Evidence for aeolian origins of heuweltjies from buried gravel layers

Directory of Open Access Journals (Sweden)

Michael D. Cramer

2016-02-01

Full Text Available Although heuweltjies (19–32 m diameter dominate the surface of much of the southwestern Cape of South Africa, their origins, distribution and age remain controversial. Current hypotheses are that the heuweltjies are (1 constructed by the excavation and mounding habits of burrowing animals; (2 the result of erosion by water of areas between patches protected from fluvial action by denser vegetation or (3 the product of localised aeolian sediment accumulation beneath denser vegetation associated with termitaria. At a site where quartz-containing gravels occur on the soil surface in areas between heuweltjies, these gravels were found to extend as a relatively intact layer of uniform concentration from the inter-mound area into the mound at the same plane as the surrounding soil surface. This buried layer suggests that heuweltjies were either built-up by deposition on a previous soil surface layer or eroded from sediment accumulated above the buried gravel layer. Mounds contain a relatively large proportion of silt consistent with sediment deposition. Mound sediment elemental composition was strongly correlated with that of local shale, indicating a local source of sediment. Pedogenesis was considerably more advanced off- than on-mound. There was no evidence of extensive regional aeolian sediment mantling over the vast area in which the heuweltjies occur. These findings and observations support the aeolian deposition hypothesis of heuweltjie origins combined with a degree of erosion, rather than a termite bioturbation hypothesis or a predominantly erosion-based hypothesis.

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

Science.gov (United States)

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

Gravel Roads: Maintenance and Design Manual

Science.gov (United States)

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

Abrasion-set limits on Himalayan gravel flux.

Science.gov (United States)

Dingle, Elizabeth H; Attal, Mikaël; Sinclair, Hugh D

2017-04-26

Rivers sourced in the Himalayan mountain range carry some of the largest sediment loads on the planet, yet coarse gravel in these rivers vanishes within approximately 10-40 kilometres on entering the Ganga Plain (the part of the North Indian River Plain containing the Ganges River). Understanding the fate of gravel is important for forecasting the response of rivers to large influxes of sediment triggered by earthquakes or storms. Rapid increase in gravel flux and subsequent channel bed aggradation (that is, sediment deposition by a river) following the 1999 Chi-Chi and 2008 Wenchuan earthquakes reduced channel capacity and increased flood inundation. Here we present an analysis of fan geometry, sediment grain size and lithology in the Ganga Basin. We find that the gravel fluxes from rivers draining the central Himalayan mountains, with upstream catchment areas ranging from about 350 to 50,000 square kilometres, are comparable. Our results show that abrasion of gravel during fluvial transport can explain this observation; most of the gravel sourced more than 100 kilometres upstream is converted into sand by the time it reaches the Ganga Plain. These findings indicate that earthquake-induced sediment pulses sourced from the Greater Himalayas, such as that following the 2015 Gorkha earthquake, are unlikely to drive increased gravel aggradation at the mountain front. Instead, we suggest that the sediment influx should result in an elevated sand flux, leading to distinct patterns of aggradation and flood risk in the densely populated, low-relief Ganga Plain.

Shrinkage Properties of Cement Stabilized Gravel

DEFF Research Database (Denmark)

Lund, Mia Schou Møller; Hansen, Kurt Kielsgaard

2014-01-01

Cement stabilized gravel is an attractive material in road construction because its strength prop-erties are accommodating the increasingly higher requirements to the bearing capacity of a base course. However, reflection cracking of cement stabilized gravel is a major concern. In this pa...

Stabilization of gravel deposits using microorganisms

NARCIS (Netherlands)

Van der Star, W.R.L.; Van Wijngaarden, W.K.; Van Paassen, L.A.; Van Baalen, L.R.; Zwieten, G.

2011-01-01

One of the techniques used for the construction of underground infrastructure is horizontal directional drilling (HDD). This trenchless method is complicated when crossing gravel deposits as a borehole in coarse gravel tends to collapse, causing the drill pipe to get stuck or the failure of

Experimental Study of Irregular Waves on a Gravel Beach

Science.gov (United States)

Hu, Nai-Ren; Wu, Yun-Ta; Hwung, Hwung-Hweng; Yang, Ray-Yeng

2017-04-01

In the east coast of Taiwan, the sort grain size more belongs to cobble or gravel, which is physically distinct compared to the sandy beach in the west coast of Taiwan. Although gravel beaches can dissipate more of wave energy, gravel beaches were eroded and coastal road were damaged especially during typhoons. The purpose of this study is to investigate the geomorphological response of gravel beach due to irregular waves. This experiment was carry out in a 21m long, 50 cm wide, 70 cm high wave tank at Tainan Hydraulics Laboratory, National Cheng-Kung University, Taiwan. To simulate of the geometry in the east coast of Taiwan, a physical model with 1/36 scale-down was used, in which the seawall was 10cm built upon a 1:10 slope and gravel grains with D50 being 3.87 mm was nourished in front of the seawall. In terms of typhoon-scale wave condition, irregular waves with scale-down conditions were generated for 600 s for each scenarios and, three different water levels with respect to the gravel beach are designed. Application of laser combined with image processing to produce 3D topographic map, the erosion zone and accretion zone would be found. The resulting morphological change of gravel beach will be measured using an integrated laser and image processing tool to have 3D topographic maps. It is expected to have more understanding about under what conditions the gravel coasts suffer the least damage. In particular, the relation between erosion rates of gravel beach, the angle of gravel slope and the length of the plane on the gravel slope will be achieved

Removal of uranium from gravel using soil washing method

Energy Technology Data Exchange (ETDEWEB)

Kim, Ilgook; Kim, Kye-Nam; Kim, Seung-Soo; Choi, Jong-Won [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-10-15

The development of nuclear technology has led to increasing radioactive waste containing uranium being released and disposed in the nuclear sites. Fine grained soils with a size of less than 4 mm are normally decontaminated using soil washing and electro-kinetic technologies. However, there have been few studies on the decontamination of gravels with a size of more than 4 mm. Therefore, it is necessary to study the decontamination of gravel contaminated with radionuclides. The main objective of the present study on soil washing was to define the optimal condition for acid treatment of uranium-polluted gravel. In this study, soil washing method was applied to remove uranium from gravel. The gravel was crushed and classified as particle sizes. The gravel particles were treated with sulfuric acid in a shaking incubator at 60 .deg. C and 150 rpm for 3 h. The optimal particle size of gravel for soil washing in removal of uranium was between 0.45 and 2.0 mm.

Washing technology development for gravel contaminated with uranium

Energy Technology Data Exchange (ETDEWEB)

Park, Uk Ryang; Kim, Gye Nam; Kim, Seung Soo; Kim, Wan Suk; Moon, Jai Kwon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2013-10-15

The soil washing method has a short decontamination time and is economical. In addition, methods including phytoremediation, solidification/stabilization and bioremediation exist. Phytoremediation and bioremediation are economical, but have low remedial efficiency. In addition, bioremediation causes washing wastewater because it requires a washing process for the separation of microorganisms from the soils. In addition, solidification/stabilization is a commonly used methods, but eventually increases the volume of wastes. As mentioned above, many researches involved in the decontamination of radioactively contaminated soils have been actively processed. On the other hand, researches for decontaminating radioactively contaminated gravels are not being currently processed. In this study, we performed basic experiments using decontamination methods to decontaminate radioactively contaminated gravel. First, we measured the concentration of uranium in gravel included in uranium-contaminated soils and performed a washing experiment to monitor the tendency of uranium removal. In addition, when managing gravel with a low uranium-decontamination rate, we tried to satisfy the radioactivity concentration criteria for self-disposal in the wastes (0.4Bq/g or less) by performing a washing experiment after only a physical crushing process. We performed washing experiments to satisfy the radioactivity concentration criteria for self-disposal (0.4 Bq/g or less) in gravel included in radioactively contaminated soil. We performed washing experiments for gravel whose initial average concentration of uranium was 1.3Bq/g. In addition, the average concentration of uranium was 0.8Bq/g. Too increase the decontamination rate, we crushed the gravel with a jaw crusher and performed the washing experiments. The results were similar to the results without crushing. In addition, it was determined that the smaller the size of the gravel particles, the more efficient the uranium decontamination

Viscoelastic gravel-pack carrier fluid

International Nuclear Information System (INIS)

Nehmer, W.L.

1988-01-01

The ability of a fluid to flow adequately into the formation during gravel-pack treatments is critical to achieving a good pack. Recent studies have indicated ''fish-eyes'' and/or ''microgels'' present in many polymer gelled carrier fluids will plug pore throats, leading to impaired leakoff and causing formation damage. Intensive manipulation of the polymer gelled fluid using shear and filter devices will help remove the particles, but it adds to the cost of the treatment in terms of equipment and manpower. Excessive shear will degrade the polymer leading to poor gravel suspension, while too little shear will cause filtration problems. A gelled carried fluid using a viscoelastic surfactant system has been found to leak off very efficiently to the formation, and cause no formation damage, without the use of shear/filter devices. Viscoelastic surfactant-base gelled fluids develop viscosity because of the association of surfactant moloecules into large rod-shaped aggregates. There is no hydration of polymer involved, so fish-eyes and microgels will not be formed in the viscoelastic fluid. A surfactant-base system having a yield point allows the gravel carrying properties to be much better than fluids gelled with conventional polymer systems (hydroxyethylcellulose [HEC]). For example, a gravel carried fluid gelled with 80 lb HEC/1,000 gal has a viscosity of about 400 cp at 170 sec/sup -1/; a viscoelastic surfactant-base system having only one-half the viscosity still flows into cores about four times more efficiently than the HEC-base fluid. The rheology, leakoff, formation damage and mixing properties of a viscoelastic, surfactant-base, gravel-pack carrier fluid are discussed

Gravel Mobility in a High Sand Content Riverbed

Science.gov (United States)

Haschenburger, J. K.

2017-12-01

In sand-gravel channels, sand may modify gravel transport by changing conditions of entrainment and promoting longer displacements or gravel may inhibit sand transport if concentrated into distinct deposits, which restrict sand supply with consequences for migrating bedform size or form. This study reports on gravel mobility in the lower San Antonio River, Texas, where gravel content in the bed material ranges from about 1% to more than 20%. Sediment transport observations were collected at three U.S. Geological Survey gauging stations by deploying a Helley-Smith sampler with a 0.2 mm mesh bag from which transport rates and mobile grain sizes were determined. The flow rates sampled translate into an annual exceedance expectation from 0.2% to 98%. Gravel transport rates are generally two orders of magnitude smaller than the rates of sand transport. However, the finest gravels are transported at rates on the same order of magnitude as the coarsest sands. At all sites, the 2 and 2.8 mm fractions are transported at the lowest flow rate sampled, suggesting mobility for at least 38% to as much as 98% of the year. Fractions as large as 8 mm are mobilized at flow rates that are expected between 25% and 53% of the year. The largest fractions captured in the sampling (16 to 32 mm) require flows closer to bankfull conditions that occur no more than 0.8% of the year. Results document that some gravel sizes can be frequently transported in low gradient riverbeds with high sand content.

Gravel roads management : volume 2, gravel roads management : implementation guide.

Science.gov (United States)

2011-10-01

This report establishes procedures for managing dirt and gravel roads, with a primary focus on smaller agencies, such as Wyoming counties, that must manage their roads with very limited resources. The report strives, first, to guide and assist smalle...

Gravel roads management : volume 3, gravel roads management : programming guide.

Science.gov (United States)

2010-10-01

This report establishes procedures for managing dirt and gravel roads, with a primary focus on smaller agencies, such as Wyoming counties, that must manage their roads with very limited resources. The report strives, first, to guide and assist smalle...

Experiment on Physical Desalinisation of Uranium-contaminated Gravel Surface

International Nuclear Information System (INIS)

Park, Uk-Ryang; Kim, Gye-Nam; Kim, Seung-Soo; Han, Gyu-Seong; Moon, Jai-Kwon

2014-01-01

As a result, the method to wash uranium-contaminated gravels could not get satisfactory desalinization rate. During the long oxidization process it was judged that uranium penetrated inside the gravels, so we tried to increase the desalinization rate by fragmentizing them into pieces and then washing them. The desalinization rate after fragmentizing the gravels into pieces and washing them brought a satisfactory result.. However, we could obtain desired concentration for gravels with high uranium concentration by fragmentizing them and breaking them further into even smaller pieces. Likewise, desalinization using soil washing process is complicated and has to go through multiple washing steps, resulting in too much of waste fluid generated accordingly. The increase of waste fluid generated leads to the increase in by-products of the final disposal process later on, bringing a not good economic result. Furthermore, taking into account that the desalinization rate is 65% during soil washing process, it is expected that gravel washing will show a similar desalinization result; it is considered uneasy to have a perfect desalinization only by soil washing. The grinding method is actually used in the primary desalinization process in order to desalinize radioactivity-contaminated concrete. This method does desalinization by grinding the radioactivity-contaminated area of the concrete surface with desalinization equipment, which enables a near-to-perfect desalinization for relatively thinly contaminated surface. Likewise, this research verified the degree of desalinization by applying the grinding method and comparing it to the fragmentizing-washing method, and attempted to find a method to desalinize uranium-contaminated gravels more effectively. In order to desalinize uranium-contaminated gravels more effectively and compare to the existing washing-desalinization method, we conducted a desalinization experiment with grinding method that grinds gravel surface. As a

Performance of high-rate gravel-packed oil wells

Energy Technology Data Exchange (ETDEWEB)

Unneland, Trond

2001-05-01

Improved methods for the prediction, evaluation, and monitoring of performance in high-rate cased-hole gravel-packed oil wells are presented in this thesis. The ability to predict well performance prior to the gravel-pack operations, evaluate the results after the operation, and monitor well performance over time has been improved. This lifetime approach to performance analysis of gravel-packed oil wells contributes to increase oil production and field profitability. First, analytical models available for prediction of performance in gravel-packed oil wells are reviewed, with particular emphasis on high-velocity flow effects. From the analysis of field data from three North Sea oil fields, improved and calibrated cased-hole gravel-pack performance prediction models are presented. The recommended model is based on serial flow through formation sand and gravel in the perforation tunnels. In addition, new correlations for high-velocity flow in high-rate gravel-packed oil wells are introduced. Combined, this improves the performance prediction for gravel-packed oil wells, and specific areas can be targeted for optimized well design. Next, limitations in the current methods and alternative methods for evaluation and comparison of well performance are presented. The most widely used parameter, the skin factor, remains a convenient and important parameter. However, using the skin concept in direct comparisons between wells with different reservoir properties may result in misleading or even invalid conclusions. A discussion of the parameters affecting the skin value, with a clarification of limitations, is included. A methodology for evaluation and comparison of gravel-packed well performance is presented, and this includes the use of results from production logs and the use of effective perforation tunnel permeability as a parameter. This contributes to optimized operational procedures from well to well and from field to field. Finally, the data sources available for

McGET: A rapid image-based method to determine the morphological characteristics of gravels on the Gobi desert surface

Science.gov (United States)

Mu, Yue; Wang, Feng; Zheng, Bangyou; Guo, Wei; Feng, Yiming

2018-03-01

The relationship between morphological characteristics (e.g. gravel size, coverage, angularity and orientation) and local geomorphic features (e.g. slope gradient and aspect) of desert has been used to explore the evolution process of Gobi desert. Conventional quantification methods are time-consuming, inefficient and even prove impossible to determine the characteristics of large numbers of gravels. We propose a rapid image-based method to obtain the morphological characteristics of gravels on the Gobi desert surface, which is called the "morphological characteristics gained effectively technique" (McGET). The image of the Gobi desert surface was classified into gravel clusters and background by a machine-learning "classification and regression tree" (CART) algorithm. Then gravel clusters were segmented into individual gravel clasts by separating objects in images using a "watershed segmentation" algorithm. Thirdly, gravel coverage, diameter, aspect ratio and orientation were calculated based on the basic principles of 2D computer graphics. We validated this method with two independent datasets in which the gravel morphological characteristics were obtained from 2728 gravels measured in the field and 7422 gravels measured by manual digitization. Finally, we applied McGET to derive the spatial variation of gravel morphology on the Gobi desert along an alluvial-proluvial fan located in Hami, Xinjiang, China. The validated results show that the mean gravel diameter measured in the field agreed well with that calculated by McGET for large gravels (R2 = 0.89, P < 0.001). Compared to manual digitization, the McGET accuracies for gravel coverage, gravel diameter and aspect ratio were 97%, 83% and 96%, respectively. The orientation distributions calculated were consistent across two different methods. More importantly, McGET significantly shortens the time cost in obtaining gravel morphological characteristics in the field and laboratory. The spatial variation results

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

Science.gov (United States)

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.

Variability of hyporheic exchange in an experimental gravel bed

NARCIS (Netherlands)

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

2011-01-01

A series of tracer experiments in a large outdoor flume were conducted to examine the variability of hyporheic exchange in gravel bed sediments. An 18 m long section of a 2 m wide flume was filled with a 30 cm thick gravel layer with a porosity of 0.39. The gravel of the 17 cm top layer was

Recolonization of gravel habitats on Georges Bank (northwest Atlantic)

Science.gov (United States)

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

Recolonization of gravel habitats on Georges Bank (northwest Atlantic)

Science.gov (United States)

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

Gravel packing dual zones in one trip reduces offshore completion time

International Nuclear Information System (INIS)

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

1991-01-01

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

The Development of Treatment Process Technology for Radioactive Gravel

Energy Technology Data Exchange (ETDEWEB)

Shon, Dong Bin; Kim, Gye Nam; Park, Hye Min; Kim, Ki Hong; Kim, Wan Suk; Lee, Kun Woo; Lee, Ki Won; Moon, Jei Kwon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2011-10-15

The soil washing method holds great promise for the decontamination of contaminated soil as it is very efficient at removal and is time-effective for a great deal of contaminated soils. In addition, this method compensates for a weak point in that is generates a great deal of uranium-contaminated leachate with a short reaction time. Therefore, the soil washing method technology is a good method to remove the initial radioactive substance. The soil dimension compositions consist of clay with small particle sizes, and gravel of larger particle sizes than clay. Also, large gravel creates several problems. Gravel weakens the intensity of the equipment. In addition, intercept soil is discharged in the equipment. And interfere with the pedal recurrence occurs. Therefore, it is necessary to classify the soil. The gravel particle size ranges from 0.5cm to 7.5cm and the granulated gravel particle size ranges from 7.5cm to 20cm. We suppose that the radioactive concentrations are stronger in soil particles larger than the soil particle size (below a 0.5cm diameter). The purpose of this study is to develop a soil washing system for uranium gravel and to define the most suitable operational conditions for the individual elemental equipment in a soil washing system for decontaminating the radioactive gravel from contaminated soil

Sand and Gravel Operations

Data.gov (United States)

Department of Homeland Security — This map layer includes sand and gravel operations in the United States. These data were obtained from information reported voluntarily to the USGS by the aggregate...

A study on the decontamination of the gravels contaminated by uranium

Energy Technology Data Exchange (ETDEWEB)

Park, Ukryang; Kim, Gyenam; Kim, Seungsoo; Moon, Jaikwon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-05-15

The amount of gravels contaminated by uranium is usually about 10% of the contaminated soil. Since such contaminated gravels show different kinds and volumes, it would cost a considerable amount of money if they are to be disposed of without going through any special process. Also, there has not been any particular way or technology for processing the gravels contaminated by uranium. Therefore, various fundamental experiments and researches have been carried out for the decontamination of the gravels contaminated by uranium. Through such experiments and researches, it has been possible to obtain some significant results. The acid cleaning process, which is based on the application of the soil cleaning method, can be regarded as one of the major ways used for decontamination. When the gravels contaminated by uranium are cleaned as they are, most of them tend to show an extremely-low level of decontamination. Therefore, it could be said that the inside of each gravel is also contaminated by uranium. As a result, the gravels contaminated by uranium need to be crushed before being cleaned, which would result in a higher level of efficiency for decontamination compared to the previous way. Therefore, it is more effective to crush the subject gravels before cleaning them in terms of decontamination. However, such test results can only be applied to the gravels contaminated by an average level of uranium concentration. Regarding the gravels showing a higher level of uranium concentration than the average, it is still necessary to carry out more researches. Therefore, this study focused on the level of efficiency for decontamination after the contaminated gravels were crushed before being cleaned, in order to find a way to effectively dispose of the gravels contaminated by high-concentration uranium and secure a high level of efficiency for decontamination. In order to decontaminate the gravels which were contained in the soil contaminated by uranium and showed a higher

The gravel sand transition in a disturbed catchment

Science.gov (United States)

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.

Sand and Gravel Deposits

Data.gov (United States)

Vermont Center for Geographic Information — This dataset is a statewide polygon coverage of sand, gravel, and stone resources. This database includes the best data available from the VT Agency of Natural...

Three-component seismic data in thin interbedded reservoir exploration

Science.gov (United States)

Zhang, Li-Yan; Wang, Yan-Chun; Pei, Jiang-Yun

2015-03-01

We present the first successful application of three-component seismic data to thin interbedded reservoir characterization in the Daqing placanticline of the LMD oilfield. The oilfield has reached the final high water cut stage and the principal problem is how to recognize the boundaries of sand layers that are thicker than 2 m. Conventional interpretation of single PP-wave seismic data results in multiple solutions, whereas the introduction of PS-wave enhances the reliability of interpretation. We analyze the gas reservoir characteristics by joint PP- and PS-waves, and use the amplitude and frequency decomposition attributes to delineate the gas reservoir boundaries because of the minimal effect of fluids on S-wave. We perform joint inversion of PP- and PS-waves to obtain V P/ V S, λρ, and µ ρ and map the lithology changes by using density, λρ, and µ ρ. The 3D-3C attribute λρ slices describe the sand layers distribution, while considering the well log data, and point to favorable region for tapping the remaining oil.

Deposition of Suspended Clay to Open and Sand-Filled Framework Gravel Beds in a Laboratory Flume

Science.gov (United States)

Mooneyham, Christian; Strom, Kyle

2018-01-01

Pulses of fine sediment composed of sand, silt, and clay can be introduced to gravel bed rivers through runoff from burn-impacted hillslopes, landslides, bank failure, or the introduction of reservoir sediment as a result of sluicing or dam decommissioning. Here we present a study aimed at quantifying exchange between suspensions of clay and gravel beds. The questions that motivate the work are: how do bed roughness and pore space characteristics, shear velocity (u∗), and initial concentration (C0) affect clay deposition on or within gravel beds? Where does deposition within these beds occur, and can deposited clay be resuspended while the gravel is immobile? We examine these questions in a laboratory flume using acrylic, open-framework gravel, and armored sand-gravel beds under conditions of varying u∗ and C0. Deposition of clay occurred to all beds (even with Rouse numbers ˜ 0.01). We attribute deposition under full suspension conditions to be an outcome of localized protected zones where clay can settle and available pore space in the bed. For smooth wall cases, protection came from the viscous wall region and the development of bed forms; for the rough beds, protection came from separation zones and low-velocity pore spaces. Bed porosity was the strongest influencer of nondimensional deposition rate; deposition increased with porosity. Deposition was inversely related to u∗ for the acrylic bed runs; no influence of u∗ was found for the porous bed runs. Increases in discharge resulted in resuspension of clay from acrylic beds; no resuspension was observed in the porous bed runs.

Reservoir architecture patterns of sandy gravel braided distributary channel

Directory of Open Access Journals (Sweden)

Senlin Yin

2016-06-01

Full Text Available The purpose of this study was to discuss shape, scale and superimposed types of sandy gravel bodies in sandy-gravel braided distributary channel. Lithofacies analysis, hierarchy bounding surface analysis and subsurface dense well pattern combining with outcrops method were used to examine reservoir architecture patterns of sandy gravel braided distributary channel based on cores, well logging, and outcrops data, and the reservoir architecture patterns of sandy gravel braided distributary channels in different grades have been established. The study shows: (1 The main reservoir architecture elements for sandy gravel braided channel delta are distributary channel and overbank sand, while reservoir flow barrier elements are interchannel and lacustrine mudstone. (2 The compound sand bodies in the sandy gravel braided delta distributary channel take on three shapes: sheet-like distributary channel sand body, interweave strip distributary channel sand body, single strip distributary channel sand body. (3 Identification marks of single distributary channel include: elevation of sand body top, lateral overlaying, “thick-thin-thick” feature of sand bodies, interchannel mudstone and overbank sand between distributary channels and the differences in well log curve shape of sand bodies. (4 Nine lithofacies types were distinguished in distributary channel unit interior, different channel units have different lithofacies association sequence.

Discrete Element Modeling of the Mobilization of Coarse Gravel Beds by Finer Gravel Particles

Science.gov (United States)

Hill, K. M.; Tan, D.

2012-12-01

Recent research has shown that the addition of fine gravel particles to a coarse bed will mobilize the coarser bed, and that the effect is sufficiently strong that a pulse of fine gravel particles can mobilize an impacted coarser bed. Recent flume experiments have demonstrated that the degree of bed mobilization by finer particles is primarily dependent on the particle size ratio of the coarse and fine particles, rather than absolute size of either particle, provided both particles are sufficiently large. However, the mechanism behind the mobilization is not understood. It has previously been proposed that the mechanism is driven by a combination of geometric effects and hydraulic effects. For example, it has been argued that smaller particles fill in gaps along the bed, resulting in a smoother bed over which the larger particles are less likely to be disentrained and a reduced near-bed flow velocity and subsequent increased drag on protruding particles. Altered near-bed turbulence has also been cited as playing an important role. We perform simulations using the discrete element method with one-way fluid-solid coupling to conduct simulations of mobilization of a gravel bed by fine gravel particles. By independently and artificially controlling average and fluctuating velocity profiles, we systematically investigate the relative role that may be played by particle-particle interactions, average near-bed velocity profiles, and near-bed turbulence statistics. The simulations indicate that the relative importance of these mechanisms changes with the degree of mobilization of the bed. For higher bed mobility similar to bed sheets, particle-particle interactions, plays a significant role in an apparent rheology in the bed sheets, not unlike that observed in a dense granular flow of particles of different sizes. For conditions closer to a critical shear stress for bedload transport, the near-bed velocity profiles and turbulence statistics become increasingly important.

Canyon Creek: A late Pleistocene vertebrate locality in interior Alaska

Science.gov (United States)

Weber, Florence R.; Hamilton, Thomas D.; Hopkins, David M.; Repenning, Charles A.; Haas, Herbert

1981-09-01

The Canyon Creek vertebrate-fossil locality is an extensive road cut near Fairbanks that exposes sediments that range in age from early Wisconsin to late Holocene. Tanana River gravel at the base of the section evidently formed during the Delta Glaciation of the north-central Alaska Range. Younger layers and lenses of fluvial sand are interbedded with arkosic gravel from Canyon Creek that contains tephra as well as fossil bones of an interstadial fauna about 40,000 years old. Solifluction deposits containing ventifacts, wedge casts, and rodent burrows formed during a subsequent period of periglacial activity that took place during the maximum phase of Donnelly Glaciation about 25,000-17,000 years ago. Overlying sheets of eolian sand are separated by a 9500-year-old paleosol that may correlate with a phase of early Holocene spruce expansion through central Alaska. The Pleistocene fauna from Canyon Creek consists of rodents (indicated by burrows), Mammuthus primigenius (woolly mammoth), Equus lambei (Yukon wild ass), Camelops hesternus (western camel), Bison sp. cf. B. crassicornis (large-horned bison), Ovis sp. cf. O. dalli (mountain sheep), Canis sp. cf. C. lupus (wolf), Lepus sp. cf. L. othus or L. arcticus (tundra hare), and Rangifer sp. (caribou). This assemblage suggests an open landscape in which trees and tall shrubs were either absent or confined to sheltered and moist sites. Camelops evidently was present in eastern Beringia during the middle Wisconsin interstadial interval but may have disappeared during the following glacial episode. The stratigraphic section at Canyon Creek appears to demonstrate that the Delta Glaciation of the north-central Alaska Range is at least in part of early Wisconsin age and was separated from the succeeding Donnelly Glaciation by an interstadial rather than interglacial episode.

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

Science.gov (United States)

Jacobson, Robert 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.

Compositional Signatures in Acoustic Backscatter Over Vegetated and Unvegetated Mixed Sand-Gravel Riverbeds

Science.gov (United States)

Buscombe, D.; Grams, P. E.; Kaplinski, M. A.

2017-10-01

Multibeam acoustic backscatter has considerable utility for remote characterization of spatially heterogeneous bed sediment composition over vegetated and unvegetated riverbeds of mixed sand and gravel. However, the use of high-frequency, decimeter-resolution acoustic backscatter for sediment classification in shallow water is hampered by significant topographic contamination of the signal. In mixed sand-gravel riverbeds, changes in the abiotic composition of sediment (such as homogeneous sand to homogeneous gravel) tend to occur over larger spatial scales than is characteristic of small-scale bedform topography (ripples, dunes, and bars) or biota (such as vascular plants and periphyton). A two-stage method is proposed to filter out the morphological contributions to acoustic backscatter. First, the residual supragrain-scale topographic effects in acoustic backscatter with small instantaneous insonified areas, caused by ambiguity in the local (beam-to-beam) bed-sonar geometry, are removed. Then, coherent scales between high-resolution topography and backscatter are identified using cospectra, which are used to design a frequency domain filter that decomposes backscatter into the (unwanted) high-pass component associated with bedform topography (ripples, dunes, and sand waves) and vegetation, and the (desired) low-frequency component associated with the composition of sediment patches superimposed on the topography. This process strengthens relationships between backscatter and sediment composition. A probabilistic framework is presented for classifying vegetated and unvegetated substrates based on acoustic backscatter at decimeter resolution. This capability is demonstrated using data collected from diverse settings within a 386 km reach of a canyon river whose bed varies among sand, gravel, cobbles, boulders, and submerged vegetation.

Compositional signatures in acoustic backscatter over vegetated and unvegetated mixed sand-gravel riverbeds

Science.gov (United States)

Buscombe, Daniel; Grams, Paul E.; Kaplinski, Matt A.

2017-01-01

Multibeam acoustic backscatter has considerable utility for remote characterization of spatially heterogeneous bed sediment composition over vegetated and unvegetated riverbeds of mixed sand and gravel. However, the use of high-frequency, decimeter-resolution acoustic backscatter for sediment classification in shallow water is hampered by significant topographic contamination of the signal. In mixed sand-gravel riverbeds, changes in the abiotic composition of sediment (such as homogeneous sand to homogeneous gravel) tend to occur over larger spatial scales than is characteristic of small-scale bedform topography (ripples, dunes, and bars) or biota (such as vascular plants and periphyton). A two-stage method is proposed to filter out the morphological contributions to acoustic backscatter. First, the residual supragrain-scale topographic effects in acoustic backscatter with small instantaneous insonified areas, caused by ambiguity in the local (beam-to-beam) bed-sonar geometry, are removed. Then, coherent scales between high-resolution topography and backscatter are identified using cospectra, which are used to design a frequency domain filter that decomposes backscatter into the (unwanted) high-pass component associated with bedform topography (ripples, dunes, and sand waves) and vegetation, and the (desired) low-frequency component associated with the composition of sediment patches superimposed on the topography. This process strengthens relationships between backscatter and sediment composition. A probabilistic framework is presented for classifying vegetated and unvegetated substrates based on acoustic backscatter at decimeter resolution. This capability is demonstrated using data collected from diverse settings within a 386 km reach of a canyon river whose bed varies among sand, gravel, cobbles, boulders, and submerged vegetation.

The air flow and heat transfer in gravel embankment in permafrost areas

Institute of Scientific and Technical Information of China (English)

JIANG Fan; LIU Shi; WANG Haigang; CHEN Huanzhuo

2004-01-01

A comparative numerical investigation of transient temperature profile and pore-air velocities in horizontal rock block embankments are conducted using the "gravels model", in which the embankment is composed of stones and air, and the "porous media model" respectively. As the velocities from the "gravels model" directly reflect the true flow of air and winter-time convection, in this paper it can be concluded that computational results from the "gravels model"are superior to the "porous media model". In addition, the "gravels model" has the advantages of reflecting the effect of the dimensions and collocation of gravels upon the temperature fields.Therefore, the computation of the gravels embankment is mainly based on the gravels model.Simulation results show that in summer, a clockwise circulation of the pore-air extends throughout most of the embankment. However its motion is very weak that results in relatively straight horizontal isotherm lines. And heat transfer is mainly maintained through conduction. But in winter, the pore-air velocities are higher and multiple vortexes are formed in the embankment.Natural convection then becomes the dominant influence on the isotherm shapes within the embankment. The isotherms are complex and alternative upward and downward flowing plumes exist. The winter-time convection can further reduce the temperature of the foundation soil beneath the gravel embankment. In addition, the effects of the gravel dimensions within the embankment have been analyzed and compared in the gravels model. It shows that in winter, large stones, e.g. 200 mm, lead to stronger vortexes than those of small stones, say 60 mm. Consequently, the zone of low-temperature beneath the large-stone embankment extends deeper into the ground.

Macroinvertebrate Community responses to gravel addition in a Southeastern regulated river

Science.gov (United States)

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

2013-01-01

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

Treatment of Gravel Contaminated with Naturally Occurring Radioactive Element

International Nuclear Information System (INIS)

Sohsah, M. A.; Kamal, S. M.; Mamoon, A.

2004-01-01

Environmental protection primarily means controlling the releases of radioactive and non-radioactive wastes to the environment and involves treatment, storage, cleanup and disposal of these wastes. The present study concerns the cleanup of gravel that has been contaminated with 2 26 R a. Aqueous solutions of different compositions including water and various concentrations of calcium chloride and barium chloride were used to leach the contaminated gravel. The leaching experiments were carried out in glass column. In some leaching experiments, samples of sandy soil were placed below the gravel to test the sorption of the leached 2 26 R a by the soil. The relative efficiencies of the leachant and the extent of sorption of the leached radionuclide were determined both by the liquid scintillation counting and by the thermoluminescent chips. The TLD chips record the dose before and after decontamination of the gravel and before and after contamination of the soil samples when used. The results obtained indicated that acidified barium chloride was relatively the most effective leachant of 2 26 R a contamination. It reduced the dose from the contaminated gravel to almost half. The soil sample used adsorbs the leached radionuclides efficiently, increasing the soil naturally low dose to about six folds

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

Science.gov (United States)

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.

XBeach-G: a tool for predicting gravel barrier response to extreme storm conditions

Science.gov (United States)

Masselink, Gerd; Poate, Tim; McCall, Robert; Roelvink, Dano; Russell, Paul; Davidson, Mark

2014-05-01

Gravel beaches protect low-lying back-barrier regions from flooding during storm events and their importance to society is widely acknowledged. Unfortunately, breaching and extensive storm damage has occurred at many gravel sites and this is likely to increase as a result of sea-level rise and enhanced storminess due to climate change. Limited scientific guidance is currently available to provide beach managers with operational management tools to predict the response of gravel beaches to storms. The New Understanding and Prediction of Storm Impacts on Gravel beaches (NUPSIG) project aims to improve our understanding of storm impacts on gravel coastal environments and to develop a predictive capability by modelling these impacts. The NUPSIG project uses a 5-pronged approach to address its aim: (1) analyse hydrodynamic data collected during a proto-type laboratory experiment on a gravel beach; (2) collect hydrodynamic field data on a gravel beach under a range of conditions, including storm waves with wave heights up to 3 m; (3) measure swash dynamics and beach response on 10 gravel beaches during extreme wave conditions with wave heights in excess of 3 m; (4) use the data collected under 1-3 to develop and validate a numerical model to model hydrodynamics and morphological response of gravel beaches under storm conditions; and (5) develop a tool for end-users, based on the model formulated under (4), for predicting storm response of gravel beaches and barriers. The aim of this presentation is to present the key results of the NUPSIG project and introduce the end-user tool for predicting storm response on gravel beaches. The model is based on the numerical model XBeach, and different forcing scenarios (wave and tides), barrier configurations (dimensions) and sediment characteristics are easily uploaded for model simulations using a Graphics User Interface (GUI). The model can be used to determine the vulnerability of gravel barriers to storm events, but can also be

Leaching of RA-226 contaminated gravel using different aqueous treatments

Energy Technology Data Exchange (ETDEWEB)

Mamoon, A; Abulfaraj, W H; Sohsah, M A [King Abdulaziz University, Jeddah, Saudi Arbabia (Saudi Arabia)

1997-12-31

Investigation of the efficiencies of different aqueous leaching treatments was carried out on gravel artificially contaminated with Ra-226. The extent of leaching efficiency was determined in terms of Ra-226 and its daughter Rn-222. Liquid scintillation counting using high efficiency mineral oil based liquid scintillator was the technique adopted for measuring Ra-226 and Rn-222 leached off the contaminated gravel. Water, dilute solutions of barium chloride and HCl were used as leachants. Different masses of gravel were leached with 200 mL of leachant for various contact time periods. The leached Rn-222 activity measured was plotted vs the decay factor e; from which Rn-222 and Ra-226 originally present in the sample were determined. Several leaching parameters were tested; namely type of leachant, leachant volume/gravel mass ratio, leachant contact time, effect of varying Ba Cl{sub 2} concentration, and successive leaching. Optimization of the leaching parameters for desorption of Ra-226 off the contaminated gravel under laboratory conditions may help determine the ideal conditions for remediating soil contaminated with radium or chemically similar radionuclides. 7 figs.

