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Sample records for gravels wad ghoweiba

  1. A research synthesis of therapeutic interventions for whiplash-associated disorder (WAD): Part 4 – noninvasive interventions for chronic WAD

    PubMed Central

    Teasell, Robert W; McClure, J Andrew; Walton, David; Pretty, Jason; Salter, Katherine; Meyer, Matthew; Sequeira, Keith; Death, Barry

    2010-01-01

    Whiplash-associated disorder (WAD) represents a significant public health problem, resulting in substantial social and economic costs throughout the industrialized world. While many treatments have been advocated for patients with WAD, scientific evidence supporting their effectiveness is often lacking. A systematic review was conducted to evaluate the strength of evidence for various WAD therapies. Multiple databases (including Web of Science, EMBASE and PubMed) were searched to identify all studies published from January 1980 through March 2009 that evaluated the effectiveness of any clearly defined treatment for acute (less than two weeks), subacute (two to 12 weeks) or chronic (longer than 12 weeks) WAD. The present article, the fourth in a five-part series, evaluates the evidence for noninvasive interventions initiated during the chronic phase of WAD. Twenty-two studies that met the inclusion criteria were identified, 12 of which were randomized controlled trials with ‘good’ overall methodological quality (median Physiotherapy Evidence Database score of 6). For the treatment of chronic WAD, there is evidence to suggest that exercise programs are effective in relieving whiplash-related pain, at least over the short term. While the majority of a subset of nine studies supported the effectiveness of interdisciplinary interventions, the two randomized controlled trials provided conflicting results. Finally, there was limited evidence, consisting of one supportive case series each, that both manual joint manipulation and myofeedback training may provide some benefit. Based on the available research, exercise programs were the most effective noninvasive treatment for patients with chronic WAD, although many questions remain regarding the relative effectiveness of various exercise regimens. PMID:21038010

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Course and Prognostic Factors for Neck Pain in Whiplash-Associated Disorders (WAD)

    PubMed Central

    Holm, Lena W.; Hogg-Johnson, Sheilah; Côté, Pierre; Cassidy, J. David; Haldeman, Scott; Nordin, Margareta; Hurwitz, Eric L.; Carragee, Eugene J.; van der Velde, Gabrielle; Peloso, Paul M.; Guzman, Jaime

    2008-01-01

    Study Design Best evidence synthesis. Objective To perform a best evidence synthesis on the course and prognostic factors for neck pain and its associated disorders in Grades I–III whiplash-associated disorders (WAD). Summary of Background Data Knowledge of the course of recovery of WAD guides expectations for recovery. Identifying prognostic factors assists in planning management and intervention strategies and effective compensation policies to decrease the burden of WAD. Methods The Bone and Joint Decade 2000–2010 Task Force on Neck Pain and its Associated Disorders (Neck Pain Task Force) conducted a critical review of the literature published between 1980 and 2006 to assemble the best evidence on neck pain and its associated disorders. Studies meeting criteria for scientific validity were included in a best evidence synthesis. Results We found 226 articles related to course and prognostic factors in neck pain and its associated disorders. After a critical review, 70 (31%) were accepted on scientific merit; 47 of these studies related to course and prognostic factors in WAD. The evidence suggests that approximately 50% of those with WAD will report neck pain symptoms 1 year after their injuries. Greater initial pain, more symptoms, and greater initial disability predicted slower recovery. Few factors related to the collision itself (for example, direction of the collision, headrest type) were prognostic; however, postinjury psychological factors such as passive coping style, depressed mood, and fear of movement were prognostic for slower or less complete recovery. There is also preliminary evidence that the prevailing compensation system is prognostic for recovery in WAD. Conclusion The Neck Pain Task Force undertook a best evidence synthesis to establish a baseline of the current best evidence on the course and prognosis for WAD. Recovery of WAD seems to be multifactorial.

  7. 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).

  8. 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.

  9. Unfolding with Maxed and Gravel.

    Energy Science and Technology Software Center (ESTSC)

    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 formore » “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.« less

  10. Lateral versus downstream transport of gravel in gravel-bed meandering rivers

    NASA Astrophysics Data System (ADS)

    Braudrick, C. A.; Dietrich, W. E.

    2014-12-01

    The degree to which gravel is exchanged laterally from eroding banks to point bars rather than transported downstream is largely unknown in gravel-bed meanders. This is crucial for understanding the potential effects bank stabilization on channel form. We use a compilation of field data to calculate the number of bends required for the supply of gravel from bank erosion to equal transport rate of gravel through a reach (Nb). A low value of Nb suggests that most of the gravel transport by the river is derived from local bank erosion and that, in essence, gravel is being shifted from outer bank to downstream bars with little net downslope flux. We compared the migration rate in 18 gravel-bed meanders rivers with calculations of the gravel transport capacity. Using the average bend length measured for the reach, and assuming the fraction of gravel in the banks ranged from 0.1 to 0.8 of the bank height, Nb was < 1 bend for 12 of the 18 rivers and generally < 10 bends for the remainder of the rivers. The meanders with Nb<1 had Shields stresses less than 0.044, which is the median Shields stress of 115 gravel-bed meanders in the literature. We compared these results to 9 gravel-bed meanders where gravel transport rates were available but the migration rates were unknown. For these rivers, we assumed migration rates ranged from 0.005-0.1 widths/yr (the range observed for gravel-bed meanders) and the gravel fraction in the banks ranged from 0.1-0.8. Nb was ranged from <1 to 20 bends, but was generally higher than for the gravel-bed meanders where we calculated the gravel transport capacity. This is not surprising because 7 of the 9 rivers had Shields stresses > 0.045, and higher gravel transport rates would be expected for this dataset. Our calculations suggest that for many gravel-bed meanders, gravel is being exchanged between the bed and banks within one bend, and even gravel-bed meanders with higher Shields stresses are likely exchanging gravel within a given reach

  11. 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

  12. Why do gravel bed rivers meander?

    NASA Astrophysics Data System (ADS)

    Braudrick, C. A.; Dietrich, W. E.

    2011-12-01

    Gravel bed meandering channels are common on Earth and have been observed on Mars, yet little is known about the conditions required to support meandering in gravel substrates. This is problematic for stream restoration projects that often redesign channels as gravel bed meanders without a complete recipe. We supplemented previous data compilations on channel morphology with additional data from the literature to investigate the conditions that support meandering in gravel bed rivers in the field. The 127 gravel bed rivers in our database are most common along the base of the Rocky Mountains in North America, and the United Kingdom. We identified the location of 111 of the reaches and using Google Earth, subdivided those channels into 3 categories: meandering channels with occasional islands (22 rivers), sinuous channels with bars but without evidence of cutoffs (36 rivers), and meandering channels with cutoffs (33 rivers). We also separately identified channels whose median diameter was less than 10 mm (20 rivers) because their behavior differed greatly from coarser rivers. We contrasted these rivers with sinuous gravel channels (channels without bars), braided gravel channels, and sand meanders from previous literature compilations. Coarse-grained (>10 mm) meanders with cutoffs have an average Shields stress of 0.032 and range from 0.016 to 0.046. This is significantly lower than the other gravel channel types where Shields stress can exceed 0.2 for both braided and sinuous channels. We propose that gravel meanders with cutoffs are not transporting gravel downstream, but rather are reworking gravel deposited under earlier hydrologic and sediment supply regimes. We observed similar behavior during meandering experiments, where coarse sediment was not transported around bends but was exchanged between channel banks and downstream bars. The low stresses on gravel meanders with cutoffs might also be expected to correspond with low stresses on the banks, which in

  13. Method of gravel packing a well

    SciTech Connect

    Almond, S. W.; Himes, R. E.

    1985-11-12

    The present invention relates to a thermally stable crosslinked gel gravel packing fluid for use in the treatment of highly deviated well bores penetrating a subterranean formation. The gravel packing fluid comprises an aqueous liquid, a gelling agent comprising a selected modified cellulose ether, a crosslinking agent, a breaker, a particulate agent and any additional additives that may be present.

  14. PREVALENCE AND RISK FACTORS OF ASTHMA AMONG WAD MEDANI BASIC SCHOOL CHILDREN, GEZIRA STATE, SUDAN

    PubMed Central

    Hussein, Salwa E.; Ahmed, Mohammed A.

    2005-01-01

    Objectives: Childhood asthma is said to be under-estimated and under-diagnosed in tropical countries including Sudan. The prevalence of asthma worldwide is increasing. The objective of this study was to determine the prevalence and the trigger factors of asthma among Wad Medani basic school children. Methods: A cross-sectional study was conducted during school year 2000-2001. The study group was selected by stratified proportional random sampling according to their age, sex and localities.Data was collected utilizing a pre-tested questionnaire addressing the history of asthma and its trigger factors (sample-2, 2002). Results: The results revealed that asthma is the ninth of the most common diseases among the school children, having a prevalence of 9.2% (sample 1) and 17.9% (sample 2), the main trigger factors of which are dust, cold bats, exercise and smoke respectively. Conclusion: Asthma among school children is a common problem that should be considered when planning preventive school health programmes. PMID:23012093

  15. 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. PMID:24927935

  16. 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

  17. Influence of gravel mulch stratum thickness and gravel grain size on evaporation resistance

    NASA Astrophysics Data System (ADS)

    Qiu, Yang; Xie, Zhongkui; Wang, Yajun; Ren, Jilong; Malhi, Sukhdev S.

    2014-11-01

    In the Loess Plateau of northwestern China, a system for dry farming has evolved based on the employ of gravel mulch. A couple of lab experiments were conducted to study the influences of mulch stratum thickness and gravel grain size on water vapor flow, with a focus on resistance to evaporation in gravel mulch stratum. In Experiment 1, six treatments included mulching with gravel of different thickness (2 cm, 4 cm, 6 cm, 8 cm and 10 cm) plus no mulching (control) were studied. In Experiment 2, the 10 cm thick mulch layer consisted of different grain size gravel [2-5 (A), 5-20 (B), 20-40 (C), 40-60 (D) and 60-80 (E) mm], plus three mixture treatments. Compared to bare soil, mulched soils had significantly lower accumulated evaporation, and gravel mulch significantly increased resistance to evaporation. The aerodynamic resistance to evaporation in bare soil is higher than that in mulched treatments and the relationship between equivalent grain size and aerodynamic resistance in mulched surface can be described by a line function. The relationships between mulch resistance and mulch stratum thickness or grain size of gravel, were represented by logistic curves. The findings showed that equivalent grain size and specific surface area of gravel were sensitive indicators of mulch resistance. Based on the results of laboratory experiments, we put forward a new calculated model of mulch resistance, but further research is needed for verification and exact parameterization of this model under field conditions.

  18. 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

  19. 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.

  20. 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.

  1. Erosion of sand from a gravel bed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  2. 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.

  3. Flow over gravel beds with clusters

    NASA Astrophysics Data System (ADS)

    Little, M.; Venditti, J. G.

