currently at risk worldwide and which incubate their offspring...

  9. CHARACTERIZATION OF METAL ADSORPTION VARIABILITY IN A SAND & GRAVEL AQUIFER, CAPE COD, MASSACHUSETTS, U.S.A.

    EPA Science Inventory

    Several geochemical properties of an aquifer sediment that control metal-ion adsorption were investigated to determine their potential use as indicators of the spatial variability of metal adsorption. Over the length of a 4.5-m-long core from a sand and gravel aquifer, lead (Pb2+...

  10. CHARACTERIZATION OF METAL ADSORPTION VARIABILITY IN A SAND & GRAVEL AQUIFER, CAPE COD, MASSACHUSETTS, U.S.A.

    EPA Science Inventory

    Several geochemical properties of an aquifer sediment that control metal-ion adsorption were investigated to determine their potential use as indicators of the spatial variability of metal adsorption. Over the length of a 4.5-m-long core from a sand and gravel aquifer, lead (Pb2+...

  11. To mulch or not to mulch? Effects of gravel mulch toppings on plant establishment and development in ornamental prairie plantings

    PubMed Central

    Kühn, Norbert

    2017-01-01

    In recent years, North American prairie vegetation has served as a design model for highly attractive, low-cost and low-maintenance plantings in German urban green spaces. Where mixed-planting techniques, gravel mulch toppings and non-selective maintenance techniques such as mowing are used, prairie plantings are considered to be cost-effective alternative design concepts for public green space management. In this study, we investigated the establishment success of different mixtures of prairie species plantings on two sites with different soil conditions: topsoil and topsoil with graywacke gravel topping. We documented significantly higher average mortality rates on gravel mulch sites in the first year after establishment. Further development of mortality was not significantly different between sites. Weed species were always more numerous on topsoil sites and had an obvious effect on the visual impact of the plantings. The mulch created an effective barrier for wind-dispersed germinators. Soil temperatures down to 30 cm were significantly higher on gravel mulch sites throughout the year, stimulating more vital plant growth and a prolonged growing season. Our results emphasize the importance of considering these kinds of practical issues during the planning process as they are critical to the success or failure of the design. PMID:28166269

  12. Quantifying Channel Maintenance Instream Flows: An Approach for Gravel-Bed Streams in the Western United States

    Treesearch

    Larry J. Schmidt; John P. Potyondy

    2004-01-01

    This paper discusses one approach for quantifying channel maintenance instream flow necessary to achieve the Forest Service Organic Act purpose of securing favorable conditions of water flows. The approach is appropriate for quantifying channel maintenance flows on perennial, unregulated, snowmelt-dominated, gravel-bed streams with alluvial reaches. The approach...

  13. Can rapid assessment protocols be used to judge sediment impairment in gravel-bed streams? A commentary

    Treesearch

    Thomas E. Lisle; John M. Buffington; Peter R. Wilcock; Kristin Bunte

    2015-01-01

    Land management agencies commonly use rapid assessments to evaluate the impairment of gravel-bed streams by sediment inputs from anthropogenic sources. We question whether rapid assessment can be used to reliably judge sediment impairment at a site or in a region. Beyond the challenges of repeatable and accurate sampling, we argue that a single metric or protocol is...

  14. Fugitive dust emission source profiles and assessment of selected control strategies for particulate matter at gravel processing sites in Taiwan.

    PubMed

    Chang, Chang-Tang; Chang, Yu-Min; Lin, Wen-Yinn; Wu, Ming-Ching

    2010-10-01

    Particles emitted from gravel processing sites are one contributor to worsening air quality in Taiwan. Major pollution sources at gravel processing sites include gravel and sand piles, unpaved roads, material crushers, and bare ground. This study analyzed fugitive dust emission characteristics at each pollution source using several types of particle samplers, including total suspended particulates (TSP), suspended particulate (PM10), fine suspended particulate (PM2.5), particulate sizer, and dust-fall collectors. Furthermore, silt content and moisture in the gravel were measured to develop particulate emission factors. The results showed that TSP (< 100 microm) concentrations at the boundary of gravel sites ranged from 280 to 1290 microg/m3, which clearly exceeds the Taiwan hourly air quality standard of 500 microg/m3. Moreover, PM10 concentrations, ranging from 135 to 550 microg/m3, were also above the daily air quality standard of 125 microg/m3 and approximately 1.2 and 1.5 times the PM2.5 concentrations, ranging from 105 to 470 microg/m3. The size distribution analysis reveals that mass mean diameter and geometric standard deviation ranged from 3.2 to 5.7 microm and from 2.82 to 5.51, respectively. In this study, spraying surfactant was the most effective control strategy to abate windblown dust from unpaved roads, having a control efficiency of approximately 93%, which is significantly higher than using paved road strategies with a control efficiency of approximately 45%. For paved roads, wet suppression provided the best dust control efficiencies ranging from 50 to 83%. Re-vegetation of disturbed ground had dust control efficiencies ranging from 48 to 64%.

  15. Sedimentology and depositional history of Neogene gravel deposits in lower Tornillo Creek area of Big Bend National Park, Texas

    SciTech Connect

    Thurwachter, J.E.

    1984-04-01

    Neogene gravel deposits in the lower Tornillo Creek area of Big Bend National Park, Texas, record the filling of a small structural basin formed during Basin and Range tectonism. Four lithofacies are recognized in the Late Miocene La Noria member (informal name): (1) a medial braided-stream lithofacies consisting of upward-fining packages of cross-bedded gravel, sandstone, and siltstone; (2) a distal braided-stream lithofacies consisting of poorly-defined upward-fining packages of fine gravel, sandstone, and mudstone; (3) a calcrete-rich gravel and sandstone lithofacies representing strike-valley and alluvial-fan deposition, and (4) and ephemeral lake-plain lithofacies consisting of massive and burrowed mudstones with sheet-like sandstone interbeds. Upward-fining packages in the braided-stream lithofacies represent the lateral migration and avulsion of the stream tract across the basin; together with the strike-valley and alluvial-fan deposits, these record the initial stages of basin filling. Provenance studies show that much of this sediment was derived from northern Mexico. Overlying ephemeral-lake deposits record the structural tilting and closing of the downstream (north) end of the basin. Gravels and minor sandstones of the Pleistocene Estufa member (informal name) represent basinward progradation of alluvial fans. Deposition of the Estufa member resulted from: (1) Quaternary tectonic activity in the Chisos Mountains area; (2) lowering of local base level by post-Miocene development of the Rio Grande drainage through the area; and (3) Pleistocene pluvial-period climatic changes. Subsequent Quaternary faulting has caused minor deformation of the deposits.

  16. Sedimentology and depositional history of Neogene gravel deposits in lower Tornillo Creek area of Big Bend National Park, Texas

    SciTech Connect

    Thurwachter, J.E.

    1984-04-01

    Neogene gravel deposits in the lower Tornillo Creek area of Big Bend National Park, Texas, record the filling of a small structural basin formed during Basin and Range tectonism. Four lithofacies are recognized in the Late Miocene La Noria member (informal name): (1) a medial braided-stream lithofacies consisting of upward-fining packages of cross-bedded gravel, sandstone, and siltstone; (2) a distal braided-stream lithofacies consisting of poorly-defined upward-fining packages of fine gravel, sandstone, and mudstone; (3) a calcrete-rich gravel and sandstone lithofacies representing strike-valley and alluvial-fan deposition, and (4) and ephemeral lake-plain lithofacies consisting of massive and burrowed mudstones with sheet-like sandstone interbeds. Upward-fining packages in the braided-stream lithofacies represent the lateral migration and avulsion of the stream tract across the basin; together with the strike-valley and alluvial-fan deposits, these record the initial stages of basin filling. Provenance studies show that much of this sediment was derived from northern Mexico. Overlying ephemeral-lake deposits record the structural tilting and closing of the downstream (north) end of the basin. Gravels and minor sandstones of the Pleistocene Estufa member (informal name) represent basinward progradation of alluvial fans. Deposition of the Estufa member resulted from: (1) Quaternary tectonic activity in the Chisos Mountains area; (2) lowering of local base level by post-Miocene development of the Rio Grande drainage through the area; and (3) Pleistocene pluvial-period climatic changes. Subsequent Quaternary faulting has caused minor deformation of the deposits.