Gravel road stabilisation of Ehnsjoevaegen, Hallstavik[Using fly ash]; Skogsbilvaegsrenovering av Ehnsjoevaegen, Hallstavik

Energy Technology Data Exchange (ETDEWEB)

Macsik, Josef; Svedberg, Bo [Ecoloop, Stockholm (Sweden)

2006-03-15

Fly ash in geotechnical applications has stabilising, isolating, low permeability and hardening effect. Fly ash can be used in road constructions with low bearing capacity, as well as on top cover material on landfills. The aim of the project was to build a road section with fly ash stabilised gravel, based on laboratory studies, and follow up technical and environmental aspect during the first year after stabilisation. The overall aim of this project was to evaluate fly ash from Holmen Paper, Hallstavik, from technical and environmental point of view in a gravel road construction. A gravel road, Ehnsjoevaegen, was stabilised with fly ash during autumn 2004. This road was a low priority road. The fly ash stabilised road section was 1300 m long. Gravel from the road Ehnsjoevaegen was stabilised and investigated in a laboratory study. Leachability of metals and geotechnical aspects were investigated. The laboratory study showed that fly ash stabilised gravel has high shear strength, however its thawing resistance is not fully acceptable. Additives of cement or merit are needed in order to increase its thawing resistance. The actual road section is not going to be used during thawing period and no additives were used. The test road is divided into different sections including a reference section. The road stabilisation work was conducted with gravel transported to Ehnsjoevaegen from off site and not with gravel from the site. Fly ash was tipped off on a levelled road, followed by tipping of gravel. Mixing fly ash and gravel was done on site by a road scraper. After the mixing the road was gravelled with 0,1 m graded gravel. In this project the fly ash had low water content. In order to get optimal compaction water was added from a tanker supplying water before compacted with a compactor. Results from the pilot test shows that fly ash stabilised gravel can be tipped, mixed and compacted effectively. Tipping can be optimised if fly ash and gravel is mixed in a mixer

Gravel Image Segmentation in Noisy Background Based on Partial Entropy Method

Institute of Scientific and Technical Information of China (English)

无

2000-01-01

Because of wide variation in gray levels and particle dimensions and the presence of many small gravel objects in the background, as well as corrupting the image by noise, it is difficult o segment gravel objects. In this paper, we develop a partial entropy method and succeed to realize gravel objects segmentation. We give entropy principles and fur calculation methods. Moreover, we use minimum entropy error automaticly to select a threshold to segment image. We introduce the filter method using mathematical morphology. The segment experiments are performed by using different window dimensions for a group of gravel image and demonstrates that this method has high segmentation rate and low noise sensitivity.

Ecological Effects of Re-introduction of Salmonid Spawning Gravel in Lowland Danish Streams

DEFF Research Database (Denmark)

Pedersen, Morten Lauge; Kristensen, Esben Astrup; Kronvang, Brian

2009-01-01

recently been conducted in many streams and rivers. However, systematic monitoring of these spawning gravel restoration projects is limited. The overall aim of this paper was to evaluate gravel reintroduction as a long-term salmonid rehabilitation method in 32 lowland streams. Displacement of gravel......, including both restored reaches and upstream control reaches. Downstream displacement of gravel was most common at sites where gravel was reintroduced without further improvement, although these sites exhibited the highest density of YOY brown trout (Salmo trutta), evidencing that the remaining gravel...... is still functional. The intensive study of three streams showed that spawning was enhanced by the introduction of spawning gravel at the restored sites compared to control sites and that habitat quality generally were improved. Our results also suggest complex interactions exist between spawning activity...

Fly ash stabilisation of gravel roads; Flygaska som foerstaerkningslager i grusvaeg

Energy Technology Data Exchange (ETDEWEB)

Macsik, Josef

2006-01-15

Majority of the existing gravel roads have low bearing capacity during spring and autumn, due to thaw and/or rain. Low bearing capacity leads often to bad road conditions. This situation results in higher costs for the lumber industry and the public. Management of gravel roads all the year around would traditionally require excavation of frost susceptible soils and replacement with natural materials. Fly ash (from bio fuels) has good technical properties as bearing layer in road constructions. Fly ash stabilised gravel roads have better function and longer life span with less maintenance than traditional gravel roads. The aim of this project is to show how fly ash stabilisation of gravel roads can increase bearing capacity and what its environmental impact is. The overall aim is to make it easier for entrepreneurs and consulting companies to use fly ash during gravel road renovation and/or constructing new gravel roads. This report targets fly ash producers and road constructors as well as environmental agencies. Two different pilot tests were investigated in this study, Norberg with fly ash from Stora Enso Fors AB, and Boerje (Uppsala) with fly ash from Vattenfall Uppsala AB. Both road sections with related reference section were investigated during a two year period. Only fly ash was used in the bearing layer at Norberg and fly ash gravel was used at Boerje. Bearing capacity was investigated twice, for both locations, November 2003 one month after the road renovation and during thawing, April 2004. Water samples from lysimeters, ground water and surface water were only collected and analysed from Norberg. Experience from the fly ash stabilised road sections show that curing and traffic load can with time compensate for less compaction. The same is noticed at Boerje, although deflection measurements show that there are small differences. Stabilisation of gravel roads increases the roads bearing capacity. Two years after stabilisation 90 timber loads were

Gravel addition as a habitat restoration technique for tailwaters

Science.gov (United States)

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

2010-01-01

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

Liquid filtration properties in gravel foundation of railroad tracks

International Nuclear Information System (INIS)

Strelkov, A; Teplykh, S; Bukhman, N

2016-01-01

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

Impact of recycled gravel obtained from low or medium concrete grade on concrete properties

Directory of Open Access Journals (Sweden)

Yasser Abdelghany Fawzy

2018-04-01

Full Text Available This paper investigates the effect of recycled gravel obtained from low (Gl or medium (Gm concrete grade on fresh property of concrete (slump, mechanical properties (compressive-splitting tensile strength and mass transport properties (ISAT-sorptivity of concrete containing dolomite as a natural coarse aggregate. Concrete specimens were prepared with cement, water, sand and dolomite admixed with recycled gravel. The percentage of recycled gravel/dolomite was 0:100, 25:75, 50:50 and 75:25 at w/c = 0.50, 0.55 and 0.60. The effect of silica fume and bonding admixture at w/c = 0.55 on concrete properties were also considered. The results indicated that, increasing the percentage of recycled gravel/dolomite led to decreasing the slump. All mechanical properties of concrete discussed were inversely affected by increasing percentage of recycled gravel/dolomite from low and medium concrete. Adding 10% SF or bonding admixture increased the mechanical properties of concrete. Mass transport properties of concrete (ISAT-sorptivity were enhanced by decreasing the percentage of recycled gravel/dolomite. The optimum percentage of recycled gravel/dolomite = 25%. Keywords: Recycled gravel, Concrete, Silica fume, Compressive strength, Mass transport

Economic Valuation of Sand and Gravel in Davao del Norte, Philippines

OpenAIRE

Tamayo, Adrian; Tagalo, Romulo

2016-01-01

The study aims to quantify the economic value of the sand and gravel which is deemed as a non-renewable resource. A survey was conducted to extract the consumer surplus of the households, also construct the demand equation for the resource. With the demand equation for sand and gravel at , the consumer surplus was estimated at P8271. Using the economic valuation technique, the economic value of sand and gravel was estimated at P729,568,368. Thus, a very high value imputed on the environmenta...

Thermal remediation of tar-contaminated soil and oil-contaminated gravel

International Nuclear Information System (INIS)

Anthony, E.J.; Wang, J.

2005-01-01

High temperature treatments are commonly considered for the decontamination of soil as they have the advantages of reliability, high capacity, and effective destruction of hazardous materials with reduced long-term liability. This paper examined the remediation of soil contaminated by coal tar as well as gravel contaminated by oil. Pilot plant studies were conducted using 2 representative incineration technologies: rotary kiln and fluidized bed. The coal tar contaminated soil had accumulated over a few decades at a calcination plant in western Canada. The soil was sticky and could not be handled by conventional feeding and combustion systems. Crushed lignite was mixed with the soil as an auxiliary fuel and to reduce stickiness. A pilot plant furnace was used to evaluate the potential of decontamination in a rotary calciner. An analysis of both a modelling study and the test results showed that complete decontamination could be achieved in the targeted calciner. The results suggested that energy recovery was also possible, which could in turn make the remediation process more cost-effective. Decontamination of oil-contaminated gravel was conducted with a pilot plant fluidized bed combustor to study the feasibility of using incineration technology in the remediation of gravel and debris contaminated by oil spills. Results indicated that the gravel was decontaminated with acceptable emission performance. It was concluded that the study will be valuable to the application of commercial incineration processes for the remediation of polluted soils. It was observed that the weathering of the oiled gravel lowered the rate of decontamination. A small amount of salt water resulted in lowered decontamination rates, which may be an important factor for situations involving the remediation of shoreline gravel contaminated by oil. 24 refs., 6 tabs., 7 figs

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

Energy Technology Data Exchange (ETDEWEB)

McManamay, Ryan A [ORNL; Orth, Dr. Donald J [Virginia Polytechnic Institute and State University; Dolloff, Dr. Charles A [United States Department of Agriculture (USDA), United States Forest Service (USFS) and Virginia Pol

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.

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

Science.gov (United States)

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

Effects of gravel mulch on emergence of galleta grass seedlings

International Nuclear Information System (INIS)

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 ampersand 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

Design and maintenance of subsurface gravel wetlands.

Science.gov (United States)

2015-02-01

This report summarizes the University of New Hampshire Stormwater Center (UNHSC) evaluation of : a review of Subsurface Gravel Wetlands design and specifications used by the New Hampshire : Department of Transportation (NHDOT or Department). : Subsur...

Noise Exposure and Hearing Loss Among Sand and Gravel Miners

OpenAIRE

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

2004-01-01

The objectives of this study were to describe workplace noise exposures, risk factors for hearing loss, and hearing levels among sand and gravel miners, and to determine whether full shift noise exposures resulted in changes in hearing thresholds from baseline values. Sand and gravel miners (n = 317) were interviewed regarding medical history, leisure-time and occupational noise exposure, other occupational exposures, and use of hearing protection. Audiometric tests were performed both before...

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

Science.gov (United States)

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

Coupling fine particle and bedload transport in gravel-bedded streams

Science.gov (United States)

Park, Jungsu; Hunt, James R.

2017-09-01

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

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

Science.gov (United States)

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

2015-03-01

While cohesive sediment generally represents a small fraction (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.

Measurement of earthquake-induced shear strain in sandy gravel

International Nuclear Information System (INIS)

Ohkawa, I.; Futaki, M.; Yamanouchi, H.

1989-01-01

The nuclear power reactor buildings have been constructed on the hard rock ground formed in or before the Tertiary in Japan. This is mainly because the nuclear reactor building is much heavier than the common buildings and requires a large bearing capacity of the underlying soil deposit, and additionally the excessive deformation in soil deposit might cause damage in reactor building and subsequently cause the malfunction of the internal important facilities. Another reason is that the Quaternary soil deposit is not fully known with respect to its dynamic property. The gravel, and the sandy gravel, the representative soils of the Quaternary, have been believed to be suitable soil deposits to support the foundation of a common building, although the soils have rarely been investigated so closely on their physical properties quantitatively. In this paper, the dynamic deformability, i.e., the shear stress-strain relationship of the Quaternary diluvial soil deposit is examined through the earthquake ground motion measurement using accelerometers, pore-pressure meters, the specific devices developed in this research work. The objective soil deposit in this research is the sandy gravel of the diluvial and the alluvial

Efficiency of Cleanup of Ra-226 Contaminated Gravel Assayed by LSC and TL Dosimetry

International Nuclear Information System (INIS)

Mamoon, A.; Abulfaraj, W.H.; Kamal, S.M.; Sohsah, M.A.

1999-01-01

The present study concerns itself with decontamination of gravel that had been contaminated with Ra-226 from natural origins. Aqueous solutions of different compositions including water, and various concentrations of CaCl 2 and BaCl 2 were used to leach the contaminated gravel. The leaching experiments were carried out in glass columns. In some leaching experiments a sample of a common brand of sandy soil (fine sand with traces of silt )was placed below the gravel to test the binding capacity (sorption) of this soil for the leached Ra-226

Resistivity profiling for mapping gravel layers that may control contaminant migration at the Amargosa Desert Research Site, Nevada

Science.gov (United States)

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

2008-01-01

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

A Visual Basic program to classify sediments based on gravel-sand-silt-clay ratios

Science.gov (United States)

Poppe, L.J.; Eliason, A.H.; Hastings, M.E.

2003-01-01

Nomenclature describing size distributions is important to geologists because grain size is the most basic attribute of sediments. Traditionally, geologists have divided sediments into four size fractions that include gravel, sand, silt, and clay, and classified these sediments based on ratios of the various proportions of the fractions. Definitions of these fractions have long been standardized to the grade scale described by Wentworth (1922), and two main classification schemes have been adopted to describe the approximate relationship between the size fractions.Specifically, according to the Wentworth grade scale gravel-sized particles have a nominal diameter of ⩾2.0 mm; sand-sized particles have nominal diameters from <2.0 mm to ⩾62.5 μm; silt-sized particles have nominal diameters from <62.5 to ⩾4.0 μm; and clay is <4.0 μm. As for sediment classification, most sedimentologists use one of the systems described either by Shepard (1954) or Folk (1954, 1974). The original scheme devised by Shepard (1954) utilized a single ternary diagram with sand, silt, and clay in the corners to graphically show the relative proportions among these three grades within a sample. This scheme, however, does not allow for sediments with significant amounts of gravel. Therefore, Shepard's classification scheme (Fig. 1) was subsequently modified by the addition of a second ternary diagram to account for the gravel fraction (Schlee, 1973). The system devised by Folk (1954, 1974) is also based on two triangular diagrams (Fig. 2), but it has 23 major categories, and uses the term mud (defined as silt plus clay). The patterns within the triangles of both systems differ, as does the emphasis placed on gravel. For example, in the system described by Shepard, gravelly sediments have more than 10% gravel; in Folk's system, slightly gravelly sediments have as little as 0.01% gravel. Folk's classification scheme stresses gravel because its concentration is a function of

Development of practical decontamination process for the removal of uranium from gravel.

Science.gov (United States)

Kim, Ilgook; Kim, Gye-Nam; Kim, Seung-Soo; Choi, Jong-Won

2018-01-01

In this study, a practical decontamination process was developed to remove uranium from gravel using a soil washing method. The effects of critical parameters including particle size, H 2 SO 4 concentration, temperature, and reaction time on uranium removal were evaluated. The optimal condition for two-stage washing of gravel was found to be particle size of 1-2 mm, 1.0 M H 2 SO 4 , temperature of 60°C, and reaction time of 3 h, which satisfied the required uranium concentration for self-disposal. Furthermore, most of the extracted uranium was removed from the waste solution by precipitation, implying that the treated solution can be reused as washing solution. These results clearly demonstrated that our proposed process can be indeed a practical technique to decontaminate uranium-polluted gravel.

Incipient motion of gravel and coal beds

Indian Academy of Sciences (India)

R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

2. 1Department of Civil Engineering, Indian Institute of Technology, ... the particle size distribution curve following the relationship by Christensen .... where f = friction factor, ρ = mass density of fluid, and V = mean velocity of flow. .... for the incipient motion of gravel and coal beds have been represented by simple empirical.

The Grain-size Patchiness of Braided Gravel-Bed Streams - example of the Urumqi River (northeast Tian Shan, China)

Science.gov (United States)

Guerit, L.; Barrier, L.; Narteau, C.; Métivier, F.; Liu, Y.; Lajeunesse, E.; Gayer, E.; Meunier, P.; Malverti, L.; Ye, B.

2014-02-01

In gravel-bed rivers, sediments are often sorted into patches of different grain-sizes, but in braided streams, the link between this sorting and the channel morpho-sedimentary elements is still unclear. In this study, the size of the bed sediment in the shallow braided gravel-bed Urumqi River is characterized by surface-count and volumetric sampling methods. Three morpho-sedimentary elements are identified in the active threads of the river: chutes at flow constrictions, which pass downstream to anabranches and bars at flow expansions. The surface and surface-layer grain-size distributions of these three elements show that they correspond to only two kinds of grain-size patches: (1) coarse-grained chutes, coarser than the bulk river bed, and (2) finer-grained anabranches and bars, consistent with the bulk river bed. In cross-section, the chute patches are composed of one coarse-grained top layer, which can be interpreted as a local armour layer overlying finer deposits. In contrast, the grain size of the bar-anabranch patches is finer and much more homogeneous in depth than the chute patches. Those patches, which are features of lateral and vertical sorting associated to the transport dynamics that build braided patterns, may be typical of active threads in shallow gravel-bed rivers and should be considered in future works on sorting processes and their geomorphologic and stratigraphic results.

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

Science.gov (United States)

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

2014-12-01

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

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

Science.gov (United States)

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.

Distribution and stability of potential salmonid spawning gravels in steep boulder-bed streams of the eastern Sierra Nevada

International Nuclear Information System (INIS)

Kondolf, G.M.; Cada, G.F.; Sale, M.J.; Felando, T.

1991-01-01

Interest in small hydroelectric development (< 5 MW) has recently focused attention on steep streams and the resident trout populations they contain. High-gradient boulder-bed streams have been the sites of relatively few studies of salmonid spawning habitat, although they have geomorphic and hydraulic characteristics - and therefore gravel distributions - that are quite different from the more commonly described lower-gradient channels. The authors documented gravel distribution in seven high-gradient stream reaches in the eastern Sierra Nevada. Gravels occurred only in locations characterized by relatively low shear stress; they formed small pockets in sites of low divergence and larger deposits upstream of natural hydraulic controls. In 1986 (a wet year), all tracer gravels placed in gravel pockets at nine sites on four streams were completely swept away, and substantial scour, fill, and other channel changes occurred at many sites. In 1987 (a dry year), tracer gravels and the channel cross sections were generally stable. Periodic mobility of gravel may explain why brown trout Salmo trutta are more abundant than rainbow trout Oncorhychus mykiss in the study reaches, where high flows occur every May and June during snowmelt. Brown trout are fall spawners, and their fry emerge long before the high snowmelt flows, whereas rainbow trout are spring spawners whose eggs are in the gravel, and thus vulnerable to scour, during snowmelt flows

Land Use and River Degradation Impact of Sand and Gravel Mining

Science.gov (United States)

Syah, Putra Rizal Ichsan; Hartuti, Purnaweni

2018-02-01

Sand and gravel mining is aimed at providing materials for infrastructure development, as well as providing economical source to the miners. However, the impacts of sand and gravel mining could also cause disturbances to ecological balance, since it is closely related to land use change and river degradation, besides causing conflicts in the miners, the government, and the private relationship. Therefore the government regulation and proper supervision are needed to preserve the ecological balance and decreasing the negative impacts of this mining, and therefore guarantee sustainable development.

Image analysis to measure sorting and stratification applied to sand-gravel experiments

OpenAIRE

Orrú, C.

2016-01-01

The main objective of this project is to develop new measuring techniques for providing detailed data on sediment sorting suitable for sand-gravel laboratory experiments. Such data will be of aid in obtaining new insights on sorting mechanisms and improving prediction capabilities of morphodynamic models. Two measuring techniques have been developed. The first technique is aimed at measuring the size stratification of a sand-gravel deposit through combining image analysis and a sediment remov...

Comparison of different forms of gravel as aggregate in concrete

Directory of Open Access Journals (Sweden)

Sikiru ORITOLA

2014-11-01

Full Text Available Gradation plays an important role in the workability, segregation, and pump ability of concrete. Uniformly distributed aggregates require less paste which will also decrease bleeding, creep and shrinkage while producing better workability, more durable concrete and higher packing. This attempt looks at the effect of particle size distribution pattern for five types of gravel aggregate forms, angular, elongated, smooth rounded, irregular and flaky as related to the strength of concrete produced. Different forms of naturally existing gravel aggregate were collected from a particular location and tests were carried out on them to determine their gradation. Based on the gradation the aggregates were used to prepare different samples of grade 20 concrete with water-cement ratio of 0.5. The particle size distribution resulted in coefficients of uniformity ranging from 1.24 to 1.44. The granite aggregate, which serves as a reference, had a coefficient of uniformity of 1.47. Tests were conducted on fresh and hardened concrete cube samples. The concrete sample CT5 recorded a slump of 32mm and highest compressive strength value of 21.7 N/mm2, among the concrete produced from different forms of gravel.

Triaxial shear behavior of a cement-treated sand–gravel mixture

Directory of Open Access Journals (Sweden)

Younes Amini

2014-10-01

Full Text Available A number of parameters, e.g. cement content, cement type, relative density, and grain size distribution, can influence the mechanical behaviors of cemented soils. In the present study, a series of conventional triaxial compression tests were conducted on a cemented poorly graded sand–gravel mixture containing 30% gravel and 70% sand in both consolidated drained and undrained conditions. Portland cement used as the cementing agent was added to the soil at 0%, 1%, 2%, and 3% (dry weight of sand–gravel mixture. Samples were prepared at 70% relative density and tested at confining pressures of 50 kPa, 100 kPa, and 150 kPa. Comparison of the results with other studies on well graded gravely sands indicated more dilation or negative pore pressure in poorly graded samples. Undrained failure envelopes determined using zero Skempton's pore pressure coefficient (A¯=0 criterion were consistent with the drained ones. Energy absorption potential was higher in drained condition than undrained condition, suggesting that more energy was required to induce deformation in cemented soil under drained state. Energy absorption increased with increase in cement content under both drained and undrained conditions.

Fabrication of gravel for concrete in brown-coal mining. The gravel works at Inden; Betonkiesherstellung im Braunkohlentagebau - Das Kieswerk Inden

Energy Technology Data Exchange (ETDEWEB)

Bertrams, H.J. [Rheinbraun AG, Abt. Tagebau- und Landschaftsplanung, Koeln (Germany)

1995-01-01

The brown-coal open-pit mine is operated by Rheinbraun AG, a Cologne-based company. The mining process offers the possibility to separate gravel and sand from the overburden for marketing, unless they are indispensable for reclaiming the open-pit mine. This combination of raw material production particularly prevents additional landscape consumption by separate gravel dredging and spares the population of an overproportionately densely populated region further inconveniences. Moreover, it helps to save resources. (orig./MSK) [Deutsch] Die Braunkohlengewinnung erfolgt durch die in Koeln ansaessige Rheinbraun AG in Tagebauen. Dabei ergibt sich die Moeglichkeit, im Abraum befindliche Kiese und Sande auszusortieren und dem Markt zuzufuehren, soweit sie nicht zwingend zur Wiedernutzbarmachung des Tagebaus verwendet werden muessen. Durch die Buendelung der Rohstoffgewinnung wird insbesondere der Landschaftsverbrauch durch gesonderte Abgrabungen ausserhalb des Tagebaus und damit verbundene Belastungen der Bevoelkerung in einer ueberdurchschnittlich dicht besiedelten Region verringert. Sie traegt ebenfalls zur Ressourcenschonung bei. (orig./MSK)

STRUCTURE, GROWTH AND MORPHOLOGY OF FISH POPULATIONS FROM GRAVEL-PIT VUKOVINA

Directory of Open Access Journals (Sweden)

Ivan Jakovlić

2001-12-01

Full Text Available After the structure of fish populations from gravel-pit Vukovina was determined, those populations were checked for 10 morphometric and 4 meristic parameters, as well as for length-mass relationship. For chub (Leuciscus cephalus and pumpkinseed (Lepomis gibbosus some meristic characters expressed the values beyond those mentioned in the standard key for the freshwater fish species determination. When compared to other locations, length-mass relationship and condition factor (CF were significantly lower for all checked populations. This indicates that gravel-pit Vukovina is extremely oligotrophic and has very poor fish production.

Delineation of gravel-bed clusters via factorial kriging

Science.gov (United States)

Wu, Fu-Chun; Wang, Chi-Kuei; Huang, Guo-Hao

2018-05-01

Gravel-bed clusters are the most prevalent microforms that affect local flows and sediment transport. A growing consensus is that the practice of cluster delineation should be based primarily on bed topography rather than grain sizes. Here we present a novel approach for cluster delineation using patch-scale high-resolution digital elevation models (DEMs). We use a geostatistical interpolation method, i.e., factorial kriging, to decompose the short- and long-range (grain- and microform-scale) DEMs. The required parameters are determined directly from the scales of the nested variograms. The short-range DEM exhibits a flat bed topography, yet individual grains are sharply outlined, making the short-range DEM a useful aid for grain segmentation. The long-range DEM exhibits a smoother topography than the original full DEM, yet groupings of particles emerge as small-scale bedforms, making the contour percentile levels of the long-range DEM a useful tool for cluster identification. Individual clusters are delineated using the segmented grains and identified clusters via a range of contour percentile levels. Our results reveal that the density and total area of delineated clusters decrease with increasing contour percentile level, while the mean grain size of clusters and average size of anchor clast (i.e., the largest particle in a cluster) increase with the contour percentile level. These results support the interpretation that larger particles group as clusters and protrude higher above the bed than other smaller grains. A striking feature of the delineated clusters is that anchor clasts are invariably greater than the D90 of the grain sizes even though a threshold anchor size was not adopted herein. The average areal fractal dimensions (Hausdorff-Besicovich dimensions of the projected areas) of individual clusters, however, demonstrate that clusters delineated with different contour percentile levels exhibit similar planform morphologies. Comparisons with a

Effect of percentage of low plastic fines on the unsaturated shear strength of compacted gravel soil

Directory of Open Access Journals (Sweden)

Kamal Mohamed Hafez Ismail Ibrahim

2015-06-01

Full Text Available Low plastic fines in gravel soils affect its unsaturated shear strength due to the contribution of matric suction that arises in micro and macro pores found within and between aggregates. The shear strength of five different types of prepared gravel soils is measured and is compared with a theoretical model (Fredlund et al., 1978 to predict the unsaturated shear strength. The results are consistent to a great extent except the case of dry clayey gravel soil. It is also found that on inundation of gravel soils containing plastic fines greater than 12% a considerable reduction in both the strength and the stiffness modulus is noticed. This 12% percentage is close to the accepted 15% percentage of fines given by ASTM D4318 (American society for testing material. The angle of internal friction that arises due to matric suction decreases with the increase of degree of saturation of soil. The hysteresis of some tested gravel soils is measured and found that it increases by increasing the percentage of fines.

Development of a submerged gravel scrubber for containment venting applications: summary

International Nuclear Information System (INIS)

Hilliard, R.K.; McCormack, J.D.; Postma, A.K.

1981-01-01

Although hypothetical core disruptive accidents (HCDAs) are not design basis accidents for breeder reactor plants, extensive assessments of HCDA consequences have been made and design features for providing margins beyond the design base have been considered for future fast reactor plants. One feature proposed for increasing the safety margin is a containment vent and/or purge system which would mitigate the challenge to containment integrity resulting from excessive temperature and pressure or excessive hydrogen. A cleanup system would be required for removal of vented aerosols and condensible vapors to mitigate radiological consequences to the environment. A study is in progress at HEDL to select and develop a suitable air cleaning system for use in potential breeder reactor containment venting applications. A concept was conceived whereby the passiveness and high loading capacity of a water pool scrubber was combined with the high efficiency of a sand and gravel bed. It was termed a Submerged Gravel Scrubber (SGS). A schematic drawing of the concept is shown. The SGS consists of a bed of gravel (or other packing) submerged in a pool of water

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

Science.gov (United States)

Calle, Mikel; Alho, Petteri; Benito, Gerardo

2017-05-01

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

Response of Vegetation on Gravel Bars to Management Measures and Floods: Case Study From the Czech Republic

Directory of Open Access Journals (Sweden)

Eremiášová Renata

2014-08-01

Full Text Available This article investigates response of vegetation on gravel bars to management measures and floods. The management measures consisted of the partial removal of gravel and vegetation cover, and were applied to six gravel bars on the Ostravice River, Czech Republic. Unexpected floods occu-rred in 2010, with the amplitude of 5- to 50-year repetition. Research of vegetation on the gravel bars consisted of vegetation survey before the management works; the monitoring of vegetation development over the following year and the verification of the relationships of species diversity, successional stages and the biotope conditions with the help of multivariate analysis (detrended correspondence analysis. Vegetation on the gravel bars was at different successional stages, and had higher diversity and vegetation cover before the management measures and floods. The mul-tivariate analysis revealed a shift toward initial successional stages with high demand on moisture, temperature and light after both management measures and floods.

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

Science.gov (United States)

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

2008-03-01

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

Influence of vegetation and gravel mesh on the tertiary treatment of wastewater from a cosmetics industry.

Science.gov (United States)

Vlyssides, Apostolos G; Mai, Sofia T H; Barampouti, Elli Maria P; Loukakis, Haralampos N

2009-07-01

To estimate the influence of gravel mesh (fine and coarse) and vegetation (Phragmites and Arundo) on the efficiency of a reed bed, a pilot plant was included after the wastewater treatment plant of a cosmetic industry treatment system according to a 22 factorial experimental design. The maximum biochemical oxygen demand (BOD5), chemical oxygen demand (COD) and total phosphorous (TP) reduction was observed in the reactor, where Phragmites and fine gravel were used. In the reactor with Phragmites and coarse gravel, the maximum total Kjeldahl nitrogen (TKN) and total suspended solids (TSS) reduction was observed. The maximum total solids reduction was measured in the reed bed, which was filled with Arundo and coarse gravel. Conclusively, the treatment of a cosmetic industry's wastewater by reed beds as a tertiary treatment method is quite effective.

Stabilizing cinder gravels for heavily trafficked base course ...

African Journals Online (AJOL)

Investigation into the improvement of natural cinder gravels with the use of stabilization techniques was made using samples collected from quarry sites near Alemgena and Lake Chamo. Mechanical and cement stabilizations were investigated in two subsequent phases. In the first phase, optimum amount of fine soils that ...

Using multiple bed load measurements: Toward the identification of bed dilation and contraction in gravel-bed rivers

Science.gov (United States)

Marquis, G. A.; Roy, A. G.

2012-02-01

This study examines bed load transport processes in a small gravel-bed river (Béard Creek, Québec) using three complementary methods: bed elevation changes between successive floods, bed activity surveys using tags inserted into the bed, and bed load transport rates from bed load traps. The analysis of 20 flood events capable of mobilizing bed material led to the identification of divergent results among the methods. In particular, bed elevation changes were not consistent with the bed activity surveys. In many cases, bed elevation changes were significant (1 to 2 times the D50) even if the bed surface had not been activated during the flood, leading to the identification of processes of bed dilation and contraction that occurred over 10% to 40% of the bed surface. These dynamics of the river bed prevent accurate derivation of bed load transport rates from topographic changes, especially for low magnitude floods. This paper discusses the mechanisms that could explain the dilation and contraction of particles within the bed and their implications in fluvial dynamics. Bed contraction seems to be the result of the winnowing of the fine sediments under very low gravel transport. Bed dilation seems to occur on patches of the bed at the threshold of motion where various processes such as fine sediment infiltration lead to the maintenance of a larger sediment framework volume. Both processes are also influenced by flood history and the initial local bed state and in turn may have a significant impact on sediment transport and morphological changes in gravel-bed rivers.

Treatment of heavy metals by iron oxide coated and natural gravel media in Sustainable urban Drainage Systems.

Science.gov (United States)

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.

Environmental Assessment and Final Finding of No Significant Impact for Lantirn Village & Camera I Site Upgrades Fort Wainwright Yukon Training Area Fort Wainwright, Alaska

Science.gov (United States)

2009-08-01

overlying stratified sands, silts, and gravel. Depressions in the alluvial plains are often interbedded with thick peat layers and usually underlain...layers of peat typical of both north slopes and drainage bottoms/ depressions are underlain by permafrost, while south slopes are generally free of...aspen, and balsam poplar. Willows, alder, wild rose, blueberry, and highbush cranberry are common shrubs. o Upland Mixed Forest: Mixed forests

Final Environmental Assessment (EA) Addressing the Repair of Runway 05/23 at Fairchild Air Force Base, Washington

Science.gov (United States)

2009-11-01

farmland is defined as land that has the best combination of physical and chemical characteristics for producing food, feed, forage, fiber , and...flows. Layers of basalt could be as much as 500 feet thick with gravel, silt, or pyroclastic deposits interbedded. During the Pleistocene (from...unconformably atop the bedrock and is composed of weakly lithified sedimentary deposits from a Miocene-aged shallow lake. The Columbia River Basalts

Frost Resistance and Permeability of Cement Stabilized Gravel used as Filling Material for Pearl-Chain Bridges

DEFF Research Database (Denmark)

Lund, Mia Schou Møller; Hansen, Kurt Kielsgaard; Hertz, Kristian Dahl

2014-01-01

several requirements on its moisture properties. In this paper the frost resistance, the liquid water permeability and the water vapour permeability of cement stabilized gravel are examined for two different cement contents. It is found that a small increase in cement content from 4% to 5% increases...... the 28-days compressive strength from 6.2 MPa to 12.3 MPa. The frost resistance of cement stabilized gravel with 5% cement content is better than for cement stabilized gravel with 4% cement content. The liquid water permeability coefficient and the water vapour permeability coefficient are significantly...

Radiological characteristic of an area reclaimed by means of an ash-gravel power plant wastes

International Nuclear Information System (INIS)

Zak, A.; Biernacka, M.; Kusyk, M.; Mamont-Ciesla, K.; Florowska, K.

2002-01-01

A sand excavation after extraction of gravel and sand was filled with an ash-gravel mix. The mix was covered with shielding layers of clay and soil and grass was cultivated on it. Investigations of radiological characteristic such as: gamma radiation dose rate, radon concentration in soil air and radionuclide concentration in the ground were carried out in the both areas reclaimed one and in the vicinity of it. Radon exhalation coefficients were determined for uncovered ash-gravel mix layer, the shielding soil layer and for the ground in the vicinity. Analysis of the results revealed that the reclaimed area can be used for building development. (author)

GRAIN-SIZE MEASUREMENTS OF FLUVIAL GRAVEL BARS USING OBJECT-BASED IMAGE ANALYSIS

Directory of Open Access Journals (Sweden)

Pedro Castro

2018-01-01

Full Text Available Traditional techniques for classifying the average grain size in gravel bars require manual measurements of each grain diameter. Aiming productivity, more efficient methods have been developed by applying remote sensing techniques and digital image processing. This research proposes an Object-Based Image Analysis methodology to classify gravel bars in fluvial channels. First, the study evaluates the performance of multiresolution segmentation algorithm (available at the software eCognition Developer in performing shape recognition. The linear regression model was applied to assess the correlation between the gravels’ reference delineation and the gravels recognized by the segmentation algorithm. Furthermore, the supervised classification was validated by comparing the results with field data using the t-statistic test and the kappa index. Afterwards, the grain size distribution in gravel bars along the upper Bananeiras River, Brazil was mapped. The multiresolution segmentation results did not prove to be consistent with all the samples. Nonetheless, the P01 sample showed an R2 =0.82 for the diameter estimation and R2=0.45 the recognition of the eliptical ft. The t-statistic showed no significant difference in the efficiencies of the grain size classifications by the field survey data and the Object-based supervised classification (t = 2.133 for a significance level of 0.05. However, the kappa index was 0.54. The analysis of the both segmentation and classification results did not prove to be replicable.

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

Directory of Open Access Journals (Sweden)

Qing Zeng

Full Text Available 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.

MANUAL. Fly ash in civil engineering, Gravel roads; HANDBOK. Flygaska i mark- och vaegbyggnad, Grusvaegar

Energy Technology Data Exchange (ETDEWEB)

Munde, Hanna; Svedberg, Bo; Macsik, Josef; Maijala, Aino; Lahtinen, Pentti; Ekdahl, Peter; Neren, Jens [Vattenfall AB, Stockholm (Sweden). Vaerme Norden

2006-01-15

Fly ash based on biofuels or coal has been used as construction material for a long time in roads and other civil engineering applications. Some example, where it has been used in roadbase and subbase of gravel roads, are in the counties of Uppsala, Soedermanland, Vaestmanland and in Finland. The use of fly ash has contributed to good function for example as bearing capacity, thaw and frost capacity and good durability. This has also reduced costs for maintenance. The objective of this project was to develop a manual to provide a base for contemporary use of fly ash in road constructions. In the manual experience from studies, field tests and regulations has been compiled. The manual handles fly ash as base for products to be used in base and subbase in gravel roads. Future user of the guidelines are mainly consultant engineers and contractors. However the aim of the manual is to also support road administrators, environmental authorities and industry. The project has been carried out parallel to another ongoing national project titled 'Guidelines, Use of alternative materials in civil engineering'. The objective of that project is to establish a base for handling of alternative materials in Sweden. Fly ash in gravel roads are mainly used in two typical applications, one without any additive in a single layer and one with fly ash mixed with gravel. The use of flyash provides functional properties such as increased stiffness, stability and enhanced frost and thaw capacity for the road construction in total. Furthermore the products based on fly ash will have low permeability and good frost and thaw durability. These properties are for example related to fly ash quality, design and construction and are in general expected to be better than for traditional constructions using, for example, sand or gravel. The properties can be enhanced further by using binders such as cement and Merit. Fly ash should always be used above the ground water table with

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

Science.gov (United States)

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

1996-01-01

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

Sea Dredged Gravel versus Crushed Granite as Coarse Aggregate for Self Compacting Concrete in Aggressive Environment

DEFF Research Database (Denmark)

Sørensen, Eigil V.; Kristensen, Lasse Frølich

2007-01-01

Properties of self compacting concrete (SCC) with two types of coarse aggregate - sea dredged gravel with smooth and rounded particles and crushed granite with rough and angular particles - have been studied. Sea gravel allowed a higher aggregate proportion in the concrete leading to a higher...

Evolution of completion tools gravel pack systems for deep water

Energy Technology Data Exchange (ETDEWEB)

Pineda, Francisco [BJ Services Company, Houston, TX (United States); Vilela, Alvaro; Montanha, Roberto; Hightower, Chad; Acosta, Marco; Farias, Rodrigo [BJ Services do Brasil Ltda., Rio de Janeiro, RJ (Brazil)

2004-07-01

Conventional gravel pack or frac pack completions typically require the use of wash pipe to act as a conduit for fluid returns as well as to carry a shifting mechanism to open or close a return port. Using properly sized wash pipe can enhance the placement of the gravel across the entire annular space and the formation. It can also be used in conjunction with a shifting mechanism and a sliding sleeve to force the fluid returns to pass through the bottom of the screen. It can allow a wash-down capability while running the assembly into an open hole. In specialty systems, it can even act as a pumping conduit for post-gravel pack stimulation. However, the use of wash pipe, especially in long horizontal wells, means the loss of valuable rig time due to make up and break out of the wash pipe, or recovery if the wash pipe is stuck. Economic considerations, along with completion efficiencies, are especially important on deep water completions. Not using wash pipe reduces rig time, generating significant cost savings, and also eliminates the risk of a fishing operation. This paper reviews conventional wash pipe applications and describes new systems that accomplish the same goal with a minimum amount of wash pipe or no wash pipe at all. (author)

Soft Asphalt and Double Otta Seal—Self-Healing Sustainable Techniques for Low-Volume Gravel Road Rehabilitation

Directory of Open Access Journals (Sweden)

Audrius Vaitkus

2018-01-01

Full Text Available Increased traffic flow on low-volume gravel roads and deficiencies of national road infrastructure, are increasingly apparent in Lithuania. Gravel roads do not comply with requirements, resulting in low driving comfort, longer travelling time, faster vehicle amortization, and dustiness. The control of dustiness is one of the most important road maintenance activities on gravel roads. Another important issue is the assurance of required driving comfort and safety. Soft asphalt and Otta Seal technologies were proposed as a sustainable solution for the improvement of low-volume roads in Lithuania. Five gravel roads were constructed with soft asphalt, and 13 gravel roads were sealed with double Otta Seal, in 2012. The main aim of this research was to check soft asphalt and double Otta Seal’s ability to self-heal, on the basis of the results of the qualitative visual assessment of pavement defects and distress. The qualitative visual assessment was carried out twice a year following the opening of the rehabilitated road sections. The results confirmed soft asphalt and double Otta Seal’s ability to self-heal. The healing effect was more than 13% and 19% on roads with soft asphalt and double Otta Seal, respectively. In addition, on some roads, all cracks observed in spring self-healed during summer.

