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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. 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

  18. 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.

  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. 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...

  1. 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.

  2. 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.

  3. 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.

  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. 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

  1. 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.

  2. 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...

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

    NASA Astrophysics Data System (ADS)

    Kondolf, G. M.; Williams, J.

    2003-12-01

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

  10. 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.

  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. 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...

  4. 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

  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. 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

  12. 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.

  13. 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

  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. 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.

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

    EPA Science Inventory

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

  19. 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.

  20. 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.

  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.

    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

  6. 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

  7. 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.

  8. 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.

  9. 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.

  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. 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...

  4. 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...

  5. 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.

  6. 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...

  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. 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...

  9. 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

  10. 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...

  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. 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.

  15. 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.

  16. 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.

  17. 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.

  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. 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

  3. [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

  4. 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.

  5. 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.

  6. 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.

  7. 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

  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. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  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. 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.

  16. 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.

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

    NASA Astrophysics Data System (ADS)

    Lamb, Michael P.; Venditti, Jeremy G.

    2016-04-01

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

  18. 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.

  19. 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.

  20. 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

  1. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  3. 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. 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.

  5. 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.

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

    PubMed Central

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

    2009-01-01

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

  7. 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

  8. 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

  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. 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

  14. 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

  15. 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).

  16. 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

  17. 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.

  18. 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

  19. Edge Effects Are Important in Supporting Beetle Biodiversity in a Gravel-Bed River Floodplain

    PubMed Central

    Langhans, Simone D.; Tockner, Klement

    2014-01-01

    Understanding complex, dynamic, and diverse ecosystems is essential for developing sound management and conservation strategies. Gravel-bed river floodplains are composed of an interlinked mosaic of aquatic and terrestrial habitats hosting a diverse, specialized, and endangered fauna. Therefore, they serve as excellent models to investigate the biodiversity of multiple ecotones and related edge effects. In this study, we investigated the abundance, composition, richness, and conservation status of beetle assemblages at varying sediment depth (0, 0.1, 0.6 and 1.1 m), distance from the channel (1, 5, 20, and 60–100 m, and 5 m within the riparian forest), and time of the year (February–November) across a 200 m-wide gravel bar at the near-natural Tagliamento River (Italy), to detect edge effects in four floodplain ecotones: aquatic-terrestrial, forest-active floodplain, sediment-air, and sediment-groundwater. We used conventional pitfall traps and novel tube traps to sample beetles comparably on the sediment surface and within the unsaturated sediments. We found a total of 308 beetle species (including 87 of conservation concern) that showed multiple, significant positive edge effects across the floodplain ecotones, mainly driven by spatial heterogeneity: Total and red list beetle abundance and richness peaked on the sediment surface, at channel margins, and at the edge of the riparian forest. All ecotones possessed edge/habitat specialists. Most red list species occurred on the sediment surface, including five species previously considered extinct – yet two of these species occurred in higher densities in the unsaturated sediments. Conservation and management efforts along gravel-bed rivers must therefore promote a dynamic flow and sediment regime to create and maintain habitat heterogeneity and ecotone diversity, which support a unique and high biodiversity. PMID:25545280

  20. 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

  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. 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

  3. 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

  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. 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.

  7. 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.

  8. 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

  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. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. A GIS approach to model sediment reduction susceptibility of mixed sand and gravel beaches.

    PubMed

    Eikaas, Hans S; Hemmingsen, Maree A

    2006-06-01

    The morphological form of mixed sand and gravel beaches is distinct, and the process/response system and complex dynamics of these beaches are not well understood. Process response models developed for pure sand or gravel beaches cannot be directly applied to these beaches. The Canterbury Bight coastline is apparently abundantly supplied with sediments from large rivers and coastal alluvial cliffs, but a large part of this coastline is experiencing long-term erosion. Sediment budget models provide little evidence to suggest sediments are stored within this system. Current sediment budget models inadequately quantify and account for the processes responsible for the patterns of erosion and accretion of this coastline. We outline a new method to extrapolate from laboratory experiments to the field using a geographical information system approach to model sediment reduction susceptibility for the Canterbury Bight. Sediment samples from ten representative sites were tumbled in a concrete mixer for an equivalent distance of 40 km. From the textural mixture and weight loss over 40 km tumbling, we applied regression techniques to generate a predictive equation for Sediment Reduction Susceptibility (SRS). We used Inverse Distance Weighting (IDW) to extrapolate the results from fifty-five sites with data on textural sediment composition to field locations with no data along the Canterbury Bight, creating a continuous sediment reductions susceptibility surface. Isolines of regular SRS intervals were then derived from the continuous surface to create a contour map of sediment reductions susceptibility for the Canterbury Bight. Results highlighted the variability in SRS along this coastline. PMID:16538418

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  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. 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

  8. 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

  9. 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

  10. 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

  11. 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

  12. 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.

  13. 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.

  14. 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

  15. 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

  16. 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.

  17. 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.

  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. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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

  7. 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.

  8. 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

  9. 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

  10. 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.

  11. 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.

  12. 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+...

  13. 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.

  14. 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

  15. 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...

  16. 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...

  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. Estimation of recharge rates to the sand and gravel aquifer using environmental tritium, Nantucket Island, Massachusetts

    USGS Publications Warehouse

    Knott, Jayne Fifield; Olimpio, Julio C.

    1986-01-01

    Estimation of the average annual rate of ground-water recharge to sand and gravel aquifers using elevated tritium concentrations in ground water is an alternative to traditional steady-state and water-balance recharge-rate methods. The concept of the tritium tracer method is that the average annual rate of ground-water recharge over a period of time can be calculated from the depth of the peak tritium concentration in the aquifer. Assuming that ground-water flow is vertically downward and that aquifer properties are reasonably homogeneous, and knowing the date of maximum tritium concentration in precipitation and the current depth to the tritium peak from the water table, the average recharge rate can be calculated. The method, which is a direct-measurement technique, was applied at two sites on Nantucket Island, Massachusetts. At site 1, the average annual recharge rate between 1964 and 1983 was 26.1 inches per year, or 68 percent of the average annual precipitation, and the estimated uncertainty is ?15 percent. At site 2, the multilevel water samplers were not constructed deep enough to determine the peak concentration of tritium in ground water. The tritium profile at site 2 resembles the upper part of the tritium profile at site 1 and indicates that the average recharge rate was at least 16 .7 inches per year, or at least 44 percent of the average annual precipitation. The Nantucket tritium recharge rates clearly are higher than rates determined elsewhere in southeastern Massachusetts using the tritium, water-table-fluctuation, and water-balance (Thornthwaite) methods, regardless of the method or the area. Because the recharge potential on Nantucket is so high (runoff is only 2 percent of the total water balance), the tritium recharge rates probably represent the effective upper limit for ground-water recharge in this region. The recharge-rate values used by Guswa and LeBlanc (1985) and LeBlanc (1984) in their ground-water-flow computer models of Cape Cod are

  2. 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

  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. 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

  6. Identifying and Quantifying Sources of Fall Chinook Salmon Spawning Gravel to the Snake River in Hells Canyon

    NASA Astrophysics Data System (ADS)

    Welcker, C. W.; Burke, M.

    2015-12-01

    The Snake River in Hells Canyon supports a growing population of spawning Fall Chinook Salmon (Oncorhynchus tshawytscha) immediately downstream of the Hells Canyon Complex (HCC) of hydroelectric dams for the last 60 years. The long-term survival of this salmon run depends on the input of spawning gravel (25-150 mm) from local tributaries balancing the losses of spawning gravel through attrition and export out of the reach between the HCC and the Salmon River confluence. We are working to quantify the gravel input of these local tributaries at different time-scales and put this into the context of historical supply and transport. Long-term total sediment production rates of these tributaries estimated through various methods have varied by over 2 orders of magnitude, but we have recently completed 10Be work to constrain these estimates. We are measuring the change in storage of Fall Chinook spawning-size gravel through repeat multibeam echosounder surveys of the riverbed. The limited amount of repeat data collected to date has shown complex patterns of change in the riverbed. One possible driver of this complexity is the episodic and spatially variable nature of sediment inputs from these tributaries. We are attempting to quantify the frequency of the debris flows or floods capable of transporting spawning gravel through digitizing historic imagery of the last 60 years to determine the recurrence interval. We are measuring the magnitude of these events by surveying tributary fans pre and post-event to measure the sediment volume and particle size produced by specific events. These floods and debris flows are driven by extreme rainfall or snowmelt events, so we have also reconstructed historical meteorological conditions to identify the triggering conditions for transport, and identify the areas where snowmelt or rainfall is the more likely trigger. We are currently testing whether the unique bedrock geology of Hells Canyon can be used as a tracer to identify the

  7. The influence of topology on hydraulic conductivity in a sand-and-gravel aquifer.

    PubMed

    Morin, Roger H; LeBlanc, Denis R; Troutman, Brent M

    2010-01-01

    A field experiment consisting of geophysical logging and tracer testing was conducted in a single well that penetrated a sand-and-gravel aquifer at the U.S. Geological Survey Toxic Substances Hydrology research site on Cape Cod, Massachusetts. Geophysical logs and flowmeter/pumping measurements were obtained to estimate vertical profiles of porosity phi, hydraulic conductivity K, temperature, and bulk electrical conductivity under background, freshwater conditions. Saline-tracer fluid was then injected into the well for 2 h and its radial migration into the surrounding deposits was monitored by recording an electromagnetic-induction log every 10 min. The field data are analyzed and interpreted primarily through the use of Archie's (1942) law to investigate the role of topological factors such as pore geometry and connectivity, and grain size and packing configuration in regulating fluid flow through these coarse-grained materials. The logs reveal no significant correlation between K and phi, and imply that groundwater models that link these two properties may not be useful at this site. Rather, it is the distribution and connectivity of the fluid phase as defined by formation factor F, cementation index m, and tortuosity alpha that primarily control the hydraulic conductivity. Results show that F correlates well with K, thereby indicating that induction logs provide qualitative information on the distribution of hydraulic conductivity. A comparison of alpha, which incorporates porosity data, with K produces only a slightly better correlation and further emphasizes the weak influence of the bulk value of varphi on K. PMID:19878327

  8. Water in sand and gravel deposits in McHenry County, Illinois

    SciTech Connect

    Nicholas, J.R.; Krohelski, J.T.

    1984-01-01

    Two general types of sand and gravel occur in McHenry County - unconfined aquifers, which are at or near the land surface, and semiconfined aquifers, which are overlain by one or more till members. Water levels in both types of aquifers are mapped from measurements made in the spring of 1979. The water-level configuration roughly parallels the land surface. Moraines and other topographically high features coincide with ground-water divides of local flow systems. Flow paths from divides to low-lands are relatively short - a few miles or less. Recharge predominates in uplands, whereas discharge predominates in lowlands. Water levels change seasonally in response to variations in recharge and discharge conditions. The highest water levels occur during spring and decline during the rest of the year. Ground water is of the calcium magnesium bicarbonate type and is of acceptable quality for most uses. However, for domestic and some industrial uses, treatment may be required to reduce hardness and to remove iron. Hardness ranged from 130 to 600 milligrams per liter as calcium carbonate, and dissolved iron concentrations ranges from less than 10 to 6200 micrograms per liter. The specific conductance of ground water ranged from 260 to 1170 micromhos per centimeter. Specific conductance exceeded 1000 micromhos per centimeter near Huntley and Hebron. Nitrate concentration was generally less than 0.68 milligrams per liter. 22 refs., 9 figs., 3 tabs.

  9. Effects of HRT and water temperature on nitrogen removal in autotrophic gravel filter.

    PubMed

    Xu, Jing-hang; He, Sheng-bing; Wu, Su-qing; Huang, Jung-Chen; Zhou, Wei-li; Chen, Xue-chu

    2016-03-01

    Organic Carbon added to low ratio of carbon to nitrogen (C/N ratio) wastewater to enhance heterotrophic denitrification performance might lead to higher operating costs and secondary pollution. In this study, sodium thiosulfate (Na2S2O3) was applied as an electron donor for a gravel filter (one kind of constructed wetland) to investigate effects of hydraulic retention time (HRT) and water temperature on the nitrate removal efficiency. The results show that with an HRT of 12 h, the average total nitrogen (TN) removal efficiencies were 91% at 15-20 °C and 18% at 3-6 °C, respectively. When HRT increased to 24 h, the average TN removal increased accordingly to 41% at 3-6 °C, suggesting denitrification performance was improved by extended HRT at low water temperatures. Due to denitrification, 96% of added nitrate nitrogen (NO3(-)-N) was converted to nitrogen gas, with a mean flux of nitrous oxide (N2O) was 0.0268-0.1500 ug m(-2) h(-1), while 98.86% of thiosulfate was gradually converted to sulfate throughout the system. Thus, our results show that the sulfur driven autotrophic denitrification constructed wetland demonstrated an excellent removal efficiency of nitrate for wastewater treatment. The HRT and water temperature proved to be two influencing factors in this constructed wetland treatment system. PMID:26766357

  10. Groundwater Flow and Solute Transport in a Tidally influenced gravel beach in Prince William Sound, Alaska

    NASA Astrophysics Data System (ADS)

    Bobo, A. M.; Boufadel, M. C.; Abdollahi Nasab, A.

    2009-12-01

    We investigated beach hydraulics in a gravel beach on Eleanor Island, Prince William Sound, Alaska that was previously polluted with the Exxon Valdez oil spill in 1989. The beach contains trace amounts of oil such that they don’t affect beach hydraulics. Measurements of water pressure and salinity were analyzed and simulated using the model SUTRA (Saturated-Unsaturated Groundwater Flow and Solute Transport). The results indicated that the beach consists of two layers with contrasting hydraulic properties: an upper layer with a hydraulic conductivity of 10-2 m/s, and a lower layer with a hydraulic conductivity of 10-5 m/s. The presence of the layer of low hydraulic conductivity constrained the fall of the water table resulting in a water table fluctuation that is almost independent of distance from the shoreline. This is unlike previous studies, which occurred in sandy beaches, and where the fluctuation decreased going landward. The water table remained above the layers’ interface, which suggests that the oil did not penetrate the lower layer. This could explain the presence of only tracer amount of oil in the beach. A sudden seaward increase of the slope of the two layers’ interface resulted in water leaving the lower layer near the mid-intertidal zone, and draining to the sea through the upper layer. This created the effect of a hydraulic rupture separating the hydraulics in the seaward portion of the beach from the rest of beach, especially at low tide.

  11. Hydraulic controls of in-stream gravel bar hyporheic exchange and reactions

    NASA Astrophysics Data System (ADS)

    Trauth, Nico; Schmidt, Christian; Vieweg, Michael; Oswald, Sascha E.; Fleckenstein, Jan H.

    2015-04-01

    Hyporheic exchange transports solutes into the subsurface where they can undergo biogeochemical transformations, affecting fluvial water quality and ecology. A three-dimensional numerical model of a natural in-stream gravel bar (20 m × 6 m) is presented. Multiple steady state streamflow is simulated with a computational fluid dynamics code that is sequentially coupled to a reactive transport groundwater model via the hydraulic head distribution at the streambed. Ambient groundwater flow is considered by scenarios of neutral, gaining, and losing conditions. The transformation of oxygen, nitrate, and dissolved organic carbon by aerobic respiration and denitrification in the hyporheic zone are modeled, as is the denitrification of groundwater-borne nitrate when mixed with stream-sourced carbon. In contrast to fully submerged structures, hyporheic exchange flux decreases with increasing stream discharge, due to decreasing hydraulic head gradients across the partially submerged structure. Hyporheic residence time distributions are skewed in the log-space with medians of up to 8 h and shift to symmetric distributions with increasing level of submergence. Solute turnover is mainly controlled by residence times and the extent of the hyporheic exchange flow, which defines the potential reaction area. Although streamflow is the primary driver of hyporheic exchange, its impact on hyporheic exchange flux, residence times, and solute turnover is small, as these quantities exponentially decrease under losing and gaining conditions. Hence, highest reaction potential exists under neutral conditions, when the capacity for denitrification in the partially submerged structure can be orders of magnitude higher than in fully submerged structures.

  12. Geologie study off gravels of the Agua Fria River, Phoenix, AZ

    USGS Publications Warehouse

    Langer, W.H.; Dewitt, E.; Adams, D.T.; O'Briens, T.

    2010-01-01

    The annual consumption of sand and gravel aggregate in 2006 in the Phoenix, AZ metropolitan area was about 76 Mt (84 million st) (USGS, 2009), or about 18 t (20 st) per capita. Quaternary alluvial deposits in the modern stream channel of the Agua Fria River west of Phoenix are mined and processed to provide some of this aggregate to the greater Phoenix area. The Agua Fria drainage basin (Fig. 1) is characterized by rugged mountains with high elevations and steep stream gradients in the north, and by broad alluvial filled basins separated by elongated faultblock mountain ranges in the south. The Agua Fria River, the basin’s main drainage, flows south from Prescott, AZ and west of Phoenix to the Gila River. The Waddel Dam impounds Lake Pleasant and greatly limits the flow of the Agua Fria River south of the lake. The southern portion of the watershed, south of Lake Pleasant, opens out into a broad valley where the river flows through urban and agricultural lands to its confluence with the Gila River, a tributary of the Colorado River.

  13. 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

  14. 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.

  15. 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.

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

    USGS Publications Warehouse

    Buffington, J.M.; Montgomery, D.R.

    1999-01-01

    Using previously published data from flume studies, we test a new approach for quantifying the effects of sediment supply (i.e., bed material supply) on surface grain size of equilibrium gravel channels. Textural response to sediment supply is evaluated relative to a theoretical prediction of competent median grain size (D'50). We find that surface median grain size (D50) varies inversely with sediment supply rate and systematically approaches the competent value (D'50) at low equilibrium transport rates. Furthermore, equilibrium transport rate is a power function of the difference between applied and critical shear stresses and is therefore a power function of the difference between competent and observed median grain sizes (D'50 and D50). Consequently, we propose that the difference between predicted and observed median grain sizes can be used to determine sediment supply rate in equilibrium channels. Our analysis framework collapses data from different studies toward a single relationship between sediment supply rate and surface grain size. While the approach appears promising, we caution that it has been tested only on a limited set of laboratory data and a narrow range of channel conditions.

  17. Local sorting, bend curvature, and particle mobility in meandering gravel bed rivers

    NASA Astrophysics Data System (ADS)

    Clayton, Jordan A.

    2010-02-01

    Hydraulic, grain scale sorting of mixed bed sediment influences the mobility of grains in discrete areas of river channels. To assess this effect, local values of surface grain size sorting were compared with measurements of bed load at corresponding locations in a bend of the Colorado River in Rocky Mountain National Park (RMNP), and the distribution of local Shields stress through the reach was derived from a two-dimensional flow model. With decreasing degrees of local sorting, the relative mobility of the fine- and coarse-size fractions of the load appeared to decrease and increase, respectively. Furthermore, back-calculated critical Shields stress values for sediment entrainment decreased with values of local sorting, particularly for the upstream portion of the reach where particles were more poorly sorted and coarse grains had higher relative exposure. To evaluate the pervasiveness of these and other patterns of sorting in gravel rivers, detailed field measurements of channel topography and surface grain size (317 pebble counts) were obtained for seven additional reaches of differing curvature (radius of curvature/width from 1 to 28) near the headwaters of the Colorado and Fall rivers in RMNP. Moderately curved and tight bends (radius of curvature/width ≤ 7) were significantly better sorted than comparatively straight reaches. Values of local sorting decreased with distance downstream for the majority of curved channels, reflecting a reduction in the standard deviation of surface grain sizes toward the lower end of the reach; this effect increased slightly with bend sharpness.

  18. Niche-Partitioning of Edaphic Microbial Communities in the Namib Desert Gravel Plain Fairy Circles

    PubMed Central

    Ramond, Jean-Baptiste; Pienaar, Annelize; Armstrong, Alacia; Seely, Mary; Cowan, Don A.

    2014-01-01

    Endemic to the Namib Desert, Fairy Circles (FCs) are vegetation-free circular patterns surrounded and delineated by grass species. Since first reported the 1970's, many theories have been proposed to explain their appearance, but none provide a fully satisfactory explanation of their origin(s) and/or causative agent(s). In this study, we have evaluated an early hypothesis stating that edaphic microorganisms could be involved in their formation and/or maintenance. Surface soils (0–5cm) from three different zones (FC center, FC margin and external, grass-covered soils) of five independent FCs were collected in April 2013 in the Namib Desert gravel plains. T-RFLP fingerprinting of the bacterial (16S rRNA gene) and fungal (ITS region) communities, in parallel with two-way crossed ANOSIM, showed that FC communities were significantly different to those of external control vegetated soil and that each FC was also characterized by significantly different communities. Intra-FC communities (margin and centre) presented higher variability than the controls. Together, these results provide clear evidence that edaphic microorganisms are involved in the Namib Desert FC phenomenon. However, we are, as yet, unable to confirm whether bacteria and/or fungi communities are responsible for the appearance and development of FCs or are a general consequence of the presence of the grass-free circles. PMID:25279514

  19. Efficacy of a vacuum benthos sampler for collecting demersal fish eggs from gravel substratum

    USGS Publications Warehouse

    Ruetz, C. R., III; Jennings, C.A.

    1997-01-01

    We used two densities of eggs (low=900 eggs/m2; high=5100 eggs/m2) in laboratory experiments to estimate the recovery efficiency of the Brown benthos sampler for collecting fish eggs from gravel substrate and to determine if differences (e.g., 5-fold) in egg density in the substratum could be detected with the sampler. The mean egg recovery efficiency of the sampler in the low and high density treatments was 30% (SE=8.7) and 35% (SE=3.8), respectively. The difference between the treatment means was not significant. Therefore, data from the two treatments were pooled and used to estimate the recovery efficiency of the sampler (32.7%, SE=4.4). However, we were able to detect a 5?? difference in the number of eggs collected with the sampler between the two treatments. Our estimate of the recovery efficiency of the sampler for collecting fish eggs was less than those reported for the sampler's efficiency for collecting benthic macroinvertebrates. The low recovery efficiency of the sampler for collecting fish eggs does not lessen the utility of the device. Rather, ecologists planning to use the sampler must estimate the recovery efficiency of target fauna, especially if density estimates are to be calculated, because recovery efficiency probably is less than 100%. ?? Munksgaard, 1997.

  20. 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

  1. Comparison of alternative remediation technologies for recycled gravel contaminated with heavy metals.

    PubMed

    Gao, Xiaofeng; Gu, Yilu; Huang, Sheng; Zhen, Guangyin; Deng, Guannan; Xie, Tian; Zhao, Youcai

    2015-11-01

    To evaluate the effects of different remediation methods on heavy metals contaminated recycled gravel, three immobilization agents (monopotassium phosphate, lime, nano-iron) and two mobilization agents (glyphosate, humic acid (HA)) were studied and compared. Results indicated that nano-iron powder was found to be more effective to immobilize Zn, Cu, Pb and Cd. Meanwhile, glyphosate presents a higher mobilization effect than HA with removal rates of about 66.7% for Cd, more than 80% for Cr, Cu and Zn, and the highest removal percentage of 85.9% for Cr. After the mobilization by glyphosate, the leaching rates of Zn, Cu and Cr were about 0.8%, and below 0.2% for Pb and Cd. The leaching rates after nano-iron powder treatment were 1.18% for Zn, 0.96% for Cr, 0.61% for Cu, 0.45% for Pb and Cd not detected. The formation and disappearance of metal (Zn/Cu/Cr/Pb/Cd) compounds were firmly confirmed through X-ray diffraction and scanning electron microscopy analyses on crystalline phases and morphological surface structures. PMID:26416851

  2. An Introduction to Using Surface Geophysics to Characterize Sand and Gravel Deposits

    USGS Publications Warehouse

    Lucius, Jeffrey E.; Langer, William H.; Ellefsen, Karl J.

    2006-01-01

    This report is an introduction to surface geophysical techniques that aggregate producers can use to characterize known deposits of sand and gravel. Five well-established and well-tested geophysical methods are presented: seismic refraction and reflection, resistivity, ground penetrating radar, time-domain electromagnetism, and frequency-domain electromagnetism. Depending on site conditions and the selected method(s), geophysical surveys can provide information concerning aerial extent and thickness of the deposit, thickness of overburden, depth to the water table, critical geologic contacts, and location and correlation of geologic features. In addition, geophysical surveys can be conducted prior to intensive drilling to help locate auger or drill holes, reduce the number of drill holes required, calculate stripping ratios to help manage mining costs, and provide continuity between sampling sites to upgrade the confidence of reserve calculations from probable reserves to proved reserves. Perhaps the greatest value of geophysics to aggregate producers may be the speed of data acquisition, reduced overall costs, and improved subsurface characterization.

  3. An Introduction to Using Surface Geophysics to Characterize Sand and Gravel Deposits

    USGS Publications Warehouse

    Lucius, Jeffrey E.; Langer, William H.; Ellefsen, Karl J.

    2007-01-01

    This report is an introduction to surface geophysical techniques that aggregate producers can use to characterize known deposits of sand and gravel. Five well-established and well-tested geophysical methods are presented: seismic refraction and reflection, resistivity, ground penetrating radar, time-domain electromagnetism, and frequency-domain electromagnetism. Depending on site conditions and the selected method(s), geophysical surveys can provide information concerning areal extent and thickness of the deposit, thickness of overburden, depth to the water table, critical geologic contacts, and location and correlation of geologic features. In addition, geophysical surveys can be conducted prior to intensive drilling to help locate auger or drill holes, reduce the number of drill holes required, calculate stripping ratios to help manage mining costs, and provide continuity between sampling sites to upgrade the confidence of reserve calculations from probable reserves to proved reserves. Perhaps the greatest value of geophysics to aggregate producers may be the speed of data acquisition, reduced overall costs, and improved subsurface characterization.

  4. Performance evaluation and modelling studies of gravel--coir fibre--sand multimedia stormwater filter.

    PubMed

    Samuel, Manoj P; Senthilvel, S; Tamilmani, D; Mathew, A C

    2012-09-01

    A horizontal flow multimedia stormwater filter was developed and tested for hydraulic efficiency and pollutant removal efficiency. Gravel, coconut (Cocos nucifera) fibre and sand were selected as the media and filled in 1:1:1 proportion. A fabric screen made up of woven sisal hemp was used to separate the media. The adsorption behaviour of coir fibre was determined in a series of column and batch studies and the corresponding isotherms were developed. The hydraulic efficiency of the filter showed a diminishing trend as the sediment level in inflow increased. The filter exhibited 100% sediment removal at lower sediment concentrations in inflow water (>6 g L(-1)). The filter could remove NO3(-), SO4(2-) and total solids (TS) effectively. Removal percentages of Mg(2+) and Na(+) were also found to be good. Similar results were obtained from a field evaluation study. Studies were also conducted to determine the pattern of silt and sediment deposition inside the filter body. The effects of residence time and rate of flow on removal percentages of NO3(-) and TS were also investigated out. In addition, a multiple regression equation that mathematically represents the filtration process was developed. Based on estimated annual costs and returns, all financial viability criteria (internal rate of return, net present value and benefit-cost ratio) were found favourable and affordable to farmers for investment in the developed filtration system. The model MUSIC was calibrated and validated for field conditions with respect to the developed stormwater filter. PMID:23240200

  5. Study of hydraulic parameters in heterogeneous gravel beds: Constructed wetland in Nowa Słupia (Poland)

    NASA Astrophysics Data System (ADS)

    Małoszewski, Piotr; Wachniew, Przemysław; Czupryński, Piotr

    2006-12-01

    SummaryCombined use of tracers and mathematical modelling for evaluation of hydraulic characteristics of constructed wetlands is presented for the subsurface-flow system with Phragmites australis in Nowa Słupia (Poland). Instantaneously injected bromide and tritium tracers were used to obtain residence time distributions of wastewaters in three parallel inhomogeneous gravel cells of the wetland. The multi flow dispersion model, which assumes the existence of several flow-paths with different hydraulic properties was developed using the respective parallel combination of analytical solutions of the one-dimensional advection-dispersion equation. The model was used successfully to fit the experimental tracer breakthrough curves. Different flow components were identified and wastewater volumes, water-saturated porosity, mean wastewater travel times, longitudinal dispersivities as well as hydraulic conductivity of wetland cells were derived from model parameters. The variation in flow components and apparent hydraulic characteristics among wetland cells relate to the improper design and maintenance of the wetland. The single fissure dispersion model, which assumes possible diffusion of tracers into the zones with stagnant water during convective-dispersive flow through the mobile zone is adopted to the research conditions and used to model the TBC-s for one cell. The results show that this model can be calibrated with the satisfactory accuracy in that cell but yields unacceptable values of some parameters.

  6. Hydrogeology and water quality of significant sand and gravel aquifers in parts of Androscoggin, Cumberland, Franklin, Kennebec, Lincoln, Oxford, Sagadahoc, and Somerset Counties, Maine: Sand and gravel aquifer maps 10, 11, 16, 17 and 32

    SciTech Connect

    Tepper, D.H.; Williams, J.S.; Tolman, A.L.; Prescott, G.C.

    1985-01-01

    A reconnaissance level geohydrologic study was made of 2,408 sq mi in Androscoggin, Cumberland, Franklin, Kennebec, Lincoln, Oxford, Sagadahoc and Somerset Counties in Maine. This area is included in Maps 10, 11, 16, 17, and 32 of the Sand and Gravel Aquifer Map Series published by the Maine Geological Survey. The significant sand and gravel aquifers, consist of glacial ice-contact and outwash deposits which occur primarily in the valleys of the major rivers and along their tributaries. Significant aquifers comprise almost 109 sq mi, but yields that exceed 50 gal/min are estimated to be available within only 21% of this area. Typically, the water table is within 20 ft of the land surface. Based on seismic data, the great known depth to bedrock is 340 ft. The regional groundwater quality has the following characteristics: It is slightly acidic to slightly basic; calcium and sodium are the most abundant cations; bicarbonate is the most abundant anion; and the water is soft. In some localities concentrations of iron and manganese are high enough to limit use of the water without treatment. Sixty-six sites, including 32 solid waste facilities and 18 salt-storage lots were identified as potential sources of groundwater contamination to the sand and gravel aquifers in the study area. 79 refs., 11 figs., 9 tabs.

  7. High Variance within Salmonid Spawning Gravels at Restoration Sites Creates More Suitable Habitat within the Hyporheic Zone

    NASA Astrophysics Data System (ADS)

    Janes, M. K.; Heffernan, J. E.; Rosenberry, J. W.; Horner, T.

    2012-12-01

    The Lower American River has historically provided natural spawning habitat for approximately one third of Northern California's salmon population. However, since the construction of Folsom and Nimbus Dams, downstream reaches have become sediment starved and periodic high outflow from the dam has caused channel armoring and incision, thereby degrading the natural spawning habitat. Restoration work on spawning sites in the Lower American River has consisted primarily of importing gravel to create riffles during periods of moderate flow. This is an effort to mitigate armoring of the riverbed and to rehabilitate salmonid spawning habitat by providing suitable grain size for all stages of spawning (redd construction, incubation, and emergence). Since restoration activities began, all rehabilitated sites have not been equally used for spawning. This study attempts to examine and compare the physical properties of each site in order to ascertain which characteristics create more suitable rehabilitated habitat. To do this, we compared restored areas to pre-restoration conditions through the assessment of three main aspects of the restored spawning habitat; grain size and its natural mobility, water flow in the surface and subsurface, and intragravel water quality. We found that some augmentation sites are more heterogeneous than others, and this correlates with higher spawning use. Most spawning was at fin height, and salmonids tend to use sites with higher depth variance (surface features) and higher variance in flow directions and velocities. With time, salmonids alter the spawning sites, creating small ridges and valleys perpendicular to flow. This creates more variable subsurface flow and generates hyporheic flow through the new gravel. This may have an effect on spawning as the more seasoned additions have a higher frequency of spawning than the newer augmentations. In order to efficiently rehabilitate a site and expedite the "seasoning process", creating variance

  8. Seed retention by pioneer trees enhances plant diversity resilience on gravel bars: Observations from the river Allier, France

    NASA Astrophysics Data System (ADS)

    Corenblit, Dov; Vidal, Vincent; Cabanis, Manon; Steiger, Johannes; Garófano-Gómez, Virginia; Garreau, Alexandre; Hortobágyi, Borbála; Otto, Thierry; Roussel, Erwan; Voldoire, Olivier

    2016-07-01

    Pioneer riparian trees which establish in river active tracts on gravel bars enhance fine sediment retention during high flows within their stands and in their lee side, forming obstacle marks. Fine sediment retention can be accompanied by deposition of seeds transported by water dispersal, i.e. by hydrochory. We tested the hypothesis that pioneer riparian trees significantly control seed deposition on gravel bars by forming sediment obstacle marks. We described the seed bank structure and compared samples collected from obstacle marks and bare coarse-grained bar surfaces. At the surface (at 2 cm depth), seed abundance (N) and richness (S) (expressed as mean ± sd) were significantly higher in areas directly affected by riparian trees, i.e. obstacle marks, (N: 693 ± 391; S: 17 ± 3) than in bare surfaces (N: 334 ± 371; S: 13 ± 5). Surface and sub-surface (at 20 cm depth) samples were also significantly different, with the sub-surface samples almost devoid of seeds (respectively N: 514 ± 413; S: 15 ± 5 and N: 3 ± 6; S: 1 ± 2). These results suggest a biogeomorphic feedback between sediment and associated seed retention mediated by hydrochory, vegetation growth and local seed dispersal mediated by barochory. Such feedback may improve plant diversity resilience on gravel alluvial bars of high-energy rivers.

  9. Hydrogeology and flow of water in a sand and gravel aquifer contaminated by wood-preserving compounds, Pensacola, Florida

    USGS Publications Warehouse

    Franks, B.J.

    1988-01-01

    The sand and gravel aquifer in southern Escambia County, Florida , is a typical surficial aquifer composed of quartz sands and gravels interbedded locally with silts and clays. Problems of groundwater contamination from leaking surface impoundments are common in surficial aquifers and are a subject of increasing concern and attention. A potentially widespread contamination problem involves organic chemicals from wood-preserving processes. Because creosote is the most extensively used industrial preservative in the United States, an abandoned wood-treatment plant near Pensacola was chosen for investigation. This report describes the hydrogeology and groundwater flow system of the sand and gravel aquifer near the plant. A three-dimensional simulation of groundwater flow in the aquifer was evaluated under steady-state conditions. The model was calibrated on the basis of observed water levels from January 1986. Calibration criteria included reproducing all water levels within the accuracy of the data (one-half contour interval in most cases). Sensitivity analysis showed that the simulations were most sensitive to recharge and vertical leakance of the confining units between layers 1 and 2, and relatively insensitive to changes in hydraulic conductivity and transmissivity and to other changes in vertical leakance. Applications of the results of the calibrated flow model in evaluation of solute transport may require further discretization of the contaminated area, including more sublayers, than were needed for calibration of the groundwater flow system itself. (USGS)

  10. A study of the influence of a gravel subslab layer on radon entry rate using two basement structures

    SciTech Connect

    Robinson, A.L.; Sextro, R.G.; Fisk, W.J.; Garbesi, K.; Wooley, J.; Wollenberg, H.A.

    1993-01-01

    In buildings with elevated radon concentrations, the dominant transport mechanism of radon is advective flow of soil gas into the building substructure. However, the building-soil system is often complex, making detailed studies of the radon source term difficult. In order to examine radon entry into buildings, the authors have constructed two room-size, precisely-fabricated basement structures at a site with relatively homogeneous, moderately permeable soil. The basements are identical except that one lies directly on native soil whereas the other lies on a high permeability aggregate layer. The soil pressure field and radon entry rate have been measured for different basement pressures and environmental conditions. The subslab gravel layer greatly enhances the advective entry of radon into the structure; when the structures are depressurized, the radon entry rate into the structure with the subslab gravel layer is more than a factor of 3 times the radon entry rate into the other structure for the same depressurization. The gravel subslab layer also spreads the pressure field around the structure, extending the field of influence of the structure and the region from which it draws radon.

  11. Fingerprints of environmental stressors in three selected Slovenian gravel-bed rivers: geochemical and isotopic approach

    NASA Astrophysics Data System (ADS)

    Kanduč, Tjaša; Kocman, David; Debeljak, Barbara; Mori, Nataša

    2016-04-01

    Rivers are severely impacted by a range of simultaneous processes including water pollution, flow and channel alteration, over-fishing, invasive species and climate change. Systematic studies of river water geochemistry provide important information on chemical weathering of bedrock/soil and natural anthropogenic processes that may control the dissolved chemical loads, while the isotopic studies of biological components of river systems (macrophytes, periphyton, heterotrophic biofilm, invertebrates, fish) contribute to the understanding how the system response to human impacts by means of functional response. In this contribution, insights in the fingerprints of various environmental stressors in three gravel-bed rivers (River Kamni\\vska Bistrica, River Idrijca and River Sava) in Slovenia, using geochemical and stable isotope approach are discussed. Gravel bed of all three rivers investigated is composed of carbonates and clastic rocks. The Sava and Kamni\\vska Bistrica Rivers have alpine high mountain snow-rain regime. The Idrijca River is a boundary river between the Adriatic and Black Sea catchments and has rain-snow discharge regime with torrential character. Geochemical methods (ICP-OES, IC, total alkalinity after Gran) and isotope mass - spectrometric methods (isotopic composition of dissolved inorganic carbon, particulate organic carbon and isotopic composition of carbon in carbonates) were used to evaluate biogeochemical processes in rivers. Isotopic composition of carbon and nitrogen of the moss Fontinalis antipyretica (the whole vegetative shoot) and isotopic composition of carbon of heterotrophic biofilm was also analyzed in order to better understand the fluxes and fractionation of carbon and nitrogen across trophic levels. Geochemical composition of all investigated rivers is HCO3‑-Ca2+-Mg2+ with different Mg2+/Ca2+ ratios as follows: around 0.33 for Kamni\\vska Bistrica and River Sava in Slovenia and above 0.75 for River Idrijca. In the Kamni

  12. Interactions between bar dynamics and herbaceous vegetation in gravel bed rivers: numerical simulations using BASEMENT

    NASA Astrophysics Data System (ADS)

    Siviglia, Annunziato; Tettamanti, Stefano; Bertoldi, Walter; Toffolon, Marco; Vetsch, David; Francalanci, Simona

    2014-05-01

    A new 2D morphodynamic model for gravel bed rivers have been used to investigate the interaction between alternate bar dynamics and herbaceous vegetation. In particular, bed topography evolution has been coupled with the growth of vegetation, included as a function of the access to ground water. Numerical simulations were performed using the code BASEMENT (Vetsch et al., 2013), with the addition of a new submodel, dealing with the numerical description of the vegetation. The vegetation was allowed to grow during the dry season on exposed areas, and the vertical distribution of peak biomass was modeled as a function of the bed elevation, using a simple analytical formulation, following Marani et al. (2013). Flow resistance was divided into a component exerted by the bed and a component exerted by vegetation (Crosato and Saleh, 2010; Li and Millar, 2011); in this way we reproduced both the decrease in bed shear stress, reducing the sediment transport capacity of the flow within the plants, and the increase in hydraulic resistance, reducing flow velocity. The model was applied to a hypothetical case study, with grain size, longitudinal slope, and hydrological regime similar to that of the Magra River (Italy). A straight river reach, 125 m wide and 20 km long was simulated. Starting from an initially flat configuration, the river developed its own bar morphology, under steady formative conditions. After reaching a dynamic equilibrium, we allowed the vegetation to grow and interact with the morphodynamic evolution, reproducing a sequence of floods and growing seasons at low flow. We assumed that vegetation can be uprooted only if the bed shear stress exceeds a fixed threshold. Different scenarios were examined, varying the effect of vegetation in terms of increased resistance and threshold for uprooting (i.e. added sediment cohesion). Preliminary results confirmed that the herbaceous vegetation has a stabilizing effect on river morphology. As the density and strength of

  13. Assessment of Large Wood budget in the gravel-bed Piave River: first attempt

    NASA Astrophysics Data System (ADS)

    Tonon, Alessia; Picco, Lorenzo; Ravazzolo, Diego; Aristide Lenzi, Mario

    2015-04-01

    During the last decades, the dynamics of large wood (LW) in rivers were analyzed to consider and define the LW budget. The space-time variations of LW amount results from the differences among input (e.g. fluvial transport, lateral recruitment) and output (e.g. fluvial transport, overbank deposition, natural chronic dead) of LW along a riverine environment. Different methodologies were applied in several fluvial environments, however in large river systems characterized by complex LW dynamics, the processes are still poor quantified. Aim of this contribution is to perform a LW budget estimation over the short period, assessing the effect of an over bankfull flood (Q=1039 m3 s-1; R.I=3.5 years). The research was carried out along a 1 km-long reach (around 15 ha) located into the middle course of the large gravel-bed Piave River (North East of Italy). The LW budget has been defined considering the recruitment through bank erosion and the fluvial transport of LW into and out of the study reach. The former factor was achieved integrating field data on riparian vegetation with the monitoring of riverbanks with a Differential Global Positioning System (DGPS). The latter was obtained detecting all LW elements (diameter ≥ 0.10 m and/or length ≥ 1 m) stored along the study reach, before and after the flood. For each LW the GPS position was recorded and a numbered tag was installed with the addition of colored paint to permit a rapid post-event recovery. Preliminary results indicate that, along the study area, the floating transport of LW is one of the most significant processes able to modify the amount of LW deposited along a riverine system. In fact, considering the input of LW, the 99.4 % (102 m3 km-1) comes from upstream due to floating, whereas the 0.6% (0.17 m3 km-1) was recruited through bank erosion. Analyzing the output, 94.3% (40.26 m3 km-1) of LW was transported downstream of the study area, whereas only the 5.7 % (2.43 m3 km-1) of LW was involved in the

  14. Sewage plume in a sand and gravel aquifer, Cape Cod, Massachusetts

    USGS Publications Warehouse

    LeBlanc, Denis R.