  17. A model to predict the evolution of a gravel bed river under an imposed cyclic hydrograph and its application to the Trinity River

    NASA Astrophysics Data System (ADS)

    Viparelli, Enrica; Gaeuman, David; Wilcock, Peter; Parker, Gary

    2011-02-01

    Major changes in the morphology of the Trinity River in California, such as narrowing of the cross section and sedimentation of fine sediment in pools, occurred after the closure of a system of dams. These changes caused a dramatic reduction in the salmonid population and a resulting decline of the fishery. Gravel augmentation, regulated flood releases, and mechanical channel rehabilitation are currently being implemented to help restore the aquatic habitat of the river. The present paper describes a tool, named the Spawning Gravel Refresher, for designing and predicting the effects of gravel augmentation in gravel bed rivers. The tool assumes an imposed, cycled hydrograph. The model is calibrated and applied to the regulated reach of the Trinity River in four steps: (1) zeroing runs to reproduce conditions of mobile bed equilibrium as best can be estimated for the predam Trinity River, (2) runs to compare the predictions with the results of previous studies, (3) runs at an engineering time scale to reproduce the effects of the dams, and (4) runs to design gravel augmentation schemes. In the fourth group of runs, the combined effects of engineered flood flow releases and gravel augmentation are predicted. At an engineering time scale, the model indicates that the fraction of fine sediment in the surface layer and in the topmost part of the substrate should decrease when subjected to these two restoration measures, with a consequent improvement of the quality of the spawning gravel.

  18. Using Pneumatics to Perform Laboratory Hydraulic Conductivity Tests on Gravel with Underdamped Responses

    NASA Astrophysics Data System (ADS)

    Judge, A. I.

    2011-12-01

    A permeameter has been designed and built to perform laboratory hydraulic conductivity tests on various kinds of gravel samples with hydraulic conductivity values ranging from 0.1 to 1 m/s. The tests are commenced by applying 200 Pa of pneumatic pressure to the free surface of the water column in a riser connected above a cylinder that holds large gravel specimens. This setup forms a permeameter specially designed for these tests which is placed in a barrel filled with water, which acts as a reservoir. The applied pressure depresses the free surface in the riser 2 cm until it is instantly released by opening a ball valve. The water then flows through the base of the cylinder and the specimen like a falling head test, but the water level oscillates about the static value. The water pressure and the applied air pressure in the riser are measured with vented pressure transducers at 100 Hz. The change in diameter lowers the damping frequency of the fluctuations of the water level in the riser, which allows for underdamped responses to be observed for all tests. The results of tests without this diameter change would otherwise be a series of critically damped responses with only one or two oscillations that dampen within seconds and cannot be evaluated with equations for the falling head test. The underdamped responses oscillate about the static value at about 1 Hz and are very sensitive to the hydraulic conductivity of all the soils tested. These fluctuations are also very sensitive to the inertia and friction in the permeameter that are calculated considering the geometry of the permeameter and verified experimentally. Several gravel specimens of various shapes and sizes are tested that show distinct differences in water level fluctuations. The friction of the system is determined by calibrating the model with the results of tests performed where the cylinder had no soil in it. The calculation of the inertia in the response of the water column for the typical testing

  19. Large Wood recruitment and transport along a piedmont gravel bed river

    NASA Astrophysics Data System (ADS)

    Picco, Lorenzo; Tonon, Alessia; Ravazzolo, Diego; Aristide Lenzi, Mario

    2015-04-01

    In recent years an increasing attention has been devoted on Large Wood (LW), focusing to its role and impact along riverine systems. However there is still a lack of knowledge about many aspects of its recruitment and displacement from the vegetated patches (e.g. floodplain and island) of a riverine environment. This research aims to analyse and consider the differences in LW recruitment during a flood event along a reach of a piedmont gravel bed river. The study has been carried out along a 3 km - long study reach located into the middle course of the gravel bed Piave River (North-Eastern Italian Alps). A buffer zone of 20 m - wide was considered along the floodplains and islands. Into this stripe every standing tree, with diameter ≥ 0.10 m, was measured manually (Diameter Breast Height-DBH; Height). Moreover, for each tree the GPS position was recorded and a numbered tag was installed to simplify the post event recovery. In November 2014 an over bankfull flood (Q=1039 m3 s-1; R.I=3.5 years) occurred. Preliminary results shows that 668 trees were recruited during the flood event thanks to both bank erosion processes along the floodplain banks and along the island shores. Analysing the origin, it is possible to define as 401 (60.03 %) trees were recruited from the floodplain, 244 (36.53%) from fluvial islands and, finally, 23 (3.44%) trees were not completely moved into the active channel area and recruited by the flood, but were just uprooted. Thanks to the accurate dendrometric measurements, it has been possible to define the dimensions for both category of LW, recruited from floodplain and island respectively. Looking to the minimum, maximum and mean height detected were defined values of 2.00, 20.00 and 8.98 m, and 2.20, 15.00 and 6.64 m, for floodplain and island, respectively. The DBH show minimum, maximum and mean values of about 0.10, 0.54 and 0.14 m, and 0.10, 0.44 and 0.14 m for floodplain and island, respectively. These dendrometric measurements

  20. Spatial characterization of hydraulic conductivity of perialpine alluvial gravel-and-sand aquifers

    NASA Astrophysics Data System (ADS)

    Diem, Samuel; Vogt, Tobias; Höhn, Eduard

    2010-05-01

    For many hydrogeological and modeling problems on a scale of the order of 10-100 m, an assessment of the spatial distribution of hydraulic conductivity is of great importance. This is one of the tasks of the RECORD project (Restored Corridor Dynamics) of CCES (Competence Center Environment and Sustainability of the ETH Domain). This project aims to understand, how river restoration measures affect river - river corridor - groundwater systems in hydrologic and ecologic terms. The river Thur and the alluvial gravel-and-sand aquifer of the perialpine Thur valley flood plain were chosen for field investigations. In this aquifer, the distribution of hydraulic conductivity at the required scale has not yet been investigated. Thus, the aim of this work is to assess the spatial distribution of hydraulic conductivity of the aquifer on a scale of the order of 10-100 m. To accomplish this, four methods were applied on different scales. Comparing the results of the different methods should lead to an optimization of future hydraulic investigations in alpine and perialpine alluvial gravel-and-sand aquifers. The different methods were applied at a test site in the central part of the valley (Widen, Felben-Wellhausen/TG), which was instrumented with a total of 18 piezometers, covering an approximately 10×20 m area (aquifer thickness, 7 m). The gravel samples of the pre-liminary core drillings were sieved and out of the grain size distributions hydraulic conductivity was calculated (decimeter scale). Further, work included the conduction and analysis of a pumping test (decameter scale), flowmeter logs and multilevel slug tests (meter scale) with appropriate methods. A statistical evaluation of the values of hydraulic conductivity from the above methods showed that the results are quite diverse. Thus, the choice of the method to assess the distribution of hydraulic conductivity has to be done according to the problem and the required level of detail. The following recommendations

  1. Estimation of recharge rates to the sand and gravel aquifer using environmental tritium, Nantucket Island, Massachusetts

    USGS Publications Warehouse

    Knott, Jayne Fifield; Olimpio, Julio C.

    1986-01-01

    Estimation of the average annual rate of ground-water recharge to sand and gravel aquifers using elevated tritium concentrations in ground water is an alternative to traditional steady-state and water-balance recharge-rate methods. The concept of the tritium tracer method is that the average annual rate of ground-water recharge over a period of time can be calculated from the depth of the peak tritium concentration in the aquifer. Assuming that ground-water flow is vertically downward and that aquifer properties are reasonably homogeneous, and knowing the date of maximum tritium concentration in precipitation and the current depth to the tritium peak from the water table, the average recharge rate can be calculated. The method, which is a direct-measurement technique, was applied at two sites on Nantucket Island, Massachusetts. At site 1, the average annual recharge rate between 1964 and 1983 was 26.1 inches per year, or 68 percent of the average annual precipitation, and the estimated uncertainty is ?15 percent. At site 2, the multilevel water samplers were not constructed deep enough to determine the peak concentration of tritium in ground water. The tritium profile at site 2 resembles the upper part of the tritium profile at site 1 and indicates that the average recharge rate was at least 16 .7 inches per year, or at least 44 percent of the average annual precipitation. The Nantucket tritium recharge rates clearly are higher than rates determined elsewhere in southeastern Massachusetts using the tritium, water-table-fluctuation, and water-balance (Thornthwaite) methods, regardless of the method or the area. Because the recharge potential on Nantucket is so high (runoff is only 2 percent of the total water balance), the tritium recharge rates probably represent the effective upper limit for ground-water recharge in this region. The recharge-rate values used by Guswa and LeBlanc (1985) and LeBlanc (1984) in their ground-water-flow computer models of Cape Cod are

  2. A procedure for classifying textural facies in gravel-bed rivers

    USGS Publications Warehouse

    Buffington, J.M.; Montgomery, D.R.