Fly-ash and Green liquor as binder in gravel road stabilization. Pilot study at Iggesund; Flygaska-Groenlutslamstabiliserad skogsbilvaeg. Fallstudie Iggesund

Energy Technology Data Exchange (ETDEWEB)

Macsik, Josef; Erlandsson, Aasa; Wexell, Bengt-Arne

2009-03-15

The quality of gravel roads is of importance for public and the forestry industry. Frost damages lead to the closure of roads due to reduced bearing capacity, settlements and tracks made by wheel. Lately these frost damages have worsened due to milder winter temperatures. The need to improve the quality of these roads and to minimize the periods when the roads are closed is ever increasing. Several Swedish and Finnish projects have shown that rest materials from the paper industry can improve bearing capacity of roads. Both green liquor and fly ash was used successfully in an earlier project as pelletized mineral nutrient in forest soil. In this project fly ash and green liquor from Iggesund Paperboard was used as a binder during stabilization of a gravel road. The aim was to improve bearing capacity of a gravel road, mainly during the thawing period. The target group of the project was local road associations, forestry industry, which have a need to improve road quality, the paper industry which produce suitable rest materials and local environmental agencies. During an initial laboratory investigation proper binder recipe, based on fly ash, green liquor and cement was chosen. The laboratory investigation and earlier studies indicate in order to increase resistance to frost damage cement should be included in the binder. The aim was to stabilize ballast and improve the stabilized road materials shear strength, frost susceptibility. Total elemental content and Leachability was also investigated. Based on the results the local environmental agency was notified. During spring of 2008 two road sections, about 2 km was stabilized. The stabilized road was investigated during autumn 2008 regarding bearing capacity and environmental impact. The stabilization of the road section was estimated to cause minor impact on the recipient. The local environmental agency approved the stabilization of the road section, however increased the follow up effort with more analyses

stabilization of cinder gravel with cment for base course

African Journals Online (AJOL)

Girma Berhanu

techniques was made using samples collected from quarry sites near ... design standards for heavily trafficked base course without adding ... Cinder gravel, Mechanized stabilization, Optimum cement content ... respectively. In the presentation through out the .... here to indicate the general response of cement stabilization in ...

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

Energy Technology Data Exchange (ETDEWEB)

Waugh, W.J.; Link, S.O. (Pacific Northwest Lab., Richland, WA (USA))

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.

Large landslides, composed of megabreccia, interbedded in Miocene basin deposits, southeastern Arizona

Science.gov (United States)

Krieger, Medora Louise Hooper

1977-01-01

The landslides in the Kearny and El Capitan Mountain quadrangles, Pinal and Gila Counties, Ariz., are tabular or lens like masses of megabreccia enclosed in Miocene basin deposits. The megabreccias within individual slide blocks are composed of pervasively brecciated Precambrian and younger formations that remain in normal stratigraphic sequence, indicating that each landslide moved as a fairly coherent mass. The megabreccias consist of fresh, mostly angular rock fragments in a comminuted matrix of the same composition as the fragments. The matrix ranges in amount from sparse to abundant. Where the matrix is sparse, the fragments fit tightly with little or no rotation. Locally fragments are rotated but not moved far; most units within a slide block are lithologically homogeneous. The Kearny landslides are conformably interbedded in steeply east-dipping playa and alluvial deposits. They form map units from a few tens of meters to nearly 4 km long and from less than 1 to 270 m wide. Narrow ridges expose sections through the landslides at about right angles to the direction of movement. The upper (proximal) ends have been eroded; the lower (distal) ends are buried. The El Capitan landslide dips very gently southward. Although partly dissected during erosion of the enclosing alluvial and lakebed deposits, its approximate original outline is still preserved. It forms a thin sheet, 5-15 m thick and at least 3.8 km long; the maximum outcrop width, near its distal end, is about 1.5 km. The Kearny landslides show little evidence of having exerted differential pressure on the underlying soft playa and alluvial deposits, and the contacts with the underlying sediments have little relief. The distal end of the El Capitan landslide, on the other hand, has considerable relief. As the landslide came to an abrupt stop, the end plowed into the underlying sediments, compressing them into fol9.s and forming sandstone dikes. The source of the El Capitan landslide is a well

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

Science.gov (United States)

2010-07-01

... § 644.551 Equal opportunity—sales of timber, embedded sand, gravel, stone, and surplus structures... 32 National Defense 4 2010-07-01 2010-07-01 true Equal opportunity-sales of timber, embedded sand, gravel, stone, and surplus structures. 644.551 Section 644.551 National Defense Department of Defense...

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

Science.gov (United States)

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

Sedimentary fabrics of the macrotidal, mud-dominated, inner estuary to fluvio-tidal transition zone, Petitcodiac River estuary, New Brunswick, Canada

Science.gov (United States)

Shchepetkina, Alina; Gingras, Murray K.; Zonneveld, John-Paul; Pemberton, S. George

2016-03-01

The study provides a detailed description of mud-dominated sedimentary fabrics and their application for the rock record within the inner estuary to the fluvial zone of the Petitcodiac River estuary, New Brunswick, Canada. Sedimentological characteristics and facies distributions of the clay- and silt-rich deposits are reported. The inner estuary is characterized by thick accumulations of interbedded silt and silty clay on intertidal banks that flank the tidally influenced channel. The most common sedimentary structures observed are parallel and wavy lamination, small-scale soft-sediment deformation with microfaults, and clay and silt current ripples. The tidal channel contains sandy silt and clayey silt with planar lamination, massive and convolute bedding. The fluvio-tidal transition zone is represented by interbedded trough cross-stratified sand and gravel beds with planar laminated to massive silty mud. The riverine, non-tidal reach of the estuary is characterized by massive, planar tabular and trough cross-stratified gravel-bed deposits. The absence of bioturbation within the inner estuary to the fluvio-tidal transition zone can be explained by the following factors: low water salinities (0-5 ppt), amplified tide and current speeds, and high concentrations of flocculated material in the water body. Notably, downstream in the middle and outer estuary, bioturbation is seasonally pervasive: in those locales the sedimentary conditions are similar, but salinity is higher. In this study, the sedimentological (i.e., grain size, bedding characters, sedimentary structures) differences between the tidal estuary and the fluvial setting are substantial, and those changes occur over only a few hundred meters. This suggests that the widely used concept of an extensive fluvio-tidal transition zone and its depositional character may not be a geographically significant component of fluvial or estuary deposits, which can go unnoticed in the study of the ancient rocks.

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

International Nuclear Information System (INIS)

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

Seasonal movement change of sediments using RFID tracer monitoring in composite gravel beach, west coast of Korea

Science.gov (United States)

Han, M.; Yu, J.; Yang, D. Y.; Kim, J. W.

2017-12-01

The purpose of this study is to investigate seasonal movement patterns of gravel movements on the west coast of Korean peninsula. This study aims improve understanding of the process of coastal sediments movement and contribute to coastal erosion management. The study site is Taean Bangpo Beach, which is characterized by its macro tide and composite gravel beach (CGB). In this study, we carried out a radio frequency identifier (RFID) tracer movement monitoring experiment. Four hundred tracers, similar in size and shape to beach sediment, were inserted into the beach in February and December 2015. From the results, it was confirmed that generally, gravel moved southward in the winter and northward in the summer. It was also confirmed that the gravel moved long distances in the summer and winter, but much shorter distances in the spring. At the end of the results, it is confirmed that the tracer recovery rate in summer is lower than in winter. Bangpo Beach was influenced by strong wind and wave energy driven by the East Asian winter monsoon, and by normal tidal energy during the other seasons. It means that seasonal variation of gravel movement in the beach is attributed to the difference of seasonal energy conditions. In addition, it is interpreted that the sand at the intertidal zone cannot be removed in the summer when the wave energy is weak, causing the tracer to be buried. This study is expected to contribute to the study of composite gravel beach and coastal coarse sediment movement which have been lacking in research.

Labour-based bitumen roads as cost-effective alternatives to conventional gravel wearing courses

CSIR Research Space (South Africa)

Paige-Green, P

2004-09-01

Full Text Available and streets. The potential for large-scale application of labour-based road works is therefore enormous. Delivery of a quality product is seen as key to the acceptance of labour-based road works. In Gundo Lashu it was realised early on that finding good... quality wearing course gravel in itself constituted a major problem in many areas of the province, thus bringing the costs for a fully rehabilitated and gravelled 5.5m wide road to about R230 000 in some instances. Aside from depleting an increasingly...

Horizontal single-trip gravel pack and selective simulation system for deep water extended reach wells

Energy Technology Data Exchange (ETDEWEB)

Pineda, Francisco [BJ Services Company, Houston, TX (United States); Vilela, Alvaro; Montanha, Roberto; Acosta, Marco; Farias, Rodrigo [BJ Services do Brasil Ltda., Rio de Janeiro, RJ (Brazil)

2004-07-01

Most of the reservoirs located in the deep water and ultra-deep water offshore South America are described as unconsolidated sandstone that require sand control on both producers and water injection wells. Horizontal Open Hole Gravel Pack completions are the preferred method of development. If completing heavy oil reservoirs, there is a necessity of longer horizontal open hole sections. Low fracture gradients may limit the length of gravel pack in the open hole section because of the pressure increase during the Beta wave proppant deposition phase. This system allows the gravel pack assembly to be installed and the gravel pack to be pumped during the alpha and beta wave deposition phases without the limitation of high pressures that could fracture the well. The benefits of the Horizontal Single-Trip Gravel Pack and Selective Stimulation System (HSTSSS) using the differential valve include the ability to complete longer horizontal intervals, valuable rig-time savings and, efficient mechanical diversion of the stimulation fluid. This paper outlines the application of the HSTSSS system using a differential valve to complete a horizontal well in offshore deep waters. The need for a differential valve is primarily in horizontal gravel packing operations when normal circulating rates and pressures around the open hole would exceed formation break down pressure. The valve is intended to be easily spaced out and run in the wash pipe. At a predetermined differential pressure the valve opens and the return flow path distance around the bottom of the tailpipe is shortened, thus reducing back pressure preventing filter cake damage without slowing the pump rate. In addition the said valve has to close to allow the selective stimulation to take place. Economic considerations along with completion efficiencies are especially important on deep water, subsea completions. The utilization of differential valves allows completion of extended-reach open hole wells and/or low fracture

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

Science.gov (United States)

Stewart, Robert L.; Fox, James F.

2017-06-01

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

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

Science.gov (United States)

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

Particulate removal processes and hydraulics of porous gravel media filters

Science.gov (United States)

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

Isotope Investigations of Groundwater Movement in a Coarse Gravel Unsaturated Zone

Energy Technology Data Exchange (ETDEWEB)

Mali, N. [Geological Survey of Slovenia, Department of Hydrogeology, Ljubljana (Slovenia); Kozar-Logar, J. [Jozef Stefan Institute, Ljubljana (Slovenia); Leis, A. [Institute of Water Resources Management, Hydrogeology and Geophysics, Joanneum Research Forschungsgesellschaft mbH, Graz (Austria)

2013-07-15

The unsaturated zone above an aquifer serves as a water reservoir which discharges water and possible pollution to the saturated zone. This paper presents the application of oxygen-18 and tritium isotope methods in the study of groundwater transport processes in the unsaturated zone of Selniska Dobrava coarse gravel aquifer. The Selniska Dobrava gravel aquifer is an important water resource for Maribor and its surroundings, therefore the determination of transport processes in the unsaturated zone is important regarding its protection. Groundwater flow characteristics were estimated using isotopes and based on experimental work in a lysimeter. Tritium investigation results were compared with the results of long term oxygen-18 isotope investigation. In this paper the analytical approach, results and interpretation of {delta}{sup 18}O and tritium measurements in the unsaturated zone are presented. (author)

A laboratory experiment on the evolution of a sand gravel reach under a lack of sediment supply

NARCIS (Netherlands)

Orru, C.; Chavarrias Borras, V.; Ferrara, V.; Stecca, G.; Blom, A.

2015-01-01

A flume experiment was conducted to examine the evolution of a sand-gravel reach under a lack of sediment supply. A bed composed of a bimodal sediment mixture was installed with a uniform slope and an gradual fining pattern. At the upstream end of the flume the initial bed consisted of 100% gravel,

Removal of Zn(II) from electroplating effluent using yeast biofilm formed on gravels: batch and column studies

Science.gov (United States)

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

Thermoluminescence dating of Rio Claro and Piracununga formations

International Nuclear Information System (INIS)

Ferreira, Sandra Regina; Chang, Maria Rita Caetano

2008-01-01

The Rio Claro and Piracununga formations cover extensive areas of the Paulista Peripheral Depression, dominantly in the region of Rio Claro and Piracununga cities. These units lie over the Corumbatai and Piramboia formations, exhibiting discordant contacts. The Rio Claro and Piracununga formations are composed of fine to medium sand facies, showing local cross-stratifications and parallel beddings with thin interbeddings of mud and gravel. These sands were dated by the Thermoluminescence Method, which indicated they were from the Pleistocene age. The oldest age (745,000 years BP) was found in deposits of the Rio Claro Formation; the other ages varied from 400,000 years BP to 145,000 years BP, for both formations. The youngest age (15,000 years BP - close to Pleistocene/ Holocene limit) was found in colluvial deposits, which rest on the Piracununga Formation. (author)

Spatial patterns in gravel habitats and communities in the central and eastern English Channel

Science.gov (United States)

Coggan, Roger; Barrio Froján, Christopher R. S.; Diesing, Markus; Aldridge, John

2012-10-01

The distribution of sediment type and benthic communities in the central and eastern English Channel is shown to be polarised around a distinctive local hydrodynamic feature. The seabed in the region includes an extensive area of gravel substrate which is both an important habitat for benthic marine fauna and a valuable source of material for the marine aggregate industry. Effective management of the area is predicated on an understanding of whether it represents a single homogeneous unit, or several different units that may need to be managed in different ways. The aim of this study was to provide information that would inform such management decisions. Spatial patterns in gravel habitats and communities were studied by investigating the physical environment through modelled and empirical data, and the distribution of infauna and epifauna along an east-west trending transect. A common spatial pattern was observed in both physical and biological parameters, but rather than indicating a simple longitudinal gradient, there was a distinct polarisation around a central feature, a bedload parting (BLP) zone situated between the Isle of Wight and Cotentin peninsula. Sediments and communities at the eastern and western ends of the transect were more similar to each other than to those in the middle. The strong hydrodynamic regime in the BLP area controls sediment distribution, transporting finer material, mainly sand, away from the mid transect area. The pattern in sand content of the substrate mirrors the magnitude of the potential bedload transport, which is complex in this region due to the interplay between the M2 and M4 tidal constituents and produced a series of erosional and depositional zones. The structure of benthic communities reflected the local substrate and hydrodynamic conditions, with sponges observed among the stable substrates and stronger currents that characterised the mid transect area, while infauna became more diverse towards the ends of the

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

Science.gov (United States)

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.

Morphological evolution of the Maipo River in central Chile: Influence of instream gravel mining

Science.gov (United States)

Arróspide, Felipe; Mao, Luca; Escauriaza, Cristián

2018-04-01

Instream gravel mining is one of the most important causes of channel degradation in South America, specifically in rivers located near large metropolitan areas with rapidly growing cities, where no river management strategies exist. In the western region of the continent, many of these rivers belong to Andean systems, in which significant parts of the watersheds are located in mountain areas at high altitude, with considerable seasonal rainfall variability and steep channel slopes. In these rivers, gravel mining has produced significant incision of the channels with serious physical and ecological consequences, affecting habitats, modifying the supply and transport of sediments, and amplifying the risk to infrastructure in and around the channel during floods. In spite of the degraded conditions of many channels, no quantitative studies of the geomorphic impacts of gravel mining have been carried out in the region, mostly because of the insufficient and sparse data available. In this investigation we perform an analysis of the morphodynamic evolution in a section of the Maipo River in the metropolitan region of Santiago, Chile. This river is economically the most important in the country, as it provides drinking and irrigation water to urban and rural areas, is utilized by the energy generation industry, and runs along and below critical infrastructure. We have collected and analyzed data from 1954 to 2015, during which the city population increased by more than 5 million inhabitants whose presence accelerated land use changes. The analysis shows a rapid morphological evolution of the channel where in 31 years effects such as: river sections showing incision of up to 20 m, an increase of the area affected by gravel mining from 86.62 to 368.13 ha, and a net erosion volume of 39.4 million m3 can be observed. This work yields quantitative information on the consequences of gravel mining in the Maipo River, providing the necessary data to develop an integrated

Synthesis of AL-MCM-41 using gravel drilling the source of silica from wells drilling

International Nuclear Information System (INIS)

Fontes, M.S.B.; Costa, C.C.; Melo, D.M.A.; Viana, L.M.; Viana, S.O.; Santos, L.M.

2016-01-01

The aim of this study was to synthesize Al-MCM-41 using gravel drilling as alternative source of silica, aiming at sustainable production and low cost. For hydrothermal synthesis of Al-MCM-41 was used gravel and sodium silicate as source of silica and sodium, respectively. The structural driver used was cetyltrimethylammonium bromide (CTMABr) and solvent distilled water. The hydrothermal synthesis was conducted at 100 ° C in a Teflon autoclave 45 ml jacketed stainless steel for a period of 120 hours with daily correcting pH (range 9-10) using 30% acetic acid. The material obtained was filtered, washed, dried at 100 ° C for 3 hours and then calcined at 550 ° C for 2 hours. Then it was characterized by XRD, FTIR and TG. For the results of characterization has been observed that the use of the gravel drilling as a source of silica was promising alternative for producing a mesoporous material with a high degree of hexagonal ordering. (author)

Physical Characteristics of Laboratory Tested Concrete as a Substituion of Gravel on Normal Concrete

Science.gov (United States)

Butar-butar, Ronald; Suhairiani; Wijaya, Kinanti; Sebayang, Nono

2018-03-01

Concrete technology is highly potential in the field of construction for structural and non-structural construction. The amount uses of this concrete material raise the problem of solid waste in the form of concrete remaining test results in the laboratory. This waste is usually just discarded and not economically valuable. In solving the problem, this experiment was made new materials by using recycle material in the form of recycled aggregate which aims to find out the strength characteristics of the used concrete as a gravel substitution material on the normal concrete and obtain the value of the substitution composition of gravel and used concrete that can achieve the strength of concrete according to the standard. Testing of concrete characteristic is one of the requirements before starting the concrete mixture. This test using SNI method (Indonesian National Standard) with variation of comparison (used concrete : gravel) were 15: 85%, 25: 75%, 35:65%, 50:50 %, 75: 25%. The results of physical tests obtained the mud content value of the mixture gravel and used concrete is 0.03 larger than the standard of SNI 03-4142-1996 that is equal to 1.03%. so the need watering or soaking before use. The water content test results show an increase in the water content value if the composition of the used concrete increases. While the specific gravity value for variation 15: 85% until 35: 65% fulfilled the requirements of SNI 03-1969-1990. the other variasion show the specifics gravity value included on the type of light materials.

Water quality in gravel pits in the Bratislava area

International Nuclear Information System (INIS)

Flakova, R.; Rohacikova, A.; Zenisova, Z.

1999-01-01

The gravel pits around Bratislava have an esthetic, urban and recreational function. Open water table areas are in a direct contact with the air and acquire some characteristics of the surface water. The quality of open water table is much more susceptible to pollution than that of groundwater. Wet and dry deposition, water inflow from the surrounding surface, unmanageable sewerage effluents, solid and liquid wastes, but also the water birds contribute to the pollution. The Department of Hydrogeology has monitored the water quality in six gravel pits (Cunovo, Drazdiak, Strkovec, Pasienky, Zlate Piesky, Vajnory) since 1976 with an an interruption between 1988 - 1993. Two sampling per year have been made since 1994 and after 1998 the analyses have been supplemented by Na, K, Fe, Mn, by oxygen regime parameters, by trace elements (As, Ag, Cd, Co, Cu, Cr, Hg, Ni, Pb, V, Zn) and by organic pollutants. As regards the oxygen regime, the water quality pits is very good. The anthropogenic influence is expressed mainly by the increased contents of sulfates and chlorides. Most problematic trace elements are the mercury and vanadium (Drazdiak, Zlate Piesky and Vajnory). (authors)

Sorption of activation products on London clay and Dungeness aquifer gravel

International Nuclear Information System (INIS)

Baston, G.M.N.; Berry, J.A.; Littleboy, A.K.; Pilkington, N.J.

1992-01-01

The sortpion of a series of activation-product radionuclides onto London clay and Dungeness aquifer gravel from the nuclear reactor sites at Bradwell and Dungeness, has been examined. Batch sorption and through-diffusion experiments with clay determined chlorine as the chloride ion to be effectively non-sorbing; calcium to be weakly sorbing, whereas cobalt, nickel, niobium and samarium were moderately to strongly sorbing and silver was strongly sorbing. Distribution ratios (R D values) for Nb, Sm and Ag were found to have a strong dependence on the liquid-solid separation technique employed. The presence of high concentrations of calcium hydroxide led to lower values of R D for radioactive Ca but higher R D values for Sm and Ag. The sorption of Ni showed no apparent dependence on groundwater composition at low levels of dissolved organic carbon (DOC). The values of R D for Co decreased as the DOC content was increased by addition of humic materials. Batch sorption studies with aquifer gravel demonstrated that Ca is weakly sorbing whereas Nb, Ag and Eu are moderately to strongly sorbing. R D values for Ca and for Ag under neutral pH conditions show little sensitivity to the liquid/solid separation technique used. However, R D values for Nb and Eu under neutral pH conditions and for Ag in alkaline solution (pH = 11 - 12) show a marked effect. The aquifer gravel was found to be highly inhomogeneous unlike the clay and sorption was greatest on samples with a high proportion of sand, reflecting the clay mineral content. (orig.)

Geomorphic Effects of Gravel Augmentation and Bank Re-erosion on the Old Rhine River Downstream From The Kembs Dam (France, Germany)

Science.gov (United States)

Chardon, V.; Laurent, S.; Piegay, H.; Arnaud, F.; Houssier, J.; Serouilou, J.; Clutier, A.

2017-12-01

The Old Rhine is a 50 km by-passed reach downstream from the Kembs diversion dam in the Alsacian plain (France/Germany). It has been impacted by engineering works since the 19th century. This reach exhibits poor ecological functionalities due to severe geomorphological alterations (e.g., channel bed stabilization, narrowing, degradation and armoring, sediment deficit). In the frame of the Kembs power plant relicensing (2010), Électricité de France has undertaken two gravel augmentations (18 000 and 30 000 m3) and three controlled bank erosions following riprap protection removal over 300 m bank length to enhance bedload transport and habitat diversification. A first pilot gravel augmentation was also implemented in 2010 (23 000 m3). A geomorphological monitoring based on bedload tracking, grain size analyses and topo-bathymetric surveys has been performed on the three gravel augmentation reaches and one of the controlled bank erosion sites to assess the efficiency and sustainability of these actions (2010-2017). Results show that augmented gravels are entrained for a Q2 flood. Gravels moved several hundred meters for moderate floods and up to one kilometer for more intense floods (Q15), while sediment deposition mainly diffused within the channel. Morphological and grain size diversification, including sediment refinement, are still relatively limited following gravel augmentation. Furthermore, sediment armoring reestablished once the sediment wave moved more downstream, after only four to six years, due to the stability and the narrowness of the channel but also by the absence of upstream bedload supply. Habitat diversification was higher on the controlled bank erosion site thanks to the presence of two artificial groynes, even though eroded sediment volumes were lower than expected (less than 1500m3 for a Q15 flood). This monitoring demonstrates gravel augmentations are not sufficient to really diversify geomorphological conditions of the Old Rhine. Channel

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

Science.gov (United States)

Konishi, C.

2014-12-01

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

Unintended consequences of restoration: loss of riffles and gravel substrates following weir installation.

Science.gov (United States)

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. Copyright © 2012 Elsevier Ltd. All rights

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

International Nuclear Information System (INIS)

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

1995-01-01

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

Sorption of activation products on London clay and Dungeness aquifer gravel

Energy Technology Data Exchange (ETDEWEB)

Baston, G.M.N.; Berry, J.A.; Littleboy, A.K.; Pilkington, N.J. (AEA Decommissioning and Radwaste, Harwell Lab. (United Kingdom))

1992-01-01

The sortpion of a series of activation-product radionuclides onto London clay and Dungeness aquifer gravel from the nuclear reactor sites at Bradwell and Dungeness, has been examined. Batch sorption and through-diffusion experiments with clay determined chlorine as the chloride ion to be effectively non-sorbing; calcium to be weakly sorbing, whereas cobalt, nickel, niobium and samarium were moderately to strongly sorbing and silver was strongly sorbing. Distribution ratios (R[sub D] values) for Nb, Sm and Ag were found to have a strong dependence on the liquid-solid separation technique employed. The presence of high concentrations of calcium hydroxide led to lower values of R[sub D] for radioactive Ca but higher R[sub D] values for Sm and Ag. The sorption of Ni showed no apparent dependence on groundwater composition at low levels of dissolved organic carbon (DOC). The values of R[sub D] for Co decreased as the DOC content was increased by addition of humic materials. Batch sorption studies with aquifer gravel demonstrated that Ca is weakly sorbing whereas Nb, Ag and Eu are moderately to strongly sorbing. R[sub D] values for Ca and for Ag under neutral pH conditions show little sensitivity to the liquid/solid separation technique used. However, R[sub D] values for Nb and Eu under neutral pH conditions and for Ag in alkaline solution (pH = 11 - 12) show a marked effect. The aquifer gravel was found to be highly inhomogeneous unlike the clay and sorption was greatest on samples with a high proportion of sand, reflecting the clay mineral content. (orig.).

Radon diffusion studies in air, gravel, sand, soil and water

International Nuclear Information System (INIS)

Singh, B.; Singh, S.; Virk, H.S.

1993-01-01

Radon isotopes are practically inert and have properties of gases under conditions of geological interest. During their brief lives their atoms are capable of moving from sites of their generation. Radon diffusion studies were carried out in air, gravel, sand, soil and water using silicon diffused junction electronic detector, Alphameter-400. Diffusion constant and diffusion length is calculated for all these materials. (author)

Evaluation of Hydraulic Parameters Obtained by Different Measurement Methods for Heterogeneous Gravel Soil

Directory of Open Access Journals (Sweden)

Chen Zeng

2012-01-01

Full Text Available Knowledge of soil hydraulic parameters for the van Genuchten function is important to characterize soil water movement for watershed management. Accurate and rapid prediction of soil water flow in heterogeneous gravel soil has become a hot topic in recent years. However, it is difficult to precisely estimate hydraulic parameters in a heterogeneous soil with rock fragments. In this study, the HYDRUS-2D numerical model was used to evaluate hydraulic parameters for heterogeneous gravel soil that was irregularly embedded with rock fragments in a grape production base. The centrifugal method (CM, tensiometer method (TM and inverse solution method (ISM were compared for various parameters in the van Genuchten function. The soil core method (SCM, disc infiltration method (DIM and inverse solution method (ISM were also investigated for measuring saturated hydraulic conductivity. Simulation with the DIM approach revealed a problem of overestimating soil water infiltration whereas simulation with the SCM approach revealed a problem of underestimating water movement as compared to actual field observation. The ISM approach produced the best simulation result even though this approach slightly overestimated soil moisture by ignoring the impact of rock fragments. This study provides useful information on the overall evaluation of soil hydraulic parameters attained with different measurement methods for simulating soil water movement and distribution in heterogeneous gravel soil.

Indoor radon in houses built on gravel and sand deposits in southern Finland

Directory of Open Access Journals (Sweden)

Hutri, K.-L.

1993-06-01

Full Text Available Studies by the Finnish Centre for Radiation and Nuclear Safety (STUK have shown that, in Finland, indoor radon concentrations are almost twice as high in houses built on sand or gravel as in houses built on other soil types. The aim of this study was to assess the radon risk on eskers, ice-marginal formations, and other gravel and sand deposits on the basis of factors that can be determined from geological maps. Altogether, 514 houses built on gravel and sand deposits were selected for the study from the indoor radon database of STUK. Several geological parameters were determined. Empirical statistical models were used to assess the significance of factors affecting indoor radon in glaciofluvial deposits and the sand-dominant littoral deposits occurring in association with them. A relationship was found between increased indoor radon concentrations and the location of a house on a steep-sided esker, in the southeastern rapakivi granite area and on the upper slope or top of an esker. The steepness of the slope also increased the radon concentration in houses on steep-sided eskers. The effect of the topographic features is due to subterranean air-flows. As estimated from the very sparse till sampling, the elevated uranium concentration increased the indoor radon concentration only in houses built on littoral deposits around eskers and ice-marginal formations.

Computational fluid dynamics and experimental tests helping to understand the gravel pack displacement in petroleum wells; Fluidodinamica computacional (CFD) e testes experimentais ajudam a compreender o fenomeno do deslocamento do gravel pack em pocos de petroleo

Energy Technology Data Exchange (ETDEWEB)

Magalhaes, Joao Vicente Martins de; Leal, Rafael Amorim Ferreira; Martins, Andre Leibsohn; Calderon, Agostinho; Ferreira, Marcus Vinicius Duarte [Petrobras S.A., Rio de Janeiro, RJ (Brazil)], E-mails: ivmm@petrobras.com.br, rafaelleal@petrobras.com.br, aleibsohn@petrobras.com.br, agoscal@petrobras.com.br, mvdferreira@petrobras.com.br; Simoes, Bruno; Barbosa, Diego [Halliburton, Novo Cavaleiros, Macae, RJ (Brazil)], E-mails: bruno.simoes@halliburton.com.br, diego.barbosa@halliburton.com.br

2010-07-01

In the petroleum exploitation and production in deep water, at the fields operated by PETROBRAS, Brazil, one of the problems frequently found is the need of elimination of sand production, having in mind that the most of those fields produce from the non consolidated sandstones. The opened well Gravel Packing is the technique most used for that task. Due to the fact of Gravel Packing operations occurs at thousand of meters below the surface, it is necessary the computational simulation for forecasting how particle deposition (Gravel) in the well occurs. So, it was used the commercial pack of fluid dynamics FLUENT 12, which calculates the fluid velocity field, coupled to another commercial pack, the EDEM, based on discrete elements that treat of particle mechanics. The coupling of the two software has shown adequate the comparison of the computational results with the experimental data shows a good adjustment. Besides, it was possible to simulate problems of well early clogging, showing that the computational simulation is strong and capable of captivating such a phenomena.

Image analysis to measure sorting and stratification applied to sand-gravel experiments

NARCIS (Netherlands)

Orrú, C.

2016-01-01

The main objective of this project is to develop new measuring techniques for providing detailed data on sediment sorting suitable for sand-gravel laboratory experiments. Such data will be of aid in obtaining new insights on sorting mechanisms and improving prediction capabilities of morphodynamic

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

Science.gov (United States)

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

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

Science.gov (United States)

Peter Wilcock; John Pitlick; Yantao Cui

2009-01-01

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

Environmental laws for mining activities in Provincia de San Juan (Argentina), gravel mines exploitation

International Nuclear Information System (INIS)

Ramirez, M.; Carrascosa, H.

2007-01-01

This paper analyses San Juan Province - Argentina prevailing environmental legislation for mining activity and gravel mines. The study focuses the subject from a mining engineering point of view. (author)

Cement Type Influence on Alkali-Silica Reaction in Concrete with Crushed Gravel Aggregate

Science.gov (United States)

Rutkauskas, A.; Nagrockienė, D.; Skripkiūnas, G.

2017-10-01

Alkali-silica reaction is one of the chemical reactions which have a significant influence for durability of concrete. During alkali and silica reaction, silicon located in aggregates of the concrete, reacts with high alkali content. This way in the micropores of concrete is forming hygroscopic gel, which at wet environment, expanding and slowly but strongly destroying concrete structures. The goal of this paper- to determine the influence of cement type on alkali-silica reaction of mortars with crushed gravel. In the study crushed gravel with fraction 4/16 mm was used and four types of cements tested: CEM I 42.5 R; CEM I 42.5 SR; CEM II/A-S 42.5; CEM II/A-V 52.5. This study showed that crushed gravel is low contaminated on reactive particles containing of amorphous silica dioxide. The expansion after 14 days exceed 0.054 %, by RILEM AAR-2 research methodology (testing specimen dimension 40×40×160 mm). Continuing the investigation to 56 days for all specimens occurred alkaline corrosion features: microcracking and the surface plaque of gel. The results showed that the best resistance to alkaline corrosion after 14 days was obtained with cement CEM I 42.5 SR containing ash additive, and after 56 days with cement CEM II/A-V 52.5 containing low alkali content. The highest expansion after 14 and 56 days was obtained with cement CEM I 42.5 R without active mineral additives.

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

Science.gov (United States)

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

1998-01-01

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

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

Directory of Open Access Journals (Sweden)

K. Glasbergen

2015-03-01

Full Text Available While cohesive sediment generally represents a small fraction (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.

Water and soil loss from landslide deposits as a function of gravel content in the Wenchuan earthquake area, China, revealed by artificial rainfall simulations.

Science.gov (United States)

Gan, Fengling; He, Binghui; Wang, Tao

2018-01-01

A large number of landslides were triggered by the Mw7.9 Wenchuan earthquake which occurred on 12th May 2008. Landslides impacted extensive areas along the Mingjiang River and its tributaries. In the landslide deposits, soil and gravel fragments generally co-exist and their proportions may influence the hydrological and erosion processes on the steep slopes of the deposit surface. Understanding the effects of the mixtures of soil and gravels in landslide deposits on erosion processes is relevant for ecological reconstruction and water and soil conservation in Wenchuan earthquake area. Based on field surveys, indoor artificial rainfall simulation experiments with three rainfall intensities (1.0, 1.5 and 2.0 mm·min-1) and three proportions of gravel (50%, 66.7% and 80%) were conducted to measure how the proportion of gravel affected soil erosion and sediment yield in landslide sediments and deposits. Where the proportion of gravel was 80%, no surface runoff was produced during the 90 minute experiment under all rainfall intensities. For the 66.7% proportion, no runoff was generated at the lowest rainfall intensity (1.0 mm·min-1). As a result of these interactions, the average sediment yield ranked as 50> 66.6> 80% with different proportions of gravel. In addition, there was a positive correlation between runoff generation and sediment yield, and the sediment yield lagging the runoff generation. Together, the results demonstrate an important role of gravel in moderating the mobilization of landslide sediment produced by large earthquakes, and could lay the foundation for erosion models which provide scientific guidance for the control of landslide sediment in the Wenchuan earthquake zone, China.

A New Method for Tracking Individual Particles During Bed Load Transport in a Gravel-Bed River

Science.gov (United States)

Tremblay, M.; Marquis, G. A.; Roy, A. G.; Chaire de Recherche Du Canada En Dynamique Fluviale

2010-12-01

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 deposition site to another. Our new tracking method uses 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 temporal frequency. The Hobo was inserted into 11 artificial rocks. The rocks were seeded in Ruisseau Béard, a small gravel-bed river in the Yamaska drainage basin (Québec) where the hydraulics, particle sizes and bed characteristics are well known. The signals recorded during eight floods (Summer and Fall 2008-2009) allowed us to develop an algorithm which classifies the periods of rest and motion. We can differentiate two types of motion: sliding and rolling. The particles can also vibrate while remaining in the same position. The examination of the movement and vibration periods with respect to the hydraulic conditions (discharge, shear stress, stream power) showed that vibration occurred mostly before the rise of hydrograph and allowed us to establish movement threshold and response times. In all cases, particle movements occurred during floods but not always in direct response to increased bed shear stress and stream power. This method offers great potential to track individual particles and to establish a spatiotemporal sequence of the intermittent transport of the particle during a flood and to test theories concerning the resting periods of particles on a gravel bed.

Optimizing the use of natural gravel Brantas river as normal concrete mixed with quality fc = 19.3 Mpa

Science.gov (United States)

Limantara, A. D.; Widodo, A.; Winarto, S.; Krisnawati, L. D.; Mudjanarko, S. W.

2018-04-01

The use of natural gravel (rivers) as concrete mixtures is rarely encountered after days of demands for a higher strength of concrete. Moreover, today people have found High-Performance Concrete which, when viewed from the rough aggregate consisted mostly of broken stone, although the fine grain material still used natural sand. Is it possible that a mixture of concrete using natural gravel as a coarse aggregate is capable of producing concrete with compressive strength equivalent to a concrete mixture using crushed stone? To obtain information on this, a series of tests on concrete mixes with crude aggregates of Kalitelu Crusher, Gondang, Tulungagung and natural stone (river gravel) from the Brantas River, Ngujang, Tulungagung in the Materials Testing Laboratory Tugu Dam Construction Project, Kab. Trenggalek. From concrete strength test results using coarse material obtained value 19.47 Mpa, while the compressive strength of concrete with a mixture of crushed stone obtained the value of 21.12 Mpa.