    2014-12-01

    The structure of a gravel bed has been shown to alter the entrainment threshold. Structures such as clusters, reticulate stone cells and other discrete structures lock grains together, making it more difficult for them to be mobilized. These structures also generate form drag, reducing the shear stress available for mobilization. Form drag over gravel beds is often assumed to be negligible, but this assumption is not well supported. Here, we explore how cluster density and arrangement affect flow resistance and the flow structure over a fixed gravel bed in a flume experiment. Cluster density was varied from 6 to 68.3 clusters per square meter which corresponds to areal bed coverages of 2 to 17%. We used regular, irregular and random arrangements of the clusters. Our results show that flow resistance over a planar gravel bed initially declines, then increases with flow depth. The addition of clusters increases flow resistance, but the effect is dependent on cluster density, flow depth and arrangement. At the highest density, clusters can increase flow resistance as by as much as 8 times when compared to flat planar bed with no grain-related form drag. Spatially resolved observations of flow over the clusters indicate that a well-defined wake forms in the lee of each cluster. At low cluster density, the wakes are isolated and weak. As cluster density increases, the wakes become stronger. At the highest density, the wakes interact and the within cluster flow field detaches from the overlying flow. This generates a distinct shear layer at the height of the clusters. In spite of this change in the flow field at high density, our results suggest that flow resistance simply increases with cluster density. Our results suggest that the form drag associated with a gravel bed can be substantial and that it depends on the arrangement of the grains on the bed.

  4. The Flaxville gravel and its relation to other terrace gravels of the northern Great Plains

    USGS Publications Warehouse

    Collier, Arthur J.; Thom, W.T., Jr.

    1918-01-01

    In Nebraska and South Dakota there are widespread deposits of gravel and other material, largely superficial and generally uninitiated, known as the White River, Arikaree, Ogalalla, and other formations, which range in age from Oligocene to Pleistocene. West of these deposits, on the flanks of the Rocky Mountains, are several high plateaus covered with gravel, whose age, though not know, is generally regarded as Pleistocene.

  5. 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.

  6. Lessons from a Spawning Gravel Rehabilitation Program

    NASA Astrophysics Data System (ADS)

    Pasternack, G. B.; Wheaton, J. M.; Merz, J.

    2002-12-01

    Altered sediment and flow regimes in dammed and regulated rivers limit available spawning habitat to salmonids. River managers have attempted rehabilitation of spawning habitat with gravel augmentation and riffle construction projects, but often neglect well-established conceptual models of geomorphic and ecologic processes, let alone apply them in a predictive manner. Application of such models could not only improve rehabilitation projects, but also serve to further test and evaluate the underlying scientific theories against the rigors of real-world uncertainties. For the past two years a new science-based approach to rehabilitate spawning gravels for salmonids has been under development and testing to overcome these deficiencies. The approach includes a balance of science-based quantitative tools from multiple disciplines and qualitative local knowledge relevant to the region in which it has been applied. In 2001 and 2002 it was used to design and implement the placement of 907 and 2787 metric tons of gravel, respectively, on separate reaches of the lower Mokelumne River in Central California. A long-term monitoring program to quantify outcomes and assess sustainability is on-going. Lessons from these efforts are providing for adaptive management and will be presented.

  7. A fundamental procedure and calculation formula for evaluating gravel liquefaction

    NASA Astrophysics Data System (ADS)

    Yuan, Xiaoming; Cao, Zhenzhong

    2011-09-01

    Field investigations following the 2008 M s8.0 Wenchuan earthquake identified 118 liquefaction sites, most of which are underlain by gravelly sediment in the Chengdu Plain and adjacent Mianyang area, in the Sichuan Province. Gravel sediment in the Sichuan province is widely distributed; hence it is necessary to develop a method for prediction and evaluation of gravel liquefaction behavior. Based on liquefaction investigation data and in-situ testing, and with reference to existing procedures for sandy soil liquefaction evaluation, a fundamental procedure for gravel liquefaction evaluation using dynamic penetration tests (DPT) is proposed along with a corresponding model and calculation formula. The procedure contains two stages, i.e., pre-determination and re-determination. Pre-determination excludes impossible liquefiable or non-liquefiable soils, and re-determination explores a DPT-based critical N 120 blows calculation model. Pre-determination includes three criteria, i.e., geological age, gravel contents, gravel sediment depths and water tables. The re-determination model consists of five parameters, i.e., DPT reference values, gravel contents, gravel sediment depths, water tables and seismic intensities. A normalization method is used for DPT reference values and an optimization method is used for the gravel sediment depth coefficient and water table coefficient. The gravel liquefaction evaluation method proposed herein is simple and takes most influencing factors on gravel sediment liquefaction into account.

  8. Controls on the abruptness of gravel-sand transitions

    NASA Astrophysics Data System (ADS)

    Venditti, J. G.; Church, M. A.; Lamb, M. P.; Domarad, N.; Rennie, C. D.

    2014-12-01

    As gravel-bedded rivers fine downstream, they characteristically exhibit an abrupt transition from gravel- to sand-bed. This is the only abrupt transition in grain-size that occurs in the fluvial system and has attracted considerable attention. A number of competing theories have been proposed to account for the abruptness of the transition, including base-level control, attrition of ~10mm gravel to produce sand, and sediment sorting processes. The prevailing theory for the emergence of abrupt transitions is size selective sorting of bimodal sediment wherein gravel deposits due to downstream declining shear stress, fining the bedload until a sand-bed emerges. We explored this hypothesis by examining grain-size, shear stress, gravel mobility and sand suspension thresholds through the gravel-sand transition (GST) of the Fraser River, British Columbia. The Fraser GST is an arrested gravel wedge with patches of gravel downstream of the wedge forming a diffuse extension. There is an abrupt change in bed slope through the transition that leads to an abrupt change in shear stress. The GST, bed-slope change and backwater caused by the ocean are all coincident spatially, which enhances the sharpness of the GST. Interestingly, the bimodal reach of the river occurs downstream of the GST and exhibits no downstream gradients in shear stress, suspended sediment flux, gravel mobility or sand suspension thresholds. This calls into question the prevailing theory for the emergence of an abrupt GST by size selective sorting. We provide evidence, both empirical and theoretical, that suggests the emergence of an abrupt GST is caused by rapid deposition of sand when fine gravel deposits. We argue that the emergence of gravel-sand transitions is a consequence of gravel-bedded rivers adopting a steeper slope than sand-bedded rivers. The abruptness arises because the bed slope required to convey the gravel load fixes the distal location of a terminal gravel wedge, and once the river has

  9. 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

  10. 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.''

  11. Erosion depth of sand from an immobile gravel bed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  12. Can coarse surface layers in gravel-bedded rivers be mobilized by finer gravel bedload?

    NASA Astrophysics Data System (ADS)

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

    2005-12-01

    In response to reductions in sediment supply, gravel-bed rivers undergo a coarsening of the sediments that comprise the river's bed and, over some longer time scale, a river's grade may also be reduced as sediments are depleted from upstream reaches. Coarse, degraded river reaches are commonly observed downstream of dams across the Western United States. Following dam closure, these riverbeds become immobile under the altered flow and sediment supply regimes, leading to a reduction in the available salmon spawning and rearing habitat. Gravel augmentation to these streams is now common practice. This augmentation is typically seen as resurfacing the static coarse bed. As an alternative, we propose that the addition of appropriately finer gravels to these channels may be capable of mobilizing an otherwise immobile coarse surface layer, creating the potential to release fine material trapped beneath the surface. A series of laboratory experiments are being undertaken to test this hypothesis in a 30 m long and 0.86 m wide gravel-bedded flume channel using a constant discharge and a unimodal bed sediment with a median grain size of 8 mm and no sand present. The channel width-to-depth ratio of ~4 suppresses the development of lateral topography and allows us to focus on grain-to-grain interactions. Experiments proceed by maintaining a constant sediment feed until an equilibrium grade and transport rate are established, starving the flume of sediment for at least 24 hours, and then adding narrowly graded gravel over a period of one to two hours at a rate that is ~4x the bedload rate observed prior to terminating the sediment supply. The bed prior to sediment addition has an armor median grain size that is typically twice that of the subsurface and feed size distribution. The volume and median grain size of the resulting pulses are varied. Pulses move downstream rapidly with well-defined fronts in the form of bedload sheets and cause peaks in the sediment flux

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Quantification of Gravel Rural Road Sediment Production

    NASA Astrophysics Data System (ADS)

    Silliman, B. A.; Myers Toman, E.

    2014-12-01

    Unbound rural roads are thought to be one of the largest anthropogenic sources of sediment reaching stream channels in small watersheds. This sediment deposition can reduce water quality in the streams negatively impacting aquatic habitat as well as impacting municipal drinking water sources. These roads are thought to see an increase in construction and use in southeast Ohio due to the expansion of shale gas development in the region. This study set out to quantify the amount of sediment these rural roads are able to produce. A controlled rain event of 12.7 millimeters of rain over a half hour period was used to drive sediment production over a 0.03 kilometer section of gravel rural road. These 8 segments varied in many characteristics and produced from 2.0 to 8.4 kilograms of sediment per 0.03 kilometers of road with the average production over the 8 segments being 5.5 kilograms of sediment. Sediment production was not strongly correlated with road segment slope but traffic was found to increase sediment production from 1.1 to 3.9 times as much sediment after traffic use. These results will help inform watershed scale sediment budgeting, and inform best management practices for road maintenance and construction. This study also adds to the understanding of the impacts of rural road use and construction associated with the changing land use from agricultural to natural gas extraction.

  18. Predictive Design Morphologies for Gravel Augmentation

    NASA Astrophysics Data System (ADS)

    Brown, R. A.; Pasternack, G. B.

    2004-12-01

    Spawning habitat rehabilitation (SHR) is an interdisciplinary practice merging hydrology, geomorphology, aquatic ecology, and civil engineering to improve existing aquatic habitat and restoring fluvial complexity. Although SHR is widespread, it needs a science-based design process. The Spawning Habitat Integrated Rehabilitation Approach (SHIRA) is a scientifically peer-reviewed framework for doing SHR on regulated rivers. Although SHIRA has shown success with gravel augmentation on the Mokulmne River using hypothesis driven designs, the goal of this study was to evaluate several more natural processes for their potential in SHR, and to do so at the geomorphic-unit scale for the first time. Multiple design hypotheses were included in 6 SHR scenarios for rehabilitating the Lewiston Dam reach of the Trinity River, CA. Morphologies tested for their process mechanics included central bars, transverse-oblique bars, riffles, point bars, and bench-constricted pools. Varying longitudinal and lateral approach slopes for each feature were evaluated as well as feature sequencing. For each design scenario, a 2D model predicted local depth, velocity, shields stress, depth of scour, and habitat suitability for life stages of chinook and steelhead salmon at 300 and 6000 cfs. Data were analyzed to determine if conceptually expected geomorphic and ecological outcomes were in fact predicted by the 2D model. One design will be selected for actual construction in 2005 to evaluate 2D model predictions.