    1999-01-01

    Textural patches (i.e., grain-size facies) are commonly observed in gravel-bed channels and are of significance for both physical and biological processes at subreach scales. We present a general framework for classifying textural patches that allows modification for particular study goals, while maintaining a basic degree of standardization. Textures are classified using a two-tier system of ternary diagrams that identifies the relative abundance of major size classes and subcategories of the dominant size. An iterative procedure of visual identification and quantitative grain-size measurement is used. A field test of our classification indicates that it affords reasonable statistical discrimination of median grain size and variance of bed-surface textures. We also explore the compromise between classification simplicity and accuracy. We find that statistically meaningful textural discrimination requires use of both tiers of our classification. Furthermore, we find that simplified variants of the two-tier scheme are less accurate but may be more practical for field studies which do not require a high level of textural discrimination or detailed description of grain-size distributions. Facies maps provide a natural template for stratifying other physical and biological measurements and produce a retrievable and versatile database that can be used as a component of channel monitoring efforts.Textural patches (i.e., grain-size facies) are commonly observed in gravel-bed channels and are of significance for both physical and biological processes at subreach scales. We present a general framework for classifying textural patches that allows modification for particular study goals, while maintaining a basic degree of standardization. Textures are classified using a two-tier system of ternary diagrams that identifies the relative abundance of major size classes and subcategories of the dominant size. An iterative procedure of visual identification and quantitative grain

  3. The spatial distribution of microfabric around gravel grains: indicator of till formation processes

    NASA Astrophysics Data System (ADS)

    KalväNs, Andis; Saks, Tomas

    2010-05-01

    Till micromorphology studies in thin sections is an established tool in the field of glacial geology. Often the thin sections are inspected only visually with help of mineralogical microscope. This can lead to subjective interpretation of observed structures. More objective method used in till micromorphology is measurement of apparent microfabric, usually seen as preferred orientation of elongated sand grains. In theses studies only small fraction of elongated sand grains often confined to small area of thin section usually are measured. We present a method for automated measurement of almost all elongated sand grains across the full area of the thin section. Apparently elongated sand grains are measured using simple image analysis tools, the data are processed in a way similar to regular till fabric data and visualised as a grid of rose diagrams. The method allows to draw statistical information about spatial variation of microfabric preferred orientation and fabric strength with resolution as fine as 1 mm. Late Weichselian tills from several sites in Western Latvia were studied and large variations in fabric strength and spatial distribution were observed in macroscopically similar till units. The observed types of microfabric spatial distributions include strong, monomodal and uniform distribution; weak and highly variable in small distances distribution; consistently bimodal distribution and domain-like pattern of preferred sand grain orientation. We suggest that the method can be readily used to identify the basic deformation and sedimentation processes active during the final stages of till formation. It is understood that the microfabric orientation will be significant affected by nearby large particles. The till is highly heterogonous sediment and the source of microfabric perturbations observed in thin section might lie outside the section plane. Therefore we suggest that microfabric distribution around visible sources of perturbation - gravel grains cut

  4. Analysing hyporheic exchange processes during unsteady flow in a small gravel bed river

    NASA Astrophysics Data System (ADS)

    Kurtenbach, Andreas; Schuetz, Tobias; Krein, Andreas; Bierl, Reinhard

    2017-04-01

    Quantifying hyporheic exchange in gravel dominated rivers still remains a challenging task in stream ecology and hydrology, in particular during unsteady flow. We adopted three strategies to decipher exchange processes with the hyporheic zone during unsteady boundary conditions. First, artificial floods were generated in the mid-mountain gravel bed river system of the Olewiger Bach, Germany (24 km2). The advantage of the artificial flood approach lies in the selective control of governing processes by experimental design. Consequently, hydraulic boundary conditions such as maximum discharge, runoff volume and flood duration are steerable during the field experiments and the composition of the discharged water (e.g. low conductivity values) is known. Second, hyporheic exchange was analysed via heat dynamics using air, water and sediment pore water temperatures. Temperature dynamics in the hyporheic zone were monitored at the head, mid and tail of a riffle using specific lances (length: 67 cm, Ø: 3cm) containing temperature sensors in depths of 2, 5, 10, 15, 25, 45 and 65 cm. Short-term temperature variability during the unsteady artificial flood waves were analysed in high resolution of 10-30 seconds. In order to capture long-term seasonal fluctuations and dynamics during natural floods temperature was continuously measured at 5-min resolution. However, heat transfer in the hyporheic zone is affected by both advective and conductive transport. In a third strategy we therefore measure electrical conductivity and selected solutes in pore water during three artificial floods in 2015. Pore water was sampled from different sediment depths (5, 15, 25 and 45 cm) via stainless steel multilevel probes (length: 58 cm, Ø: 4cm). The investigation of temperature and pore water dynamics reveals that precedent hydrological conditions and ground-water levels are significant determinants for hyporheic exchange during unsteady flow. Stable groundwater stratification in spring for

  5. The impact of aquatic animals on bedload transport in gravel-bed rivers

    NASA Astrophysics Data System (ADS)

    Johnson, M.; Rice, S. P.

    2012-12-01

    Grain-scale processes are known to have large impacts on the transport of bed material in rivers. The structure, topography and distribution of grain sizes that make up a bed, all contribute to the mobility of fluvial substrates. Animals in rivers interact with the substrate in a multitude of ways, for example, when burrowing, moving and foraging for food. Alterations to the arrangement of grains that result from these activities have a demonstrable impact on particle stability and critical entrainment stresses. This raises the intriguing possibility that aquatic fauna have large, cumulative impacts on the structure of river bed material and, consequently, on the transport of bed material. The activities of signal crayfish (Pacifastacus leniusculus), a globally important invasive crustacean, alter the arrangement of surface grains in fluvial substrates. They also construct pits and mounds across surfaces within which they shelter. These structural and topographic alterations to surfaces were quantified using repeat laser scans to create Digital Elevation Models (DEMs) before and after crayfish activity. Crayfish moved grains up to 32 mm in diameter and with a submerged weight six times that of average adult crayfish. As a result of crayfish destroying grain-scale structures, 50% more material was entrained from disturbed fluvial substrates in comparison to control surfaces that had not been exposed to crayfish. Animals can also stabilise substrates. Hydropsychid caddisfly larvae bind grains together with silk, which is spun for a variety of purposes including the creation of nets to catch organic matter from the flow. Fine gravels (2-6 mm) that were colonised by natural densities of caddisfly, required 20% increases in shear stress to be mobilised in comparison to uncolonised, control gravels. Whilst these results demonstrate the potential for animals to affect grain-scale processes, their river-scale impact needs to be assessed in field environments, in the

  6. Identifying and Quantifying Sources of Fall Chinook Salmon Spawning Gravel to the Snake River in Hells Canyon

    NASA Astrophysics Data System (ADS)

    Welcker, C. W.; Burke, M.