    1984-01-01

    Secondarily treated domestic sewage has been disposed of on surface sand beds at the sewage treatment facility at Otis Air Force Base, Massachusetts, since 1936. Infiltration of the sewage through the sand beds into the underlying unconfined sand and gravel aquifer has resulted in a plume of sewage-contaminated ground water that is 2,500 to 3,500 feet wide, 75 feet thick, and more than 11,000 feet long. The plume extends south and southwest of the sand beds in the same direction as the regional flow of ground water, and is overlain by 20 to 50 feet of ground water derived from precipitation that recharges the aquifer. The bottom of the plume generally coincides with the contact between the permeable sand and gravel and underlying finer grained sediments. The distributions in the aquifer of specific conductance, temperature, boron, chloride, sodium, phosphorus, nitrogen (total of all species), ammonia, nitrate, dissolved oxygen, and detergents are used to delineate the plume. In ground water outside the plume, the detergent concentration is less than 0.1 milligrams per liter as MBAS (methylene blue active substances), the ammonia-nitrogen concentration is less than 0.1 milligrams per liter, the boron concentration is less than 50 micrograms per liter, and specific conductance is less than 80 mircromhos per centimeter. In the center of the plume, detergent concentrations as high as 2.6 milligrams per liter as MBAS, ammonia-nitrogen concentrations as high as 20 milligrams per liter, boron concentrations as high as 400 micrograms per liter, and specific conductance as high as 405 micromhos per centimeter were measured. Chloride, sodium, and boron are transported by the southward-flowing ground water without significant retardation, and seem to be diluted only by hydrodynamic dispersion. The movement of phosphorus is greatly restricted by sorption. Phosphorus concentrations do not exceed 0.05 milligrams per liter farther than 2,500 feet from the sand beds. Detergent

  15. An experimental analysis of bed load transport in gravel-bed braided rivers with high grain Reynolds numbers

    NASA Astrophysics Data System (ADS)

    De Vincenzo, Annamaria; Brancati, Francesco; Pannone, Marilena

    2016-08-01

    Laboratory experiments were performed with nearly uniform fluvial gravel (D50=9 mm, D10=5 mm and D90=13 mm) to analyse the relationship between stream power and bed load transport rate in gravel-bed braided rivers at high grain Reynolds numbers. The values of the unit-width dimensionless bed-load rate qb* and unit-width dimensionless stream power ω* were evaluated in equilibrium conditions based on ten different experimental runs. Then, they were plotted along with values obtained during particularly representative field studies documented in the literature, and a regression law was derived. For comparison, a regression analysis was performed using the data obtained from laboratory experiments characterized by smaller grain sizes and, therefore, referring to relatively low grain Reynolds numbers. A numerical integration of Exner's equation was performed to reconstruct the local and time-dependent functional dependence of qb* and ω*. The results led to the following conclusions: 1) At equilibrium, the reach-averaged bed load transport rate is related to the reach-averaged stream power by different regression laws at high and low grain Reynolds numbers. Additionally, the transition from bed to suspended load transport is accelerated by low Re*, with the corresponding bed load discharge increasing with stream power at a lower, linear rate. 2) When tested against the gravel laboratory measurements, the high Re* power law derived in the present study performs considerably better than do previous formulas. 3) The longitudinal variability of the section-averaged equilibrium stream power is much more pronounced than that characterizing the bed load rate, at least for high Re*. Thus, the stream power and its local-scale heterogeneity seem to be directly responsible for transverse sediment re-distribution and, ultimately, for the determination of the spatial and temporal scales that characterize the gravel bedforms. 4) Finally, the stochastic interpretation of the wetted

  16. Variation in surface bed material along a mountain river modified by gravel extraction and channelization, the Czarny Dunajec, Polish Carpathians

    NASA Astrophysics Data System (ADS)

    Zawiejska, Joanna; Wyżga, Bartłomiej; Radecki-Pawlik, Artur

    2015-02-01

    Longitudinal changes in the grain size of bar sediments of the mountain Czarny Dunajec, southern Poland, were investigated to determine the impact of human activity in the river on depositional conditions in its channel. The grain size of surface bed material was established on 47 gravel bars along an 18-km-long river reach without tributaries, in which some sections were modified over the past few decades by channelization or gravel extraction and the resultant channel incision. A downstream fining trend of bar sediments was determined from samples taken at the sites with close-to-average river width and a vertically stable channel and used as reference for the other samples. In the deeply incised, upper part of the reach, bar gravels are markedly coarser than the reference grain size. In the narrow, channelized section in the middle part of the reach, bar sediments exhibit better-than-average sorting and change from coarser gradation to one similar to that of the reference grain size along the section. In the wide, multithread channel in the lower part of the reach, bar gravels are distinctly finer than the reference grain size. A similar pattern of downstream variation in the study reach was determined for the river competence on the basis of critical bed shear stress required to entrain D95 particles of the bar gravels. The extraction of larger particles from the channel bed in the upper part of the study reach facilitated entrainment of exposed finer grains, hence inducing rapid bed degradation. At the same time, the concentration of flood flows in an increasingly narrow and deep channel must have increased their competence, enabling a delivery of the coarse particles previously typical of the upstream reach. The middle section has been channelized to prevent sediment delivery to a downstream-located dam reservoir. However, it actually operates as a conveyor belt, transferring downstream the bed material flushed out from the upstream, incising river section

  17. Changes to channel sediments resulting from complex human impacts in a gravel-bed river, Polish Carpathians

    NASA Astrophysics Data System (ADS)

    Zawiejska, Joanna; Wyżga, Bartłomiej; Hajdukiewicz, Hanna; Radecki-Pawlik, Artur; Mikuś, Paweł

    2016-04-01

    During the second half of the twentieth century, many sections of the Czarny Dunajec River, Polish Carpathians, were considerably modified by channelization as well as gravel-mining and the resultant channel incision (up to 3.5 m). This paper examines changes to the longitudinal pattern of grain size and sorting of bed material in an 18-km-long river reach. Surface bed-material grain size was established on 47 gravel bars and compared with a reference downstream fining trend of bar sediments derived from the sites with average river width and a vertically stable channel. Contrary to expectations, the extraction of cobbles from the channel bed in the upper part of the study reach, conducted in the past decades, has resulted in the marked coarsening of bed material in this river section. The extraction facilitated entrainment of exposed finer grains and has led to rapid bed degradation, whereas the concentration of flood flows in the increasingly deep and narrow channel has increased their competence and enabled a delivery of the coarse particles previously typical of the upstream reach. The middle section of the study reach, channelized to prevent sediment delivery to a downstream reservoir, now transfers the bed material flushed out from the incising upstream section. With considerably increased transport capacity of the river and with sediment delivery from bank erosion eliminated by bank reinforcements, bar sediments in the channelized section are typified by increased size of the finer fraction and better-than-average sorting. In the wide, multi-thread channel in the lower part of the reach, low unit stream power and high channel-form roughness facilitate sediment deposition and are reflected in relatively fine grades of bar gravels. The study showed that selective extraction of larger particles from the channel bed leads to channel incision at and upstream of the mining site. However, unlike bulk gravel mining, selective extraction does not result in sediment

  18. Multi-scale investigation of fine-sediment ingress in gravel-bed rivers using experiments and numerical modelling

    NASA Astrophysics Data System (ADS)

    Lamparter, Gabriele; Collins, Adrian; Nicholas, Andrew

    2015-04-01

    Increased suspended sediment loads in gravel-bed rivers, potentially leading to clogging of the pores in the river bed, is a problem acknowledged since at least the 1980s. Early research was concerned with declining salmonid production along the North American Pacific coast due to siltation processes. Since then, research has expanded and includes a wider geographical and ecological coverage. Despite this long history of research into gravel-clogging by fine sediment, the relationship between enhanced suspended sediment loads and sediment ingress is still poorly quantified. The research presented here seeks to address this gap and has a two scale approach to improve the quantification of fine-sediment ingress into river gravels under a range of flow, fine sediment and gravel framework conditions. Laboratory scale flume experiments mimicking natural conditions were used to measure flow and the character of fine sediment both above and ingressing into custom-made basket traps. At a larger scale, the same basket traps were installed in a field setting (the gravel-bed River Culm in South-West England) in three river reaches, in conjunction with continuous monitoring of suspended sediment concentration and flow discharge (to estimate sediment loads). The data were evaluated with regards to the Krone formulation for deposition (Krone, 1962), an equation generally believed to include the main physical determinants driving fine-sediment deposition. The formulation states that rise in suspended sediment concentration, settling velocity and also decline of flow velocity or bed shear stress all lead to an increase in suspended sediment deposition. This evaluation was achieved by setting up a numerical model, which was initially applied to the flume experiments and subsequently up-scaled to the field scale. Data generated by both the flume and the field experiments do not agree well with the predictions of the Krone formulations. This agreement was especially weak for fine

  19. Entrainment of riparian gravel and cobbles in an alluvial reach of a regulated canyon river

    USGS Publications Warehouse

    Elliotp, J.G.; Hammack, L.A.

    2000-01-01

    Many canyon rivers have channels and riparian zones composed of alluvial materials and these reaches, dominated by fluvial processes, are sensitive to alterations in streamflow regime. Prior to reservoir construction in the mid-1960s, banks and bars in alluvial reaches of the Gunnison River in the Black Canyon National Monument, Colorado, USA, periodically were reworked and cleared of riparian vegetation by mainstem floods. Recent interest in maintaining near-natural conditions in the Black Canyon using reservoir releases has created a need to estimate sediment-entraining discharges for a variety of geomorphic surfaces composed of sediment ranging in size from gravel to small boulders. Sediment entrainment potential was studied at eight cross-sections in an alluvial reach of the Gunnison River in the Black Canyon in 1994 and 1995. A one-dimensional water-surface profile model was used to estimate water-surface elevations, flow depths, and hydraulic conditions on selected alluvial surfaces for discharges ranging from 57 to 570 m3/s. Onsite observations before and after a flood of 270 m3/s confirmed sediment entrainment on several surfaces inundated by the flood. Selective entrainment of all but the largest particle sizes on the surface occurred at some locations. Physical evidence of sediment entrainment, or absence of sediment entrainment, on inundated surfaces generally was consistent with critical shear stresses estimated with a dimensionless critical shear stress of 0.030. Sediment-entrainment potential over a range of discharges was summarized by the ratio of the local boundary shear stress to the critical shear stress for d50, given hydraulic geometry and sediment-size characteristics. Differing entrainment potential for similar geomorphic surfaces indicates that estimation of minimum streamflow requirements based on sediment mobility is site-specific and that there is no unique streamflow that will initiate movement of d50 at every geomorphically similar

  20. Geomorphic effects of wood quantity and characteristics in three Italian gravel-bed rivers

    NASA Astrophysics Data System (ADS)

    Ravazzolo, D.; Mao, L.; Picco, L.; Sitzia, T.; Lenzi, M. A.

    2015-10-01

    In-channel wood is a fundamental component of the riverine system. Its nature, abundance, and distribution as well as the role of wood in trapping sediment have been reported by many authors. However, a lack of knowledge still exists on how the geomorphic effects, quantity, and characteristics of in-channel wood may be altered by different human pressures. For this reason, in-channel wood was surveyed in the Brenta, Piave, and Tagliamento gravel-bed rivers (northeastern Italy), which are altered by different degrees of human pressures. Both single pieces of wood (> 0.1 m diameter, and/or > 1 m long) and accumulations of large wood were measured on cross sectional transects within the active channels. Overall, 3430 (8.4, 13.9 and 10.7 elements/ha in the Brenta, Piave, and Tagliamento rivers, respectively) of isolated pieces and 591 (9.8, 15.0, and 11.0 wood accumulations/ha in the Brenta, Piave, and Tagliamento rivers, respectively) accumulations were surveyed in the study sites. In the Brenta and Piave rivers, which feature the greater human pressures, logs appear in a worse state of conservation. In the less disturbed Tagliamento River, the logs appear to be smaller and in a better state of conservation with higher capacity for resprouting. In addition, higher geomorphic interactions were found between wood and sediments in the Tagliamento River. Because of its ability to create geomorphic effects, in-channel wood represents an important source of complexity that can increase habitat diversity in river systems. A better knowledge of the role of human disturbances on the characteristics and abundance of large wood in river systems could help in developing better river management and the practical application of river ecology.

  1. Geomorphic changes resulting from floods in reconfigured gravel-bed river channels in Colorado, USA

    USGS Publications Warehouse

    Elliott, J.G.; Capesius, J.P.

    2009-01-01

    Geomorphic changes in reconfi gured reaches of three Colorado rivers in response to floods in 2005 provide a benchmark for "restoration" assessment. Sedimententrainment potential is expressed as the ratio of the shear stress from the 2 yr, 5 yr, 10 yr, and 2005 floods to the critical shear stress for sediment. Some observed response was explained by the excess of flood shear stress relative to the resisting force of the sediment. Bed-load entrainment in the Uncompahgre River and the North Fork Gunnison River, during 4 and 6 yr floods respectively, resulted in streambed scour, streambed deposition, lateral-bar accretion, and channel migration at various locations. Some constructed boulder and log structures failed because of high rates of bank erosion or bed-material deposition. The Lake Fork showed little or no net change after the 2005 flood; however, this channel had not conveyed floods greater than the 2.5 yr flood since reconfi guration. Channel slope and the 2 yr flood, a surrogate for bankfull discharge, from all three reconfi gured reaches plotted above the Leopold and Wolman channel-pattern threshold in the "braided channel" region, indicating that braiding, rather than a single-thread meandering channel, and midchannel bar formation may be the natural tendency of these gravel-bed reaches. When plotted against a total stream-power and median-sediment-size threshold for the 2 yr flood, however, the Lake Fork plotted in the "single-thread channel" region, the North Fork Gunnison plotted in the " multiplethread" region, and the Uncompahgre River plotted on the threshold. All three rivers plotted in the multiple-thread region for floods of 5 yr recurrence or greater. ?? 2009 Geological Society of America.

  2. Project river recovery: restoration of braided gravel-bed river habitat in New Zealand's high country.

    PubMed

    Caruso, Brian S

    2006-06-01

    Ecological restoration is increasingly becoming a primary component of broader environmental and water resources management programs throughout the world. The New Zealand Department of Conservation implemented Project River Recovery (PRR) in 1991 to restore unique braided gravel-bed river and wetland habitat in the Upper Waitaki Basin in New Zealand's high country of the South Island, which has been severely impacted by hydroelectric power development. These braided rivers are highly dynamic, diverse, and globally important ecosystems and provide critical habitat to numerous native wading and shore bird species, including several threatened species such as the black stilt. The objective of this study was to review and summarize PRR after more than 10 years of implementation to provide information and transfer knowledge to other nations and restoration programs. Site visits were conducted, discussions were held with key project staff, and project reports and related literature were reviewed. Primary components of the program include pest plant and animal control, wetland construction and enhancement, a significant research and monitoring component, and public awareness. The study found that PRR is an excellent example of an ecological restoration program focusing on conserving and restoring unique habitat for threatened native bird species, but that also includes several secondary objectives. Transfer of knowledge from PRR could benefit ecological restoration programs in other parts of the world, particularly riverine floodplain and braided river restoration. PRR could achieve even greater success with expanded goals, additional resources, and increased integration of science with management, especially broader consideration of hydrologic and geomorphologic effects and restoration opportunities. PMID:16508798

  3. Establishment of woody riparian species from natural seedfall at a former gravel pit

    USGS Publications Warehouse

    Roelle, J.E.; Gladwin, D.N.

    1999-01-01

    Establishment of native riparian communities through natural seedfall may be a viable reclamation alternative at some alluvial sand and gravel mines where water level can be controlled in the abandoned pit. We experimented with this approach at a pit in Fort Collins, Colorado, where a drain culvert equipped with a screw gate allows water levels to be manipulated. From 1994 to 1996 we conducted a series of annual drawdowns during the period of natural seedfall of Populus deltoides subsp. monilifera (plains cottonwood), Salix amygdaloides (peachleaf willow), and S. exigua (sand-bar willow), thus providing the bare, moist substrate conducive to establishment of these species. Establishment was highly variable from year to year; in the fall following establishment, frequency of occurrence on 0.5-m2 sample plots ranged from 8.6% to 50.6% for cottonwood, 15.9% to 22.0% for peachleaf willow, and 21.7% to 50.0% for sandbar willow. Mean densities, however, were comparable to those reported for other locations. Concurrent establishment of the undesirable exotic Tamarix ramosissima (saltcedar) was a problem, but we were able to eradicate most saltcedar seedlings by reflooding the lower elevations of the annual drawdown zones each fall. At the end of the 3-year period, at least one of the three native woody species survived on 41.1% of the plots, while saltcedar was present on only 6.1%. In addition to the potential for establishing valuable native habitats, adaptations of the techniques described may require less earth moving than other reclamation approaches.

  4. The influence of topology on hydraulic conductivity in a sand-and-gravel aquifer

    USGS Publications Warehouse

    Morin, R.H.; LeBlanc, D.R.; Troutman, B.M.

    2010-01-01

    A field experiment consisting of geophysical logging and tracer testing was conducted in a single well that penetrated a sand-and-gravel aquifer at the U.S. Geological Survey Toxic Substances Hydrology research site on Cape Cod, Massachusetts. Geophysical logs and flowmeter/pumping measurements were obtained to estimate vertical profiles of porosity ??, hydraulic conductivity K, temperature, and bulk electrical conductivity under background, freshwater conditions. Saline-tracer fluid was then injected into the well for 2 h and its radial migration into the surrounding deposits was monitored by recording an electromagnetic-induction log every 10 min. The field data are analyzed and interpreted primarily through the use of Archie's (1942) law to investigate the role of topological factors such as pore geometry and connectivity, and grain size and packing configuration in regulating fluid flow through these coarse-grained materials. The logs reveal no significant correlation between K and ??, and imply that groundwater models that link these two properties may not be useful at this site. Rather, it is the distribution and connectivity of the fluid phase as defined by formation factor F, cementation index m, and tortuosity ?? that primarily control the hydraulic conductivity. Results show that F correlates well with K, thereby indicating that induction logs provide qualitative information on the distribution of hydraulic conductivity. A comparison of ??, which incorporates porosity data, with K produces only a slightly better correlation and further emphasizes the weak influence of the bulk value of ?? on K. Copyright ?? 2009 The Author(s) are Federal Government Employees. Journal compilation ?? 2009 National Ground Water Association.

  5. Shifting Gravel and the Acoustic Detection Range of Killer Whale Calls

    NASA Astrophysics Data System (ADS)

    Bassett, C.; Thomson, J. M.; Polagye, B. L.; Wood, J.

    2012-12-01

    In environments suitable for tidal energy development, strong currents result in large bed stresses that mobilize sediments, producing sediment-generated noise. Sediment-generated noise caused by mobilization events can exceed noise levels attributed to other ambient noise sources at frequencies related to the diameters of the mobilized grains. At a site in Admiralty Inlet, Puget Sound, Washington, one year of ambient noise data (0.02 - 30 kHz) and current velocity data are combined. Peak currents at the site exceed 3.5 m/s. During slack currents, vessel traffic is the dominant noise source. When currents exceed 0.85 m/s noise level increases between 2 kHz and 30 kHz are correlated with near-bed currents and bed stress estimates. Acoustic spectrum levels during strong currents exceed quiescent slack tide conditions by 20 dB or more between 2 and 30 kHz. These frequencies are consistent with sound generated by the mobilization of gravel and pebbles. To investigate the implications of sediment-generated noise for post-installation passive acoustic monitoring of a planned tidal energy project, ambient noise conditions during slack currents and strong currents are combined with the characteristics of Southern Resident killer whale (Orcinus orca) vocalizations and sound propagation modeling. The reduction in detection range is estimated for common vocalizations under different ambient noise conditions. The importance of sediment-generated noise for passive acoustic monitoring at tidal energy sites for different marine mammal functional hearing groups and other sediment compositions are considered.

  6. Bedform morphology of salmon spawning areas in a large gravel-bed river

    SciTech Connect

    Hanrahan, Timothy P.

    2007-05-01

    While the importance of river channel morphology to salmon spawning habitat is increasingly recognized, quantitative measures of the relationships between channel morphology and habitat use are lacking. Such quantitative measures are necessary as management and regulatory agencies within the Pacific Northwestern region of the USA, and elsewhere, seek to quantify potential spawning habitat and develop recovery goals for declining salmon populations. The objective of this study was to determine if fall Chinook salmon (Oncorhynchus tshawytscha) spawning areas in the Snake River, Idaho, USA, were correlated with specific bed form types at the pool-riffle scale. A bed form differencing technique was used to objectively quantify the longitudinal riverbed profile into four distinct pool-riffle units that were independent of discharge. The vertical location of thalweg points within these units was quantified with a riffle proximity index. Chinook salmon spawning areas were mapped and correlated with the pool-riffle units through the use of cross-tabulation tables. The results indicate that 84% of fall Chinook salmon spawning areas were correlated with riffles (Chi-square=152.1, df=3, p<0.001), with 53% of those areas located on the upstream side of riffle crests. The majority of Snake River fall Chinook salmon spawning occurred at a vertical location within 80% of the nearest riffle crest elevation. The analyses of bed form morphology will assist regional fish mangers in quantifying existing and potential fall Chinook salmon spawning habitat, and will provide a quantitative framework for evaluating general ecological implications of channel morphology in large gravel-bed rivers.

  7. Analytical study on the suitability of using bentonite coated gravel as a landfill liner material

    SciTech Connect

    Roberts, Anel A. Shimaoka, Takayuki

    2008-12-15

    This study investigates the feasibility of using bentonite coated gravel (BCG) as a liner material for waste landfills. BCG has proven to be a very effective capping material/method for the remediation of contaminated sediments in aquatic environments. The concept of BCG is similar to that of peanuts/almonds covered with chocolate; each aggregate particle has been covered with the clayey material. Laboratory tests were aimed at evaluating regulated and non-regulated factors for liner materials, i.e., permeability and strength. Tests included X-ray diffraction, methylene blue absorption, compaction, free swelling, permeability, 1D consolidation, triaxial compression and cone penetration. The compactive efforts used for this study were the reduced Proctor, standard Proctor, intermediate Proctor, modified Proctor and super modified Proctor. The compactive energy corresponding to each effort, respectively, is as follows: 355.5, 592.3, 1196.3, 2693.3, and 5386.4 kJ/m{sup 3}. Results revealed that even though aggregate content represents 70% of the weight of the material, hydraulic conductivities as low as 6 x 10{sup -10} cm/s can be achieved when proper compactive efforts are used. Compressibility is very low for this material even at low (or no) compactive efforts. Results also demonstrated how higher compactive efforts can lower the permeability of BCG; however, over-compaction creates fractures in the aggregate core of BCG that could increase permeability. Moreover, higher compactive efforts create higher swelling pressures that could compromise the performance of a barrier constructed using BCG. As a result of this study, moderate compactive efforts, i.e., intermediate Proctor or modified Proctor, are recommended for constructing a BCG barrier. Using moderate compactive efforts, very low hydraulic conductivities, good workability and good trafficability are easily attainable.

  8. Denitrification in a Sand and Gravel Aquifer: An Overview of a Long-Term Study

    NASA Astrophysics Data System (ADS)

    Smith, R. L.

    2002-12-01

    Denitrification can be a key process affecting the concentration and transport of nitrate in the subsurface. As a dissimilatory process, it has the potential to consume significant amounts of nitrate, once oxygen has been depleted, while serving as the predominant terminal electron-accepting reaction for the microbial food chain. Although denitrification has been extensively studied in soils and some surface water systems, relatively little is known about the process in the saturated subsurface. Consequently, a long-term study was established to examine the occurrence of denitrification in a sewage-contaminated, sand and gravel aquifer on Cape Cod, Massachusetts. This study included a characterization of the effect of the process on spatial and temporal distribution of inorganic nitrogen species along aquifer flow paths, the effect on nitrogen stable isotope distributions, and the overall effect on the process of dispersion and consumption of dissolved oxygen and dissolved organic carbon. A variety of laboratory and field studies have been conducted to quantify the overall rate of denitrification relative to subsurface flow, factors that control the process in the Cape Cod aquifer, and the steady-state dynamics of electron flow through the individual steps of the denitrification pathway. Under some conditions, the pathway was found to be unbalanced in the aquifer, causing accumulation of nitrogen oxide intermediates (nitrite, nitrous oxide, and nitric oxide) in the groundwater. Another aspect of this study was utilization of denitrification as a tool to remediate subsurface nitrate contamination. This included in situ enhancement tests using formate as an added electron donor and a laboratory project testing specific groups of denitrifiers isolated from the aquifer. Overall this long-term study has demonstrated that small-scale heterogeneity is a major factor that dictates and controls denitrification in an aquifer at any given locale, even systems viewed as

  9. Soil erosion rates from mixed soil and gravel surfaces in a wind tunnel

    SciTech Connect

    Ligotke, M.W.; Klopfer, D.C.

    1990-08-01

    Protective barriers have been identified as integral components of plans to isolate defense waste on the Hanford Site. The use of natural materials to construct protective barriers over waste site is being considered. Design requirements for protective barriers include preventing exposure of buried waste, and restricting penetration or percolation of surface waters through the waste zone. Studies were initiated to evaluate the effects of wind erosion on candidate protective barrier surfaces. A wind tunnel was used to provide controlled erosive stresses and to investigate the erosive effects of wind forces on proposed surface layers for protective barriers. Mixed soil and gravel surfaces were prepared and tested for resistance to wind erosion at the Pacific Northwest Laboratory Aerosol Wind Tunnel Research Facility. These tests were performed to investigate surface deflation caused by suspension of soil from various surface layer configurations and to provide a comparison of the relative resistance of the different surfaces to wind erosion. Planning, testing, and analyzing phases of this wind erosion project were coordinated with other tasks supporting the development of protective barriers. These tasks include climate-change predictions, field studies and modeling efforts. This report provides results of measurements of deflation caused by wind forces over level surfaces. Section 2.0 reviews surface layer characteristics and previous relevant studies on wind erosion, describes effects of erosion, and discusses wind tunnel modeling. Materials and methods of the wind tunnel tests are discussed in Section 3.0. Results and discussion are presented in Section 4.0, and conclusions and recommendations Section 5.0. 53 refs., 29 figs., 7 tabs.

  10. Sewage plume in a sand and gravel aquifer, Cape Cod, Massachusetts

    USGS Publications Warehouse

    LeBlanc, D.R.

    1982-01-01

    Secondarily treated domestic sewage has been disposed of to a sand and gravel aquifer by infiltration through sand beds at Otis Air Force Base, Massachusetts, since 1936. The disposal has formed a plume of contaminated ground water that is more than 11 ,000 feet long, is 2,500 to 3,500 feet wide and 75 feet thick, and is overlain by 20 to 50 feet of uncontaminated ground water derived from precipitation. The distributions of specific conductance, temperature, boron chloride, sodium, phosphorus, nitrogen, ammonia, nitrate, dissolved oxygen, and detergents are used to delineate the plume. The center of the plume contains up to 2.6 milligrams per liter detergents as MBAS (methylene blue active substances), 0.4 milligram per liter boron, 20 milligrams per liter ammonia-nitrogen, and specific conductance as high as 405 micromhos per centimeter. Corresponding levels in uncontaminated ground water are less than 0.1 milligram per liter detergents, less than 0.1 ammonia-nitrogen, less than 0.05 milligram per liter boron, and less than 80 micromhos per centimeter specific conductance. Chloride, sodium, and boron concentrations seem to be affected only by hydrodynamic dispersion. Phosphorus movement is greatly retarded by sorption. Detergent concentrations exceed 0.5 milligram per liter from 3 ,000 to 10,000 feet from the sand beds and reflect the use of nonbiodegradable detergents from 1946 through 1964. The center of the plume as far as 5,000 feet from the sand beds contains nitrogen as ammonia, no nitrate, and no dissolved oxygen. Ammonia is oxidized to nitrate gradually with distance from the center of the plume. (USGS)

  11. Lidar characterization of crystalline silica generation and transport from a sand and gravel plant.

    PubMed

    Trzepla-Nabaglo, Krystyna; Shiraki, Ryoji; Holmén, Britt A

    2006-04-30

    Light detection and ranging (Lidar) remote sensing two-dimensional vertical and horizontal scans collected downwind of a sand and gravel plant were used to evaluate the generation and transport of geologic fugitive dust emitted by quarry operations. The lidar data give unsurpassed spatial resolution of the emitted dust, but lack quantitative particulate matter (PM) mass concentration data. Estimates of the airborne PM10 and crystalline silica concentrations were determined using linear relationships between point monitor PM10 and quartz content data with the lidar backscatter signal collected from the point monitor location. Lidar vertical profiles at different distances downwind from the plant were used to quantify the PM10 and quartz horizontal fluxes at 2-m vertical resolution as well as off-site emission factors. Emission factors on the order of 65-110 kg of PM10 (10-30 kg quartz) per daily truck activity or 2-4 kg/t product shipped (0.5-1 kg quartz/t) were quantified for this facility. The lidar results identify numerous elevated plumes at heights >30 m and maximum plume heights of 100 m that cannot be practically sampled by conventional point sampler arrays. The PM10 and quartz mass flux was greatest at 10-25 m height and decreased with distance from the main operation. Measures of facility activity were useful for explaining differences in mass flux and emission rates between days. The study results highlight the capabilities of lidar remote sensing for determining the spatial distribution of fugitive dust emitted by area sources with intermittent and spatially diverse dust generation rates. PMID:16442218

  12. Modeling wood dynamics, jam formation, and sediment storage in a gravel-bed stream

    NASA Astrophysics Data System (ADS)

    Eaton, B. C.; Hassan, M. A.; Davidson, S. L.

    2012-12-01

    In small and intermediate sized streams, the interaction between wood and bed material transport often determines the nature of the physical habitat, which in turn influences the health of the stream's ecosystem. We present a stochastic model that can be used to simulate the effects on physical habitat of forest fires, climate change, and other environmental disturbances that alter wood recruitment. The model predicts large wood (LW) loads in a stream as well as the volume of sediment stored by the wood; while it is parameterized to describe gravel bed streams similar to a well-studied field prototype, Fishtrap Creek, British Columbia, it can be calibrated to other systems as well. In the model, LW pieces are produced and modified over time as a result of random tree-fall, LW breakage, LW movement, and piece interaction to form LW jams. Each LW piece traps a portion of the annual bed material transport entering the reach and releases the stored sediment when the LW piece is entrained and moved. The equations governing sediment storage are based on a set of flume experiments also scaled to the field prototype. The model predicts wood loads ranging from 70 m3/ha to more than 300 m3/ha, with a mean value of 178 m3/ha: both the range and the mean value are consistent with field data from streams with similar riparian forest types and climate. The model also predicts an LW jam spacing that is consistent with field data. Furthermore, our modeling results demonstrate that the high spatial and temporal variability in sediment storage, sediment transport, and channel morphology associated with LW-dominated streams occurs only when LW pieces interact and form jams. Model runs that do not include jam formation are much less variable. These results suggest that river restoration efforts using engineered LW pieces that are fixed in place and not permitted to interact will be less successful at restoring the geomorphic processes responsible for producing diverse, productive

  13. Mapping water surface roughness in a shallow, gravel-bed river using hyperspectral imagery

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Rapid advances in remote sensing are narrowing the gap between the data available for characterizing physical and biological processes in rivers and the information needed to guide river management decisions. The availability and quality of hyperspectral imagery have increased drastically over the past 20 years and hyperspectral data is now used in a number of different capacities that range from classifying riverine environments to measuring river bathymetry. A fundamental challenge in relating the spectral data from images to biophysical processes is the difficulty of isolating individual contributions to the at-sensor radiance, each associated with a different component of the fluvial environment. In this presentation we describe a method for isolating the contribution of light reflected from the water surface, or sun glint, from a hyperspectral image of a shallow gravel-bed river. We show that isolation and removal of sun glint can improve the accuracy of spectrally-based depth retrieval in cases where sun glint dominates the at-sensor radiance. Observed-vs.-predicted R2 values for depth retrieval improved from 0.56 to 0.68 following sun glint removal. In addition to clarifying the signal associated with the water column and bed, isolating sun glint could unlock important hydraulic information contained within the topography of the water surface. We present data from flume and field experiments suggesting that the intensity of sun glint is a function of water surface roughness. In rivers, water surface roughness depends on local flow hydraulics: depth, velocity, and bed material grain size. To explore this relationship, we coupled maps of image-derived sun glint with hydraulic measurements collected with a kayak-borne acoustic Doppler current profiler along 2 km of the Snake River in Grand Teton National Park. Spatial patterns of sun glint are spatially correlated with field observations of near-surface velocity and depth, suggesting that reach scale hydraulics

  14. Double-averaged turbulent structure of gravel-bed river flows

    NASA Astrophysics Data System (ADS)

    Franca, M.; Ferreira, R. M. L.; Lemmin, U.

    2009-04-01

    River modelers need input on the flow turbulence structure from actual field measurements in order to resolve turbulence equation closures. The present work presents and discusses instantaneous velocity measurements made in the Swiss river Venoge using a 3D Acoustic Doppler Velocity Profiler. The measurements were made on a 3x5 rectangular horizontal grid (x-y). Fifteen velocity profiles were equally spaced in the spanwise direction with a distance of 10 cm, and in the streamwise direction with a distance of 15 cm. The vertical resolution of the measurements is roughly 0.5 cm. A measuring grid covering a 3D control volume was defined. The local topography of the riverbed was determined by the sonar-backscattered response. The instantaneous velocity profiles were measured for 3.5 min with a sampling frequency of 26 Hz. The riverbed is hydraulically rough, composed of coarse round gravel, with relative submergence of 2.94. The presence of large roughness in river flows induces major changes in the turbulence structure, especially within the inner layer. Turbulent intensities and turbulent kinetic energy values grow roughly according with the expected for smooth flows from the surface until roughly z/h?0.40; maximum turbulent kinetic energy values are typically observed at the upper limit of the roughness layer. Below this level their distribution is determined by local effects of the randomly distributed bed-forms where large spatial variations are observed. The large spatial deviations in the turbulence structure of the flow may only be adequately account for by applying double-averaging (both in space and time) methods - DAM. This methodology constitutes an adequate theoretical supported framework to account for the spatial and time variability of low submergence flows. From the application of a spatial averaging operator to the Reynolds Averaged Navier-Stokes equations, the terms related the influence of the bed form become evident: changes in the velocity

  15. Modeling of replenishment of sediments on a water-worked gravel bed channel

    NASA Astrophysics Data System (ADS)

    Juez, Carmelo; Battisacco, Elena; Schleiss, Anton J.; Franca, Mário J.

    2016-04-01

    the area percentage that is covered by the replenishment material, (iii) travel distance of the center of the pulse mass and (iv) effect of the bed fining in the bed shear stress. The results of these experiments assist in further evaluating how water-worked gravel bed channels evolve with artificial replenishment of sediments. This work was funded by the ITN-Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme FP7-PEOPLE-2013-ITN under REA grant agreement n_607394-SEDITRANS. The sediment replenishment experiments were funded by FOEN (Federal Office for the Environment, Switzerland).

  16. Bed surface bed profile adjustments to a series of water pulses in gravel bed rivers

    NASA Astrophysics Data System (ADS)

    Ferrer-Boix, C.; Hassan, M. A.

    2014-12-01

    This research aims to explore the interactions between the bed surface texture, the bed topography and the sediment transport (rate and grain size distribution) to a series of water pulses in gravel bed-rivers. We conducted a set of runs in a 18 m-long tilting flume, 1 m-wide. Low flow discharges (Q = 65 l/s) during periods of variable duration (between t = 10 h and t = 1 h) were alternated with high flow rates (Q = 90 l/s) of constant duration (t = 1.5 h). Sediment was fed at a constant rate (Qfeed = 7.5 kg/h) throughout the runs. Eight experiments were consecutively conducted: the final configuration of the previous run was the initial condition for the subsequent experiment. The initial bed texture of the experiments was obtained after a 280 h-long run at low flow, the last 40 h of which under starving conditions. The initial bed slope was S0 = 0.022 m/m. A poorly-sorted grain size distribution (Dg = 5.65 mm and sg = 3.05) was used as a feeding material. The same material was used as the initial condition for the antecedent experiment (280 h-long). Intensive measurements of the bed surface, bed topography and sediment transport were taken during the runs. Provisional results of the experimental campaign demonstrate that: (i) bed topography rapidly adjusts to water pulses: bed aggrades during low flow periods to subsequently degrade during water pulses. However, the rate of change of the bed profile decreases with the number of water pulses; (ii) the surface texture maintains an approximately invariant texture during the runs with no significant changes before and after the pulses; (iii) bedload transport dramatically adjusts to water pulses (increasing its rate and getting coarser). The relative increase in the bedload transport during the pulses diminishes as the number of pulses increases. A detailed analysis of the evolution of the bed profile shows the formation of transverse ribs during low flow periods which slowly migrate upstream. These bedforms are not

  17. Channel dynamics and habitat complexity in a meandering, gravel-bed river

    NASA Astrophysics Data System (ADS)

    Harrison, L. R.; Legleiter, C. J.; Pecquerie, L.; Dunne, T.

    2009-12-01

    River channel dynamics play an important role in creating and maintaining diverse habitat conditions for multiple life stages of aquatic organisms. As a result, many river restoration projects seek to re-establish ecosystems in which an enhanced degree of habitat complexity is sustained through natural fluvial processes of flow, sediment transport, and channel change. Few field cases have effectively quantified the evolution of channel morphology and habitat complexity in restored rivers, however, and the outcomes of restoration actions remain difficult to predict. Our objective was to quantify the extent to which morphology, flow complexity and salmonid spawning and rearing habitat develop from the simplified initial conditions commonly observed in re-configured meandering channels. Using a time-series of topographic data, we measured rates of morphologic change in a recently restored gravel-bed reach of the Merced River, California, USA. We constructed two-dimensional (2D) hydrodynamic models to quantify how the evolving morphology influenced hydraulic conditions, flow complexity and suitability for Chinook salmon spawning and rearing. Following two large flood events, point bar development led to order-of-magnitude increases in modeled flow complexity, as quantified via the metrics of kinetic energy gradient, vorticity and hydraulic strain. On a bend-averaged scale, morphologic changes produced up to a two-fold increase in flow circulation, indicating a direct linkage between geomorphic processes and the development of habitat complexity at both the local (1.0 m2 grid cell) and meander wavelength scale. Habitat modeling indicated that the availability of Chinook salmon spawning habitat has increased over time, whereas the majority of the reach provides low-medium quality rearing habitat for juvenile salmonids, primarily due to a lack of low velocity refuge zones. These results demonstrate the ability of geomorphic processes to increase flow complexity and

  18. Total Dissolved Gas Monitoring in Chum Salmon Spawning Gravels Below Bonneville Dam

    SciTech Connect

    Arntzen, Evan V.; Geist, David R.; Panther, Jennifer L.; Dawley, Earl

    2007-01-30

    At the request of the U.S. Army Corps of Engineers (Portland District), Pacific Northwest National Laboratory (PNNL) conducted research to determine whether total dissolved gas concentrations are elevated in chum salmon redds during spring spill operations at Bonneville Dam. The study involved monitoring the total dissolved gas levels at egg pocket depth and in the river at two chum salmon spawning locations downstream from Bonneville Dam. Dissolved atmospheric gas supersaturation generated by spill from Bonneville Dam may diminish survival of chum (Oncorhynchus keta) salmon when sac fry are still present in the gravel downstream from Bonneville Dam. However, no previous work has been conducted to determine whether total dissolved gas (TDG) levels are elevated during spring spill operations within incubation habitats. The guidance used by hydropower system managers to provide protection for pre-emergent chum salmon fry has been to limit TDG to 105% after allowing for depth compensation. A previous literature review completed in early 2006 shows that TDG levels as low as 103% have been documented to cause mortality in sac fry. Our study measured TDG in the incubation environment to evaluate whether these levels were exceeded during spring spill operations. Total dissolved gas levels were measured within chum salmon spawning areas near Ives Island and Multnomah Falls on the Columbia River. Water quality sensors screened at egg pocket depth and to the river were installed at both sites. At each location, we also measured dissolved oxygen, temperature, specific conductance, and water depth to assist with the interpretation of TDG results. Total dissolved gas was depth-compensated to determine when levels were high enough to potentially affect sac fry. This report provides detailed descriptions of the two study sites downstream of Bonneville Dam, as well as the equipment and procedures employed to monitor the TDG levels at the study sites. Results of the monitoring at

  19. Monitoring Sediment Size Distributions in a Regulated Gravel-Bed Coastal Stream

    NASA Astrophysics Data System (ADS)

    O'Connor, M. D.; Lewis, J.; Andrew, G.