  19. 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

  20. RELATING WEIGHT AND COUNT DISTRIBUTIONS OF STREAM BED GRAVEL

    EPA Science Inventory

    The size distribution of particles in a stream bed reflects the stream hydrology as well as its physical and chemical water quality characteristics. In environmental assessments, gravel distribution determines habitat quality for aquatic insects and stream suitability for spawnin...

  1. 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

  2. Gravel-bed surface roughness from airborne laser scanning

    NASA Astrophysics Data System (ADS)

    Huang, G.; Wang, C.

    2011-12-01

    The roughness of gravel-bed surface is of great importance for fluvial geomorpholoy. Numerous studies have demonstrated that the fractal theory and the log-log variogram are useful for describing the multi-scaling behavior(grain scale and form scale) of the gravel-bed surface. In this study, we obtained the 3D surface information of the gravel surface of a central bar in Nan-Shih River, Taiwan using an airborne laser scanning with a nominal point density of 100 points/m2. The data were divided into 6m × 6m grids. The roughness characteristics of the gravel bar were discussed using the anisotropy axes (also called the directions of maximum and minimum continuity, respectively) determined from the variogram map for each grid. And, the fractal dimension of the two directions were also calculated.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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

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

    NASA Astrophysics Data System (ADS)

    Collie, Jeremy S.; Hermsen, Jerome M.; Valentine, Page C.

    2009-09-01

    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 m 2) 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

  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. 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.

  11. Incipient Motion and Particle Transport in Gravel - Streams

    NASA Astrophysics Data System (ADS)

    Matin, Habib

    The incipient motion of sediment particles in gravel-bed rivers is a very important process. It represents the difference between bed stability and bed mobility. A field study was conducted in Oak Creek, Oregon to investigate incipient motion of individual particles in gravel-bed streams. Investigation was also made of the incipient motion of individual gravel particles in the armor layer, using painted gravel placed on the bed of the stream and recovered after successive high flows. The effect of gravel particle shape was examined for a wide range of flow conditions to determine its significance on incipient motion. The result of analysis indicates a wide variation in particle shapes present. Incipient motion and general transport were found to be generally independent of particle shape regardless of particle sizes. A sample of bed material may contain a mixture of shapes such as well-rounded, oval, flat, disc-like, pencil-shaped, angular, and block-like. These are not likely to move in identical manners during transport nor to start motion at the same flow condition. This leads to questions about the role of shape in predicting incipient motion and equal mobility in gravel-bed streams. The study suggests that gravel particles initiate motion in a manner that is independent of particle shape. One explanation may be that for a natural bed surface many particles rest in orientations that give them the best protection against disturbance, probably a result of their coming to rest gradually during a period of decreasing flows, rather than being randomly dumped. But even when tracer particles were placed randomly in the bed surface there was no evident selectively for initiation of motion on the basis of particle shape. It can be concluded from analysis based on the methods of Parker et al. and Komar that there is room for both equal mobility and flow-competence evaluations. However, the equal mobility concept is best applied for conditions near incipient motion and

  12. 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

  13. 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.

  14. 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.

  15. 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...

  16. 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. 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...

  17. 40 CFR 436.30 - Applicability; description of the construction sand and gravel subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... processing of dredged sand and gravel which is subject to the provisions of 33 CFR part 230 of this chapter... 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...

  18. 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...

  19. 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...

  20. 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...

  1. 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...

  2. 40 CFR 436.30 - Applicability; description of the construction sand and gravel subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... processing of dredged sand and gravel which is subject to the provisions of 33 CFR part 230 of this chapter... 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...

  3. 40 CFR 436.30 - Applicability; description of the construction sand and gravel subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... and gravel which is subject to the provisions of 33 CFR part 230 of this chapter will not be governed... 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...

  4. 40 CFR 436.30 - Applicability; description of the construction sand and gravel subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... processing of dredged sand and gravel which is subject to the provisions of 33 CFR part 230 of this chapter... 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...

  5. 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...

  6. 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

  7. 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.

  8. Changes in Bar Morphology in an Aggrading Gravel Bed River

    NASA Astrophysics Data System (ADS)

    Hodge, R. A.

    2014-12-01

    The River Wharfe, UK, is an aggrading gravel bed river, with frequent gravel bars. Management of the river system requires information about the rate and processes of change occurring to the gravel storage within the bars. From a scientific perspective, there are questions about how bar morphology changes as bars are deposited and eroded in this single thread system, about the extent to which flow conditions drive morphological change, and about the extent to which morphological changes can be predicted. Morphological changes of ten bars along the River Wharfe are reported between early 2012 and late 2014. The bars span a 6 km long length of river, downstream of the point where the river emerges from a confined valley. The bars range in length from 25 to 135 m. Bar grain size decreases downstream as a consequence of strong downstream fining. Bar morphology was surveyed using Terrestrial Laser Scanning at four time periods between early 2012 and late 2014. Each bar was surveyed from at least two scan positions, and georeferenced using a network of permanent survey markers. After initial processing to register the point clouds and remove vegetation, the change detection algorithm M3C2 was used to identify areas of significant volumetric change. The measured morphological changes between 2012 and 2013 indicate predominantly depositional changes on the bars, with an overall downstream decrease in the volume of change. However, there are local variations superimposed on this pattern. The mechanisms by which the bars change vary between bars, and include downstream progression of an avalanche face and gravel sheet infilling of local hollows. The measured changes are compared to flow data over the study period to identify the extent to which they are driven by flow.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2009-06-01

    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

  14. 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.

  15. 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

  16. 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.

  17. 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

    2004-01-01

    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

  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. 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

  20. Injury experience in sand and gravel mining, 1989

    SciTech Connect

    Not Available

    1990-01-01

    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 1989. 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. 3 figs., 38 tabs.

  1. Injury experience in sand and gravel mining, 1992

    SciTech Connect

    Reich, R.B.; Hugler, E.C.

    1994-05-01

    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 1992. 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.

  2. EXPERIMENTAL STUDY ON SEDIMENT BEHAVIOR ON ALTERNATE GRAVEL-BARS

    NASA Astrophysics Data System (ADS)

    Mizoguchi, Atsuko

    These days, more information about the physical surface condition of riverbeds is needed for good river management to be able to take the habitat of river organisms into account. However, it is difficult to examine either sediment conditions at the surface or the substrate structure in detail because of problems in predicting sediment behavior in a real river. Furthermore, the attributes of mixed sediment transport vary depending on physical conditions, making it difficult to describe using numerical simulations. Therefore, a series of flume experiments were conducted in order to examine sediment behavior through alternate bars composed of sand and gravel. These experiments demonstrated the characteristics of fine and coarse sediment movement and indicated the plane distribution of sediment transport on the bars. Additionally, results indicated the impact of fine sediment supply on bed degradation, as well as on bar-morphology.

  3. 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 PMID:9175542

  4. 40 CFR 436.30 - Applicability; description of the construction sand and gravel subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... and gravel which is subject to the provisions of 33 CFR part 230 of this chapter will not be governed... 40 Protection of Environment 29 2010-07-01 2010-07-01 false Applicability; description of the construction sand and gravel subcategory. 436.30 Section 436.30 Protection of Environment...

  5. One-trip, multizone gravel-packing technique for low-pressure, shallow wells

    SciTech Connect

    Welrich, J.B.; Zaleski, T.E. Jr.; Tyler, S.L. )

    1990-11-01

    This paper describes a one-trip, multizone gravel-packing technique designed for use in short-zoned, shallow, low-pressure wells. The system, which allows several zones to be completed with a single gravel-pack assembly, has been adapted for use in both standard and thermal applications.

  6. 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.

  7. Neither the WAD-classification nor the Quebec Task Force follow-up regimen seems to be important for the outcome after a whiplash injury. A prospective study on 186 consecutive patients

    PubMed Central

    Kivioja, Jouko; Jensen, Irene

    2008-01-01

    A classification of injury and a follow-up schedule were proposed by the Quebec Task Force (QTF) in 1995. No general agreement about the clinical usefulness of the WAD-classification or of the suggested follow-up regimen exists. A series of 186 consecutive cases seen in the emergency room during the acute phase after a whiplash injury was prospectively studied for 1 year. All findings including history and physical findings were recorded using standardized QTF protocols. In one group follow-up visits were done according to the QTF regimen: at 1, 3, 6, 12 weeks and 1 year after the accident; in a control group no visit was scheduled. The outcome variable was neck pain at 1 year after the accident. After 1 year, 18% of the total number of patients had significant neck pain. Risk factors for chronic neck pain at 1 year after whiplash injury were: neck pain before the accident and a high degree of emotional distress at the time of the accident; both factors independently associated with a tenfold increased risk of developing chronic neck pain. Neither the WAD classification nor the QTF follow-up regimen could be linked to a better outcome. In this study the outcome was associated with patient-specific characteristics and not with physical signs of injury, the depth of the initial evaluation or the follow-up regimen. PMID:18427841

  8. Hydrogeophysics of gravel-dominated alluvial floodplains in eastern Oklahoma

    NASA Astrophysics Data System (ADS)

    Miller, Ronald B.

    Multi-electrode surface electrical resistivity (ERI) profiles of the floodplains show lenticular features with high resistivity within a domain of lower resistivity. Floodplain subsoil is composed of mixture of coarse and fine fractions (less than 0.25 mm). The proportion of the fine fraction from cores at the sites shows a negative power relationship with both resistivity (R2 = 0.85) and hydraulic conductivity (R 2 = 0.72), suggesting that the fine content is the major factor in the hydraulic and electrical behavior of the gravel subsoil. A linear relationship between hydraulic conductivity and resistivity is significant and the resulting equation Ksat = 0.11rho allows resistivity (rho) to be interpreted as saturated hydraulic conductivity (Ksat). The median hydraulic conductivity on all profiles from all sites was at least 20 m d-1, which is within the range for gravel soils. This high hydraulic conductivity suggests that at least half of the subsurface at each floodplain is likely to behave as a "high-flow domain" with the ability to conduct water at rates of 20 m d-1 or greater. Several ERI profiles at Barren Fork Creek (BFC) had high resistivity values that were significantly higher than the remaining ERI profiles at BFC and the other sites measured at the 84th percentile. Those ERI profiles were obtained from an area within the BFC study site where a trench injection test found a tracer (Rhodamine WT) to move in a manner that suggests preferential flow. A storm runoff pulse passed the BFC site over May 1-5, 2009 featuring 2.2 m of stage increase, which caused the water table to rise into the gravel-dominated vadose zone at the site. Water table maps, corresponding to the times when stream elevation matched the selected hydraulic conductivity elevations, were prepared from pressure transducers placed in monitoring wells at the site. It appeared that there was little attenuation of the energy of the storm pulse even at the furthest point in the study site: at

  9. Classification of Chilean gravel-bed rivers: a proposal

    NASA Astrophysics Data System (ADS)

    Iroumé, Andrés; Vergara, Gastón; Mao, Luca; Sandoval, Víctor

    2015-04-01

    Investigations on fluvial morphodynamics in Chilean rivers are still scarce, and up to date very little attempts have been made in order to generate a classification scheme. However, the latitudinal variation in vegetation and climatic conditions and the geography of the country offer an almost unique opportunity to study gravel-bed river variations with both latitude and extreme geophysical events. We studied channel reaches of twenty Chilean gravel-bed rivers from semi-arid Mediterranean to rainy temperate conditions (latitudinal range from 30°19' to 39°56'S) to generate a classification based on geomorphic indicators. Reaches were selected to measure 20 times the width of the active channel, and morphologic features within the active channels were identified through a direct interpretation of aerial photos and remotely sensed images and the use of GIS. Also, river basin topographic conditions were derived from existing digital elevation models and discharge was obtained from national data bases. We used normalized active channel width (W*) and slope (S*), mean elevation, percentage of active channel occupied by islands and number of islands per km, catchment mean slope, and the 2-year return period flood (Q2) as indicators. By means of a hierarchical clustering analysis method and using the squared Euclidean distance metric we classified the study channels in five types. Type I comprises the two northernmost reaches and presents by far the lowest Q2; Type II groups only one reach noticeably different than all the other types, and located just south and with smaller W* but higher S* than Type I channels; Type III includes two channels with higher Q2 than Types I and II, and compared with all other types they feature very low percentage of active channel occupied by islands and number of islands per km and relatively high S*; Type IV includes 12 channels in the latitudinal range from 34°36' to 39°56'S; and finally, the three channels of Type V differ from Type

  10. 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.