    2015-12-01

    The Snake River in Hells Canyon supports a growing population of spawning Fall Chinook Salmon (Oncorhynchus tshawytscha) immediately downstream of the Hells Canyon Complex (HCC) of hydroelectric dams for the last 60 years. The long-term survival of this salmon run depends on the input of spawning gravel (25-150 mm) from local tributaries balancing the losses of spawning gravel through attrition and export out of the reach between the HCC and the Salmon River confluence. We are working to quantify the gravel input of these local tributaries at different time-scales and put this into the context of historical supply and transport. Long-term total sediment production rates of these tributaries estimated through various methods have varied by over 2 orders of magnitude, but we have recently completed 10Be work to constrain these estimates. We are measuring the change in storage of Fall Chinook spawning-size gravel through repeat multibeam echosounder surveys of the riverbed. The limited amount of repeat data collected to date has shown complex patterns of change in the riverbed. One possible driver of this complexity is the episodic and spatially variable nature of sediment inputs from these tributaries. We are attempting to quantify the frequency of the debris flows or floods capable of transporting spawning gravel through digitizing historic imagery of the last 60 years to determine the recurrence interval. We are measuring the magnitude of these events by surveying tributary fans pre and post-event to measure the sediment volume and particle size produced by specific events. These floods and debris flows are driven by extreme rainfall or snowmelt events, so we have also reconstructed historical meteorological conditions to identify the triggering conditions for transport, and identify the areas where snowmelt or rainfall is the more likely trigger. We are currently testing whether the unique bedrock geology of Hells Canyon can be used as a tracer to identify the

  7. Bayesian Analysis Of Stormwater Quality Treatment: Application To A Surface Sand Filter And A Subsurface Gravel Wetland

    NASA Astrophysics Data System (ADS)

    Avellaneda, P.; Ballestero, T. P.; Roseen, R.; Houle, J.; Linder, E.

    2010-12-01

    In a previous study of the same research project, Avellaneda et al. (2010) reported the application of a transport model for simulating contaminant removal by a sand filter. The model was based on the one-dimensional advection-dispersion equation. The unknown parameters of the model were the contaminant deposition rate and the hydrodynamic dispersion. The model was calibrated on a storm by storm basis and optimized parameter values were provided for 15 rainfall-runoff events. Although a statistical summary of optimized parameter values was provided, they recommended these results as input information for the implementation of a more rigorous statistical approach towards the description of parameter uncertainty. In this study, a Bayesian statistical approach is used to determine parameter uncertainty for the stormwater treatment model and monitoring data reported by Avellaneda et al. (2010). The objectives of this study are: (1) to develop a Bayesian stormwater quality approach for two stormwater treatment systems: a subsurface gravel wetland and a sand filter; (2) to determine the posterior probability distribution (PPD) of the deposition rate and the hydrodynamic dispersion; and (3) to perform Monte Carlo simulations to estimate effluent pollutant concentrations from the stormwater systems using the calculated PPDs. Two stormwater treatment systems were selected for this study: a sand filter and a subsurface gravel wetland. Both systems are located at the University of New Hampshire Stormwater Center in Durham, New Hampshire (USA). Influent and effluent for these two stormwater treatment systems were monitored between August 2004 and September 2006. A total of 15 storms were collected for the subsurface gravel wetland and 16 storms for the sand filter. Runoff constituent analysis included: TSS, TPH-D, and Zn. Results indicate that the mean particle deposition rate of the sand filter is higher than that of the subsurface gravel wetland. The deposition rate

  8. The impact of ellipsoidal particle shape on pebble breakage in gravel.

    PubMed

    Tuitz, Christoph; Exner, Ulrike; Frehner, Marcel; Grasemann, Bernhard

    2012-09-01

    We have studied the influence of particle shape and consequently loading configuration on the breakage load of fluvial pebbles. Unfortunately, physical strength tests on pebbles, i.e., point-load tests, can only be conducted under one specific stable loading configuration. Therefore, the physical uniaxial strength tests performed in this study were extended by a two-dimensional finite-element stress analysis, which is capable of investigating those scenarios that are not possible in physical tests. Breakage load, equivalent to that measured in unidirectional physical tests, was determined from the results of the stress analysis by a maximum tensile stress-based failure criterion. Using this assumption, allows the determination of breakage load for a range of different kind of synthetic loading configurations and its comparison with the natural breakage load distribution of the physical strength tests. The results of numerical modelling indicated that the configuration that required the least breakage load corresponded with the minor principal axis of the ellipsoidal pebbles. In addition, most of the simulated gravel-hosted loading configurations exceeded the natural breakage load distribution of fluvial pebbles obtained from the physical strength tests.

  9. Comparison of alternative remediation technologies for recycled gravel contaminated with heavy metals.

    PubMed

    Gao, Xiaofeng; Gu, Yilu; Huang, Sheng; Zhen, Guangyin; Deng, Guannan; Xie, Tian; Zhao, Youcai

    2015-11-01

    To evaluate the effects of different remediation methods on heavy metals contaminated recycled gravel, three immobilization agents (monopotassium phosphate, lime, nano-iron) and two mobilization agents (glyphosate, humic acid (HA)) were studied and compared. Results indicated that nano-iron powder was found to be more effective to immobilize Zn, Cu, Pb and Cd. Meanwhile, glyphosate presents a higher mobilization effect than HA with removal rates of about 66.7% for Cd, more than 80% for Cr, Cu and Zn, and the highest removal percentage of 85.9% for Cr. After the mobilization by glyphosate, the leaching rates of Zn, Cu and Cr were about 0.8%, and below 0.2% for Pb and Cd. The leaching rates after nano-iron powder treatment were 1.18% for Zn, 0.96% for Cr, 0.61% for Cu, 0.45% for Pb and Cd not detected. The formation and disappearance of metal (Zn/Cu/Cr/Pb/Cd) compounds were firmly confirmed through X-ray diffraction and scanning electron microscopy analyses on crystalline phases and morphological surface structures.

  10. Effects of HRT and water temperature on nitrogen removal in autotrophic gravel filter.

    PubMed

    Xu, Jing-hang; He, Sheng-bing; Wu, Su-qing; Huang, Jung-Chen; Zhou, Wei-li; Chen, Xue-chu

    2016-03-01

    Organic Carbon added to low ratio of carbon to nitrogen (C/N ratio) wastewater to enhance heterotrophic denitrification performance might lead to higher operating costs and secondary pollution. In this study, sodium thiosulfate (Na2S2O3) was applied as an electron donor for a gravel filter (one kind of constructed wetland) to investigate effects of hydraulic retention time (HRT) and water temperature on the nitrate removal efficiency. The results show that with an HRT of 12 h, the average total nitrogen (TN) removal efficiencies were 91% at 15-20 °C and 18% at 3-6 °C, respectively. When HRT increased to 24 h, the average TN removal increased accordingly to 41% at 3-6 °C, suggesting denitrification performance was improved by extended HRT at low water temperatures. Due to denitrification, 96% of added nitrate nitrogen (NO3(-)-N) was converted to nitrogen gas, with a mean flux of nitrous oxide (N2O) was 0.0268-0.1500 ug m(-2) h(-1), while 98.86% of thiosulfate was gradually converted to sulfate throughout the system. Thus, our results show that the sulfur driven autotrophic denitrification constructed wetland demonstrated an excellent removal efficiency of nitrate for wastewater treatment. The HRT and water temperature proved to be two influencing factors in this constructed wetland treatment system.

  11. Jejuia marina nov., isolated from gravel adjacent to Geommeolle beach on Udo Island, South Korea.

    PubMed

    Kim, Hyangmi; Yang, Jae-Hyung; Cha, Hyung-Kee; Lee, Jae-Bong; Suh, Seok-Jong; Bae, Kyung Sook; Park, Doo-Sang

    2015-11-01

    A bacterial strain, JH03(T), was isolated from gravel adjacent to Geommeolle beach on Udo Island, South Korea. The cells were Gram-stain-negative, aerobic, non-motile and rod shaped. The ranges of temperature, pH and NaCl concentration for growth of the bacterium were 10-45 °C, pH 6.0-9.5 and 0.5-5.0 % (w/v), respectively. The major fatty acids of the bacterium were iso-C(15:0) (15.4 %), iso-C(15:1) G (14.1 %), iso-C(16:0) 3-OH (14.1 %), iso-C(17:0) 3-OH (11.5 %) and anteiso-C(15:0) (11.3 %). The major isoprenoid quinone was MK-6. The polar lipids included phosphatidylethanolamine, two unidentified amino lipids and three unidentified lipids. The DNA G+C content was 34.2 mol%. The phylogenetic analysis of the 16S rRNA gene sequences showed that strain JH03(T) was most closely related to Jejuia pallidilutea EM39(T) (96.5 % sequence similarity). Based on the polyphasic analysis, strain JH03(T) is a novel species of the genus Jejuia, for which the name Jejuia marina sp. nov. is proposed. The type strain is JH03(T) (= KCTC 42342(T) = JCM 30601(T)).