Gravel bar thermal variability and its potential consequences for CO2 evasion from Alpine coldwater streams

Science.gov (United States)

Boodoo, Kyle; Battin, Tom; Schelker, Jakob

2017-04-01

Gravel bars (GB) are ubiquitous in-stream structures with relatively large exposed surfaces, capable of absorbing heat and possibly acting as a heat source to the underlying hyporheic zone (HZ). The distinctive mixing of groundwater and surface water within their HZ largely determines its characteristic physical and biogeochemical properties, including temperature distribution. To study thermal variability within GBs and its possible consequences for CO2 evasion fluxes we analysed high frequency spatio-temporal data for a range of stream and atmospheric physical parameters including the vertical GB temperature, in an Alpine cold water stream (Oberer Seebach, Austria) over the course of a year. We found the vertical temperature profiles within the GB to vary seasonally and with discharge. We extended our study to 13 other gravel bars of varying physical characteristics within the surrounding Ybbs and Erlauf catchments, conducting diurnal spot samplings in summer 2016. Temperatures within the observed permanently wetted hyporheic zone (-56 to -100cm depth below GB surface) of the OSB, were warmer than both end members, surface water and groundwater >18% of the year, particularly during summer. There was a general increase in exceedance within the periodically wetted gravel bar sediment toward the gravel bar surface, further evidencing downward heat transfer to the wetted HZ. Average CO2 flux from the GB was significantly higher than that of streamwater during summer and winter, with significantly higher temperatures and CO2 outgassing rates occurring at the GB tail as compared to streamwater and the head and mid of the GB throughout the year. Higher cumulative (over 6 h) GB seasonal temperatures were associated with increased CO2 evasion fluxes within the OSB, particularly during summer. This enhanced CO2 flux may result from the input of warmer CO2-rich groundwater into the HZ in autumn, while downward heat transfer in summer may enhance GB metabolism and therefore

The possibility of using materials based on secondary gravel in civil construction

Directory of Open Access Journals (Sweden)

Galitskova Yulia

2017-01-01

Full Text Available By now, the wear and tear of housing stock is more than 50%. Each year the number of old and dilapidated housing is growing, but it is gradually replaced by modern buildings. However, wastes accumulated from dismantling of buildings and constructions, are underutilized and, usually are just stored at landfills, or used for temporary roads construction. The purpose of this research is to define construction wastes characteristics and to explore possibilities for recycling of wastes from construction materials production. The paper also analyzes housing stock condition and basic requirements to building materials used in construction; and demonstrates results building materials based on secondary gravel investigation. While working with materials based on waste requirements the authors conducted laboratory research. Thus, the paper presents the analysis of laboratory tests results that made it possible to draw conclusions about the possible use of building materials based on secondary gravel and about their conformity to specified requirements. The researchers also developed proposals and recommendations to improve the competitiveness of such materials.

A Laboratory Experiment on the Evolution of a Sand Gravel Reach Under a Lack of Sediment Supply

Science.gov (United States)

Orru, C.; Chavarrias, V.; Ferrara, V.; Blom, A.

2014-12-01

A flume experiment was conducted to examine the evolution of a sand-gravel reach under a lack of sediment supply. The experimental data are used to validate a numerical sand-gravel model. A bed composed of a bi-modal sediment mixture is installed with a uniform slope and an imposed gradual fining pattern. Initially, the sand fraction gradually increases in streamwise direction until the bed is fully composed of sand. The water discharge and downstream water level were constant, and the sediment feed rate was equal to zero. The experiment was dominated by bed load, partial transport, and a subcritical flow regime was imposed. The flow rate was such that only sand was mobile (partial transport), which led to a coarsening over the upstream reach and a gradual reduction of the sediment transport rate during the experiment. New equipment was used to measure the evolution of the grain size distribution of the bed surface during the experiment over the entire flume using image analysis. In the upstream reach we observed a gradual coarsening over time and the formation of an armour layer, which resulted in a more abrupt transition in grain size of the bed surface. Bed degradation increased in streamwise direction. This is due to the initial streamwise increase in the availability of sand in the bed. The different volume fraction content of sand in the bed allowed for the gravel to sink more in the downstream part of the upstream reach. The sand reach suffered from a larger degradation. Finally, we see one reach dominated by sand, small bedforms, and a small bed slope, and a gravel reach dominated by a larger bed slope.

Performance of chip seals using local and minimally processed aggregates for preservation of low traffic volume roadways.

Science.gov (United States)

2013-07-01

This report documents the performance of two low traffic volume experimental chip seals constructed using : locally available, minimally processed sand and gravel aggregates after four winters of service. The projects : were constructed by CDOT maint...

Experimental investigation on heat transport in gravel-sand materials

DEFF Research Database (Denmark)

Maureschat, Gerald; Heller, Alfred

1997-01-01

in sand-gravel material, the storage media is to be water satured. In this case, handling of such material on site is rather complex. The conduction is highly dependent on the thermal properties of the storage media and so is the overall thermal performance of a storage applying such media. For sandy...... out in a small size experiment. The experiment consists of a highly insulated box filled with two kinds of sand material crossed by a plastic heat pipe. Heat transfer is measured under dry and water satured conditions in a cross-section.The conclusions are clear. To obtain necessary heat conduction...

Injury experience in sand and gravel mining, 1991

Energy Technology Data Exchange (ETDEWEB)

1993-10-01

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

Sampling surface and subsurface particle-size distributions in wadable gravel-and cobble-bed streams for analyses in sediment transport, hydraulics, and streambed monitoring

Science.gov (United States)

Kristin Bunte; Steven R. Abt

2001-01-01

This document provides guidance for sampling surface and subsurface sediment from wadable gravel-and cobble-bed streams. After a short introduction to streams types and classifications in gravel-bed rivers, the document explains the field and laboratory measurement of particle sizes and the statistical analysis of particle-size distributions. Analysis of particle...

Experimental tests and computational fluid dynamics (CFD) helps in determination the new operational limits for gravel packing; Testes experimentais e simulacoes em fluidodinamica computacional (CFD) auxiliam na determinacao de novos limites operacionais para o gravel packing

Energy Technology Data Exchange (ETDEWEB)

Magalhaes, Joao Vicente Martins de [PETROBRAS, Santos, SP (Brazil). E e P Construcao de Pocos Maritimos. Construcao e Manutencao de Pocos], e-mail: jvmm@petrobras.com.br; Calderon, Agostinho [PETROBRAS, rj (bRAZIL). E e P Construcao de Pocos Maritimos. Construcao e Manutencao de Pocos], e-mail: agoscal@petrobras.com.br; Leal, Rafael Amorim Ferreira [Centro de Pesquisas da Petrobras (CENPES), RJ (Brazil). P e D em Geoengenharia e Engenharia de Poco. Gerencia de Perfuracao e Completacao de Pocos], e-mail: rafaelleal@petrobras.com.br; Miranda, Daniel Bonavides [Halliburton Energy Services (Brazil)], e-mail: daniel.miranda@halliburton.com; Simoes, Bruno Campos; Nunes, Mauro Jose de Souza Custodio [Halliburton Brasil. Setor de Estimulacao e Controle de Areia (Brazil)], e-mails: bruno.simoes@halliburton.com, mauro.nunes@halliburton.com; Barbosa, Diego Paiva [Halliburton Brasil. Coordenador de Servicos de Campo (Brazil)], e-mail: diego.barbosa@halliburton.com; Souza, Jairo Zago de [Engineering Simulation and Scientific Software - ESSS (Brazil)], e-mail: jairo@esss.com.br

2010-06-15

Open hole Gravel Packing was the sand control strategy adopted by PETROBRAS while developing Campos Basin fields. One of the big problems in the oil industry is based on stems from the fact of that all the whole operations are carried out many thousands of feet in the underground, without direct visualization supervision. All the controls used in the operations are based upon direct and/or indirect measurements, but without, however, the necessary visual aid. This was the motivator for the construction of an experimental device that could simulate both the open well and the rat-hole allowing the study of how the deposition of Gravel occurs around the screens. Such experimental apparatus was built with casing pipes it which common rat-hole/open-hole inside diameters (12 1/'' and 8 1/2''). For the tests representativeness the simulator was equipped with real screens and wash pipes, reproducing the real operation dynamics. In the apparatus it was possible: to see Gravel settling through acrylic windows, to test new low-cost proppants and new concentrations, to define new minimal pump operational rates, as well as to record by filming the turbulent structures that occurs at the rat-hole/open-hole contraction zone. This paper treats of these results release and show CFD results used to enlarge test matrix. (author)

Hydraulic characterisation of iron-oxide-coated sand and gravel based on nuclear magnetic resonance relaxation mode analyses

Directory of Open Access Journals (Sweden)

S. Costabel

2018-03-01

Full Text Available The capability of nuclear magnetic resonance (NMR relaxometry to characterise hydraulic properties of iron-oxide-coated sand and gravel was evaluated in a laboratory study. Past studies have shown that the presence of paramagnetic iron oxides and large pores in coarse sand and gravel disturbs the otherwise linear relationship between relaxation time and pore size. Consequently, the commonly applied empirical approaches fail when deriving hydraulic quantities from NMR parameters. Recent research demonstrates that higher relaxation modes must be taken into account to relate the size of a large pore to its NMR relaxation behaviour in the presence of significant paramagnetic impurities at its pore wall. We performed NMR relaxation experiments with water-saturated natural and reworked sands and gravels, coated with natural and synthetic ferric oxides (goethite, ferrihydrite, and show that the impact of the higher relaxation modes increases significantly with increasing iron content. Since the investigated materials exhibit narrow pore size distributions, and can thus be described by a virtual bundle of capillaries with identical apparent pore radius, recently presented inversion approaches allow for estimation of a unique solution yielding the apparent capillary radius from the NMR data. We found the NMR-based apparent radii to correspond well to the effective hydraulic radii estimated from the grain size distributions of the samples for the entire range of observed iron contents. Consequently, they can be used to estimate the hydraulic conductivity using the well-known Kozeny–Carman equation without any calibration that is otherwise necessary when predicting hydraulic conductivities from NMR data. Our future research will focus on the development of relaxation time models that consider pore size distributions. Furthermore, we plan to establish a measurement system based on borehole NMR for localising iron clogging and controlling its remediation

Efficiency of phenol biodegradation by planktonic Pseudomonas pseudoalcaligenes (a constructed wetland isolate) vs. root and gravel biofilm.

Science.gov (United States)

Kurzbaum, Eyal; Kirzhner, Felix; Sela, Shlomo; Zimmels, Yoram; Armon, Robert

2010-09-01

In the last two decades, constructed wetland systems gained increasing interest in wastewater treatment and as such have been intensively studied around the world. While most of the studies showed excellent removal of various pollutants, the exact contribution, in kinetic terms, of its particular components (such as: root, gravel and water) combined with bacteria is almost nonexistent. In the present study, a phenol degrader bacterium identified as Pseudomonas pseudoalcaligenes was isolated from a constructed wetland, and used in an experimental set-up containing: plants and gravel. Phenol removal rate by planktonic and biofilm bacteria (on sterile Zea mays roots and gravel surfaces) was studied. Specific phenol removal rates revealed significant advantage of planktonic cells (1.04 × 10(-9) mg phenol/CFU/h) compared to root and gravel biofilms: 4.59 × 10(-11)-2.04 × 10(-10) and 8.04 × 10(-11)-4.39 × 10(-10) (mg phenol/CFU/h), respectively. In batch cultures, phenol biodegradation kinetic parameters were determined by biomass growth rates and phenol removal as a function of time. Based on Haldane equation, kinetic constants such as μ(max) = 1.15/h, K(s) = 35.4 mg/L and K(i) = 198.6 mg/L fit well phenol removal by P. pseudoalcaligenes. Although P. pseudoalcaligenes planktonic cells showed the highest phenol removal rate, in constructed wetland systems and especially in those with sub-surface flow, it is expected that surface associated microorganisms (biofilms) will provide a much higher contribution in phenol and other organics removal, due to greater bacterial biomass. Factors affecting the performance of planktonic vs. biofilm bacteria in sub-surface flow constructed wetlands are further discussed. Copyright © 2010 Elsevier Ltd. All rights reserved.

Hydraulic characterisation of iron-oxide-coated sand and gravel based on nuclear magnetic resonance relaxation mode analyses

Science.gov (United States)

Costabel, Stephan; Weidner, Christoph; Müller-Petke, Mike; Houben, Georg

2018-03-01

The capability of nuclear magnetic resonance (NMR) relaxometry to characterise hydraulic properties of iron-oxide-coated sand and gravel was evaluated in a laboratory study. Past studies have shown that the presence of paramagnetic iron oxides and large pores in coarse sand and gravel disturbs the otherwise linear relationship between relaxation time and pore size. Consequently, the commonly applied empirical approaches fail when deriving hydraulic quantities from NMR parameters. Recent research demonstrates that higher relaxation modes must be taken into account to relate the size of a large pore to its NMR relaxation behaviour in the presence of significant paramagnetic impurities at its pore wall. We performed NMR relaxation experiments with water-saturated natural and reworked sands and gravels, coated with natural and synthetic ferric oxides (goethite, ferrihydrite), and show that the impact of the higher relaxation modes increases significantly with increasing iron content. Since the investigated materials exhibit narrow pore size distributions, and can thus be described by a virtual bundle of capillaries with identical apparent pore radius, recently presented inversion approaches allow for estimation of a unique solution yielding the apparent capillary radius from the NMR data. We found the NMR-based apparent radii to correspond well to the effective hydraulic radii estimated from the grain size distributions of the samples for the entire range of observed iron contents. Consequently, they can be used to estimate the hydraulic conductivity using the well-known Kozeny-Carman equation without any calibration that is otherwise necessary when predicting hydraulic conductivities from NMR data. Our future research will focus on the development of relaxation time models that consider pore size distributions. Furthermore, we plan to establish a measurement system based on borehole NMR for localising iron clogging and controlling its remediation in the gravel pack of

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

Science.gov (United States)

Peter J. Whiting; John G. King

2003-01-01

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

Sand and gravel mine operations and reclamation planning using microcomputers

Energy Technology Data Exchange (ETDEWEB)

Ariffin, J.B.

1990-02-01

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

Plant succession patterns on residual open-pit gravel mines deposits Bogota

OpenAIRE

Ricardo A. Mora Goyes

1999-01-01

Based on both: the study of composition and structure of plant communities and the analysis of the physico-chemical characteristics of mining wastes, the initial patterns of primary succession were determined. These patterns were present in three deposits of waste material abandoned during 18, 36 and 120 months respectively. Sue materials were originated in open-pit gravel mines located to the south of Bogota (Colombia). This study pretends to contribute to the knowledge of the meehanlsms of ...

Frost susceptibility of sub-base gravel used in Pearl-Chain Bridges: an experimental investigation

DEFF Research Database (Denmark)

Lund, Mia Schou Møller; Hansen, Kurt Kielsgaard; Andersen, Iben Brøndum

2016-01-01

This study investigates frost susceptibility of sub-base gravel determined by the ASTM D5918-13 standard as a conservative estimate of the frost heave risk of fill in overfilled arch bridges, particularly in Pearl-Chain Bridges. Frost heave of granular materials has been of great research interes...

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

International Nuclear Information System (INIS)

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

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

International Nuclear Information System (INIS)

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, we 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. (orig.). (7 refs., 3 figs.)

The relationship between emergence from spawning gravel and growth in farmed rainbow trout Oncorhynchus mykiss

DEFF Research Database (Denmark)

Åberg Andersson, Madelene; Laursen, Danielle Caroline; SILVA, P.I.M.

2013-01-01

The relationship between the timing of emergence from spawning gravel and growth after emergence was investigated in farmed Oncorhynchus mykiss. A relationship between the time of emergence and growth became evident after 6 months of rearing, where individuals with an intermediate emergence time...

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

Science.gov (United States)

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.

Impacts des activités d'extraction de gravier au Sud du Bénin et leur perception par la population locale

Directory of Open Access Journals (Sweden)

Aïtondji, AL.

2016-01-01

Full Text Available Impacts of gravel extraction activities in Southern Benin: Residents' perception. Gravel extraction activities in Southern Benin are carried out without formal license from the state authorities. The majority of sites are rented from landowners and located near other forms of land use including human settlements. This study aims at assessing the perception by the residents of these gravel extraction operations. The results show the social services and damages of this industry. An ordinal logit regression revealed significant influences of the respondents' ethnic group, occupation, education level, marital status and age on the perception of road infrastructure, dust pollution, loss of agricultural land and school drop-out. Therefore, it is important that the local authorities undertake mitigation actions in particular in order to prevent road dust occurrence and to restore abandoned sites so that these sites are again available for agriculture.

The morphodynamics and internal structure of intertidal fine-gravel dunes: Hills Flats, Severn Estuary, UK

Science.gov (United States)

Carling, P. A.; Radecki-Pawlik, A.; Williams, J. J.; Rumble, B.; Meshkova, L.; Bell, P.; Breakspear, R.

2006-01-01

In the macrotidal Severn estuary, UK, the dynamics of intertidal fine-gravel dunes were investigated. These dunes are migrating across a bedrock platform. Systematic observations were made of hydraulic climate, geometry, migration rates and internal sedimentary structures of the dunes. During spring tides, the ebb flow is dominant, dunes grow in height and have ebb orientated geometry with bedrock floors in the troughs. During neap tides, a weak flood flow may dominate. Dunes then are flood orientated or symmetrical. Neap dune heights decrease and the eroded sediment is stored in the dune troughs where the bedrock becomes blanketed by muddy gravel. During spring tides, instantaneous bed shear stresses reach 8 N m - 2 , sufficient to disrupt a 9 mm-gravel armour layer. However, a sustained bed shear stress of 4 N m - 2 is required to initiate dune migration at which time the critical depth-mean velocity is 1 m s - 1 . Ebb and flood inequalities in the bed shear stress explain the changes in dune asymmetry and internal structures. During flood tides, the crests of the dunes reverse such that very mobile sedimentary 'caps' overlie a more stable dune 'core'. Because ebb tides dominate, internal structures of the caps often are characterised by ebb orientated steep open-work foresets developed by strong tidal currents and some lower angle crossbeds deposited as weaker currents degrade foresets. The foresets forming the caps may be grouped into cosets (tidal bundles) and are separated from mud-infused cores of crossbeds that lie below, by reactivation and erosion surfaces blanketed by discontinuous mud drapes. The cores often exhibit distinctive muddy toe sets that define the spacing of tidal cosets.

Plant succession patterns on residual open-pit gravel mines deposits Bogota

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Ricardo A. Mora Goyes

1999-07-01

Full Text Available Based on both: the study of composition and structure of plant communities and the analysis of the physico-chemical characteristics of mining wastes, the initial patterns of primary succession were determined. These patterns were present in three deposits of waste material abandoned during 18, 36 and 120 months respectively. Sue materials were originated in open-pit gravel mines located to the south of Bogota (Colombia. This study pretends to contribute to the knowledge of the meehanlsms of natural restauration of tropical ecosystems subjected to man-borne degradation.

Bed Load Variability and Morphology of Gravel Bed Rivers Subject to Unsteady Flow: A Laboratory Investigation

Science.gov (United States)

Redolfi, M.; Bertoldi, W.; Tubino, M.; Welber, M.

2018-02-01

Measurement and estimation of bed load transport in gravel bed rivers are highly affected by its temporal fluctuations. Such variability is primarily driven by the flow regime but is also associated with a variety of inherent channel processes, such as flow turbulence, grain entrainment, and bed forms migration. These internal and external controls often act at comparable time scales, and are therefore difficult to disentangle, thus hindering the study of bed load variability under unsteady flow regime. In this paper, we report on laboratory experiments performed in a large, mobile bed flume where typical hydromorphological conditions of gravel bed rivers were reproduced. Data from a large number of replicated runs, including triangular and square-wave hydrographs, were used to build a statistically sound description of sediment transport processes. We found that the inherent variability of bed load flux strongly depends on the sampling interval, and it is significantly higher in complex, wandering or braided channels. This variability can be filtered out by computing the mean response over the experimental replicates, which allows us to highlight two distinctive phenomena: (i) an overshooting (undershooting) response of the mean bed load flux to a sudden increase (decrease) of discharge, and (ii) a clockwise hysteresis in the sediment rating curve. We then provide an interpretation of these findings through a conceptual mathematical model, showing how both phenomena are associated with a lagging morphological adaptation to unsteady flow. Overall, this work provides basic information for evaluating, monitoring, and managing gravel transport in morphologically active rivers.

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

Science.gov (United States)

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

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.

Science.gov (United States)

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

Fluvial gravel stabilization by net-spinning Hydropsychid caddisflies: exploring the magnitude and geographic scope of ecosystem engineering effect and evaluating resistance to anthropogenic stresses

Science.gov (United States)

Daniels, M.; Albertson, L.; Sklar, L. S.; Tumolo, B.; Mclaughlin, M. K.

2017-12-01

Several studies have demonstrated the substantial effects that organisms can have on earth surface processes. Known as ecosystem engineers, in streams these organisms maintain, modify, or create physical habitat structure by influencing fluvial processes such as gravel movement, fine sediment deposition and bank erosion. However, the ecology of ecosystem engineers and the magnitude of ecosystem engineering effects in a world increasingly influence by anthropogenically-driven changes is not well understood. Here we present a synthesis of research findings on the potential gravel stabilization effects of Hydropsychid caddisflies, a globally distributed group of net-spinning insects that live in the benthic substrate of most freshwater streams. Hydropsychid caddisflies act as ecosystem engineers because these silk structures can fundamentally alter sediment transport conditions, including sediment stability and flow currents. The silk nets spun by these insects attach gravel grains to one another, increasing the shear stress required to initiate grain entrainment. In a series of independent laboratory experiments, we investigate the gravel size fractions most affected by these silk attachments. We also investigate the role of anthropogenic environmental stresses on ecosystem engineering potential by assessing the impact of two common stressors, high fine sediment loads and stream drying, on silk structures. Finally, an extensive field survey of grain size and Hydropsychid caddisfly population densities informs a watershed-scale network model of Hydropsychid caddisfly gravel stabilizing potential. Our findings provide some of the first evidence that caddisfly silk may be a biological structure that is resilient to various forms of human-mediated stress and that the effects of animal ecosystem engineers are underappreciated as an agent of resistance and recovery for aquatic communities experiencing changes in sediment loads and hydrologic regimes.

A 2D hydrodynamic-sedimentological model for gravel-bed rivers. Part I: theory and validation

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Gabriel Kaless

2013-09-01

Full Text Available This paper presents a novel 2D-depth average model especially developed for gravel-bed rivers, named Lican-Leufú (Lican=pebble and Leufu=river, in Mapuche’s language, the native inhabitants of Central Patagonia, Argentina. The model consists of three components: a hydrodynamic, a sedimentological, and a morphological model. The flow of water is described by the depth-averaged Reynolds equations for unsteady, free-surface, shallow water flows. It includes the standard k-e model for turbulence closure. Sediment transport can be divided in different size classes (sand-gravel mixture and the equilibrium approach is used for Exner’s equation. The amour layer is also included in the structure of the model and the surface grain size distribution is also allowed to evolve. The model simulates bank slides that enable channel widening. Models predictions were tested against a flume experiment where a static armour layer was developed under conditions of sediment starvations and general good agreements were found: the model predicted adequately the sediment transport, grain size of transported material, final armour grain size distribution and bed elevation.

Sodium fire aerosol loading capacity of several sand and gravel filters

International Nuclear Information System (INIS)

Barreca, J.R.; McCormack, J.D.

1980-04-01

Improved specific loading capacity for sodium fire aerosols was the objective of a sand and gravel test series. The aerosol capacity and related differential pressure of eight aggregate filters is presented. A maximum specific aerosol capacity, for dry aerosol, of 2.4 kg (Na) m -2 was obtained. This filter was loaded to a final differential pressure of 2.6 kPa. The average superficial face velocity was 0.5 cm/s and the average efficiency was 99.8%. The test results indicate that filter capacity increases with aerosol moisture content and with decreasing superficial velocity

Ecosystem services provided by a former gravel extraction site in the uk under two contrasting restoration states

Directory of Open Access Journals (Sweden)

Phillip J Blaen

2016-01-01

Full Text Available Mineral extraction sites restored for nature conservation can provide areas of high quality habitat and enhance local biodiversity, yet the ecosystem services and associated socio-economic benefits delivered by such sites are not well understood. Here we use a combination of primary field data, benefit transfer, and visitor questionnaires to assess ecosystem services provided by a former gravel mining site restored for nature conservation. We quantify the marginal benefits accrued from the site by comparing ecosystem service delivery from the current nature conservation state to delivery under a highly plausible alternative restoration state; namely a public amenity park. Our results suggest restoration for nature conservation is associated with relatively high carbon storage, but that carbon sequestration is offset to some degree by greenhouse gas fluxes from saturated reed bed areas. We demonstrate through a zonal travel-cost method and individual interviews that restoration for nature conservation contributes to local amenity value by providing specialised wildlife viewing opportunities to visitors. Our results highlight the potential ecosystem services associated with mineral sites restored for nature conservation. Notably, this study strengthens the evidence base to support the case for biodiversity-focused restoration of these extraction sites, both to the minerals industry and governmental planners, by suggesting that such restoration strategies may play an important role in contributing to human well-being without impeding economic progress.

Localization of self-generated synthetic footstep sounds on different walked-upon materials through headphones

DEFF Research Database (Denmark)

Turchet, Luca; Spagnol, Simone; Geronazzo, Michele

2016-01-01

typologies of surface materials: solid (e.g., wood) and aggregate (e.g., gravel). Different sound delivery methods (mono, stereo, binaural) as well as several surface materials, in presence or absence of concurrent contextual auditory information provided as soundscapes, were evaluated in a vertical...... localization task. Results showed that solid surfaces were localized significantly farther from the walker's feet than the aggregate ones. This effect was independent of the used rendering technique, of the presence of soundscapes, and of merely temporal or spectral attributes of sound. The effect...

Wall roughness effects on flow and scouring in curved channels with gravel bed

OpenAIRE

Hersberger, Daniel S.

2002-01-01

Wall roughness effects on flow and scouring in curved channels with gravel bed In the narrow valleys in Alpine regions, rivers frequently flow across constructed zones, passing through villages and cities. Due to limited space, the protection from high floods often needs to be ensured by protection walls. During floods, these protection walls may be endangered by scour phenomena, especially if they are located in bends. In the past, the potential danger of underscoured structures was reduced ...

Field Comparisons of the Elwha Bedload Sampler and an Acoustic Gravel-transport Sensor: Middle Fork of the Piedra River, Colorado, USA

Science.gov (United States)

Downing, J.; Ryan, S. E.

2001-12-01

slope and local depth were used to calculate the velocity and momentum for each size fraction. The total momentum of coarse gravel trapped during 273 minutes of sampling per meter of bed was 16.4 kg m s-1. During the same time, the GTS measured total momentum of 14.9 kg m s-1 per meter of bed. Paired Elwha and GTS measurements for transects and single verticals are poorly correlated (r2 = 0.1 to 0.4), however, suggesting that additional samples and longer sampling times will be required to resolve cross-channel and temporal variations in transport.

Study on weathering index for improving the reliability of terrace correlation and chronology. Part 2. Understanding weathering condition of terrace gravel and induction of application requirement for correlation index

International Nuclear Information System (INIS)

Hamada, Takaomi

2012-01-01

Geomorphographic survey of fluvial terraces, geological exploration, borehole drilling and investigation, and analysis of weathering condition of terrace gravels were carried out in Chuetsu area, Niigata prefecture, where a great deal of geomorphostratigraphic and tephrostratigraphic data are available. The results of these surveys and investigations indicate that weathering degree of terrace gravels can be considered as an index of the terrace age, and also provide points to remember for sampling and method of sampling and observation. The effective porosity and the thickness of weathering rind of gravels, which are indexes for weathering degree evaluation, in boring core, increase above the depth of about 5m from the top of the hole. Weathering doesn't reach the deep portion, therefore, investigation and evaluation for the weathering degree of terrace gravels must be carried out on the upper portion. Weathering rind thickness and effective porosity of the gravels are dispersive. Dispersion of the weathering rind thickness can be reduced by confining to andesite, and dispersion of the effective porosity can be reduced by limiting range of gravel size. Reducing dispersion, increase trend with age becomes clear in change of the weathering rind thickness and the effective porosity in many of the studied area. It shows that weathering rind thickness and effective porosity are effective for terrace correlation. Dispersion of data in an outcrop isn't small, but data from neighboring terraces with the same age are not different each other. It indicates that weathering rind thickness and effective porosity can be quantitative indexes for terrace age evaluation. In area where weathering rind is effective for terrace correlation, the rate of the weathering rind formation of andesite gravels is about 0.04mm/1000 years. Therefore, MIS6 terraces and MIS8 terraces can be distinguished each other by means of thickness of the weathering rind. This formation rate falls inside the

Instream sand and gravel mining: Environmental issues and regulatory process in the United States

Science.gov (United States)

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.

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

Science.gov (United States)

Todd, B.J.; Valentine, Page C.; Harris, Peter T; Baker, E.K.

2012-01-01

Georges Bank is a large, shallow, continental shelf feature offshore of New England and Atlantic Canada. The bank is mantled with a veneer of glacial debris transported during the late Pleistocene from continental areas lying to the north. These sediments were reworked by marine processes during postglacial sea-level transgression and continue to be modified by the modern oceanic regime. The surficial geology of the Canadian portion of the bank is a widespread gravel lag overlain in places by well sorted sand occurring as bedforms. The most widespread bedforms are large, mobile, asymmetrical sand waves up to 19 m in height formed through sediment transport by strong tidal-driven and possibly storm-driven currents. Well-defined curvilinear bedform crests up to 15 km long form a complex bifurcating pattern having an overall southwest–northeast strike, which is normal to the direction of the major axis of the semidiurnal tidal current ellipse. Minor fields of immobile, symmetrical sand waves are situated in bathymetric lows. Rare mobile, asymmetrical barchan dunes are lying on the gravel lag in areas of low sand supply. On Georges Bank, the management of resources and habitats requires an understanding of the distribution of substrate types, their surface dynamics and susceptibility to movement, and their associated fauna.

Soil erosion rates from mixed soil and gravel surfaces in a wind tunnel: A preliminary report

International Nuclear Information System (INIS)

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

The timing of scour and fill in a gravel-bedded river measured with buried accelerometers

Science.gov (United States)

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.

The influence of sediment transport rate on the development of structure in gravel bed rivers

Science.gov (United States)

Ockelford, Annie; Rice, Steve; Powell, Mark; Reid, Ian; Nguyen, Thao; Tate, Nick; Wood, Jo

2013-04-01

Although adjustments of surface grain size are known to be strongly influenced by sediment transport rate little work has systematically explored how different transport rates can affect the development of surface structure in gravel bed rivers. Specifically, it has been well established that the transport of mixed sized sediments leads to the development of a coarser surface or armour layer which occurs over larger areas of the gravel bed. Armour layer development is known to moderate overall sediment transport rate as well as being extremely sensitive to changes in applied shear stress. However, during this armouring process a bed is created where, smaller gain scale changes, to the bed surface are also apparent such as the development of pebble clusters and imbricate structures. Although these smaller scale changes affect the overall surface grain size distribution very little their presence has the ability to significantly increase the surface stability and hence alter overall sediment transport rates. Consequently, the interplay between the moderation of transport rate as a function of surface coarsening at a larger scale and moderation of transport rate as a function of the development of structure on the bed surface at the smaller scale is complicated and warrants further investigation. During experiments a unimodal grain size distribution (σg = 1.30, D50 = 8.8mm) was exposed to 3 different levels of constant discharge that produced sediment transport conditions ranging from marginal transport to conditions approaching full mobility of all size fractions. Sediment was re-circulated during the experiments surface grain size distribution bed load and fractional transport rates were measured at a high temporal resolution such that the time evolution of the beds could be fully described. Discussion concentrates on analysing the effects of the evolving bed condition sediment transport rate (capacity) and transported grain size (competence). The outcome of this

Alternatives to conventional gravel wearing courses on low volume rural roads: Phase 1

CSIR Research Space (South Africa)

Paige-Green, P

2003-01-01

Full Text Available Adviser Abstract Gundo Lashu, the ‘Labour Intensive Rural Roads Maintenance Programme’ that is currently being implemented in Limpopo Province, South Africa has set out to train 24 emerging contractors in rehabilitation of rural gravel roads. All.... The proposal is to treat the in situ materials and sand with a diluted emulsion and a nominal cement application (to assist with breaking of the emulsion) and surface the road with an Otta seal. The aggregate for the Otta seal can be obtained form...

The Mobility and Dispersal of Augmented Gravel in Upland Channels: a Knowledge-limited Practise in Supply-limited Channels

Science.gov (United States)

Downs, P. W.; Gilvear, D. J.

2017-12-01

Most river restoration research has been directed at rivers in the highly populated alluvial lowlands: significantly less is known about effectively rehabilitating upland channels, in part because the dynamics of sediment transfer are less well understood. Upland gravel augmentation is thus both a somewhat unproven method for rehabilitating degraded aquatic habitats in sediment-poor reaches, but also a natural experiment in better understanding sediment dynamics in steep, hydraulically-complex river channels. Monitoring on the River Avon in SW England since Water Year (WY) 2015 uses seismic impact plates, RFID-tagged particles and detailed channel bed mapping to establish the mobility rates of augmented particles, their dispersal distances and settling locations relative to flows received. Particles are highly, and equally, mobile: in WY2015, 17 sub-bankfull flows moved at least 60% of augmented particles with volumetric movement non-linearly correlated to flow energy but not to particle size. Waning rates of transport over the year suggest supply limitations. This relationship breaks down early in WY2017 where a two-year flow event moved 40% of the particles in just two months - confounding factors may include particle mass differences and particle supplies from upstream. Median particle travel distances correlate well to energy applied and suggest a long-tailed fan of dispersal with supplemental controls including channel curvature, boulder presence and stream power. Locally, particles are deposited preferentially around boulders and in sheltered river margins but also perched in clusters above the low-flow channel. High tracer mobility makes median transport distances highly dependent on the survey length - in WY2017 some particles travelled 300 m in a 3-month period that included the two-year flood event. Further, in WY2017 median transport distance as a function of volumetric transport suggested significant transport beyond the target reach. The observed

The relative contribution of near-bed vs. intragravel horizontal transport to fine sediment accumulation processes in river gravel beds

Science.gov (United States)

Casas-Mulet, Roser; Lakhanpal, Garima; Stewardson, Michael J.

2018-02-01

Understanding flow-sediment interactions is important for comprehending river functioning. Fine sediment accumulation processes, in particular, have key implications for ecosystem health. However, the amount of fines generated by intragravel flows and later accumulated in gravel streambeds may have been underestimated, as the hydraulic-related driving transport mechanisms in play are not clearly identified. Specifically, the relative contribution of fines from upper vs. lower sediment layers in gravel beds is not well understood. By recreating flooded and dewatered conditions in an experimental flume filled with natural sediment, we estimated such contributions by observing and collecting intragravel transported fines that were later accumulated into a void in the middle of the sediment matrix. Near-bed transport in the upper sediment layers (named Brinkman load) during flooded conditions accounted for most (90%) of the accumulated fines. Intragravel transport in the lower sediment layers (named Interstitial load) was the sole source of transport and accumulation during dewatered conditions with steeper hydraulic gradients. Interstitial load accounted for 10% of the total transport during flooded conditions. Although small, such estimations demonstrate that hydraulic-gradient transport in the lower sediment layers occurs in spite of the contradicting analytical assessments. We provide a case study to challenge the traditional approaches of assessing intragravel transport, and a useful framework to understand the origin and relative contribution of fine sediment accumulation in gravel beds. Such knowledge will be highly useful for the design of monitoring programs aiding river management, particularly in regulated rivers.

Towards an increase of flash flood geomorphic effects due to gravel mining and ground subsidence in Nogalte stream (Murcia, SE Spain

Directory of Open Access Journals (Sweden)

J. A. Ortega-Becerril

2016-10-01

Full Text Available Transition from endorheic alluvial fan environments to well-channelized fluvial systems in natural conditions may occur in response to base-level fluctuations. However, human-induced changes in semi-arid regions can also be responsible for similar unforeseen modifications. Our results confirm that in-channel gravel mining and aquifer overexploitation over the last 50 years in the case study area have changed the natural stability of the Nogalte stream and, as a result, its geomorphic parameters including channel depth and longitudinal profile have begun to adapt to the new situation. Using interferometric synthetic aperture radar (InSAR data we obtain maximum values for ground subsidence in the Upper Guadalentín Basin of  ∼ 10 cm yr−1 for the period 2003–2010. In this context of a lowered base level, the river is changing its natural flood model to a more powerful one. A comparison of the 1973 flood event, the most dramatic flood event ever recorded in the area, with the 2012 event, where there was a similar discharge but a sediment load deficit, reveals greater changes and a new flooding pattern and extension. In-channel gravel mining may be responsible for significant local changes in channel incision and profile. This, together with the collateral effects of aquifer overexploitation, can favour increased river velocity and stream power, which intensify the consequences of the flooding. The results obtained here clearly demonstrate an existing transition from the former alluvial pattern to a confined fluvial trend, which may become more pronounced in the future due to the time lag between the drop in aquifer level and ground subsidence, and introduce a new scenario to be taken into consideration in future natural hazard planning in this area.

Flow structure through pool-riffle sequences and a conceptual model for their sustainability in gravel-bed rivers

Science.gov (United States)

D. Caamano; P. Goodwin; J. M. Buffington

2010-01-01

Detailed field measurements and simulations of three-dimensional flow structure were used to develop a conceptual model to explain the sustainability of self-formed pool-riffle sequences in gravel-bed rivers. The analysis was conducted at the Red River Wildlife Management Area in Idaho, USA, and enabled characterization of the flow structure through two consecutive...

Bed stability in unconfined gravel bed mountain streams: With implications for salmon spawning viability in future climates

Science.gov (United States)

Jim McKean; Daniele Tonina

2013-01-01

Incubating eggs of autumn-spawning Chinook salmon (Oncorhynchus tshawytscha) could be at risk of midwinter high flows and substrate scour in a changing climate. A high-spatial-resolution multidimensional hydrodynamics model was used to assess the degree of scour risk in low-gradient unconfined gravel bed channels that are the favored environment for autumn-spawning...