  11. 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.

  12. 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. PMID:25544493

  13. 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

  14. 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.

  15. Method for the detachment of culturable bacteria from wetland gravel.

    PubMed

    Weber, Kela P; Legge, Raymond L

    2010-03-01

    The study of bacterial communities in microbially-mediated water treatment systems is becoming increasingly popular. Aquatic bacterial communities are often found in fixed-film environments, residing within a matrix of extracellular polymeric substances commonly referred to as a biofilm. A method for detaching the biofilm is required to either enumerate or characterize these bacterial communities. There are a variety of detachment methods including scraping, swabbing, shaking, sonication, blending, and digestion. The objective of this work was to develop an agitation-based protocol for detachment of culturable bacterial communities from the biofilm surrounding pea gravel from constructed wetland mesocosms. Three different protocol factors were systematically investigated using a triplicated 2(3) factorial design to determine the most effective detachment protocol. Factors studied included: the use of either tap water or phosphate buffer as the shaking/detachment solution; the use of either manual-shaking at room temperature or mechanical shaking at 30 degrees C; and the presence or absence of an enzyme cocktail consisting of lipase, beta-galactosidase and alpha-glucosidase. The resulting suspensions were evaluated for organics, inorganics, culturable bacteria, community level physiological profile (CLPP) and several BIOLOG ECO plate substrate related diversity indices. Using these metrics, the most effective shaking/detachment protocol was identified as mechanical shaking for 3h at 30 degrees C using a phosphate buffer with an enzyme cocktail. PMID:20079767

  16. Thermal EOR requires special design for gravel packs

    SciTech Connect

    Weirich, J.B.; Zaleski, T.E.

    1986-11-17

    Successful gravel-packed completions in thermal recovery wells depend upon proper design and selection of downhole equipment. Equipment designed for normal geothermal environments will generally lack the strength necessary to maintain satisfactory performance throughout the life of the well. Due to increased energy demand, domestic energy shortages, and the increasing cost and risk of exploring for new reserves, enchanced oil recovery (EOR) methods have been developed, pilot tested, and applied in many areas. Methods of which allow operators to take advantage of existing wells and surface equipment are particularly economically attractive. With the unstable price of oil in today's market, few EOR projects will economically justify the re-drilling of wells and replacement of surface facilities to increase production. The most popular EOR method employed for the production of heavy crudes is thermal recovery. Productivity is increased by improving oil mobility and transmissibility in the reservoir. Improvement of ultimate recovery and displacement efficiency is also gained through crude oil expansion and more favorable mobility ratios with injected fluids. Thermal recovery processes involve four major methods: hot waterflooding, cyclic steam injection, steam drive, and in situ combustion. The most basic of these is hot water-flooding which is also the least effective of the thermal recovery processes, because the technique merely involves the injection of hot water and can be adapted to a waterflood project with few surface equipment changes.

  17. Transient response in longitudinal grain size to reduced gravel supply in a large river

    NASA Astrophysics Data System (ADS)

    Singer, Michael Bliss

    2010-09-01

    The first extensive dataset on subaqueous bed material grain size in a large river subject to reduced sediment supply is investigated alongside bathymetry, modeled flow, and sediment flux. Results suggest that following sediment supply decline and a shift to a finer sediment supply, the gravel-sand transition (GST) in fluvial systems extends and subsequently migrates upstream. The non-abrupt (˜125 km) GST in the Sacramento River corresponds with a hump in the long profile, indicating recent downstream redistribution of sediment that impacts grain sizes. The hump is composed of sediments winnowed from upstream gravel beds that accumulate downstream where slope declines. This increases local sorting values and coarse sediment flux rates in the GST, leading to further gravel loss by burial and net efflux. Thus, in a transient response to sediment supply changes, whether anthropogenic or natural, the GST extends upstream as a longitudinally patchy bed modulated by bedload sheet transport that favors the loss of gravel.

  18. Transient response in longitudinal grain size to reduced gravel supply in a large river

    NASA Astrophysics Data System (ADS)

    Singer, M. B.

    2010-12-01

    The first extensive dataset on subaqueous bed material grain size in a large river subject to reduced sediment supply is investigated alongside bathymetry, modeled flow, and sediment flux. Results suggest that following sediment supply decline and a shift to a finer sediment supply, the gravel-sand transition (GST) in fluvial systems extends and subsequently migrates upstream. The non-abrupt (~125 km) GST in the Sacramento River corresponds with a hump in the long profile, indicating recent downstream redistribution of sediment that impacts grain sizes. The hump is composed of sediments winnowed from upstream gravel beds that accumulate downstream where slope declines. This increases local sorting values and coarse sediment flux rates in the GST, leading to further gravel loss by burial and net efflux. Thus, in a transient response to sediment supply changes, whether anthropogenic or natural, the GST extends upstream as a longitudinally patchy bed modulated by bedload sheet transport that favors the loss of gravel.

  19. 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...

  20. 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.

  1. 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

  2. The gravel-sand transition: Sediment dynamics in a diffuse extension

    NASA Astrophysics Data System (ADS)

    Venditti, Jeremy G.; Domarad, Natalia; Church, Michael; Rennie, Colin D.

    2015-06-01

    As gravel-bedded rivers fine in the downstream direction, they characteristically exhibit an abrupt transition from gravel- to sand-bedded conditions. The prevailing theory for why abrupt gravel-sand transitions emerge is based on bed load sorting of a bimodal sediment. The abruptness is thought to be a consequence of sand overwhelming the gravel-sand mixture once it reaches a critical coverage on the bed. The role suspension plays in the development of gravel-sand transitions has not been fully appreciated. The Fraser River, British Columbia, is an archetypical abrupt gravel-sand transition with a "diffuse extension" composed of a sand bed with some patches of gravel. We examine flow, shear stress, and suspended sediment flux in the diffuse extension to better understand sediment dynamics where the sand bed emerges. Sand is carried in suspension upstream of the primary abrupt gravel-sand transition, but in the diffuse extension, sand is moved as both bed load and suspended load. We do not observe downstream gradients in shear stress or suspended sand flux through the diffuse extension that would suggest a gradual "rain out" of sand moving downstream, which raises the question, how is the sand bed formed? Sediment advection length scales indicate that with the exception of very fine sand that moves as wash load in the diffuse extension, fractions coarser than the median sand size cannot be carried in suspension for more than one channel width. This suggests that sand is deposited en masse at the beginning of the diffuse extension, forming a sediment slug at low flood flows that is smeared downstream at high flood flows to form the sand reach.

  3. 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.

  4. Dimensionless critical shear stress in gravel-bed rivers

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    This paper first compiles critical shear stress values from 26 studies of gravel-bed rivers (GBRs) worldwide. The most frequently proposed value of the Shields criterion (θc) is 0.045, but three major groups with θc values ranging from < 0.030 to > 0.100 were identified. Second, dimensionless critical shear stresses (the Shields criterion) were evaluated for 14 GBRs (18 sites) with watershed areas ranging from 12 to 3000 km2. Different approaches were used to identify the initial movement of the bed material: painted and PIT-tag pebbles, sediment traps, and bedload samplers. The Shields criterion (θc) was estimated using the total shear stress (τ) and the grain shear stress (τ‧). Several shear stresses were also estimated using shear velocities. For bedload transport, we obtained an average Shields criterion (θc) of 0.040. The values were higher in small rivers (> 0.050) than larger rivers (< 0.030) because of more significant bedform shear stresses. The Shields criterion (θ‧c) was lower when the grain shear stress (τ‧) was used and only reached 0.019. Different values are also proposed in relation to the type of mobilization: the θc value for partial transport was ~ 0.025 and exceeded 0.040 for full transport (usually reached in association with discharges with a 10-year return period). The values based on the results of sediment traps and a bedload sampler were greater than those obtained using tracers, but these differences are smaller than those usually reported in the literature.

  5. 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.

  6. Use of slope creation for rehabilitating incised, regulated, gravel bed rivers

    NASA Astrophysics Data System (ADS)

    Elkins, Eve M.; Pasternack, Gregory B.; Merz, Joseph E.

    2007-05-01

    Gravel-bedded channels often become incised and degraded below dams. Gravel can be added to the channel to rehabilitate hydrogeomorphic conditions, including those promoting salmon spawning. When implemented without increasing bed slope, gravel addition at downstream riffles back floods upstream riffles. A 2-year gravel augmentation project was done to test the efficacy of a new method for "slope creation." Riffle-to-riffle slope was raised from 0.002 to 0.008 by adding gravel to the most upstream riffle. When gravel was added to the next downstream riffle a year later, riffle-to-riffle slope decreased to the sought after 0.004. After the study, the area of high-quality Chinook salmon spawning habitat increased 471%. The number of redds observed went from 62 to 161 during the study despite a 50% decline of in-river spawners. This eliminates variations in migrant population size and hatchery take as alternative explanations. Slope creation can be a useful aid for rehabilitating regulated rivers.

  7. 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. PMID:27386570

  8. 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

  9. The physical and mechanical properties of laterite gravels from southeastern Nigeria relative to their engineering performance

    NASA Astrophysics Data System (ADS)

    Okagbue, C. O.