    2014-12-01

    Lagunitas Creek drains 282 km2 in coastal Marin County, California. The watershed contains water supply reservoirs, urban areas, parks and habitat for threatened species (e.g. coho salmon). Water quality is impaired by excess fine sediment, and a plan to improve water quality (i.e. TMDL) was adopted by State authorities in 2014. The TMDL asserts changes in sediment delivery, transport, and storage contributed to the decline of coho. A sediment source analysis found a 2x increase in sediment supply. Concentrations of sand and fine gravel in the channel are elevated and, during high flows, more mobile. The Federal Coho Salmon Recovery Plan (2012) describes sediment conditions affecting coho habitat as "fair". Reservoir managers were directed by the State in 1995 to reduce sedimentation and improve riparian vegetation and woody debris to improve fish habitat. Prior sediment monitoring found variability related primarily to intense winter runoff without identifying clear trends. A new sediment monitoring program was implemented in 2012 for ongoing quantification of sediment conditions. The goal of monitoring is to determine with specified statistical certainty changes in sediment conditions over time and variation among reaches throughout the watershed. Conditions were compared in 3 reaches of Lagunitas Cr. and 2 tributaries. In each of the 5 channel reaches, 4 shorter reaches were sampled in a systematic grid comprised of 30 cross-channel transects spaced at intervals of 1/2 bankfull width and 10 sample points per transect; n=1200 in 5 channel reaches. Sediment diameter class (one clast), sediment facies (a patch descriptor), and habitat type were observed at each point. Fine sediment depth was measured by probing the thickness of the deposit, providing a means to estimate total volume of fine sediment and a measure of rearing habitat occupied by fine sediment (e.g. V*). Sub-surface sediment samples were collected and analyzed for size distribution at two scales: a

  20. Landforms Affect Gravel-Cobble Bed River Hydraulics at Different Spatial Scales and Discharges

    NASA Astrophysics Data System (ADS)

    Gonzalez, R. L.; Pasternack, G. B.; Wyrick, J. R.; Johnson, T.

    2012-12-01

    River hydraulics are generally modeled to predict inundation extents, assess aquatic species habitat, understand sediment transport regimes, and describe geomorphic processes. These metrics are in turn used to guide floodplain development, instream flow requirements, river rehabilitation projects, reservoir management, and further research. Consequently, the emergence of 2D hydraulic modeling is usually a means to some end other than characterizing and discussing the fundamental aspects of fluvial hydraulics. The purpose of this study was to ascertain the role of different components of multi-scalar, heterogeneous fluvial landforms in controlling the spatial pattern of river hydraulics at 28 different flows ranging from 0.06 to 22 times bankfull discharge. The testbed data for the study consisted of 1-m resolution rasters of depth, velocity, and Shields stress over 37.5 km of the regulated gravel-cobble bed Lower Yuba River (LYR) located in the Sacramento River Valley of California. Each variable was analyzed for its discharge-dependent power function (i.e. at-a-station hydraulic geometry) at segment, reach, and morphologic spatial scales, with data stratified by 8 reaches, 4 inundation zones, two vegetation regions, and 31 morphological units. This was done using all points, not just at cross-sections. At each spatial scale, trend lines were statistically compared to determine if they were differentiated. Mean velocity and Shields stress as a function of discharge vary by reach, including several velocity and Shields stress reversals. The range of mean velocity and Shields stress between reaches increases with discharge. There are several reach-scale velocity reversals that take place among the reaches, especially at 0.3 and 2 times bankfull discharge, whereas there is only one major Shields stress reversal at 6 times bankfull discharge. Stage-dependent cross sectional area and substrate size govern these interactions. The two most downstream reaches had the

  1. Lithologic Influence and Experimental Variability in Gravel Abrasion: Implications for Predicting Rates of Downstream Fining of River Bed Sediments

    NASA Astrophysics Data System (ADS)

    Farrow, J. W.; Sklar, L. S.

    2004-12-01

    The question of what controls the occurrence and rate of downstream fining of bed-material sediments remains a fundamental unsolved problem despite over a century of field, experimental and theoretical investigations. Downstream fining rates are commonly modeled as exponential or power-law functions of travel distance. Much recent work has focused on the relative influence of particle abrasion and differential transport, however, no general method has been developed for explicitly accounting for the influence of rock strength in parameterizing fining models. Here we report preliminary results of laboratory tumbling experiments in which we are investigating the influence of variable rock durability, both between and within distinct lithologic units, on rates of particle abrasion. We consider three separate questions: 1) can rock tensile strength be used to predict differences in bulk fining rates across a wide spectrum of rock types; 2) does variability in rock durability among individual gravel clasts of the same lithologic composition and initial grain size lead to patterns of downstream evolution of grain size distributions that differ significantly from the predictions of simple fining models; and 3) how large is the uncertainty in abrasion coefficients determined by laboratory tumbling, as determined by replicate experiments with identical initial conditions? We use a horizontal axis, 25-cm diameter, steel barrel tumbler, driven by a mechanical transmission with excellent control of rotational velocity. Rock samples were collected from units of the Franciscan Formation in the Redwood Creek Watershed of Marin County, California, and from sedimentary and intrusive volcanic rocks of the Henry Mountains, in southeastern Utah. We collected clasts predominantly from hillslope source areas, to focus our attention on the durability of gravel as it enters the river network. We use the `Brazilian' tensile splitting test to measure the strength of 50-mm diameter core

  2. Effect of HRT on nitrogen removal in a coupled HRP and unplanted subsurface flow gravel bed constructed wetland

    NASA Astrophysics Data System (ADS)

    Mayo, A. W.; Mutamba, J.

    This paper discusses the effect of hydraulic retention time (HRT) on nitrogen removal in a coupled high rate pond (HRP) and a gravel bed subsurface constructed wetland (SSCW) wastewater treatment plant. A pilot plant consisting of a high rate pond (HRT) coupled to an unplanted gravel bed subsurface constructed wetland (SSCW) was used to investigate nitrogen removal from domestic wastewater at the University of Dar es Salaam. The influent, which is predominantly of domestic origin, was drawn from the facultative pond unit of the university’s waste stabilisation pond system. The pilot plant’s HRP unit, which was 0.6 m deep, was designed to nitrify the influent while SSCW unit, which was filled to 10 cm above water level with 19-mm diameter aggregates, was predominantly anoxic and promoted denitrification. The study was conducted at two different operational settings. In Phase 1, both the HRP and the SSCW units had a retention time of 5 days. During Phase 2, the hydraulic retention time in HRP was increased to 8 days while the retention time of the SSCW unit was maintained at 5 days. Samples were collected daily for laboratory analysis of influent and effluent wastewater quality. All experiments were conducted in accordance with Standard Methods. The results showed that improved nitrogen removal occurred with increase in hydraulic time of the HRP unit. In Phase 1 an average nitrogen removal of 33% was achieved while removal efficiency improved to 43% in Phase 2. It was also revealed that the HRP can effectively be used to promote nitrification and the unplanted gravel bed subsurface constructed wetland can be used as a denitrifying unit.

  3. Effects of near-bed turbulence and micro-topography on macroinvertebrate movements across contrasting gravel-bed surfaces (Invited)

    NASA Astrophysics Data System (ADS)

    Buffin-Belanger, T. K.; Rice, S. P.; Reid, I.; Lancaster, J.

    2009-12-01

    Fluvial habitats can be described from a series of physical variables but to adequately address the habitat quality it becomes necessary to develop an understanding that combines the physical variables with the behaviour of the inhabitating organisms. The hypothesis of flow refugia provide a rational that can explain the persistence of macroinvertebrate communities in gravel-bed rivers when spates occur. The movement behaviour of macroinvertebrates is a key element to the flow refugia hypothesis, but little is known about how local near-bed turbulence and bed microtopography may affect macroinvertebrate movements. We reproduced natural gravel-bed substrates with contrasting gravel bed textures in a large flume where we were able to document the movement behaviour of the cased caddisfly Potamophylax latipennis for a specific discharge. The crawling paths and drift events of animals were analysed from video recordings. Characteristics of movements differ from one substrate to another. The crawling speed is higher for the small grain-size substrates but the mean travel distance remains approximately the same between substrates. For each substrate, the animals tended to follow consistent paths across the surface. The number of drift events and mean distance drifted is higher for the small grain-size substrate. ADV measurements close to the boundary allow detailed characterisation of near-bed hydraulic variables, including : skewness coefficients, TKE, UV correlation coefficients and integral time scales from autocorrelation analysis. For these variables, the vertical patterns of turbulence parameters are similar between the substrates but the amplitude of the average values and standard errors vary significantly. The spatial distribution of this variability is considered in relation to the crawling paths. It appears that the animals tend to crawl within areas of the substrate where low flow velocities and low turbulent kinetic energies are found, while sites that

  4. What gravel size may tell us about the rivers draining from the north wall of Gale Crater

    NASA Astrophysics Data System (ADS)

    Dietrich, W. E.; Palucis, M. C.; Williams, R. M. E.; Lewis, K. W.; Rivera-Hernandez, F.; Sumner, D. Y.

    2015-12-01

    The exposures of interbeds of mostly fine gravels observed en route to Pahrump Valley in Gale Crate appear to provide no direct indication of channel scale or slope, but they for the first time on Mars reveal the bedload grain size distribution. This is in contrast to remote sensing analysis of Martian channel landforms where width and slope can be estimated and possibly flow depth inferred, but grain size of the channel bed is unknown. Strong terrestrial correlations of discharge and channel width (once corrected for reduced velocity due to lower gravity) likely gives the best estimates of channel flows from remote sensing observations. Calculations based on roughness arguments or estimated grain size and critical shear stresses have much larger error. What can be done, however, if we only know the grain size- the case for the gravel exposures in Gale? We show that crude positive correlations of channel slope with median grain size, can then be used to estimate channel depth and width, each of which vary inversely with channel slope. These empiricisms suggest that the fluvial conglomerates in Gale with grain sizes 4.5 to 9.5 mm may have had been deposited by a channel of a slope between 0.01 and 0.0001, about 0.62 to 2.1 m deep, and 10 to 50 m wide. Using the median bankfull stream velocity from terrestrial studies of 0.9 m/s (corrected for Martian gravity) the predicted discharge is about 5.6 to 94.5 m3/s. The estimated widths alone predict 6 to 85.6 m3/s for the 10 to 50 m channels widths, respectively. This analysis suggests that the gravel bedded rivers that delivered the sand and finer size delta building sediment towards the base of the present Mt. Sharp were of modest scale and slope, placing constraints on the eventual stratigraphic reconstruction of the deposits here.

  5. What Happens During a Minor Flood: Observations of Bedload Transport in a Gravel Bed River using New Methods

    NASA Astrophysics Data System (ADS)

    Bray, E. N.; Dunne, T.

    2015-12-01

    The question of "does the streambed change over a flood" does not have a clear answer due to lack of measurement methods during high flows. We seek to inform our understanding of bedload transport by linking field measurements using fiber optic distributed temperature sensing (DTS) cable, calculations of disentrainment over time and distance, and in situ measurements of streambed permeability with sediment transport theory and an existing explicit analytical solution to predict depth of sediment deposition and one-dimensional fluid velocity from amplitude and phase information. The method facilitates the study of gravel transport by using near-bed temperature time series to estimate rates of sediment deposition continuously over the duration of a minor flood coinciding with bar formation, including (1) a field method for measuring local rates of deposition and bed elevation change during a minor flood to compute rates of bedload transport, (2) use of an existing analytical solution to quantify the depth of sediment deposition over distance and time from temperature amplitude and phase information, (3) observational and theoretical evidence that incipient motion occurs during a minor flood, (4) observational evidence that suggests rates of sediment transport are not necessarily constant during a constant flow, and (5) field evidence for the persistence of armor layers in gravel bed rivers during a minor flood. These observations of partial bedload transport, taken along a 2 km gravel bed reach of the San Joaquin River, CA, USA during an experimental flow release, suggest that the discharge needed to create the boundary shear is lower than previous estimates, and that partial transport of grain sizes on the bed, including the median particle size, occurs during a minor flood with a current recurrence interval of approximately 1-2 years.

  6. Development of an integrated sediment transport model and application at a large gravel bed river

    NASA Astrophysics Data System (ADS)

    Tritthart, M.; Schober, B.; Liedermann, M.; Habersack, H.

    2009-04-01

    This paper presents the development, validation and application of iSed, an integrated numerical sediment transport and morphology model. The model was specifically designed to suit the needs of large gravel bed rivers, such as the Danube East of Vienna. It is coupled with external 2-D or 3-D hydrodynamic codes to obtain the flow field and bed shear stress patterns driving sediment transport processes. This approach is of particular advantage for an investigation into sediment dynamics based on hydrodynamics of different dimensionality. The model is capable of calculating both suspended and bed load transport. It solves a convection-diffusion equation to account for suspended load; in addition, four different transport formulae - the relations of Meyer-Peter/Müller, Hunziker, van Rijn and Egiazaroff - are implemented for the computation of bed load. The well-known Exner equation is solved for deriving resulting bed level differences for every node of the computation mesh based on the sediment balance. All equations are evaluated for an unlimited number of sediment size fractions, allowing for the investigation of sorting processes. The river bed is organized into an active layer, where sorting takes place, and an unlimited number of bed layers below the active layer. The sediment transport model was validated using results from three different laboratory experiments: (i) morphodynamics of a 180 degree channel bend, based on hydraulics of a 3-D numerical model; (ii) erosion and deposition patterns due to a channel contraction, using a 2-D model to provide the flow field; (iii) incipient motion and erosion processes due to different sediment materials in a straight laboratory channel, coupled with a 3-D numerical model. The results of the numerical code were in satisfactory agreement with the experimental measurements, demonstrating the general validity of the sediment transport model. After successful validation, the model was applied to a 4 kilometre reach of the

  7. Runoff and drainage water quality from geotextile and gravel pads used in livestock feeding and loafing areas.

    PubMed

    Singh, Anshu; Bicudo, José R; Workman, Stephen R

    2008-05-01

    Geotextile and gravel pads offer a low-cost alternative to concrete for providing all-weather surfaces for cattle and vehicle traffic, and are used in many livestock facilities to minimize mud, runoff and erosion of heavy traffic areas. The objective of this study was to compare different combinations of geotextile and gravel used in heavy livestock traffic areas that minimize the potential for water pollution. Three different pad combinations were constructed in 2.4 x 6-m plots as follows: (i) woven geotextile+100mm of gravel+50mm Dense Grade Aggregate (DGA); (ii) woven geotextile + geoweb+100 mm DGA; and (iii) non-woven geotextile+152 mm of gravel+50mm DGA; (iv) mud lots as control. The third combination was equivalent to one of the base treatments specified by the Kentucky Natural Resource and Conservation Service (NRCS). All treatment combinations were duplicated. Lysimeter pans were installed in four out of eight plots for the collection of leachate or drainage water. Runoff was collected at the lower end of the plots. About 14 kg of beef cattle manure were added evenly to the plots. Rainfall at 50mm/h was applied using rainfall simulators. In the first five of ten experiments, manure was removed from the surface of the pads after each experiment. In the remaining five experiments manure accumulated on the surface of the pads. The effect of pad treatment was significant on the electrical conductivity (EC), total solids (TS), chemical oxygen demand (COD), nitrite (NO2-N), total nitrogen (TN) and total phosphorus (TP) values in surface runoff at the 5% level. Manure removal did not have any significant effect on the nutrient content of runoff or leachate samples except for ammonia (NH4-N) values. Although a mass balance indicated relatively small amounts of organic matter and nutrients were lost by runoff and leaching, the actual contamination level of both runoff and leachate samples were high; TP levels as high as 12 mg/l (5.4 mg/m2) in runoff and nitrate (NO3

  8. Monitoring of dust emission on gravel roads: Development of a mobile methodology and examination of horizontal diffusion

    NASA Astrophysics Data System (ADS)

    Edvardsson, Karin; Magnusson, Rolf

    Traffic-generated fugitive dust on gravel roads impairs visibility and deposits on the adjacent environment. Particulate matter smaller than 10 μm in diameter (PM 10) is also associated with human health problems. Dust emission strength depends on the composition of granular material, road moisture, relative humidity, local climate (precipitation, wind velocity, etc.), and vehicle characteristics. The objectives of this study were to develop a reliable and rapid mobile methodology to measure dust concentrations on gravel roads, evaluate the precision and repeatability of the methodology and correspondence with the currently used visual assessment technique. Downwind horizontal diffusion was studied to evaluate the risk of exceeding the maximum allowed particulate matter concentration in ambient air near gravel roads according to European Council Directive [European Council Directive 1999/30/EC of 22 April 1999 relating to limit values for sulphur dioxide, nitrogen dioxide and oxides of nitrogen, particulate matter and lead in ambient air. Official Journal of the European Communities. L163/41.]. A TSI DustTrak Aerosol Monitor was mounted on an estate car travelling along test sections treated with various dust suppressants. Measured PM 10 concentrations were compared to visual assessments performed at the same time. Airborne particles were collected in filters mounted behind the vehicle to compare the whole dust fraction with the PM 10 concentration. For measuring the horizontal diffusion, DustTraks were placed at various distances downwind of a dusty road section. The mobile methodology was vehicle and speed dependent but not driver dependent with pre-specified driving behaviours. A high linear correlation between PM 10 of different vehicles makes relative measurements of dust concentrations possible. The methodology gives continuous data series, mobility, and easy handling and provides fast, reliable and inexpensive measurements for estimating road conditions to

  9. Gravel-bed deposition and erosion by bedform migration observed ultrasonically during storm flow, North Fork Toutle River, Washington

    USGS Publications Warehouse

    Dinehart, R.L.

    1992-01-01

    Bed elevation records from the dual depth sounders were used to calculate dune celerities of 3–6 cm s−1 and bedform wavelengths of 2–11 m. The large bed waves were subtle, dune-like gravel bedforms with wavelengths of 25–30 m. The celerities and bedform dimensions yielded bedform transport weight rates between 3 and 20 kg s−1 m−1 and grain shear stresses between 40 and 100 N m−2 for the depth-sounding episode.

  10. Influences on Bed Sorting and Armoring in an Upland Gravel-Cobble Bed River, Middle Fork John Day River, Oregon

    NASA Astrophysics Data System (ADS)

    McDowell, P. F.

    2014-12-01

    The Middle Fork is an unconfined to partly confined upland river with channel length of 34 km, drainage area of 250-850 km2, and channel gradients of 0.004 to 0.006 in the study area. Geology is dominated by Tertiary volcanic and volcaniclastic rocks that yield abundant coarse clasts. Surface and subsurface bed material was sampled volumetrically at twenty-five sites. The textural types range from gravelly cobbles to sandy cobbly gravels, sand content is low (2 to 13%), mud content is very low, and sorting is poor to very poor. Generally the surface layer is an open framework gravel or cobble, while the subsurface layer is a filled or partially filled framework gravel or cobble. Despite an armored appearance, only 20% of the sites are armored using the standard armor ratio (surface D50/subsurface D50). While surface layers are not coarser than their subsurface layers in terms of the median or coarse end of the distribution, they are coarser in terms of fines (ratios based on D25, D16, % sand), suggesting that alternatives to the D50armor ratio might be useful. Multivariate analysis of size fraction data reveals four distinct groups of samples, distinguished mainly by differences in proportions of coarse to fine gravels, and in abundance of sand. While one group comprises only surface samples and another subsurface samples, two of the groups are mixed. One goal of the project is to evaluate the effects of land use history on bed material characteristics and mobility. Sediment characteristics were examined in relation to distance downstream, geology, relation to debris-flow sources, land use history, and other potential influences. There are no geologic associations or downstream trends in fining or other grain size parameters. Differences in land use history, such as former dredged-mined reaches and reaches with recent restoration projects also do not explain patterns of armoring or other sediment characteristics. High variability within each reach suggests that

  11. Application of surface-geophysical methods to investigations of sand and gravel aquifers in the glaciated Northeastern United States

    USGS Publications Warehouse

    Haeni, F.P.

    1995-01-01

    Combined use of seismic-refraction, direct-current resistivity, very-low-frequency terrain-resistivity, and inductive terrain-conductivity methods were demonstrated at sites in Connecticut, New York, and Maine. Although no single method can define both the hydrogeologic boundaries and general grain-size characteristics of sand and gravel aquifers, a combination of these methods can. Comparisons of measured electrical properties of aquifers with logs of test holes and wells indicate that, for a given conductivity of ground water, the bulk electrical resistivity of aquifers in the glaciated Northeast increases with grain size.

  12. Quantifying Upper Particle-size Limits of Salmonid Spawning Gravel: Analysis of Fall-run Chinook Salmon of the Sacramento River

    NASA Astrophysics Data System (ADS)

    Wooster, J. K.; Riebe, C. S.; Ligon, F. K.

    2008-12-01

    Reversing the decline of historically prolific runs of Chinook salmon (Oncorhynchus tshawytscha) remains a high priority of river restoration along the US Pacific Coast. One routinely implemented strategy is gravel injection, to supplement spawning habitat which has been depleted by gravel mining and bed coarsening below dams. Gravel augmentation is generally designed around a qualitatively assessed "preferred" median particle size. Implementation sites are not always ecologically ideal, because there often is little quantitative basis for determining where added gravel would be most suitable. Although gravel augmentation may increase spawning habitat, a more mechanistic design basis could reduce costs, improve efficiency, and make results more predictable. One key to developing better designs is a better method for characterizing existing spawning gravel deposits. Here we propose a series of mechanistically oriented hypotheses about the spawning suitability of natural gravels. One hypothesis is that there is an upper size limit on particles that can be moved by salmon. We expect that this limit depends on salmon size, water velocity and the size (and embeddedness) of surrounding rocks. Another hypothesis is that spawning success is related to percent coverage by immovable particles. A corollary hypothesis is that redds become irregular (and less productive) as percent coverage by immovable particles increases. Another related hypothesis is that redd-building success should approach zero at an upper threshold of coverage by immovable particles. We explored our hypotheses for fall-run Chinook in the Sacramento River. We collected grain size data, constructed facies maps of the bed, and delineated boundaries of spawning use at the peak of spawning, prior to the run's recent population decline. Our observations suggest that particles with intermediate axes diameters bigger than about 130 mm are not generally movable by fall run Chinook. Moreover we observed no

  13. Influence of bank materials, bed sediment, and riparian vegetation on channel form along a gravel-to-sand transition reach of the Upper Tualatin River, Oregon, USA

    NASA Astrophysics Data System (ADS)

    Labbe, Jim M.; Hadley, Keith S.; Schipper, Aafke M.; Leuven, Rob S. E. W.; Gardiner, Christine Perala

    2011-02-01

    We examined the role of bed sediment size, bank materials, riparian vegetation, and discharge on channel form along a 10-km reach of the Upper Tualatin River, encompassing both gravel and sand-bed reaches. Statistical correlations and analyses of downstream changes of channel morphology reveal that bank materials and bed sediment are the dominant controls on channel cross section form. A rapid downstream reduction in bed sediment size in the gravel-bed channel is followed by an abrupt transition to a narrower, deeper, and less sinuous sand-bed channel with more cohesive bank materials. The simultaneous reductions in channel slope, bed sediment size, and width-to-depth ratio indicate the channel crosses a geomorphic threshold to maintain continuity in sediment transport. This gravel-to-sand transition and associated change in channel form are induced by a break in valley slope and an increase in bank resistance from cohesive bank materials. Bank materials, measured as the average percent silt and clay in banks, are a primary influence on channel form within both subreaches but demonstrate a greater influence on channel width and vertical stability in the gravel-bed channel and on channel depth and lateral stability in the sand-bed channel. Riparian vegetation at current densities and compositions is not a significant control on contemporary channel cross section form and may be responding to the bank and channel stability provided by cohesive bank materials in the laterally dynamic gravel-bed channel.

  14. Liftable Bedload Trap for Large Alpine Gravel-Bed Rivers - Experiences and Goals

    NASA Astrophysics Data System (ADS)

    Seitz, Hugo; Strahlhofer, Lukas; Habersack, Helmut

    2010-05-01

    The aim of the work is to figure out the bedload transport processes for the free flowing reach of the Drau River in Dellach, Drau Valley, amongst other measurement techniques also under the use of a recently invented liftable bedload trap. In general, there are some techniques for measuring transported debris in natural streams; we use collecting moving particles (Birkbeck-type traps, Large Helley Smith sampler) and indirectly determining transport intensity (geophones) at the study sites in Austria. In addition hydrological, geological, meteorological and other related data are collected. Two further almost fully equipped measurement stations in Lienz at the Drau River and its most important tributary Isel River, both large Alpine gravel-bed rivers, situated in the south western part of Austria are completing the integrative and innovative bedload measurement system. Former measurements in the study reach were performed also using mobile bedload samplers and fixed bedload samplers. Individually they all are adequate bedload measurement instruments - used in combination they are complementing one another, whereas each applied separately leads to specific deficits. In general the investigation pays special attention on results out of the geophone installations. The spatio-temporal distribution of the transported bedload material, its amount and the transport processes itself could be figured out. But for calibration purposes direct moving particle sampling is essential. Compared to Large Helley-Smith sampling fixed bedload traps are flood protected and robust to withstand the strain during flood conditions and so are capable to take bedload samples of e.g. a flood peak. The disadvantage of this type of direct bedload measurement is that in perennial alpine rivers the only chance to empty them and analyze their content is during the wintertime at very low water stages. Therefore a liftable bedload trap was installed direct downstream the geophone installation into

  15. Interaction of Bar Morphology and Riparian Vegetation in Gravel-Bed Rivers

    NASA Astrophysics Data System (ADS)

    Francalanci, S.; Bertoldi, W.; Siviglia, A.; Solari, L.; Toffolon, M.; Vetsch, D.

    2013-12-01

    Gravel-bed rivers are often characterized by complex bed topography, including single- and multiple-row alternate bars, bed undulations associated with channel curvature, riffle and pool sequences, presence of riparian vegetation in the floodplain, etc. The interaction of these features results in different morphologies with complex patterns and dynamics. The present work investigates the effect of the riparian vegetation on the bar dynamics, in particular it is investigated how the vegetation, which grows during the dry season on the bars, can alter the topographic patterns evolution during flood conditions. Performing two-dimensional numerical simulations we try to answer to the following research questions: which is the interaction of vegetation with bar morphology? which are the changes in sediment discharge and flow resistance, at cross-sectional and reach scale? Which are the changes in distribution of emerged and submerged areas, and potential feedbacks for vegetation growth? Which is the effect of vegetation on bar wave-length? The code BASEMENT (Faeh et al., 2010) has been used for performing the numerical runs. It has been properly modified in order to deal with the numerical description of the vegetation. The vegetation was allowed to grow during the dry season on the top of dry emergent areas, and the vertical distribution of vegetation in equilibrium condition was modeled as a function of the bed elevation using a simple analytical formulation, following Marani et al (2013). Then, during the flood events we assume that the vegetation distribution does not change, and that it can only be uprooted if the bed is eroded.The flow resistance was divided into a resistance exerted by the soil and a resistance exerted by the plants (Crosato and Saleh, 2010; Li and Millar, 2011); in this way it was possible to reproduce both the decrease in bed shear stress, reducing the sediment transport capacity of the flow within the plants, and the increase in hydraulic

  16. Assessment Approach for Identifying Compatibility of Restoration Projects with Geomorphic and Flooding Processes in Gravel Bed Rivers.

    PubMed

    DeVries, Paul; Aldrich, Robert

    2015-08-01

    A critical requirement for a successful river restoration project in a dynamic gravel bed river is that it be compatible with natural hydraulic and sediment transport processes operating at the reach scale. The potential for failure is greater at locations where the influence of natural processes is inconsistent with intended project function and performance. We present an approach using practical GIS, hydrologic, hydraulic, and sediment transport analyses to identify locations where specific restoration project types have the greatest likelihood of working as intended because their function and design are matched with flooding and morphologic processes. The key premise is to identify whether a specific river analysis segment (length ~1-10 bankfull widths) within a longer reach is geomorphically active or inactive in the context of vertical and lateral stabilities, and hydrologically active for floodplain connectivity. Analyses involve empirical channel geometry relations, aerial photographic time series, LiDAR data, HEC-RAS hydraulic modeling, and a time-integrated sediment transport budget to evaluate trapping efficiency within each segment. The analysis segments are defined by HEC-RAS model cross sections. The results have been used effectively to identify feasible projects in a variety of alluvial gravel bed river reaches with lengths between 11 and 80 km and 2-year flood magnitudes between ~350 and 1330 m(3)/s. Projects constructed based on the results have all performed as planned. In addition, the results provide key criteria for formulating erosion and flood management plans. PMID:25910870

  17. A field experiment and numerical modeling of a tracer at a gravel beach in Prince William Sound, Alaska

    NASA Astrophysics Data System (ADS)

    Guo, Qiaona; Li, Hailong; Boufadel, Michel C.; Liu, Jin

    2014-08-01

    Oil from the 1989 Exxon Valdez oil spill persists in many gravel beaches in Prince William Sound (Alaska, USA), despite great remedial efforts. A tracer study using lithium at a gravel beach on Knight Island, Prince William Sound, during the summer of 2008 is reported. The tracer injection and transport along a transect were simulated using the two-dimensional numerical model MARUN. Model results successfully reproduced the tracer concentrations observed at wells along the transect. A sensitivity analysis revealed that the estimated parameters are well determined. The simulated spatial distribution of tracer indicated that nutrients applied along the transect for bioremediation purposes would be washed to the sea very quickly (within a semi-diurnal tidal cycle) by virtue of the combination of the two-layered beach structure, the tidal fluctuation and the freshwater flow from inland. Thus, pore-water samples in the transect were found to be clean due to factors other than bioremediation. This may explain why the oil did not persist within the transect.

  18. Geomorphic response to flow regulation and channel and floodplain alteration in the gravel-bedded Cedar River, Washington, USA

    NASA Astrophysics Data System (ADS)

    Gendaszek, Andrew S.; Magirl, Christopher S.; Czuba, Christiana R.

    2012-12-01

    Decadal- to annual-scale analyses of changes to the fluvial form and processes of the Cedar River in Washington State, USA, reveal the effects of flow regulation, bank stabilization, and log-jam removal on a gravel-bedded river in a temperate climate. During the twentieth century, revetments were built along ~ 60% of the lower Cedar River's length and the 2-year return period flow decreased by 47% following flow regulation beginning in 1914. The formerly wide, anastomosing channel narrowed by over 50% from an average of 47 m in 1936 to 23 m in 1989 and became progressively single threaded. Subsequent high flows and localized revetment removal contributed to an increase in mean channel width to about 34 m by 2011. Channel migration rates between 1936 and 2011 were up to 8 m/year in reaches not confined by revetments or valley walls and less than analysis uncertainty throughout most of the Cedar River's length where bank armoring restricted channel movement. In unconfined reaches where large wood and sediment can be recruited, contemporary high flows, though smaller in magnitude than preregulation high flows, form and maintain geomorphic features such as pools, gravel bars, and side channels. Reaches confined by revetments remain mostly unmodified in the regulated flow regime. While high flows are important for maintaining channel dynamics in the Cedar River, their effectiveness is currently reduced by revetments, limited sediment supply, the lack of large wood available for recruitment to the channel, and decreased magnitude since flow regulation.

  19. Characterization of metal adsorption variability in a sand and gravel aquifer, Cape Cod, Massachusetts, U.S.A

    USGS Publications Warehouse

    Fuller, C.C.; Davis, J.A.; Coston, J.A.; Dixon, E.

    1996-01-01

    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+) and zinc (Zn2+) adsorption at constant chemical conditions (pH 5.3) varied by a factor of 2 and 4, respectively. Pb2+ and Zn2+ were adsorbed primarily by Fe- and Al-oxide coatings on quartz-grain surfaces. Per unit surface area, both Pb2+ and Zn2+ adsorption were significantly correlated with the amount of Fe and Al that dissolved from the aquifer material in a partial chemical extraction. The variability in conditional binding constants for Pb2+ and Zn2+ adsorption (log KADS) derived from a simple non-electrostatic surface complexation model were also predicted by extracted Fe and Al normalized to surface area. Because the abundance of Fe- and Al-oxide coatings that dominate adsorption does not vary inversely with grain size by a simple linear relationship, only a weak, negative correlation was found between the spatial variability of Pb2+ adsorption and grain size in this aquifer. The correlation between Zn2+ adsorption and grain size was not significant. Partial chemical extractions combined with surface-area measurements have potential use for estimating metal adsorption variability in other sand and gravel aquifers of negligible carbonate and organic carbon content.

  20. A field experiment and numerical modeling of a tracer at a gravel beach in Prince William Sound, Alaska

    NASA Astrophysics Data System (ADS)

    Guo, Qiaona; Li, Hailong; Boufadel, Michel C.; Liu, Jin

    2014-12-01

    Oil from the 1989 Exxon Valdez oil spill persists in many gravel beaches in Prince William Sound (Alaska, USA), despite great remedial efforts. A tracer study using lithium at a gravel beach on Knight Island, Prince William Sound, during the summer of 2008 is reported. The tracer injection and transport along a transect were simulated using the two-dimensional numerical model MARUN. Model results successfully reproduced the tracer concentrations observed at wells along the transect. A sensitivity analysis revealed that the estimated parameters are well determined. The simulated spatial distribution of tracer indicated that nutrients applied along the transect for bioremediation purposes would be washed to the sea very quickly (within a semi-diurnal tidal cycle) by virtue of the combination of the two-layered beach structure, the tidal fluctuation and the freshwater flow from inland. Thus, pore-water samples in the transect were found to be clean due to factors other than bioremediation. This may explain why the oil did not persist within the transect.

  1. Relationships between woody vegetation and geomorphological patterns in three gravel-bed rivers with different intensities of anthropogenic disturbance

    NASA Astrophysics Data System (ADS)

    Sitzia, T.; Picco, L.; Ravazzolo, D.; Comiti, F.; Mao, L.; Lenzi, M. A.

    2016-07-01

    We compared three gravel-bed rivers in north-eastern Italy (Brenta, Piave, Tagliamento) having similar bioclimate, geology and fluvial morphology, but affected by different intensities of anthropogenic disturbance related particularly to hydropower dams, training works and instream gravel mining. Our aim was to test whether a corresponding difference in the interactions between vegetation and geomorphological patterns existed among the three rivers. In equally spaced and sized plots (n = 710) we collected descriptors of geomorphic conditions, and presence-absence of woody species. In the less disturbed river (Tagliamento), spatial succession of woody communities from the floodplain to the channel followed a profile where higher elevation floodplains featured more developed tree communities, and lower elevation islands and bars were covered by pioneer communities. In the intermediate-disturbed river (Piave), islands and floodplains lay at similar elevation and both showed species indicators of mature developed communities. In the most disturbed river (Brenta), all these patterns were simplified, all geomorphic units lay at similar elevations, were not well characterized by species composition, and presented similar persistence age. This indicates that in human-disturbed rivers, channel and vegetation adjustments are closely linked in the long term, and suggests that intermediate levels of anthropogenic disturbance, such as those encountered in the Piave River, could counteract the natural, more dynamic conditions that may periodically fragment vegetated landscapes in natural rivers.

  2. Assessment Approach for Identifying Compatibility of Restoration Projects with Geomorphic and Flooding Processes in Gravel Bed Rivers

    NASA Astrophysics Data System (ADS)

    DeVries, Paul; Aldrich, Robert

    2015-08-01

    A critical requirement for a successful river restoration project in a dynamic gravel bed river is that it be compatible with natural hydraulic and sediment transport processes operating at the reach scale. The potential for failure is greater at locations where the influence of natural processes is inconsistent with intended project function and performance. We present an approach using practical GIS, hydrologic, hydraulic, and sediment transport analyses to identify locations where specific restoration project types have the greatest likelihood of working as intended because their function and design are matched with flooding and morphologic processes. The key premise is to identify whether a specific river analysis segment (length ~1-10 bankfull widths) within a longer reach is geomorphically active or inactive in the context of vertical and lateral stabilities, and hydrologically active for floodplain connectivity. Analyses involve empirical channel geometry relations, aerial photographic time series, LiDAR data, HEC-RAS hydraulic modeling, and a time-integrated sediment transport budget to evaluate trapping efficiency within each segment. The analysis segments are defined by HEC-RAS model cross sections. The results have been used effectively to identify feasible projects in a variety of alluvial gravel bed river reaches with lengths between 11 and 80 km and 2-year flood magnitudes between ~350 and 1330 m3/s. Projects constructed based on the results have all performed as planned. In addition, the results provide key criteria for formulating erosion and flood management plans.

  3. The evolution of gravel bed channels after dam removal: Case study of the Anaconda and Union City Dam removals

    NASA Astrophysics Data System (ADS)

    Wildman, Laura A. S.; MacBroom, James G.

    2005-10-01

    The Anaconda and Union City Dams on the Naugatuck River in Connecticut were removed in February and October 1999. A detailed study of the sites prior to removal was undertaken including sediment testing and predictions of upstream channel formation post-dam removal. The 3.35-m-high timber crib/rock fill spillway of the Anaconda Dam partially breached during a storm prior to the dam's scheduled removal allowing a portion of the impounded sediment to move down through the river system. This event changed the removal plans and the remainder of the spillway was removed under an emergency order in the course of 4 days. The Union City Dam, a 2.44-m-high timber crib/rock fill dam capped with concrete and stone, was removed on schedule. A portion of the impounded sediment was removed by mechanical means during the deconstruction of the structure. The evolution of the two upstream channels post-project provided unique challenges and valuable insights as to what kind of channel transition can be expected in gravel bed river systems after a low head dam has been removed. This paper describes the initial engineering analysis and design, the subsequent removal of the two dams, and compares observations on the transition of the upstream channels following dam removal to the initial engineering predictions and other models. The relatively steep gravel bed channels evolved in a predictable manner, except where anthropogenic barriers (sanitary sewer, rock weir) interrupted.

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

    USGS Publications Warehouse

    Herrick, J.E.; Van Zee, J. W.; Belnap, J.; Johansen, J.R.; Remmenga, M.

    2010-01-01

    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 infiltration rate and total infiltration and increased sediment generation from small (0.5m2) rainfall simulation plots (p<0.01). Trampling had no effect on time to runoff or time to peak runoff. Trampling had similar effects at sites with both low and very low levels of cyanobacterial biomass, as indicated by chlorophyll a concentrations. We concluded that trampling effects are relatively independent of differences in the relatively low levels of cyanobacterial biomass in this environment. Instead, trampling appears to reduce infiltration by significantly reducing the cover of gravel and coarse sand on the soil surface, facilitating the development of a physical crust during rainfall events. The results of this study underscore the importance of carefully characterizing both soil physical and biological properties to understand how disturbance affects ecosystem processes. ?? 2010.

  5. Retardation of ammonium and potassium transport through a contaminated sand and gravel aquifer: The Role of cation exchange

    USGS Publications Warehouse

    Ceazan, M.L.; Thurman, E.M.; Smith, R.L.

    1989-01-01

    The role of cation exchange in the retardation of ammonium (NH4+) and potassium (K+) transport in a shallow sand and gravel aquifer was evaluated by use of observed distributions of NH4+ and K+ within a plume of sewage-contaminated groundwater, small-scale tracer injection tests, and batch sorption experiments on aquifer material. Both NH4+ and K+ were transported ???2 km in the 4-km-long contaminant plume (retardation factor, Rf = 2.0). Sediments from the NH4+-containing zone of the plume contained significant quantities of KCl-extractable NH4+ (extraction distribution coefficient, Kd,extr = 0.59-0.87 mL/g of dry sediment), and when added to uncontaminated sediments, NH4+ sorption followed a linear isotherm. Small-scale tracer tests demonstrated that NH4+ and K+ were retarded (Rf =3.5) relative to a nonreactive tracer (Br-). Sorption of dissolved NH4+ was accompanied by concomitant release of calcium (Ca2+), magnesium (Mg2+), and sodium (Na+) from aquifer sediments, suggesting involvement of cation exchange. In contrast, nitrate (NO3-) was not retarded and cleanly separated from NH4+ and K+ in the small-scale tracer tests. This study demonstrates that transport of NH4+ and K+ through a sand and gravel aquifer can be markedly affected by cation-exchange processes even at a clay content less than 0.1%.