  12. Hyunsoonleella udoensis sp. nov., isolated from a gravel sample from a beach of Udo island, Korea.

    PubMed

    Kim, Hyangmi; Lee, Jae-Bong; Oh, Hyun-Woo; Cha, Hyung-Kee; Yang, Jae-Hyung; Bae, Kyung Sook; Park, Doo-Sang

    2015-10-01

    A Gram-stain negative, non-motile, rod-shaped and aerobic bacterial strain, designated JG48(T), was isolated from a gravel sample taken from a beach adjacent to Udo island, South Korea. Strain JG48(T) was found to grow optimally at 25 °C, at pH 7.0-8.0 and in the presence of 2.0 % (w/v) NaCl. The 16S rRNA gene sequence of strain JG48(T) exhibited sequence similarities of 96.67 % to Hyunsoonleella jejuensis CNU004(T). The major fatty acids present in the strain JG48(T) were identified as iso-C15:0, iso-C15:1 G, iso-C17:0 3-OH and iso-C15:0 3-OH. The predominant isoprenoid quinone was identified as MK-6. The polar lipids profile of strain JG48(T) was found to consist of phosphatidylethanolamine, three unidentified amino lipids and four unidentified lipids. The DNA G+C content of strain JG48(T) was determined to be 34 mol%. Based on the morphological and physiological properties, and the results of phylogenetic analyses, the strain is considered to represent a novel species of the genus Hyunsoonleella, for which the name Hyunsoonleella udoensis sp. nov. is proposed. The type strain is JG48(T) (=KCTC 42341(T)=JCM 30600(T)).

  13. Efficacy of a vacuum benthos sampler for collecting demersal fish eggs from gravel substratum

    USGS Publications Warehouse

    Ruetz, C. R.; Jennings, C.A.

    1997-01-01

    We used two densities of eggs (low=900 eggs/m2; high=5100 eggs/m2) in laboratory experiments to estimate the recovery efficiency of the Brown benthos sampler for collecting fish eggs from gravel substrate and to determine if differences (e.g., 5-fold) in egg density in the substratum could be detected with the sampler. The mean egg recovery efficiency of the sampler in the low and high density treatments was 30% (SE=8.7) and 35% (SE=3.8), respectively. The difference between the treatment means was not significant. Therefore, data from the two treatments were pooled and used to estimate the recovery efficiency of the sampler (32.7%, SE=4.4). However, we were able to detect a 5?? difference in the number of eggs collected with the sampler between the two treatments. Our estimate of the recovery efficiency of the sampler for collecting fish eggs was less than those reported for the sampler's efficiency for collecting benthic macroinvertebrates. The low recovery efficiency of the sampler for collecting fish eggs does not lessen the utility of the device. Rather, ecologists planning to use the sampler must estimate the recovery efficiency of target fauna, especially if density estimates are to be calculated, because recovery efficiency probably is less than 100%. ?? Munksgaard, 1997.

  14. Development of channel organization and roughness following sediment pulses in single-thread, gravel bed rivers

    USGS Publications Warehouse

    Madej, Mary Ann

    2001-01-01

    Large, episodic inputs of coarse sediment (sediment pulses) in forested, mountain streams may result in changes in the size and arrangement of bed forms and in channel roughness. A conceptual model of channel organization delineates trajectories of response to sediment pulses for many types of gravel bed channels. Channels exhibited self-organizing behavior to various degrees based on channel gradient, presence of large in-channel wood or other forcing elements, the size of the sediment pulse, and the number of bed-mobilizing flows since disturbance. Typical channel changes following a sediment pulse were initial decreases in water depth, in variability of bed elevations, and in the regularity of bed form spacing. Trajectories of change subsequently showed increased average water depth, more variable and complex bed topography, and increased uniformity of bed form spacing. Bed form spacing in streams with abundant forcing elements developed at a shorter spatial scale (two to five channel widths) than in streams without such forcing mechanisms (five to 10 channel widths). Channel roughness increased as bed forms developed.

  15. The spatial characterization of turbulence around large roughness elements in a gravel-bed river

    NASA Astrophysics Data System (ADS)

    Lacey, R. W. Jay; Roy, André G.

    2008-12-01

    This study characterizes the flow field above and around multiple instream submerged cobbles, boulders, and pebble clusters in order to obtain a better understanding of the hydrodynamics associated with large roughness elements (LREs) in gravel-bed rivers. Spatially distributed high frequency, three-dimensional velocity measurements were recorded in situ using acoustic Doppler velocimeters at different flow stages. The spatial distributions of turbulent kinetic energy, ke, longitudinal component integral timescales, ITS u, and Reynolds shear stresses were characterized and are presented for selected sites. The longitudinal-vertical Reynolds shear stress increased with flow stage more strongly than the longitudinal-lateral or lateral-vertical Reynolds shear stresses and dominate at the highest measured flows. Canonical redundancy analysis was used to relate LRE morphometrics and mean flow conditions to the turbulence parameters estimated in the LRE wakes (i.e., ke, ITS u, and Reynolds shear stresses). LRE size and mean unobstructed velocity explained the highest proportion of the variance in the turbulent wake statistics. Multivariate regression models based on LRE width, mean unobstructed longitudinal velocity and flow depth are presented offering a tool to predict LRE wake turbulence.

  16. An Introduction to Using Surface Geophysics to Characterize Sand and Gravel Deposits

    USGS Publications Warehouse

    Lucius, Jeffrey E.; Langer, William H.; Ellefsen, Karl J.

    2007-01-01

    This report is an introduction to surface geophysical techniques that aggregate producers can use to characterize known deposits of sand and gravel. Five well-established and well-tested geophysical methods are presented: seismic refraction and reflection, resistivity, ground penetrating radar, time-domain electromagnetism, and frequency-domain electromagnetism. Depending on site conditions and the selected method(s), geophysical surveys can provide information concerning areal extent and thickness of the deposit, thickness of overburden, depth to the water table, critical geologic contacts, and location and correlation of geologic features. In addition, geophysical surveys can be conducted prior to intensive drilling to help locate auger or drill holes, reduce the number of drill holes required, calculate stripping ratios to help manage mining costs, and provide continuity between sampling sites to upgrade the confidence of reserve calculations from probable reserves to proved reserves. Perhaps the greatest value of geophysics to aggregate producers may be the speed of data acquisition, reduced overall costs, and improved subsurface characterization.

  17. An Introduction to Using Surface Geophysics to Characterize Sand and Gravel Deposits

    USGS Publications Warehouse

    Lucius, Jeffrey E.; Langer, William H.; Ellefsen, Karl J.

    2006-01-01

    This report is an introduction to surface geophysical techniques that aggregate producers can use to characterize known deposits of sand and gravel. Five well-established and well-tested geophysical methods are presented: seismic refraction and reflection, resistivity, ground penetrating radar, time-domain electromagnetism, and frequency-domain electromagnetism. Depending on site conditions and the selected method(s), geophysical surveys can provide information concerning aerial extent and thickness of the deposit, thickness of overburden, depth to the water table, critical geologic contacts, and location and correlation of geologic features. In addition, geophysical surveys can be conducted prior to intensive drilling to help locate auger or drill holes, reduce the number of drill holes required, calculate stripping ratios to help manage mining costs, and provide continuity between sampling sites to upgrade the confidence of reserve calculations from probable reserves to proved reserves. Perhaps the greatest value of geophysics to aggregate producers may be the speed of data acquisition, reduced overall costs, and improved subsurface characterization.

  18. Thermal modelling approaches to enable mitigation measures implementation for salmonid gravel stages in hydropeaking rivers

    NASA Astrophysics Data System (ADS)

    Casas-Mulet, R.; Alfredsen, K. T.

    2016-12-01

    The dewatering of salmon spawning redds can lead to early life stages mortality due to hydropeaking operations, with higher impact on the alevins stages as they have lower tolerance to dewatering than the eggs. Targeted flow-related mitigations measures can reduce such mortality, but it is essential to understand how hydropeaking change thermal regimes in rivers and may impact embryo development; only then optimal measures can be implemented at the right development stage. We present a set of experimental approaches and modelling tools for the estimation of hatch and swim-up dates based on water temperature data in the river Lundesokna (Norway). We identified critical periods for gravel-stages survival and through comparing hydropeaking vs unregulated thermal and hydrological regimes, we established potential flow-release measures to minimise mortality. Modelling outcomes were then used assess the cost-efficiency of each measure. The combinations of modelling tools used in this study were overall satisfactory and their application can be useful especially in systems where little field data is available. Targeted measures built on well-informed modelling approaches can be pre-tested based on their efficiency to mitigate dewatering effects vs. the hydropower system capacity to release or conserve water for power production. Overall, environmental flow releases targeting specific ecological objectives can provide better cost-effective options than conventional operational rules complying with general legislation.