    Laterite gravels are used extensively as aggregates for highway construction, concrete making and fills in SE Nigeria. This paper presents results of laboratory investigations carried out to evaluate the physical and mechanical properties of these gravels. High mechanical strength, as measured by aggregate crushing (AC), and Los Angeles abrasion (LAA) values were found to be significant factors controlling the performance. Results indicate that significant correlations exist between these and specific gravity, water absorption and angularity of the gravels. No clear distinction in physical and mechanical properties could be found between the laterite gravels formed over sandstones and shales, indicating perhaps that effects of parent rock on the physical and mechanical nature of laterite gravels is of secondary importance. It is proposed that laterite gravels with AC and LAA values in the range of 30-40% and 34-45%, respectively and 10% fines value of between 8 and 4 tonnes be used only for medium and light trafficked roads. Those with AC and LAA values of less than 30% and 34%, respectively and 10% fines value of greater than 8 tonnes can be used for heavily trafficked roads, provided that acceptable gradation, plasticity limits (on the fines) and other construction specifications are met.

  10. Aeolian processes over gravel beds: Field wind tunnel simulation and its application atop the Mogao Grottoes, China

    NASA Astrophysics Data System (ADS)

    Zhang, Weimin; Tan, Lihai; Zhang, Guobin; Qiu, Fei; Zhan, Hongtao

    2014-12-01

    The aeolian processes of erosion, transport and deposition are threatening the Mogao Grottoes, a world culture heritage site. A field wind tunnel experiment was conducted atop the Mogao Grottoes using weighing sensors to quantify aeolian processes over protective gravel beds. Results reveal that aeolian erosion and deposition over gravel beds are basically influenced by gravel coverage and wind speed. Erosion is a main aeolian process over gravel beds and its strength level is mainly determined by gravel coverage: strong (<30%), medium (30-50%) and slight (>50%). Aeolian deposition only occurs when gravel coverage is equal to or greater than 30% and wind speeds are between 8 and 12 m s-1, and this process continues until the occurrence of the equilibrium coverage. In addition, the change in conditions of external sand supply affects the transition between aeolian deposition and erosion over gravel beds, and the quantity of sand transport at the height of 0-24 mm is an important indicator of aeolian deposition and erosion over gravel beds. Our results also demonstrate that making the best use of wind regime atop the Mogao Grottoes and constructing an artificial gobi surface in staggered arrays, with 30% coverage and 30-mm-high gravels and in 40 mm spacing can trap westerly invading sand flow and enable the stronger easterly wind to return the deposited sand on the gravel surface back to the Mingsha Mountain so as to minimize the damage of the blown sand flux to the Mogao Grottoes.

  11. Laboratory simulation of gravel augmentation downstream of dams: the effect of hydrographs on sediment pulse dynamics

    NASA Astrophysics Data System (ADS)

    Humphries, R.; Sklar, L. S.; Dietrich, W. E.; Wooster, J.; Venditti, J. G.; Minear, J. T.

    2006-12-01

    Gravel augmentation is an increasingly common river restoration strategy downstream of dams where selective transport and lack of gravel resupply have created armored, relatively immobile channel beds. A fundamental challenge in the design of gravel augmentation is predicting the temporal and spatial extent of beneficial bed response to coarse sediment additions, given the range of sediment transport conditions that occur in seasonal and storm-driven hydrographs. Here we report preliminary results of an ongoing series of laboratory flume experiments in which we simulate the addition of pulses of gravel to an armored bed downstream of a dam. These experiments build on the results of early phases of our experimental program, in which we have used constant discharge conditions to explore the translation and dispersion of sediment waves, and mobilization of armored beds by supply of finer sediments, in channels with both suppressed and forced bar pool morphology. Here we use the forced bar morphology channel to compare the evolution of the bed topography and texture following gravel additions for the cases of constant flow and variable flow hydrographs. The experiments are developed in three phases. We first simulate the pre-dam condition by establishing steady-state transport conditions with constant flow, and then simulate dam closure by cutting off sediment supply and allowing the bed to armor and degrade in response to a sequence of hydrographs. We then introduce a gravel pulse on the rising limb of a hydrograph and document the evolution of the pulse and its effects on the bed over a 15 hour hydrograph. The hydrographs were designed assuming a log-normal distribution of discharge over time, and constrained so that the cumulative volume of water supplied during each run is the same for each hydrograph and for the constant flow case. Bed micro-topography is surveyed with computer-driven, cart-mounted laser and sonar systems, and changes in bed texture are documented

  12. 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. PMID:14977152

  13. 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.

  14. 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

  15. 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

  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. Impact of gravel mining on benthic invertebrate communities in a highly dynamic gravel-bed river: an integrated methodology to link geomorphic disturbances and ecological status

    NASA Astrophysics Data System (ADS)

    Béjar, María; Gibbins, Chris; Vericat, Damià; Batalla, Ramon J.; Buendia, Cristina; Lobera, Gemma

    2014-05-01

    Water and sediments are transported along river channels. Their supply, transport and deposition control river morphology and sedimentary characteristics, which in turn support habitat. Floods disturb river channels naturally although anthropogenic impacts may also contribute. River channel disturbance is considered the main factor affecting the organization of riverine communities and contributes to key ecological processes. In this paper we present an integrated methodology designed to analyze the impacts of in-channel gravel mining on benthic invertebrate communities. The study is conducted in the Upper River Cinca (Southern Pyrenees). A 11 km river reach is being monitored in order to understand the effects of floods and gravel mining on channel morphodynamics and invertebrate communities. The study reach is located in and upland gravel-bed system historically and currently affected by periodical episodes of in-channel sediment mining. This methodology has been developed in the background of the research project MorphSed. An integrated methodology of four components (Co) has been designed and is being implemented: (Co1) acquisition of high resolution imagery to generate topographic models before and after channel disturbances. Floods and in-channel gravel mining are considered natural and anthropogenic disturbances, respectively. Topographic models are obtained by means of combining automated digital photogrammetry (SfM) and optical bathymetric models. Event-scale models are used to assess the spatial extent and magnitude of bed disturbance. (Co2) Invertebrate sampling in 5 representative reaches along the study site. Invertebrate surber samples are providing data to define assemblages and their characteristics (composition, density, distribution, traits). These data is used to assess the spatial extent of channel disturbance impacts on the taxonomic and trait structure of communities. (Co3) Monitoring flow and sediment transport in the upstream and downstream

  18. 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

    ... 32 National Defense 4 2012-07-01 2011-07-01 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. 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)...

  20. 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)...

  1. 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

    ... 32 National Defense 4 2013-07-01 2013-07-01 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)...

  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)...

  3. Design and performance of a channel reconstruction project in a coastal California gravel-bed stream.

    PubMed

    Kondolf, G M; Smeltzer, M W; Railsback, S F

    2001-12-01

    A 0.9 km-reach of Uvas Creek, California, was reconstructed as a sinuous, meandering channel in November 1995. In February 1996, this new channel washed out. We reviewed project documents to determine the basis for the project design and conducted our own historical geomorphological study to understand the processes operating in the catchment and project reach. The project was designed using a popular stream classification system, based on which the designers assumed that a "C4" channel (a meandering gravel-bed channel) would be stable at the site. Our historical geomorphological analysis showed that the reach had been braided historically, typical of streams draining the Franciscan Formation in the California Coast Ranges, with episodic flows and high sand and gravel transport. After the project washed out, Uvas Creek reestablished an irregular, braided sand-and-gravel channel, although the channel here was narrower than it had been historically, probably due to such factors as incision caused by gravel mining. Our study casts doubt on several assumptions common in many stream restoration projects: that channel stability is always an appropriate goal; that channel forms are determined by flows with return periods of about 1.5 years; that a channel classification system is an easy, appropriate basis for channel design; and that a new channel form can be imposed without addressing the processes that determine channel form. PMID:11915965

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  5. TRANSPORT OF ORGANIC CONTAMINANTS IN GROUNDWATER: DISTRIBUTION AND FATE OF CHEMICALS IN SAND AND GRAVEL AQUIFERS

    EPA Science Inventory

    The state-of-knowledge of the physical, chemical, and biological processes that are thought to affect organic contaminants in ground water are reviewed. The discussion is confined to horizontal flow in uniform sand and gravel aquifers. General principles governing contaminant tra...

  6. Gravel seeding - A suitable technique for restoring the seabed following marine aggregate dredging?

    NASA Astrophysics Data System (ADS)

    Cooper, Keith; Ware, Suzanne; Vanstaen, Koen; Barry, Jon

    2011-01-01

    Restoration of offshore marine habitats is a relatively new concept, with attempts in the European Union being largely instigated by requirements of various strategic directives. In this experiment, we investigate the practicality and effectiveness of gravel seeding, using a commercial aggregate dredging vessel, in order to recreate a gravel habitat. The experimental design consisted of a Treatment and Control site, both within an area of historic dredging characterised by an overburden of sand, and a gravel dominated Reference site. All sites were surveyed, using a combination of acoustic, camera and grab techniques, 2 months before, and then at 0, 12 and 22 months after the deposition of 4444 m 3 of gravel dominated sediments within the Treatment site. Although financial and practical constraints limited replication of the Treatment to one area, and so precluded strong statistical conclusions, our results suggested that the technique was both practically feasible, and successful in terms of returning the physical and biological attributes at the Treatment site to a state more representative of gravelly substrata in the wider, un-impacted environment.

  7. 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...

  8. Prediction of Bed Load Transport on Small Gravel-Bed Streams

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rates and size distributions of bed load were calculated using 3 transport relations and compared to data collected on three streams with sand-gravel beds in the Goodwin Creek Experimental Watershed in north central Mississippi, USA. Bed load transport rates were greatly over predicted by two of th...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  11. 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

  12. 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

  13. 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

  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. 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.

  17. 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.

  18. 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.

  19. Gravel Bars Can Be Critical for Biodiversity Conservation: A Case Study on Scaly-Sided Merganser in South China

    PubMed Central

    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. PMID:25996671

  20. 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. PMID:25996671

  1. 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.

  2. [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. PMID:26785548

  3. 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. PMID:26965277

  4. 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

  5. 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.

  6. 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.

  7. Troll oil pipeline: Assessment of slope and gravel sleeper stability in steep fjord areas

    SciTech Connect

    Eide, A.; Gudmestad, O.T.; Nadim, F.

    1996-12-01

    This paper describes the slope stability evaluation in the steep areas of the Fensfjord. The main focus in the study has been to establish appropriate undrained shear strength for static and dynamic stability analyses, make a reasonable prediction of the earthquake induced permanent deformation and evaluate the post-earthquake static stability. The special laboratory testing and analysis conducted showed that the only consequence of earthquake loading is limited permanent deformations. Analysis of gravel supports on soft clay showed that three supports needed counter fills in order to fulfill the design requirements. At the tunnel entrance point of the pipeline at Mongstad, the soft clay at the seabed had to be excavated in order to attain satisfactory stability for the gravel support.

  8. 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).

  9. Coarser and rougher: Effects of fine gravel pulses on experimental step-pool channel morphodynamics

    NASA Astrophysics Data System (ADS)

    Johnson, J. P. L.; Aronovitz, A. C.; Kim, W.