  6. Geometry of meandering and braided gravel-bed threads from the Bayanbulak Grassland, Tianshan, P. R. China

    NASA Astrophysics Data System (ADS)

    Métivier, François; Devauchelle, Olivier; Chauvet, Hugo; Lajeunesse, Eric; Meunier, Patrick; Blanckaert, Koen; Ashmore, Peter; Zhang, Zhi; Fan, Yuting; Liu, Youcun; Dong, Zhibao; Ye, Baisheng

    2016-03-01

    The Bayanbulak Grassland, Tianshan, P. R. China, is located in an intramontane sedimentary basin where meandering and braided gravel-bed rivers coexist under the same climatic and geological settings. We report and compare measurements of the discharge, width, depth, slope and grain size of individual threads from these braided and meandering rivers. 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 rivers. 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 threads. This suggests that a braided river is a collection of intertwined threads, which individually resemble those of meandering rivers. Given the environmental conditions in Bayanbulak, we furthermore hypothesize that bedload transport causes the threads to be wider than predicted by the threshold theory.

  7. Geomorphic response to flow regulation and channel and floodplain alteration in the gravel-bedded Cedar River, Washington, USA

    USGS Publications Warehouse

    Gendaszek, Andrew S.; Magirl, Christopher S.; Czuba, Christiana R.

    2012-01-01

    Decadal- to annual-scale analyses of changes to the fluvial form and processes of the Cedar River in Washington State, USA, reveal the effects of flow regulation, bank stabilization, and log-jam removal on a gravel-bedded river in a temperate climate. During the twentieth century, revetments were built along ~ 60% of the lower Cedar River's length and the 2-year return period flow decreased by 47% following flow regulation beginning in 1914. The formerly wide, anastomosing channel narrowed by over 50% from an average of 47 m in 1936 to 23 m in 1989 and became progressively single threaded. Subsequent high flows and localized revetment removal contributed to an increase in mean channel width to about 34 m by 2011. Channel migration rates between 1936 and 2011 were up to 8 m/year in reaches not confined by revetments or valley walls and less than analysis uncertainty throughout most of the Cedar River's length where bank armoring restricted channel movement. In unconfined reaches where large wood and sediment can be recruited, contemporary high flows, though smaller in magnitude than preregulation high flows, form and maintain geomorphic features such as pools, gravel bars, and side channels. Reaches confined by revetments remain mostly unmodified in the regulated flow regime. While high flows are important for maintaining channel dynamics in the Cedar River, their effectiveness is currently reduced by revetments, limited sediment supply, the lack of large wood available for recruitment to the channel, and decreased magnitude since flow regulation.

  8. Geospatial organization of fluvial landforms in a gravel-cobble river: Beyond the riffle-pool couplet

    NASA Astrophysics Data System (ADS)

    Wyrick, J. R.; Pasternack, G. B.

    2014-05-01

    Morphological units (MU) are landforms with distinct local form-process associations at ~ 1-10 channel widths scale that may be the fundamental building blocks describing the geomorphic structure of a river. Past research has disproportionately focused on the two MUs of pool and riffle, conjecturing that they are the central linked couplet in the process-form association. The goal of this study was to delineate and map spatially explicit fluvial landforms in two-dimensional planview within a gravel-cobble bed river using two-dimensional hydrodynamic delineation and then to statistically examine MU geospatial patterns for indicators of deterministic geomorphic control. This procedure is not discharge-dependent like mesohabitat methods, but gets at the geometry of underlying landforms. Statistical testing confirmed that eight delineated in-channel MU types comprise a complex and diverse channel morphology in which pools and riffles are not directly coupled. Specifically, gravel-cobble river channels (1) exhibit nonrandom spatial organization of their longitudinally and laterally variable landform morphology; (2) consist of a variety of MU types, not just pools and riffles; and (3) show distinct MU collocations and avoidances, with riffles linked to chutes and runs, while pools are linked to slackwaters and glides. Planview MU delineation with two-dimensional hydrodynamic modeling provides a 'bottom-up' approach to understanding and linking channel morphology with ecosystem services and geomorphic processes and is being used to guide river management and rehabilitation strategies.

  9. Regulated flushing in a gravel-bed river for channel habitat maintenance: A Trinity River fisheries case study

    NASA Astrophysics Data System (ADS)

    Nelson, R. Wayne; Dwyer, John R.; Greenberg, Wendy E.

    1987-08-01

    The operation of Trinity and Lewiston Dams on the Trinity River in northern California in the United States, combined with severe watershed erosion, has jeopardized the existence of prime salmonid fisheries. Extreme streamflow depletion and stream sedimentation below Lewiston have resulted in heavy accumulation of coarse sediment on riffle gravel and filling of streambed pools, causing the destruction of spawning, nursery, and overwintering habitat for prized chinook salmon ( Salmo gairdnerii) and steelhead trout ( Oncorhynchus tschawytscha). Proposals to restore and maintain the degraded habitat include controlled one-time remedial peak flows or annual maintenance peak flows designed to flush the spawning gravel and scour the banks, deltas, and pools. The criteria for effective channel restoration or maintenance by streambed flushing and scouring are examined here, as well as the mechanics involved. The liabilities of releasing mammoth scouring-flushing flows approximating the magnitude that preceded reservoir construction make this option unviable. The resulting damage to fish habitat established under the postproject streamflow regime, as well as damage to human settlements in the floodplain, would be unacceptable, as would the opportunity costs to hydroelectric and irrigation water users. The technical feasibility of annual maintenance flushing flows depends upon associated mechanical and structural measures, particularly instream maintenance dredging of deep pools and construction of a sediment control dam on a tributary where watershed erosion is extreme. The cost effectiveness of a sediment dam with a limited useful economic life, combined with perpetual maintenance dredging, is questionable.

  10. Low-pass filtered continuum streambed and bedload sediment mass balance laws for an alluvial, gravel-bed stream

    NASA Astrophysics Data System (ADS)

    DeTemple, B.; Wilcock, P.

    2011-12-01

    In an alluvial, gravel-bed stream governed by a plane-bed bedload transport regime, the physicochemical properties, size distribution, and granular architecture of the sediment grains that constitute the streambed surface influence many hydrodynamic, geomorphic, chemical, and ecological processes. Consequently, the abilities to accurately characterize the morphology and model the morphodynamics of the streambed surface and its interaction with the bedload above and subsurface below are necessary for a more complete understanding of how sediment, flow, organisms, and biogeochemistry interact. We report on our progress in the bottom-up development of low-pass filtered continuum streambed and bedload sediment mass balance laws for an alluvial, gravel-bed stream. These balance laws are assembled in a four stage process. First, the stream sediment-water system is conceptually abstracted as a nested, multi-phase, multi-species, structured continuum. Second, the granular surface of an aggregate of sediment grains is mathematically defined. Third, an integral approach to mass balance, founded in the continuum theory of multiphase flow, is used to formulate primordial, differential, instantaneous, local, continuum, mass balance laws applicable at any material point within a gravel-bed stream. Fourth, area averaging and time-after-area averaging, employing planform, low-pass filtering expressed as correlation or convolution integrals and based on the spatial and temporal filtering techniques found in the fields of multiphase flow, porous media flow, and large eddy simulation of turbulent fluid flow, are applied to smooth the primordial equations while maximizing stratigraphic resolution and preserving the definitions of relevant morphodynamic surfaces. Our approach unifies, corrects, contextualizes, and generalizes prior efforts at developing stream sediment continuity equations, including the top-down derivations of the surface layer (or "active layer") approach of Hirano

  11. Sedimentology of rocky shorelines: 1. A review of the problem, with analytical methods, and insights gained from the Hulopoe Gravel and the modern rocky shoreline of Lanai, Hawaii

    NASA Astrophysics Data System (ADS)

    Felton, E. Anne

    2002-10-01

    Hypotheses advanced concerning the origin of the Pleistocene Hulopoe Gravel on Lanai include mega-tsunami, abandoned beach, 'multiple event,' rocky shoreline, and for parts of the deposit, Native Hawaiian constructions and degraded lava flow fronts. Uplift of Lanai shorelines has been suggested for deposits occurring up to at least 190 m. These conflicting hypotheses highlight problems with the interpretation of coarse gravel deposits containing marine biotic remains. The geological records of the processes implied by these hypotheses should look very different. Discrimination among these or any other hypotheses for the origins of the Hulopoe Gravel will require careful study of vertical and lateral variations in litho- and biofacies, facies architecture, contact relationships and stratal geometries of this deposit. Observations of modern rocky shorelines, particularly on Lanai adjacent to Hulopoe Gravel outcrops, have shown that distinctive coarse gravel facies are present, several of which occur in specific geomorphic settings. Tectonic, isostatic and eustatic changes which cause rapid shoreline translations on steep slopes favour preservation of former rocky shorelines and associated sedimentary deposits both above and below sea level. The sedimentary record of those shorelines is likely to be complex. The modern rocky shoreline sedimentary environment is a hostile one, largely neglected by sedimentologists. A range of high-energy processes characterize these shorelines. Long-period swell, tsunami and storm waves can erode hard bedrock and generate coarse gravel. They also erode older deposits, depositing fresh ones containing mixtures of materials of different ages. Additional gravelly material may be contributed by rivers draining steep hinterlands. To fully evaluate rocky shoreline deposition in the broadest sense, for both the Hulopoe Gravel and other deposits, sedimentary facies models are needed for rocky shorelines occurring in a range of settings

  12. Map showing potential sources of gravel and crushed-rock aggregate in the greater Denver area, Front Range urban corridor, Colorado

    USGS Publications Warehouse

    Trimble, D.E.; Fitch, H.R.

    1974-01-01

    Gravel and (or) crushed-rock aggregates are essential commodities for urban development, but supplies in many places are exhausted or otherwise eliminated by urban growth. Gravel resources may be exhausted by exploitation, covered by urban spread, or eliminated from production by zoning. this conflict between a growing need and a progressively reduced supply can be forestalled by informed land-use planning. Fundamental to intelligent decisions on land use is knowledge of the physical character, distribution, and quantity of the gravel resources of an area, and of the alternative resource of rock suitable for crushing. This map has been prepared to supply data basic to land-use planning in the Front Range Urban Corridor.

  13. Filtration and transport of Bacillus subtilis spores and the F-RNA phage MS2 in a coarse alluvial gravel aquifer: Implications in the estimation of setback distances

    NASA Astrophysics Data System (ADS)

    Pang, Liping; Close, Murray; Goltz, Mark; Noonan, Mike; Sinton, Lester

    2005-04-01

    Filtration of Bacillus subtilis spores and the F-RNA phage MS2 (MS2) on a field scale in a coarse alluvial gravel aquifer was evaluated from the authors' previously published data. An advection-dispersion model that is coupled with first-order attachment kinetics was used in this study to interpret microbial concentration vs. time breakthrough curves (BTC) at sampling wells. Based on attachment rates ( katt) that were determined by applying the model to the breakthrough data, filter factors ( f) were calculated and compared with f values estimated from the slopes of log ( cmax/ co) vs. distance plots. These two independent approaches resulted in nearly identical filter factors, suggesting that both approaches are useful in determining reductions in microbial concentrations over transport distance. Applying the graphic approach to analyse spatial data, we have also estimated the f values for different aquifers using information provided by some other published field studies. The results show that values of f, in units of log ( cmax/ co) m -1, are consistently in the order of 10 -2 for clean coarse gravel aquifers, 10 -3 for contaminated coarse gravel aquifers, and generally 10 -1 for sandy fine gravel aquifers and river and coastal sand aquifers. For each aquifer category, the f values for bacteriophages and bacteria are in the same order-of-magnitude. The f values estimated in this study indicate that for every one-log reduction in microbial concentration in groundwater, it requires a few tens of meters of travel in clean coarse gravel aquifers, but a few hundreds of meters in contaminated coarse gravel aquifers. In contrast, a one-log reduction generally only requires a few meters of travel in sandy fine gravel aquifers and sand aquifers. Considering the highest concentration in human effluent is in the order of 10 4 pfu/l for enteroviruses and 10 6 cfu/100 ml for faecal coliform bacteria, a 7-log reduction in microbial concentration would comply with the drinking

  14. Effects of a physico-chemical treatment of a dredged sediment on its ecotoxicity after discharge in laboratory gravel pit microcosms.

    PubMed

    Clément, Bernard; Vaille, Gilles; Moretto, Robert; Vernus, Emmanuel; Abdelghafour, Mohammed

    2010-03-15

    In France, dredged sediments may be dumped into submerged gravel pits. As a consequence, adverse effects may be expected. In addition, groundwater quality may be impacted due to hydraulic communications with gravel pits. The immersion of dredged sediments into gravel pits should thus be restricted to clean or slightly contaminated sediments to minimize the impacts on aquatic ecosystems and human safe. For highly contaminated sediments, alternatives may be treatments aiming at removing or/and neutralizing contaminants. The Novosol treatment was aimed at neutralizing metals by complexation with orthophosphoric acid and discarding organic pollutants by calcination. The efficiency of the Novosol treatment was assessed in a scenario of sediment immersion into experimental laboratory gravel pits (LGP). A 180L water compartment was set up in each system so as to simulate the gravel pit, and various living organisms were introduced. Following a period of colonization and stabilization, raw and treated sediments were introduced into two different LGPs, and the fate and effects of pollutants were studied during the period of deposition and post-deposition. The treatment had positive effects on survival and development of benthic populations and reproduction of pond snails but the introduction of the treated sediment was followed by an increase in salinity (phosphates, sulphates) and a peak of hexavalent chromium at concentrations above drinkability limits and likely to have impaired invertebrate populations of the water column. The results of this study suggest that discharge of contaminated sediments at a high solid:liquid ratio (1:10) in gravel pits or equivalent aquatic ecosystems may have only limited effects on biota and ground water quality. The Novosol treatment should, however, be improved so as to increase efficiency of oxidised chromium complexation during the phosphatation step. PMID:19879042

  15. Geomorphic controls on fine sediment reinfiltration into salmonid spawning gravels and the implications for spawning habitat rehabilitation

    NASA Astrophysics Data System (ADS)

    Franssen, Jan; Lapointe, Michel; Magnan, Pierre

    2014-04-01

    Anthropogenic activities often increase the flux of fine sediment to fluvial environments. In gravel-bed streams the extent to which augmented fines loading causes the degradation of vital interstitial habitats is determined by factors controlling fines infiltration into channel substratum. Previous research suggests that substrate pore constriction size, intensity of upwelling interstitial flow, and the quantity of fines transported across the bed surface (i.e., exposure dose) are three important factors controlling substrate fines content. Few field studies have investigated the interactive effects of these physical factors. We constructed 17 experimental redds in brook trout spawning microhabitats in a boreal forest stream in Quebec, Canada, to investigate the role of pore constriction size, hyporheic flow, and exposure dose on substrate fines content. To simulate the effect of spawning in coarsening the substrates, redds were partially cleaned of coarse sand and of all fine sediment (< 0.5 mm). Results show that coarse sands and fine gravel (0.5-4 mm; filter class) acted as a filter of percolating fine sediment (< 0.5 mm). We found that this filtering effect (i.e., lower fines density at egg pocket depth) occurred at sites where the proportion of the filter class in the substratum above egg pocket depth exceeded a threshold value of 18%, as indicated by a statistically significant step-function response between fines gradient with depth and the filter class content in the uppermost layers of the bed. Results also indicated that fines content at depth was unrelated to fines exposure. Estimated upward seepage rates were well below the threshold velocity that would inhibit the percolation of medium-grained sand (i.e., 0.5 mm) into the bed. These results suggest that within these gravel-bed spawning substrates the abundance of filter classes was the primary determinant of fines content at depth. This study highlights the importance of considering filter class

  16. Coupling Hydrodynamic Modeling and Empirical Measures of Bed Mobility: Implications for Restoring Spawning Gravel Quality on a Large Regulated River

    NASA Astrophysics Data System (ADS)

    May, C. L.; Smith, B. J.; Lisle, T. E.; Lang, M. M.

    2005-05-01

    Flow releases are increasingly being used as a tool to restore spawning gravel quality downstream of large dams. Often times, the primary goal of a peak flow release is to flush fine sediment from incubation habitat and restore active river processes; thus understanding the portion of the bed that is entrained and the flow required for full mobility is important. However, a critical knowledge gap for implementing these experimental floods is predicting the potential scouring of spawning redds in downstream reaches. To address these questions we need to understand the relationships between river discharge, bed mobility, and scour depths in areas heavily utilized by spawning salmon. Our approach couples numerical flow modeling and empirical data to quantify spatially explicit zones of differential bed mobility and identify specific areas where scour is deep enough to impact redd viability. Boundary shear stress values were predicted using the USGS's Multi-Dimensional Surface Water Modeling System for a segment of the Trinity River below Lewiston Dam. From model-generated shear stress and fine-scale mapping of local particle size distributions, Shields stress values were calculated to identify areas of differential bed mobility. Our data suggest that full mobility is limited to a central, yet discontinuous core along the thalweg, which expands with increasing flow strengths. Spatial analysis revealed that Chinook salmon tend not to spawn in areas that became fully mobile during bankfull flood events. Scour depths in areas preferentially used for spawning were less than in other portions of the bed and were not deep enough to impact incubating eggs or embryos. This site-selection preference allows fish to spawn in areas that are relatively safe from deep scour. However, the trade-off for spawning in stable areas is that flushing of fine sediment from the subsurface occurs very infrequently and gravel permeability is likely to become limiting for egg and embryo survival

  17. Water budgets of Italian and Dutch gravel pit lakes: a study using a fen as a natural evaporation pan, stable isotopes and conservative tracer modeling.

    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 where the gravel pits are below the water table and fill with groundwater. Their presence changes the drainage patterns, water- and hydrochemical budgets of a watershed. We have studied the water budget of two gravel pit lakes systems using stable H and O isotopes of water as well as conservative tracer (Cl) modeling. The Dutch gravel pit lakes are a fluvial fresh water system of 70 lakes along the Meuse River and the Italian gravel pit lakes are a brackish system along the Adriatic coast. Surface water evaporation from the gravel pit lakes is larger than the actual evapotranspiration of the grass land and forests that were replaced. The ratio of evaporation to total flow into the Dutch lakes was determined by using a Fen as a natural evaporation pan: the isotope content of the Tuspeel Fen, filled with rain water and sampled in a dry and warm summer period (August 2012), is representative for the limiting isotopic enrichment under local hydro meteorological conditions. The Local Evaporation line (LEL) was determined δ2 H = 4.20 δ 18O - 14.10 (R² = 0.99) and the ratio of total inflow to evaporation for three gravel pit lakes were calculated to be 22.6 for the De Lange Vlieter lake used for drinking water production, 11.3 for the Boschmolen Lake and 8.9 for the Anna's Beemd lake showing that groundwater flow is much larger than evaporation. The Italian gravel pit lakes are characterized by high salinity (TDS = 4.6-12.3 g L-1). Stable isotope data show that these latter gravel pit lakes are fed by groundwater, which is a mix between fresh Apennine River water and brackish (Holocene) Adriatic Sea water. The local evaporation line is determined: δ2H = 5.02 δ18O - 10.49. The ratio of total inflow to evaporation is 5. Conservative tracer modeling indicates that the chloride concentration in the Italian gravel pit lakes stabilizes after a short period of rapid

  18. Mechanisms of vegetation removal by floods on bars of a heavily managed gravel bed river (The Isere River, France)

    NASA Astrophysics Data System (ADS)

    Jourdain, Camille; Belleudy, Philippe; Tal, Michal; Malavoi, Jean-René

    2016-04-01

    In natural alpine gravel bed rivers, floods and their associated bedload transport maintain channels active and free of mature woody vegetation. In managed rivers, where flood regime and sediment supply have been modified by hydroelectric infrastructures and sediment mining, river beds tend to stabilize. As a result, in the recent past, mature vegetation has established on gravel bars of many gravel bed rivers worldwide. This established vegetation increases the risk of flooding by decreasing flow velocity and increasing water levels. In addition, the associated reduction in availability of pioneer habitats characteristic of these environments typically degrades biodiversity. Managing hydrology in a way that would limit vegetation establishment on bars presents an interesting management option. In this context, our study aims at understanding the impacts of floods of varying magnitude on vegetation removal, and identifying and quantifying the underlying mechanisms. Our study site is the Isère River, a heavily managed gravel bed river flowing in the western part of the French Alps. We studied the impact of floods on sediment transport and vegetation survival at the bar scale through field monitoring from 2014 to 2015, focusing on young salicaceous vegetation (<2 yr old). Measurements were made before and after floods. Vegetation was monitored on 16m² plots through repeat photographs. Sediment transport was assessed using painted plots, scour chains, and topographic surveys. Hourly water discharge was obtained from the national gauging network. The hydraulics of monitored floods was characterized using a combination of field measurements and 2D hydraulic modeling: water levels were measured with pressure sensors and Large Scale Particle Velocimetry was used to measure flow velocities. These data were used to calibrate 2D hydrodynamic model using TELEMAC2D. At the reach scale, removal of mature vegetation was assed using a series of historical aerial photographs

  19. Aerodynamic roughness height for gravel-mantled megaripples, with implications for wind profiles near TARs on Mars

    NASA Astrophysics Data System (ADS)

    Zimbelman, J. R.; Scheidt, S. P.; de Silva, S. L.; Bridges, N. T.; Spagnuolo, M. G.; Neely, E. M.

    2016-03-01

    Aerodynamic roughness heights of 1-3 cm were obtained from measured wind profiles collected among fields of gravel-mantled megaripples in the high desert of the Puna region of northwestern Argentina. Roughness height appears to be relatively insensitive to the angle at which the wind was incident upon the bedforms throughout the study sites. The results represent the first wind profiling measurements for large megaripples, but they also demonstrate the importance of a careful evaluation of many potential effects that can influence the utility of wind profiling data. The same effects that influence collection of fieldwork data must also be considered in any prediction of wind profiles anticipated to occur near Transverse Aeolian Ridges and other aeolian features on Mars that are intermediate in scale between wind ripples and small sand dunes.

  20. Cilioprotists as biological indicators for estimating the efficiency of using Gravel Bed Hydroponics System in domestic wastewater treatment.

    PubMed

    El-Serehy, Hamed A; Bahgat, Magdy M; Al-Rasheid, Khaled; Al-Misned, Fahad; Mortuza, Golam; Shafik, Hesham

    2014-07-01

    Interest has increased over the last several years in using different methods for treating sewage. The rapid population growth in developing countries (Egypt, for example, with a population of more than 87 millions) has created significant sewage disposal problems. There is therefore a growing need for sewage treatment solutions with low energy requirements and using indigenous materials and skills. Gravel Bed Hydroponics (GBH) as a constructed wetland system for sewage treatment has been proved effective for sewage treatment in several Egyptian villages. The system provided an excellent environment for a wide range of species of ciliates (23 species) and these organisms were potentially very useful as biological indicators for various saprobic conditions. Moreover, the ciliates provided excellent means for estimating the efficiency of the system for sewage purification. Results affirmed the ability of this system to produce high quality effluent with sufficient microbial reduction to enable the production of irrigation quality water. PMID:24955010

  1. Cilioprotists as biological indicators for estimating the efficiency of using Gravel Bed Hydroponics System in domestic wastewater treatment

    PubMed Central

    El-Serehy, Hamed A.; Bahgat, Magdy M.; Al-Rasheid, Khaled; Al-Misned, Fahad; Mortuza, Golam; Shafik, Hesham

    2013-01-01

    Interest has increased over the last several years in using different methods for treating sewage. The rapid population growth in developing countries (Egypt, for example, with a population of more than 87 millions) has created significant sewage disposal problems. There is therefore a growing need for sewage treatment solutions with low energy requirements and using indigenous materials and skills. Gravel Bed Hydroponics (GBH) as a constructed wetland system for sewage treatment has been proved effective for sewage treatment in several Egyptian villages. The system provided an excellent environment for a wide range of species of ciliates (23 species) and these organisms were potentially very useful as biological indicators for various saprobic conditions. Moreover, the ciliates provided excellent means for estimating the efficiency of the system for sewage purification. Results affirmed the ability of this system to produce high quality effluent with sufficient microbial reduction to enable the production of irrigation quality water. PMID:24955010

  2. The role of attached kelp (seaweed) fronds in lowering threshold of coarse gravel entrainment in tidal flows.

    NASA Astrophysics Data System (ADS)

    Carling, Paul

    2014-05-01

    There is a long history of reports of attached kelp (seaweed) fronds aiding entrainment of coarse sediment by flotation. In the intertidal zone of the Severn Estuary (UK) cobbles were observed to overpass fine gravel plane-beds and pebble-gravel dunes in those instances where seaweed fronds were attached. However, overpassing clasts without attached fronds were rare. Flume experiments were conducted to measure the reduction in velocity and shear stresses required for initial motion when fronds were attached. A range of factors influence entrainment including the ratio of seaweed weight:clast weight and length:width ratio of the seaweed frond. Reynolds stresses for entrainment, and the critical velocity for entrainment were reduced by around a factor of two for attached fronds in contrast to stones without fronds. Reductions in the critical velocity were associated with an increase in the values of drag coefficients for clasts with attached fronds; the majority of the drag being associated with the frond widths rather than the frond lengths. The significance of this study is manifold with respect to deposition of outsized clasts in the modern marine environment and in the geological record. The reduced entrainment values explain the presence of large clasts in near-shore and off-shore environments where measured velocities otherwise are not competent. In addition, when clasts are deposited and buried by sediment the seaweed fronds decay and so the role of kelp is not immediately evident. Thus in the geological marine sedimentary record buried outsized clasts may be related to kelp transport in some instances.

  3. Influence of colloids on the attenuation and transport of phosphorus in alluvial gravel aquifer and vadose zone media.

    PubMed

    Pang, Liping; Lafogler, Mark; Knorr, Bastian; McGill, Erin; Saunders, Darren; Baumann, Thomas; Abraham, Phillip; Close, Murray

    2016-04-15

    Phosphorous (P) leaching (e.g., from effluents, fertilizers) and transport in highly permeable subsurface media can be an important pathway that contributes to eutrophication of receiving surface waters as groundwater recharges the base-flow of surface waters. Here we investigated attenuation and transport of orthophosphate-P in gravel aquifer and vadose zone media in the presence and absence of model colloids (Escherichia coli, kaolinite, goethite). Experiments were conducted using repacked aquifer media in a large column (2m long, 0.19m in diameter) and intact cores (0.4m long, 0.24m in diameter) of vadose zone media under typical field flow rates. In the absence of the model colloids, P was readily traveled through the aquifer media with little attenuation (up to 100% recovery) and retardation, and P adsorption was highly reversible. Conversely, addition of the model colloids generally resulted in reduced P concentration and mass recovery (down to 28% recovery), and increased retardation and adsorption irreversibility in both aquifer and vadose zone media. The degree of colloid-assisted P attenuation was most significant in the presence of fine material and Fe-containing colloids at low flow rate but was least significant in the presence of coarse gravels and E. coli at high flow rate. Based on the experimental results, setback distances of 49-53m were estimated to allow a reduction of P concentrations in groundwater to acceptable levels in the receiving water. These estimates were consistent with field observations in the same aquifer media. Colloid-assisted P attenuation can be utilized to develop mitigation strategies to better manage effluent applications in gravelly soils. To efficiently retain P within soil matrix and reduce P leaching to groundwater, it is recommended to select soils that are rich in iron oxides, to periodically disturb soil preferential flow paths by tillage, and to apply a low irrigation rate. PMID:26803685

  4. Variation in the reference Shields stress for bed load transport in gravel-bed streams and rivers

    USGS Publications Warehouse

    Mueller, E.R.; Pitlick, J.; Nelson, J.M.

    2005-01-01

    The present study examines variations in the reference shear stress for bed load transport (??r) using coupled measurements of flow and bed load transport in 45 gravel-bed streams and rivers. The study streams encompass a wide range in bank-full discharge (1-2600 m3/s), average channel gradient (0.0003-0.05), and median surface grain size (0.027-0.21 m). A bed load transport relation was formed for each site by plotting individual values of the dimensionless transport rate W* versus the reach-average dimensionless shear stress ??*. The reference dimensionless shear stress ??r* was then estimated by selecting the value of ??* corresponding to a reference transport rate of W* = 0.002. The results indicate that the discharge corresponding to ?? r* averages 67% of the bank-full discharge, with the variation independent of reach-scale morphologic and sediment properties. However, values of ??r* increase systematically with average channel gradient, ranging from 0.025-0.035 at sites with slopes of 0.001-0.006 to values greater than 0.10 at sites with slopes greater than 0.02. A corresponding relation for the bank-full dimensionless shear stress ??bf*, formulated with data from 159 sites in North America and England, mirrors the relation between ??r* and channel gradient, suggesting that the bank-full channel geometry of gravel- and cobble-bedded streams is adjusted to a relatively constant excess shear stress, ??bf* - ??r*, across a wide range of slopes. Copyright 2005 by the American Geophysical Union.

  5. Estimations of soil fertility in physically degraded agricultural soils through selective accounting of fine earth and gravel fractions

    NASA Astrophysics Data System (ADS)

    Nagaraja, Mavinakoppa S.; Bhardwaj, Ajay Kumar; Prabhakara Reddy, G. V.; Srinivasamurthy, Chilakunda A.; Kumar, Sandeep

    2016-06-01

    Soil fertility and organic carbon (C) stock estimations are crucial to soil management, especially that of degraded soils, for productive agricultural use and in soil C sequestration studies. Currently, estimations based on generalized soil mass (hectare furrow basis) or bulk density are used which may be suitable for normal agricultural soils, but not for degraded soils. In this study, soil organic C, available nitrogen (N), available phosphorus (P2O5) and available potassium (K2O), and their stocks were estimated using three methods: (i) generalized soil mass (GSM, 2 million kg ha-1 furrow soil), (ii) bulk-density-based soil mass (BDSM) and (iii) the proportion of fine earth volume (FEV) method, for soils sampled from physically degraded lands in the eastern dry zone of Karnataka State in India. Comparative analyses using these methods revealed that the soil organic C, N, P2O and K2O stocks determined by using BDSM were higher than those determined by the GSM method. The soil organic C values were the lowest in the FEV method. The GSM method overestimated soil organic C, N, P2O and K2O by 9.3-72.1, 9.5-72.3, 7.1-66.6 and 9.2-72.3 %, respectively, compared to FEV-based estimations for physically degraded soils. The differences among the three methods of estimation were lower in soils with low gravel content and increased with an increase in gravel volume. There was overestimation of soil organic C and soil fertility with GSM and BDSM methods. A reassessment of methods of estimation was, therefore, attempted to provide fair estimates for land development projects in degraded lands.

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

    NASA Astrophysics Data System (ADS)

    Lea, Devin M.; Legleiter, Carl J.

    2016-01-01

    Stream power represents the rate of energy expenditure along a river and can be calculated using topographic data acquired via remote sensing or field surveys. This study sought to quantitatively relate temporal changes in the form of Soda Butte Creek, a gravel-bed river in northeastern Yellowstone National Park, to stream power gradients along an 8-km reach. Aerial photographs from 1994 to 2012 and ground-based surveys were used to develop a locational probability map and morphologic sediment budget to assess lateral channel mobility and changes in net sediment flux. A drainage area-to-discharge relationship and DEM developed from LiDAR data were used to obtain the discharge and slope values needed to calculate stream power. Local and lagged relationships between mean stream power gradient at median peak discharge and volumes of erosion, deposition, and net sediment flux were quantified via spatial cross-correlation analyses. Similarly, autocorrelations of locational probabilities and sediment fluxes were used to examine spatial patterns of sediment sources and sinks. Energy expended above critical stream power was calculated for each time period to relate the magnitude and duration of peak flows to the total volumetric change in each time increment. Collectively, we refer to these methods as the stream power gradient (SPG) framework. The results of this study were compromised by methodological limitations of the SPG framework and revealed some complications likely to arise when applying this framework to small, wandering, gravel-bed rivers. Correlations between stream power gradients and sediment flux were generally weak, highlighting the inability of relatively simple statistical approaches to link sub-budget cell-scale sediment dynamics to larger-scale driving forces such as stream power gradients. Improving the moderate spatial resolution techniques used in this study and acquiring very-high resolution data from recently developed methods in fluvial remote

  7. Transport of Escherichia coli and F-RNA bacteriophages in a 5 m column of saturated pea gravel

    NASA Astrophysics Data System (ADS)

    Sinton, Lester W.; Mackenzie, Margaret L.; Karki, Naveena; Braithwaite, Robin R.; Hall, Carollyn H.; Flintoft, Mark J.

    2010-09-01

    The relative transport and attenuation of bacteria, bacteriophages, and bromide was determined in a 5 m long × 0.3 m diameter column of saturated pea gravel. The velocity ( V), longitudinal dispersivity ( αx) and total removal rate ( λ) were calculated from the breakthrough curves at 1 m, 3 m, and 5 m, at a flow rate of 32 L h - 1 . Inactivation ( μ) rates were determined in survival chambers. Two pure culture experiments with Escherichia coli J6-2 and F-RNA phage MS2 produced an overall V ranking of E. coli J6-2 > MS2 > bromide, consistent with velocity enhancement, whereby larger particles progressively move into faster, central streamlines of saturated pores. Removal rates were near zero for MS2, but were higher for E. coli J6-2. In two sewage experiments, E. coli and F-RNA phage Vs were similar (but > bromide). This was attributed to phage adsorption to colloids similar in size to E. coli cells. Sewage phage removal rates were higher than for the pure MS2 cultures. The application of filtration theory suggested that, whereas free phage were unaffected by settling, this was the primary removal mechanism for the colloid-associated phage. However, cultured and sewage E. coli removal rates were similar, suggesting the dominance of free E. coli cells in the sewage. When MS2 was attached to kaolin particles, it was transported faster than free MS2, but at similar rates to sewage phage. The μ values indicated little contribution of inactivation to removal of either cultured or sewage microorganisms. The results showed the importance of association with colloids in determining the relative transport of bacteria and viruses in gravels.

  8. Pharmaceuticals, perfluorosurfactants, and other organic wastewater compounds in public drinking water wells in a shallow sand and gravel aquifer.

    PubMed

    Schaider, Laurel A; Rudel, Ruthann A; Ackerman, Janet M; Dunagan, Sarah C; Brody, Julia Green

    2014-01-15

    Approximately 40% of U.S. residents rely on groundwater as a source of drinking water. Groundwater, especially unconfined sand and gravel aquifers, is vulnerable to contamination from septic systems and infiltration of wastewater treatment plant effluent. In this study, we characterized concentrations of pharmaceuticals, perfluorosurfactants, and other organic wastewater compounds (OWCs) in the unconfined sand and gravel aquifer of Cape Cod, Massachusetts, USA, where septic systems are prevalent. Raw water samples from 20 public drinking water supply wells on Cape Cod were tested for 92 OWCs, as well as surrogates of wastewater impact. Fifteen of 20 wells contained at least one OWC; the two most frequently-detected chemicals were sulfamethoxazole (antibiotic) and perfluorooctane sulfonate (perfluorosurfactant). Maximum concentrations of sulfamethoxazole (113 ng/L) and the anticonvulsant phenytoin (66 ng/L) matched or exceeded maximum reported concentrations in other U.S. public drinking water sources. The sum of pharmaceutical concentrations and the number of detected chemicals were both significantly correlated with nitrate, boron, and extent of unsewered residential and commercial development within 500 m, indicating that wastewater surrogates can be useful for identifying wells most likely to contain OWCs. Septic systems appear to be the primary source of OWCs in Cape Cod groundwater, although wastewater treatment plants and other sources were potential contributors to several wells. These results show that drinking water supplies in unconfined aquifers where septic systems are prevalent may be among the most vulnerable to OWCs. The presence of mixtures of OWCs in drinking water raises human health concerns; a full evaluation of potential risks is limited by a lack of health-based guidelines and toxicity assessments. PMID:24055660

  9. LARGE-SCALE NATURAL GRADIENT TRACER TEST IN SAND AND GRAVEL, CAPE CODE, MASSACHUSETTS 3. HYDRAULIC CONDUCTI- VITY AND CALCULATED MACRODISPERSIVITIES

    EPA Science Inventory

    Hydraulic conductivity (K) variability in a sand and gravel aquifer on Cape Cod, Massachusetts, was measured and subsequently used in stochastic transport theories to estimate macrodispersivities. Nearly 1500 K measurements were obtained by borehole flowmeter tests ...

  10. A search for aquifers of sand and gravel by electrical-resistivity methods in north-central New Castle County, Delaware

    USGS Publications Warehouse

    Spicer, H. Cecil; McCullough, Richard A.; Mack, Frederick K.

    1955-01-01

    A search for aquifers in an area immediately north of the Chesapeake and Delaware Canal in New Castle, Del., has been made by an electrical resistivity study.  The search located 32 sites that may be underlain by sand and gravel. The thicker deposits are significant with respect to the occurrence of ground water, and all of them are of interest as possible sources of sand and gravel for construction purposes, such as for highway construction.  The thickness of these deposits ranges from 4.4 feet to 77 feet, and the computed resistivity for these ranges from a low of 97,800 ohm-cms to a high of 423,800 ohm-cms.  The study located with certainty one buried channel filled with sand and gravel deposits and pointed out the possibility of others that may be aquifers.  The interpretations show that a large deposit of sand and gravel is present in the eastern part of the area investigated and it is tentatively assumed that this deposit is continuous and may yield large quantities of ground water.  Places where the deposit was found to be the thickest and of high resistivity are described.

  11. WATER QUALITY CHANGES IN HYPORHEIC FLOW PATHS BETWEEN A LARGE GRAVEL BED RIVER AND OFF-CHANNEL ALCOVES IN OREGON, USA

    EPA Science Inventory

    Changes in water quality that occur as water flows along hyporheic flow paths may have important effects on surface water quality and aquatic habitat, yet very few studies have examined these hyporheic processes along large gravel bed rivers. To determine water quality changes as...

  12. LARGE-SCALE NATURAL GRADIENT TRACER TEST IN SAND AND GRAVEL, CAPE COD, MASSACHUSETTS - 1. EXPERIMENTAL DESIGN AND OBSERVED TRACER MOVEMENT

    EPA Science Inventory

    A large-scale natural gradient tracer experiment was conducted on Cape Cod, Massachusetts, to examine the transport and dispersion of solutes in a sand and gravel aquifer. The nonreactive tracer, bromide, and the reactive tracers, lithium and molybdate, were injected as a pulse i...

  13. MULTISPECIES REACTIVE TRACER TEST IN A SAND AND GRAVEL AQUIFER, CAPE COD, MASSACHUSETTS: PART 1: EXPERIMENTAL DESIGN AND TRANSPORT OF BROMIDE AND NICKEL-EDTA TRACERS

    EPA Science Inventory

    In this report, we summarize a portion of the results of a large-scale tracer test conducted at the U. S. Geological Survey research site on Cape Cod, Massachusetts. The site is located on a large sand and gravel glacial outwash plain in an unconfined aquifer. In April 1993, ab...

  14. The Influence of a Subslab Gravel Layer and Open Area on Soil-Gas and Radon Entry into Two Experimental Basements

    SciTech Connect

    Robinson, Allen L.; Sextro, R.G.

    1995-03-01

    Measurements of steady-state soil-gas and {sup 222}Rn entry rates into two room-sized, experimental basement structures were made for a range of structure depressurizations (0-40 Pa) and open floor areas (0-165 x 10{sup -4} m{sup 2}). The structures are identical except that in one the floor slab lies directly on native soil whereas in the other the slab lies on a high-permeability gravel layer. The subslab gravel layer greatly enhances the soil-gas and radon entry rate into the structure. The radon entry rate into the structure with the subslab gravel layer is four times greater than the entry rate into the structure without the gravel layer with an open floor area of 165 x 10{sup -4}m{sup 2}; however the ratio increases to 30 for an open floor area of 5.0 x 10{sup -4} m{sup 2}. The relationship between open area and soil-gas entry rate is complex. It depends on both the amount and distribution of the open area as well as the permeability of the soil near the opening. The entry rate into the experimental structures is largely determined by the presence or absence of a subslab gravel layer. Therefore open area is a poor indicator of radon and soil-gas entry into the structures. The extension of the soil-gas pressure field created by structure depressurization is a good measure of the radon entry. The measured normalized radon entry rate into both structures has the same linear relationship with the average subslab pressure coupling regardless of open area or the presence or absence of a subslab gravel layer. The average subslab pressure coupling is an estimate of the extension of the soil-gas pressure field. A three-dimensional finite-difference model correctly predicts the effect of a subslab gravel layer and different open area configurations on radon and soil-gas entry rate; however, the model underpredicts the absolute entry rate into each structure by a factor of 1.5.