  19. PGDP Trichloroethene Biodegradation Investigation Summary Report: Regional Gravel Aquifer & Northwest Plume

    SciTech Connect

    Hampson, Steve

    2008-09-01

    The evaluation of biological degradation processes addressed by this report are part of a broad trichloroethene (TCE) Fate and Transport Investigation that includes four (4) topics of phased investigation (Table ES1) relative to degradation and/or attenuation of TCE in the Regional Gravel Aquifer (RGA) underlying the United States Department of Energy Paducah Gaseous Diffusion Plant (PGDP). In order of implementation the project phases are: (1) derivation of a TCE first-order rate constant by normalization of TCE values against technetium-99 (99Tc) and chloride. 2) identification of the presence of microbes capable of aerobic co-metabolic TCE biodegradation using enzyme activity probes (this report); 3) Compound-specific isotope analysis (CSIA) to support prevalence of biotic and/or abiotic degradation processes; and 4) evaluation of potential abiotic RGA-TCE attenuation mechanisms including sorption. This report summarizes the Phase II activities related to the identification and evaluation of biological degradation processes that may be actively influencing TCE fate and transport in the RGA contaminant plumes at the United States Department of Energy (DOE) PGDP and its environs (Figure ES1). The goals of these activities were to identify active biological degradation mechanisms in the RGA through multiple lines of evidence and to provide DOE with recommendations for future TCE biological degradation investigations.

  20. Hydraulic controls of in-stream gravel bar hyporheic exchange and reactions

    NASA Astrophysics Data System (ADS)

    Trauth, Nico; Schmidt, Christian; Vieweg, Michael; Oswald, Sascha E.; Fleckenstein, Jan H.

    2015-04-01

    Hyporheic exchange transports solutes into the subsurface where they can undergo biogeochemical transformations, affecting fluvial water quality and ecology. A three-dimensional numerical model of a natural in-stream gravel bar (20 m × 6 m) is presented. Multiple steady state streamflow is simulated with a computational fluid dynamics code that is sequentially coupled to a reactive transport groundwater model via the hydraulic head distribution at the streambed. Ambient groundwater flow is considered by scenarios of neutral, gaining, and losing conditions. The transformation of oxygen, nitrate, and dissolved organic carbon by aerobic respiration and denitrification in the hyporheic zone are modeled, as is the denitrification of groundwater-borne nitrate when mixed with stream-sourced carbon. In contrast to fully submerged structures, hyporheic exchange flux decreases with increasing stream discharge, due to decreasing hydraulic head gradients across the partially submerged structure. Hyporheic residence time distributions are skewed in the log-space with medians of up to 8 h and shift to symmetric distributions with increasing level of submergence. Solute turnover is mainly controlled by residence times and the extent of the hyporheic exchange flow, which defines the potential reaction area. Although streamflow is the primary driver of hyporheic exchange, its impact on hyporheic exchange flux, residence times, and solute turnover is small, as these quantities exponentially decrease under losing and gaining conditions. Hence, highest reaction potential exists under neutral conditions, when the capacity for denitrification in the partially submerged structure can be orders of magnitude higher than in fully submerged structures.

  1. Hydrodynamics in a gravel beach and its impact on the Exxon Valdez oil

    NASA Astrophysics Data System (ADS)

    Guo, Qiaona; Li, Hailong; Boufadel, Michel C.; Sharifi, Youness

    2010-12-01

    This paper investigated the interaction of groundwater and seawater in a tidally influenced gravel beach. Field observations of water table, pore water salinity were performed. The two-dimensional finite element model MARUN was used to simulate observed water table and salinity. Based on field observations and model calibrations, a two-layered beach structure was identified which is characterized by a high-permeability surface layer underlain by a low-permeability lower layer. The salt wedge seaward of the low tide line was almost invariant in comparison with the strong fluctuations of the salinity plume in the surface layer of the intertidal zone. The presence of the two layers prevented the presence of a freshwater discharge "tube" between the upper saline plume and salt wedge. This is in contrast with the previous works where freshwater discharge tube was observed. The tide-induced submarine groundwater discharge (SGD) was estimated at 9 m3 d-1 m-1, a large value that is probably due to the large tidal range of ˜4.8 m and the very permeable surface layer. The freshwater-seawater dynamics revealed here may provide new insights into the complexity, intensity, and time scales of mixing between fresh groundwater and seawater in tidal beaches. The simulated water table of the beach was higher than the interface between the surface layer and the lower layer, which prevented Exxon Valdez oil from penetrating into the lower layer in 1989.

  2. Groundwater Flow and Solute Transport in a Tidally influenced gravel beach in Prince William Sound, Alaska

    NASA Astrophysics Data System (ADS)

    Bobo, A. M.; Boufadel, M. C.; Abdollahi Nasab, A.

    2009-12-01

    We investigated beach hydraulics in a gravel beach on Eleanor Island, Prince William Sound, Alaska that was previously polluted with the Exxon Valdez oil spill in 1989. The beach contains trace amounts of oil such that they don’t affect beach hydraulics. Measurements of water pressure and salinity were analyzed and simulated using the model SUTRA (Saturated-Unsaturated Groundwater Flow and Solute Transport). The results indicated that the beach consists of two layers with contrasting hydraulic properties: an upper layer with a hydraulic conductivity of 10-2 m/s, and a lower layer with a hydraulic conductivity of 10-5 m/s. The presence of the layer of low hydraulic conductivity constrained the fall of the water table resulting in a water table fluctuation that is almost independent of distance from the shoreline. This is unlike previous studies, which occurred in sandy beaches, and where the fluctuation decreased going landward. The water table remained above the layers’ interface, which suggests that the oil did not penetrate the lower layer. This could explain the presence of only tracer amount of oil in the beach. A sudden seaward increase of the slope of the two layers’ interface resulted in water leaving the lower layer near the mid-intertidal zone, and draining to the sea through the upper layer. This created the effect of a hydraulic rupture separating the hydraulics in the seaward portion of the beach from the rest of beach, especially at low tide.

  3. Geologie study off gravels of the Agua Fria River, Phoenix, AZ

    USGS Publications Warehouse

    Langer, W.H.; Dewitt, E.; Adams, D.T.; O'Briens, T.

    2010-01-01

    The annual consumption of sand and gravel aggregate in 2006 in the Phoenix, AZ metropolitan area was about 76 Mt (84 million st) (USGS, 2009), or about 18 t (20 st) per capita. Quaternary alluvial deposits in the modern stream channel of the Agua Fria River west of Phoenix are mined and processed to provide some of this aggregate to the greater Phoenix area. The Agua Fria drainage basin (Fig. 1) is characterized by rugged mountains with high elevations and steep stream gradients in the north, and by broad alluvial filled basins separated by elongated faultblock mountain ranges in the south. The Agua Fria River, the basin’s main drainage, flows south from Prescott, AZ and west of Phoenix to the Gila River. The Waddel Dam impounds Lake Pleasant and greatly limits the flow of the Agua Fria River south of the lake. The southern portion of the watershed, south of Lake Pleasant, opens out into a broad valley where the river flows through urban and agricultural lands to its confluence with the Gila River, a tributary of the Colorado River.

  4. Observations of event-based streambed deformation in a gravel bed channel

    NASA Astrophysics Data System (ADS)

    Haschenburger, Judith K.

    2006-11-01

    The streambed is the major source of bed load sediment in gravel bed channels and is necessarily deformed during floods that mobilize sediment. This study uses observations of scour and fill from Carnation Creek, Canada, to articulate at-a-point relations of the occurrence and magnitude of bed deformation and the resulting adjustments in bed configuration over a series of flood events. The likelihood of local bed deformation by scour, fill, or both depends on flow magnitude. At most locations, there is an imbalance of scour and fill that leads to adjustments in bed elevation, and these imbalances increase with flow. Persistent deformation of locations in lower portions of the bed topography tend to produce larger total exchanges between bed and mobile sediment over the flood series but locations that experience similar frequencies of bed deformation do not produce unique depth distributions. These results underscore the importance of understanding the coupling of scour and fill that produces streambed adjustment when modeling streambed evolution and managing river habitat.