    2015-10-01

    Understanding how steep mountain rivers respond to natural and anthropogenic sediment supply perturbations is important for predicting effects of extreme events (e.g., floods and landslides) and for restoring rivers to more natural conditions. Using flume experiments, we show that stabilized step-pool-like channel beds can respond to pulses of finer gravel by becoming even coarser and rougher than before. Adding finer gravel initially reduces bed roughness and also increases the mobility of previously stable bed grains. Small- and intermediate-diameter clasts are then preferentially winnowed from the bed surface, leaving behind higher concentrations of even larger clasts. Ultimately, this results in both a coarser and rougher bed. Our experiments demonstrate that steep river beds become stable through the coevolution of bed roughness and surface grain size distribution and that these morphological variables can be sensitive to the history of upstream sediment supply.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. A two-dimensional discrete particle model of gravel bed river systems

    NASA Astrophysics Data System (ADS)

    MacVicar, B. J.; Parrott, L.; Roy, A. G.

    2006-09-01

    The formation of bed forms in gravel bed rivers acts as a control on stream ecology and the response of rivers to floods. Available models do not reproduce the range of observed bed forms and do not consider interactions between the bed and flow hydraulics. The model presented here considers a gravel bed river as a complex system in which sediment clasts are represented as discrete elements. Simple and local rules describe the sediment and flow dynamics. Using a trimodal sediment distribution, irregular forms that scale with particle diameter develop without explicit feedback mechanisms because of the tendency of large particles to roll along the bed surface and collect into chains. Feedback mechanisms such as imbrication increase the effective entrainment threshold of groups of large particles and increase the stability of these imbricate forms. A second type of bed form is associated with saltating grains and emerges where particles are transported at a preferred distance. The development and maintenance of larger-scale bed forms require feedback between the bed and flow properties. By allowing mean velocity to adjust to bed morphology and considering the effect of acceleration on turbulence generation and mean velocity profiles we demonstrate the emergence of forms similar in morphology to gravel sheets, dunes, and riffle pools. The model is best used to complement field-based studies and is suitable for testing hypotheses of streambed behavior.

  19. 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.

  20. 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.

  1. Through-water terrestrial laser scanning of gravel beds at the plot scale: a preliminary investigation

    NASA Astrophysics Data System (ADS)

    Smith, M. W.; Vericat, D.; Gibbins, C. G.

    2010-12-01

    Natural gravel surfaces are spatially variable. Measurement of their detailed structure is essential for understanding the interaction of roughness with near-bed flows and the sediment entrainment process. However, the acquisition of high resolution topographic data of a river bed is technically demanding where the bed is not regularly exposed by fluctuating water levels. Often the most geomorphologically active portion of a gravel bed river remains submerged even at low stages. Optical reflectance depth monitoring and through-water photogrammetry have been employed to map bed topography over relatively shallow submerged zones. This study presents laboratory and field experiments to demonstrate that through-water terrestrial laser scanning can also be used to provide high resolution DTMs of submerged gravel beds. The resulting point cloud data must be corrected for refraction before the registration process takes place. Additional errors arise from the internal architecture of the scanner as the offset between the arbitrary origin and the point from which the laser emanates must be calculated before refraction correction. These DTMs can be seamlessly embedded within larger sub aerial reach-scale surveys and can be acquired alongside flow measurements to examine the effects of three-dimensional surface geometry on turbulent flow fields.

  2. Suppressing immature house and stable flies in outdoor calf hutches with sand, gravel, and sawdust bedding.

    PubMed

    Schmidtmann, E T

    1991-11-01

    Sand, gravel, sawdust, and pine shavings were used as bedding in outdoor calf hutches and compared with straw relative to the density of immature (maggot) house flies, Musca domestica, and stable flies, Stomoxys calcitrans. In 6-wk field trials, average densities of house and stable fly maggots in concrete mix sand ranged from only .3 to 1.6 and 0 to .1 maggots/L, respectively; pea size gravel bedding also strongly suppressed densities from less than .1 to .3 and less than .1 to .1 maggots/L, respectively. These densities represent reductions of 76 to greater than 99% relative to straw bedding, but both sand and gravel compacted and became soiled with calf feces, which resulted in unacceptable bedding sanitation and foul odors. Densities of house and stable fly maggots in pine shavings did not differ from those in straw bedding. Nevertheless, in sawdust bedding, maggot density was limited to averages of 1.4 to 8.3 house and 9.8 to 11.8 stable fly maggots/L; this represented reductions of 45 to 91% relative to straw. In a follow-up trial, house and stable fly maggot densities in sawdust averaged 11.3 and 43.9 maggots/L, respectively, reductions of 77 and 46%. These findings suggest that bedding calf hutches with sawdust during warm weather can be useful as an ecologically sound approach to controlling muscoid fly populations on dairy farms. PMID:1757634

  3. 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.

  4. 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

  5. THE CONFIGURATION AND THE FORMING PROCESS OF RIVER CHANNEL INFLUENCED BY RIVER CROSSING STRUCTURES AND GRAVEL MINING

    NASA Astrophysics Data System (ADS)

    Harada, Daisuke; Chibana, Takeyoshi; Yamashita, Kimiko

    In many Japanese gravel-bed rivers, during these 30 years, river morphology has changed from single channel to compound channel, and the black locust has been rapidly spreading its habitat in the flood channel. It is said that this change has been caused by past gravel mining and the construction of river-crossing structures. This study aims to reveal how these human impacts affected and altered the river configuration. Previous study pointed out that theriver slope is determined by the size of sediment and the flow condition. In the Tama River, however, it was pointed out that the loss of cobbles and boulders due to gravel mining made the riverbed slope in low flow channel milder than before and formed compound channel. The low flow channel width was narrowest just downstream of a river-crossing structure but increased in the flow direction and was largest upstream of the next structure. This situation was also seen in other gravel-bed rivers, and its ecosystem was strongly related to the height of the weir and the length between a structure and a structure. In the upstream area of the alluvial fan of the Tama river, in 1968, when gravel mining had finished, bedrock was exposed in a lot of places due to gravel mining. This bedrock was firstly eroded just downstream of each structure, and the erosion progressed in the flow direction. This erosion formed low flow channel, and in its flood channel, the suitable condition for the black locust, which was revealed in this paper, was formed during several heavy floods and caused sudden expansion of blacklocust. On the other hand, from the upstream of the next structure, deposited sediment has formed gravel-bed river toward upstream direction. As a result, boundary of eroded channel and gravel-bed channel was formed between the structures.

  6. 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.

  7. Salt-tracer experiments to measure hyporheic transit time distributions in gravel-bed sediments

    NASA Astrophysics Data System (ADS)

    van der Perk, M.; Petticrew, E. L.; Owens, P. N.; Hulsman, R.; Wubben, L.

    2009-04-01

    We performed a series of tracer experiments in large outdoor flumes at the Quesnel River Research Centre, Likely, BC, Canada to quantify the hyporheic transit time distribution in gravel bed sediments. For this purpose, an 18.9 m x 2 m flume was filled with a 30 cm thick layer of well-sorted gravel with a d50 of 39.1 mm. The average longitudinal gradient of the gravel bed was 0.05% The flumes were filled with aerated local groundwater, so that a standing water layer of 20 cm depth over the gravel bed was established. Subsequently, dissolved common salt was added until the water reached an electrical conductivity (EC) between 450 and 550 µS/cm. The flumes were equilibrated overnight to ensure a uniform distribution of the salt concentration across the flume. At the start of each experiment local groundwater (EC = 150 µS/cm) was discharged at a rate of approximately 16 l/s at the upper end of the flume. At 10 m downstream from the inlet the EC was monitored in the water layer until the EC remained constant at a value close to the background value of about 150 µS/cm. The experiment was replicated three times. The measured breakthrough curves were used to calculate the overall transit time distributions of water in the 10 m stretch of the flume. The transit time distribution in the water layer was calculated using the longitudinal dispersion coefficient estimated using the empirical equation of Fischer et al. (1979). For the transit time distributions within the gravel layer we assumed a probability density function as proposed by Marion and Zaramella (2005). These hyporheic transit time distributions were estimated using least-squares deconvolution of the overall transit time distributions. The fitted overall transit time distributions corresponded fairly well to the ‘observed' distributions. The 10th percentile of the hyporheic transit time distributions in the 10 m stretch of the flume varied between 45 s and 65 s. The median transit time ranged between 200 s

  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. 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.

  11. 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.

  12. Suspended sediment transport during in-channel gravel mining: spatial and temporal dynamics

    NASA Astrophysics Data System (ADS)

    Tena, Alvaro; Béjar, María; Muñoz, Efrén; Ramos, Ester; Lobera, Gemma; Andrés López-Tarazón, Jose; Gibbins, Chris; Batalla, Ramon J.; Piqué, Gemma; Vericat, Damià

    2015-04-01

    Rivers in natural conditions tend to maintain long-term morphosedimentary equilibrium, however, natural and human induced disturbances (e.g. flooding, damming, gravel mining, etc.) may alter this equilibrium by modifying physical and ecological processes and dynamics. Gravel mining activities cause major changes in the channel mass and energy balances, that in turn affect morphology, bed sedimentology and habitat conditions. In-channel gravel extractions also increase suspended sediment concentrations, locally but with downstream associated effects. The excess of sediments can clog the interstices between substrate clasts, increasing the invertebrate drift, and reducing the available habitat for benthic organisms. The Upper River Cinca (Southern Pyrenees, Iberian Peninsula) has experienced gravel mining activities in the active channel and floodplain since the middle of the last century, although their morpho-sedimentary impacts have never been fully investigated. Nowadays, these practices are still carried out in the upper Cinca, but mainly to prevent damages in infrastructures. One of these extractions has been experimentally monitored in the background of the research project MorphSed (www.morphsed.es). Suspended sediment transport has been monitored before, during and after the gravel extraction in order to assess the spatial and temporal dynamics and their potential impacts in the downstream reaches. Suspended sediment samples were collected manually (Depth integrated sampler DH49) and automatically (ISCO 3700 automatic sampler) at four sampling locations, one just downstream from the mining (M1) and the other two sections (M2, M3) located 100 and 300 m downstream. Additionally, turbidity was continuously registered (every 15 minutes) in the last section (M3). Preliminary results show as during the first field day, when the channel was partially diverted, sediment concentrations increased locally and decreased downstream. Mean suspended sediment concentrations

  13. 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

  14. 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. PMID:23925197

  15. Width adjustment in experimental gravel-bed channels in response to overbank flows

    NASA Astrophysics Data System (ADS)

    Pitlick, John; Marr, Jeff; Pizzuto, Jim

    2013-06-01

    We conducted a series of flume experiments to investigate the response of self-formed gravel-bed channels to floods of varying magnitude and duration. Floods were generated by increasing the discharge into a channel created in sand- and gravel-sized sediment with a median grain size of 2 mm. Flooding increased the Shields stress along the channel perimeter, causing bank erosion and rapid channel widening. The sediment introduced to the channel by bank erosion was not necessarily deposited on the channel bed, but was rather transported downstream, a process likely facilitated by transient fining of the bed surface. At the end of each experiment, bank sediments were no longer in motion, "partial bed load transport" characterized the flat-bed portion of the channel, and the Shields stress approached a constant value of 0.056, about 1.2 times the critical Shields stress for incipient motion. Furthermore, the discharge was entirely accommodated by flow within the channel: the creation of a stable channel entirely eliminated overbank flows. We speculate that similar processes may occur in nature, but only where bank sediments are non-cohesive and where channel-narrowing processes cannot counteract bank erosion during overbank flows. We also demonstrate that a simple model of lateral bed load transport can reproduce observed channel widening rates, suggesting that simple methods may be appropriate for predicting width increases in channels with non-cohesive, unvegetated banks, even during overbank flows. Last, we present a model for predicting the equilibrium width and depth of a stable gravel-bed channel with a known channel-forming Shields stress.