  15. The Influence of a Subslab Gravel Layer and Open Area on Soil-Gas and Radon Entry into Two Experimental Basements

    SciTech Connect

    Robinson, Arthur L.; Sextro, R.G.

    1994-09-01

    Measurements of steady-state soil-gas and {sup 222}Rn entry rates into two room-sized, experimental basement structures were made for a range of structure depressurizations (0-40 Pa) and open areas (0-165 x 10{sup -4} m{sup 2}). The structures are identical except that in one the floor slab lies directly on native soil whereas in the other the slab lies on a high permeability gravel layer. The subslab gravel layer greatly enhances the soil-gas and radon entry rate into the structure. The radon entry rate into the structure with the subslab gravel layer is four times greater than the entry rate into the structure without the gravel layer with an open area of 165 x 10{sup -4} m{sup 2}; the ratio increases to 30 for an open area of 5.0 x 10{sup -4} m{sup 2}. Although open area is a poor indicator of radon and soil-gas entry into the experimental structure, the extension of the soil-gas pressure field created by structure depressurization is a good measure of the radon entry rate into the experimental structures. The measured normalized radon entry rate into both structures has the same linear relationship with the average subslab pressure coupling regardless of open area. The average subslab pressure coupling is a measure of the extension of the soil-gas pressure field. A three-dimensional finite-difference model correctly predicts the effect of a subslab gravel layer, and different open area configurations on radon and soil-gas entry rate; however, the model underpredicts the absolute entry rates into both structures by a factor of 1.5.

  16. Coupling channel evolution monitoring and RFID tracking in a large, wandering, gravel-bed river: Insights into sediment routing on geomorphic continuity through a riffle-pool sequence

    NASA Astrophysics Data System (ADS)

    Chapuis, Margot; Dufour, Simon; Provansal, Mireille; Couvert, Bernard; de Linares, Matthieu

    2015-02-01

    Bedload transport and bedform mobility in large gravel-bed rivers are not easily monitored, especially during floods. Large reaches present difficulties in bed access during flows for flow measurements. Because of these logistical issues, the current knowledge about bedload transport processes and bedform mobility lacks field-based information, while this missing information would precisely match river management needs. The lack of information linking channel evolution and particle displacements is even more striking in wandering reaches. The Durance River is a large, wandering, gravel-bed river (catchment area: 14,280 km2; mean width: 240 m), located in the southern French Alps and highly impacted by flow diversion and gravel mining. In order to improve current understanding of the link between sediment transport processes and river bed morphodynamics, we set up a sediment particle survey in the channel using Radio Frequency Identification (RFID) tracking and topographic surveys (GPS RTK and scour chains) for a 4-year recurrence interval flood. By combining topographic changes before and after a flood, intraflood erosion/deposition patterns from scour chains, differential routing of tracer particles, and spatial distribution of bed shear stress through a complex reach, this paper aims to define the critical shear stress for significant sediment mobility in this setting. Gravel tracking highlights displacement patterns in agreement with bar downstream migration and transport of particles across the riffle within this single flood event. Because no velocity measurements were possible during flood, a TELEMAC three-dimensional model helped interpret particle displacements by estimating spatial distribution of shear stresses and flow directions at peak flow. Although RFID tracking in a large, wandering, gravel-bed river does have some technical limitations (burial, recovery process time-consuming), it provides useful information on sediment routing through a riffle

  17. Large wood budget assessment along a gravel bed river affected by volcanic eruption: the Rio Blanco study case (Chile).

    NASA Astrophysics Data System (ADS)

    Oss-Cazzador, Daniele; Iroume, Andres; Lenzi, Mario; Picco, Lorenzo

    2016-04-01

    Wood in riverine environments exerts different functions on ecological and geomorphic settings, influencing morphological processes, and increasing risks for sensitive structures. Large wood (LW) is defined as wood material, dead or alive, larger than 10 cm in diameter and 1 m in length. Natural hazards can strongly increase the presence of LW in waterways and flood events can transport it affecting the ecosystem and landscape. This study aims to increase the knowledge of wood budget, considering the effects of two subsequent slight flood events along a sub-reach of the Rio Blanco gravel bed river , in Chilean Patagonia, strongly affected by the eruption of Chaiten volcano in 2008. The volcanic eruption affected almost 3,5 km 2 of evergreen forest on the southern (left) bank, because of primary direct effects from pyroclastic density currents and lahar-floods that caused deposition up to 8 m of reworked tephra, alluvium, and wood on floodplains and terrace along the Rio Blanco. After the eruption, there was a considerable increase of LW into the main channel: into the bankfull channel, volume exceeds 100 m 3 /ha. Field surveys were carried out in January and March 2015, before and after two slight flood events (Recurrence Intervals lower than 1 year). The pre-event phase permitted to detect and analyze the presence of LW into the study area, along a 80 m-long reach of Rio Blanco (7500 m 2 . Every LW element was manually measured and described, a numbered metal tag was installed, and the position was recorded by GPS device. In January, there was a total amount of 113 m 3 /ha, 90% accumulated in LW jams (WJ) and 10% as single logs. The LW was characterized by mean dimensions of 3,36 m height, 0,25 m diameter and 0,26 m 3 volume, respectively. The WJ are characterized by wide range of dimension: volume varies from 0,28 m 3 to 672 m 3 , length from 1,20 m to 56 m, width from 0,40 m to 8,70 m and height from 0,20 m to 3 m, respectively. After the flood events, field

  18. Clay minerals and gravels of late Pleistocene interstadial coastal sediments above the current sea level, south coast of Korea

    NASA Astrophysics Data System (ADS)

    Yang, D. Y.; Kim, J. C.; Lim, J.; Yi, S.; Nahm, W. H.; Kim, J. Y.; Han, M.

    2015-12-01

    At nowadays, the severe greenhouse effect causes rapid sea level rise around the Korea Peninsula. Paleo-climate researches have been concentrating on hydrological activities during the mid-Holocene optimum and the last interglacial period to use the paleo-analogues data in predicting the future hydrological environments. The previous studies on the late Pleistocene interstadial coastal sediments have primarily been biased towards the terraces of the east coast in the Korean Peninsula. According to the results, the last interglacial marine terraces of the east coast were existed at 18 m in elevation. Uplift rate of them was presumed to be 0.1mm/year (Choi, 2006). Also, the stratigraphy of the Quaternary coastal deposits of the Yellow Sea has been suggested by Park et al. (1998) and Lim et al. (2003). In recent, Jang et al. (2014) reported the OSL dated Eemian marine deposit along the southwest coast of Korea. However, the age-equivalent outcrops of the south coast are not discovered yet. The first outcrops of the late Pleistocene interstadial coastal sediment above the present sea level were discovered at IJin-ri site of Haenam, south coast of Korea. It would be very useful for calculating the rates of Eemian sea level rise and uplift of south coast of Korea. 62 cubic samples were collected at 6 cm intervals from the section (4.8-8.83m in elevation). Four sedimentary units, from Unit 1 to 4 in ascending order, are distinguished based on sedimentary textures and grain size distribution as follows: Unit 1 (sand, 4.8 m-5.32 m in elevation), Unit 2 (silty clay, 5.32 m-6.8 m in elevation), Unit 3 (gravelly sand, 6.8m-7.8m in elevation) and, Unit 4(sandy gravel, 7.8m-8.83m in elevation). The sediments which included rounded or semi-rounded gravels are thought to be transported from marine. Also, the assemblages of clay minerals from the sections are similar to those of Yellow Sea. It shows the possibility that the sediments originated from marine during high sea level

  19. Relative contributions of sand and gravel bedload transport to acoustic Doppler bedload- velocity magnitudes in the Trinity River, California

    NASA Astrophysics Data System (ADS)

    Gaeuman, D.; Pittman, S.

    2007-12-01

    Apparent bedload velocities measured using the bottom-track feature of acoustic Doppler current profilers (ADCPs) have received attention over the past few years as potential surrogate technique for estimating bedload transport rates and for investigating bedload dynamics. This poster reports findings from perhaps the first use of ADCP bedload velocity measurements in an applied sediment monitoring program. Sediment transport data reported here were collected under the auspices of the Trinity River Restoration Program as part of an intensive sediment monitoring effort to assess the effects of the 2006 flow release in the Trinity River of Northern California. A 1200-kHz ADCP was deployed for a subset of bedload samples collected during the release to evaluate whether acoustic bedload velocities can be used to aid interpolation between less-frequent physical samples. Paired conventional bedload samples and acoustic bedload velocity samples supplemented by underwater video showed that the instrument used in this study is sensitive primarily to the motion of sand-sized particles at the bed, but comparatively insensitive to the motion of gravel- and cobble-sized particles. High bed velocities were measured at times and in locations where sand transport rates at the bed were high, as determined by both physical samples and video. Low bed velocities were measured where both the video and bedload samples indicated that little or no bedload was being transported, irrespective of the persistence of fast-moving sand particles in the near-bed water column. To the extent that suspended or saltating particles influence the bottom- track signal, they are near enough to the bed to be captured in the physical sampler. Thus, contamination of the bottom-track signal by suspended particles (commonly referred to as water bias) is not a significant problem with this instrument in streams with low to moderate suspended sediment concentrations. These results demonstrate that acoustic

  20. Geochemical heterogeneity in a sand and gravel aquifer: Effect of sediment mineralogy and particle size on the sorption of chlorobenzenes

    USGS Publications Warehouse

    Barber, L.B., II; Thurman, E.M.; Runnells, D.R.

    1992-01-01

    The effect of particle size, mineralogy and sediment organic carbon (SOC) on solution of tetrachlorobenzene and pentachlorobenzene was evaluated using batch-isotherm experiments on sediment particle-size and mineralogical fractions from a sand and gravel aquifer, Cape Cod, Massachusetts. Concentration of SOC and sorption of chlorobenzenes increase with decreasing particle size. For a given particle size, the magnetic fraction has a higher SOC content and sorption capacity than the bulk or non-magnetic fractions. Sorption appears to be controlled by the magnetic minerals, which comprise only 5-25% of the bulk sediment. Although SOC content of the bulk sediment is < 0.1%, the observed sorption of chlorobenzenes is consistent with a partition mechanism and is adequately predicted by models relating sorption to the octanol/water partition coefficient of the solute and SOC content. A conceptual model based on preferential association of dissolved organic matter with positively-charged mineral surfaces is proposed to describe micro-scale, intergranular variability in sorption properties of the aquifer sediments.The effect of particle size, mineralogy and sediment organic carbon (SOC) on sorption of tetrachlorobenzene and pentachlorobenzene was evaluated using batch-isotherm experiments on sediment particle-size and mineralogical fractions from a sand and gravel aquifer, Cape Cod, Massachusetts. Concentration of SOC and sorption of chlorobenzenes increase with decreasing particle size. For a given particle size, the magnetic fraction has a higher SOC content and sorption capacity than the bulk or non-magnetic fractions. Sorption appears to be controlled by the magnetic minerals, which comprise only 5-25% of the bulk sediment. Although SOC content of the bulk sediment is <0.1%, the observed sorption of chlorobenzenes is consistent with a partition mechanism and is adequately predicted by models relating sorption to the octanol/water partition coefficient of the solute and

  1. Channel morphodynamics and habitat recovery in a river reach affected by gravel-mining (River Ésera, Ebro basin)

    NASA Astrophysics Data System (ADS)

    Lopez-Tarazon, J. A.; Lobera, G.; Andrés-Doménech, I.; Martínez-Capel, F.; Muñoz-Mas, R.; Vallés, F.; Tena, A.; Vericat, D.; Batalla, R. J.

    2012-04-01

    Physical processes in rivers are the result of the interaction between flow regime and hydraulics, morphology, sedimentology and sediment transport. The frequency and magnitude of physical disturbance (i.e. bed stability) control habitat integrity and, consequently, ecological diversity of a particular fluvial system. Most rivers experience human-induced perturbations that alter such hydrosedimentary equilibrium, thus affecting the habitat of aquatic species. A dynamic balance may take long time to be newly attained. Within this context, gravel mining is well known to affect channel characteristics mostly at the local scale, but its effect may also propagate downstream and upstream. Sedimentary forms are modified during extraction and habitat features are reduced or even eliminated. Effects tend to be most acute in contrasted climatic environments, such as the Mediterranean areas, in which climatic and hydrological variability maximises effects of impacts and precludes short regeneration periods. Present research focuses on the evolution of a river reach, which has experienced an intense gravel extraction. The selected area is located in the River Ésera (Ebro basin), where interactions between morphodynamics and habitat recovery are examined. Emphasis is put on monitoring sedimentary, morphological and hydraulic variables to later compare pre (t0) and post (t1, t2... tn) extraction situations. Methodology for all time monitoring steps (i.e. ti) includes: i) characterization of grain size distribution at all of the different hydromorphological units within the reach; ii) description of channel morphology (together with changes before and after floods) by means of close-range aerial photographs, which are taken with a digital camera attached to a 1m3 helium balloon (i.e. BLIMP); and iii) determination of flow parameters from 2D hydraulic modelling that is based on detailed topographical data obtained from Leica® GNSS/GPS and robotic total station, and River

  2. Neogene transpressional foreland basin development on the north side of the central alaska range, usibelli group and nenana gravel, tanana basin

    USGS Publications Warehouse

    Ridgway, K.D.; Thoms, E.E.; Layer, P.W.; Lesh, M.E.; White, J.M.; Smith, S.V.

    2007-01-01

    Neogene strata of the Tanana basin provide a long-term record of a northwardpropagating, transpressional foreland-basin system related to regional shortening of the central Alaska Range and strike-slip displacement on the Denali fault system. These strata are ???2 km thick and have been deformed and exhumed in thrust faults that form the foothills on the north side of the Alaska Range. The lower part of the sedimentary package, the Usibelli Group, consists of 800 m of mainly Miocene strata that were deposited in fluvial, lacustrine, and peat bog environments of the foredeep depozone of the foreland-basin system. Compositional data from conglomerate and sandstone, as well as recycled Upper Cretaceous palynomorphs, indicate that the Miocene foreland-basin system was supplied increasing amounts of sediment from lithologies currently exposed in thrust sheets located south of the basin. The upper part of the sedimentary package, the Nenana Gravel, consists of 1200 m of mainly Pliocene strata that were deposited in alluvial-fan and braidplain environments in the wedge-top depozone of the foreland-basin system. Compositional data from conglomerate and sandstone, as well as 40Ar/39Ar dating of detrital feldspars in sandstone and from granitic clasts in conglomerate, indicate that lithologies exposed in the central Alaska Range provided most of the detritus to the Pliocene foreland-basin system. 40Ar/39Ar dates from detrital feldspar grains also show that two main suites of plutons contributed sediment to the Nenana Gravel. Detrital feldspars with an average age of 56 Ma are interpreted to have been derived from the McKinley sequence of plutons located south of the Denali fault. Detrital feldspars with an average age of 34 Ma are interpreted to have been derived from plutons located north of the Denali fault. Plutons located south of the Denali fault provided detritus for the lower part of the Nenana Gravel, whereas plutons located north of the Denali fault began to

  3. A functional collapse of persistent shell-gravel benthic ecosystem on the California shelf within the last century

    NASA Astrophysics Data System (ADS)

    Tomasovych, Adam; Kidwell, Susan M.

    2016-04-01

    Death assemblages sampled from the muddy seabed of the inner and middle mainland Southern California continental shelf frequently contain dead shells of epifaunal terebratulid brachiopod and large-bodied scallop species that have not been encountered alive during annual surveys of this area over the last four decades. Instead, live-collected shelly benthos is dominated by infaunal species, especially chemosynthetic and deposit-feeding bivalves. Postmortem age-frequency distributions based on 190 individuals of the brachiopod Laqueus show (1) a mode between 100 and 300 years, (2) the absence of shells younger than 100 years old, and (3) the continuous presence of shells older than 300 years, ranging up to six thousands of years old, implying the relatively continuous active production of shells by this brachiopod species over millennia. The localized occurrence of small living populations of this brachiopod and of the scallops Chlamys and Euvola under the reduced sedimentation conditions along the outermost edge of the mainland shelf, and their occurrence on the sandy shelves of the isolated, offshore Channel Islands less affected by natural and anthropogenic runoff, indicates that, up until the last century, the inner and middle mainland shelf had also been characterized by extensive areas of mud-free, shell-gravel habitat. The shift in community structure to the spatially pervasive, infauna-dominated muddy habitats encountered today implies a change to higher siltation and sediment loading due to increased land clearance within recent centuries.

  4. Negative correlation between porosity and hydraulic conductivity in sand-and-gravel aquifers at Cape Cod, Massachusetts, USA

    USGS Publications Warehouse

    Morin, R.H.

    2006-01-01

    Although it may be intuitive to think of the hydraulic conductivity K of unconsolidated, coarse-grained sediments as increasing monotonically with increasing porosity ??, studies have documented a negative correlation between these two parameters under certain grain-size distributions and packing arrangements. This is confirmed at two sites on Cape Cod, Massachusetts, USA, where groundwater investigations were conducted in sand-and-gravel aquifers specifically to examine the interdependency of several aquifer properties using measurements from four geophysical well logs. Along with K and ??, the electrical resistivity R0 and the natural gamma activity ?? of saturated deposits were determined as functions of depth. Qualitative examination of results from the first site implies a negative correlation between K and ?? that is substantiated by a rigorous multivariate analysis of log data collected from the second site. A principal components analysis describes an over-determined system of inversion equations, with approximately 92% of the cumulative proportion of the total variance being accounted for by only three of the four eigenvectors. A subsequent R-mode factor analysis projects directional trends among the four variables (K, ??, R0 and ??), and a negative correlation between K and ?? emerges as the primary result. ?? 2005 Elsevier B.V. All rights reserved.

  5. Batch experiments characterizing the reduction of Cr(VI) using suboxic material from a mildly reducing sand and gravel aquifer

    USGS Publications Warehouse

    Anderson, L.D.; Kent, D.B.; Davis, J.A.

    1994-01-01

    Batch experiments were conducted with sand collected from a shallow sand and gravel aquifer to identify the principal chemical reactions influencing the reduction of Cr(VI), so that field-observed Cr(VI) reduction could be described. The reduction appeared to be heterogeneous and occurred primarily on Fe(II)-bearing minerals. At only 1 wt %, the fine fraction (<64 ??m diameter) of the sediments dominated the amount of aqueous Cr(VI) reduction because of its greater reactivity and surface area. Although reduction of Cr(VI) increased with decreasing pH, small variations in the abundance of fine fraction among the replicate samples obscured pH trends in the batch experiments. Consistent results could only be obtained by separating the fine material from the sand and running parallel experiments on each fraction. As pH decreased (6.4 to 4.5), Cr(VI) reduction increased from 30 to 50 nmol/m2 for the sand fraction (64-1000 ??m) and from 130 to 200 nmol/m2 for the fine fraction. The amount of Cr(VI) reduced in both the sand-sized and fine material increased from 35 to 80 and from 130 to 1000 nmol/m2, respectively, for a 10-fold increase in Cr(VI)initial. A consistent description of the rate data was achieved by assuming that intraparticle diffusion limited the observed rate of reduction.

  6. Transport and recovery of bacteriophage PRD1 in a sand and gravel aquifer: Effect of sewage-derived organic matter

    USGS Publications Warehouse

    Pieper, A.P.; Ryan, J.N.; Harvey, R.W.; Amy, G.L.; Illangasekare, T.H.; Metge, D.W.

    1997-01-01

    To test the effects of sewage-derived organic matter on virus attachment, 32P-labeled bacteriophage PRD1, linear alkylbenzene sulfonates (LAS), and tracers were injected into sewage-contaminated (suboxic, elevated organic matter) and uncontaminated (oxic, low organic matter) zones of an iron oxide-coated quartz sand and gravel aquifer on Cape Cod, MA. In the uncontaminated zone, 83% of the PRD1 were attenuated over the first meter of transport by attachment to aquifer grains. In the contaminated zone, 42% of the PRD1 were attenuated over the first meter of transport. Sewage-derived organic matter contributed to the difference in PRD1 attenuation by blocking attachment sites in the contaminated zone. At greater distances down gradient (to a total transport distance of 3.6 m), a near-constant amount of PRD1 continued to break through, suggesting that aquifer grain heterogeneities allowed a small amount of reversible attachment. Injection of an LAS mixture (25 mg L-1), a common sewage constituent, remobilized 87% of the attached PRD1 in the contaminated zone, but only 2.2% in the uncontaminated zone. LAS adsorption promoted virus recovery in the contaminated zone by altering the PRD1-surface interactions; however, the amount of LAS adsorbed was not sufficient to promote release of the attached PRD1 in the uncontaminated zone.

  7. Utilizing Ground-based LiDAR (Terrestrial Laser Scanning) to estimate hydraulic roughness in gravel-bed rivers

    NASA Astrophysics Data System (ADS)

    Minear, J. T.; Wright, S. A.

    2012-12-01

    Roughness is one of the more difficult parameters to quantify in the field for hydraulic studies, partially because it occurs at a variety of scales (i.e. grain, unit and reach), and because individual roughness elements, such as trees, grass and sediment grains, are difficult to measure. Ground-based LiDAR (also known as Terrestrial Laser Scanning) is changing the collection of high-quality topographic datasets for a variety of scientific endeavors, including forestry, geomorphology and hydrology and can be used to quantify hydraulic roughness in the field. Using datasets collected from several rivers in California, we evaluate the use of ground-based LiDAR (also known as Terrestrial Laser Scanning) for estimating hydraulic roughness in gravel-bed rivers. From our initial measurements, in addition to topography, there are a number of useful parameters that can be collected quickly and efficiently with ground-based LiDAR, including some that are not explicitly considered by existing hydraulic equations.

  8. Use of Buried Sediment Traps to Estimate Deposition of Fine-Grained Sediment and Organic Contaminants in Salmon Spawning Gravels

    NASA Astrophysics Data System (ADS)

    Anderson, C.

    2005-05-01

    Deposition of fine-grained sediments into spawning gravels was estimated in the McKenzie River, OR, in conjunction with reservoir drawdown. Collapsed bags were buried at a depth of 40 cm during August 2003 and retrieved in July 2004. The deployment period included several mid-winter storms when sediment transport was high. Retrieval captured the column of bed sediment overlying the bags, including possible contaminants. Grain size distribution, percent and mass of fine material, chlorinated organic compounds, and organic carbon were measured in the retrieved sediment and pore waters. Deposition of fine materials was least in upstream reference areas, greatest in tributaries downstream of two different reservoirs, and intermediate downstream on the mainstem McKenzie River. Low-levels of organochlorine compounds were detected at two of the five sites, including below one reservoir where historical DDT spraying had occurred, and at the downstream mainstem location. The collapsed bag design, with Teflon lining, was an effective method to estimate time-integrated deposition of fine sediment and contaminants into a streambed.

  9. Chapter J: Issues and challenges in the application of geostatistics and spatial-data analysis to the characterization of sand-and-gravel resources

    USGS Publications Warehouse

    Hack, Daniel R.

    2005-01-01

    Sand-and-gravel (aggregate) resources are a critical component of the Nation's infrastructure, yet aggregate-mining technologies lag far behind those of metalliferous mining and other sectors. Deposit-evaluation and site-characterization methodologies are antiquated, and few serious studies of the potential applications of spatial-data analysis and geostatistics have been published. However, because of commodity usage and the necessary proximity of a mine to end use, aggregate-resource exploration and evaluation differ fundamentally from comparable activities for metalliferous ores. Acceptable practices, therefore, can reflect this cruder scale. The increasing use of computer technologies is colliding with the need for sand-and-gravel mines to modernize and improve their overall efficiency of exploration, mine planning, scheduling, automation, and other operations. The emergence of megaquarries in the 21st century will also be a contributing factor. Preliminary research into the practical applications of exploratory-data analysis (EDA) have been promising. For example, EDA was used to develop a linear-regression equation to forecast freeze-thaw durability from absorption values for Lower Paleozoic carbonate rocks mined for crushed aggregate from quarries in Oklahoma. Applications of EDA within a spatial context, a method of spatial-data analysis, have also been promising, as with the investigation of undeveloped sand-and-gravel resources in the sedimentary deposits of Pleistocene Lake Bonneville, Utah. Formal geostatistical investigations of sand-and-gravel deposits are quite rare, and the primary focus of those studies that have been completed is on the spatial characterization of deposit thickness and its subsequent effect on ore reserves. A thorough investigation of a gravel deposit in an active aggregate-mining area in central Essex, U.K., emphasized the problems inherent in the geostatistical characterization of particle-size-analysis data. Beyond such factors

  10. Study of extrabasinal-sourced rock clasts in Mesozoic and Cenozoic conglomerates and stream terrace gravels from the Colorado River Basin upstream from the Grand Canyon

    NASA Astrophysics Data System (ADS)

    Stoffer, P. W.; Dearaujo, J.; Li, A.; Adam, H.; White, L.

    2008-12-01

    Far-travelled durable, extrabasinal pebbles occur in Mesozoic and Tertiary conglomerate-bearing rock formations and in unconsolidated stream terrace gravels and mesa-capping gravel deposits of Late Tertiary and Quaternary age throughout the Colorado Plateau. Pebble collections were made from each of the major modern tributaries of the Colorado River for possible correlation of remnant gravel deposits remaining from the ancestral regional drainage system that existed prior to the formation of the Grand Canyon. Pebble collecting and sorting techniques were used to make representative collections with both representative and eye-catching lithologies that can be most useful for correlation. Pebbles found in the conglomerate and younger gravel deposits were evaluated to determine general sediment source areas based on unique lithologies, pebble-shape characteristics, and fossils. Chert pebbles derived from source areas in the Great Basin region during the Mesozoic are perhaps the most common, and many of these display evidence of tectonic fracturing during deep burial sometime during their geologic journey. Unique chert pebble lithologies correlate to specific rock units including chert-bearing horizons within the Triassic Shinarump Formation, the Jurassic Morrison and Navajo Formations, and the Cretaceous Mancos Shale. Quartzite, metaconglomerate, and granitic rocks derived from Precambrian rocks of the Rocky Mountain region are also common. Reworked rounded and flattened quartzite cobbles probably derived from shingled beaches along the western shoreline of the Late Cretaceous Western Interior Seaway are also common along the Green River drainage. Xenolith-bearing volcanic rocks, fossil wood, and shell fossils preserved in concretion matrix can be linked to other unique source areas and stratigraphic units across the region. By correlating the pebbles with their sources we gain insight into the erosional history of the Colorado Plateau and the evolution of the

  11. The occurrence of the colonial ascidian Didemnum sp. on Georges Bank gravel habitat: ecological observations and potential effects on groundfish and scallop fisheries

    USGS Publications Warehouse

    Valentine, P.C.; Collie, J.S.; Reid, R.N.; Asch, R.G.; Guida, V.G.; Blackwood, D.S.

    2007-01-01

    The colonial ascidian Didemnum sp. is present on the Georges Bank fishing grounds in a gravel habitat where the benthic invertebrate fauna has been monitored annually since 1994. The species was not noted before 2002 when large colonies were first observed; and by 2003 and 2004 it covered large areas of the seabed at some locations. The latest survey in 2005 documented the tunicate's presence in two gravel areas that total more than 67 nm2 (230 km2). The affected area is located on the Northern Edge of the bank in United States waters near the U.S./Canada boundary ( Fig. 1). This is the first documented offshore occurrence of a species that has colonized eastern U.S. coastal waters from New York to Maine during the past 15–20 years ( U.S. Geological Survey, 2006). Video imagery shows colonies coalescing to form large mats that cover more than 50% of the seabed along some video/photo transects. The affected area is an immobile pebble and cobble pavement that lies at water depths of 40 to 65 m where strong semidiurnal tidal currents reach speeds of 1 to 2 kt (50–100 cm/s). The water column is mixed year round, ensuring a constant supply of nutrients to the seabed. Annual temperatures range from 4 to 15 °C ( Mountain and Holzwarth, 1989). The gravel areas are bounded by sand ridges whose mobile surfaces are moved daily by the strong tidal currents. Studies commenced here in 1994 to characterize the gravel habitat and to document the effects of fishing disturbance on it ( Collie et al., 2005).

  12. Steep Gravel Bedload Rating Curves Obtained From Bedload Traps Shift Effective Discharge to Flows Much Higher Than "Bankfull"

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    Effective discharge (Qeff) is defined as the flow at which the product of flow frequency and bedload transport rates obtains its maximum. Qeff is often reported to correspond with bankfull flow (Qbf), where Qeff approximates the 1.5 year recurrence interval flow (Q1.5). Because it transports the majority of all bedload, Qeff is considered a design flow for stream restoration and flow management. This study investigates the relationship between Qeff and Q1.5 for gravel bedload in high elevation Rocky Mountain streams. Both the flow frequency distribution (FQ = a × Qbin-b) where Qbin is the flow class, and the bedload transport rating curve (QB = c × Qd) can be described by power functions. The product FQ × QB = (a × c × Q(-b + d)) is positive if d + -b >0, and negative if d + -b <0. FQ × QB can only attain a maximum (=Qeff) if either FQ or QB exhibit an inflection point. In snowmelt regimes, low flows prevail for much of the year, while high flows are limited to a few days, and extreme floods are rare. In log-log plotting scale, this distribution causes the longterm flow frequency function FQ to steepen in the vicinity of Q1.5. If the bedload rating curve exponent is small, e.g., = 3 as is typical of Helley-Smith bedload samples, d + -b shifts from >0 to <0, causing FQ × QB to peak, and Qeff to be around Q1.5. For measurements thought to be more representative of actual gravel transport obtained using bedload traps and similar devices, large rating curve exponents d of 6 - 16 are typical. In this case, d + -b remains >0, and FQ × QB reaches its maximum near the largest flow on record (Qeff,BT = Qmax). Expression of FQ by negative exponential functions FQ = k × e(Qbin×-m) smooths the product function FQ × QB that displays its maximum as a gentle hump rather than a sharp peak, but without drastically altering Qeff. However, a smooth function FQ × QB allows Qeff to react to small changes in rating curve exponents d. As d increases from <1 to >10, Qeff

  13. Thermal and hydrodynamic variability within a gravel bar of an Alpine stream and its link to hyporheic carbon cycling

    NASA Astrophysics Data System (ADS)

    Boodoo, Kyle; Schelker, Jakob; Fasching, Christina; Ulseth, Amber; Battin, Tom

    2015-04-01

    In-stream bodies of fluvial sediment such as gravel bars (GB), form an active interface between streamwater and the adjacent groundwater body. The hydrodynamic exchange, that is, the varying contributions of different water sources to this mixing zone, control the GB physical and biogeochemical conditions, including water temperature, as well as nutrient and carbon availability, likely impacting carbon turnover. We present high frequency data for hydraulic head and water temperature in addition to event based measurements of electric conductivity, nutrients and dissolved organic carbon (DOC) concentration and composition within a GB of an Alpine cold water stream (Oberer Seebach, Austria) for a range of different flow conditions. The highest vertical temperature differences and hydraulic head variability occurred at the head and shoulder - largest raised area perpendicular to surface water flow (downwelling) and tail (upwelling) of the gravel bar. At baseflow, high spatial variability of temperature (up to 4° C difference among sites within the same horizontal plane) and hydraulic head was observed within the GB. In contrast, floods resulted in markedly lower overall hyporheic zone temperatures (average 2° C difference among sites within the same horizontal plane) and spatial hydraulic head variability, compared to baseflow conditions. Similarly, the relative difference between surface water and GB nutrient and DOC concentrations and the overall spatial variability within the GB decreased with increasing surface water discharge. For example, at baseflow surface water average DOC and nitrate (NO3) concentrations were 1.40 mgL-1and 810 μgL-1respectively, and 1.97 mgL-1 and 779 μgL-1 respectively at intermediate flow. Meanwhile, DOC and NO3 concentrations in the GB ranged from 1.40 - 3.60 mgL-1 and 150 - 950 μgL-1respectively during baseflow and 1.48 -2.25 mgL-1 and 560 -840 μgL-1 respectively during moderate flows. Furthermore, DOC and NH4 concentrations

  14. The Devil is in the Details: Using X-Ray Computed Tomography to Develop Accurate 3D Grain Characteristics and Bed Structure Metrics for Gravel Bed Rivers

    NASA Astrophysics Data System (ADS)

    Voepel, H.; Hodge, R. A.; Leyland, J.; Sear, D. A.; Ahmed, S. I.

    2014-12-01

    Uncertainty for bedload estimates in gravel bed rivers is largely driven by our inability to characterize the arrangement and orientation of the sediment grains within the bed. The characteristics of the surface structure are produced by the water working of grains, which leads to structural differences in bedforms through differential patterns of grain sorting, packing, imbrication, mortaring and degree of bed armoring. Until recently the technical and logistical difficulties of characterizing the arrangement of sediment in 3D have prohibited a full understanding of how grains interact with stream flow and the feedback mechanisms that exist. Micro-focus X-ray CT has been used for non-destructive 3D imaging of grains within a series of intact sections of river bed taken from key morphological units (see Figure 1). Volume, center of mass, points of contact, protrusion and spatial orientation of individual surface grains are derived from these 3D images, which in turn, facilitates estimates of 3D static force properties at the grain-scale such as pivoting angles, buoyancy and gravity forces, and grain exposure. By aggregating representative samples of grain-scale properties of localized interacting sediment into overall metrics, we can compare and contrast bed stability at a macro-scale with respect to stream bed morphology. Understanding differences in bed stability through representative metrics derived at the grain-scale will ultimately lead to improved bedload estimates with reduced uncertainty and increased understanding of interactions between grain-scale properties on channel morphology. Figure 1. CT-Scans of a water worked gravel-filled pot. a. 3D rendered scan showing the outer mesh, and b. the same pot with the mesh removed. c. vertical change in porosity of the gravels sampled in 5mm volumes. Values are typical of those measured in the field and lab. d. 2-D slices through the gravels at 20% depth from surface (porosity = 0.35), and e. 75% depth from

  15. Septic systems as sources of organic wastewater compounds in domestic drinking water wells in a shallow sand and gravel aquifer.

    PubMed

    Schaider, Laurel A; Ackerman, Janet M; Rudel, Ruthann A

    2016-03-15

    Domestic drinking water wells serve 44 million people in the US and are common globally. They are often located in areas served by onsite wastewater treatment systems, including septic systems, which can be sources of biological and chemical pollutants to groundwater. In this study we tested 20 domestic drinking water wells in a sand and gravel aquifer on Cape Cod, Massachusetts, USA, for 117 organic wastewater compounds (OWCs) and for inorganic markers of septic system impact. We detected 27 OWCs, including 12 pharmaceuticals, five per- and polyfluoroalkyl substances (PFASs), four organophosphate flame retardants, and an artificial sweetener (acesulfame). Maximum concentrations of several PFASs and pharmaceuticals were relatively high compared to public drinking water supplies in the US. The number of detected OWCs and total concentrations of pharmaceuticals and of PFASs were positively correlated with nitrate, boron, and acesulfame and negatively correlated with well depth. These wells were all located in areas served exclusively by onsite wastewater treatment systems, which are likely the main source of the OWCs in these wells, although landfill leachate may also be a source. Our results suggest that current regulations to protect domestic wells from pathogens in septic system discharges do not prevent OWCs from reaching domestic wells, and that nitrate, a commonly measured drinking water contaminant, is a useful screening tool for OWCs in domestic wells. Nitrate concentrations of 1mg/L NO3-N, which are tenfold higher than local background and tenfold lower than the US federal drinking water standard, were associated with wastewater impacts from OWCs in this study. PMID:26822473

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

    NASA Astrophysics Data System (ADS)

    Lea, Devin M.

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

  17. Stream discharge events increase the reaction efficiency of the hyporheic zone of an in-stream gravel bar

    NASA Astrophysics Data System (ADS)

    Fleckenstein, J. H.; Trauth, N.; Schmidt, C.

    2015-12-01

    Streambed structures such as dunes, pool-riffles or bars enhance the exchange of stream water and solutes with the subsurface, the hyporheic zone. Prior studies have evaluated the factors which control hyporheic exchange and biogeochemical processes for steady state hydrological conditions using numerical models. However, the impact of natural discharge variability on water and solute exchange, creating hydraulically specific conditions for the reactions in the shallow streambed, has not been studied so far. In our study, we set up a transient flow and reactive transport model to elucidate the impact of single stream discharge events on water exchange, solute transport and reactions within the hyporheic zone of an in-stream gravel bar. The discharge events were varied by their duration and the maximum stream discharge. Temporally variable hydraulic heads were assigned as hydraulic head boundary conditions at the top of the reactive groundwater model MIN3P. A steady ambient groundwater flow field was introduced by lateral upstream and downstream hydraulic head boundaries, generating in combination with the stream water level, losing, neutral, or gaining stream conditions. Stream water borne dissolved oxygen, dissolved organic carbon and nitrate can infiltrate into the modelling domain across the top boundary and can react with each other by aerobic respiration and denitrification. Our results show that water and solute exchange through the hyporheic zone (only stream water that infiltrates into the subsurface and exfiltrates back to the stream) is highly dependent on the interplay between event characteristics and the ambient groundwater level. In scenarios where the stream discharge shifts the hydraulic system to strong and long-lasting losing conditions, hyporheic flow paths are longer and the extent of the hyporheic zone are deeper than under base flow conditions and small events where gaining conditions prevail. Consequently, stream discharge events may

  18. Stream discharge events increase the reactive efficiency of the hyporheic zone of an in-stream gravel bar

    NASA Astrophysics Data System (ADS)

    Trauth, Nico; Schmidt, Christian; Fleckenstein, Jan H.

    2016-04-01

    Streambed structures such as dunes, pool-riffles or bars enhance the exchange of stream water and solutes with the subsurface, the hyporheic zone. Prior studies have evaluated the factors which control hyporheic exchange and biogeochemical processes for steady state hydrological conditions using numerical models. However, the impact of natural discharge variability on water and solute exchange, creating hydraulically specific conditions for the reactions in the shallow streambed, has received less attention to date. In our study, we set up a transient flow and reactive transport model to elucidate the impact of single stream discharge events on water exchange, solute transport and reactions within the hyporheic zone of an in-stream gravel bar. The discharge events were varied by their duration and the maximum stream discharge. Temporally varying hydraulic heads were assigned as hydraulic head boundary conditions at the top of the reactive groundwater model MIN3P. A steady ambient groundwater flow field was introduced by lateral upstream and downstream hydraulic head boundaries, resulting in losing, neutral, or gaining conditions in the stream with respect to exchange with groundwater. Stream water borne dissolved oxygen, dissolved organic carbon and nitrate can infiltrate across the top of the modelling domain, where aerobic respiration and denitrification are simulated. Our results show that water and solute exchange through the hyporheic zone (only stream water that infiltrates into the subsurface and exfiltrates back to the stream) is highly dependent on the interplay between event characteristics and the ambient groundwater level. In scenarios where the stream discharge shifts the hydraulic system to strong and long-lasting losing conditions, hyporheic flow paths are longer and the extent of the hyporheic zone deeper than under base flow conditions and small hydrologic events where gaining conditions prevail. Consequently, stream discharge events may

  19. Three-dimensional steady-state simulation of flow in the sand-and-gravel aquifer, southern Escambia County, Florida

    USGS Publications Warehouse

    Trapp, Henry; Geiger, L.H.

    1986-01-01

    The sand-and-gravel aquifer is the only freshwater aquifer in southern Escambia County, Florida and is the source of public water supply for the area, including the City of Pensacola. The aquifer was simulated by a two-layer, digital model to provide hydrologic information for water resource planning. The lower layer represents the main-producing zone; the upper layer represents all of the aquifer above the main-producing zone including an unconfined zone and discontinuous perched, confined , and confining zones. The model was designed for steady-state simulation and predicts the response of the aquifer (changes in water levels) to groundwater pumping where steady-state conditions have been reached. Input to the model includes matrices representing constant-head nodes, starting head, transmissivity of layer 1, leakance between layers 1 and 2, lateral hydraulic conductivity of layer 2, and altitude of the base layer 2. The sources of water to the model are from recharge by infiltrated precipitation (estimated from base runoff), inflow across boundaries, and induced recharge from river leakance in periods of prolonged groundwater pumping. Model output includes final head and drawdown for each layer and total values for discharge and recharge in the model area. The model was calibrated for 1972 pumping and tested by simulating pumpages during 1939-40, 1958, and 1977. Sensitivity analyses showed water levels in both layers were most sensitive to changes in the recharge matrix and least sensitive to river leakage. Suggestions for further development of the model include subdivision and expansion of the grid, assignment of storage coefficients for transient simulations, more intensive study of the stream-aquifer relations, and consideration of the effects of infiltration basins on recharge. (Author 's abstract)

  20. [Effects of nitrogen management on yield, quality, nitrogen accumulation and its transportation of watermelon in gravel-mulched field].