  5. Modeling the changes in the concentration of aromatic hydrocarbons from an oil-coated gravel column

    NASA Astrophysics Data System (ADS)

    Jung, Jee-Hyun; Kang, Hyun-Joong; Kim, Moonkoo; Yim, Un Hyuk; An, Joon Geon; Shim, Won Joon; Kwon, Jung-Hwan

    2015-12-01

    The performance of a lab-scale flow-through exposure system designed for the evaluation of ecotoxicity due to oil spills was evaluated. The system simulates a spill event using an oil-coated gravel column through which filtered seawater is passed and flows into an aquarium containing fish embryos of olive flounder ( Paralichthys olivaceus) and spotted sea bass ( Lateolabrax maculates). The dissolved concentrations of individual polycyclic aromatic hydrocarbons (PAHs) in the column effluent were monitored and compared with theoretical solubilities predicted by Raoult's law. The effluent concentrations after 24 and 48 h were close to the theoretical predictions for the higher molecular weight PAHs, whereas the measured values for the lower molecular weight PAHs were lower than predicted. The ratios of the concentration of PAHs in flounder embryos to that in seawater were close to the lipid-water partition coefficients for the less hydrophobic PAHs, showing that equilibrium was attained between embryos and water. On the other hand, 48 h were insufficient to attain phase equilibrium for the more hydrophobic PAHs, indicating that the concentration in fish embryos may be lower than expected by equilibrium assumption. The results indicate that the equilibrium approach may be suitable for less hydrophobic PAHs, whereas it might overestimate the effects of more hydrophobic PAHs after oil spills because phase equilibrium in an oil-seawater-biota system is unlikely to be achieved. The ecotoxicological endpoints that were affected within a few days are likely to be influenced mainly by moderately hydrophobic components such as 3-ring PAHs.

  6. Sedimentation model of gravel-dominated alluvial piedmont fan, Ganga Plain, India

    NASA Astrophysics Data System (ADS)

    Shukla, U. K.

    2009-03-01

    The Piedmont Zone of the Indo-Gangetic Plain contains numerous, laterally coalescing small alluvial fans. The Latest Pleistocene-Holocene 30 km long Gaula Fan can be divided into gravelly proximal fan (0-14 km down-stream), gravel-sand rich mid fan (14-22 km) and sand-mud dominated distal fan (22-30 km). The fan succession is composed of two fan expansion cycles A and B. Separated by an undulatory erosional contact of regional extent, cycle A is characterized by river borne clast-supported gravelly deposits, and the overlying fan expansion cycle B by matrix-supported gravely debris flows. The main process behind fan development has been lateral migration of channels over the fan surface probably due to rapid sedimentation caused by increased sediment supply, and the fluctuating water budget in response to changing climate. The water laid expansion cycle A represents a humid phase. The debris flow deposits of expansion cycle B suggest a dry phase. Approximately between 8 and 3 Ka, cycle B also indicates a phase of tectonic instability in the Siwalik Hills forming the mountain front. The tectonic activity caused incision of rivers into the fan surface, and in turn resulted in reduced fan-building activity. At present the fan surface is accreting by sheet flow processes.

  7. Changes in woody debris and bed material texture in a gravel-bed channel

    NASA Astrophysics Data System (ADS)

    Haschenburger, Judith K.; Rice, Stephen P.

    2004-06-01

    This study investigated the response of bed material texture under two distinct periods of log jam conditions in a 900-m study reach of Carnation Creek, Vancouver Island, BC. A field program extending over seven flood seasons, coupled with existing streamflow records, channel maps, and low-altitude aerial photography, provides observations of jam stability and permeability, surface and subsurface grain-size, as well as bed material fluxes, sediment supply calibre, streambed stability, and sediment exchange near jams. All jams functioned as partial dams throughout the field program, but the overall perturbation of sediment transfers decreased when two jams were breached. Bed material texture exhibited the largest differences over the study reach during a period when log jams exerted a stronger influence over the passage of water and sediment. At individual gravel bars, most adjustments in surface and subsurface grain-size constituted less than a 20% change in percentile values. Larger changes occurred primarily in subsurface sediment. Temporal patterns in bed material texture exhibited variation between bars, but downstream of breached jams, surface sediment conformed to the expected fining trend, while the subsurface sediment increased in size. Surface and subsurface sediments evolved in the same direction only 64% of the time, and the different magnitudes of adjustment caused local armor ratios to vary over time. Results highlight that the temporal dynamism of large woody debris (LWD) should be coupled with spatial considerations for effective stream restoration and management of streambed sediment.

  8. Observations of gravel beach dynamics during high energy wave conditions using a laser scanner

    NASA Astrophysics Data System (ADS)

    Almeida, L. P.; Masselink, G.; Russell, P. E.; Davidson, M. A.

    2015-01-01

    A 2D laser-scanner was deployed at the high tide runup limit of a pure gravel beach (Loe Bar, Cornwall, England) to measure high-frequency (2.5 Hz) swash hydrodynamics and topographic changes during an energetic wave event. Measurements performed with the laser-scanner were corrected to compensate for levelling and orientation errors, and a variance threshold was applied to separate the beach topography from the water motions. Laser measurements were used to characterise the swash hydrodynamics and morphological changes during one tidal cycle through the calculation of several parameters, such as the 2% exceedence of the runup maxima (R2%), swash flow velocity skewness (< u3>), runup spectra and cumulative topographic changes. Results indicate that despite the small net morphological changes over the tide cycle, significant sediment mobilization occurs. A clear asymmetrical morphological response was found during the different tidal phases: the rising tide is dominated by accretion whilst the falling tide is dominated by erosion. The main factor controlling this asymmetrical morphological response is the step migration that, depending on the tide phase, controls the wave breaking point and consequently the dominant sediment transport direction. During the rising tide, step development decreases the shoreface slope and reduces the runup energy, whilst during the falling tide the step remobilization increases the shoreface slope and energy on the runup.

  9. Niche-partitioning of edaphic microbial communities in the Namib Desert gravel plain Fairy Circles.

    PubMed

    Ramond, Jean-Baptiste; Pienaar, Annelize; Armstrong, Alacia; Seely, Mary; Cowan, Don A

    2014-01-01

    Endemic to the Namib Desert, Fairy Circles (FCs) are vegetation-free circular patterns surrounded and delineated by grass species. Since first reported the 1970's, many theories have been proposed to explain their appearance, but none provide a fully satisfactory explanation of their origin(s) and/or causative agent(s). In this study, we have evaluated an early hypothesis stating that edaphic microorganisms could be involved in their formation and/or maintenance. Surface soils (0-5 cm) from three different zones (FC center, FC margin and external, grass-covered soils) of five independent FCs were collected in April 2013 in the Namib Desert gravel plains. T-RFLP fingerprinting of the bacterial (16S rRNA gene) and fungal (ITS region) communities, in parallel with two-way crossed ANOSIM, showed that FC communities were significantly different to those of external control vegetated soil and that each FC was also characterized by significantly different communities. Intra-FC communities (margin and centre) presented higher variability than the controls. Together, these results provide clear evidence that edaphic microorganisms are involved in the Namib Desert FC phenomenon. However, we are, as yet, unable to confirm whether bacteria and/or fungi communities are responsible for the appearance and development of FCs or are a general consequence of the presence of the grass-free circles.

  10. Removal of microbial pathogens in a sandy gravel aquifer under forced-gradient subsurface flow conditions

    NASA Astrophysics Data System (ADS)

    Oudega, Thomas James; Derx, Julia; van Driezum, Inge; Cisneros, Anibal; Sommer, Regina; Kirschner, Alexander; Farnleitner, Andreas; Blaschke, Alfred Paul

    2017-04-01

    Subsurface media are being used around the world as a means to mitigate microbial contamination, but vary widely in their ability to remove pathogens. To help to provide accurate risk assessments of microbial contamination of groundwaters, and establish safe setback distances between receiving waters and disposal fields, this study aims to use aquifer tracer tests to evaluate the ability of subsurface media to attenuate these pathogens. The novelty of this work is the use of a variety of different tracer substances (e.g. phages, spores, microspheres, conservative tracers) together in field experiments. This will be done by means of injecting these substances under a forced gradient in a sandy gravel aquifer in Lobau, Austria. The extraction of the tracers will be monitored in a pumping well at a distrance of 50m downgradient. This will be able to provide us with insight to the characteristics of microbial transport and how the microorganisms react to the subsurface in the study site. Subsequent numerical modelling of the experiments can tell us more about quantification of subsurface processes such as attachment/detachment, inactivation and die-off of these substances. The first field experiment with conservative tracers (NaCl) has been carried out in December 2016, and subsequent tests are being planned for the next months.