Effects of gravel mulch on soil hydro-thermal process and rain-fed wheat-maize yields%砾石覆盖对土壤水热过程及旱作小麦玉米产量的影响

Institute of Scientific and Technical Information of China (English)

王冬林; 冯浩; 李毅

2017-01-01

为了揭示砾石覆盖对农田土壤水热变化及作物产量形成的影响,2013—2015年采用小区试验法研究冬小麦-夏玉米轮作条件下土壤水分变化、温度效应以及作物生长和产量之间的相互作用关系.田间试验设置无覆盖(CK)、25%砾石覆盖(GM1)、50%砾石覆盖(GM2)、75%砾石覆盖(GM3)和100%砾石覆盖(GM4)5个处理.结果表明:砾石覆盖度与土壤水分呈显著正相关,100%砾石覆盖处理土壤贮水量最高;干旱胁迫条件下砾石覆盖度越高土壤的保水性越好,降雨条件下砾石覆盖度越高土壤截留雨水的能力越大.砾石覆盖具有明显的增温效应,4个砾石覆盖处理的土壤平均温度大于CK处理,GM4处理土壤平均温度最大;砾石覆盖处理可以认为是一种有效的温度调节方式,具体表现在低温(?5~0℃)条件下GM4处理较CK处理土壤温度增加5℃,高温(40~45℃)条件下GM4处理较CK处理土壤温度降低3.7℃;在寒冷气候和水分亏缺的情况下4个砾石覆盖处理增温能力均大于对照.此外,夏玉米叶面积指数随着砾石覆盖度增加而增大.100%砾石覆盖处理的2季冬小麦和夏玉米平均产量较对照处理分别增加了58.55%和22.50%.可见,砾石覆盖技术可以有效保持土壤水分、增加土壤温度、促进作物生长和提高产量,是干旱半干旱地区应对水分胁迫和气候变化、实现农业增产的有效途径.%Rain-fed farming in semi-arid areas of the Loess Plateau in China is constrained by low temperatures and water limitations at the early crop growth stage, and the gravel mulch technology as an effective strategy has been used for centuries to conserve soil water and increase soil temperature. To reveal the effects of gravel mulch on soil moisture, soil temperature, rain-fed crop growth as well as yield, a field study of consecutive wheat-maize rotation was conducted in Shannxi Province in the year of 2013-2015. The field experiment was

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

Directory of Open Access Journals (Sweden)

S. D. Marks

1997-01-01

Full Text Available 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.

EVALUATION OF THE INITIAL TREE COMMUNITY ESTABBLISHED ON A GRAVEL MINE IN THE BRAZILIAN FEDERAL DISTRICT

Directory of Open Access Journals (Sweden)

Raquel Álvares Leão

2005-05-01

Full Text Available Mining activities for urbanization purposes have been practiced in the BrazilianFederal District for the last fifty years. Exploitation of sand, clay, stones, calcareous rocks,and gravel deposits resulted in 0.6% of the territory degraded by mining. Deposits explored inthe last ten years have been reclaimed as demanded by local laws.The natural restoration of areas degraded by mining explotation is unpraticable,because the seed-bed and seedlings-bed is very injuried. Also the superficial layers of soil aretaken off, causing loss of microorganism like fungi, which contributes for environmental’squality improvement for the vegetation reestablishment (Vargas & Hungria, 1997.Fortunatelly, environmental laws oblige miners to replace these superficial layers of soil(CREA-DF Cursos, 2004.The recovering of a degradaded area doesn’t necessarily mean restoration. Restorationonly happens when the damage is minimal, for example, a glade opened by the death of a tree(Fonseca et al., 2001. When an area is hardly damaged, the vegetal climax community,resulting from secondary succession, will never be the same as the one standed there before(CREA-DF Cursos, 2004; Fonseca et al., 2001. In the case of areas degraded by mining,human intervention is necessary, because the vegetation has lost its resilience, and is not ableto commence a secondary succession by itself.

The diagnosis of old gravel aspiration in adults by MDCT: a case report

Energy Technology Data Exchange (ETDEWEB)

Kim, Mi Young; Lee, Ki Yeol; Seo, Bo Kyoung; Kim, Je Hyeong; Jung, Ki Hwan [Ansan Hospital, Korea University Medical Center, Ansan (Korea, Republic of)

2008-03-15

We report a case of old gravel aspiration in a 57-year-old man who had been accidentally buried in a field of construction for ten hours, three years prior. A chest radiograph showed peribronchial pneumonic infiltrates in the right lower lobe, with a proximal ovoid radiopaque endobronchial density at the trunchus basalis. These findings were more clearly visualized on the 64-channel multidetector CT (MDCT). Moreover, the patient recovered from his condition, following a bronchoscopic retrieval. However, the patient had persistent bronchiectasis of the right lower lobe on a subsequent follow-up chest radiograph, one month later.

A 2D hydrodynamic-sedimentological model for gravel-bed rivers. Part I: theory and validation

OpenAIRE

Gabriel Kaless; Mario A. Lenzi; Luca Mao

2013-01-01

This paper presents a novel 2D-depth average model especially developed for gravel-bed rivers, named Lican-Leufú (Lican=pebble and Leufu=river, in Mapuche’s language, the native inhabitants of Central Patagonia, Argentina). The model consists of three components: a hydrodynamic, a sedimentological, and a morphological model. The flow of water is described by the depth-averaged Reynolds equations for unsteady, free-surface, shallow water flows. It includes the standard k-e model for turbulence...

Comparison of Machine Learning methods for incipient motion in gravel bed rivers

Science.gov (United States)

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

Experiences made with tritium-containing water used as tracer in laboratory experiments with fluvioglacial gravels

International Nuclear Information System (INIS)

Klotz, D.; Rauert, W.

1982-01-01

Batch tests performed on 11 different Bavarian fluvioglacial gravels led to tritium distribution coefficients, which deviated not or only insignificantly from zero within the range of experimental accuracy applied to routine testings. The result of nine flow experiments in a gravelfilled column was a mean retardation factor of 1.01 +- 0.01. These experiments thus showed - as it had been expected - that 3 HHO is not significantly delayed with regard to the flow or movement of the water. (orig.) [de

The influence of flow-through saline gravel pit lakes on the hydrologic budget and hydrochemistry of a Mediterranean drainage basin

NARCIS (Netherlands)

Mollema, P.N.; Antonellini, Marco; Dinelli, Enrico; Greggio, Nicolas; Stuijfzand, Pieter

2015-01-01

Flow-through brackish gravel pit lakes near the Adriatic Coast of Emilia Romagna (Italy) in the Mediterranean have a large influence on the hydrologic budget of the watershed. Strong evaporation in combination with intense drainage of the low lying basins enhances groundwater inflow into the

Recovering byproduct heavy minerals from sand and gravel, placer gold, and industrial mineral operations

Energy Technology Data Exchange (ETDEWEB)

Gomes, J.M.; Martinez, G.M.; Wong, M.M.

1979-01-01

The Bureau of Mines, as part of an effort to maximize minerals and metals recovery from domestic resources, has investigated the feasibility of recovering heavy minerals as byproducts from sand and gravel, placer gold, and industrial mineral operations in northern California. Sand samples from about 50 locations were treated by gravity separation to yield heavy-mineral cocentrates (black sands). Mineral compositions of the concentrates were determined by chemical analysis and mineralogical examination. Individual zircon, ilmenite, magnetite, platinum-group metals, thoria, and silica products were prepared from heavy-mineral concentrates by selective separation using low- and high-intensity magnetic, high-tension, and flotation equipment.

Application of ELJ to create and maintain side channels in a dynamic gravel bed river

Science.gov (United States)

Crabbe, E.; Crowe Curran, J.; Ockelford, A.

2017-12-01

Braided and anastomosing rivers create and maintain a large amount of side channel habitat. Unfortunately, many rivers that were once multi-channel rivers have been constrained to single thread channels as a consequence of land use changes that occurred in the 19th and 20th centuries or earlier. An increasingly common management goal today is the re-creation of self-maintaining side and tributary habitat through as natural means as possible. This work examines the geomorphic history of one such channel and the success of recent rehabilitation efforts. Our case study comes from the South Fork Nooksack River in the Cascades Range in Washington State. The Nooksack River is a gravel and sand bed channel with a snowmelt dominated hydrograph. Engineered log jams (ELJ) have been employed to direct flow into side and chute channels with the larger goals of increasing overall channel complexity and salmon spawning opportunities. ELJs have been constructed on the channel since the 2000s, and the ELJs in the study reaches range in age up to 10 years. The size and design of individual jams within the reach vary, enabling a comparison between jam types. ELJs are evaluated for their ability to maintain gravel bar locations and open tributary channels through the snowmelt season over the reach scale. Additional goals of trapping wood onto the jams and existing bars, stabilizing channel banks, and allowing for the growth of bar vegetation are also examined.

Experimental and Numerical Study of Bottom Rack Occlusion by Flow with Gravel-Sized Sediment. Application to Ephemeral Streams in Semi-Arid Regions

Directory of Open Access Journals (Sweden)

Luis G. Castillo

2016-04-01

Full Text Available Rainfall runoff collection in ephemeral streams is an objective in semi-arid zones. Rack intake systems are proposed to collect these flash floods with intensive sediment transport. The design parameters address the problem of clogging the spacing between bars. Experiments for two different void ratio racks are shown. Flows, longitudinal slopes in the rack, and water with three gravel-sized sediments were tested. Results such as effective void ratio due to the gravel deposition over the rack, the evolution of the flow rejected during each test, and the quantification of materials collected and deposited, are presented. The optimal longitudinal rack slope seems to be close to 30%. The effective void ratio is related to several hydraulic parameters calculated at the beginning of the rack. Some adjustments were proposed to predict the effective void ratio.

Mechanisms of Cottonwood Establishment in Gravel-Bed Rivers, across Scales from the Bar to the Reach

Science.gov (United States)

Meier, C. I.

2017-12-01

Riparian cottonwoods are pioneer trees adapted to colonizing fluvial corridors, with strong effects on ecosystem structure and function. As their populations are being affected by flow alterations and invasive species, their recruitment mechanisms need to be understood, to support scientifically-based restoration efforts. I propose new concepts for cottonwood establishment in gravelly streams, from the local to the reach scale. These notions complement the currently-accepted ideas, which apply only to the landscape scale, and whose basic assumptions (existence of an alluvial water table, which is planar, almost horizontal, and linked to the river stage, with a parallel, spatially-uniform capillary fringe) seem to be based on a physical template that is only valid in the case of sand-bed streams. At the local, within-the-bar scale, two concepts drive establishment success. First, a finer matrix material helps retain more capillary water after the yearly snowmelt flood or a precipitation event. Second, the coarse surface layer of clean gravel and cobble acts as rock mulch, strongly decreasing evaporative losses. At the reach scale, we find that the commonly reported arcuate bands of cottonwoods do not depend on groundwater, but are caused by water dispersal (hydrochory). Wind-dispersed seeds fall into the river, are entrained into the drift, and start germinating as they travel under water. Some of the seeds and germinants find their way into the shallow, high relative roughness flow along the cobble shoreline. They are able to deposit in this environment, where they start growing, also under water. As waters recede, during the period of seed availability in the drift, the river seeds its banks and bars. Thus, the boundaries of observed bands and patches with successful seedling recruitment correspond to the location of flow profiles at different dates during the flood recession.

Quantification of Gravel Rural Road Sediment Production

Science.gov (United States)

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.

Variability of bed mobility in natural, gravel-bed channels and adjustments to sediment load at local and reach scales

Science.gov (United States)

Thomas E. Lisle; Jonathan M. Nelson; John Pitlick; Mary Ann Madej; Brent L. Barkett

2000-01-01

Abstract - Local variations in boundary shear stress acting on bed-surface particles control patterns of bed load transport and channel evolution during varying stream discharges. At the reach scale a channel adjusts to imposed water and sediment supply through mutual interactions among channel form, local grain size, and local flow dynamics that govern bed mobility...

Temporal and spatial variability in thalweg profiles of a gravel-bed river

Science.gov (United States)

Madej, Mary Ann

1999-01-01

This study used successive longitudinal thalweg profiles in gravel-bed rivers to monitor changes in bed topography following floods and associated large sediment inputs. Variations in channel bed elevations, distributions of residual water depths, percentage of channel length occupied by riffles, and a spatial autocorrelation coefficient (Moran's I) were used to quantify changes in morphological diversity and spatial structure in Redwood Creek basin, northwestern California. Bed topography in Redwood Creek and its major tributaries consists primarily of a series of pools and riffles. The size, frequency and spatial distribution of the pools and riffles have changed significantly during the past 20 years. Following large floods and high sediment input in Redwood Creek and its tributaries in 1975, variation in channel bed elevations was low and the percentage of the channel length occupied by riffles was high. Over the next 20 years, variation in bed elevations increased while the length of channel occupied by riffles decreased. An index [(standard deviation of residual water depth/bankfull depth) × 100] was developed to compare variations in bed elevation over a range of stream sizes, with a higher index being indicative of greater morphological diversity. Spatial autocorrelation in the bed elevation data was apparent at both fine and coarse scales in many of the thalweg profiles and the observed spatial pattern of bed elevations was found to be related to the dominant channel material and the time since disturbance. River reaches in which forced pools dominated, and in which large woody debris and bed particles could not be easily mobilized, exhibited a random distribution of bed elevations. In contrast, in reaches where alternate bars dominated, and both wood and gravel were readily transported, regularly spaced bed topography developed at a spacing that increased with time since disturbance. This pattern of regularly spaced bed features was reversed

Topographical change caused by moderate and small floods in a gravel bed ephemeral river - a depth-averaged morphodynamic simulation approach

Science.gov (United States)

Lotsari, Eliisa S.; Calle, Mikel; Benito, Gerardo; Kukko, Antero; Kaartinen, Harri; Hyyppä, Juha; Hyyppä, Hannu; Alho, Petteri

2018-03-01

In ephemeral rivers, channel morphology represents a snapshot at the end of a succession of geomorphic changes caused by floods. In most cases, the channel shape and bedform migration during different phases of a flood hydrograph cannot be identified from field evidence. This paper analyses the timing of riverbed erosion and deposition of a gravel bed ephemeral river channel (Rambla de la Viuda, Spain) during consecutive and moderate- (March 2013) and low-magnitude (May 2013) discharge events, by applying a morphodynamic model (Delft3D) calibrated with pre- and post-event surveys by RTK-GPS points and mobile laser scanning. The study reach is mainly depositional and all bedload sediment supplied from adjacent upstream areas is trapped in the study segment forming gravel lobes. Therefore, estimates of total bedload sediment mass balance can be obtained from pre- and post-field survey for each flood event. The spatially varying grain size data and transport equations were the most important factors for model calibration, in addition to flow discharge. The channel acted as a braided channel during the lower flows of the two discharge events, but when bars were submerged in the high discharges of May 2013, the high fluid forces followed a meandering river planform. The model results showed that erosion and deposition were in total greater during the long-lasting receding phase than during the rising phase of the flood hydrographs. In the case of the moderate-magnitude discharge event, deposition and erosion peaks were predicted to occur at the beginning of the hydrograph, whereas deposition dominated throughout the event. Conversely, the low-magnitude discharge event only experienced the peak of channel changes after the discharge peak. Thus, both type of discharge events highlight the importance of receding phase for this type of gravel bed ephemeral river channel.

Using Pneumatics to Perform Laboratory Hydraulic Conductivity Tests on Gravel with Underdamped Responses

Science.gov (United States)

Judge, A. I.

2011-12-01

A permeameter has been designed and built to perform laboratory hydraulic conductivity tests on various kinds of gravel samples with hydraulic conductivity values ranging from 0.1 to 1 m/s. The tests are commenced by applying 200 Pa of pneumatic pressure to the free surface of the water column in a riser connected above a cylinder that holds large gravel specimens. This setup forms a permeameter specially designed for these tests which is placed in a barrel filled with water, which acts as a reservoir. The applied pressure depresses the free surface in the riser 2 cm until it is instantly released by opening a ball valve. The water then flows through the base of the cylinder and the specimen like a falling head test, but the water level oscillates about the static value. The water pressure and the applied air pressure in the riser are measured with vented pressure transducers at 100 Hz. The change in diameter lowers the damping frequency of the fluctuations of the water level in the riser, which allows for underdamped responses to be observed for all tests. The results of tests without this diameter change would otherwise be a series of critically damped responses with only one or two oscillations that dampen within seconds and cannot be evaluated with equations for the falling head test. The underdamped responses oscillate about the static value at about 1 Hz and are very sensitive to the hydraulic conductivity of all the soils tested. These fluctuations are also very sensitive to the inertia and friction in the permeameter that are calculated considering the geometry of the permeameter and verified experimentally. Several gravel specimens of various shapes and sizes are tested that show distinct differences in water level fluctuations. The friction of the system is determined by calibrating the model with the results of tests performed where the cylinder had no soil in it. The calculation of the inertia in the response of the water column for the typical testing

The effects of flooding disturbance on the distribution and behaviour of riparian arthropods along a lowland gravel river

OpenAIRE

Lambeets, Kevin

2009-01-01

This Ph.D.-thesis aimed to address which environmental factors influence the assemblage structure of mobile, riparian arthropods along spatially structured river banks of a rain-fed, lowland gravel river, the Common Meuse. As riverine ecosystems are basically non-equilibrium, dynamic ecosystems, mainly flow regimes and flood pulse characteristics are expected to shape both the distribution and behaviour of its inhabitants. The river banks along the Common Meuse are (in)frequently disturbed by...

Using UAS optical imagery and SfM photogrammetry to characterize the surface grain size of gravel bars in a braided river (Vénéon River, French Alps)

Science.gov (United States)

Vázquez-Tarrío, Daniel; Borgniet, Laurent; Liébault, Frédéric; Recking, Alain

2017-05-01

This paper explores the potential of unmanned aerial system (UAS) optical aerial imagery to characterize grain roughness and size distribution in a braided, gravel-bed river (Vénéon River, French Alps). With this aim in view, a Wolman field campaign (19 samples) and five UAS surveys were conducted over the Vénéon braided channel during summer 2015. The UAS consisted of a small quadcopter carrying a GoPro camera. Structure-from-Motion (SfM) photogrammetry was used to extract dense and accurate three-dimensional point clouds. Roughness descriptors (roughness heights, standard deviation of elevation) were computed from the SfM point clouds and were correlated with the median grain size of the Wolman samples. A strong relationship was found between UAS-SfM-derived grain roughness and Wolman grain size. The procedure employed has potential for the rapid and continuous characterization of grain size distribution in exposed bars of gravel-bed rivers. The workflow described in this paper has been successfully used to produce spatially continuous grain size information on exposed gravel bars and to explore textural changes following flow events.

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

Science.gov (United States)

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 (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 between 2001 and 2015. Our monitoring period covered a series of floods with recurrence intervals of 2 to 4 times per year, as well as one large flood with a 10 year return period. Only the

Topographical change caused by moderate and small floods in a gravel bed ephemeral river – a depth-averaged morphodynamic simulation approach

Directory of Open Access Journals (Sweden)

E. S. Lotsari

2018-03-01

Full Text Available In ephemeral rivers, channel morphology represents a snapshot at the end of a succession of geomorphic changes caused by floods. In most cases, the channel shape and bedform migration during different phases of a flood hydrograph cannot be identified from field evidence. This paper analyses the timing of riverbed erosion and deposition of a gravel bed ephemeral river channel (Rambla de la Viuda, Spain during consecutive and moderate- (March 2013 and low-magnitude (May 2013 discharge events, by applying a morphodynamic model (Delft3D calibrated with pre- and post-event surveys by RTK-GPS points and mobile laser scanning. The study reach is mainly depositional and all bedload sediment supplied from adjacent upstream areas is trapped in the study segment forming gravel lobes. Therefore, estimates of total bedload sediment mass balance can be obtained from pre- and post-field survey for each flood event. The spatially varying grain size data and transport equations were the most important factors for model calibration, in addition to flow discharge. The channel acted as a braided channel during the lower flows of the two discharge events, but when bars were submerged in the high discharges of May 2013, the high fluid forces followed a meandering river planform. The model results showed that erosion and deposition were in total greater during the long-lasting receding phase than during the rising phase of the flood hydrographs. In the case of the moderate-magnitude discharge event, deposition and erosion peaks were predicted to occur at the beginning of the hydrograph, whereas deposition dominated throughout the event. Conversely, the low-magnitude discharge event only experienced the peak of channel changes after the discharge peak. Thus, both type of discharge events highlight the importance of receding phase for this type of gravel bed ephemeral river channel.

Transport and storage of bed material in a gravel-bed channel during episodes of aggradation and degradation: a field and flume study

Science.gov (United States)

Bonnie Smith Pryor; Thomas Lisle; Diane Sutherland Montoya; Sue Hilton

2011-01-01

The dynamics of sediment transport capacity in gravel-bed rivers is critical to understanding the formation and preservation of fluvial landforms and formulating sediment-routing models in drainage systems. We examine transport-storage relations during cycles of aggradation and degradation by augmenting observations of three events of channel aggradation and...

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

Science.gov (United States)

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.

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

Science.gov (United States)

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.

Synthesis of AL-MCM-41 using gravel drilling the source of silica from wells drilling; Sintese do AL-MCM-41 usando como fonte de silica o cascalho de perfuracao de pocos de petroleo

Energy Technology Data Exchange (ETDEWEB)

Fontes, M.S.B.; Costa, C.C.; Melo, D.M.A.; Viana, L.M.; Viana, S.O.; Santos, L.M., E-mail: socorro.fontes@Yahoo.com.br [Universidade Federal do Rio grande do Norte (UFRN), Natal, RN (Brazil)

2016-07-01

The aim of this study was to synthesize Al-MCM-41 using gravel drilling as alternative source of silica, aiming at sustainable production and low cost. For hydrothermal synthesis of Al-MCM-41 was used gravel and sodium silicate as source of silica and sodium, respectively. The structural driver used was cetyltrimethylammonium bromide (CTMABr) and solvent distilled water. The hydrothermal synthesis was conducted at 100 ° C in a Teflon autoclave 45 ml jacketed stainless steel for a period of 120 hours with daily correcting pH (range 9-10) using 30% acetic acid. The material obtained was filtered, washed, dried at 100 ° C for 3 hours and then calcined at 550 ° C for 2 hours. Then it was characterized by XRD, FTIR and TG. For the results of characterization has been observed that the use of the gravel drilling as a source of silica was promising alternative for producing a mesoporous material with a high degree of hexagonal ordering. (author)

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

Science.gov (United States)

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.

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

Science.gov (United States)

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.

A new approach to define surface/sub-surface transition in gravel beds

Science.gov (United States)

Haynes, Heather; Ockelford, Anne-Marie; Vignaga, Elisa; Holmes, William

2012-12-01

The vertical structure of river beds varies temporally and spatially in response to hydraulic regime, sediment mobility, grain size distribution and faunal interaction. Implicit are changes to the active layer depth and bed porosity, both critical in describing processes such as armour layer development, surface-subsurface exchange processes and siltation/ sealing. Whilst measurements of the bed surface are increasingly informed by quantitative and spatial measurement techniques (e.g., laser displacement scanning), material opacity has precluded the full 3D bed structure analysis required to accurately define the surface-subsurface transition. To overcome this problem, this paper provides magnetic resonance imaging (MRI) data of vertical bed porosity profiles. Uniform and bimodal (σ g = 2.1) sand-gravel beds are considered following restructuring under sub-threshold flow durations of 60 and 960 minutes. MRI data are compared to traditional 2.5D laser displacement scans and six robust definitions of the surface-subsurface transition are provided; these form the focus of discussion.

Roughness coefficient and its uncertainty in gravel-bed river

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Ji-Sung Kim

2010-06-01

Full Text Available Manning's roughness coefficient was estimated for a gravel-bed river reach using field measurements of water level and discharge, and the applicability of various methods used for estimation of the roughness coefficient was evaluated. Results show that the roughness coefficient tends to decrease with increasing discharge and water depth, and over a certain range it appears to remain constant. Comparison of roughness coefficients calculated by field measurement data with those estimated by other methods shows that, although the field-measured values provide approximate roughness coefficients for relatively large discharge, there seems to be rather high uncertainty due to the difference in resultant values. For this reason, uncertainty related to the roughness coefficient was analyzed in terms of change in computed variables. On average, a 20% increase of the roughness coefficient causes a 7% increase in the water depth and an 8% decrease in velocity, but there may be about a 15% increase in the water depth and an equivalent decrease in velocity for certain cross-sections in the study reach. Finally, the validity of estimated roughness coefficient based on field measurements was examined. A 10% error in discharge measurement may lead to more than 10% uncertainty in roughness coefficient estimation, but corresponding uncertainty in computed water depth and velocity is reduced to approximately 5%. Conversely, the necessity for roughness coefficient estimation by field measurement is confirmed.

Characteristics of the gravel size and potassium in the Ejin Alluvial Fan from remote sensing images and stratigraphic section

International Nuclear Information System (INIS)

Zhang, Lu; Guo, Huadong; Wang, Qinjun

2014-01-01

The Ejin Alluvial Fan (EAF), located in the north-west of China, is an important recorder of both paleoclimatic and tectonic information of the north margin of the Qinghai-Tibet Plateau. Remote sensing technics, including optical and microwave sensors, have been the key spatial observation tools to extract the surface information related to the paleoenvironment. In this paper, the gravel size and chemical element potassium K distributions of the EAF were obtained from RadarSat-2 Synthetic Aperture Radar (SAR) data and LandSat TM optical data, respectively. In addition, the stratigraphic section of the EAF was established and the corresponding geological information in the vertical direction with different periods was obtained. Combining the geological survey information and surface distribution information, it can be concluded as follows. 1) The EAF covers an area of above 30,000 km 2 and may be the largest arid and semi-arid alluvial fan in the world based on the remote sensing survey. 2) Some surface parameters which are related to the paleoenvironmental change can be obtained from remote sensing data, such as the gravel size and potassium K parameters. 3) The forming process of the EAF and the corresponding environments will be understood deeply, combining the paleoenvironmental related parameters derived from remote sensing data and the geologic survey data

Influence of the micro- and nanoscale local mechanical properties of the interfacial transition zone on impact behavior of concrete made with different aggregates

International Nuclear Information System (INIS)

Erdem, Savaş; Dawson, Andrew Robert; Thom, Nicholas Howard

2012-01-01

The influence of the microscale local mechanical properties of the interfacial transition zone (ITZ) on macro-level mechanical response and impact behavior is studied for concretes made with copper slag and gravel aggregates. 3D nanotech vertical scanning interferometry, scanning electron microscopy coupled with energy dispersive X-ray micro-analysis, digital image analysis, and 3D X-ray computed tomography were used to characterize the microstructures and the ITZs. It was deduced that a stronger and denser ITZ in the copper slag specimen would reduce its vulnerability to stiffness loss and contribute to its elastic and more ductile response under impact loading. The analysis also indicated that a significant degeneration in the pore structure of the gravel specimen associated with a relatively weaker and non-homogeneous ITZ occurred under impact. Finally, it was also concluded that increased roughness of ITZ may contribute to the load-carrying capacity of concrete under impact by improving contact point interactions and energy dissipation.

Hazard assessment for a submarine landslide generated local-source tsunami from Kaikoura Canyon

Science.gov (United States)

DuBois, J.

2012-04-01

The Kaikoura Canyon, sediment sink for the Canterbury rivers north of Christchurch, comes to within 500 meters of shore at Goose Bay and accumulates approximately 1.5x106 m3 of sediment each year (Lewis and Barnes, 1999). This sediment, which has accumulated to about seventy meters in thickness (Walters et al., 2006), exhibits tensional fractures, is located in a tectonically active area and could result in catastrophic failure and potentially a local-source tsunami (Lewis and Banes, 1999; Lewis, 1998; Walters et al, 2006). Evidence suggests that this may have happened in the last two hundred years (Lewis, 1998; Lewis and Barnes 1999) and with a return period on the nearby Alpine and Hope faults also in the range of a one to two hundred years (Walters et al, 2006) could happen again relatively soon. A review of the historical record and oral traditions for Kaikoura shows that historically Kaikoura has been affected by 11 events of which 10 are from distant sources and one, though debatable, is possibly from a local source. There are some preserved traditions for the Kaikoura area. These taniwha stories from near Oaro and from the Lyell Creek have been repeated and changed though time though the general essence remains the same. These taniwha legends, though not conclusive, indicate a dangerous shoreline where people have been killed in the past, possibly by flooding or tsunami. Archaeological investigations at Kaikoura found evidence of a Maori occupational layers interrupted by water-worn stones, a "lens of clean gravel between occupation layers" and in other areas of the excavation, the gravels separate discontinuous periods of occupation (Fomison 1963; Foster, 2006). Additionally "pea-gravel" sized greywacke pebbles were found dispersed throughout sections of the South Bay shore platforms, though they were attributesd to slopewash (Duckmanton, 1974) this is less likely since the nearby hills are limestone. A geological investigation along the Kaikoura Coast, at

The spatial distribution of microfabric around gravel grains: indicator of till formation processes

Science.gov (United States)

KalväNs, Andis; Saks, Tomas

2010-05-01

Till micromorphology studies in thin sections is an established tool in the field of glacial geology. Often the thin sections are inspected only visually with help of mineralogical microscope. This can lead to subjective interpretation of observed structures. More objective method used in till micromorphology is measurement of apparent microfabric, usually seen as preferred orientation of elongated sand grains. In theses studies only small fraction of elongated sand grains often confined to small area of thin section usually are measured. We present a method for automated measurement of almost all elongated sand grains across the full area of the thin section. Apparently elongated sand grains are measured using simple image analysis tools, the data are processed in a way similar to regular till fabric data and visualised as a grid of rose diagrams. The method allows to draw statistical information about spatial variation of microfabric preferred orientation and fabric strength with resolution as fine as 1 mm. Late Weichselian tills from several sites in Western Latvia were studied and large variations in fabric strength and spatial distribution were observed in macroscopically similar till units. The observed types of microfabric spatial distributions include strong, monomodal and uniform distribution; weak and highly variable in small distances distribution; consistently bimodal distribution and domain-like pattern of preferred sand grain orientation. We suggest that the method can be readily used to identify the basic deformation and sedimentation processes active during the final stages of till formation. It is understood that the microfabric orientation will be significant affected by nearby large particles. The till is highly heterogonous sediment and the source of microfabric perturbations observed in thin section might lie outside the section plane. Therefore we suggest that microfabric distribution around visible sources of perturbation - gravel grains cut

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

Science.gov (United States)

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.

SEISMIC VELOCITY DETERMINATION IN GRAVEL AND SANDS USING PIEZOCRYSTALS

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Santamarina Juan Carlos

2008-06-01

Full Text Available The exact determination of seismic waves' propagation velocities has great importance in the geotechnics due to from that it is possible to determine, among other parameters, the dynamic ones: Elasticity E, Rigidity G, Poisson !, compressibility B; as well as to reach a knowledge on the stress-strain behavior for the studied soil samples. The seismic waves transmission considered in tests at laboratory scale carried out in the present work is a phenomenon that produces very small deformation, and so doesn't disturb the material. This allows
to apply the results in a more general scale to study the behavior of soils in situ and to predict their answer to stress.
With the purpose to study the response of particulate material subjected to seismic excitements at small scale, samples of gravels and sands were successively introduced in an odometric cell, exciting them with impulsive signals and registering the corresponding seismograms through general purpose piezoelectric transducers embedded in ends of the cell.
The distance source-receiver was interval increased, which enabled, from the corresponding regression straight lines, to calculate in precise form the propagation velocities (for P waves.
The tests were carried out in samples of dry alluvial soil with three different grain sizes. The respective frequency spectra of the signals were determined for two packing modes: loose and compact, what added information on the medium characteristics.

Areal distribution of 60Co, 137Cs, and 90Sr in streambed gravels of White Oak Creek Watershed, Oak Ridge, Tennessee

International Nuclear Information System (INIS)

Cerling, T.E.; Spalding, B.P.

1981-01-01

The concentrations of 90 Sr, 60 Co, and 137 Cs in streambed gravels from contaminated drainages in White Oak Creek Watershed were determined. Methods to determine the relative contributions of various sources to the total discharge from the watershed were developed. Principal sources of 90 Sr were: ORNL plant effluents (50%), leaching from solid waste disposal area (SWDA) 4 (30%), and leaching from SWDA 5 (10%). Minor sources included SWDA 3, the Molten Salt Reactor Facility, and intermediate-level liquid waste pit 1 with each representing 4% or less of the total basin discharge. The cooling water effluent from the High-Flux Isotope Reactor was the dominant source of 60 Co contamination in the watershed. ORNL plant effluents accounted for almost all the 137 Cs discharge from White Oak Creek basin. Downstream radionuclide concentrations were constant until significant dilution by other tributaries occurred. Any future activities giving rise to additional contamination can now be identified. Distribution coefficients between streambed gravels and streamwater for 85 Sr, 60 Co, and 137 Cs were 50, 560, and 8460 ml/g, respectively. An abridged radiochemical fractionation developed for 90 Sr was found to be as accurate and precise for these samples as the standard 90 Sr method above levels of 2 dpm/g

Engineered channel controls limiting spawning habitat rehabilitation success on regulated gravel-bed rivers

Science.gov (United States)

Brown, Rocko A.; Pasternack, Gregory B.

2008-05-01

In efforts to rehabilitate regulated rivers for ecological benefits, the flow regime has been one of the primary focal points of management strategies. However, channel engineering can impact channel geometry such that hydraulic and geomorphic responses to flow reregulation do not yield the sought for benefits. To illustrate and assess the impacts of structural channel controls and flow reregulation on channel processes and fish habitat quality in multiple life stages, a highly detailed digital elevation model was collected and analyzed for a river reach right below a dam using a suite of hydrologic, hydraulic, geomorphic, and ecological methods. Results showed that, despite flow reregulation to produce a scaled-down natural hydrograph, anthropogenic boundary controls have severely altered geomorphic processes associated with geomorphic self-sustainability and instream habitat availability in the case study. Given the similarity of this stream to many others, we concluded that the potential utility of natural flow regime reinstatement in regulated gravel-bed rivers is conditional on concomitant channel rehabilitation.

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

Science.gov (United States)

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.

PGDP Trichloroethene Biodegradation Investigation Summary Report: Regional Gravel Aquifer & Northwest Plume

Energy Technology Data Exchange (ETDEWEB)

Hampson, Steve [Univ. of Kentucky, Lexington, KY (United States). Kentucky Research Consortium for Energy and Environment

2008-09-01

The evaluation of biological degradation processes addressed by this report are part of a broad trichloroethene (TCE) Fate and Transport Investigation that includes four (4) topics of phased investigation (Table ES1) relative to degradation and/or attenuation of TCE in the Regional Gravel Aquifer (RGA) underlying the United States Department of Energy Paducah Gaseous Diffusion Plant (PGDP). In order of implementation the project phases are: (1) derivation of a TCE first-order rate constant by normalization of TCE values against technetium-99 (⁹⁹Tc) and chloride. 2) identification of the presence of microbes capable of aerobic co-metabolic TCE biodegradation using enzyme activity probes (this report); 3) Compound-specific isotope analysis (CSIA) to support prevalence of biotic and/or abiotic degradation processes; and 4) evaluation of potential abiotic RGA-TCE attenuation mechanisms including sorption. This report summarizes the Phase II activities related to the identification and evaluation of biological degradation processes that may be actively influencing TCE fate and transport in the RGA contaminant plumes at the United States Department of Energy (DOE) PGDP and its environs (Figure ES1). The goals of these activities were to identify active biological degradation mechanisms in the RGA through multiple lines of evidence and to provide DOE with recommendations for future TCE biological degradation investigations.

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

Energy Technology Data Exchange (ETDEWEB)

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.

Performance of a half-saturated vertical flow wetland packed with volcanic gravel in stormwater treatment.

Science.gov (United States)

Chen, Yaoping; Park, Kisoo; Niu, Siping; Kim, Youngchul

2014-01-01

A half-saturated pilot-scale wetland planted with Acorus calamus was built to treat urban stormwater. The design comprises a sedimentation tank for pretreatment, and a vertical flow volcanic gravel wetland bed equipped with a recirculation device. Eighteen rainfall events were monitored in 2012. The treatment system achieved total removal efficiencies of 99.4, 81, 50, and 86% for suspended solids, organic matter, nitrogen and phosphorus, respectively, and 29, 68, and 25% for copper, zinc, and lead, respectively, at a 3-day hydraulic residence time. In the wetland bed, the removal of ammonia, total nitrogen, and zinc were improved by recirculation. Plant uptake provided 18% of nitrogen removal and 39% of phosphorus removal. During the experimental stage, only 1.4% of the pore volume in substrate was reduced due to clogging, implying that the wetland can operate without clogging for a relatively long period.

River Discharge and Local Scale Habitat Influence LIFE Score Macroinvertebrate LIFE Scores

DEFF Research Database (Denmark)

Dunbar, Michael J.; Pedersen, Morten Lauge; Cadman, Dan

2010-01-01

Midlands of the U.K., we describe how local-scale habitat features (indexed through River Habitat Survey or Danish Habitat Quality Survey) and changing river flow (discharge) influence the response of a macroinvertebrate community index. The approach has broad applicability in developing regional flow...... Invertebrate index for Flow Evaluation (LIFE), an average of abundance-weighted flow groups which indicate the microhabitat preferences of each taxon for higher velocities and clean gravel/cobble substrata or slow/still velocities and finer substrata. 3. For the Danish fauna, the LIFE score responded to three...... of the channel (negative). In both cases, LIFE responded negatively to features associated with historical channel modification. We suggest that there are several mechanisms for these relationships, including the narrower tolerances of taxa preferring high velocity habitat; these taxa are also continually...

Late Cretaceous Sub-Marine Fan System in Batain Mélange Zone, the Fayah Formation in Northeastern Oman

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Iftikhar Ahmed Abbasi

2014-06-01

Full Text Available The Batain coast along the northeastern margin of Oman between Ra’s Al-Hadd and Ra’s Jibsch, is comprised of Permian to Late Cretaceous complex stratigraphy in a tectonically deformed area recording Permian rifting to late Cretaceous Tethys closure events. These rocks are thrust over Mesozoic and older autochthonous sedimentary cover in the form of a major nappe structure known as the Batain Nappe. The uppermost part of the Batain nappe is comprised of isolated outcrops of early Maastrichtian siliciclastic Fayah Formation dominated by gravity flow deposits. The Fayah Formation in the Jabal Fayah area is over four hundred meters thick and comprised of five distinct facies associations; namely, i coarsening-up sandstone, ii conglomerate, iii debris- flow, iv turbidite, and v inter-bedded sandstone and shale lithofacies. These lithofacies associations are repeated many times in the section. The sandstone lithofacies association exhibits a coarsening-upward trend making sequences tens of meters thick in various parts of the formation. Waterscape structures are common along with occasional sandstone dykes and convolute bedding, reflecting fluidized conditions of deposition. The conglomerate lithofacies association is comprised of a series of interbedded coarsening-upward pebble to gravel size conglomerates containing chert, limestone, granite and volcanic clasts ranging a few mm to cm in diameter. Occasionally these are interbedded with sandstone lithofacies. The conglomerate lithofacies was deposited by a high-energy channelized flow in a sub-aqueous setting. The debris-flow lithofacies association is a matrix supported chaotic mixture of clay and boulders of granite, limestone and volcanic rocks, some of which are meter-sized in diameter, and possibly derived from the nearby basement rocks such as the Jabal Ja’alan basement rocks. It constitutes the most dominant part of the formation. These sediments were deposited along a slope setting

Migration rates of volatile organic compounds in an unconsolidated sand and gravel aquifer system

International Nuclear Information System (INIS)

Naidu, J.R.; Paquette, D.E.; Porcelli, D.R.