    PubMed

    Ma, Zhong-ming; Du, Shao-ping; Xue, Liang

    2015-11-01

    The effects of nitrogen management on yield, quality, nitrogen and dry matter accumulation and transportation of watermelon in sand field were studied based on a field experiment. The results showed that too low or too high basal nitrogen fertilzation was unfavorable to seedling growth of watermelon in sand field, and no nitrogen application at vine extension or fruiting stages limited the formation of 'source' or 'sink'. At the same nitrogen rate, compared with the traditional T1 treatment (30% basal N fertilizer + 70% N fertilizer in vine extension), the nitrogen and dry matter accumulation of vegetative organs of T4 treatment (30% basal N fertilizer + 30% N fertilizer in vine extension + 40% N fertilizer in fruiting) and T6 treatment (100% basal N fertilizer + NAM) were reduced significantly, but the nitrogen and dry matter accumulation of fruit were increased significantly in the flushing period. The nitrogen transportation ratio and nitrogen contribution ratio of T4 were 33.6% and 12.0%, respectively. Compared to T1, the nitrogen harvest index, nitrogen fertilizer partial factor productivity and nitrogen fertilizer recovery efficiency of T4 and T6 treatments increased by 14.1% and 12.7%, 11.6% and 12.5%, 5.3% and 8.7%, respectively, and yield of watermelon increased by 11.6% and 12.5%, the soluble sugar, effective acid, the ratio of sugar and acid, Vc content increased by 16.5% and 11.7%, 4.5% and 2.8%, 19.4% and 13.4%, 35.6% and 19.0%, respectively. Therefore, T4 and T6 treatments were the optimal nitrogen fertilizer management mode which could not only achieve high yield and quality but also obtain high nitrogen fertilizer use efficiency in sand field. T6 treatment was the best nitrogen fertilizer management mode considering reduction of fertilizing labor intensity and extending service time of gravel-mulched field. PMID:26915190

  1. Effect of geometrical configuration of sediment replenishment on the development of bed form patterns in a gravel bed channel

    NASA Astrophysics Data System (ADS)

    Battisacco, Elena; Franca, Mário J.; Schleiss, Anton J.

    2016-04-01

    Dams interrupt the longitudinal continuity of river reaches since they store water and trap sediment in the upstream reservoir. By the interruption of the sediment continuum, the transport capacity of downstream stretch exceeds the sediment supply, thus the flow becomes "hungry". Sediment replenishment is an increasingly used method for restoring the continuity in rivers and for re-establishing the sediment regime of such disturbed river reaches. This research evaluates the effect of different geometrical configurations of sediment replenishment on the evolution of the bed morphology by systematic laboratory experiments. A typical straight armoured gravel reach is reproduced in a laboratory flume in terms of slope, grain size and cross section. The total amount of replenished sediment is placed in four identical volumes on both channel banks, forming six different geometrical configurations. Both alternated and parallel combinations are studied. Preliminary studies demonstrate that a complete submergence condition of the replenishment deposits is most adequate for obtaining a complete erosion and a high persistence of the replenished material in the channel. The response of the channel bed morphology to replenishment is documented by camera and laser scanners installed on a moveable carriage. The parallel configurations create an initially strong narrowing of the channel section. The transport capacity is thus higher and most of the replenished sediments exit the channel. The parallel configurations result in a more spread distribution of grains but with no clear morphological pattern. Clear bed form patterns can be observed when applying alternated configurations. Furthermore, the wavelength of depositions correspond to the replenishment deposit length. These morphological forms can be assumed as mounds. In order to enhance channel bed morphology on an armoured bed by sediment replenishment, alternated deposit configurations are more favourable and effective. The

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  3. Comparisons of Derived Metrics from Computed Tomography (CT) Scanned Images of Fluvial Sediment from Gravel-Bed Flume Experiments

    NASA Astrophysics Data System (ADS)

    Voepel, Hal; Ahmed, Sharif; Hodge, Rebecca; Leyland, Julian; Sear, David

    2016-04-01

    Uncertainty in bedload estimates for gravel bed rivers is largely driven by our inability to characterize arrangement, orientation and resultant forces of fluvial sediment in river beds. Water working of grains leads to structural differences between areas of the bed through particle sorting, packing, imbrication, mortaring and degree of bed armoring. In this study, non-destructive, micro-focus X-ray computed tomography (CT) imaging in 3D is used to visualize, quantify and assess the internal geometry of sections of a flume bed that have been extracted keeping their fabric intact. Flume experiments were conducted at 1:1 scaling of our prototype river. From the volume, center of mass, points of contact, and protrusion of individual grains derived from 3D scan data we estimate 3D static force properties at the grain-scale such as pivoting angles, buoyancy and gravity forces, and local grain exposure. Here metrics are derived for images from two flume experiments: one with a bed of coarse grains (>4mm) and the other where sand and clay were incorporated into the coarse flume bed. In addition to deriving force networks, comparison of metrics such as critical shear stress, pivot angles, grain distributions, principle axis orientation, and pore space over depth are made. This is the first time bed stability has been studied in 3D using CT scanned images of sediment from the bed surface to depths well into the subsurface. The derived metrics, inter-granular relationships and characterization of bed structures will lead to improved bedload estimates with reduced uncertainty, as well as improved understanding of relationships between sediment structure, grain size distribution and channel topography.

  4. Determination of bacterial and viral transport parameters in a gravel aquifer assuming linear kinetic sorption and desorption

    NASA Astrophysics Data System (ADS)

    Mallén, G.; Maloszewski, P.; Flynn, R.; Rossi, P.; Engel, M.; Seiler, K.-P.

    2005-05-01

    The bacteria Escherichia coli and Pseudomonas putida, and the bacteriophage virus H40/1 are examined both for their transport behaviour relative to inert solute tracers and for their modelability under natural flow conditions in a gravel aquifer. The microbes are attenuated in the following sequence: H40/1≥ P. putida≫ E. coli. The latter is desorbed almost completely within a few days. Breakthrough and recovery curves of the simultaneously injected non-reactive tracers are simulated with the 2D and 1D dispersion equation, in order to ascertain longitudinal dispersivity ( αL) and mean flow time ( T0). Mathematical modelling is difficult due to the aquifer heterogeneity, which results in preferential flow paths between injection and observation wells. Therefore, any attempt of fitting the dispersion model (DM) to the entire inert-tracer breakthrough curve (BTC) fails. Adequate fitting of the model to measured data only succeeds using a DM consisting of a superposition of several BTCs, each representing another set of flow paths. This gives rise to a multimodal, rather than a Gaussian groundwater velocity distribution. Only hydraulic parameters derived from the fastest partial curve, which is fitted to the rising part of the Uranine BTC, are suitable to model microbial breakthroughs. The hydraulic parameters found using 2D and 1D models were nearly identical. Their values were put into an analytical solution of 1D advective-dispersive transport combined with two-site reaction model introduced by Cameron and Klute [Cameron, D.R., Klute, A., 1977. Convective-dispersive solute transport with a combined equilibrium and kinetic adsorption model. Water Resour. Res. 13, 183-189], in order to identify reactive transport parameters (sorption/desorption) and attenuation mechanisms for the microbes migration. This shows that the microbes are almost entirely transported through preferential flow paths, which are represented by the first partial curve. Inert tracers, however

  5. Crude oil in a shallow sand and gravel aquifer-III. Biogeochemical reactions and mass balance modeling in anoxic groundwater

    USGS Publications Warehouse

    Baedecker, M.J.; Cozzarelli, I.M.; Eganhouse, R.P.; Siegel, D.I.; Bennett, P.C.

    1993-01-01

    Crude oil floating on the water table in a sand and gravel aquifer provides a constant source of hydrocarbons to the groundwater at a site near Bemidji, Minnesota. The degradation of hydrocarbons affects the concentrations of oxidized and reduced aqueous species in the anoxic part of the contaminant plume that developed downgradient from the oil body. The concentrations of Fe2+, Mn2+ and CH4, Eh measurements, and the ??13C ratios of the total inorganic C indicate that the plume became more reducing ver a 5-a period. However, the size of the contaminant plume remained stable during this time. Field data coupled with laboratory microcosm experiments indicate that benzene and the alkylbenzenes are degraded in an anoxic environment. In anaerobic microcosm experiments conducted under field conditions, almost complete degradation (98%) was observed for benzene in 125 d and for toluene in 45 d. Concentrations of aqueous Fe2+ and Mn2+ increased in these experiments, indicating that the primary reactions were hydrocarbon degradation coupled with Fe and Mn reduction. Mass transfer calculations on a 40-m flowpath in the anoxic zone, downgradient from the oil body, indicated that the primary reactions in the anoxic zone are oxidation of organic compounds, precipitation of siderite and a ferroan calcite, dissolution of iron oxide and outgassing of CH4 and CO2. The major difference in the two models presented is the ratio of CO2 and CH4 that outgasses. Both models indicate quantitatively that large amounts of Fe are dissolved and reprecipitated as ferrous iron in the anoxic zone of the contaminant plume. ?? 1993.

  6. Hydraulic and geomorphic processes in an overbank flood along a gravel-bed, meandering river: implications for chute formation

    NASA Astrophysics Data System (ADS)

    Harrison, L.; Dunne, T.; Fisher, G. B.

    2014-12-01

    Hydraulic interactions between rivers and floodplains produce off-channel chutes, whose presence can increase the ecological diversity of the valley floor. Detailed studies of the hydrologic exchanges between channels and floodplains are usually conducted in laboratory facilities, and studies documenting chute development are generally limited to qualitative observations. In this study, we use a reconstructed, gravel-bedded, meandering river as a laboratory for studying these mechanisms at field scale. Using an integrated field and modeling approach, we quantified the flow exchanges between the river channel and its floodplain during an overbank flood, and identified locations where flow had the capacity to erode floodplain chutes. Hydraulic measurements and modeling indicated high rates of flow exchange between the channel and floodplain, with flow rapidly decelerating as water was decanted from the channel onto the floodplain due to the frictional drag provided by substrate and riparian vegetation. Peak shear stresses were greatest downstream of the maxima in bend curvature, along the concave bank, where terrestrial LiDAR scans indicate initial floodplain chute formation. A second chute has developed across the convex bank of a meander bend, in a location where sediment accretion, point bar development and plant colonization have created divergent flow paths between the main channel and floodplain. In both cases, the off-channel chutes are evolving slowly during infrequent floods due to the coarse nature of the floodplain, though rapid chute formation would be more likely in finer-grained floodplains. The controls on chute formation at these locations include the river curvature, cross-stream position of the high velocity core, erodibility of the floodplain sediment, and the density of riparian vegetation.

  7. A mechanistic model linking insect (Hydropsychidae) silk nets to incipient sediment motion in gravel-bedded streams

    NASA Astrophysics Data System (ADS)

    Albertson, Lindsey K.; Sklar, Leonard S.; Pontau, Patricia; Dow, Michelle; Cardinale, Bradley J.

    2014-09-01

    Plants and animals affect stream morphodynamics across a range of scales, yet including biological traits of organisms in geomorphic process models remains a fundamental challenge. For example, laboratory experiments have shown that silk nets built by caddisfly larvae (Trichoptera: Hydropsychidae) can increase the shear stress required to initiate bed motion by more than a factor of 2. The contributions of specific biological traits are not well understood, however. Here we develop a theoretical model for the effects of insect nets on the threshold of sediment motion, τ*crit, that accounts for the mechanical properties, geometry, and vertical distribution of insect silk, as well as interactions between insect species. To parameterize the model, we measure the tensile strength, diameter, and number of silk threads in nets built by two common species of caddisfly, Arctopsyche californica and Ceratopsyche oslari. We compare model predictions with new measurements of τ*crit in experiments where we varied grain size and caddisfly species composition. The model is consistent with experimental results for single species, which show that the increase in τ*crit above the abiotic control peaks at 40-70% for 10-22 mm sediments and declines with increasing grain size. For the polyculture experiments, however, the model underpredicts the measured increase in τ*crit when two caddisfly species are present in sediments of larger grain sizes. Overall, the model helps explain why the presence of caddisfly silk can substantially increase the forces needed to initiate sediment motion in gravel-bedded streams and also illustrates the challenge of parameterizing the behavior of multiple interacting species in a physical model.

  8. Quantifying the co-evolution of morphology, hydraulics and spawning habitat in a recently restored gravel-bed river

    NASA Astrophysics Data System (ADS)

    Harrison, L. R.; Legleiter, C. J.; Wydzga, A. M.; Dunne, T.

    2008-12-01

    An emergent paradigm within restoration science is that restoration of natural physical processes is the best way to restore habitat for native organisms in degraded rivers. This concept, which underpins many restoration projects, is based on the notion that the establishment of an actively migrating, alluvial river channel-floodplain system will provide a number of desired ecological functions, each related to specific physical processes that occur at the habitat-scale. Here we quantify the rates of morphologic change, channel migration and the development of high-quality habitat, using a recently restored gravel-bed reach of the Merced River, California, USA. DEM-derived differences in bed elevation indicate that sediment storage accelerated processes of bar-building, pool scour, and bank erosion, leading to more asymmetric cross- sectional geometry. The volume of sediment stored on developing point bars was correlated with the migration distance of the outer bank, whereas in bends that have not accumulated sediment there has been little erosion, suggesting that channel migration was influenced by sediment supply as well as by channel curvature. The documented channel changes have had marked results on flow hydraulics, leading to decreased velocities over riffles and increased velocities in pools during low flow spawning conditions. Habitat modeling indicates that the quality of Chinook salmon (Oncorhynchus tshawytscha) spawning habitat has improved following the initial channel construction. These changes in morphology, hydraulics and habitat availability occurred primarily during two sustained periods of overbank flow. Collectively, these results highlight the importance of overbank flows and a sediment supply sufficient for bar growth in meander migration and creating channel complexity and high-quality habitat.

  9. Comparison of hydraulic conductivities for a sand and gravel aquifer in southeastern Massachusetts, estimated by three methods

    USGS Publications Warehouse

    Warren, L.P.; Church, P.E.; Turtora, Michael

    1996-01-01

    Hydraulic conductivities of a sand and gravel aquifer were estimated by three methods: constant- head multiport-permeameter tests, grain-size analyses (with the Hazen approximation method), and slug tests. Sediment cores from 45 boreholes were undivided or divided into two or three vertical sections to estimate hydraulic conductivity based on permeameter tests and grain-size analyses. The cores were collected from depth intervals in the screened zone of the aquifer in each observation well. Slug tests were performed on 29 observation wells installed in the boreholes. Hydraulic conductivities of 35 sediment cores estimated by use of permeameter tests ranged from 0.9 to 86 meters per day, with a mean of 22.8 meters per day. Hydraulic conductivities of 45 sediment cores estimated by use of grain-size analyses ranged from 0.5 to 206 meters per day, with a mean of 40.7 meters per day. Hydraulic conductivities of aquifer material at 29 observation wells estimated by use of slug tests ranged from 0.6 to 79 meters per day, with a mean of 32.9 meters per day. The repeatability of estimated hydraulic conductivities were estimated to be within 30 percent for the permeameter method, 12 percent for the grain-size method, and 9.5 percent for the slug test method. Statistical tests determined that the medians of estimates resulting from the slug tests and grain-size analyses were not significantly different but were significantly higher than the median of estimates resulting from the permeameter tests. Because the permeameter test is the only method considered which estimates vertical hydraulic conductivity, the difference in estimates may be attributed to vertical or horizontal anisotropy. The difference in the average hydraulic conductivities estimated by use of each method was less than 55 percent when compared to the estimated hydraulic conductivity determined from an aquifer test conducted near the study area.

  10. Polar gravel beach-ridge systems as archive of climate variations (South Shetland Islands / Western Antarctic Peninsula)

    NASA Astrophysics Data System (ADS)

    Lindhorst, Sebastian; Schutter, Ilona; Betzler, Christian

    2014-05-01

    The architecture of polar gravel beach-ridge systems is presented and their potential as archive of past wave-climate conditions is evaluated. Raised beaches are common on paraglacial coasts which experienced a net uplift during the Holocene as the result of postglacial isostatic rebound. Ground-penetrating radar data obtained along the coasts of Potter Peninsula (King George Island) show that beach ridges unconformably overlie seaward-dipping strata of the strand plain. Whereas strand-plain progradation is the result of swash sedimentation at the beach face under enduring calm conditions, ridge construction reflects enhanced wave action at the beach as the result of increased storminess or reduced nearshore sea ice. The number of individual ridges which are preserved from a given time interval varies along the coast depending on the morphodynamic setting: Sheltered coasts are characterized by numerous small ridges, whereas fewer but larger ridges develop on exposed beaches. The sedimentary architecture of individual beach ridges is interpreted to reflect maximum wave-runup height during the time of ridge construction. Ridges at sheltered parts of the coast exhibit either seaward-dipping beds, interpreted to result from swash deposition, or an aggradational stacking pattern being the result of wave overtopping. At exposed beaches, larger ridges develop composed of seaward- as well as landward-dipping beds. Radiocarbon data indicate that the frequency of ridge building ranges from decades in low-energy settings to more than 1500 years under high-energy conditions. In the study area, beach ridges group into four distinct levels: up to 4 m, 5.5 m, 7.5 m, and 10 m above the present day storm beach. Hence, these levels are interpreted to reflect periods of increased wave activity in the area of the South Shetland Islands at about 4.3, 3.1, 1.9, and 0.35 ka cal BP.

  11. Flume Experiments on the Influence of Salmon Spawning Density on Grain Stability and Bedload Transport in Gravel-bed Streams

    NASA Astrophysics Data System (ADS)

    Buxton, T. H.

    2015-12-01

    Salmon spawning in streams involves the female salmon digging a pit in the bed where she deposits eggs for fertilization before covering them with gravel excavated from the next pit upstream. Sequences of pit excavation and filling winnow fines, loosen sediment, and move bed material into a tailspill mound resembling the shape of a dune. Research suggests salmonid nests (redds) destabilize streambeds by reducing friction between loosened grains and converging flow that elevates shear stress on redd topography. However, bed stability may be enhanced by form drag from redds in clusters that lower shear stress on the granular bed, but this effect will vary with the proportion of the bed surface that is occupied by redds (P). I used simulated redds and water-worked ("unspawned") beds in a laboratory flume to evaluate these competing influences on grain stability and bedload transport rates with P=0.12, 0.34, and 0.41. Results indicate that competence (largest-grain) and reference transport rate estimates of critical conditions for particle entrainment inversely relate to P. Bedload transport increased as exponential functions of P and excess boundary shear stress. Therefore, redd form drag did not overcome the destabilizing effects of spawning. Instead, grain mobility and bedload transport increased with P because larger areas of the bed were composed of relatively loose, unstable grains and redd topography that experienced elevated shear stress. Consequently, the presence of redds in fish-bearing streams likely reduces the effects of sedimentation from landscape disturbance on stream habitats that salmon use for reproduction.

  12. Change in bedload transport frequency with climate warming in gravel-bed streams of the Oregon Cascades

    NASA Astrophysics Data System (ADS)

    Hempel, L. A.; Grant, G.; Lewis, S.; Safeeq, M.

    2014-12-01

    Previous modeling studies have predicted that high flows in the Oregon Cascades will become larger and shift towards earlier in the winter season with climate warming. The impact of those changes on bedload transport frequency and channel morphology remains unknown, however. We examined changes in the timing and magnitude of bedload transport under modeled flow scenarios to identify which rivers draining the Cascades with different hydrologic regimes are most vulnerable to increased frequency of bedload transport. Such increases in the frequency or magnitude of gravel entrainment might lead to disturbance of fragile salmon or bull trout habitat. We calculated bedload transport rates using field measurements of surface sediment size, channel geometry, and channel slope along 14 reaches that included streams with a range of drainage areas and flow regimes (i.e., spring-fed and surface-runoff dominated). Our findings suggest that both spring-fed and surface-runoff streams are vulnerable to predicted changes in the flow regime, but in different ways. Spring-fed streams, characterized by relatively uniform discharge, will likely experience changes in both the timing and magnitude of transport. Spring-fed streams are poised just above the critical transport threshold for a large portion of the year, therefore small changes in the highest flows may lead to marked changes in transport rates. Transport events in surface-runoff streams, which are already characterized by flashy flows, will likely become larger and more frequent. Changes in the frequency and timing of bedload transport in both spring-fed and surface runoff streams will impact bed stability and texture and should be considered for managing these watersheds in the future.

  13. River terrace sand and gravel deposit reserve estimation using three-dimensional electrical resistivity tomography for bedrock surface detection

    NASA Astrophysics Data System (ADS)

    Chambers, J. E.; Wilkinson, P. B.; Penn, S.; Meldrum, P. I.; Kuras, O.; Loke, M. H.; Gunn, D. A.

    2013-06-01

    We describe the application of 3D electrical resistivity tomography (ERT) to the characterisation and reserve estimation of an economic fluvial sand and gravel deposit. Due to the smoothness constraints used to regularise the inversion, it can be difficult to accurately determine the geometry of sharp interfaces. We have therefore considered two approaches to interface detection that we have applied to the 3D ERT results in an attempt to provide an accurate and objective assessment of the bedrock surface elevation. The first is a gradient-based approach, in which the steepest gradient of the vertical resistivity profile is assumed to correspond to the elevation of the mineral/bedrock interface. The second method uses an intrusive sample point to identify the interface resistivity at a location within the model, from which an iso-resistivity surface is identified that is assumed to define the interface. Validation of these methods has been achieved through direct comparison with observed bedrock surface elevations that were measured using real-time-kinematic GPS subsequent to the 3D ERT survey when quarrying exposed the bedrock surface. The gradient-based edge detector severely underestimated the depth to bedrock in this case, whereas the interface resistivity method produced bedrock surface elevations that were in close agreement with the GPS-derived surface. The failure of the gradient-based method is attributed to insufficient model sensitivity in the region of the bedrock surface, whereas the success of the interface resistivity method is a consequence of the homogeneity of the mineral and bedrock, resulting in a consistent interface resistivity. These results highlight the need for some intrusive data for model validation and for edge detection approaches to be chosen on the basis of local geological conditions.

  14. Infiltration and solute transport experiments in unsaturated sand and gravel, Cape Cod, Massachusetts: Experimental design and overview of results

    USGS Publications Warehouse

    Rudolph, D.L.; Kachanoski, R.G.; Celia, M.A.; LeBlanc, D.R.; Stevens, J.H.

    1996-01-01

    A series of infiltration and tracer experiments was conducted in unsaturated sand and gravel deposits on Cape Cod, Massachusetts. A network of 112 porous cup lysimeters and 168 time domain reflectometry (TDR) probes was deployed at depths from 0.25 to 2.0 m below ground surface along the centerline of a 2-m by 10-m test plot. The test plot was irrigated at rates ranging from 7.9 to 37.0 cm h-1 through a sprinkler system. Transient and steady state water content distributions were monitored with the TDR probes and spatial properties of water content distributions were determined from the TDR data. The spatial variance of the water content tended to increase as the average water content increased. In addition, estimated horizontal correlation length scales for water content were significantly smaller than those estimated by previous investigators for saturated hydraulic conductivity. Under steady state flow conditions at each irrigation rate, a sodium chloride solution was released as a tracer at ground surface and tracked with both the lysimeter and TDR networks. Transect-averaged breakthrough curves at each monitoring depth were constructed both from solute concentrations measured in the water samples and flux concentrations inferred from the TDR measurements. Transport properties, including apparent solute velocities, dispersion coefficients, and total mass balances, were determined independently from both sets of breakthrough curves. The dispersion coefficients tended to increase with depth, reaching a constant value with the lysimeter data and appearing to increase continually with the TDR data. The variations with depth of the solute transport parameters, along with observations of water and solute mass balance and spatial distributions of water content, provide evidence of significant three-dimensional flow during the irrigation experiments. The TDR methods are shown to efficiently provide dense spatial and temporal data sets for both flow and solute transport

  15. The Formation and Growth of Gravel Bars in Response to Increased Sediment Supply Following the Marmot Dam Removal

    NASA Astrophysics Data System (ADS)

    Podolak, C.; Wilcock, P.

    2009-12-01

    What makes some bars grow downstream, others grow upstream, while still others primarily grow in height with a nearly constant planform? The October 2007 removal of the Marmot Dam from the Sandy River, OR, and the subsequent liberation of nearly 750,000 cubic meters of sand and gravel served as an experimental setting to observe these various trajectories of bar growth. In the 2 kilometer reach immediately below the former dam site nearly 350,000 cubic meters were deposited during the first year following the removal. The sediment deposited downstream such that there exists a spatial as well as time variation in the amount of deposition seen by the downstream bars, providing an opportunity to measure different responses to various sediment supplies. This deposit both created bars where there were none the previous year, and increased the size of pre-existing bars. The formation and growth of the bars were analyzed using LIDAR, ground surveys, ground-level photographs, and aerial photography. Throughout the two year study period, new bars formed in an alternating lateral-bar sequence; a pre-existing point bar migrated downstream from the apex of a bend, and subsequently reset to the apex; and small riffle zones containing large (greater than 1 meter) boulders formed the skeleton for mid-channel bars which filled in and elongated upstream. The observations can be generalized by characterizing the pre-removal topography with a suite of topographic measures and observing relationships between the pre-removal measures, the post-removal measures, and the increased sediment supply. Newly formed bars in the portion of the reach with the highest rate of deposition had the greatest change in relief (measured from the thalweg to the top of the bar) while growth of the pre-existing bars was characterized by greater changes in length than in height or width. This study's observation of a small number of bars over a two-year period provides a base to which further observations

  16. Impacts of Bank Protection Measures on the Morphological Response of an Upland Gravel-Bed River in the UK

    NASA Astrophysics Data System (ADS)

    Waterhouse, E. K.; Lane, S. N.; Ferguson, R. I.

    2008-12-01

    A combined field based and modelling approach is used to explore the current and future impacts of river management along a 6 km reach of sinuous upland gravel-bed river. The Upper River Wharfe in the UK Yorkshire Dales, has been subjected to a range of river management schemes in response to concerns over unwanted bank erosion and an increase in flood risk; notably bank protection since the 1980's. Field monitoring, including a 6-year high resolution cross-sectional resurveying program, bank erosion study and estimated bedload transport rates from sediment impact sensors, are used to characterise vertical and lateral channel change in the river and compare protected and unprotected reaches. With the channel laterally confined in many places, sediment accumulates in the channel unable to be stored in the floodplain through the natural channel migration process. This sediment builds up, reduces the channel's capacity to hold flow and flood risk increases. Field results demonstrate that rates of accumulation in the Wharfe are having a large impact on flood-risk and are attributed to the bank restrictions. The field data are also applied and used to calibrate a quasi-2D model of channel adjustment for the reach. The model is an extension of a one-dimensional sediment routing model. By splitting the channel and solving the hydraulic and sediment transport equations for each channel side, lateral variability in vertical and downstream aggradation and degradation is simulated. A curvature function is used to redistribute shear stress around meander bends and bank erosion is simulated as a function of excess shear stress. The calibrated model is used to explore the impacts of human intervention including exploring channel restoration options. Current discussions are in place for engineering work on an unprotected but severely eroding 200 m reach. Modelling scenarios are used to explore the possible impacts of installing hard engineering schemes along this reach. The most

  17. Influence of varying hydraulic conditions on hyporheic exchange and reactions in an in-stream gravel bar

    NASA Astrophysics Data System (ADS)

    Trauth, Nico; Schmidt, Christian; Maier, Uli; Fleckenstein, Jan H.

    2014-05-01

    In the hyporheic zone (HZ) important biogeochemical transformations occur with crucial impact on nutrient cycling in fluvial systems. Here we investigate the interplay between stream flow and HZ exchange of a natural in-stream gravel bar (ISGB), by using three-dimensional steady state simulations of a coupled surface and subsurface numerical model. Stream flow is simulated by the open source computational fluid dynamics (CFD) software OpenFOAM. It is sequentially coupled by the hydraulic head distribution to the top boundary of the groundwater model code MIN3P, simulating flow, solute transport, aerobic respiration (AR) and denitrification (DN) in the HZ. The modelling approach is validated to the stream rating curve and the subsurface travel times in the ISGB based on field measurements. Hydraulic conditions are varied by stream discharge, ranging from low discharge, sufficient to allow stream water flow through both stream channels surrounding the ISGB (0.1 m³/s), to conditions where the ISGB is completely submerged (5.0 m³/s). Ambient groundwater flow is assigned by constant head boundaries upstream and downstream of the ISGB. By varying stream discharge or ambient groundwater heads the general flow field of the ISGB can be adjusted from losing via neutral to gaining conditions. Reactive transport scenarios consider stream water as the primary source of dissolved oxygen and dissolved organic carbon. Furthermore, two nitrate sources originated from the stream water and ambient groundwater are included in the model. Results show that highest hyporheic exchange and longest residence times occur under neutral conditions, where the extent of the hyporheic flow cell is at a maximum. Hence, the stronger the system is gaining and losing, the smaller is the hyporheic exchange flux and the shorter are the residence times in the HZ of the ISGB. AR and DN efficiencies of the ISGB are lowest under gaining conditions because infiltrating solutes are restriced to the

  18. Eroded riverbank assessing in a gravel bed reach of the Piave River by processing LiDAR and TLS data

    NASA Astrophysics Data System (ADS)

    Moretto, Johnny; Rainato, Riccardo; Rigon, Emanuel; Aristide Lenzi, Mario

    2015-04-01

    represents a valuable support for river topography description, river management, ecology and restoration purposes. Keywords: Fluvial processes; gravel bed river; riverbank erosion; LiDAR data; TLS data; vegetation filtering; erosion-deposition analysis.

  19. Implications of a Dynamic Hydromorphic Regime For Environmental Management on a Disturbed Large Gravel-Bed River

    NASA Astrophysics Data System (ADS)

    Moir, H. J.; Pasternack, G. B.

    2006-12-01

    demonstrate the importance of understanding the geomorphic and ecological context of a system before developing strategies for restoration. In the case of the LYR, a dynamic sediment supply and hydrological regime produce a heterogeneous channel morphology with associated hydraulic and sedimentary complexity that drive a diverse assemblage of habitats through the majority of the reach. Restoration measures would be most cost-effective in the ~1 km of the river immediately downstream from the dam where there is a net deficit of spawning caliber sediment. Restoration efforts (e.g., gravel augmentation) in this location may provide a disproportionately important to spawning habitat that results in a benefit to production in the system. Furthermore, the results also demonstrate that specific restoration approaches must also consider the geomorphic regime of the system. In the case of the Yuba, this means that sculpting the channel to provide specific habitat units is unlikely to be a sustainable practice given the dynamic regime of the system.

  20. Gravel deposit produced by a flash paleoflood in a succession of Quaternary terraces in the Plain of Vic (NE Iberian Peninsula)

    NASA Astrophysics Data System (ADS)

    Castelltort, Xavier; Colombo, Ferran; Carles Balasch, Josep; Barriendos, Mariano; Mazón, Jordi; Pino, David; Lluís Ruiz-Bellet, Josep; Tuset, Jordi

    2016-04-01

    In contrast with the abundance of studies of fluvial terraces, caused by river dynamics, there are very few descriptions of alluvial deposits produced by flash floods and mass movements. This study describes a late Pleistocene sedimentary deposit produced by a flash paleoflood and attempts to explain its genesis and its source areas. The Plain of Vic, drained by the river Ter and its tributaries, is one of the eastern erosive basins bordering the sedimentary Ebre basin (NE Iberian Peninsula). This plain has a length of 35 km and an average width of 8 km with a N-S direction and lies mainly on the Marls of Vic Fm. These materials are the less resistant lithologic members of the monocline Paleogene stratigraphic succession that dips to the west. The basal resistant bed that forms the eastern cuesta is the Sandstones of Folgueroles Fm. On the top, the resistant lithologic beds that form the scarp face are the sandstones of La Noguera in the Vidrà Fm. On the scarp face, various coalescent alluvial bays have been developed, which have accumulated up to eight levels of alluvial terraces. In one of them, formed by the river Mèder and the Muntanyola stream, a gravel deposit up to 5 m thick formed in a single episode outcrops, in a position T4,. A dating of the river Ter T5 has obtained an age of 117.9 ± 9.5 Ky. The accumulation of gravel erodes another level of metric thickness of the same lithological characteristics and texture. The deposit does not have any internal structure or organization of pebbles. At its base, there are several metric blocks coming directly from the slopes. The accumulation of gravel is block-supported with a sandy matrix. The pebbles size is centimetric to decimetric (90%). Its texture is subrounded. Lithologically, the deposit consists mostly of sandstone and limestone from the top of the series. On the ground, the accumulation of gravel is elongated, with a maximum length and width of 550 m by 160 m and a slope surface of 2.54%. With an area

  1. A combined Lagrangian-Eulerian approach to understand the kinematic and dynamic properties of coherent flow structures over a gravel bed

    NASA Astrophysics Data System (ADS)

    Hardy, R. J.; Best, J.; Parsons, D. R.; Keevil, G.; Rosser, N.

    2009-12-01

    Turbulence in gravel-bed rivers (GBR’s) 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. These coherent flow structures (CFS’s) are generated through topographic forcing of the typically shallow flow over the detailed micro-topography of the gravel bed. However, we currently have little understanding of the kinematic (size, scaling, shape, vorticity & energy) & dynamic (origin, stability, growth, genesis & contribution to averages) characteristics of theses CFS’s, which are central to improving our understanding of turbulent flow, the contribution of CFS’s to fluid mixing, bed shear stress and hence sediment transport. This lack of process understanding of turbulence in GBR’s stems from two fundamental shortcomings: i) previous studies have used Eulerian time series to quantitatively determine processes, which may be interpolated to examine the whole flow field, rather than studying the complete instantaneous holistic flow field; and ii) whole flow field visualization provides a qualitative Lagrangian viewpoint but very little quantitative information. Here, we demonstrate a novel turbulence mapping technique using a combined digital Particle Image Velocimetry and planar Laser-Induced Fluorescence technique to allow a combined Lagrangian-Eulerian approach to understand both the kinematic and dynamic properties coherent flow structures over a gravel bed in a flume. The results demonstrate the dynamic interplay between fluid within individual identifiable coherent flow structures and the structure themselves as the fluid advects over the bed.

  2. A critical evaluation of grid-by-number sediment sampling using laser scanner derived clast population statistics across a gravel bar

    NASA Astrophysics Data System (ADS)

    Milan, D. J.; Heritage, G. L.

    2007-12-01

    Water flow level in river channels is moderated by the interaction with the roughness of the surface over which it flows. The interaction is highly complex and remains poorly understood despite its economic and social importance in flood level forecasting. The empirical and semi-rational nature of approaches used to estimate hydraulic roughness makes them very difficult to apply and much of the hydraulic resistance has been attributed to grain roughness using various forms of the Colebrook-White equation where the grain diameter is modified by a multiplier to account for the non-uniform nature of gravel-bed surfaces. Fundamental to the accuracy of the particle size approaches is the sampling of river-bed gravels where sample size, operator bias, particle shape and surface heterogeneity can greatly affect the result. Despite these problems a standard surface sample of the intermediate axis of 100 clasts remains the accepted method for grain-size characterisation amongst scientists and engineers concerned with channel hydraulics. Surface roughness has also been measured using a random field of spatial elevation data. The success of this approach has been tempered by the lack of high-resolution topographic data covering all roughness scales, however, improved data-point resolution is now achievable using terrestrial laser scanning technology. The aim here is to reliably quantify the population grain-size distribution of a natural gravel surface using random field terrestrial laser scanner x,y,z data and by direct comparison to demonstrate the errors inherent in the conventional particle-size approach. Application of the random field approach, using a terrestrial laser scanner, across a gravel bar surface on the River South Tyne at Lambley, UK, generated an effective sample of 120,000 clasts yielding a D84 for use in the Colebrook White equation of 0.110m. Monte Carlo sampling within the 12000 measured clasts from the bar surface generated 560 simulated grid

  3. Hydrodynamic controls on the downstream elimination of gravel, and implications for fluvial-deltaic stratigraphy: two end-member case studies from the Selenga River, Russia, and the Mississippi River, U.S.A.

    NASA Astrophysics Data System (ADS)

    Nittrouer, J. A.

    2015-12-01

    The downstream termination of gravel is measured for two fluvial-deltaic systems: the Selenga and Mississippi rivers. These end-members vary by an order of magnitude for slope, water and sediment discharge, and delta area. Moreover, the contrast between the tectonic regimes of the receiving basins is stark: the Selenga delta is located along the deep-water margin of Lake Baikal, which is an active half-graben rift basin, while the Mississippi discharges onto a passive margin with little tectonic influence. Nevertheless, the two rivers share a striking sedimentological similarity: near the delta apex, gravel is eliminated from the downstream dispersal system, and so sediment reaching the land-water interface is exclusively sand and mud. Field data for both rivers, including sediment samples and water discharge and flow velocity measurements, are used to validate morphodynamic models that assess the downstream changes in fluid stress and gravel transport. The analyses show that there are two distinct mechanisms that drive gravel deposition and prohibit dispersal throughout the delta. For the Selenga, water partitioning among bifurcating channels produces a non-linear reduction in shear stress and gravel deposition. For the Mississippi, backwater flow arrests the downstream movement of gravel during low and moderate water discharges, and although floods overcome backwater and produce uniform flow to the outlet, the duration of floods is too short to disperse gravel throughout the delta. Given sufficient time, model results indicate that both rivers should approach morphodynamic equilibrium, whereby aggradation due to sediment deposition raises local bed slope and sediment transport capacity, thereby facilitating downstream gravel movement. However, both systems possess unique characteristics that prevent this process from occurring. For the Selenga, tectonically induced movements regularly down drop portions of the delta below base level, forcing renewed delta

  4. Geomorphic change along a gravel bed river affected by volcanic eruption: Rio Blanco - Volcan Chaiten (South Chile)

    NASA Astrophysics Data System (ADS)

    Picco, Lorenzo; Ravazzolo, Diego; Ulloa, Hector; Iroumé, Andres; Aristide Lenzi, Mario

    2014-05-01

    Gravel bed rivers are environments shaped by the balance of flow, sediment regimes, large wood (LW) and vegetation. Geomorphic changes are response to fluctuations and changes of runoff and sediment supply involving mutual interactions among these factors. Typically, many natural disasters (i.e. debris flows, floods and forest fires) can affect the river basin dynamics. Explosive volcanic eruptions present, instead, the potential of exerting severe impacts as, for example, filling river valleys or changing river network patterns thanks to massive deposition of tephra and volcanic sediment all over the main channel and over the basin. These consistent impacts can strongly affect both hydrology and sediment transport dynamics, all over the river system, producing huge geomorphic changes. During the last years there has been a consistent increase in the survey technologies that permit to monitor geomorphic changes and to estimate sediment budgets through repeat topographic surveys. The calculation of differences between subsequent DEMs (difference of DEMs, DoD) is a commonly applied method to analyze and quantify these dynamics. Typically the higher uncertainty values are registered in areas with higher topographic variability and lower point density. This research was conducted along a ~ 2.2 km-long sub-reach of the Blanco River (Southern Chile), a fourth-order stream that presents a mainly rainfall regime with winter peak flows. The May 2008 Chaitén volcanic eruption strongly affected the entire Rio Blanco basin. The entire valley was highly exposed to the pyroclastic and fluvial flows, which affected directly a consistent area of evergreen forests. Extreme runoff from the upper Blanco catchment aggraded the channel and deposited up to several meters of tephra, alluvium, and LW along the entire river system. Aims of this contribution are to define and quantify the short term evolution of the Blanco River after the big eruption event and a subsequent consistent

  5. A 1-D Size Specific Numerical Model for Gravel Transport That Includes Sediment Exchange with a Floodplain

    NASA Astrophysics Data System (ADS)

    Lauer, Wesley; Viparelli, Enrica; Piegay, Herve

    2014-05-01

    bed armor near the upstream end of the study reach, where sediment load has been disrupted. The inclusion of active exchange with the floodplain allows the floodplain evolve into a net source of bed material sediment as the channel incises. This effect prevents the sediment deficit from reaching the confluence with the Rhone for several simulated decades. When spatially variable migration rates similar to those measured from aerial photography are used to drive sediment exchange, the model shows complex interaction between bed and bank sediment, with the relatively fine-grained bank sediment supply mobilizing the coarser fraction of the active layer within rapidly shifting portions of the channel. This increases overall transport rates and leads to additional channel incision relative to what is simulated without bank sediment supply in these rapidly shifting reaches. The model is also helpful for evaluating the potential reach-scale effects of gravel augmentation downstream of the dams.