  11. Channel dynamics and habitat development in a meandering, gravel bed river

    NASA Astrophysics Data System (ADS)

    Harrison, L. R.; Legleiter, C. J.; Wydzga, M. A.; Dunne, T.

    2011-04-01

    We investigated how channel morphology, flow complexity, and habitat characteristics in a meandering gravel bed river evolved over time from a simple, reconfigured initial condition. Using a time series of topographic data, we measured rates of channel migration and morphologic change, documented patterns of sediment storage, and estimated rates of sediment supply. We constructed, calibrated, and validated hydrodynamic models to quantify how the evolving morphology influenced hydraulic conditions, flow complexity, and habitat suitability for Chinook salmon spawning and rearing. For a series of meander bends with constant curvature, similar bank materials, and an identical flow history, sediment supply and bar storage directly influenced channel migration rates. Habitat modeling indicated that the availability of Chinook salmon spawning habitat increased over time, whereas the majority of the reach continues to provide only low- to medium-quality rearing habitat for juvenile salmonids, primarily because of a lack of low-velocity refuge zones. However, other metrics of flow complexity indicate that areas of favorable flow conditions gradually expanded as point bars developed along the inner bank of each bend. These results indicate that although sediment supply can stimulate channel change and diversify river morphology, which acts to promote flow complexity and provide spawning habitat, these sediment-driven morphological changes might not create bioenergetically favorable habitat for juvenile salmonids.

  12. Biofilm growth in gravel bed streams controls solute residence time distributions

    NASA Astrophysics Data System (ADS)

    Aubeneau, A. F.; Hanrahan, Brittany; Bolster, Diogo; Tank, Jennifer

    2016-07-01

    Streambed substrates harbor a rich biome responsible for biogeochemical processing in riverine waters. Beyond their biological role, the presence of benthic and hyporheic biofilms can play an important role in influencing large-scale transport of solutes, even for conservative tracers. As biofilms grow and accumulate biomass, they actively interact with and influence surface and subsurface flow patterns. To explore this effect, we conducted experiments at the Notre Dame Linked Ecosystems Experimental Facility in four outdoor streams, each with different gravel beds. Over the course of 20 weeks we conducted transport experiments in each of these streams and observed different patterns in breakthrough curves as biofilms grew on the substrate. Biofilms played a major role in shaping the observed conservative transport patterns. Overall, while the presence of biofilms led to a decreased exchange rate between the fast (mobile) and slow (immobile) parts of the flow domain, water that was exchanged tended to be stored in the slow regions for longer times once biofilms had established. More specifically, we observed enhanced longitudinal dispersion in breakthrough curves as well as broader residence time distributions when biofilms were present. Biofilm colonization over time homogenized transport patterns across the four streams that were originally very distinct. These results indicate that stream biofilms exert a strong control on conservative solute transport in streams, a role that to date has not received enough attention.

  13. Measuring gravel transport and dispersion in a mountain river using passive radio tracers

    USGS Publications Warehouse

    Bradley, D. N.; Tucker, G. E.

    2012-01-01

    Random walk models of fluvial sediment transport recognize that grains move intermittently, with short duration steps separated by rests that are comparatively long. These models are built upon the probability distributions of the step length and the resting time. Motivated by these models, tracer experiments have attempted to measure directly the steps and rests of sediment grains in natural streams. This paper describes results from a large tracer experiment designed to test stochastic transport models. We used passive integrated transponder (PIT) tags to label 893 coarse gravel clasts and placed them in Halfmoon Creek, a small alpine stream near Leadville, Colorado, USA. The PIT tags allow us to locate and identify tracers without picking them up or digging them out of the streambed. They also enable us to find a very high percentage of our rocks, 98% after three years and 96% after the fourth year. We use the annual tracer displacement to test two stochastic transport models, the Einstein–Hubbell–Sayre (EHS) model and the Yang–Sayre gamma-exponential model (GEM). We find that the GEM is a better fit to the observations, particularly for slower moving tracers and suggest that the strength of the GEM is that the gamma distribution of step lengths approximates a compound Poisson distribution. Published in 2012. This article is a US Government work and is in the public domain in the USA.

  14. Sediment heterogeneity and mobility in the morphodynamic modelling of gravel-bed braided rivers

    NASA Astrophysics Data System (ADS)

    Singh, Umesh; Crosato, Alessandra; Giri, Sanjay; Hicks, Murray

    2017-06-01

    The effects of sediment heterogeneity and sediment mobility on the morphology of braided rivers are still poorly studied, especially when the partial sediment mobility occurs. Nevertheless, increasing the bed sediment heterogeneity by coarse sediment supply is becoming a common practice in river restoration projects and habitat improvement all over the world. This research provides a step forward in the identification of the effects of sediment sorting on the evolution of sediment bars and braiding geometry of gravel-bed rivers. A two-dimensional morphodynamic model was used to simulate the long-term developments of a hypothetical braided system with discharge regime and morphodynamic parameters derived from the Waimakariri River, New Zealand. Several scenarios, differing in bed sediment heterogeneity and sediment mobility, were considered. The results agree with the tendencies already identified in linear analyses and experimental studies, showing that a larger sediment heterogeneity increases the braiding indes and reduces the bars length and height. The analyses allowed identifying the applicability limits of uniform sediment and variable discharge modelling approaches.

  15. A new approach to define surface/sub-surface transition in gravel beds

    NASA Astrophysics Data System (ADS)

    Haynes, Heather; Ockelford, Anne-Marie; Vignaga, Elisa; Holmes, William

    2012-12-01

    The vertical structure of river beds varies temporally and spatially in response to hydraulic regime, sediment mobility, grain size distribution and faunal interaction. Implicit are changes to the active layer depth and bed porosity, both critical in describing processes such as armour layer development, surface-subsurface exchange processes and siltation/ sealing. Whilst measurements of the bed surface are increasingly informed by quantitative and spatial measurement techniques (e.g., laser displacement scanning), material opacity has precluded the full 3D bed structure analysis required to accurately define the surface-subsurface transition. To overcome this problem, this paper provides magnetic resonance imaging (MRI) data of vertical bed porosity profiles. Uniform and bimodal (σ g = 2.1) sand-gravel beds are considered following restructuring under sub-threshold flow durations of 60 and 960 minutes. MRI data are compared to traditional 2.5D laser displacement scans and six robust definitions of the surface-subsurface transition are provided; these form the focus of discussion.

  16. Water in sand and gravel deposits in McHenry County, Illinois

    SciTech Connect

    Nicholas, J.R.; Krohelski, J.T.

    1984-01-01

    Two general types of sand and gravel occur in McHenry County - unconfined aquifers, which are at or near the land surface, and semiconfined aquifers, which are overlain by one or more till members. Water levels in both types of aquifers are mapped from measurements made in the spring of 1979. The water-level configuration roughly parallels the land surface. Moraines and other topographically high features coincide with ground-water divides of local flow systems. Flow paths from divides to low-lands are relatively short - a few miles or less. Recharge predominates in uplands, whereas discharge predominates in lowlands. Water levels change seasonally in response to variations in recharge and discharge conditions. The highest water levels occur during spring and decline during the rest of the year. Ground water is of the calcium magnesium bicarbonate type and is of acceptable quality for most uses. However, for domestic and some industrial uses, treatment may be required to reduce hardness and to remove iron. Hardness ranged from 130 to 600 milligrams per liter as calcium carbonate, and dissolved iron concentrations ranges from less than 10 to 6200 micrograms per liter. The specific conductance of ground water ranged from 260 to 1170 micromhos per centimeter. Specific conductance exceeded 1000 micromhos per centimeter near Huntley and Hebron. Nitrate concentration was generally less than 0.68 milligrams per liter. 22 refs., 9 figs., 3 tabs.

  17. Heat as a tracer for examining depth-decaying permeability in gravel deposits.

    PubMed

    Sakata, Yoshitaka

    2015-04-01