  16. 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. PMID:26434026

  17. 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

  18. 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).

  19. 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. PMID:25545280

  20. 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

  1. Modeling of sediment transport through stormwater gravel filters over their lifespan.

    PubMed

    Siriwardene, Nilmini R; Deletic, Ana; Fletcher, Tim D

    2007-12-01

    Gravel filter media are widely used for attenuation and treatment of runoff in a range of stormwater management systems, including infiltration trenches/basins, porous pavements, and soakaways. These systems essentially reduce the effective impervious area of a catchment and also provide stormwater detention and infiltration into the surrounding soils, thus helping to restore predevelopment hydrology. Although it is well-known that these systems eventually clog and their treatment performance diminishes with time, no model developed has so far been developed to predict this behavior. The aim of this study was to develop a mathematical model of the transport of sediment through stormwater gravel filters over their lifespan. A detailed laboratory study of sediment transport was undertaken for different stormwater inflow regimes until the system became clogged. These data were used to test two models, the k-C* model (the first-order decay model) and the Yao model (a physically based model). Although these models were able to predict sediment behavior in clean filters (i.e., at the start of their life), both failed to accurately simulate observed behavior once the filter accumulated sediment. The main variables that impact the sediment process in dirty filters were quantified, and modifications to the Yao model were proposed. The modified model, with three calibration parameters, was calibrated for concentrations of total suspended solids. This model could be used in practice to asses the maintenance requirements of a gravel filter. Although developed for stormwater management, the model could be applied to a number of other disciplines, such as water treatment and groundwater recharge. PMID:18186343

  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. 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

  4. 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. PMID:1367420

  5. Fluvial sediment inputs to upland gravel bed rivers draining forested catchments: potential ecological impacts

    NASA Astrophysics Data System (ADS)

    Marks, S. D.; Rutt, G. P.

    As identified by the detailed long-term monitoring networks at Plynlimon, increased sediment supply to upland fluvial systems is often associated with forestry land-use and practice. Literature is reviewed, in the light of recent results from Plynlimon sediment studies, to enable identification of the potential ecological impacts of fluvial particulate inputs to upland gravel bed rivers draining forested catchments similar to the headwaters of the River Severn. Both sediment transport and deposition can have significant impacts upon aquatic vertebrates, invertebrates and plants.

  6. 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

  7. 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.

  8. Well completion technology. Multiuse polymer protects injection well during drilling, underreaming, gravel packing

    SciTech Connect

    Davis, K.E.; Jarrell, M.D.

    1983-12-12

    Fluids for drilling, gravel-packing, and completion were optimized for an expensive injection well. Successful engineering gave maximum injection rates and no skin damage, while accomplishing all the fundamental drilling and suspension functions of fluids. Formation protection was critical. The approximately $5-million well was planned for chemical waste disposal, and plant capacity is limited by injectivity. This work describes the fluid, hardware, and techniques used. The 3 distinct fluids were variations on the same polymer-based system. Results of tests showed that Kelzan XCD Polymer, a dispersible form of xanthan gum, had the most applicable overall properties.

  9. 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.

  10. 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., Jr.; 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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. PMID:16538418

  18. 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.

  19. Sounds and vibrations in the frozen Beaufort Sea during gravel island construction.

    PubMed

    Greene, Charles R; Blackwell, Susanna B; McLennan, Miles Wm

    2008-02-01

    Underwater and airborne sounds and ice-borne vibrations were recorded from sea-ice near an artificial gravel island during its initial construction in the Beaufort Sea near Prudhoe Bay, Alaska. Such measurements are needed for characterizing the properties of island construction sounds to assess their possible impacts on wildlife. Recordings were made in February-May 2000 when BP Exploration (Alaska) began constructing Northstar Island about 5 km offshore, at 12 m depth. Activities recorded included ice augering, pumping sea water to flood the ice and build an ice road, a bulldozer plowing snow, a Ditchwitch cutting ice, trucks hauling gravel over an ice road to the island site, a backhoe trenching the sea bottom for a pipeline, and both vibratory and impact sheet pile driving. For all but one sound source (underwater measurements of pumping) the strongest one-third octave band was under 300 Hz. Vibratory and impact pile driving created the strongest sounds. Received levels of sound and vibration, as measured in the strongest one-third octave band for different construction activities, reached median background levels <7.5 km away for underwater sounds, <3 km away for airborne sounds, and <10 km away for in-ice vibrations. PMID:18247873

  20. 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.

  1. Combination fracturing/gravel-packing completion technique on the Amberjack, Mississippi Canyon 109 field

    SciTech Connect

    Hannah, R.R.; Park, E.I.; Porter, D.A.; Black, J.W. )

    1994-11-01

    This paper describes a one-step fracturing/gravel-pack (frac-and-pack) completion procedure conducted on the BP Exploration Amberjack platform beginning in early 1992. This platform is 35 miles southwest of Venice, LA. The first four completions on this platform had an average positive skin values of 21. The goal of the frac-and-pack procedure was to reduce these skins to nearly zero. In total, 24 frac-and-pack operations were performed. Details of the fracture design, prefracture testing, fracture design and execution, and production response and a continuing optimization program are discussed. The fractures were performed with the screens in place with the gravel pack after the fracturing operation. The treatments were designed for the tip screenout technique to create wide fractures and to provide proppant loadings exceeding 8 lbm/ft. This paper presents the trend of the declining skin values, along with a discussion of time-dependent skins. The changes in fluids, breakers, and proppants are also presented. The average skin on 14 frac-and-pack completions was 5.3. The average skin on the final eight completions was 0.2.

  2. Sediment Transport Modeling Along the Gravel-Sand Transition Zone of the Snohomish River, WA

    NASA Astrophysics Data System (ADS)

    DeVries, P.; Huang, C.; Aldrich, R.

    2014-12-01

    Long term sediment trapping efficiency was modeled for 1000-2000 ft long analysis segments of the tidally influenced, diked Snohomish River, upstream, along, and downstream of the ~3.5 mile long gravel-sand transition zone. A depth-averaged 2-dimensional hydrodynamic model was calibrated to a recent flood with a ~25 year recurrence interval, and the output used to extract parameters used to estimate shear stress over a range of high flows. Shear stress was estimated using (i) a roughness relation and (ii) the uniform flow approximation. Riverbed grain size distributions were estimated using pebble counts upstream, and Ponar grab samples within and downstream of the transition zone. Four different gravel and sand transport equations (Engelund-Hansen, Ackers-White, Wilcock-Crowe, and Yang) were applied to estimate transport rates at each flow level analyzed. The resulting rates were integrated over a 50 year period to compute total load entering and exiting each analysis segment to evaluate long term trends in bed elevation profiles. Results were sensitive to the choice of shear stress and bedload transport estimator with most method-dependent variation in trends apparent for segments within the transition zone.

  3. Large submarine sand waves and gravel lag substrates on Georges Bank off Atlantic Canada

    USGS Publications Warehouse

    Todd, B.J.; Valentine, Page C.

    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. 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.

  5. 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. PMID:25916476

  6. 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

  7. 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

  8. 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

  9. 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

  10. 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

  11. Biogeomorphology: Effects of Salmon Redds on River Hydraulics and Hyporheic Flow in Gravel-Bed Rivers

    NASA Astrophysics Data System (ADS)

    Tonina, D.; Buffington, J. M.

    2005-12-01

    Salmonids, many of which are currently at risk world wide, bury their eggs in streambed gravels for incubation within the near-surface hyporheic zone. During construction of their nests (redds), a female salmon digs a pit in which the eggs are laid, and then covers them with the spoils of a second upstream pit. Redd construction modifies channel topography, creating a pit and a downstream hump (tailspill), the dimensions of which can be comparable to macro-scale bedforms. Additionally, spawning activity winnows fine grains from the streambed, resulting in relatively coarser and more porous sediment, with higher hydraulic conductivity than the undisturbed bed material. Here, we examine the effects of a salmon nest on local river hydraulics and hyporheic flow in a gravel pool-riffle channel. A computational fluid dynamics model is used to simulate channel hydraulics and shallow hyporheic flow through a single pool-riffle sequence with, and without, a redd placed at the pool tail (a typical spawning location because of downwelling hyporheic flow induced by near-bed pressure variations caused by pool and riffle topography). For the numerical model, we use scaled values of channel and redd dimensions surveyed in gravel-bed rivers of central Idaho. Results confirm that pool tails, where redds are commonly constructed, are areas of high pressure and downwelling. Moreover, hyporheic flow generated by pool-riffle topography creates marginally suitable subsurface habitat for salmonid eggs even without the effects of redds; there is sufficient downwelling with adequate hyporheic velocity and oxygen content for egg survival at depths where egg pockets would be located. However, the presence of salmon nests significantly changes local river hydraulics and local patterns of upwelling and downwelling, enhancing the flow velocity and dissolved oxygen concentration through the egg pocket, thereby potentially enhancing offspring survival. These findings demonstrate that salmonids

  12. 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

  13. 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

  14. 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.

  15. 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.

  16. A study of radioactivity in modern stream gravels and its possible application as a prospecting method

    USGS Publications Warehouse

    Chew, Randall T., III

    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.

  17. 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.

  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...

  19. 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...

  20. 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...

  1. 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...

  2. Trends of grain sizes on gravel bars in the Rio Chagres, Panama

    NASA Astrophysics Data System (ADS)

    Rengers, Francis; Wohl, Ellen

    2007-01-01

    We examined the trends of grain sizes along the upper 414 km 2 of the mountainous Rio Chagres drainage basin in Panama. Gravel bars were sampled along 40 km of the Rio Chagres and five major tributary streams using a transect pebble count of median diameter, lithology, and clast rounding. Although previous investigators have found that downstream fining can be obscured by inputs of colluvial sediment and other local controls in mountain drainages, we decided to examine the trends of grain sizes along a tropical mountain river where rapid weathering and high capability of transport might be capable of overriding the input effects of colluvium. Specifically, we tested the hypotheses that downstream fining would be present as a result of selective sorting, and that weak felsic particles would decrease in size preferentially to strong mafic particles because of abrasion. Statistical analyses reveal a weak downstream decrease of sediment size on gravel bars along the study reach of the Rio Chagres, with a Sternberg diminution coefficient ( α) for felsic and mafic grains of - 0.013 and - 0.017, respectively. Felsic clasts have thicker weathering rinds and become rounded downstream faster than mafic particles, but tumbling-mill tests of abrasion show no significant differences in rate of mass loss in relation to lithology, and downstream decreases in grain size are similar between lithologies. Dividing the study reach into six sub-reaches bounded by major tributary junctions, we further tested the hypothesis that downstream trends in fining might be obscured at the basin scale by sediment input from tributaries, but that trends in grain sizes might be more visible at the reach scale between tributaries. We did not find any consistent trends in grain size between tributaries. Stream width appears to assert a local control on grain size; coarse particles are associated with narrow channel reaches, whereas smaller particles are associated with wide channel reaches.