  6. Simulation of ground-water flow in an unconfined sand and gravel aquifer at Marathon, Cortland County, New York

    USGS Publications Warehouse

    Miller, Todd S.

    2000-01-01

    The Village of Marathon, in Cortland County, N.Y., has three municipal wells that tap a relatively thin (25 to 40 feet thick) and narrow (less than 0.25 mile wide) unconfined sand and gravel aquifer in the Tioughnioga River valley. Only one of the wells is in use because water from one well has been contaminated by petroleum chemicals from a leaking storage tank, and water from the other well contains high concentrations of manganese. The operating well pumps about 0.1 million gallons per day and supplies about 1,000 people. A three-dimensional, finite-difference ground-water-flow model was used to (1) compute hydraulic heads in the aquifer under steady-state conditions, (2) develop a water budget, and (3) delineate the areas contributing recharge to two simulated wells that represent two of the municipal wells: one 57 feet east of the Tioughnioga River, the other 4,000 feet to the south and 75 feet from a man-made pond. The water budget for simulated long-term average, steady-state conditions with two simulated pumping wells indicates that the principal sources of recharge to the unconfined aquifer are unchanneled runoff and ground-water inflow from the uplands (41 percent of total recharge), precipitation that falls directly on the aquifer (34 percent), and stream leakage (23 percent). Only 2 percent of the recharge to the aquifer is from ground-water underflow into the northern end of the modeled area. Most of the simulated groundwater discharge from the modeled area (78 percent of total discharge) is to the Tioughnioga River; the rest discharges to the two simulated wells (19 percent) and as underflow at the southern end of the modeled area (3 percent). Results of a particle-tracking analysis indicate that the aquifer contributing area of the northern (simulated) well is 0.10 mile wide and 0.15 mile long and encompasses 0.015 square miles; the contributing area of the southern (simulated) well is 0.20 mile wide and 0.11 mile long and encompasses 0.022 square

  7. Bed clusters in humid perennial and Mediterranean ephemeral gravel-bed streams: The effect of clast size and bed material sorting

    NASA Astrophysics Data System (ADS)

    Wittenberg, L.; Laronne, J. B.; Newson, M. D.

    2007-02-01

    SummaryA short review of the literature on particle clusters on gravel river beds reveals investigations of both process and form dominated by the intensive study approach, using a restricted geographical sample or evidence from flumes. An alternative, presented here, is extensive sampling - from three climatic zones, several channels in each and at multiple transects at each site. It uses insights provided by a more intensively studied 'base station' [Wittenberg, L., Newson, M.D., 2005. Particle clusters in gravel-bed rivers - an experimental morphological approach to bed material transport and stability concepts. Earth Surface Processes and Landforms 30(11), 1351-1368]. Transect surveys were completed in each selected reach to establish flow_depth, bed material size and bed structure. A total of more than 5000 sample points reveals the vital presence of bed material of ≈100 mm D50 for all sub-types of clusters to occur; thereafter, cluster frequency relates directly to the D90, with an improving correlation at D90 > 256 mm. A better integration of data from the diverse hydrological/hydraulic regimes can be achieved by correlating cluster frequency with a sorting index for bed material. Further analysis of hydrological and hydraulic data for all sites is required to develop a dynamic explanation.

  8. Numerical modeling of gravel bed river response to meander straightening: The coupling between the evolution of bed pavement and long profile

    NASA Astrophysics Data System (ADS)

    Talbot, Tracey; Lapointe, Michel

    2002-06-01

    Artificial meander straightening (rectification) was conducted in the early 1960s along the Sainte-Marguerite River, Canada, in order to facilitate highway construction along the valley. Previous studies [Talbot and Lapointe, 2002] confirm that vertical reprofiling, coupled with pavement coarsening in the degrading reach, were the main responses counteracting the disequilibrium in gravel transport rates triggered at rectification of this system. Numerical simulations, using SEDROUT2.0, a one-dimensional hydraulic and sediment transport model, and validated against the observed channel response, show the important role played by an advancing wave of pavement coarsening down the rectified reach in modulating the bed degradation response. Simulations extending into the future reveal an asymptotically slowing approach to equilibrium in the middle of the 21st century, with a response half-time of the order of 10 years. In near-threshold gravel bed systems like the Sainte-Marguerite River, pavement coarsening after rectification buffers the system against extreme degradation. Most significantly for watershed management, this also appears to severely limit the extent of propagation of degradation upstream of the rectification.

  9. Investigating the evolution of gravel bar at river confluence during flood events using a 2D many-fraction river morphodynamic model

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Wu, F.; Ecohydraulics Lab.

    2010-12-01

    The knowledge of river morphology is fundamental and useful information for engineering and habitat restoration purposes. Many interesting phenomena such as armoring and downstream fining significantly affect the quality of riverine habitats. These phenomena could be even more devastating when they occur during the extreme flood events. Therefore, the development of meso-scale bedforms during flood events and the change in their sediment composition have become important topics of study. However, the complex interactions between flood flow, nonuniform particles and sediment transport make these problems difficult to tackle. In this study, we develop a 2D (two-dimensional) many-fraction FE (finite element) morphodynamic model to investigate the evolution of gravel bar during flood events. The proposed model adopts the characteristic dissipative Galerkin (CDG) scheme such that the convection-dominated bar evolution can be computed without numerical instabilities. A two-year record of DEM (digital elevation model) is obtained by airborne Lidar at the confluence of the Xin-Dian River (Taiwan), which is used to verify the model results. The proposed model is further applied to determine the best operation scheme of the Feitsui reservoir for mitigating blockage of river confluence by the gravel bar and sustaining the bed composition favorable to the river biota.

  10. A pilot scale trickling filter with pebble gravel as media and its performance to remove chemical oxygen demand from synthetic brewery wastewater*

    PubMed Central

    Habte Lemji, Haimanot; Eckstädt, Hartmut

    2013-01-01

    Evaluating the performance of a biotrickling filter for the treatment of wastewaters produced by a company manufacturing beer was the aim of this study. A pilot scale trickling filter filled with gravel was used as the experimental biofilter. Pilot scale plant experiments were made to evaluate the performance of the trickling filter aerobic and anaerobic biofilm systems for removal of chemical oxygen demand (COD) and nutrients from synthetic brewery wastewater. Performance evaluation data of the trickling filter were generated under different experimental conditions. The trickling filter had an average efficiency of (86.81±6.95)% as the hydraulic loading rate increased from 4.0 to 6.4 m3/(m2∙d). Various COD concentrations were used to adjust organic loading rates from 1.5 to 4.5 kg COD/(m3∙d). An average COD removal efficiency of (85.10±6.40)% was achieved in all wastewater concentrations at a hydraulic loading of 6.4 m3/(m2∙d). The results lead to a design organic load of 1.5 kg COD/(m3∙d) to reach an effluent COD in the range of 50–120 mg/L. As can be concluded from the results of this study, organic substances in brewery wastewater can be handled in a cost-effective and environmentally friendly manner using the gravel-filled trickling filter. PMID:24101209

  11. Geophysical and GIS study of gravel layer on Gyöngyös plain and Kőszeghegyalja, W-Hungary

    NASA Astrophysics Data System (ADS)

    Szabó, Vera; Kovács, Gabor

    2014-05-01

    The Western-Hungarian Gravel Cover (WHCG) is located between the Eastern Alps and the Danube Basin, surrounded by the Rába, Ikva, Pinka rivers, Kőszeg-Rechnitz and Sopron Mountains. The extension of the gravelly sediment coverage is approximately 3000 km2, the volume is ~30 million cubicmeter. The layers thickness changes between 5-35 m. My research area is limited to the Gyöngyös Plain which northern side belongs to the Kőszeghegyalja is also the part of the WHGC. The western boundary of this region is the wide, flat valley of the Gyöngyös stream, the northern is the Répce's asimmetric, steep valley. The plain itself has a very low angle, even slope to southeastern direction. The elevation of the plain is 190-260 meter above sea level. The northern side is more fragmented, incised by asimmetric valleys. The hight of this area could form a contiguous flat tilted surface with a consistent slope. The slope conditions of the plain are changing nearby Acsád village, becoming slightly steeper and tilted to east immediately next to a narrow ridge extending northward. This ridge is the eastern boundary of a 2 km wide depression with a steeper northern side flattened to southward. The purpose of my study is to explore the geometry of gravel layer and to infer the processes that could create it. Firstly I made a database from borehole descriptions collected from the research area. This database as basis for interpolated GIS models, show the gravels material properties, extension, distribution of thickness in a large scale depend on a borehole density. I compared these surfaces with Digital Terrain Models with SRTM- and a more detailed model, created from Hungarian National Grid map sheets (1:10 000). Golden Software Surfer and Global Mapper were used to interpolate, represent and interpret these surfaces. The models with the detailed borehole data show a 1-3 meter thick unsorted, unstratified gravel layer with reddish brown coloured clay or brown loam matrix. The

  12. Suitability analysis for sand and gravel extraction site location in the context of a sustainable development in the surroundings of Zaragoza (Spain)

    NASA Astrophysics Data System (ADS)

    Lamelas, M. T.; Marinoni, O.; Hoppe, A.; de La Riva, J.

    2008-10-01

    Zaragoza city is located in the central Ebro Basin, in the Iberian Peninsula. The fluvial terraces formed by the Ebro River present a valuable resource of sand and gravel deposits. However, taking advantage of these available resources implies conflicts with other land use interests like urban and industrial development as well as agricultural use, which has also traditionally occupied the alluvial terraces. These deposits represent a substantial groundwater resource that should be preserved for future generations. The development of spatial decision support systems (SDSS) has greatly assisted efforts for solving land-use conflicts. These systems combine the benefits of geographic information systems (GIS) and decision support methodologies and are therefore suitable to manage sustainable development of urban areas. In this contribution, an extraction suitability map taking into consideration a variety of environmental criteria is created with the help of a SDSS. The method used is the analytical hierarchy process which is integrated in ArcGIS. Areas most suitable to sand and gravel extraction are located in the high terraces, and in those terraces covered by pediments where the thickness of resource is relatively high. These areas are far from valuable natural areas, outside areas most vulnerable to groundwater contamination, and beneath soils with poor irrigation characteristics.

  13. SUBMERGED GRAVEL SCRUBBER DEMONSTRATION AS A PASSIVE AIR CLEANER FOR CONTAINMENT VENTING AND PURGING WITH SODIUM AEROSOLS -- CSTF TESTS AC7 - AC10

    SciTech Connect

    HILLIARD, R K.; MCCORMACK, J D.; POSTMA, A K.

    1981-11-01

    Four large-scale air cleaning tests (AC7 - AC10) were performed in the Containment Systems Test Facility (CS'lF) to demonstrate the performance of a Submerged Gravel Scrubber for cleaning the effluent gas from a vented and purged breeder reactor containment vessel. The test article, comprised of a Submerged Gravel Scrubber (SGS) followed by a high efficiency fiber demister, had a design gas flow rate of 0.47 m{sup 3}/s (1000 ft{sup 3}/min) at a pressure drop of 9.0 kPa (36 in. H{sub 2}O). The test aerosol was sodium oxide, sodium hydroxide, or sodium carbonate generated in the 850-m{sup 3} CSTF vessel by continuously spraying sodium into the air-filled vessel while adding steam or carbon dioxide. Approximately 4500 kg (10,000 lb) of sodium was sprayed over a total period of 100 h during the tests. The SGS/Demister system was shown to be highly efficient (removing ~99.98% of the entering sodium aerosol mass), had a high mass loading capacity, and operated in a passive manner, with no electrical requirement. Models for predicting aerosol capture, gas cooling, and pressure drop are developed and compared with experimental results.

  14. Analytical and numerical simulation of the steady-state hydrologic effects of mining aggregate in hypothetical sand-and-gravel and fractured crystalline-rock aquifers

    USGS Publications Warehouse

    Arnold, L.R.; Langer, William H.; Paschke, Suzanne Smith

    2003-01-01

    Analytical solutions and numerical models were used to predict the extent of steady-state drawdown caused by mining of aggregate below the water table in hypothetical sand-and-gravel and fractured crystalline-rock aquifers representative of hydrogeologic settings in the Front Range area of Colorado. Analytical solutions were used to predict the extent of drawdown under a wide range of hydrologic and mining conditions that assume aquifer homogeneity, isotropy, and infinite extent. Numerical ground-water flow models were used to estimate the extent of drawdown under conditions that consider heterogeneity, anisotropy, and hydrologic boundaries and to simulate complex or unusual conditions not readily simulated using analytical solutions. Analytical simulations indicated that the drawdown radius (or distance) of influence increased as horizontal hydraulic conductivity of the aquifer, mine penetration of the water table, and mine radius increased; radius of influence decreased as aquifer recharge increased. Sensitivity analysis of analytical simulations under intermediate conditions in sand-and-gravel and fractured crystalline-rock aquifers indicated that the drawdown radius of influence was most sensitive to mine penetration of the water table and least sensitive to mine radius. Radius of influence was equally sensitive to changes in horizontal hydraulic conductivity and recharge. Numerical simulations of pits in sand-and- gravel aquifers indicated that the area of influence in a vertically anisotropic sand-and-gravel aquifer of medium size was nearly identical to that in an isotropic aquifer of the same size. Simulated area of influence increased as aquifer size increased and aquifer boundaries were farther away from the pit, and simulated drawdown was greater near the pit when aquifer boundaries were close to the pit. Pits simulated as lined with slurry walls caused mounding to occur upgradient from the pits and drawdown to occur downgradient from the pits. Pits

  15. Sediment tracing from small torrential channels to gravel-bed rivers using pit tags method. A case study from the upper Guil catchment.

    NASA Astrophysics Data System (ADS)

    Graff, Kévin; Viel, Vincent; Carlier, Benoit; Lissak, Candide; Arnaud-Fassetta, Gilles; Fort, Monique; Madelin, Malika

    2016-04-01

    In mountainous areas, especially in large catchments with torrential tributaries, the production and sediment transport significantly increase flood impacts in the valley bottoms. The quantification and characterisation of sedimentary transfers are therefore major challenges to provide better flood risk management. As a part of SAMCO (ANR 12 SENV-0004 SAMCO) project, for mountain hazard assessment in a context of global changes, we tried to improve the knowledge of these hydromorphological systems at both spatial and temporal scales, by identifying sediment supply and sediment dynamics from torrential tributaries to the main channel. A sediment budget was used as a tool for quantifying erosion, transport and deposition processes. This research is focused on the upper Guil catchment (Queyras, Southern French Alps - 317 km2) entrenched in "schistes lustrés" and ophiolitic bedrock. This catchment is prone to catastrophic summer floods [June 1957 (>R.I. 100 yr), June 2000 (R.I. 30 yr)] characterised by huge sediment transport from tributaries to downvalley, very much facilitated by strong hillslope-channel connectivity (about 12,000 m3 volume of sediment aggraded in the Peyronnelle fan during the June 2000 RI-30 year flood event). We intend to highlight sediment dynamics on small torrential channels and its connection with gravel-bed streams. Four study sites characterised by avalanche and debris flow-dominated channels located in the upper Guil catchment were investigated. In order to better assess sediment movement, we used the pit-tags technique. In total, 560 pit-tags (pt) have been implemented in four catchments: Peyronnelle (320pt), Combe Morel (40pt), Bouchouse (120pt), and Maloqueste (80pt). Distances and trajectories of gravels sediments have been monitored since two years during summer periods. We specifically describe results obtained along the Peyronnelle channel affected by a large debris-flow during august 2015. Data are used to discuss lag time

  16. Study of morphological changes of a gravel-bed braided river with a combined analysis of airborne LiDAR and archive aerial photographs (French Prealps)

    NASA Astrophysics Data System (ADS)

    Lallias-Tacon, S.; Liébault, F.; Piégay, H.; Leduc, P.

    2012-04-01

    The recent development of innovative topographic survey technologies offers new opportunities for investigating spatial and temporal patterns of gravel-bed rivers morphological responses to flood events. In this study, multidate airborne LiDAR surveys were used to reconstruct reach-scale morphological changes of a gravel-bed braided river following a channel-forming flood event. LiDAR surveys were acquired in October 2008 and June 2010 for a 7-km reach of the Bès River, a very active aggrading braided channel, which is a tributary to the Bléone River in the Southern French Prealps (drainage area: 234 km2). Between these two dates, a 15-year flood occurred in December 2009, with a peakflow discharge of 171 m3 s-1. A DEM of difference (DoD) was produced by subtraction of LiDAR-derived DTM pair. Spatially distributed error in Dod was accounted with dGPS field measurement by sampling of different types of terrains (exposed gravel bars, spares and dense vegetated areas). The scour and fill maps allowed reconstructing erosion and deposition of bedforms and provide a volume estimate for calculating a sediment budget. These bedforms were described by different factors like their geometry (width, shape), their position and elevation relative to the main low-flow channel and their vegetation cover. Bed morphology was also studied by extracting different metrics at regularly-spaced cross-sections to infer information about sediment transfer in the braided channel. Final aim is to link bedform characteristics with their morphological response. Morphological changes were also studied in a historical context with a series of aerial photographs (1948-2010) to link the present-day morphology of the river with longer term channel changes. Active channel and island area were measured at reach and sub-reach scales (50 m), as well as active channel and island widths for cross-sections (every 10 m along). These variables were coupled with landscape changes and hydrological events in

  17. Thermal variability within the hyporheic zone of an Alpine stream gravel bar is influenced by solar radiation and other climatic factors

    NASA Astrophysics Data System (ADS)

    Boodoo, Kyle; Schelker, Jakob; Battin, Tom

    2016-04-01

    Gravel bars with largely unsubmerged surface areas exposed to the atmosphere are recipient to high levels of incoming radiation during the day, particularly during summer months. Transfer of heat from the atmosphere downward into the hyporheic zone (HZ) below a gravel bar (GB) can thus possibly lead to the alteration of the vertical temperature profile within its HZ, with implications for physical and biogeochemical processes therein. Here we present results from the analysis of seasonal, high frequency spatio-temporal data including, vertical hyporheic temperature, physical parameters and climatic data for a GB located within an Alpine cold water stream (Oberer Seebach, Austria). Vertical temperature profiles throughout the GB were analyzed together with corresponding climatic data for different seasons to elucidate the spatio-temporal variability of HZ temperature gradients in relation to air temperature, incoming global radiation and stream discharge.Initial analyses indicate a clear seasonal difference between Summer and Autumn temperature profiles throughout the GB, with a strongly developed, exponentially decreasing temperature-depth gradient throughout the GB during summer months. In contrast, this observed gradient substantially weakened or collapsed during autumn months. Furthermore, the highest absolute temperatures and steepest depth gradients within the HZ occurred during summer days, coinciding with the falling hydrograph,where hyporheic temperatures exceeded that of both surface water and groundwater. These findings point to the effect of solar radiation and/or air temperature as a contributor to GB temperatures, possibly influencing diurnal and seasonal GB temperature profiles.Overall, our results suggest that not only the mixing of groundwater and streamwater, but also heat transfer associated with solar radiation and/or air temperature may act as an important driver of HZ temperature, particularly during summer months. This may have implications

  18. Modeling the Importance of Baseflow and Sediment Supply on Armor Development: Contrasting Intermittent Dryland and Perennially-Flowing Gravel-Bedded Rivers

    NASA Astrophysics Data System (ADS)

    Goodwin, K.; Johnson, J. P.; Viparelli, E.

    2014-12-01

    Most gravel-bedded rivers with perennial base flow are often armored, defined as having a bed surface grain size distribution that is coarser than the subsurface. In contrast, ephemerally flowing rivers, which are commonly flash flood-dominated, are typically unarmored. Although both types of channels have high peak discharges during floods, a key difference between these hydrological settings is in flow intermittency and how much flow occurs during moderate and low flow periods. High sediment supply and elevated shear stresses during floods have been identified as processes that may reduce or prevent armor development, but the preferential transport of smaller grain sizes during lower flows may also strongly affect armor development. We use numerical modeling to explore the relative importance of these armor-related processes. Calculations are based on a previous model called the Spawning Gravel Refresher, which includes mixed grain size sediment transport, morphodynamic feedbacks with channel slope, variable discharge hydrographs, and interactions with the subsurface grain sizes as the bed surface aggrades and erodes. Model runs are calibrated to natural rivers with varying degrees of bed surface armoring and flood hydrograph shape. These natural rivers include: i) the Nahal Yatir, an ephemerally flowing unarmored river in the Negev Desert, Israel, and ii) Trinity River, California, a larger perennially flowing, armored mountain river with annual snowmelt floods. We present a thorough exploration of model parameters, including base flow duration and magnitude, flood hydrograph shape and sand supply, combined with data from natural rivers. This produces quantitative bounds on how armor development varies in a wide range of parameter spaces unobtainable in the field alone.

  19. Pesticides and nitrate in surficial sand and gravel aquifers as related to modeled contamination susceptibility in part of the Upper Mississippi River Basin

    USGS Publications Warehouse

    Hanson, Paul E.

    1998-01-01

    The occurrence of pesticides and nitrate (nitrite plus nitrate as nitrogen) in surficial sand and gravel aquifers in parts of Minnesota and Wisconsin was summarized as part of an analysis of historical water-quality data for the Upper Mississippi River Basin study unit of the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program. Water samples were collected by State and Federal agencies for pesticides (366) and nitrate (410) between 1971 and 1994 from wells completed in surficial sand and gravel aquifers. State agencies in Minnesota and Wisconsin have developed models to determine areas where ground water is susceptible to contamination based on geologic and hydrologic conditions (Schmidt, 1987, and Porcher, 1989). Water-quality data is evaluated with respect to the ground-water susceptibility models. The results also are evaluated with respect to overlying land use and land cover. Samples from wells with detectable levels of one or more pesticides or nitrate concentrations exceeding the U.S. Environmental Protection Agency's (USEPA) Maximum Contaminant Level (MCL) of 10 milligrams per liter (mg/L) generally coincided with areas of high contamination susceptibility. Furthermore, samples from wells located in areas of high contamination susceptibility had pesticide detection frequencies and nitrate concentrations that correlated to overlying land use and land cover. Samples from wells located in high susceptibility areas that were surrounded by cropland had greater pesticide detection frequencies and greater nitrate concentrations than wells located in similar susceptibility areas but surrounded by different land use and land cover types such as forest, urban, and wetlands.

  20. Co-evolution of in-channel sediment deposition and channel widening. The case of the gravel-bed Dunajec River upstream from the Czorsztyn Reservoir, Polish Carpathians.

    NASA Astrophysics Data System (ADS)

    Liro, Maciej

    2015-04-01

    In this study the changes of the gravel bar area and the channel width were analysed in the base-level raised section of the gravel-bed Dunajec River upstream from the Czorsztyn Reservoir (CR) (Polish Carpathians). The construction of the CR and the large flood which occurred in 1997, as well as the existence of aerial imagery taken before (1982, 1994) and after (2003) those events during very similar and low river discharges, provided unique opportunity to investigate temporal and spatial changes of channel width and bar area. In the post-dam period (1994-2003), a major flood in 1997 caused more than two times greater channel widening and ten-fold greater bar area increasing in the backwater section than in the section not affected by base-level rising. The extents of accelerated channel widening and bar area growing in the longitudinal channel profile reached 2400 m and 1800 m upstream from the CR respectively. The highest channel widening and the bar growth were spatially related to the highly developing meander bends located partly at the upstream limit of the backwater (1400-2400 m). In this section, very wide braided channel existed at end of the 19th century. This study shows that the reservoir-induced base-level rising may have promoted the sediment storage and major channel change, but the trajectories of these phenomenons are temporally related to floods, and spatially and casually interdependent on local site specific conditions (e.g. bend development site in wider valley bottom section). In this site the existence of negative feedback mechanisms between bar growth and channel widening resulted in a progressive channel widening and large bar development.

  1. Using aerated gravel-packed contact bed and constructed wetland system for polluted river water purification: A case study in Taiwan

    NASA Astrophysics Data System (ADS)

    Lin, J. L.; Tu, Y. T.; Chiang, P. C.; Chen, S. H.; Kao, C. M.

    2015-06-01

    The Ju-Liao Stream is one of the most contaminated streams in Kaohsiung City, Taiwan. A constructed wetland (CW) system was built in 2010 for polluted stream water purification and ecosystem improvement. An aerated gravel-packed contact bed (CB) system was built in 2011 and part of the stream water was treated by the CB before discharging to the CW. The influent rates of the CW and CB were approximately 5570 and 900 m3/d, respectively. The CW contained one free-water surface basin planted with emergent wetland plants, followed by the plug-flow channel-shaped free-water surface basin planted with emergent and floating wetland plants. The mean measured hydraulic loading rate (HLR), hydraulic retention time (HRT), water depth, and total volume of wetland system were 1.7 m/d, 0.68 d, 0.7 m, and 4400 m3, respectively. The aeration zone of the CB system had a dimension of 24 m (L) × 8 m (W) × 3 m (H), which was filled with gravels (average diameter = 5 cm) with a porosity of 0.4, and the aeration rate was 7.8 m3/min. Results show that the CB system was able to remove 69% of suspended solid (SS), 86% of biochemical oxygen demand (BOD), and 58% of total nitrogen (TN). Up to 82% of BOD and 27% of TN could be removed in the CW system. Removal efficiency of SS was affected by the growth of chlorophyll a in the CW system due to the growth of algae. The observed first-order decay rates (k) for BOD and TN in CB were 9.3 and 4.2 1/d, and the k values for BOD and TN removal in CW were 2.5 and 0.45 1/d. The high pollutant removal efficiencies in the CB system indicate that the system could enhance the organic and nutrient removal through the biological processes effectively. Sediments contained high total organic matter (1.9-4.5%), sediment total nitrogen (6.4-10.1 g/kg), sediment total phosphorus (0.59-0.94 g/kg), and sediment oxygen demand (0.9-4.1 g O2/m2 d). The organic and nutrient-abundant sediments resulted in reduced conditions (oxidation-reduction potential measurements

  2. The in-situ decontamination of sand and gravel aquifers by chemically enhanced solubilization of multiple-component DNAPLS with surfactant solutions. Topical report

    SciTech Connect

    1995-01-01

    Laboratory, numerical simulation, and field studies have been conducted to assess the potential use of micellar-surfactant solutions to solubilize chlorinated solvents contaminating sand and gravel aquifers. Laboratory studies were conducted at the State University of New York at Buffalo (SUNY) while numerical simulation and field work were undertaken by INTERA Inc. in collaboration with Martin Marietta Energy Systems Inc. at the Paducah Gaseous Diffusion Plant (PGDP) in Kentucky. Ninety-nine surfactants were screened for their ability to solubilize trichloroethene (TCE), perchloroethylene (PCE), and carbon tetrachloride (CTET). Ten of these were capable of solubilizing TCE to concentrations greater than 15,000 mg/L, compared to its aqueous solubility of 1,100 mg/L. Four surfactants were identified as good solubilizers of all three chlorinated solvents. Of these, a secondary alcohol ethoxylate was the first choice for in situ testing because of its excellent solubilizing ability and its low propensity to sorb. However, this surfactant did not meet the Commonwealth of Kentucky`s acceptance criteria. Consequently, it was decided to use a surfactant approved for use by the Food and Drug Administration as a food-grade additive. As a 1% micellar-surfactant solution, this sorbitan monooleate has a solubilization capacity of 16,000 mg TCE/L, but has a higher propensity to sorb to clays than has the alcohol ethoxylate.

  3. Analysis of conservative tracer measurement results using the Frechet distribution at planted horizontal subsurface flow constructed wetlands filled with coarse gravel and showing the effect of clogging processes.

    PubMed

    Dittrich, Ernő; Klincsik, Mihály

    2015-11-01

    A mathematical process, developed in Maple environment, has been successful in decreasing the error of measurement results and in the precise calculation of the moments of corrected tracer functions. It was proved that with this process, the measured tracer results of horizontal subsurface flow constructed wetlands filled with coarse gravel (HSFCW-C) can be fitted more accurately than with the conventionally used distribution functions (Gaussian, Lognormal, Fick (Inverse Gaussian) and Gamma). This statement is true only for the planted HSFCW-Cs. The analysis of unplanted HSFCW-Cs needs more research. The result of the analysis shows that the conventional solutions (completely stirred series tank reactor (CSTR) model and convection-dispersion transport (CDT) model) cannot describe these types of transport processes with sufficient accuracy. These outcomes can help in developing better process descriptions of very difficult transport processes in HSFCW-Cs. Furthermore, a new mathematical process can be developed for the calculation of real hydraulic residence time (HRT) and dispersion coefficient values. The presented method can be generalized to other kinds of hydraulic environments. PMID:26126688

  4. Beachrock formation in temperate coastlines: examples in sand-gravel beaches adjacent to the Nerbioi-Ibaizabal Estuary (Bilbao, Bay of Biscay, North of Spain).

    PubMed

    Arrieta, N; Goienaga, N; Martínez-Arkarazo, I; Murelaga, X; Baceta, J I; Sarmiento, A; Madariaga, J M

    2011-10-01

    Beachrocks are coastal sedimentary formations resulting from a relative rapid cementation of beach sediments by the precipitation of carbonate cements. These lithified structures are not usually observed at temperate settings. The present work is focused on the occurrence of a significant intertidal cementation in sand-gravel beaches formed among 43°N latitude coastline, close to the Nerbioi-Ibaizabal estuary (Bilbao, Bay of Biscay, North of Spain). Raman micro-spectroscopy combined with SEM-EDX analyses and petrographic descriptions have been applied for the determination of the cement generations and the cemented materials compositions of the beachrock outcrops. In general terms, the cements described were: Cement Generation 1 (CG 1, aragonite, high-magnesium calcite and silicate mixtures), Cement Generation 2 (CG 2, aragonite) and Cement Generation 3 (CG 3, mixtures of CaCO(3) polymorphs and iron oxides). The rest of the interstitial porosity of the rocks appeared either empty or filled with heterogeneous cemented mixtures of previously reworked compounds. The mineralogy, the regular distribution and the isopachous character of the carbonate cements together with the accurate cementation at advanced seaward bands propose a possible marine-phreatic context for the beachrock formation. However, the impure cements and the materials covering the interstitial porosity seem to be the result of both, the weathering actions consequences and the surface alterations of specific grains. Moreover, the presence of modern cemented materials (e.g. slag, bricks and pebbles) suggest a recent formation of the phenomenon. PMID:21420895

  5. An Impact Evaluation of a Federal Mine Safety Training Regulation on Injury Rates Among US Stone, Sand, and Gravel Mine Workers: An Interrupted Time-Series Analysis

    PubMed Central

    Windsor, Richard

    2010-01-01

    Objectives. We evaluated the impact of a safety training regulation, implemented by the US Department of Labor's Mine Safety and Health Administration (MSHA) in 1999, on injury rates at stone, sand, and gravel mining operations. Methods. We applied a time-series design and analyses with quarterly counts of nonfatal injuries and employment hours from 7998 surface aggregate mines from 1995 through 2006. Covariates included standard industrial classification codes, ownership, and injury severity. Results. Overall crude rates of injuries declined over the 12-year period. Reductions in incident rates for medical treatment only, restricted duty, and lost-time injuries were consistent with temporal trends and provided no evidence of an intervention effect attributable to the MSHA regulation. Rates of permanently disabling injuries (PDIs) declined markedly. Regression analyses documented a statistically significant reduction in the risk rate in the postintervention time period (risk rate = 0.591; 95% confidence interval = 0.529, 0.661). Conclusions. Although a causal relationship between the regulatory intervention and the decline in the rate of PDIs is plausible, inconsistency in the results with the other injury-severity categories preclude attributing the observed outcome to the MSHA regulation. Further analyses of these data are needed. PMID:20466960

  6. Appearance of Planktothrix rubescens Bloom with [D-Asp3, Mdha7]MC–RR in Gravel Pit Pond of a Shallow Lake-Dominated Area

    PubMed Central

    Vasas, Gábor; Farkas, Oszkár; Borics, Gábor; Felföldi, Tamás; Sramkó, Gábor; Batta, Gyula; Bácsi, István; Gonda, Sándor

    2013-01-01

    Blooms of toxic cyanobacteria are well-known phenomena in many regions of the world. Microcystin (MC), the most frequent cyanobacterial toxin, is produced by entirely different cyanobacteria, including unicellular, multicellular filamentous, heterocytic, and non-heterocytic bloom-forming species. Planktothrix is one of the most important MC-producing genera in temperate lakes. The reddish color of cyanobacterial blooms viewed in a gravel pit pond with the appearance of a dense 3 cm thick layer (biovolume: 28.4 mm3 L−1) was an unexpected observation in the shallow lake-dominated alluvial region of the Carpathian Basin. [d-Asp3, Mdha7]MC–RR was identified from the blooms sample by MALDI-TOF and NMR. Concentrations of [d-Asp3, Mdha7]MC–RR were measured by capillary electrophoresis to compare the microcystin content of the field samples and the isolated, laboratory-maintained P. rubescens strain. In analyzing the MC gene cluster of the isolated P. rubescens strain, a deletion in the spacer region between mcyE and mcyG and an insertion were located in the spacer region between mcyT and mcyD. The insertion elements were sequenced and partly identified. Although some invasive tropical cyanobacterial species have been given a great deal of attention in many recent studies, our results draw attention to the spread of the alpine organism P. rubescens as a MC-producing, bloom-forming species. PMID:24351711

  7. Beachrock formation in temperate coastlines: Examples in sand-gravel beaches adjacent to the Nerbioi-Ibaizabal Estuary (Bilbao, Bay of Biscay, North of Spain)

    NASA Astrophysics Data System (ADS)

    Arrieta, N.; Goienaga, N.; Martínez-Arkarazo, I.; Murelaga, X.; Baceta, J. I.; Sarmiento, A.; Madariaga, J. M.

    2011-10-01

    Beachrocks are coastal sedimentary formations resulting from a relative rapid cementation of beach sediments by the precipitation of carbonate cements. These lithified structures are not usually observed at temperate settings. The present work is focused on the occurrence of a significant intertidal cementation in sand-gravel beaches formed among 43 °N latitude coastline, close to the Nerbioi-Ibaizabal estuary (Bilbao, Bay of Biscay, North of Spain). Raman micro-spectroscopy combined with SEM-EDX analyses and petrographic descriptions have been applied for the determination of the cement generations and the cemented materials compositions of the beachrock outcrops. In general terms, the cements described were: Cement Generation 1 (CG 1, aragonite, high-magnesium calcite and silicate mixtures), Cement Generation 2 (CG 2, aragonite) and Cement Generation 3 (CG 3, mixtures of CaCO 3 polymorphs and iron oxides). The rest of the interstitial porosity of the rocks appeared either empty or filled with heterogeneous cemented mixtures of previously reworked compounds. The mineralogy, the regular distribution and the isopachous character of the carbonate cements together with the accurate cementation at advanced seaward bands propose a possible marine-phreatic context for the beachrock formation. However, the impure cements and the materials covering the interstitial porosity seem to be the result of both, the weathering actions consequences and the surface alterations of specific grains. Moreover, the presence of modern cemented materials (e.g. slag, bricks and pebbles) suggest a recent formation of the phenomenon.

  8. Modeling three-dimensional flow about ellipsoidal inhomogeneities with application to flow to a gravel-packed well and flow through lens-shaped inhomogeneities

    NASA Astrophysics Data System (ADS)

    Fitts, Charles R.

    1991-05-01

    Analytic functions are superimposed to model three-dimensional steady groundwater flow in regions containing one or more Inhomogeneities shaped like prolate or oblate ellipsoids of revolution. Each function and the sum of such functions are solutions of Laplace's equation, the governing differential equation for steady groundwater flow. The functions are implemented in a manner that provides exact continuity of flow across the entire boundary of each inhomogeneity. In general, continuity of head is provided at specified control points on the boundary and is approximated between control points. For the case of one inhomogeneity in a uniform flow field, it turns out that there is exact continuity of head across the entire surface of the inhomogeneity. The method is implemented in a computer program written by the author. Two applications are demonstrated: (1) flow to a gravel-packed well and (2) flow through a series of lens-shaped inhomogeneities. The examples demonstrate that the approximation of continuity of head can be made acceptable for many problems. A possible application of the technique would be testing various theories regarding contaminant migration and dispersion by simulating flow and chemical diffusion through large numbers of lens-shaped inhomogeneities.

  9. Redox transformations and transport of cesium and iodine (-1, 0, +5) in oxidizing and reducing zones of a sand and gravel aquifer

    USGS Publications Warehouse

    Fox, P.M.; Kent, D.B.; Davis, J.A.

    2010-01-01

    Tracer tests were performed in distinct biogeochemical zones of a sand and gravel aquifer in Cape Cod, MA, to study the redox chemistry (I) and transport (Cs, I) of cesium and iodine in a field setting. Injection of iodide (I -) into an oxic zone of the aquifer resulted in oxidation of I - to molecular iodine (I2) and iodate (IO3-) over transport distances of several meters. Oxidation is attributed to Mn-oxides present in the sediment. Transport of injected IO 3- and Cs+ was retarded in the mildly acidic oxic zone, with retardation factors of 1.6-1.8 for IO3- and 2.3-4.4for Cs. Cs retardation was likely due to cation exchange reactions. Injection of IO3- into a Fe-reducing zone of the aquifer resulted in rapid and complete reduction to I- within 3 m of transport. The nonconservative behavior of Cs and I observed during the tracer tests underscores the necessity of taking the redox chemistry of I as well as sorption properties of I species and Cs into account when predicting transport of radionuclides (e.g., 129I and 137Cs) in the environment.

  10. Improving classification of hydrogeomorphic features in a gravel-bed river using an object-oriented fuzzy classification of multispectral satellite and LiDAR terrain data

    NASA Astrophysics Data System (ADS)

    Aggett, G. R.

    2012-12-01

    Recent attempts to map hydrogeomorphic objects by automatically classifying high spatial and spectral resolution data have tended to yield somewhat unsatisfactory results. This paper suggests that the main reason for this is the inherent limitations of image processing techniques that use a per-pixel approach to spectral classification, and their tendency to ignore spatial characteristics and relationships of hydrogeomorphic objects in the classification process. Pixel-based classifications have problems adequately or conveniently exploiting contextual information or expert knowledge. Object-based image-processing techniques may overcome these difficulties by first segmenting the image into meaningful multi-pixel objects of various sizes, based on both spectral and spatial characteristics of groups of pixels. Objects are assigned classes using fuzzy logic and a hierarchical decision key. This is tested here in the fluvial domain by comparing a per-pixel classification of a gravel-bed river to an object-oriented fuzzy classifier, using a readily available and relatively inexpensive high resolution satellite dataset that can be ordered for a specific date either in the future, or from an image library. Despite improved results using the object-oriented method, we also assert and demonstrate that the fusion of image data with detailed terrain modeled information is required if we are to make strides in reducing classification ambiguities in complex river systems. Thus a second experiment investigates the utility of fusing a LiDAR dataset with multispectral imagery to enhance the object-oriented image classification.

  11. Measurement of the temporal progression of scour in a pool-riffle sequence in a gravel bed stream using an electronic scour monitor

    NASA Astrophysics Data System (ADS)

    Devries, Paul; Burges, Stephen J.; Daigneau, Julie; Stearns, Daniel

    2001-11-01

    A relatively inexpensive prototype monitor was designed and developed to record temporal variation in scour depth and was field-tested in a gravel bed stream. The device consists of plastic practice golf balls that are fitted internally with ring magnets and strung on a two-conductor cable enclosing a small reed switch. The balls are installed and oriented near-vertically in the streambed. As each ball is disturbed and released, it slides along the cable past the reed switch, and the time of circuit closure caused by passage of the magnet is recorded by a data logger. The device can be applied in arrays that span large areas of the streambed, including in wide channels that are inaccessible during a flood. Data obtained from 19 devices installed in an aggrading site described scouring processes in a pool-riffle interface during a bed load transport event. Substantial bed excavation occurred in the region of the pool edge during the rising stage, indicating existence of a local, temporally varying imbalance in bed load transport rate. Bed disturbance in the rest of the site prior to aggradation was limited to the surface and immediate subpavement layer.

  12. 10Be in Quartz Gravel from the Gobi Desert and Evolutionary History of Alluvial Sedimentation in the Ejina Basin, Inner Mongolia, China

    NASA Astrophysics Data System (ADS)

    Lyu, Y.