1993-01-01

The movement of volatile organic compounds (VOCs) in an aquifer is dictated by its solubility, attenuation characteristics, recharge volume, and ground-water movement (velocity and direction). At Brookhaven National Laboratory, past handling and disposal practices at the Hazardous Waste Management Facility and current landfill have resulted in the release of VOCs and the radioisotope tritium to the underlying upper glacial aquifer which characterized by unconsolidated sands and gravel. The rate of VOC migration from these source areas was examined using the following parameters: (1) distribution of VOCs and tritium; (2) tritium/helium ratios, which provide an estimate of the age of the water, and hence the rate of ground-water movement; (3) ground-water flow velocities within the upper glacial aquifer utilizing conductivity, porosity, and gradient data. Preliminary results indicate that whereas the comparison of the calculated ground-water flow gradient to tritium/helium age determinations are fairly consistent, application to VOC movement is inconclusive, and will require additional monitoring which would also focus on the vertical component as well

Use of an oiled gravel column dosing system to characterize exposure and toxicity of fish to sunken heavy oil on spawning substrates

International Nuclear Information System (INIS)

Martin, J.; Hodson, P.

2010-01-01

In August 2005, a freight train derailment near the shore of Lake Wabamun near Edmonton, Alberta resulted in the release of nearly 150,000 litres of Bunker C oil on the lakeshore. The purpose of this study was to define the toxic load of oil in sediments to better describe the exposure and toxicity of fish to sunken heavy oil on spawning substrates. Heavy Bunker C fuel contains a complex mixture of polycyclic aromatic hydrocarbons (PAH), particularly the 3-4 ringed alkylated forms that cause sublethal toxic responses in early life stages of rainbow trout (Oncorhynchus mykiss). Oil patches still persist in near-shore sediments where fish spawn. This study evaluated how the behaviour of heavy oil in water interacts with exposure and toxicity to trout embryo. Flow-through oiled gravel columns were used to determine whether the toxic constituents of heavy oil are transferred to water quickly enough to cause toxicity. Embryonic trout exposed to the outflow of these columns showed signs of sublethal toxicity and dose-dependent mortality. In addition, column output of hydrocarbons and CYP1A induction in fish were flow-dependent. The desorption kinetics of the gravel column dosing was characterized in order to evaluate the toxicity of oil on these substrates and relate it back to toxicity of oil in sediments. The time to steady-state desorption of oil constituents in water was first determined, and then the rate at which different classes of oil constituents partition into water were identified.

Characteristics of Southern California coastal aquifer systems

Science.gov (United States)

Edwards, B.D.; Hanson, R.T.; Reichard, E.G.; Johnson, T.A.

2009-01-01

, litany of names for the various formations, lithofacies, and aquifer systems identified within these basins. Despite these nomenclatural problems, available data show that most basins contain similar sequences of deposits and share similar geologic histories dominated by glacio-eustatic sea-level fluctuations, and overprinted by syndepositional and postdepositional tectonic deformation. Impermeable, indurated mid-Tertiary units typically form the base of each siliciclastic groundwater basin. These units are overlain by stacked sequences of Pliocene to Holocene interbedded marine, paralic, fluvial, and alluvial sediment (weakly indurated, folded, and fractured) that commonly contain the historically named "80-foot sand," "200-foot sand," and "400-foot gravel" in the upper part of the section. An unconformity, cut during the latest Pleistocene lowstand (??18O stage 2; ca. 18 ka), forms a major sequence boundary that separates these units from the overlying Holocene fluvial sands and gravels. Unconfined aquifers occur in amalgamated coarse facies near the bounding mountains (forebay area). These units are inferred to become lithologically more complex toward the center of the basins and coast line, where interbedded permeable and low-permeability alluvial, fluvial, paralic, and marine facies contain confined aquifers (pressure area). Coastal bounding faults limit intrabasin and/or interbasin flow in parts of many basins. ?? 2009 Geological Society of America.

Surficial Geologic Map of the Evansville, Indiana, and Henderson, Kentucky, Area

Science.gov (United States)

Moore, David W.; Lundstrom, Scott C.; Counts, Ronald C.; Martin, Steven L.; Andrews, William M.; Newell, Wayne L.; Murphy, Michael L.; Thompson, Mark F.; Taylor, Emily M.; Kvale, Erik P.; Brandt, Theodore R.

2009-01-01

The geologic map of the Evansville, Indiana, and Henderson, Kentucky, area depicts and describes surficial deposits according to their origin and age. Unconsolidated alluvium and outwash fill the Ohio River bedrock valley and attain maximum thickness of 33-39 m under Diamond Island, Kentucky, and Griffith Slough, south of Newburgh, Indiana. The fill is chiefly unconsolidated, fine- to medium-grained, lithic quartz sand, interbedded with clay, clayey silt, silt, coarse sand, granules, and gravel. Generally, the valley fill fines upward from the buried bedrock surface: a lower part being gravelly sand to sandy gravel, a middle part mostly of sand, and a surficial veneer of silt and clay interspersed with sandy, natural levee deposits at river's edge. Beneath the unconsolidated fill are buried and discontinuous, lesser amounts of consolidated fill unconformably overlying the buried bedrock surface. Most of the glaciofluvial valley fill accumulated during the Wisconsin Episode (late Pleistocene). Other units depicted on the map include creek alluvium, slackwater lake (lacustrine) deposits, colluvium, dune sand, loess, and sparse bedrock outcrops. Creek alluvium underlies creek floodplains and consists of silt, clayey silt, and subordinate interbedded fine sand, granules, and pebbles. Lenses and beds of clay are present locally. Silty and clayey slackwater lake (lacustrine) deposits extensively underlie broad flats northeast of Evansville and around Henderson and are as thick as 28 m. Fossil wood collected from an auger hole in the lake and alluvial deposits of Little Creek, at depths of 10.6 m and 6.4 m, are dated 16,650+-50 and 11,120+-40 radiocarbon years, respectively. Fossil wood collected from lake sediment 16 m below the surface in lake sediment was dated 33,100+-590 radiocarbon years. Covering the hilly bedrock upland is loess (Qel), 3-7.5 m thick in Indiana and 9-15 m thick in Kentucky, deposited about 22,000-12,000 years before present. Most mapped surficial

The morphology and morphodynamics of sand-gravel subaquatic dunes: the Raba River estuary, Poland

Directory of Open Access Journals (Sweden)

Artur RADECKI-PAWLIK

2012-08-01

Full Text Available In the outlet of the Raba River to the Vistula, the biggest river in Poland, the morphology and morphodynamics of sand and fine-gravel subaquatic dunes were investigated. The site is situated in highland region just about the entrance to Polish Carpathians. The dunes formed on the Raba River bed estuary are composed of sand and fine gravel (d50 up to 11 mm. Systematic observation (within the 2000-2005 were made of geometry, sediment composition and hydraulic climate under which the dunes grew and decomposed. The investigation focuses here mostly on the geometrical parameters of these bed forms such as height, length, as well as granulometric characteristics of the sediment. Based on in-site measurements different hydraulic parameters were calculated such as shear stresses, resistant coefficient, Froude and Reynolds numbers and roughness coefficient. It was found that the relation between height (H and length (L of the Raba estuary dunes describes the formula: H = 0.05L0.35. Also these dunes are steeper and flatter then classical H/L index is: H/L = 0.0518L0.622. During the field campaign, when the foot access to the estuary was possible and dunes were spotted on the river bed the range of measured water velocity was from v = 0.39 m∙s-1 to v = 0.81 m∙s-1 with the highest velocity over the dune crest. At the same time the measured range of shear stresses within the dune field formation were from t = 0.115 N×m-2 to t = 1.59 N×m-2. On the field investigations the CCHE2D - two-dimensional unsteady flow and sediment transport model for non-equilibrium transport of non-uniform sediment mixtures – was applied. The model was used to simulate the morphodynamic changes along the outlet of the Raba River basing on field observations of the 2005 summer flood as well as calculate hydraulics parameters. It was also used to test and confirm the range of morphodynamic changes, which take place along the research reach where the dunes are being developed

Fly ashes as binders for the stabilisation of gravel. Laboratory tests and preparations for a field test; Flygaskor som bindemedel foer stabilisering av grusmaterial. Laboratorieundersoekningar samt foerberedelser infoer provbyggandet

Energy Technology Data Exchange (ETDEWEB)

Lahtinen, Pentti; Jyraevae, Harri; Maijala, Aino; Macsik, Josef

2005-04-01

The project is based on the results of a significant research project FACE (Fly Ash in Civil Engineering). The project aims at the development of binder recipes based on a chosen fly ash from Holmen Paper's Hallsta Pappersbruk for the renovation of a road. The development will benefit from the Finnish research and experience on this type of binders for geotechnical applications. The stabilisation should result in improving bearing capacity and better long-term durability and service life of the gravel roads. The environmentally friendly stabilisation system comprises also the possibility to reuse and recycle the material that already exists in the road to be renovated. The test materials for the development project were the gravel from a chosen test road and the fly ash of Holmen Paper AB. The fly ash was used as the binder material. The geotechnical tests included characterisation tests of the test materials, tests on the stabilised mixes and control tests for the stabilisation recipe. Also, there were tests for the assessment of the environmental impact of the stabilisation. Side by side with those tests there has been a full-scale test, a separate project in Hallstavik, to test the stabilisation process with respect to the technical, environmental and economical aspects of construction. The full-scale test will be reported separately. The project results imply that fly ash can be beneficially used as a binder for the stabilisation of gravel materials and similar materials. Fly ash can be used also with small amounts of other binder materials like cement or blast-furnace slag in order to have a frost resistant material. The project gives also basis for the development of binders for other types of applications, both for the renovation purposes and for the improvement of spoils for construction purposes.

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

Science.gov (United States)

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. Copyright © 2016 Elsevier B.V. All rights

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

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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

The anatomy of effective discharge: the dynamics of coarse sediment transport revealed using continuous bedload monitoring in a gravel-bed river during a very wet year

OpenAIRE

Downs, Peter W.; Soar, Philip J.; Taylor, Alex

2015-01-01

Indirect, passive approaches for monitoring coarse bedload transport could allow cheaper, safer, higher-resolution, longer-term data that revolutionises bedload understanding and informs river management. Here, insights provided by seismic impact plates in a downstream reach of a flashy gravel-bed river (River Avon, Devon, UK) are explored in the context of plate performance. Monitoring of a centrally-situated plate (IP1) during an extremely wet 12-month period demonstrated that impacts were ...

Performance of a forced convection solar drier integrated with gravel as heat storage material

Energy Technology Data Exchange (ETDEWEB)

Mohanraj, M. [Dr Mahalingam College of Engineering and Technology, Pollachi (India). Dept. of Mechanical Engineering; Chandrasekar, P. [Swinburne Univ. of Technology, Sarawak (Malaysia). School of Engineering Sciences

2009-07-01

Sun drying is the most common method used in India to dry agricultural products such as grains, fruits and vegetables. The rate of drying depends on solar radiation, ambient temperature, wind velocity, relative humidity, initial moisture content, type of crops, crop absorptivity and mass product per unit exposed area. However, this method of spreading the crop in a thin layer on the ground has several disadvantages. This paper reported on a study that focused on developing a forced convection solar drier integrated with heat storage materials for drying various agricultural crops. The indirect forced convection solar drier, integrated with gravel as a sensible heat material, was used to dry pineapple slices under conditions similar to those found in Pollachi, India. The performance of the system was discussed along with the drying characteristics, drying rate, and specific moisture extraction rate. The results showed that the moisture content (wet basis) of pineapple was reduced from about 87.5 to 14.5 per cent (equilibrium moisture content) in about 29 hours in the bottom tray and 32 hours in the top tray. The thermal efficiency of the solar air heater was also reviewed. 9 refs., 5 figs.

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

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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. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

The Geophysical Investigation of Drinkable Water at Shkodra Region

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Jata, I. B.; Kavaja, V. S.; Kotori, A. N.

2002-12-01

The drinkable water has been and is a great problem for the population of Shkodra region, NW of Albania. Many studies have been widely used in this domain by Geophysical Center of Tirana.Two case histories are presented in this paper.One, the Drini river terraces and other example near coast line.Actually, the need from fresh water are increasing due to the high demand for water supply. In compliance with geographical and geological classification the survey is in a narrow sense belongs to marginal part of the Nenshkodra plain. Geological situation of survey area consists on diverse geological make up.The stratigrafic section begins with carbonate formations (Cr2) have a monoclyne structure, nearly NW-SE trending. Paleogene formations is composed mainly: by carbonatic flysch (Pg2), alevrolitic-sanstone formation(Pg31 - Pg32) and Oligocene deposits with alevrolitic-clay-sandston formation (Pg13). Quaternary formation interbeded by silt, clay, sand and gravel layers. In survey area the thickness of concerned younger deposits does not surpass 50-70m, therefor we were able to draw up a picture of the thickness and depositional conditions of the Quaternary accumulations as corresponding in precision to given scale. The aim of the study is been delineation of aquifers and aquicludes soils extension within terrace profile based in the resistivity parameter as well as zone of aeration and water table. In the paper are described all the phases from field measurements, data processing and interpretation, as well as the soil thickness and resistivity maps, the thickness and resistivity maps of gravel terraces was build up. The high resistivity values show best aquifers gravel deposits. But when the gravel terrace companies with large thickness of the layers it is practical to multiply these two parameters, Hi x *i = S. In the other hand, one and more important maps are the correlation of rocks permeability T (sq.m/day) with transversal resistivity (S) parameters. In preparing

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

Science.gov (United States)

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

Application of GPR Method for Detection of Loose Zones in Flood Levee

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Gołębiowski, Tomisław; Małysa, Tomasz

2018-02-01

In the paper the results of non-invasive georadar (GPR) surveys carried out for detection of loose zones located in the flood levee was presented. Terrain measurements were performed on the Vistula river flood levee in the village of Wawrzeńczyce near Cracow. In the investigation site, during the flood in 2010, leakages of levee were observed, so detection of inner water filtration paths was an important matter taking into account the stability of the levee during the next flood. GPR surveys had reconnaissance character, so they were carried out with the use of short-offset reflection profiling (SORP) technique and radargrams were subjected to standard signal processing. The results of surveys allowed to outline main loose zone in the levee which were the reason of leakages in 2010. Additionally gravel interbeddings in sand were detected which had an important influence, due to higher porosity of such zones, to water filtration inside of the levee. In the paper three solutions which allow to increase quality and resolution of radargrams were presented, i.e. changeable-polarisation surveys, advanced signal processing and DHA procedure.

Measuring gravel transport and dispersion in a mountain river using passive radio tracers

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Bradley, D. N.; Tucker, G. E.

2012-01-01

Random walk models of fluvial sediment transport recognize that grains move intermittently, with short duration steps separated by rests that are comparatively long. These models are built upon the probability distributions of the step length and the resting time. Motivated by these models, tracer experiments have attempted to measure directly the steps and rests of sediment grains in natural streams. This paper describes results from a large tracer experiment designed to test stochastic transport models. We used passive integrated transponder (PIT) tags to label 893 coarse gravel clasts and placed them in Halfmoon Creek, a small alpine stream near Leadville, Colorado, USA. The PIT tags allow us to locate and identify tracers without picking them up or digging them out of the streambed. They also enable us to find a very high percentage of our rocks, 98% after three years and 96% after the fourth year. We use the annual tracer displacement to test two stochastic transport models, the Einstein–Hubbell–Sayre (EHS) model and the Yang–Sayre gamma-exponential model (GEM). We find that the GEM is a better fit to the observations, particularly for slower moving tracers and suggest that the strength of the GEM is that the gamma distribution of step lengths approximates a compound Poisson distribution. Published in 2012. This article is a US Government work and is in the public domain in the USA.

Low-cost multi-stage filtration enhanced by coagulation-flocculation in upflow gravel filtration

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L. D. Sánchez

2012-12-01

Full Text Available This paper assesses the operational and design aspects of coagulation and flocculation in upflow gravel filters (CF-UGF in a multi-stage filtration (MSF plant. This study shows that CF-UGF units improve the performance of MSF considerably, when the system operates with turbidity above 30 NTU. It strongly reduces the load of particulate material before the water enters in the slow sand filters (SSF and therewith avoids short filter runs and prevents early interruption in SSF operations. The removal efficiency of turbidity in the CF-UGF with coagulant was between 85 and 96%, whereas the average efficiency without coagulant dosing was 46% (range: 21–76%. Operating with coagulant also improves the removal efficiency for total coliforms, E-coli and HPC. No reduction was observed in the microbial activity of the SSF, no obstruction of the SSF bed was demonstrated and SSF runs were maintained between 50 and 70 days for a maximum head loss of 0.70 m. The most important advantage is the flexibility of the system to operate with and without coagulant according to the influent turbidity. It was only necessary for 20% of the time to operate with the coagulant. The CF-UGF unit represented 7% of total construction costs and the O&M cost for the use of coagulant represented only 0.3%.

The impact of structural development on near bed flow dynamics in gravel bed rivers: coupling flume experiments with numerical modelling

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Ockelford, A.; Hardy, R. J.; Rice, S. P.; Powell, M.

2017-12-01

It is increasingly being recognised that gravel bed rivers develop a surface `texture' in response to changes in the flow and sediment regime. This textural response often takes the form of a bed structure which develops to ultimately stabilise the surface across a range of spatio-temporal scales and it is these topographical structures which determine the flow structures that develop over the river bed. However, our ability to measure and parameterise that structure in ways that are useful and meaningful for the prediction of flow dynamics, still remains inadequate; this paper uses a three dimensional numerical model to assess how the temporal development of structure influences the near bed flow dynamics. Using a suite of flume based experiments a unimodal grain size distribution (σg = 1.30, D50 = 8.8mm) was exposed to three different levels of constant bed shear that produced sediment transport conditions ranging from marginal transport to conditions approaching full mobility of all size fractions. Surface structuring characteristics were measured at a high spatio-temporal resolution such that the time evolution of the beds could be fully described. In total 54 surfaces were generated and run through a Reynolds averaged three dimensional numerical model with an Rng turbulence closure. The topography input included using an immersed boundary technique within a Cartesian framework. Discussion concentrates on the how the trajectory of structural evolution under the different treatments affects the near bed flow dynamics. Specifically links are made between how the scales of boundary topography influence the flow and discusses how the measured flow variability at any one point will contain both locally derived and upstream-inherited flow structures, according to the range of scales of bed topography present. Keywords: Graded, Sediment, Structure, Turbulence, Modelling

Measurement of the bed material of gravel-bed rivers

Science.gov (United States)

Milhous, R.T.; ,

2002-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

Science.gov (United States)

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.

More than ten million years of hyper-aridity recorded in the Atacama Gravels

Science.gov (United States)

Sun, Tao; Bao, Huiming; Reich, Martin; Hemming, Sidney R.

2018-04-01

The Atacama Desert's hyper-aridity is closely linked to the development of world-class copper and nitrate/iodine ores and to regional tectonics and global paleoclimate changes in the Cenozoic era. The timing when the hyper-aridity commenced remains controversial, with proposed ages ranging from Late Oligocene to Pleistocene. In this study, we provide an independent constraint on the initiation of Atacama hyper-aridity utilizing a 100-m deep profile within the Atacama Gravels and underneath porphyry copper deposit in Spence, northern Chile. The overall high concentration of sulfate (up to 10 wt%) and a multimodal distribution of water soluble salt (sulfates, chlorides and nitrates) indicate multiple generations of sedimentation and salt accumulation events under semi-arid to hyper-arid climate conditions. The multiple sulfate isotope compositions (Δ17O, δ18O, δ34S) of the upper section (-15.0 to -34.5 m) are close to those of modern hyperarid surface sulfates, while the lower section (-34.5 to -65 m) displays a depth dependent isotope trend that is best interpreted as marking a period of climate change from semi-arid to hyper-arid. When these data are combined with new chronological 40Ar/39Ar dates obtained from a volcanic ash layer at depth of -28.0 m, our results show that hyper-arid condition in the Atacama Desert was prevailing at least prior to 9.47 Ma and may go back as old as the middle Miocene.

Stratigraphy, geochronology, and paleoenvironments of Miocene - Pliocene boundary of San Fernando, Belén (Catamarca, northwest of Argentina)

Science.gov (United States)

Bonini, Ricardo A.; Georgieff, Sergio M.; Candela, Adriana M.

2017-11-01

The Santa María-Hualfín Basin was proposed as a regional synchronous lithostratigraphic depocenter in the geological province of Northwestern Pampean Ranges, Northwestern Argentina. However, new 40Ar-39Ar dating indicates that deposits toward the east, in Santa María Valley (Santa María Department), are younger than the western depocenter in San Fernando (Belén Department). Therefore, it would be more appropriate to study these valleys as separate basins, each one with its own tecto-sedimentary features. The east basin, named in this paper Villavil-Quillay, constitutes an elongated independent basin that developed along the front of the eastern Puna bordering with Papachacra and Durazno Ranges. This basin is composed of more than 3000 m of mudstone, sandstone, conglomerates, volcaniclastic and pyroclastic deposits. Villavil-Quillay basin develops onto a peneplain of Precambrian and lower Cambrian rocks, most of which are metamorphic and granites rocks. The sedimentary fill consists of Cretaceous? and Cenozoic continental deposits. The Cenozoic record is composed of a) the Santa María Group (Miocene-Pliocene), formed by Las Arcas, Chiquimil, Andalhuala and Corral Quemado Formations, and b) the Punaschotter unit (Puna's Gravels in German, Pleistocene). This study involves the Andalhuala, Corral Quemado and Punaschotter deposits cropping out in San Fernando area. The set of identified facies assemblage corresponding to the Andalhuala Formation shows a vertical variation of fluvial sub-environments, varying from permanent sandy braided rivers to gravel rivers and aeolian dunes culminating in an alluvial dry cycle. While facies assemblages of the Corral Quemado Formation allow inferring the development of ephemeral water bodies from secondary channels on the floodplain, the Punaschotter conglomerates indicate the development of gravel channels and bars. Three samples of tuffs interbedded in the sedimentary levels of Andalhuala Formation were dated indicating that

Orbital radar studies of paleodrainages in the central Namib Desert

Science.gov (United States)

Lancaster, N.; Schaber, G.G.; Teller, J.T.

2000-01-01

Orbital radar images of the central Namib Desert show clearly the extent of relict fluvial deposits associated with former courses of the Tsondab and Kuiseb rivers. South of the Kuiseb River, radar data show the existence of a drainage network developed in calcrete-cemented late Tertiary fluvial deposits. The sand-filled paleovalleys are imaged as radar-dark tones in contrast to the radar-bright interfluves where the calcreted gravels occur. The drainage network developed as a result of local runoff from indurated gravels and channeled surface and subsurface flow to the sites of the many interdune lacustrine deposits found in the area. (C) Elsevier Science Inc., 2000.Orbital radar images of the central Namib Desert show clearly the extent of relict fluvial deposits associated with former courses of the Tsondab and Kuiseb rivers. South of the Kuiseb River, radar data show the existence of a drainage network developed in calcrete-cemented late Tertiary fluvial deposits. The sand-filled paleovalleys are imaged as radar-dark tones in contrast to the radar-bright interfluves where the calcreted gravels occur. The drainage network developed as a result of local runoff from indurated gravels and channeled surface and subsurface flow to the sites of the many interdune lacustrine deposits found in the area.

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

Science.gov (United States)

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 ϕ, 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 ϕ, 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 α 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 α, which incorporates porosity data, with K produces only a slightly better correlation and further emphasizes the weak influence of the bulk value of ϕ on K.

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

Science.gov (United States)

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.

A new CT scan methodology to characterize a small aggregation gravel clast contained in a soft sediment matrix

Science.gov (United States)

Fouinat, Laurent; Sabatier, Pierre; Poulenard, Jérôme; Reyss, Jean-Louis; Montet, Xavier; Arnaud, Fabien

2017-03-01

Over the past decades, X-ray computed tomography (CT) has been increasingly applied in the geosciences community. CT scanning is a rapid, non-destructive method allowing the assessment of relative density of clasts in natural archives samples. This study focuses on the use of this method to explore instantaneous deposits as major contributors to sedimentation of high-elevation lakes in the Alps, such as the Lake Lauvitel system (western French Alps). This lake is located within a very steep valley prone to episodic flooding and features gullies ending in the lake. This variety of erosion processes leads to deposition of sedimentary layers with distinct clastic properties. We identified 18 turbidites and 15 layers of poorly sorted fine sediment associated with the presence of gravels since AD 1880. These deposits are respectively interpreted as being induced by flood and wet avalanche. This constitutes a valuable record from a region where few historical records exist. This CT scan approach is suitable for instantaneous deposit identification to reconstruct past evolution and may be applicable to a wider variety of sedimentary archives alongside existing approaches.

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

Energy Technology Data Exchange (ETDEWEB)

Schaider, Laurel A., E-mail: schaider@silentspring.org; 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 1 mg/L NO{sub 3}-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. - Highlights: • We tested 20 domestic drinking water wells for 117 organic wastewater compounds. • PFASs, pharmaceuticals, and an artificial sweetener were most frequently detected. • Nitrate, boron, and well depth were all correlated with PFASs and pharmaceuticals. • Acesulfame

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

International Nuclear Information System (INIS)

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

2016-01-01

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 1 mg/L NO_3-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. - Highlights: • We tested 20 domestic drinking water wells for 117 organic wastewater compounds. • PFASs, pharmaceuticals, and an artificial sweetener were most frequently detected. • Nitrate, boron, and well depth were all correlated with PFASs and pharmaceuticals. • Acesulfame (artificial

Final Scientific/Technical Report - DE-FG02-06ER64172 - Reaction-Based Reactive Transport Modeling of Iron Reduction and Uranium Immobilization at Area 2 of the NABIR Field Research Center - Subproject to Co-PI Eric E. Roden

International Nuclear Information System (INIS)

Roden, Eric E.

2009-01-01

This report summarizes research conducted in conjunction with a project entitled 'Reaction-Based Reactive Transport Modeling of Iron Reduction and Uranium Immobilization at Area 2 of the NABIR Field Research Center', which was funded through the Integrative Studies Element of the former NABIR Program (now the Environmental Remediation Sciences Program) within the Office of Biological and Environmental Research. Dr. William Burgos (The Pennsylvania State University) was the overall PI/PD for the project, which included Brian Dempsey (Penn State), Gour-Tsyh (George) Yeh (Central Florida University), and Eric Roden (formerly at The University of Alabama, now at the University of Wisconsin) as separately-funded co-PIs. The project focused on development of a mechanistic understanding and quantitative models of coupled Fe(III)/U(VI) reduction in FRC Area 2 sediments. The work builds on our previous studies of microbial Fe(III) and U(VI) reduction, and was directly aligned with the Scheibe et al. ORNL FRC Field Project at Area 2. Area 2 is a shallow pathway for migration of contaminated groundwater to seeps in the upper reach of Bear Creek at ORNL, mainly through a ca. 1 m thick layer of gravel located 4-5 m below the ground surface. The gravel layer is sandwiched between an overlying layer of disturbed fill material, and 2-3 m of undisturbed shale saprolite derived from the underlying Nolichucky Shale bedrock. The fill was put in place when contaminated soils were excavated and replaced by native saprolite from an uncontaminated area within Bear Creek Valley; the gravel layer was presumably installed prior to addition of the fill in order to provide a stable surface for the operation of heavy machinery. The undisturbed saprolite is highly weathered bedrock that has unconsolidated character but retains much of the bedding and fracture structure of the parent rock (shale with interbedded limestone). Hydrological tracer studies conducted during the Scheibe et al. field

深厚砂砾石地层固结灌浆在实际工程中的应用%Consolidation Grouting of Deep Sand-gravel Stratum in Practical Engineering Application

Institute of Scientific and Technical Information of China (English)

赵健飞

2014-01-01

水利工程施工过程中，经常会遇到水工建筑物直接修建在砂砾石地层上，为了提高砂砾石地层的整体性、密实性并降低其透水率，一般需要对坝基采取全面的固结灌浆，必要时也在坝基上、下游一定范围内进行固结灌浆。结合水利枢纽的工程实践，对泄洪冲沙闸底板进行全面的固结灌浆处理，施工过程中采用自上而下分段灌浆方法，对现有的钻探与灌浆工艺技术进行优化组合，最终经灌后质量检查，结果满足深厚砂砾石覆盖层固结灌浆的设计要求，取得了良好的效果。%In the construction of hydraulic engineering projects ,the hydraulic structures are often directly built on the sand gravel stratum .In order to improve the integrity of sandy gravel stratum and reduce its permeability ,it is common to apply comprehensive consolidation grouting on the dam foundation ,sometimes consolidation grouting is also carried out in a certain range of the upstream and downstream of the dam foundation when necessary .In the construction of an engineer-ing project ,the comprehensive consolidation grouting was applied on the floor of the outlet sluice with descending stage grouting method during the construction process .This method combined the advantages of the existing drilling and grout-ing techniques and reached a optimum combination .The result of the quality inspection indicates that the outcome not on-ly meets the specifications of consolidation grouting of deep sand gravel stratum ,but also has excellent performance .

Three Sisters Dam: Investigations and monitoring

International Nuclear Information System (INIS)

Slopek, R.J.; Courage, L.J.R.; Keys, R.A.

1990-01-01

The geotechnical investigations, monitoring and interpretation of data associated with the evaluation of the Three Sisters Dam, which has been suffering from excessive seepage and is in need of enhancement, are outlined. The Three Sisters Dam is located in the continental ranges of the Rocky Mountains in Alberta, impounding the Spray Reservoir, and is founded on 60 m of interbedded sand, gravel, silt and clay layers. The computer code PC-SEEP was used to evaluate seepage. Details are provided of drilling, ground-penetrating radar surveys, seismic surveys, penstock inspection, sinkhole activity, piezometer monitoring, silt wells, settlement monuments, and tailrace monitoring. The intensive investigations of the foundations showed that they consist of a complex formation of interfingered stratified layers and leases of talus and glaciofluvial deposits. Due to the depth and nature of these materials drill hole penetration was limited to the use of the Becker hammer. This equipment successfully delineated the major soil horizons of the foundation. The continued information attained from inspection, drilling, testing, radar surveys, seismic work, monitoring of piezometers, leakage, silt wells and settlement monuments indicated that there are no large voids within the foundation of the dam. 2 refs., 12 figs

The microfauna assemblages as indicators of paleoenvironmental changes in the Miocene fluvial- lacustrine cycles (NE Duero Basin, Spain

Directory of Open Access Journals (Sweden)

A. Herrero-Hernández

2016-11-01

Full Text Available The siliclastic and carbonate deposits are interbedded in the Villadiego area (Miocene, NE Duero Basin. They have been subdivided into two high-rank depositional sequences: DDS and CDS. The sedimentary analysis of these units and the study of the microfauna content, mainly ostracods, led to the identification of lacustrine-fluvial interaction systems. The sedimentary characteristics reveal the existence of fluvial systems of gravel, flood plains and lacustrine systems that were interconnected and intimately related in north-south direction. In the sedimentological analysis, thirteen types of fluvial and lacustrine lithofacies and six genetic facies associations were recognized. The top of DDS is the result of lake level risings. The CDS shows a deepening-shallowing cycle. The ostracod micropaleontological analysis of the sediments have been studied, with the aim of reconstructing the palaeoenvironmental evolution of this area. These microfauna assemblages integrated with the analysis of the sedimentary facies allowed to conclude the existence of lakes with a water-bearing level of few tens of meters. A change in the chemical conditions of the waters, which evolved from oligohaline and carbonated to mesohaline and sulphated is concluded.

Stratigraphy and depositional environments of the upper Pleistocene Chemehuevi Formation along the lower Colorado River

Science.gov (United States)

Malmon, Daniel V.; Howard, Keith A.; House, P. Kyle; Lundstrom, Scott C.; Pearthree, Philip A.; Sarna-Wojcicki, Andrei M.; Wan, Elmira; Wahl, David B.

2011-01-01

about 111±2 and 57±2 ka and was most active in the later part of this time interval, during Marine Oxygen Isotope (MOI) stage 4 (between 74 and 59 ka ago). Chemically similar tephra in cores from Owens Lake and Walker Lake are approximately 70 and 74 ky old, based on age models of those cores. Other lines of stratigraphic evidence from nine tephra-containing sections in the Basin and Range are also consistent with an age assignment for the Monkey Rock tephra of ~72 ky, near the beginning of MOI stage 4. We propose to designate the Chemehuevi Formation as a formal lithostratigraphic unit, and propose as the type section a well exposed outcrop near the ranger station at Katherine Landing, Arizona, in the Lake Mead National Recreation Area. This exposure shows the two dominant facies, an example of one of the four known tephra layers, and interbedded lenses of locally derived gravel. In the type section, as in many of the other examples of the formation, the sand facies overlies the mud facies on a conspicuous, abrupt erosional surface; however, nearby is a contiguous section demonstrating that the mud and sand facies interfinger. In addition to the type section, measured reference sections compiled here illustrate other important lithologic and stratigraphic features of the formation. Our preferred interpretation of the Chemehuevi Formation is that it contains the remnants of deposits formed during a single major episode of fluvial aggradation, during which the Colorado River filled its valley with a great volume of dominantly sand-size sediment. This would reflect an increase in the supply of sand-size sediment, and(or) a reduction in transport capacity below the mouth of Grand Canyon. The most likely cause for the aggradation is an extraordinary increase in sand supply, likely due to widespread climatic change. However, other explanations have not been ruled out. Other aggradation events predated the Chemehuevi Formation, and some smaller events may have postdated the

Geohydrology and water quality of the stratified-drift aquifers in Upper Buttermilk Creek and Danby Creek Valleys, Town of Danby, Tompkins County, New York

Science.gov (United States)

Miller, Todd S.

2015-11-20

In 2006, the U.S. Geological Survey, in cooperation with the Town of Danby and the Tompkins County Planning Department, began a study of the stratified-drift aquifers in the upper Buttermilk Creek and Danby Creek valleys in the Town of Danby, Tompkins County, New York. In the northern part of the north-draining upper Buttermilk Creek valley, there is only one sand and gravel aquifer, a confined basal unit that overlies bedrock. In the southern part of upper Buttermilk Creek valley, there are as many as four sand and gravel aquifers, two are unconfined and two are confined. In the south-draining Danby Creek valley, there is an unconfined aquifer consisting of outwash and kame sand and gravel (deposited by glacial meltwaters during the late Pleistocene Epoch) and alluvial silt, sand, and gravel (deposited by streams during the Holocene Epoch). In addition, throughout the study area, there are several small local unconfined aquifers where large tributaries deposited alluvial fans in the valley.

Geohydrology of the valley-fill aquifer in the Corning area, Steuben County, New York

Science.gov (United States)

Miller, Todd S.; Belli, J.L.; Allen, R.V.

1982-01-01

This report is the seventh in a series of 11 map sets depicting geohydrologic conditions in selected aquifers in upstate New York. Geohydrologic data are compiled on six maps at 1:24,000 scale. Together, the maps provide a comprehensive overview of a major valley-fill aquifer in southeastern Steuben County. The maps include surficial geology, geologic sections, water-infiltration potential of soil zone, aquifer thickness, potentiometric-surface elevations, and land use. The valley-fill deposits consist of alluvial silt, sand, and gravel, glacial-outwash (sand and gravel), till, and lacustrine silt and clay. The sand and gravel beds have relatively high permeabilities, whereas the till and silt deposits have relatively low permeabilities. Water-table conditions prevail in unconfined sand and gravel along the valley margin. Artesian conditions are found locally in sand and gravel confined under silt and clay in the middle of the valley. Recharge occurs nearly everywhere on the valley floor, but principally along the margin of the valley, where highly permeable land surface conditions exist, and runoff from the hillsides is concentrated. The use of land overlying the aquifer is a mixture of residential, commercial, agricultural, and industrial uses. (USGS)

comparison of authigenic minerals in sandstones and interbedded

African Journals Online (AJOL)

a

Mechanically compacted mudstones, siltstones and shales expelled large ... quartz, and (16) hydrocarbon migration; pyrite and apatite precipitation [1, 7, 12]. ... relationship of the authigenic minerals, burial history and fluid inclusions studies.

Isotopic identification and quantification of seawater influx into a groundwater body using environmental isotopes (2H,18O)

International Nuclear Information System (INIS)

Stichler, W.; Weise, S.M.; Trimborn, P.

2001-01-01

The development of optimal strategies for groundwater protection and for minimising the danger to groundwater through raw material excavation presupposes a well-founded hydrogeological knowledge of the complex interactions between flooded gravel pit and groundwater. The present study was dedicated to a quantitative determination of the groundwater throughput of a representative flooded gravel pit, the Alte Vogelbaggersee, on the basis of isotope experiments. Water samples were taken from groundwater analysis points upstream and downstream of the gravel pit and in the pit itself over a two-year observation period. In addition to isotope analysis ( 2 H, 1 8O) the scope of measurements included local parameters and chemical analysis in vertical profiles, time series and spatial distributions on selected days [de

Use of local discarded materials in concrete

OpenAIRE

Taha, Ramzi; Al-Nuaimi, Nasser; Kilayli, Abdulazeez; Salem, Abdelhamid Ben

2014-01-01

Steel slag, a by-product of steel manufacturing, is generated in large quantities in Qatar. In fact, it is estimated that more than 400,000tons of steel slag are generated annually in the country. Gravel, resulting from washing sand, is also produced at more than 500,000tons/year in Qatar. Both materials are not efficiently used in the country and most of its aggregate (gabbro) needs are imported from neighboring countries. This paper presents the results obtained on the use of steel slag, gr...

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

Energy Technology Data Exchange (ETDEWEB)

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

Stabilization techniques for reactive aggregate in soil-cement base course.

Science.gov (United States)

2003-01-01

Anhydrite (CaSO4) beds occur as a cap rock on a salt dome in Winn Parish in north Louisiana. Locally known as Winn Rock, it has been quarried for gravel for road building. It has been used as a surface course for local parish and logging roads. Stabi...