  3. Channel adjustments to a succession of water pulses in gravel bed rivers

    NASA Astrophysics Data System (ADS)

    Ferrer-Boix, Carles; Hassan, Marwan A.

    2015-11-01

    Gravel bed rivers commonly exhibit a coarse surface armor resulting from a complex history of interactions between flow and sediment supply. The evolution of the surface texture under single storm events or under steady flow conditions has been studied by a number of researchers. However, the role of successive floods on the surface texture evolution is still poorly understood. An experimental campaign in an 18 m-long 1 m-wide flume has been designed to study these issues. Eight consecutive runs, each one consisting of a low-flow period of variable duration followed by a sudden flood (water pulse) lasting 1.5 h, have been conducted. The total duration of the experiment was 46 h. The initial bed surface was created during a 280 h-long experiment focused on the influence of episodic sediment supply on channel adjustments. Our experiments represent a realistic armored and structured beds found in mountain gravel bed rivers. The armor surface texture persists over the duration of the experiment. The experiment exhibits downstream fining of the bed-surface texture. It was found that sorting processes were affected by the duration of low-flow between flood pulses. Since bed load transport is influenced by sediment sorting, the evolution of bed load transport is impacted by the frequency of the water pulses: short interpulse durations reduce the time over which fine material (transported as bed load) can be winnowed. This, in turn, contributes to declining reduction of the bed load transport over time while the sediment storage increases.

  4. 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. PMID:23178886

  5. 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.

  6. Remote Mapping of River Gravel Interstitial Spaces Availability for Juvenile Salmon Sheltering (Invited)

    NASA Astrophysics Data System (ADS)

    Bergeron, N.; Calsamiglila, A.; Dugdale, S. J.; Bérubé, F.

    2013-12-01

    Juvenile salmonid use interstitial gravel spaces to shelter from predators and adverse hydroclimatic conditions. Shelter availability is therefore a key habitat factor to consider in habitat quality mapping. Finstad et al. (2007) developed a method for the measurement of shelter availability in the field using PVC tubes of various diameter and length. The method, which involves probing the bed with the tubes, provides high quality measurements of shelter abundance and size distribution but it is laborious and exceedingly time consuming to apply at large spatial scales. We tested two different remote methods for estimating substrate shelter availability at a large number of sampled locations over a test gravel bed reach of the Restigouche river, an Atlantic salmon river of the Gaspésie peninsula, Québec, Canada. At each sampled location, Finstad's method was first used to measure "true" reference shelter characteristics. Then, the two remote methods were used to estimate shelter characteristics over the same sampled locations. The first remote method used Agisoft Photoscan to produce hi-resolution 3D models of river bed surfaces from close-range (<150 cm from the bed) digital images of the sampled bed areas. Various methods were developed and tested for extracting shelters from these models. The second remote method used high-resolution airborne imagery to extract textural properties of the images over the sampled locations and to calibrate relationships between texture values and shelter characteristics as measured with Finstad's method. In this presentation, the performance of these two methods is analysed with regards to their ability to provide adequate estimates of shelter availability over large spatial scales.

  7. Image analysis for measuring stratigraphy in sand-gravel laboratory experiments

    NASA Astrophysics Data System (ADS)

    Orrú, C.; Chavarrías, V.; Uijttewaal, W. S. J.; Blom, A.

    2013-11-01

    Measurements of spatial and temporal changes in the grain size distribution are crucial to improving the modelling of sediment transport and associated grain size-selective processes. We present three complementary techniques to determine such variations in the grain size distribution in sand-gravel laboratory experiments, as well as the resulting stratigraphy: (1) particle colouring, (2) removal of sediment layers, and (3) image analysis. The resulting stratigraphy measurement method has been evaluated in two sets of experiments. In both sets three grain size fractions within the range of coarse sand to fine gravel were painted in different colours. Sediment layers are removed using a wet vacuum cleaner. Subsequently areal images are taken of the surface of each layer. The areal fraction content, i.e. the relative presence of each size fraction over the bed surface, is determined using a colour segmentation algorithm which provides the areal fraction content of a specific colour (i.e., grain size) covering the bed surface. Particle colouring is not only beneficial to this type of image analysis but also observing and understanding grain size-selective processes. The stratigraphy based on areal fractions is measured with sufficient accuracy. Other advantages of the proposed stratigraphy measurement technique are: (a) rapid collection and processing of a large amount of data, (b) very high spatial density of information on the grain size distribution (so far unequalled in other methods), (c) the lack of disturbances to the bed surface, (d) only minor disturbances to the substrate due to the removal of sediment layers, and (e) the possibility to return a sediment layer at its original elevation and continue the flume experiment. The areal fractions can be converted into volumetric fractions using a conversion model. The proposed empirical conversion model is based on a comparison between the photogrammetry results and dry sieve analysis.

  8. Image analysis for measuring the size stratification in sand-gravel laboratory experiments

    NASA Astrophysics Data System (ADS)

    Orrú, C.; Chavarrías, V.; Uijttewaal, W. S. J.; Blom, A.

    2014-04-01

    Measurements of spatial and temporal changes in the grain-size distribution of the bed surface and substrate are crucial to improving the modelling of sediment transport and associated grain-size selective processes. We present three complementary techniques to determine such variations in the grain-size distribution of the bed surface in sand-gravel laboratory experiments, as well as the resulting size stratification: (1) particle colouring, (2) removal of sediment layers, and (3) image analysis. The resulting stratification measurement method was evaluated in two sets of experiments. In both sets three grain-size fractions within the range of coarse sand to fine gravel were painted in different colours. Sediment layers are removed using a wet vacuum cleaner. Subsequently areal images are taken of the surface of each layer. The areal fraction content, that is, the relative presence of each size fraction over the bed surface, is determined using a colour segmentation algorithm which provides the areal fraction content of a specific colour (i.e. grain size) covering the bed surface. Particle colouring is not only beneficial to this type of image analysis but also to the observation and understanding of grain-size selective processes. The size stratification based on areal fractions is measured with sufficient accuracy. Other advantages of the proposed size stratification measurement method are (a) rapid collection and processing of a large amount of data, (b) a very high spatial density of information on the grain-size distribution, (c) the lack of disturbances to the bed surface, (d) only minor disturbances to the substrate due to the removal of sediment layers, and (e) the possibility to return a sediment layer to its original elevation and continue the flume experiment. The areal fractions are converted into volumetric fractions using an existing conversion model.

  9. 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. PMID:22728828

  10. The importance of fires and floods on tree ages along mountainous gravel-bed streams.

    PubMed

    Charron, I; Johnson, E A

    2006-10-01

    This paper examines the commonly accepted assumption in the riparian literature that areas adjacent to streams do not burn. Using time-since-fire distributions, derived from stand-origin maps for a watershed in the front ranges of the Canadian Rocky Mountains, we found that the areas adjacent to streams and the whole study watershed have similar fire frequencies. In addition, the relative importance of fires and floods is regulated by a change in channel morphology associated with the creation of bars. The results demonstrate that fires solely control tree establishment along straight streams without bars, while the influence of floods is observed at the onset of lateral- and point-bar formation. This occurs because bars are formed in-channel and require smaller discharges in order to be flooded, compared to higher terraces. Consequently, bars are the only surfaces being flooded more frequently than they are being burned. Thus, overall the results indicate that, on this watershed, areas adjacent to streams are not less likely to burn than the uplands, except for lateral and point bars. The generality of these results to other systems should be tested as they have important implications for current forest ecological definition of "riparian zones," which typically include all fluvially derived landforms, from the channel banks to the terraces. Indeed, this study suggests that along smaller, headwater, gravel-bed mountain watersheds, the forests found on terraces are only influenced by fire and not fluvial processes and should therefore not be included in the riparian zone, while the forests on bars are the only surfaces currently being influenced by fluvial processes. Such a change in definition has implications for both ecologists and forest managers aiming to protect areas along streams as they now must take into account the effects of two disturbances on these small gravel-bed streams. PMID:17069369

  11. 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

  12. 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

  13. USE OF GREENHOUSE CHAMBERS FOR ENHANCING GROWTH OF TUNDRA TRANSPLANTS ON THIN GRAVEL FILL IN PRUDHOE BAY, ALASKA

    EPA Science Inventory

    An approach is presented that could facilitate disturbed tundra revegetation and monitoring in Alaska North Slope Oil Fields. xperiments were conducted on an abandoned drilling pad where the gravel was removed to a thin layer (Ca. 20 am) above tundra grade and mixed with underlyi...

  14. Fine gravel controls hydrologic and erodibility responses to trampling disturbance for coarse-textured soils with weak cyanobacterial crusts.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  15. 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+...

  16. 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.

  17. Effect of replacing surface inlets with blind or gravel inlets on sediment and phosphorus subsurface drainage losses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  18. 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%. PMID:21090554

  19. 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.

  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. 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

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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

  7. 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. PMID:26520300

  8. The impact of ellipsoidal particle shape on pebble breakage in gravel

    PubMed Central

    Tuitz, Christoph; Exner, Ulrike; Frehner, Marcel; Grasemann, Bernhard

    2012-01-01

    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. PMID:26321870

  9. 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.

  10. Coupling fluvial-hydraulic models to predict gravel transport in spatially variable flows

    NASA Astrophysics Data System (ADS)

    Segura, Catalina; Pitlick, John

    2015-05-01

    This study investigated spatial-temporal variations of shear stress and bed load transport at three gravel bed river reaches of the Williams Fork River, Colorado. A two-dimensional flow model was used to compute spatial distributions of shear stress (τ) for four discharge levels between one third of bankfull (Qbf) and Qbf. Results indicate that mean τ values are highly variable among sites. However, the properties of the mean-normalized distributions of τ are similar across sites for all flows. The distributions of τ are then used with a transport function to compute bed load transport rates of individual grain size fractions. Probability distributions of the instantaneous unit-width transport rates, qb, indicate that most of the bed load is transported through small portions of the bed with high τ. The mean-normalized probability distributions of qb are different among sites for all flows except at Qbf, when the distributions overlap. We also find that the grain size distribution (GSD) of the bed load adjusts with discharge to resemble the grain size distribution of the subsurface at Qbf. We extend these results to 13 locations in the basin, using the mean-normalized distributions of shear stress and measured subsurface grain sizes to compute bed load transport rates at Qbf. We found a remarkably similar shape of the qb distribution among sites highlighting the basin-wide balance between flow forces and GSD at Qbf and the potential to predict sediment flux at the watershed scale.