    2014-12-01

    Reconstructing the evolutionary history of the Gobi deserts developed from alluvial sediments in arid regions has great significance in unraveling changes in both tectonic activity and climate. However, such work is limited by a lack of suitable dating material preserved in the Gobi Desert, but cosmogenic 10Be has great potential to date the Gobi deserts. In the present study, 10Be in quartz gravel from the Gobi deserts of the Ejina Basin in Inner Mongolia of China has been measured to assess exposure ages. Results show that the Gobi Desert in the northern margin of the basin developed 420 ka ago, whereas the Gobi Desert that developed from alluvial plains in the Heihe River drainage basin came about during the last 190 ka. The latter developed gradually northward and eastward to modern terminal lakes of the river. These temporal and spatial variations in the Gobi deserts are a consequence of alluvial processes influenced by Tibetan Plateau uplift and tectonic activities within the Ejina Basin. Possible episodes of Gobi Desert development within the last 420 ka indicate that the advance/retreat of alpine glaciers during glacial/interglacial cycles might have been the dominant factor to influencing the alluvial intensity and water volume in the basin. Intense floods and large water volumes would mainly occur during the short deglacial periods.

  13. Coupling the 3D hydro-morphodynamic model Telemac-3D-sisyphe and seismic measurements to estimate bedload transport rates in a small gravel-bed river.

    NASA Astrophysics Data System (ADS)

    Hostache, Renaud; Krein, Andreas; Barrière, Julien

    2014-05-01

    Coupling the 3D hydro-morphodynamic model Telemac-3D-sisyphe and seismic measurements to estimate bedload transport rates in a small gravel-bed river. Renaud Hostache, Andreas Krein, Julien Barrière During flood events, amounts of river bed material are transported via bedload. This causes problems, like the silting of reservoirs or the disturbance of biological habitats. Some current bedload measuring techniques have limited possibilities for studies in high temporal resolutions. Optical systems are usually not applicable because of high turbidity due to concentrated suspended sediment transported. Sediment traps or bedload samplers yield only summative information on bedload transport with low temporal resolution. An alternative bedload measuring technique is the use of seismological systems installed next to the rivers. The potential advantages are observations in real time and under undisturbed conditions. The study area is a 120 m long reach of River Colpach (21.5 km2), a small gravel bed river in Northern Luxembourg. A combined approach of hydro-climatological observations, hydraulic measurements, sediment sampling, and seismological measurements is used in order to investigate bedload transport phenomena. Information derived from seismic measurements and results from a 3-dimensional hydro-morphodynamic model are exemplarily discussed for a November 2013 flood event. The 3-dimensional hydro-morphodynamic model is based on the Telemac hydroinformatic system. This allows for dynamically coupling a 3D hydrodynamic model (Telemac-3D) and a morphodynamic model (Sisyphe). The coupling is dynamic as these models exchange their information during simulations. This is a main advantage as it allows for taking into account the effects of the morphologic changes of the riverbed on the water hydrodynamic and the bedload processes. The coupled model has been calibrated using time series of gauged water depths and time series of bed material collected sequentially (after

  14. Aggradation of gravels in tidally influenced fluvial systems: Upper Albian (Lower Cretaceous) on the cratonic margin of the North American Western Interior foreland basin

    USGS Publications Warehouse

    Brenner, Richard L.; Ludvigson, Greg A.; Witzke, B.L.; Phillips, P.L.; White, T.S.; Ufnar, David F.; Gonzalez, Luis A.; Joeckel, R.M.; Goettemoeller, A.; Shirk, B.R.

    2003-01-01

    Alluvial conglomerates were widely distributed around the margin of the Early Cretaceous North American Cretaceous Western Interior Seaway (KWIS). Conglomerates, sandstones, and lesser amounts of mudstones of the upper Albian Nishnabotna Member of the Dakota Formation were deposited as fill-in valleys that were incised up to 80 m into upper Paleozoic strata. These paleovalleys extended southwestward across present-day northwestern Iowa into eastern Nebraska. Conglomerate samples from four localities in western Iowa and eastern Nebraska consist mostly of polycrystalline quartz with lesser amounts of microcrystalline (mostly chert), and monocrystalline quartz. Previous studies discovered that some chert pebbles contain Ordovician-Pennsylvanian invertebrate fossils. The chert clasts analyzed in this study were consistent with these findings. In addition, we found that non-chert clasts consist of metaquartzite, strained monocrystalline quartz and 'vein' quartz from probable Proterozic sources, indicating that parts of the fluvial system's sediment load must have travelled distances of 400-1200 km. The relative tectonic stability of this subcontinent dictated that stream gradients were relatively low with estimates ranging from 0.3 to 0.6 m/km. Considering the complex sedimentologic relationships that must have been involved, the ability of low-gradient easterly-sourced rivers to entrain gravel clasts was primarily a function of paleodischarge rather than a function of steep gradients. Oxygen isotopic evidence from Albian sphaerosiderite-bearing paleosols in the Dakota Formation and correlative units from Kansas to Alaska suggest that mid-latitude continental rainfall in the Albian was perhaps twice that of the modern climate system. Hydrologic fluxes may have been related to wet-dry climatic cycles on decade or longer scales that could account for the required water supply flux. Regardless of temporal scale, gravels were transported during 'high-energy' pulses, under

  15. Numerical Model for Channel/Floodplain Exchange on a Gravel Bed River: Relative Importance of Upstream and Downstream Boundaries and of Lateral Exchange (Invited)

    NASA Astrophysics Data System (ADS)

    Lauer, J. W.

    2013-12-01

    The centennial-scale evolution of a meandering gravel-bed river has been represented using a size-specific 1-D sediment transport model. The model differs from other 1-D morphodynamic models for gravel-bed rivers in that it allows for sediment storage in and remobilization from an off-channel sediment storage reservoir representing the floodplain. Hydraulics is represented using a 1-D gradually varied flow model that assumes a rectangular cross-section for the channel zone and a constant elevation for the floodplain. Because the solution for steady uniform flow is necessarily iterative in this framework, the gradually varied hydraulic model is not significantly more computationally intensive than is a normal flow solution. The model is parameterized primarily based on the assumption that the channel creates point bars at a constant elevation above the bed. Bar progradation rate is assumed equal to a specified lateral migration rate (which can vary as a function of sediment load). The return of sediment from floodplain to channel is assumed equal to the lateral migration rate times the average bank elevation. Any net imbalance in sediment storage within the floodplain zone results in a change in average elevation and size distribution for the floodplain. This in turn affects the partition of flow between channel and floodplain and the net flux of sediment from the floodplain to channel, eventually causing the model to evolve toward a steady state bankfull capacity. The model is applied to the Ain River, France, a tributary of the Rhône River. The Ain River underwent significant geomorphic transformations over the course of the 20th century in response to changes in climate, vegetation, floodplain management, and, especially, because of the installation of a series of hydroelectric dams. In general, the channel became more incised and less laterally active during this period. However, bank erosion and sediment deposition in bars and floodplain channels continues to

  16. Combined effects of dam removal and past sediment mining on a relatively large lowland sandy gravel bed river (Vienne River, France)

    NASA Astrophysics Data System (ADS)

    Ursache, Ovidiu; Rodrigues, Stephane; Bouchard, Jean-Pierre; Jugé, Philippe; Richard, Nina

    2014-05-01

    Dam removal is of growing interest for the management of sediment fluxes within fluvial basins, morphological evolution and ecological restoration of rivers. If dam removal experiments are now quite well documented for small streams located in the upstream parts of river networks, examples of lowland and relatively large rivers are still scarce. In this study we present a dam removal operation carried out on the Vienne River (France) to restore both sediment and biotic continuity. The Vienne River is 363 km in length. On its middle reaches the average slope is equal to 0.0003 m.m-1 and the average annual discharge is 195 m3.s-1 at the gauging station of Nouâtre. The river is characterized by a sinuous single channel of an average width of 150 m. The sediments are mainly made of a siliceous mixture of sands and gravels and were intensively mined between years 1930 and 1995's. In 1920, a 4 m height dam was built just downstream the confluence between the Vienne and Creuse Rivers triggering a total sediment deposition upstream of 900 000 m3 in 75 years. Hence, in 1998, the removal of the dam increased severely the sediment supply delivered to the Vienne River. The objective of this study is to understand and quantify the fluvial processes and morphological evolution on a reach of 50 km of the Vienne associated with the dam remova and the presence of ancient sand pits located along the riverbed. This study is based on field data collected during 7 surveys performed between 1998 and 2013. This large dataset focuses on bed geometry (detailed bathymetrical surveys), sediment grain size, and bedload fluxes measured using isokinetic samplers. It was combined with a 1D numerical model developed to assess flow dynamics and sediment transport capacity before and after dam removal. Results show that dam removal triggered both headward and progressive (near the dam) erosions and that discharges higher than 100 m3.s-1 were sufficient to erode the sandy sediments trapped by the

  17. Impact of transient stream flow on water exchange and reactions in the hyporheic zone of an in-stream gravel bar

    NASA Astrophysics Data System (ADS)

    Trauth, Nico; Schmidt, Christian; Fleckenstein, Jan H.

    2015-04-01

    Groundwater-surface water exchange is an important process that can facilitate the degradation of critical substances like nitrogen-species and contaminants, supporting a healthy status of the aquatic ecosystem. In our study, we simulate water exchange, solute transport and reactions within a natural in-stream gravel bar using a coupled surface and subsurface numerical model. Stream water flow is simulated by computational fluid dynamics software that provides hydraulic head distributions at the streambed, which are used as an upper boundary condition for a groundwater model. In the groundwater model water exchange, solute transport, aerobic respiration and denitrification in the subsurface are simulated. Ambient groundwater flow is introduced by lateral upstream and downstream hydraulic head boundaries that generate neutral, losing or gaining stream conditions. Stream water transports dissolved oxygen, organic carbon (as the dominant electron donor) and nitrate into the subsurface, whereas an additional nitrate source exists in the ambient groundwater. Scenarios of stream flow events varying in duration and stream stage are simulated and compared with steady state scenarios with respect to water fluxes, residence times and the solute turn-over rates. Results show, that water exchange and solute turn-over rates highly depend on the interplay between event characteristics and ambient groundwater levels. For scenarios, where the stream flow event shifts the hydraulic system to a net-neutral hydraulic gradient between the average stream stage and the ambient groundwater level (minimal exchange between ground- and surface water), solute consumption is higher, compared to the steady losing or gaining case. In contrast, events that induce strong losing conditions lead to a lower potential of solute consumption.

  18. Linking River Management-Induced Perturbations of Hydrologic and Sediment Regimes to Geomorphic Processes Along a Highly-Dynamic Gravel-Bed River: Snake River, WY.

    NASA Astrophysics Data System (ADS)

    Leonard, C.; Legleiter, C. J.

    2015-12-01

    Encroachment of human development onto river floodplains creates a need to stabilize rivers and provide flood protection. Structural interventions, such as levees, often perturb hydrologic and sediment regimes and thus can initiate morphological responses. An understanding of how human activities affect river morphodynamics and trigger channel change is needed to anticipate future river responses and facilitate effective restoration. This study examines approximately 66 km of the Snake River, WY, USA, and links sediment transport processes to channel form and behavior by developing a morphological sediment budget that spans both a natural, unconfined reach and a reach confined by artificial levees. Sediment transport rates are inferred from the morphological sediment budget and a bed mobility study is used to estimate entrainment thresholds that allow us to link the hydrological regime during the sediment budget period to the observed channel changes. Results indicate that lateral constriction by levees triggers a positive feedback mechanism by incising the bed, focusing flow energy, thus increasing transport capacity, and leading to armoring of the bed. In other systems, armoring promotes widening of the channel but in this case levees prevent widening and the channel instead migrates across the braidplain rapidly, producing further erosion of bars and vegetated islands that is expressed as negative net volumetric changes and increased sediment transport rates. Furthermore, decreased slopes and reduced discharges due to dam regulation in the upstream unconfined reach cause gravel sheets to stall on bars and in other areas of storage, creating a spatial discontinuity in sediment conveyance downstream, and thus contributing to the sediment deficit within the leveed reach.

  19. [Interactive impact of water and nitrogen on yield, quality of watermelon and use of water and nitrogen in gravel-mulched field].

    PubMed

    Du, Shao-ping; Ma, Zhong-ming; Xue, Liang

    2015-12-01

    In order to develop the optimal coupling model of water and nitrogen of watermelon under limited irrigation in gravel-mulched field, a field experiment with split-plot design was conducted to study the effects of supplementary irrigation volume, nitrogen fertilization, and their interactions on the growth, yield, quality and water and nitrogen use efficiency of watermelon with 4 supplementary irrigation levels (W: 0, 35, 70, and 105 m³ · hm⁻²) in main plots and 3 nitrogen fertilization levels (N: 0, 120, and 200 kg N · hm⁻²) in sub-plots. The results showed that the photosynthetic rate, yield, and water and nitrogen use efficiency of watermelon increased with the increasing supplementary irrigation, but the nitrogen partial productivity and nitrogen use efficiency decreased with increasing nitrogen fertilization level. The photosynthetic rate and quality indicators increased with increasing nitrogen fertilization level as the nitrogen rate changed from 0 to 120 kg N · hm⁻², but no further significant increase as the nitrogen rate exceeded 120 kg · hm⁻². The interactive effects between water and nitrogen was significant for yield and water and nitrogen use efficiency of watermelon, supplementary irrigation volume was a key factor for the increase yield compared with the nitrogen fertilizer, and the yield reached the highest for the W₇₀N₂₀₀ and W₁₀₅ N₁₂₀ treatments, for which the yield increased by 42.4% and 40.4% compared to CK. Water use efficiency (WUE) was improved by supplementary irrigation and nitrogen rate, the WUE of all nitrogen fertilizer treatments were more than 26 kg · m⁻³ under supplemental irrigation levels 70 m³ · hm⁻² and 105 m³ · hm⁻². The nitrogen partial productivity and nitrogen use efficiency reached the highest in the treatment of W₁₀₅N₁₂₀. It was considered that under the experimental condition, 105 m³ · hm⁻² of supplementary irrigation plus 120 kg · hm⁻² of nitrogen

  20. Remote measurement of gravel-bed river depths and analysis of the geomorphic response of rivers to canals and small dams

    NASA Astrophysics Data System (ADS)

    Walther, Suzanne Corinna

    This dissertation investigates the potential impacts of canals and small dams on gravel-bed rivers and methods for documenting those impacts. First, I evaluate the potential for mapping channel depths along the McKenzie River, OR, using 10 cm resolution optical aerial imagery with a hydraulically-assisted bathymetry (HAB-2) model. Results demonstrate that channel depths can be accurately mapped in many areas, with some imagery limitations. The HAB-2 model works well in the majority of the river (R2=0.89) when comparing modeled to observed depths, but not in areas of shadow, surface turbulence, or depths >1.5 m. Next, I analyze the relative effects of a small dam and two diversion canals on sediment distribution along bars of the lower McKenzie River. The typical pattern of downstream fining is disrupted at each feature and several tributaries, particularly in the "reduced water reaches" below canal outtakes. Most modeled discharge values necessary to mobilize bar sediments fall at or below the 2-year flood return interval, with the remaining at or below the 5-year flood return interval, generally reflecting the D50 values at each bar (20-115 mm). The third analysis investigates the potential to document geomorphic impacts of small dams in Oregon at ecoregion extents using air photos and publically available data sets. This analysis highlights data disparity with respect to the collecting agency's mission and the difficulty of using remote sensing for small dams. Though the imagery was not useful in evaluating small dam impacts due to resolution and feature size, the data were useful in mapping the small dam distribution across Oregon and each ecoregion. Sixty-one percent of Oregon land is located in the catchment of at least one small dam and the greatest number of dams per area is in the Willamette Valley ecoregion. Overall, this research suggests that, while the application of these techniques must be improved, our ability to observe, study, and understand rivers

  1. Using LIDAR and UAV-derived point clouds to evaluate surface roughness in a gravel-bed braided river (Vénéon river, French Alps)

    NASA Astrophysics Data System (ADS)

    Vázquez Tarrío, Daniel; Borgniet, Laurent; Recking, Alain; Liebault, Frédéric; Vivier, Marie

    2016-04-01

    The present research is focused on the Vénéon river at Plan du Lac (Massif des Ecrins, France), an alpine braided gravel bed stream with a glacio-nival hydrological regime. It drains a catchment area of 316 km2. The present research is focused in a 2.5 km braided reach placed immediately upstream of a small hydropower dam. An airbone LIDAR survey was accomplished in October, 2014 by EDF (the company managing the small hydropower dam), and data coming from this LIDAR survey were available for the present research. Point density of the LIDAR-derived 3D-point cloud was between 20-50 points/m2, with a vertical precision of 2-3 cm over flat surfaces. Moreover, between April and Juin, 2015, we carried out a photogrammetrical campaign based in aerial images taken with an UAV-drone. The UAV-derived point-cloud has a point density of 200-300 points/m2, and a vertical precision over flat control surfaces comparable to that of the LIDAR point cloud (2-3 cm). Simultaneously to the UAV campaign, we took several Wolman samples with the aim of characterizing the grain size distribution of bed sediment. Wolman samples were taken following a geomorphological criterion (unit bars, head/tail of compound bars). Furthermore, some of the Wolman samples were repeated with the aim of defining the uncertainty of our sampling protocol. LIDAR and UAV-derived point clouds were treated in order to check whether both point-clouds were correctly co-aligned. After that, we estimated bed roughness using the detrended standard deviation of heights, in a 40-cm window. For all this data treatment we used CloudCompare. Then, we measured the distribution of roughness in the same geomorphological units where we took the Wolman samples, and we compared with the grain size distributions measured in the field: differences between UAV-point cloud roughness distributions and measured-grain size distribution (~1-2 cm) are in the same order of magnitude of the differences found between the repeated Wolman

  2. Microbial aerobic and anaerobic degradation of acrylamide in sludge and water under environmental conditions--case study in a sand and gravel quarry.

    PubMed

    Guezennec, A G; Michel, C; Ozturk, S; Togola, A; Guzzo, J; Desroche, N

    2015-05-01

    Polyacrylamides (PAMs) are used in sand and gravel quarries as water purification flocculants for recycling process water in a recycling loop system where the flocculants remove fine particles in the form of sludge. The PAM-based flocculants, however, contain residual amounts of acrylamide (AMD) that did not react during the polymerization process. This acrylamide is released into the environment when the sludge is discharged into a settling basin. Here, we explore the microbial diversity and the potential for AMD biodegradation in water and sludge samples collected in a quarry site submitted to low AMD concentrations. The microbial diversity, analyzed by culture-dependent methods and the denaturing gradient gel electrophoresis approach, reveals the presence of Proteobacteria, Cyanobacteria, and Actinobacteria, among which some species are known to have an AMD biodegradation activity. Results also show that the two main parts of the water recycling loop-the washing process and the settling basin-display significantly different bacterial profiles. The exposure time with residual AMD could, thus, be one of the parameters that lead to a selection of specific bacterial species. AMD degradation experiments with 0.5 g L(-1) AMD showed a high potential for biodegradation in all parts of the washing process, except the make-up water. The AMD biodegradation potential in samples collected from the washing process and settling basin was also analyzed taking into account on-site conditions: low (12 °C) and high (25 °C) temperatures reflecting the winter and summer seasons, and AMD concentrations of 50 μg L(-1). Batch tests showed rapid (as little as 18 h) AMD biodegradation under aerobic and anaerobic conditions at both the winter and summer temperatures, although there was a greater lag time before activity started with the AMD biodegradation at 12 °C. This study, thus, demonstrates that bacteria present in sludge and water samples exert an in situ and rapid

  3. Polar gravel beach-ridge systems: Sedimentary architecture, genesis, and implications for climate reconstructions (South Shetland Islands/Western Antarctic Peninsula)

    NASA Astrophysics Data System (ADS)

    Lindhorst, Sebastian; Schutter, Ilona

    2014-09-01

    The sedimentary architecture of polar gravel-beach ridges is presented and it is shown that ridge internal geometries reflect past wave-climate conditions. Ground-penetrating radar (GPR) data obtained along the coasts of Potter Peninsula (King George Island) show that beach ridges unconformably overlie the prograding strand plain. Development of individual ridges is seen to result from multiple storms in periods of increased storm-wave impact on the coast. Strand-plain progradation, by contrast, is the result of swash sedimentation at the beach-face under persistent calm conditions. The sedimentary architecture of beach ridges in sheltered parts of the coast is characterized by seaward-dipping prograding beds, being the result of swash deposition under stormy conditions, or aggrading beds formed by wave overtopping. By contrast, ridges exposed to high-energy waves are composed of seaward- as well as landward-dipping strata, bundled by numerous erosional unconformities. These erosional unconformities are the result of sediment starvation or partial reworking of ridge material during exceptional strong storms. The number of individual ridges which are preserved from a given time interval varies along the coast depending on the morphodynamic setting: sheltered coasts are characterized by numerous small ridges, whereas fewer but larger ridges develop on exposed beaches. The frequency of ridge building ranges from decades in the low-energy settings up to 1600 years under high-energy conditions. Beach ridges in the study area cluster at 9.5, 7.5, 5.5, and below 3.5 m above the present-day storm beach. Based on radiocarbon data, this is interpreted to reflect distinct periods of increased storminess and/or shortened annual sea-ice coverage in the area of the South Shetland Islands for the times around 4.3, c. 3.1, 1.9 ka cal BP, and after 0.65 ka cal BP. Ages further indicate that even ridges at higher elevations can be subject to later reactivation and reworking. A

  4. The abiotic environment of the interstitial of a small Swiss river in the foothills of the Alps and its influence on gravel spawning brown trout (Salmo trutta L.)

    NASA Astrophysics Data System (ADS)

    Schindler, Yael; Michel, Christian; Holm, Patricia; Alewell, Christine

    2010-05-01

    The hyporheic zone can be characterized by multiple abiotic parameters (e.g. bulk density, texture, temperature, oxygen, ammonium, nitrate) which are all influenced directly or indirectly by the exchange processes between surface water and groundwater. These processes can vary both in time and space and are mainly driven by river discharge, ground water level and flow patterns. The input of fine sediment particles can change water-riverbed interactions through river bed clogging potentially affecting the embryonal development and survival of gravel spawning fish, such as brown trout (Salmo trutta L.). With our investigations we aim to understand these complex interactions spatially and temporally on a relevant small scale, i.e. within individual artificial brown trout redds. We designed an experimental field setup to directly investigate i) the influence of the abiotic river and redd environment on brown trout embryo development and ii) the hydrological dynamics affecting the abiotic environment in artificial brown trout. Additionally, our setup allows investigating the temporal dynamics of i) fine-sediment infiltration into the artificial redds and ii) embryo survival to two distinct developmental stages (i.e. eyed stage and hatch) The experiment was conducted in three sites of a typical Swiss river (Enziwigger, Canton of Luzern) with a strongly modified morphology. Individual sites represented a high, medium and low fine-sediment load. In each site, six artificial redds (18 in total) were built and data were collected during the entire incubation phase. Redds were located in places where natural spawning of brown trout is present. We adapted multiple established methods to the smaller scale of our river to study the dynamics of the most relevant abiotic parameters potentially affecting embryo development: Oxygen content and temperature was monitored continuously in different depths, fine sediment (bedload, suspended sediment load and its input in the river bed

  5. Tracing the contribution of debris flow-dominated channels to gravel-bed torrential river channel: implementing pit-tags in the upper Guil River (French Alps)

    NASA Astrophysics Data System (ADS)

    Arnaud-Fassetta, Gilles; Lissak, Candide; Fort, Monique; Bétard, François; Carlier, Benoit; Cossart, Etienne; Madelin, Malika; Viel, Vincent; Charnay, Bérengère; Bletterie, Xavier

    2014-05-01

    In the upper, wider reaches of Alpine valleys, shaping of active channels is usually subject to rapid change. It mostly depends upon hydro-climatic variability, runoff concentration and sediment supply, and may result in alternating sequences of fluvial and debris-flow pulses, as recorded in alluvial fans and terraces. Our study, carried in the frame of SAMCO (ANR) project, focuses on the upper Guil River Valley (Queyras, Southern French Alps) cut into the slaty shale "schistes lustrés". Steep, lower order drains carry a contrasted solid discharge, including predominantly sandy-loam particles mixed with gravels and boulders (sandstone schists, ophiolites). Abundant sediment supply by frost shattering, snow avalanche and landslides is then reworked during snowmelt or summer storm runoff events, and may result in catastrophic, very destructive floods along the main channel, as shown by historical records. Following the RI-30 year 2000 flood, our investigations included sediment budgets, i.e. balance of erosion and deposition, and the mapping of the source, transport and storage of various sediments (talus, colluvium, torrential fans, terraces). To better assess sediment fluxes and sediment delivery into the main channel network, we implemented tracers (pit-tags) in selected sub-catchments, significantly contributing to the sediment yield of the valley bottoms during the floods and/or avalanches: Maloqueste, Combe Morel, Bouchouse and Peyronnelle catchments. The first three are direct tributaries of the Guil River whereas the Peyronnelle is a left bank tributary of the Peynin River, which joins the Guil River via an alluvial cone with high human and material stakes. The Maloqueste and the Combe Morel are two tributaries facing each other in the Guil valley, representing a double lateral constraint for the road during flood events of the Guil River. After pit-tag initialisation in laboratory, we set them up along the four tributaries: Maloqueste (20 pit-tags), Combe

  6. Spatial patterns of groundwater-surface water interactions at the meander-bend scale in a gravel-bed lowland river during a large-scale flow experiment

    NASA Astrophysics Data System (ADS)

    Bray, E. N.; Dunne, T.

    2012-12-01

    Improved characterization of 1) streambed hydraulic conductivity and 2) near-bed and subsurface water temperatures allows better understanding of the spatial patterns of groundwater-surface water exchange in rivers. We measured the effects of a large-scale flow experiment on groundwater-surface water exchange and temperature using fiber optic distributed temperature sensing (DTS), measured temperature in the shallow hyporheic zone (46 cm), and measured streambed saturated hydraulic conductivity (Ksat) over the length of three river meander bends (2 km). Measured channel bed elevation, flow depth, velocity, and bed-material grain size were used to develop a two-dimensional numerical model of the flow field as boundary conditions for a model of the hyporheic flow field. We deployed 2 km of fiber-optic cable directly on top of the riverbed over three pool-riffle sequences each with a different degree of bed mobility. DTS data were collected every 2 m for 32 days (1.5 days at 10 cms, 10 days at 20 cms, 16 days at 10 cms, and 4.5 days at 2-4 cms). Three installations of six hyporheic zone sensors, located near the upstream and downstream ends of the DTS cable, recorded interstitial pore water temperature at depths of 46 cm. During flows of 10 cms, we measured Ksat in the streambed at depths of 60 cm using a groundwater standpipe and backpack permeameter over the length of two meander bends. DTS results showed relatively uniform temperature over the 2-km reach during the initial flow of 10 cms. Near-bed temperatures averaged 15.6°C while pore water temperatures averaged 15.4°C. The 20 cms flow decreased near-bed temperatures to 14.9°C and pore water temperatures averaged 14.7°C. However, during the 20 cms flow, the bed became mobile causing local scour and deposition at three locations and buried the DTS cable with gravel/sand up to 26 cm deep. Our DTS results allowed us to record the transition from near-bed temperatures to shallow subsurface temperatures during a

  7. Geochemical and hydrologic controls on phosphorus transport in a sewage-contaminated sand and gravel aquifer near Ashumet Pond, Cape Cod, Massachusetts

    USGS Publications Warehouse

    Walter, D.A.; Rea, B.A.; Stollenwerk, K.G.; Savoie, Jennifer

    1995-01-01

    The disposal of secondarily treated sewage onto rapid infiltration sand beds at the Massachusetts Military Reservation, Cape Cod, Massachusetts, has created a sewage plume in the underlying sand and gravel aquifer; the part of the\\x11sewage plume that contains dissolved phosphorus extends about 2,500 feet downgradient of the sewage-disposal beds. A part of the plume that\\x11contains nearly 2 milligrams per liter of phosphorus currently (1993) discharges into Ashumet Pond along about 700 feet of shoreline. The sewage plume discharges from about 59 to about 76 kilograms of phosphorus per year into the pond. Hydraulic-head measurements indicate that the north end of Ashumet Pond is a ground-water sink and an increased component of ground-water discharge and phosphorus flux into\\x11the pond occurs at higher water levels. Phosphorus was mobile in ground water in two distinct geochemical environments-an anoxic zone that contains no dissolved oxygen and as much as 25\\x11milligrams per liter of dissolved iron, and a more areally extensive suboxic zone that contains little or no iron, low but detectable dissolved oxygen, and as much as 12 milligrams per liter of dissolved manganese. Dissolved phosphorus is mobile in the suboxic geochemical environment because continued phosphorus loading has filled available sorption sites in the aquifer. Continued disposal of sewage since 1936 has created a large reservoir of sorbed phosphorus that is much greater than the mass of dissolved phosphorus in the ground water; the average ratio of sorbed to dissolved phosphorus in the anoxic and suboxic parts of the sewage plume were 31:1 and 155:1, respectively. Column experiments indicate that phosphorus in the anoxic core of the plume containing dissolved iron may be immobilized within 17 years by sorption and coprecipitation with new iron oxyhydroxides following the cessation of sewage disposal and the introduction of uncontaminated oxygenated ground water into the aquifer in December

  8. Health assessment for Nearshore/Tideflats, Tacoma, Washington, Region 10. CERCLIS No. WAD980726368. Final report

    SciTech Connect

    Not Available

    1988-07-01

    The Commencement Bay Nearshore/Tideflats project site is located in Pierce County, Washington and includes approximately 12 square miles of shallow water, shorelines, tideflats, and upland industrial/commercial sections in and around the City of Tacoma. Since the late 1800s, industrialization of the Commencement Bay area has resulted in many metals, such as lead and arsenic, and organic compounds, such as polychlorinated bipheny (PCBs) and polynuclear aromatic hydrocarbon (PAHs), being released into the marine environment. The waterways and the shoreline are impacted by over 400 potential pollutant sources, including storm drains, pulp mills, chemical plants, and oil refineries. Levels of contaminants in bottom fish and shell fish pose a potential public health concern for those consuming local seafood. Levels of contaminants in sediment, surface water, soil, and air may also pose potential public health concerns for remedial workers and those individuals involved in recreational and commercial activities at the site.

  9. Effects of LiDAR-derived, spatially distributed vegetation roughness on two-dimensional hydraulics in a gravel-cobble river at flows of 0.2 to 20 times bankfull

    NASA Astrophysics Data System (ADS)

    Abu-Aly, T. R.; Pasternack, G. B.; Wyrick, J. R.; Barker, R.; Massa, D.; Johnson, T.

    2014-02-01

    The spatially distributed effects of riparian vegetation on fluvial hydrodynamics during low flows to large floods are poorly documented. Drawing on a LiDAR-derived, meter-scale resolution raster of vegetation canopy height as well as an existing algorithm to spatially distribute stage-dependent channel roughness, this study developed a meter-scale two-dimensional hydrodynamic model of ~ 28.3 km of a gravel/cobble-bed river corridor for flows ranging from 0.2 to 20 times bankfull discharge, with and without spatially distributed vegetation roughness. Results were analyzed to gain insight into stage-dependent and scale-dependent effects of vegetation on velocities, depths, and flow patterns. At the floodplain filling flow of 597.49 m3/s, adding spatially distributed vegetation roughness parameters caused 8.0 and 7.4% increases in wetted area and mean depth, respectively, while mean velocity decreased 17.5%. Vegetation has a strong channelization effect on the flow, increasing the difference between mid-channel and bank velocities. It also diverted flow away from densely vegetated areas. On the floodplain, vegetation stands caused high velocity preferential flow paths that were otherwise unaccounted for in the unvegetated model runs. For the river as a whole, as discharge increases, overall roughness increases as well, contrary to popular conception.

  10. The impact of a dam reservoir-induced base-level rise on mountain river morphology. New insight from the gravel-bed Smolnik River in the Polish Carpathians

    NASA Astrophysics Data System (ADS)

    Liro, Maciej

    2016-04-01

    River reaches upstream from dam reservoirs, where water level fluctuations occur due to backwater effects, may be utilized as a field laboratory of base-level rise effects on river morphology. Here I present the results of the aerial photo-based (1963-2012) reconstruction of the long-term morphological adjustments of the small, gravel-bed Smolnik River in the backwater of the Rożnów Reservoir (1941) (Southern Poland). Channel narrowing and the formation of a relatively stable single-thread, high sinuosity channel with densely vegetated banks were observed in this zone due to forced fine and coarse sediments deposition connected with the backwater effects of the reservoir. This study has shown that specific river morphology may relatively quickly develop in the backwater zones of dam reservoirs as an effect of disturbances in the sediment and water transport connected with the base-level rise. This study also suggests that long-term river morphological adjustments in the backwater seem to be significantly controlled by the dynamic feedback between the fine sediments deposition and vegetation expansion that facilitate the development and maintenance of a single-thread, high sinuosity channel.

  11. Gravel packing feasible in horizontal well completions

    SciTech Connect

    Zaleski, T.E. Jr.; Ashton, J.P. )

    1990-06-11

    Successful completion of horizontal wells in unconsolidated formations depends on proper equipment selection and installation method balanced with reservoir objectives, formation parameters, and costs. The guidelines for designing these completions are based on generalized field experience, including horizontal cases where applicable.

  12. Determining the turnover time of mercury-contaminated fine-grained sediment in the gravel bed of the South River, Virginia using Pb-210, Be-7 and Cs-137

    NASA Astrophysics Data System (ADS)

    Pomraning, S. N.; Pizzuto, J. E.; Jurk, D.

    2010-12-01

    Fine-grained sediment and associated contaminants mediate important geochemical cycles in the hyporheic zone of gravel-bed rivers, but the turnover time of fine particles in these environments has rarely been measured. We analyzed the activities of Pb-210, Cs-137 and Be-7 in samples from four cores obtained on November 2, 2009 from a representative section of the bed composed of a mixture of sand, pebbles, and cobbles. The median grain size is 25.5 mm, the 84th percentile grain diameter is 57.8 mm, and 5.7% of the bed is composed of sediment smaller than 2 mm (sand sized or smaller sediment). The cores were sampled at five centimeter depth increments and each sample was sieved to extract the silt- and clay-sized particles. After freeze-drying the samples, equivalent depth intervals from all the cores were combined to yield a spatially averaged sample with depth intervals of 0-5 cm, 5-10 cm, 10-15 cm, 15-20 cm and 20-25 cm. Radionuclide activities were measured using a Canberra low energy germanium detector (model GL2020R). Activities of Pb-210 at the time of deposition were estimated from suspended sediment samples collected during a high flow event (recurrence interval 0.24 years) that occurred on November 13, 2009. At a depth of 2.5 cm, the Pb-210 dating indicates that the silt-clay fine fraction of the hyporheic zone is 21.3 years old; fine sediment at a depth of 17.5 cm is 29.3 years old. Assuming that the time-averaged bed elevation has not changed over time, and that sediment at depth is periodically removed by scour and subsequently replaced by fill, methods of reservoir theory suggest that the turnover time of silt- and clay-sized particles in the hyporheic zone is about two years. Because deep scour events are apparently relatively rare, approximately 21 years are required to rework 90% of the bed. These results have important implications for contaminant remediation. Even if all ongoing sources of mercury to the South River are removed, several decades

  13. Health assessment for Kaiser Aluminum and Chemical Corporation, Mead, Spokane County, Washington, Region 10. CERCLIS No. WAD000065508. Preliminary report

    SciTech Connect

    Not Available

    1989-04-12

    The 240-acre Kaiser Aluminum Site is on the National Priorities List. The plant was built in 1942 as an aluminum-reduction facility. Concentrations of cyanide (total) in the river range from 0.011 to 1.7 parts per million (ppm) and free cyanide concentrations ranged from non-detected (ND) to 0.58 ppm. Soils on-site are contaminated with cyanide and fluoride; total cyanide levels range from ND to 985 ppm. The site is considered to be of potential public health concern because of the risk to human health caused by the possibility of exposure to hazardous substances via ingestion of contaminated ground water, dermal absorption of contaminants found in the surface soils on-site, and inhalation of and dermal contact with reentrained contaminated dust.

  14. Health assessment for ALCOA (Vancouver Smelter), Vancouver, Clark County, Washington, Region 10. CERCLIS No. WAD009045279. Final report

    SciTech Connect

    Not Available

    1990-05-09

    The ALCOA (also known as Vancouver Smelter) site, located on the northern bank of the Columbia River about 4 miles west of Interstate 5 in Vancouver, Clark County, Washington, has been proposed for the National Priorities List. The site consists of three waste piles containing about 66,000 tons of waste (spent potlinings and alumina insulation) that were deposited on the north bank of the Columbia River by ALCOA between 1973 and 1981. ALCOA has since sold the aluminum smelter to another company, VANALCO. The contaminants detected in the groundwater in the area surrounding the piles include cyanide, fluoride, and trichloroethene (TCE). The ALCOA site is of potential public health concern because humans may be exposed to hazardous substances at concentrations that may result in adverse health effects.

  15. Health assessment for American Lake Gardens, Tacoma, Pierce County, Washington, Region 10. CERCLIS No. WAD980833065. Preliminary report

    SciTech Connect

    Not Available

    1989-01-19

    The American Lake Gardens site is on the National Priorities List. Two areas within the site are the areas of primary contamination; the northeast section's contamination is believed to have come from the closed landfill (now a golf course) on McChord AFB, and the southwest section's contamination from Fort Lewis. Both Fort Lewis and McChord AFB are NPL sites. The environmental contamination on-site consists of trans-1,2-dichloroethylene (530 ppb), trichloroethylene (260 ppb), methylene chloride (38 ppb), tetrachloroethylene (52 ppb), benzene (6 ppb), and 1,1,1-trichloroethane (18 ppb) in ground water. The site is considered to be of potential public health concern because of the risk to human health caused by the possibility of exposure to hazardous substances via ground water (from private wells still in use) and surface water.

  16. Audit of acute asthma management at the Paediatric Emergency Department at Wad Madani Children’s Hospital, Sudan

    PubMed Central

    Ibrahim, Salma M. H.; Haroun, Huda M.; Ali, Hassan M.; Tag Eldeen, Imad Eldeen M.

    2012-01-01

    This audit of hospital care of acute wheeze and asthma aimed to assess the degree of adherence of the acute care of the asthma patients to the published international guidelines. Information was collected in six key areas: patient demographics; initial asthma severity assessment; in-hospital treatment; asthma prophylaxis; asthma education and emergency planning; and follow-up arrangements. The area of initial asthma severity assessment showed defciencies in the clinical measures currently used to verify case severity. In- hospital treatment on the other hand was consistent with recommendations in the use of the inhaled β-2 agonist salbutamol as bronchodilator, the discrete use of aminophylline and the small number of patients ordered chest X-ray. However, the treatment was incoherent with recommendations in the delivery method used for inhaled bronchodilator in relation to the age group of treated patients, absence of ipratropium bromide as a bronchodilator in the management and the large use of antibiotics. Assessment of the areas of asthma prophylaxis, asthma education and emergency- planning and follow-up arrangements illustrated that little efforts were made to assure safe discharge, although these measures have been shown to reduce morbidity after the exacerbation and reduce relapse rates and signifcantly reduce hospitalizations, unscheduled acute visits, missed work days, as well as improving quality of life. This audit emphasizes the need for the adoption of a management protocol for acute asthma care in the emergency department based on published international guidelines and the assurance of its implementation, monitoring and evaluation using the right tools to improve patient care.

  17. The in-situ decontamination of sand and gravel aquifers by chemically enhanced solubilization of multiple-compound DNAPLs with surfactant solutions: Phase 1 -- Laboratory and pilot field-scale testing and Phase 2 -- Solubilization test and partitioning and interwell tracer tests. Final report

    SciTech Connect

    1997-10-24

    Laboratory, numerical simulation, and field studies have been conducted to assess the potential use of micellar-surfactant solutions to solubilize chlorinated solvents contaminating sand and gravel aquifers. Ninety-nine surfactants were screened for their ability to solubilize trichloroethene (TCE), perchloroethylene (PCE), and carbon tetrachloride (CTET). The field test was conducted in the alluvial aquifer which is located 20 to 30 meters beneath a vapor degreasing operation at Paducah Gaseous Diffusion Plant. This aquifer has become contaminated with TCE due to leakage of perhaps 40,000 liters of TCE, which has generated a plume of dissolved TCE extending throughout an area of approximately 3 km{sup 2} in the aquifer. Most of the TCE is believed to be present in the overlying lacustrine deposits and in the aquifer itself as a dense, non-aqueous phase liquid, or DNAPL. The objective of the field test was to assess the efficacy of the surfactant for in situ TCE solubilization. Although the test demonstrated that sorbitan monooleate was unsuitable as a solubilizer in this aquifer, the single-well test was demonstrated to be a viable method for the in situ testing of surfactants or cosolvents prior to proceeding to full-scale remediation.

  18. Effects of local immobile gravel bed elevation on turbulence

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Predicting sand transport over irregular substrates is difficult due to complex interactions of flow, substrate, and sediments. A better understanding of these processes is required to understand the impacts of reservoir flushing and dam removal, which both result in the introduction of finer sedim...