How small bugs tie down big rocks: Measuring and modeling the forces acting between nets spun by Caddisfly larvae (Hydropsychidae) and gravel particles at the onset of motion

Science.gov (United States)

Mclaughlin, M. K.; Tumolo, B.; Sklar, L. S.; Albertson, L.; Daniels, M.

2017-12-01

The influence of life on geomorphic processes is commonly inferred from correlations between the size and abundance of individual organisms and the change in process thresholds and rates from abiotic conditions. However, to understand and model the underlying mechanisms, it is helpful to make direct measurements of the forces acting between organisms and the earth materials they inhabit. For example, flume studies have found that the presence of net-spinning caddisfly larvae (Trichoptera: Hydropsychidae) can increase the shear stress required to initiate particle motion by more than a factor of two, with potentially significant implications for the timing and magnitude of bedload sediment transport in gravel-bedded rivers. To explore the underlying mechanics we conducted flume experiments at the Stroud Water Research center in Avonadale, Pennsylvania, using strain gages to measure the forces acting between caddisfly nets and sediment particles of various sizes, during the process of initial particle motion. We combine these measurements with high-speed video images to document for the first time, the three dimensional dynamics of net stretching, tearing, and detachment that govern the magnitude of the increase in critical shear stress. We are using these data and insights to substantially improve a previously published theoretical model for the mechanics of sediment stabilization by caddisfly larvae. In particular, we seek to constrain the range of particle sizes potentially stabilized by caddisfly larvae and explain mechanistically why the effect of caddisfly nets varies with particle size. These predictions have implications for understanding feedbacks between bed stabilization by caddisflies, insect density, inter-specific niche partitioning, and the movement of sediment that shapes gravel-bed channels.

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

Science.gov (United States)

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.

Deformation of ``Villafranchian'' lacustrine sediments in the Chisone Valley (Western Alps, Italy)

Science.gov (United States)

Collo, Giovanni; Giardino, Marco

1997-09-01

The Chisone Valley is located in the internal NW Alps, in the Pinerolese District, an area characterized by present low to medium seismicity. Fine-grained sediments (sand, silt and clay with interbedded gravel) crop out in the lower Chisone Valley: they were first interpreted as glaciolacustrine deposits, and then as a lacustrine infilling of the valley floor probably due to differential uplifting of the valley mouth. Review of this data, together with new field and palynological observations, lead us to refer the lacustrine deposits to approximately the Lower Pleistocene (Villafranchian). In many outcrops, the lacustrine deposits show strong soft-sediment deformation such as convolute laminations, water-escape structures and disrupted beds, some of them associated with folds and faults (cm to dm in size); only two sites show metric to decametric folds and faults trending E-W and N-S. Detailed structural analysis conducted along a recently exposed section (Rio Gran Dubbione site) shows several soft-sediment deformation features on the limbs of mesoscale folds. Because of their intimate structural association, the origin of these minor structures seems to be connected to synsedimentary activity on reverse and normal faults (m to dm in size) affecting the lacustrine deposits in the same locality. Soft-sediment deformation features can be interpreted as possible paleoseismites. If so, the present seismicity of the Pinerolese District, which is the major area of such activity in NW Italy, cannot be considered an isolated episode in the geological evolution of the region; even if there is no supporting evidence for continuous seismicity, the deformations in the lacustrine sediments of the Chisone Valley testify to Early Pleistocene seismic activity, probably related to the recent tectonic evolution of the internal side of the NW Alps.

Numerical simulation of the free surface and water inflow of a slope, considering the nonlinear flow properties of gravel layers: a case study

Science.gov (United States)

Yang, Bin; Yang, Tianhong; Xu, Zenghe; Liu, Honglei; Shi, Wenhao; Yang, Xin

2018-02-01

Groundwater is an important factor of slope stability, and 90% of slope failures are related to the influence of groundwater. In the past, free surface calculations and the prediction of water inflow were based on Darcy's law. However, Darcy's law for steady fluid flow is a special case of non-Darcy flow, and many types of non-Darcy flows occur in practical engineering applications. In this paper, based on the experimental results of laboratory water seepage tests, the seepage state of each soil layer in the open-pit slope of the Yanshan Iron Mine, China, were determined, and the seepage parameters were obtained. The seepage behaviour in the silt layer, fine sand layer, silty clay layer and gravelly clay layer followed the traditional Darcy law, while the gravel layers showed clear nonlinear characteristics. The permeability increases exponentially and the non-Darcy coefficient decreases exponentially with an increase in porosity, and the relation among the permeability, the porosity and the non-Darcy coefficient is investigated. A coupled mathematical model is established for two flow fields, on the basis of Darcy flow in the low-permeability layers and Forchheimer flow in the high-permeability layers. In addition, the effect of the seepage in the slope on the transition from Darcy flow to Forchheimer flow was considered. Then, a numerical simulation was conducted by using finite-element software (FELAC 2.2). The results indicate that the free surface calculated by the Darcy-Forchheimer model is in good agreement with the in situ measurements; however, there is an evident deviation of the simulation results from the measured data when the Darcy model is used. Through a parameter sensitivity analysis of the gravel layers, it can be found that the height of the overflow point and the water inflow calculated by the Darcy-Forchheimer model are consistently less than those of the Darcy model, and the discrepancy between these two models increases as the permeability

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

Science.gov (United States)

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

Nature and composition of interbedded marine basaltic pumice in ...

Indian Academy of Sciences (India)

(core) of several samples were obtained by drilling, along with ... Ba, V, Ni, Zn) for five pumice samples were deter- mined by XRF ..... may also take place in the shallow water environ- ..... In: Soils and Sediments (eds) Paquet H and Clauer N,.

Hydrogeology and water quality of sand and gravel aquifers in McHenry County, Illinois, 2009-14, and comparison to conditions in 1979

Science.gov (United States)

Gahala, Amy M.

2017-10-26

, pesticides, and volatile organic compounds. The results were compared to health‑based and aesthetically based standards, which include the U.S. Environmental Protection Agency Maximum Contaminant Level (EPA MCL), and EPA Secondary Maximum Contaminant Levels (SMCL), as well as EPA Health-based Standards Drinking Water Advisories. Health‑based standards were exceeded for arsenic in 22 percent, sodium in 20 percent, and nitrates in 2 percent of the monitoring wells sampled. Aesthetically based standards were exceeded for total dissolved solids in 33 percent, chloride in 11 percent, iron in 85 percent, and manganese in 30 percent of the wells sampled. Many of these same constituents, such as arsenic, iron, and manganese, are naturally occurring but become elevated in areas that have anoxic, mixed, and suboxic conditions. Some areas of potential vulnerability to anthropogenic-sourced constituents in the sand and gravel aquifers were evidenced by trace amounts of volatile organic compounds and pesticides detected in water-quality samples from shallow wells (total depth less of than 46 feet below land surface) near urban settings, and by the detection of elevated major ions (chloride, sodium, magnesium, and calcium) associated, in part, with road-salt applications. Source analysis for chloride indicates mixtures of road salt, water softeners, and sewage.Continuously measured specific conductance values were used as a surrogate for continuously measured chloride concentrations in the groundwater. The estimated chloride concentrations generally were highest in spring and lowest in summer, and occasionally peak during spring melt. Overall, the range of concentrations varied depending on the local thickness and hydraulic conductivity of the aquifer.Water levels and water quality from the countywide groundwater monitoring network were compared to water levels and water-quality results in 1979 from a previous U.S. Geological Survey study. Potentiometric surface maps show areas with

Non-local rheology of stony debris flow propagating over a cohesionless sediment bed

Science.gov (United States)

Lanzoni, Stefano; Gregoretti, Carlo

2016-04-01

Velocity profiles of gravel-water mixtures observed in flume experiments often exhibit a double-slope behavior, with a lower narrower region where the velocity increases slowly, and an upper wider region often exhibiting a nearly linear behavior. Even though the flow can be classified within the grain-inertia regime, the overall profile seems to not conform to the power law (with exponent 1.5) distribution obtained by integrating along the normal to the flow the dispersive stresses envisaged by Bagnold (1954) in his pioneer work. Note that this formulation neglects the contribution to the velocity profile of the quasi-static (frictional) stresses that tend to dominate close to an erodible sediment bottom. The present work investigates the possibility to find out a uniformly valid distribution of shear stress from the bottom to the flow surface. To this aim we follow a heuristic coherence length approach (GDR-MIDI, 2004) similar to the mixing length procedure commonly used to study the atmospheric boundary layer over canopy (see, e.g., Harmann and Finnegan, 2007). A database built on 64 systematic debris flow experiments is used to disclose the general features of velocity profiles that establish within the body of almost steady water-sediment flows and the dependence of transport sediment volumetric concentration on the relevant parameters. The almost steady water-sediment flows considered in the study were generated by releasing a prescribed water discharge on a saturated layer of sediment (specifically, 3 mm gravel, 6 mm gravel, and 3 mm glass spheres) initially placed in a 10 m long and 0.2 m wide laboratory flume. The analysis clearly indicates that stony debris flow conditions characterized the experiments. The mixing length does not result constant, as required by a Bagnold-like profile, but varies gradually, from zero at the flow surface, to a finite value near the erodible bottom. We discuss this structure in terms of shear stress distribution along the

Stabilization of Horseshoe Lake Road using Geofibers and Soil-Sement

Science.gov (United States)

2012-04-03

One solution to reducing the cost of importing gravel in areas where available soils are predominately silts and : sands is to stabilize the local soils with geofibers and synthetic fluids. There have been several studies which : have evaluated impro...

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

International Nuclear Information System (INIS)

Roberts, Anel A.; Shimaoka, Takayuki

2008-01-01

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 3 . Results revealed that even though aggregate content represents 70% of the weight of the material, hydraulic conductivities as low as 6 x 10 -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

Preliminary view of geotechnical properties of soft rocks of Semanggol formation at Pokok Sena, Kedah

Science.gov (United States)

Ahmad, N. R.; Jamin, N. H.

2018-04-01

The research was inspired by series of geological studies on Semanggol formation found exposed at North Perak, South Kedah and North Kedah. The chert unit comprised interbedded chert-shale rocks are the main lithologies sampled in a small-scale outcrop of Pokok Sena area. Black shale materials were also observed associated with these sedimentary rocks. The well-known characteristics of shale that may swell when absorb water and leave shrinkage when dried make the formation weaker when load is applied on it. The presence of organic materials may worsen the condition apart from the other factors such as the history of geological processes and depositional environment. Thus, this research is important to find the preliminary relations of the geotechnical properties of soft rocks and the geological reasoning behind it. Series of basic soil tests and 1-D compression tests were carried out to obtain the soil parameters. The results obtained gave some preliminary insight to mechanical behaviour of these two samples. The black shale and weathered interbedded chert-shale were classified as sandy-clayey-SILT and clayey-silty-SAND respectively. The range of specific gravity of black shale and interbedded chert/shale 2.3 – 2.6 and fall in the common range of shale and chert specific gravity value. In terms of degree of plasticity, the interbedded chert/shale samples exhibit higher plastic degree compared to the black shale samples. Results from oedometer tests showed that black shale samples had higher overburden pressure (Pc) throughout its lifetime compare to weathered interbedded chert-shale, however the compression index (Cc) of black shale were 0.15 – 0.185 which was higher than that found in interbedded chert-shale. The geotechnical properties of these two samples were explained in correlation with their provenance and their history of geological processes involved which predominantly dictated the mechanical behaviour of these two samples.

Local government note: new perspectives of unsealed roads in South Africa

CSIR Research Space (South Africa)

Paige-Green, P

2007-09-01

Full Text Available in most countries. In South Africa they make up more than 75 per cent of the total road network and probably 95 per cent of the low volume road network. Unsealed roads come with various disadvantages over sealed roads, primarily the ongoing... and continual maintenance as well as the accompanying environmental problems. The maintenance, whether grader blading to restore riding quality or replacing the gravel lost under traffic and environmental actions is both costly and disruptive to the normal...

Historical coseismic surface deformation of fluvial gravel deposits, Schafberg fault, Lower Rhine Graben, Germany

Science.gov (United States)

Kübler, Simon; Friedrich, Anke M.; Gold, Ryan D.; Strecker, Manfred R.

2018-03-01

Intraplate earthquakes pose a significant seismic hazard in densely populated rift systems like the Lower Rhine Graben in Central Europe. While the locations of most faults in this region are well known, constraints on their seismogenic potential and earthquake recurrence are limited. In particular, the Holocene deformation history of active faults remains enigmatic. In an exposure excavated across the Schafberg fault in the southwestern Lower Rhine Graben, south of Untermaubach, in the epicentral region of the 1756 Düren earthquake ( M L 6.2), we mapped a complex deformation zone in Holocene fluvial sediments. We document evidence for at least one paleoearthquake that resulted in vertical surface displacement of 1.2 ± 0.2 m. The most recent earthquake is constrained to have occurred after 815 AD, and we have modeled three possible earthquake scenarios constraining the timing of the latest event. Coseismic deformation is characterized by vertical offset of sedimentary contacts distributed over a 10-m-wide central damage zone. Faults were identified where they fracture and offset pebbles in the vertically displaced gravel layers and fracture orientation is consistent with the orientation of the Schafberg fault. This study provides the first constraint on the most recent surface-rupturing earthquake on the Schafberg fault. We cannot rule out that this fault acted as the source of the 1756 Düren earthquake. Our study emphasizes the importance of, and the need for, paleoseismic studies in this and other intracontinental regions, in particular on faults with subtle geomorphic expression that would not typically be recognized as being potentially seismically active. Our study documents textural features in unconsolidated sediment that formed in response to coseismic rupturing of the underlying bedrock fault. We suggest that these features, e.g., abundant oriented transgranular fractures in their context, should be added to the list of criteria used to identify a fault

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

Science.gov (United States)

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

Floodplain inundation response to climate, valley form, and flow regulation on a gravel-bed river in a Mediterranean-climate region

Science.gov (United States)

Cienciala, P.; Pasternack, G. B.

2017-04-01

Floodplain inundation regime defines hydrological connectivity between river channel and floodplain and thus strongly controls structure and function of these highly diverse and productive ecosystems. We combined an extensive LiDAR data set on topography and vegetation, long-term hydrological records, as well as the outputs of hydrological and two-dimensional hydraulic models to examine how floodplain inundation regimes in a dynamic, regulated, gravel-cobble river in a Mediterranean-climate region are controlled by reach-scale valley morphology, hydroclimatic conditions, and flow regulation. Estimated relative differences in the extent, duration, and cumulative duration of inundation events were often as large as an order of magnitude and generally greatest for large and long duration events. The relative impact of flow regulation was greatest under dry hydroclimatic conditions. Although the effects of hydroclimate and flow impairment are larger than that of valley floor topography, the latter controls sensitivity of floodplain hydroperiod to flow regime changes and should not be ignored. These quantitative estimates of the relative importance of factors that control floodplain processes in Mediterranean, semiarid rivers contributes to better understanding of hydrology and geomorphology of this important class of channels. We also discuss implications of our findings for processes that shape floodplain habitat for riparian vegetation and salmonid fish, especially in the context of ecological restoration.

Long-term controls on continental-scale bedrock river terrace deposition from integrated clast and heavy mineral assemblage analysis: An example from the lower Orange River, Namibia

Science.gov (United States)

Nakashole, Albertina N.; Hodgson, David M.; Chapman, Robert J.; Morgan, Dan J.; Jacob, Roger J.

2018-02-01

Establishing relationships between the long-term landscape evolution of drainage basins and the fill of sedimentary basins benefits from analysis of bedrock river terrace deposits. These fragmented detrital archives help to constrain changes in river system character and provenance during sediment transfer from continents (source) to oceans (sink). Thick diamondiferous gravel terrace deposits along the lower Orange River, southern Namibia, provide a rare opportunity to investigate controls on the incision history of a continental-scale bedrock river. Clast assemblage and heavy mineral data from seven localities permit detailed characterisation of the lower Orange River gravel terrace deposits. Two distinct fining-upward gravel terrace deposits are recognised, primarily based on mapped stratigraphic relationships (cross-cutting relationships) and strath and terrace top elevations, and secondarily on the proportion of exotic clasts, referred to as Proto Orange River deposits and Meso Orange River deposits. The older early to middle Miocene Proto Orange River gravels are thick (up to 50 m) and characterised by a dominance of Karoo Supergroup shale and sandstone clasts, whereas the younger Plio-Pleistocene Meso Orange River gravels (6-23 m thick) are characterised by more banded iron formation clasts. Mapping of the downstepping terraces indicates that the Proto gravels were deposited by a higher sinuosity river, and are strongly discordant to the modern Orange River course, whereas the Meso deposits were deposited by a lower sinuosity river. The heavy minerals present in both units comprise magnetite, garnet, amphibole, epidote and ilmenite, with rare titanite and zircon grains. The concentration of amphibole-epidote in the heavy minerals fraction increases from the Proto to the Meso deposits. The decrease in incision depths, recorded by deposit thicknesses above strath terraces, and the differences in clast character (size and roundness) and type between the two

Occurrence of Somma-Vesuvio fine ashes in the tephrostratigraphic record of Panarea, Aeolian Islands

Science.gov (United States)

Donatella, De Rita; Daniela, Dolfi; Corrado, Cimarelli

2008-10-01

Ash-rich tephra layers interbedded in the pyroclastic successions of Panarea island (Aeolian archipelago, Southern Italy) have been analyzed and related to their original volcanic sources. One of these tephra layers is particularly important as it can be correlated by its chemical and morphoscopic characteristics to the explosive activity of Somma-Vesuvio. Correlation with the Pomici di Base eruption, that is considered one of the largest explosive events causing the demolition of the Somma stratovolcano, seems the most probable. The occurrence on Panarea island of fine ashes related to this eruption is of great importance for several reasons: 1) it allows to better constrain the time stratigraphy of the Panarea volcano; 2) it provides a useful tool for tephrochronological studies in southern Italy and finally 3) it allows to improve our knowledge on the distribution of the products of the Pomici di Base eruption giving new insights on the dispersion trajectories of fine ashes from plinian plumes. Other exotic tephra layers interbedded in the Panarea pyroclastic successions have also been found. Chemical and sedimentological characteristics of these layers allow their correlation with local vents from the Aeolian Islands thus constraining the late explosive activity of Panarea dome.

Tectonic implications of the contrasting geochemistry of Damaran mafic volcanic rocks, South West Africa

International Nuclear Information System (INIS)

Miller, R.McG.

1983-01-01

Ortho-amphibolites occur in the southern and central parts of the north-east-trending branch of the Damara Orogen. The Matchless Member amphibolites are interbedded with quartzose mica schist. Mobility of Si, ΣFe, Mn, Mg, Ca, Na, K, P, CO 2 , H 2 O, Rb, Ba, Sr and possibly LREE and immobility of Co, V, Sc, Ga, Zr, Nb, Y and HREE are indicated during metamorphism and reaction with country rock. Central Zone amphibolites are alkaline. The stratigraphically lower amphibolites have a within-plate chemistry; their distribution and associated rock types indicate a continental origin. The Matchless amphibolites have an ocean-floor chemistry. The Damaran sedimentary and orogenic cycle was initiated by continental rifting in three parallel zones in which alkaline acid volcanics occur locally. Widespread subsidence of the rift zones and the intervening areas followed and led to deposition of carbonate and clastic rocks under shallow marine conditions. During renewed rifting, submarine, alkaline basic lavas were extruded. The Southern Margin Zone amphibolites are interbedded with continental slope mixtites and continental rise deep-water fans. Spreading led to continental breakup and the formation of oceanic crust

A 2D hydrodynamic-sedimentological model for gravel bed rivers. Part II, Case study: the Brenta River in Italy

Directory of Open Access Journals (Sweden)

Gabriel Kaless

2013-09-01

Full Text Available A 2D depth average model has been used to simulate water and sediment flow in the Brenta River so as to interpret channel changes and to assess model predictive capabilities. The Brenta River is a gravel bed river located in Northern Italy. The study reach is 1400 long and has a mean slope of 0.0056. High resolution digital terrain models has been produced combining laser imaging detection and ranging data with colour bathymetry techniques. Extensive field sedimentological surveys have been also carried out for surface and subsurface material. The data were loaded in the model and the passage of a high intense flood (R.I. > 9 years was simulated. The model was run under the hypothesis of a substantial equilibrium between sediment input and transport capacity. In this way, the model results were considered as a reference condition, and the potential trend of the reach was assessed. Low-frequency floods (R.I. » 1.5 years are expected to produce negligible changes in the channel while high floods may focalize erosion on banks instead than on channel bed. Furthermore, the model predicts well the location of erosion and siltation areas and the results promote its application to other reaches of the Brenta River in order to assess their stability and medium-term evolution.

Facies analysis, depositional environments and paleoclimate of the Cretaceous Bima Formation in the Gongola Sub - Basin, Northern Benue Trough, NE Nigeria

Science.gov (United States)

Shettima, B.; Abubakar, M. B.; Kuku, A.; Haruna, A. I.

2018-01-01

Facies analysis of the Cretaceous Bima Formation in the Gongola Sub -basin of the Northern Benue Trough northeastern Nigeria indicated that the Lower Bima Member is composed of alluvial fan and braided river facies associations. The alluvial fan depositional environment dominantly consists of debris flow facies that commonly occur as matrix supported conglomerate. This facies is locally associated with grain supported conglomerate and mudstone facies, representing sieve channel and mud flow deposits respectively, and these deposits may account for the proximal alluvial fan region of the Lower Bima Member. The distal fan facies were represented by gravel-bed braided river system of probably Scot - type model. This grade into sandy braided river systems with well developed floodplains facies, forming probably at the lowermost portion of the alluvial fan depositional gradient, where it inter-fingers with basinal facies. In the Middle Bima Member, the facies architecture is dominantly suggestive of deep perennial sand-bed braided river system with thickly developed amalgamated trough crossbedded sandstone facies fining to mudstone. Couplets of shallow channels are also locally common, attesting to the varying topography of the basin. The Upper Bima Member is characterized by shallow perennial sand-bed braided river system composed of successive succession of planar and trough crossbedded sandstone facies associations, and shallower channels of the flashy ephemeral sheetflood sand - bed river systems defined by interbedded succession of small scale trough crossbedded sandstone facies and parallel laminated sandstone facies. The overall stacking pattern of the facies succession of the Bima Formation in the Gongola Sub - basin is generally thinning and fining upwards cycles, indicating scarp retreat and deposition in a relatively passive margin setting. Dominance of kaolinite in the clay mineral fraction of the Bima Formation points to predominance of humid sub - tropical

Field-trip guide to the geology of the Lexington Reservoir and Loma Prieta areas in the Santa Cruz Mountains, Santa Clara and Santa Cruz counties, California

Science.gov (United States)

Stoffer, Philip W.; Messina, Paula

2002-01-01

This guide contains a road log and five stop descriptions for a field trip in the southern Santa Cruz Mountains. The trip officially begins at the boat dock parking area on Alma Bridge Road near the dam of Lexington Reservoir. Stop 1 involves a walk up the Limekiln Trail to examine a large landslide in serpentinite that frequently takes out the trail. Stop 2 is at Miller Point picnic area along the shore of the reservoir where exposures of massive, fractured graywacke sandstone are capped with terrace gravel deposits. Stop 3 is along Highland Way in the Santa Cruz Mountains where large landslides have occasionally force the closure of the road. Stop 4A-C are several closely spaced outcrop areas along Loma Prieta Avenue and Summit-Mt. Madonna Road in the Loma Prieta summit area. A walk to scenic vista points provide opportunity to discuss the evolution of regional landscape along the crest of the Sierra Azul. In addition, a variety of rock types are exposed in the Stop 4 area along a series of road cuts, including Cretaceous age conglomerate, turbidites (consisting of interbedded sandstone and shale), and fossiliferous mudstone. Stop 5 involves returning to the boat dock parking area to examine geology and the placement of the Lexington Dam in the Los Gatos Creek canyon.

Radon in homes of the Portland, Oregon Area: Radon data from local radon testing companies collected by CRM (Continuous Radon Measurement) machines

Science.gov (United States)

Whitney, H.; Lindsey, K.; Linde, T.; Burns, S. F.

2013-12-01

Students from the Department of Geology at Portland State University paired up with the Oregon Health Authority to better understand radon gas values in homes of the Portland metropolitan area. This study focuses on radon values collected by continuous radon measurement (CRM) machines, taken by local radon testing companies. The local companies participating in this study include Alpha Environmental Services, Inc., Cascade Radon, Environmental Works, The House Detectives, LLC, and Soil Solutions Environmental Services, Inc. In total, 2491 radon readings spanning across 77 zip codes were collected from local companies in the Portland metropolitan area. The maximum value, average value, percentage of homes greater than 4 pCi/L and total rank sum was calculated and used to determine the overall radon potential for each zip code (Burns et al., 1998). A list and four maps were produced showing the results from each category. Out of the total records, 24 zip codes resulted in high radon potential and the average reading for the entire Portland Metropolitan area was 3.7 pCi/L. High potential zip codes are thought to be a result of sand and gravel (Missoula Flood deposits) and faults present in the subsurface. The CRM data was compared with both long-term and short-term data provided by the Oregon Health Authority to validate radon potentials in each zip code. If a home is located in a zip code with high or moderate radon potential across two types of data sets, it is recommended that those homes be tested for radon gas.

Central receiver solar thermal power system, Phase 1. CDRL Item 2. Pilot plant preliminary design report. Volume V. Thermal storage subsystem. [Sensible heat storage using Caloria HT43 and mixture of gravel and sand

Energy Technology Data Exchange (ETDEWEB)

Hallet, Jr., R. W.; Gervais, R. L.

1977-10-01

The proposed 100-MWe Commercial Plant Thermal Storage System (TSS) employs sensible heat storage using dual liquid and solid media for the heat storage in each of four tanks, with the thermocline principle applied to provide high-temperature, extractable energy independent of the total energy stored. The 10-MW Pilot Plant employs a similar system except uses only a single tank. The high-temperature organic fluid Caloria HT43 and a rock mixture of river gravel and No. 6 silica sand were selected for heat storage in both systems. The system design, installation, performance testing, safety characteristics, and specifications are described in detail. (WHK)

Paleogene Vertebrate Paleontology, Geology and Remote Sensing in the Wind River Basin

Science.gov (United States)

Stucky, R. K.; Krishtalka, L.

1985-01-01

Biostratigraphic and lithostratigraphic studies were used to correlate different events in the geologic evolution of the northeastern part of the Wind River Basin and have suggested several conclusions. Laterally equivalent exposures of the Lysite member from Cedar Ridge to Bridger Creek show a gradation in lithology from interbedded boulder conglomerates and sandstones to interbedded lenticular sandstones and mudstones to interbedded carbonaceous shales, coals and tabular sandstones. This gradation suggests a shift from alluvial fan to braided stream to paludal or lacustrine sedimentary environments during the late early Eocene. The Lysite and Lost Cabin members of the Wind River Formation are in fault contact in the Bridger Creek area and may intertongue to the east along Cedar Ridge. Ways in which remote sensing could be used in these studies are discussed.

Revegetation in abandoned quarries with landfill stabilized waste and gravels: water dynamics and plant growth - a case study

Science.gov (United States)

Zhang, Cheng-liang; Feng, Jing-jing; Rong, Li-ming; Zhao, Ting-ning

2017-11-01

Large amounts of quarry wastes are produced during quarrying. Though quarry wastes are commonly used in pavement construction and concrete production, in situ utilization during ecological restoration of abandoned quarries has the advantage of simplicity. In this paper, rock fragments 2-3 cm in size were mixed with landfill stabilized waste (LSW) in different proportions (LSW : gravel, RL), which was called LGM. The water content, runoff and plant growth under natural precipitation were monitored for 2 years using a runoff plot experiment. LGM with a low fraction of LSW was compacted to different degrees to achieve an appropriate porosity; water dynamics and plant growth of compacted LGM were studied in a field experiment. The results showed the following: (1) LGM can be used during restoration in abandoned quarries as growing material for plants. (2) RL had a significant effect on the infiltration and water-holding capacity of LGM and thus influenced the retention of precipitation, water condition and plant growth. LGM with RL ranging from 8:1 to 3:7 was suitable for plant growth, and the target species grew best when RL was 5:5. (3) Compaction significantly enhanced water content of LGM with a low RL of 2:8, but leaf water content of plants was lower or unchanged in the more compacted plots. Moderate compaction was beneficial to the survival and growth of Robinia pseudoacacia L. Platycladus orientalis (L.) Franco and Medicago sativa L. were not significantly affected by compaction, and they grew better under a high degree of compaction, which was disadvantageous for the uppermost layer of vegetation.

75 FR 29686 - Proposed Establishment of the Pine Mountain-Mayacmas Viticultural Area

Science.gov (United States)

2010-05-27

... states that local growers report that Pine Mountain vineyards are naturally free of mildew, a vineyard... often stall over Pine Mountain and the Mayacmas range, dropping more rain than in other areas. Pine..., these mountain soils include large amounts of sand and gravel. Pine Mountain soils are generally less...

Removal of waterborne bacteria from surface water and ...

African Journals Online (AJOL)

In this study 5 household water-treatment devices/systems (HWTS) were constructed using inexpensive local materials (sand, gravel, zeolites and clays). They included the silver-impregnated porous pot filter (SIPP), the ceramic candle filter (CCF), the conventional biosand filter (BSF-S), a modified biosand filter with zeolites ...

Building stones from a muddy delta: Native natural stone from The Netherlands

NARCIS (Netherlands)

Nijland, T.G.; Dubelaar, C.W.; Tolboom, H.J.; Hees, R.P.J. van

2006-01-01

Most of the Netherlands a Quaternary delta, local supplies of natural stone suitable for building are rare. These include: Quaternary bog iron ores used in early medieval times (until c. 1200); erratics, deposited in boulder clay during the Saalian ice age in the northern Netherlands and gravel from

A finite volume solver for three dimensional debris flow simulations based on a single calibration parameter

Science.gov (United States)

von Boetticher, Albrecht; Turowski, Jens M.; McArdell, Brian; Rickenmann, Dieter

2016-04-01

Debris flows are frequent natural hazards that cause massive damage. A wide range of debris flow models try to cover the complex flow behavior that arises from the inhomogeneous material mixture of water with clay, silt, sand, and gravel. The energy dissipation between moving grains depends on grain collisions and tangential friction, and the viscosity of the interstitial fine material suspension depends on the shear gradient. Thus a rheology description needs to be sensitive to the local pressure and shear rate, making the three-dimensional flow structure a key issue for flows in complex terrain. Furthermore, the momentum exchange between the granular and fluid phases should account for the presence of larger particles. We model the fine material suspension with a Herschel-Bulkley rheology law, and represent the gravel with the Coulomb-viscoplastic rheology of Domnik & Pudasaini (Domnik et al. 2013). Both composites are described by two phases that can mix; a third phase accounting for the air is kept separate to account for the free surface. The fluid dynamics are solved in three dimensions using the finite volume open-source code OpenFOAM. Computational costs are kept reasonable by using the Volume of Fluid method to solve only one phase-averaged system of Navier-Stokes equations. The Herschel-Bulkley parameters are modeled as a function of water content, volumetric solid concentration of the mixture, clay content and its mineral composition (Coussot et al. 1989, Yu et al. 2013). The gravel phase properties needed for the Coulomb-viscoplastic rheology are defined by the angle of repose of the gravel. In addition to this basic setup, larger grains and the corresponding grain collisions can be introduced by a coupled Lagrangian particle simulation. Based on the local Savage number a diffusive term in the gravel phase can activate phase separation. The resulting model can reproduce the sensitivity of the debris flow to water content and channel bed roughness, as

Lower Brioverian formations (Upper Proterozoic) of the Armorican Massif (France): geodynamic evolution of source areas revealed by sandstone petrography and geochemistry

Science.gov (United States)

Dabard, Marie Pierre

1990-11-01

Formations with interbedded cherts constitute an important part of the Lower Brioverian succession (Upper Proterozoic age) in the Armorican Massif (northwest France). These formations are composed of shale-sandstone alternations with interbedded siliceous carbonaceous members. Petrographic and geochemical study of the detrital facies shows that these rocks are compositionally immature. The wackes are rich in lithic fragments (volcanic fragments: 3-20% modal; sedimentary and metamorphic fragments: 0-7% modal) and in feldspar (5-16%). From the geochemical point of view, they are relatively enriched in Fe 2+MgO (about 5.5%) and in alkalis with {Na 2O }/{K 2O } ratios greater than 1. The CaO contents are low (about 0.3%). Slightly negative Eu anomalies are observed ( {Eu}/{Eu ∗} = 0.8 ). Their chemical compositions are in agreement with a dominantly acidic source area with deposition in a continental active margin setting. Compared with other Upper Proterozoic deposits of the Armorican Massif, the interbedded-chert formations appear rather similar to other deposits in North Brittany which accumulated in an intra-arc or back-arc basin environment. The formations with interbedded cherts are interpreted as having been deposited during an early stage of magmatic arc activity (around 640-630 Ma ago) in an immature marginal basin. The clastic supply to these formations is derived in part from early volcanic products (acidic to intermediate) which are linked to subduction beneath the North Armorican Domain. Another component is inherited from the reworking of 2000 Ma old basement relics. The opening of the back-arc domain, with associated basaltic volcanism, would bring about a progressive displacement of the interbedded-chert depositional basin towards the continental margin.

Recharge sources and geochemical evolution of groundwater in the Quaternary aquifer at Atfih area, the northeastern Nile Valley, Egypt

Science.gov (United States)

El-Sayed, Salah Abdelwahab; Morsy, Samah M.; Zakaria, Khalid M.

2018-06-01

This study addresses the topic of recharge sources and evolution of groundwater in the Atfih area situated in the northeastern part of the Nile Valley, Egypt. Inventory of water wells and collection of groundwater and surface water samples have been achieved. Water samples are analyzed for major ions according to the American Society for Testing and Materials and for the environmental isotopes analysis (oxygen-18 and deuterium) by using a Triple Liquid Isotopic Water Analyzer (Los Gatos). The groundwater is available from the Quaternary aquifer formed mainly of graded sand and gravel interbedded with clay lenses. The hydrogeologic, hydrogeochemical and isotopic investigations indicate the hydrodynamic nature of the aquifer, where different flow paths, recharge sources and evolution mechanisms are distinguished. The directions of groundwater flow are from E, W and S directions suggesting the contribution from Nile River, the Eocene aquifer and the Nile basin, respectively. The groundwater altitudes range from 13 m (MSL) to 44 m (MSL). The hydraulic gradient varies between 0.025 and 0.0015. The groundwater is alkaline (pH > 7) and has salinity ranging from fresh to brackish water (TDS between 528 mg/l and 6070 mg/l). The observed wide range in the ionic composition and water types reflects the effect of different environmental and geological conditions through which the water has flowed. The isotopic compositions of groundwater samples vary between -14.13‰ and +23.56 for δD and between - 2.91‰ and +3.10 for δ18O. The isotopic data indicates that the Quaternary aquifer receive recharge from different sources including the Recent Nile water, surplus irrigation water, old Nile water before the construction of Aswan High Dam, surface runoff of local rains and Eocene aquifer. Evaporation, water rock interaction and mixing between different types of waters are the main processes in the groundwater evolution. Major suggestions are presented to develop the aquifer

Soft-sediment deformation in a tectonically active area: The Plio-Pleistocene Zarzal Formation in the Cauca Valley (Western Colombia)

Science.gov (United States)

Neuwerth, Ralph; Suter, Fiore; Guzman, Carlos A.; Gorin, Georges E.

2006-04-01

The Plio-Pleistocene Zarzal Formation corresponds to fluvio-lacustrine sediments deposited in an intramontane depression within the Colombian Andes, associated with the Cauca-Romeral Fault System. It crops out mainly in the Cauca Valley where numerous field sections have permitted the mapping of the vertical and lateral lithological variations. Lacustrine deposits of sands, silts, clays and diatomites are interbedded with fluvial sand and gravel beds and fluvio-volcanic mass flows derived from the volcanic Central Cordillera. Numerous soft-sediment deformation structures are encountered in this formation, particularly in fine- to medium-grained sands, silts and clays: load structures (load casts, flame structures, pseudonodules), water escape structures (water escape cusps, dish-and-pillar and pocket-and-pillar structures), soft-sediment intrusions (clastic sills and dykes), disturbed laminites, convolute laminations, slumps and synsedimentary faulting. Deformation mechanisms and driving forces are related essentially to gravitational instabilities, dewatering, liquidization and brittle deformations. Field and regional geological data show that most of these deformations are related to seismicity and can be interpreted as seismites. This area has a geological and recent seismic history and outcrops show both syn- and post-depositional faulting related to the transpressional regime of this part of the Colombian Andes, which generates strike-slip faults and associated local normal faults. The drainage pattern within the Zarzal Formation shows the signature of neotectonics. Moreover, the fine to coarse-grained sands of the Zarzal Formation are lithologies prone to liquefaction when affected by seismic waves. The intercalation of the deformed intervals within undisturbed strata confirms the catastrophic nature of the events. Finally, the large areal extent of the deformations and the type of structures are compatible with seismites. Consequently, the existence of

Beyond the threshold for motion: river channel geometry and grain size reflect sediment supply

Science.gov (United States)

Pfeiffer, A.; Finnegan, N. J.; Willenbring, J. K.

2016-12-01

In many gravel-bedded rivers, floods that fill the ch­­annel banks create just enough shear stress to move the median-sized gravel particles on the bed surface (D50). Because this observation is common and is supported by theory, the coincidence of bankfull flow and the incipient motion of D50 has become a­­ commonly employed assumption. However, not all natural gravel channels actually conform to this simple relationship; some channels maintain bankfull stresses far in excess of the critical stress required to initiate sediment transport. We use a database of >300 gravel-bedded rivers and >600 10Be-derived erosion rates from across North America to explore the hypothesis that sediment supply drives the magnitude of bankfull shear stress relative to the critical stress required to mobilize the median bed surface grain size. We find that the ratio of bankfull to critical stress is significantly higher in West Coast river reaches (2.47, n= 84) than in river reaches in the rest of the continent (1.03, n = 245). This pattern parallels trends in erosion rates (and hence sediment supplies). Supporting our hypothesis, we find a significant correlation between upstream erosion rate and local τ*bf/τ*c at sites where this comparison is possible. Our analysis reveals a decrease in bed surface armoring with increasing τ*bf/τ*c, suggesting that channels accommodate changes in sediment supply through adjustments in bed surface grain size, as predicted through numerical modeling. Our findings demonstrate that sediment supply is encoded in the bankfull hydraulic geometry of gravel-bedded channels through its control on bed surface grain size.

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

Science.gov (United States)

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.

Dust emissions from unpaved roads on the Colorado Plateau

Science.gov (United States)

Duniway, M.; Flagg, C.; Belnap, J.

2013-12-01

On the Colorado Plateau, elevated levels of aeolian dust have become a major land management and policy concern due to its influence on climate, weather, terrestrial ecosystem dynamics, landscape development and fertility, melting of snow and ice, air quality, and human health. Most desert soil surfaces are stabilized by plants, rocks, and/or physical or biological soil crusts, but once disturbed, sediment production from these surfaces can increase dramatically. Road development and use is a common surface disturbing activity in the region. The extent and density of roads and road networks is rapidly increasing due to continued energy exploration, infrastructure development, and off-highway recreation activities. Though it is well known that unpaved roads produce dust, the relative contribution of dust from existing roads or the implications of future road development to regional dust loading is unknown. To address this need, we have initiated a multifaceted research effort to evaluating dust emissions from unpaved roads regionally. At 34 sites arranged across various road surfaces and soil textures in southeastern Utah, we are: 1) monitoring dust emissions, local wind conditions, and vehicle traffic and 2) evaluating fugitive dust potential using a portable wind tunnel and measuring road characteristics that affect dust production. We will then 3) develop a GIS-based model that integrates results from 1 & 2 to estimate potential dust contributions from current and future scenarios of regional road development. Passive, horizontal sediment traps were installed at three distances downwind from the road edge. One control trap was placed upwind of the samplers to account for local, non-road dust emissions. An electronic vehicle counter and anemometer were also installed at monitoring sites. Dust samples were collected every three months at fixed heights, 15 cm up to 100 cm above the soil surface, from March 2010 to the present. Threshold friction velocities (TFV

Development of Decontamination Process for Soil Contaminated Uranium

International Nuclear Information System (INIS)

Kim, Gye-Nam; Kim, Seung-Soo; Park, Uk-Rang; Han, Gyu-Seong; Moon, Jei-Kwon

2014-01-01

Various experiments with full-scaled electrokinetic equipment, soil washing equipment, and gravel washing equipment were performed to remove 238 U from contaminated soils of below 0.4 Bq/g. The repetition number and the removal efficiencies of the soil and gravel washing equipment were evaluated. The decontamination periods by the soil and gravel electrokinetic equipment were evaluated. Finally, a work process of full-scaled decontamination equipment was developed. Contaminated soils were classified into soils and gravels using a 8.0 cm sieve. Soils were sent to the soil washing equipment, while gravels were sent to the gravel washing equipment. Soils sent to the soil washing equipment were sent to the soil electrokinetic equipment after soil washing. A repetition number of soil washing was two times. The washed gravels were sent to the gravel electrokinetic equipment. Gravel contaminated with a high concentration requires crushing after gravel washing

Development of Decontamination Process for Soil Contaminated Uranium

Energy Technology Data Exchange (ETDEWEB)

Kim, Gye-Nam; Kim, Seung-Soo; Park, Uk-Rang; Han, Gyu-Seong; Moon, Jei-Kwon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-10-15

Various experiments with full-scaled electrokinetic equipment, soil washing equipment, and gravel washing equipment were performed to remove {sup 238}U from contaminated soils of below 0.4 Bq/g. The repetition number and the removal efficiencies of the soil and gravel washing equipment were evaluated. The decontamination periods by the soil and gravel electrokinetic equipment were evaluated. Finally, a work process of full-scaled decontamination equipment was developed. Contaminated soils were classified into soils and gravels using a 8.0 cm sieve. Soils were sent to the soil washing equipment, while gravels were sent to the gravel washing equipment. Soils sent to the soil washing equipment were sent to the soil electrokinetic equipment after soil washing. A repetition number of soil washing was two times. The washed gravels were sent to the gravel electrokinetic equipment. Gravel contaminated with a high concentration requires crushing after gravel washing.

Suitability of parametric models to describe the hydraulic properties of an unsaturated coarse sand and gravel

Science.gov (United States)

Mace, Andy; Rudolph, David L.; Kachanoski , R. Gary

1998-01-01

The performance of parametric models used to describe soil water retention (SWR) properties and predict unsaturated hydraulic conductivity (K) as a function of volumetric water content (θ) is examined using SWR and K(θ) data for coarse sand and gravel sediments. Six 70 cm long, 10 cm diameter cores of glacial outwash were instrumented at eight depths with porous cup ten-siometers and time domain reflectometry probes to measure soil water pressure head (h) and θ, respectively, for seven unsaturated and one saturated steady-state flow conditions. Forty-two θ(h) and K(θ) relationships were measured from the infiltration tests on the cores. Of the four SWR models compared in the analysis, the van Genuchten (1980) equation with parameters m and n restricted according to the Mualem (m = 1 - 1/n) criterion is best suited to describe the θ(h) relationships. The accuracy of two models that predict K(θ) using parameter values derived from the SWR models was also evaluated. The model developed by van Genuchten (1980) based on the theoretical expression of Mualem (1976) predicted K(θ) more accurately than the van Genuchten (1980) model based on the theory of Burdine (1953). A sensitivity analysis shows that more accurate predictions of K(θ) are achieved using SWR model parameters derived with residual water content (θr) specified according to independent measurements of θ at values of h where θ/h ∼ 0 rather than model-fit θr values. The accuracy of the model K(θ) function improves markedly when at least one value of unsaturated K is used to scale the K(θ) function predicted using the saturated K. The results of this investigation indicate that the hydraulic properties of coarse-grained sediments can be accurately described using the parametric models. In addition, data collection efforts should focus on measuring at least one value of unsaturated hydraulic conductivity and as complete a set of SWR data as possible, particularly in the dry range.

Breakup and reestablishment of the armour layer in a large gravel-bed river below dams: The lower Ebro

Science.gov (United States)

Vericat, Damia; Batalla, Ramon J.; Garcia, Celso

2006-06-01

Changes in armour layer during floods under supply limited conditions are little known. This paper describes the breakup and the reestablishment of the bed armour layer in the regulated gravel-bed Ebro River during a flooding period. The study was conducted over a 28-km study reach from 2002 to 2004. The surface, subsurface and bed load grain size distribution constitute the bases for the analysis of bed-armouring dynamics. The results indicate that the magnitude of floods controlled the degree of armouring of the river bed. The initial mean armouring ratio was 2.3, with maximum values reaching 4.4. Floods in the winter of 2002-2003 ( Q8) caused the breakup of the armour layer in several sections. This resulted in the erratic bed load pattern observed during the December 2002 flushing flow and in the increase in bed load transport during successive events. Most grain size classes were entrained and transported, causing river bed incision. The mean armouring ratio decreased to 1.9. In contrast, during low magnitude floods in 2003-2004 ( Q2), the coarsest fractions (64 mm) did not take part in the bed load while finer particles were winnowed, thus surface deposits coarsened. As a result, the armour layer was reestablished (i.e., the mean armouring ratio increased to 2.3), and the supply of subsurface sediment decreased. The supply and transport of bed material appear to be in balance in the river reach immediately below the dam. In contrast, the transport of medium and finer size classes in the downstream reaches was higher than their supply from upstream, a phenomenon that progressively reduced their availability in the river bed surface, hence the armour layer reworking.

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

Energy Technology Data Exchange (ETDEWEB)

NONE

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.

Origin, Extent, and Thickness of Quaternary Geologic Units in the Willamette Valley, Oregon

Science.gov (United States)

O'Connor, Jim E.; Sarna-Wojcicki, Andrei M.; Wozniak, Karl C.; Polette, Danial J.; Fleck, Robert J.

2001-01-01

Stratigraphic and chronologic information collected for Quaternary deposits in the Willamette Valley, Oregon, provides a revised stratigraphic framework that serves as a basis for a 1:250,000-scale map, as well as for thickness estimates of widespread Quaternary geologic units. We have mapped 11 separate Quaternary units that are differentiated on the basis of stratigraphic, topographic, pedogenic, and hydrogeologic properties. In summation, these units reflect four distinct episodes in the Quaternary geologic development of the Willamette Valley: 1) Fluvial sands and gravels that underlie terraces flanking lowland margins and tributary valleys were probably deposited between 2.5 and 0.5 million years ago. They are the oldest widespread surficial Quaternary deposits in the valley. Their present positions and preservation are undoubtedly due to postdepositional tectonic deformation - either by direct tectonic uplift of valley margins, or by regional tectonic controls on local base level. 2) Tertiary and Quaternary excavation or tectonic lowering of the Willamette Valley accommodated as much as 500 m (meters) of lacustrine and fluvial fill. Beneath the lowland floor, much of the upper 10 to 50 m of fill is Quaternary sand and gravel deposited by braided channel systems in subhorizontal sheets 2 to 10 m thick. These deposits grade to gravel fans 40 to 100 m thick where major Cascade Range rivers enter the valley and are traced farther upstream as much thinner valley trains of coarse gravel. The sand and gravel deposits have ages that range from greater than 420,000 to about 12,000 years old. A widely distributed layer of sand and gravel deposited at about 12 ka (kiloannum, thousands of years before the present) is looser and probably more permeable than older sand and gravel. Stratigraphic exposures and drillers' logs indicate that this late Pleistocene unit is mostly between 5 and 20 m thick where it has not been subsequently eroded by the Willamette River and its

Performance analysis of double basin solar still with evacuated tubes

International Nuclear Information System (INIS)

Hitesh N Panchal; Shah, P. K.

2013-01-01

Solar still is a very simple device, which is used for solar distillation process. In this research work, double basin solar still is made from locally available materials. Double basin solar still is made in such a way that, outer basin is exposed to sun and lower side of inner basin is directly connected with evacuated tubes to increase distillate output and reducing heat losses of a solar still. The overall size of the lower basin is about 1006 mm x 325 mm x 380 mm, the outer basin is about 1006 mm x 536 mm x 100 mm Black granite gravel is used to increase distillate output by reducing quantity of brackish or saline water in the both basins. Several experiments have conducted to determine the performance of a solar still in climate conditions of Mehsana (latitude of 23 degree 59' and longitude of 72 degree 38'), Gujarat, like a double basin solar still alone, double basin solar still with different size black granite gravel, double basin solar still with evacuated tubes and double basin solar still with evacuated tubes and different size black granite gravel. Experimental results show that, connecting evacuated tubes with the lower side of the inner basin increases daily distillate output of 56% and is increased by 60%, 63% and 67% with average 10 mm, 20 mm and 30 mm size black granite gravel. Economic analysis of present double basin solar still is 195 days. (authors)

Three-Dimensional Geological Model of Quaternary Sediments in Walworth County, Wisconsin, USA

Directory of Open Access Journals (Sweden)

Jodi Lau

2016-07-01

Full Text Available A three-dimensional (3D geologic model was developed for Quaternary deposits in southern Walworth County, WI using Petrel, a software package primarily designed for use in the energy industry. The purpose of this research was to better delineate and characterize the shallow glacial deposits, which include multiple shallow sand and gravel aquifers. The 3D model of Walworth County was constructed using datasets such as the U.S. Geological Survey 30 m digital elevation model (DEM of land surface, published maps of the regional surficial geology and bedrock topography, and a database of water-well records. Using 3D visualization and interpretation tools, more than 1400 lithostratigraphic picks were efficiently interpreted amongst 725 well records. The final 3D geologic model consisted of six Quaternary lithostratigraphic units and a bedrock horizon as the model base. The Quaternary units include in stratigraphic order from youngest to oldest: the New Berlin Member of the Holy Hill Formation, the Tiskilwa Member of the Zenda Formation, a Sub-Tiskilwa Sand/Gravel unit, the Walworth Formation, a Sub-Walworth Sand/Gravel unit, and a Pre-Illinoisan unit. Compared to previous studies, the results of this study indicate a more detailed distribution, thickness, and interconnectivity between shallow sand and gravel aquifers and their connectivity to shallow bedrock aquifers. This study can also help understand uncertainty within previous local groundwater-flow modeling studies and improve future studies.

Revegetation in abandoned quarries with landfill stabilized waste and gravels: water dynamics and plant growth – a case study

Directory of Open Access Journals (Sweden)

C.-L. Zhang

2017-11-01

Full Text Available Large amounts of quarry wastes are produced during quarrying. Though quarry wastes are commonly used in pavement construction and concrete production, in situ utilization during ecological restoration of abandoned quarries has the advantage of simplicity. In this paper, rock fragments 2–3 cm in size were mixed with landfill stabilized waste (LSW in different proportions (LSW : gravel, RL, which was called LGM. The water content, runoff and plant growth under natural precipitation were monitored for 2 years using a runoff plot experiment. LGM with a low fraction of LSW was compacted to different degrees to achieve an appropriate porosity; water dynamics and plant growth of compacted LGM were studied in a field experiment. The results showed the following: (1 LGM can be used during restoration in abandoned quarries as growing material for plants. (2 RL had a significant effect on the infiltration and water-holding capacity of LGM and thus influenced the retention of precipitation, water condition and plant growth. LGM with RL ranging from 8:1 to 3:7 was suitable for plant growth, and the target species grew best when RL was 5:5. (3 Compaction significantly enhanced water content of LGM with a low RL of 2:8, but leaf water content of plants was lower or unchanged in the more compacted plots. Moderate compaction was beneficial to the survival and growth of Robinia pseudoacacia L. Platycladus orientalis (L. Franco and Medicago sativa L. were not significantly affected by compaction, and they grew better under a high degree of compaction, which was disadvantageous for the uppermost layer of vegetation.

Description and analysis of the geohydrologic system in western Pinal County, Arizona

Science.gov (United States)

Hardt, W.F.; Cattany, R.E.

1965-01-01

hydrologic bedrock unit, referred to in this report as the Casa Grande ridge. The ridge trends in a north-south direction from the Sacaton to the Silver Reef Mountains. The unconsolidated deposits constitute the main storage reservoir for ground water in western Pins/ County. The deposits are divided into four units---the local gravel unit, the lower sand and gravel unit, the silt and clay unit, and the upper sand and gravel unit--all of which are major water-yielding units except the silt and clay unit. The local gravel unit, which is present only in the western section of the lower Santa Cruz basin, ranges in thickness from 0 to nearly 1,000 feet and is generally a productive aquifer. The lower sand and gravel unit, Which is a heterogeneous mixture of sand, gravel, and clay, ranges in thickness from 0 to about 500 feet. Where the lower sand and gravel unit is overlain by the silt and clay unit, it generally contains water under artesian conditions; where it is not overlain by the silt and clay unit, it is indistinguishable from the upper sand and gravel unit, and the water is under water-table conditions. The silt and clay unit is the least permeable deposit of the unconsolidated alluvium, and ranges in thickness from 0 to about 2, 000 feet. Generally it is less productive than the other units of the unconsolidated alluvium, although it yields moderate amounts of water from numerous thin stringers and lenses of highly permeable sand and gravel. The upper sand and gravel unit is at the land surface in most of the area; it ranges in thickness from less than 50 to about 600 feet. The unit has the highest average permeability of all the unconsolidated alluvial units; however, the permeability of the unit varies vertically and laterally, which results in a wide range of well yields. As of 1964, the static water levels in most wells in the basin were still in the upper sand and gravel unit. However, the unit is being dewatered in most of the basin, and water levels in

A new model for turbidity current behavior based on integration of flow monitoring and precision coring in a submarine canyon

Science.gov (United States)

Symons, William O.; Sumner, Esther J.; Paull, Charles K.; Cartigny, Matthieu J.B.; Xu, Jingping; Maier, Katherine L.; Lorenson, Thomas; Talling, Peter J.

2017-01-01

Submarine turbidity currents create some of the largest sediment accumulations on Earth, yet there are few direct measurements of these flows. Instead, most of our understanding of turbidity currents results from analyzing their deposits in the sedimentary record. However, the lack of direct flow measurements means that there is considerable debate regarding how to interpret flow properties from ancient deposits. This novel study combines detailed flow monitoring with unusually precisely located cores at different heights, and multiple locations, within the Monterey submarine canyon, offshore California, USA. Dating demonstrates that the cores include the time interval that flows were monitored in the canyon, albeit individual layers cannot be tied to specific flows. There is good correlation between grain sizes collected by traps within the flow and grain sizes measured in cores from similar heights on the canyon walls. Synthesis of flow and deposit data suggests that turbidity currents sourced from the upper reaches of Monterey Canyon comprise three flow phases. Initially, a thin (38–50 m) powerful flow in the upper canyon can transport, tilt, and break the most proximal moorings and deposit chaotic sands and gravel on the canyon floor. The initially thin flow front then thickens and deposits interbedded sands and silty muds on the canyon walls as much as 62 m above the canyon floor. Finally, the flow thickens along its length, thus lofting silty mud and depositing it at greater altitudes than the previous deposits and in excess of 70 m altitude.

Mixed carbonate-siliciclastic sedimentation on a tectonically active margin: Example from the Pliocene of Baja California Sur, Mexico

Science.gov (United States)

Dorsey, Rebecca J.; Kidwell, Susan M.

1999-10-01

Bioclast-rich, coarse-grained deposits in the Pliocene Loreto basin provide a record of mixed carbonate and siliciclastic sedimentation at the steep hanging-wall margin of this small, fault-controlled basin. Sedimentary facies consist of sand- to gravel-sized carbonate debris mixed with volcaniclastic sand and gravel in a proximal to distal facies tract that includes matrix-rich and matrix-poor shelly conglomerate, impure calcirudite and calcarenite, mixed-composition turbidites, and bioturbated calcarenitic sandstone. Carbonate material was produced by mollusks and other benthic organisms on a narrow, high-energy shelf and mixed with volcaniclastic sand and gravel in cross-shelf channels. These mixtures were transported down a steep subaqueous slope by debris flows, grain flows, and turbidity currents, forming foresets and bottomsets of marine Gilbert-type deltas. This style of mixed carbonate-siliciclastic sedimentation has not been documented in detail elsewhere but should be locally abundant in the stratigraphic record of fault-bounded basins, particularly those with cool or nutrient-rich waters that support relatively few binding and framework-building faunas. Recognition of similar facies in other settings can provide useful insights into ancient conditions of carbonate production, oceanography, climate, and tectonics.

Geomorphic Effects, Chronologies, and Archaeological Significance of El Nino Floods in Southern Peru

Science.gov (United States)

Magilligan, F. J.; Manners, R.; Goldstein, P.

2003-12-01

The catastrophic effects of large floods have been well documented, on both contemporary and paleo-timecales, especially for the conterminous U.S. Less is known, however, about extreme events in hyper-arid sub-tropical climates where synoptic scale meteorological causes, such as El Nino-Southern Oscillation events, are the driving atmospheric mechanism. This research documents the geomorphic effects of extreme floods in the Moquegua River valley of southern Peru, in the core of the Atacama Desert. Using a combination of geomorphic mapping, hydrolologic modeling, aerial photography, ASTER satellite imagery, and GIS, we document the geomorphic signature of large contemporary floods within the mid-valley section (1500 masl) of the Rio Moquegua. Stratigraphic evidence and paleostage indicators of paleofloods, such as slackwater deposits and preserved high level flood gravels, are used to evidence late Holocene paleoflood magnitude-frequency relationships. On contemporary timescales, channel belt expansion by lateral erosion during large floods, such as the recent '97 and '98 floods, correspond to as much as 30-40 hectares of floodplain loss along the 20 km study reach. Sixty years of repeat aerial photography indicates that channel belt expansion and floodplain erosion commonly occurs along the Rio Moquegua. The frequent resetting of floodplain alluvium conditioned by these large floods is supported by radiocarbon dating of floodplain exposures. These dates indicate that most of the contemporary floodplain alluvium is younger that 560 14C yrs BP. The highest terrace remnants date to 3250 14C yrs BP and record a series of overbank flood gravels. Evidence for the regionally extensive Miraflores ENSO flood, ca. 1300 AD, exists in tributary and along mainstem sections. This flood has been documented along the coasts of Northern Chile to northern Peru, and has been evoked to explain significant social collapse. Our field evidence indicates that it catastrophically affected

Thermal Variability in Gravel Bars and its Potential Consequences for CO2 Evasion from Alpine Coldwater Streams

Science.gov (United States)

Boodoo, K. S.; Schelker, J.; Battin, T. J.

2016-12-01

Gravel bars (GB) are ubiquitous in-stream structures with relatively large exposed surfaces, capable of absorbing heat and possibly acting as a heat source to the underlying hyporheic zone (HZ). The distinctive mixing of groundwater and surface water within their HZ largely determines its characteristic physical and biogeochemical properties, including temperature distribution. To study thermal variability within GBs and its possible consequences for CO2 evasion fluxes we analysed high frequency spatio-temporal data for a range of stream and atmospheric physical parameters including the vertical GB temperature, in an Alpine cold water stream (Oberer Seebach, Austria) over the course of a year. We found the vertical temperature profiles within the GB to vary seasonally and with discharge. During warm summer months, diurnal vertical temperature patterns were most pronounced and were detected throughout all one-meter-depth profiles. Furthermore, permanently wetted GB sediment (-56 cm depth) temperatures above that of stream and groundwater occurred 17% of the year, particularly during summer. This is further evidence for downward heat transfer to the wetted HZ. Average CO2 flux from the GB was significantly higher than that of streamwater during summer and winter, with significantly higher temperatures and CO2 outgassing rates occurring at the GB tail as compared to streamwater and the head and mid of the GB throughout the year. Higher cumulative (over 6 h) GB temperatures were associated with increased CO2 evasion fluxes; the strength of the relationship increased with depth (max. r2 = 0.61 at -100cm depth). This enhanced CO2 flux may result from the input of warmer CO2-rich groundwater into the HZ in autumn and winter, while downward heat transfer in summer may enhance GB metabolism and therefore CO2 evasion. The importance of these processes is likely to increase, particularly in cold-water streams, due to the occurrence of more frequent and intense warm

Evolution of Fine-Grained Channel Margin Deposits behind Large Woody Debris in an Experimental Gravel-Bed Flume

Science.gov (United States)

ONeill, B.; Marks, S.; Skalak, K.; Puleo, J. A.; Wilcock, P. R.; Pizzuto, J. E.

2014-12-01

Fine grained channel margin (FGCM) deposits of the South River, Virginia sequester a substantial volume of fine-grained sediment behind large woody debris (LWD). FGCM deposits were created in a laboratory setting meant to simulate the South River environment using a recirculating flume (15m long by 0.6m wide) with a fixed gravel bed and adjustable slope (set to 0.0067) to determine how fine sediment is transported and deposited behind LWD. Two model LWD structures were placed 3.7 m apart on opposite sides of the flume. A wire mesh screen with attached wooden dowels simulated LWD with an upstream facing rootwad. Six experiments with three different discharge rates, each with low and high sediment concentrations, were run. Suspended sediment was very fine grained (median grain size of 3 phi) and well sorted (0.45 phi) sand. Upstream of the wood, water depths averaged about 0.08m, velocities averaged about 0.3 m/s, and Froude numbers averaged around 0.3. Downstream of the first LWD structure, velocities were reduced tenfold. Small amounts of sediment passed through the rootwad and fell out of suspension in the area of reduced flow behind LWD, but most of the sediment was carried around the LWD by the main flow and then behind the LWD by a recirculating eddy current. Upstream migrating dunes formed behind LWD due to recirculating flow, similar to reattachment bars documented in bedrock canyon rivers partially obstructed by debouching debris fans. These upstream migrating dunes began at the reattachment point and merged with deposits formed from sediment transported through the rootwad. Downstream migrating dunes formed along the channel margin behind the LWD, downstream of the reattachment point. FGCM deposits were about 3 m long, with average widths of about 0.8 m. Greater sediment concentration created thicker FGCM deposits, and higher flows eroded the sides of the deposits, reducing their widths.

The effect of wet-dry weathering on the rate of bedrock river channel erosion by saltating gravel

Science.gov (United States)

Inoue, Takuya; Yamaguchi, Satomi; Nelson, Jonathan M.

2017-01-01

Previous work has shown that the bedrock erosion rate E because of collisions of saltating bedload can be expressed by E = βqb(1-Pc), where qb is the sediment transport rate, Pc is the extent of alluvial cover, and β is the abrasion coefficient. However, the dependence of the abrasion coefficient on the physical characteristics of the bedrock material is poorly known, and in particular, the effects of wet-dry weathering on the saltation-abrasion bedrock incision has not been specifically characterized. Observation suggests that the typical wet-dry cycling of exposed bedrock in river beds gives rise to cracks and voids that are likely to alter the incision rate of the material when subjected to impacts of moving sediment. In this study, flume experiments are performed to develop an understanding of how wet-dry cycling affects the rock tensile strength and the bedrock erosion rate. To represent the physical effects of weathering, boring cores taken from natural bedrock channel are exposed to artificial wet-dry cycles. The experimental results suggest the following: (1) the abrasion coefficient for fresh bedrock is estimated by β = 1.0 × 10− 4σT− 2(d/ksb)0.5, where σT is the tensile strength, d is the diameter of colliding gravel, and ksb is the hydraulic roughness height of bedrock; (2) the tensile strength of the bedrock decreases exponentially as a result of repeated wet-dry cycles, σT/σT0 = exp (-CTNWa0/σT0), where σT0 is the initial tensile strength, Wa0 is the initial normalized rate of water absorption., N is the number of wet-dry cycles, and CT is a constant; (3) the erosion rate of fresh bedrock depends on the inverse of the square of tensile strength, but the erosion rate of weathered bedrock depends on the − 1.5 power of tensile strength.

Local perturbations perturb—exponentially–locally

International Nuclear Information System (INIS)

De Roeck, W.; Schütz, M.

2015-01-01

We elaborate on the principle that for gapped quantum spin systems with local interaction, “local perturbations [in the Hamiltonian] perturb locally [the groundstate].” This principle was established by Bachmann et al. [Commun. Math. Phys. 309, 835–871 (2012)], relying on the “spectral flow technique” or “quasi-adiabatic continuation” [M. B. Hastings, Phys. Rev. B 69, 104431 (2004)] to obtain locality estimates with sub-exponential decay in the distance to the spatial support of the perturbation. We use ideas of Hamza et al. [J. Math. Phys. 50, 095213 (2009)] to obtain similarly a transformation between gapped eigenvectors and their perturbations that is local with exponential decay. This allows to improve locality bounds on the effect of perturbations on the low lying states in certain gapped models with a unique “bulk ground state” or “topological quantum order.” We also give some estimate on the exponential decay of correlations in models with impurities where some relevant correlations decay faster than one would naively infer from the global gap of the system, as one also expects in disordered systems with a localized groundstate

Implementation of soil protection objectives at local level - case study in eight municipalities; Maaperaensuojelun toteutuminen paikallistasolla. Tapaustutkimus kahdeksassa kunnassa

Energy Technology Data Exchange (ETDEWEB)

Lehtinen, H.

2000-06-01

This study aims to define the possibilities of the local administration to implement the objectives of soil protection. Important soil issues and development needs were analysed from eight group interviews and written material collected from the voluntarily participating municipalities. Relevant legislation was also reviewed as well as the experiences the municipalities included in the study, had about their action plans for the most important groundwater areas. The scope of a local soil protection policy and its objectives were manifested rather narrowly both in the group interviews and in the planning documents. Focus was on the quality of the groundwater resources and on a better control of the contamination risks. Most important soil problems appeared to be related to storage of oil and hazardous chemicals or accidents occurring in their transport, contaminated land areas, or sand and gravel extraction. Moreover the conflicts that arise in municipal decision-making concerning land use and physical planning were discussed in the interviews. Development needs were usually linked to physical planning at a general level, soil research and monitoring, clean-up of contaminated sites, diminishing of traffic contamination risks, and intensifying supervision, counselling and information dissemination. The interviewed groups saw a need to develop soil protection with greater awareness and more systematically than before, as an integral part of existing municipal administration and decision-making. Action plans for groundwater areas were experienced as useful tools to promote soil protection, but the need for other tools was also acknowledged. Stronger emphasise should be put on the economic and social viewpoints in sustainable development when assessing and monitoring further success in soil protection. Appropriate indicators are also needed. (orig.)

Groundwater monitoring of an open-pit limestone quarry: groundwater characteristics, evolution and their connections to rock slopes.

Science.gov (United States)

Eang, Khy Eam; Igarashi, Toshifumi; Fujinaga, Ryota; Kondo, Megumi; Tabelin, Carlito Baltazar

2018-03-06

Groundwater flow and its geochemical evolution in mines are important not only in the study of contaminant migration but also in the effective planning of excavation. The effects of groundwater on the stability of rock slopes and other mine constructions especially in limestone quarries are crucial because calcite, the major mineral component of limestone, is moderately soluble in water. In this study, evolution of groundwater in a limestone quarry located in Chichibu city was monitored to understand the geochemical processes occurring within the rock strata of the quarry and changes in the chemistry of groundwater, which suggests zones of deformations that may affect the stability of rock slopes. There are three distinct geological formations in the quarry: limestone layer, interbedded layer of limestone and slaty greenstone, and slaty greenstone layer as basement rock. Although the hydrochemical facies of all groundwater samples were Ca-HCO 3 type water, changes in the geochemical properties of groundwater from the three geological formations were observed. In particular, significant changes in the chemical properties of several groundwater samples along the interbedded layer were observed, which could be attributed to the mixing of groundwater from the limestone and slaty greenstone layers. On the rainy day, the concentrations of Ca 2+ and HCO 3 - in the groundwater fluctuated notably, and the groundwater flowing along the interbedded layer was dominated by groundwater from the limestone layer. These suggest that groundwater along the interbedded layer may affect the stability of rock slopes.

Local Foods, Local Places Summary Reports

Science.gov (United States)

These reports summarize community projects done with Local Foods, Local Places assistance, including farmers markets, cooperatives, community gardens, and other food-related enterprises that can boost local economies and drive revitalization.

Cost Effective, Ultra Sensitive Groundwater Monitoring for Site Remediation and Management

Science.gov (United States)

2015-05-01

evaporites, sandstone, gravel, conglomerate, and andesitic basalt . Closed basin; playa, alluvial fan, fluvial 600 to 10,000+ Unconfined, leaky...confined Lower unit Breccia, conglomerate, sandstone, siltstone, and local basaltic to rhyolitic flows and pyroclastic rocks. Alluvial fan, fluvial...with large volumes of groundwater. Three of the cartridges additionally protected by glass fiber filters (Acrodisc AP-4523; Pall GmbH, Dreieich, GE

Sulfur-aided phytoextraction of Cd and Zn by Salix smithiana combined with in situ metal immobilization by gravel sludge and red mud

International Nuclear Information System (INIS)

Iqbal, Muhammad; Puschenreiter, Markus; Oburger, Eva; Santner, Jakob; Wenzel, Walter W.

2012-01-01

As phytoextraction implementation may be limited by metal toxicity and leaching, we investigated the idea of in situ metal immobilization in bulk soil, while increasing metal bioavailability in the rhizosphere. Salix smithiana was grown in a pot experiment on two Cd/Zn polluted soils. Treatments with or without willows included: no additives; gravel sludge + red mud kg −1 ; acidification with S to pH 3.5; and metal immobilization combined with soil acidification. Salix smithiana removed up to 0.78 ± 0.06% total Cd and 0.34% (±0.02) total Zn from the non-treated soils. The phytoextraction efficiency in the S treatments was enhanced by up to ∼50% in response to metal solubility that was magnified by reductive co-dissolution from Mn (IV) and Fe(III) (oxy)hydroxides during microbial S oxidation in the willow rhizosphere. The proposed technique proved to enhance phytoextraction efficiency while controlling the risk of metal leaching from the root zone and phytotoxicity. - Highlights: ► Phytoextraction of Cd and Zn using willow (Salix smithiana) was enhanced by elemental sulfur. ► Reductive metals dissolution by microbial S oxidation was magnified in the willow rhizosphere. ► Thus metal bioavailability was high at the location of uptake in the phytoextraction crop. ► Concurrent immobilization by soil amendments can reduce metal leaching from the bulk soil. - Magnified Cd and Zn availability in S-amended rhizosphere of Salix smithiana enhances shoot Cd/Zn removal while metal leaching from the root zone can be reduced by immobilizing soil amendments.

Severnaya Zemlya, arctic Russia: a nucleation area for Kara Sea ice sheets during the Middle to Late Quaternary

DEFF Research Database (Denmark)

Möller, Per; Lubinski, David J.; Ingólfsson, Ólafur

2006-01-01

Quaternary glacial stratigraphy and relative sea-level changes reveal at least four expansions of the Kara Sea ice sheet over the Severnaya Zemlya Archipelago at 79°N in the Russian Arctic, as indicated from tills interbedded with marine sediments, exposed in stratigraphic superposition, and from......-5e and MIS 5d-3. The MIS 6-5e event, associated with the high marine limit, implies ice-sheet thickness of >2000 m only 200 km from the deep Arctic Ocean, consistent with published evidence of ice grounding at ~1000 m water depth in the central Arctic Ocean. Till fabrics and glacial tectonics record...... repeated expansions of local ice caps exclusively, suggesting wet-based ice cap advance followed by cold-based regional ice-sheet expansion. Local ice caps over highland sites along the perimeter of the shallow Kara Sea, including the Byrranga Mountains, appear to have repeatedly fostered initiation...

AM2 Brickwork Pattern Evaluation with Refurbished Matting

Science.gov (United States)

2015-08-01

from a local source in Vicksburg, MS, and was subjected to laboratory tests including grain-size analysis ( hydrometer ), Atterberg Limits, modified... HYDROMETER GRAIN SIZE IN MILLIMETERS 0.0010.010.1110100 50 5 0.5 0.05 0.005 4 3 2 1 3 4 6 8 10 14 16 20 30 40 50 70 100 140 20011/ 2 3 / 4 3 / 81/ 2 GRAVEL

Environmental Assessment of Proposed Mixed-Use Business Park on an Enchanced Use Lease at Grand Forks Air Force Base, North Dakota

Science.gov (United States)

2014-04-01

water from the local service providers; however, sanitary sewer services would be provided by GFAFB (Giltner 2013). Alternative 1 would include...utilizing the base include red-winged blackbird (Agelaius phoeniceus), mourning dove (Zenaida macroura), clay - colored sparrow (Spizella pallida), and...USAF 2006a). The glacial deposits are composed of silts, clays , sand, and gravel generally 225 ft thick, comprised of approximately 95 ft of clay

String-localized quantum fields and modular localization

Energy Technology Data Exchange (ETDEWEB)

Mund, J. [Juiz de Fora Univ., MG (Brazil). Dept. de Fisica; Schroer, B. [FU-Berlin, Berlin (Germany). Inst. fuer Theoretische Physik; Yngvason, J. [Erwin Schroedinger Institute for Mathematical Physics, Vienna (Austria)

2005-12-15

We study free, covariant, quantum (Bose) fields that are associated with irreducible representations of the Poincare group and localized in semi-infinite strings extending to spacelike infinity. Among these are fields that generate the irreducible representations of mass zero and infinite spin that are known to be incompatible with point-like localized fields. For the massive representation and the massless representations of finite helicity, all string-localized free fields can be written as an integral, along the string, of point-localized tensor or spinor fields. As a special case we discuss the string-localized vector fields associated with the point-like electromagnetic field and their relation to the axial gauge condition in the usual setting. (author)

String-localized quantum fields and modular localization

International Nuclear Information System (INIS)

Mund, J.

2005-12-01

We study free, covariant, quantum (Bose) fields that are associated with irreducible representations of the Poincare group and localized in semi-infinite strings extending to spacelike infinity. Among these are fields that generate the irreducible representations of mass zero and infinite spin that are known to be incompatible with point-like localized fields. For the massive representation and the massless representations of finite helicity, all string-localized free fields can be written as an integral, along the string, of point-localized tensor or spinor fields. As a special case we discuss the string-localized vector fields associated with the point-like electromagnetic field and their relation to the axial gauge condition in the usual setting. (author)

Paleocene-Eocene Sediments Interbedded With Volcanics Within the Lycian Nappes: Faralya Formation

Directory of Open Access Journals (Sweden)

Mustafa Şenel

1991-06-01

Full Text Available The presumably allochthonous structural units in the Southwestern Turkey between the Menderes massif and Beydağları autochthon are known as the Lycian nappes. Some of these units particularly beneath the ophiolite nappe end up with the Faralya formation of Paleocene-Lutetian age. The striking feature of this formation which includes micrite, clayey micrite, claystone, sandstone and conglomerate, is the presence of basic volcanite interbeds of Eocene age, This volcanite bearing formation exhibits a strong similarity to those of the other formations in Southwestern Turkey most of which include similar basic volcanites. Eocene basic volcanites are also known in the Akseki autochthon to the south of Seydişehir (Geyikdağ unit in broad sense. Similar extensive lateral movements (Eocene mountain building processes developed over the Faralya formation are seen over the volcanite bearing formations to the south of Menderes massif as well as to the north of Isparta angle and the Akseki autochthon. These features indicate that the area between the Menderes massif and Akseki autochthon (Geyikdağ unit reflects common basinal characters in terms of depositional conditions, volcanism and the traces of Eocene mountain building process.

Impact load-induced micro-structural damage and micro-structure associated mechanical response of concrete made with different surface roughness and porosity aggregates

International Nuclear Information System (INIS)

Erdem, Savaş; Dawson, Andrew Robert; Thom, Nicholas Howard

2012-01-01

The relationship between the nature of micro damage under impact loading and changes in mechanical behavior associated with different microstructures is studied for concretes made with two different coarse aggregates having significant differences mainly in roughness and porosity — sintered fly ash and uncrushed gravel. A range of techniques including X-ray diffraction, digital image analysis, mercury porosimetry, X-ray computed tomography, laser surface profilometry and scanning electron microscopy were used to characterize the aggregates and micro-structures. The concrete prepared with lightweight aggregates was stronger in compression than the gravel aggregate concrete due to enhanced hydration as a result of internal curing. In the lightweight concrete, it was deduced that an inhomogeneous micro-structure led to strain incompatibilities and consequent localized stress concentrations in the mix, leading to accelerated failure. The pore structure, compressibility, and surface texture of the aggregates are of paramount importance for the micro-cracking growth.

Inference for local autocorrelations in locally stationary models.

Science.gov (United States)

Zhao, Zhibiao

2015-04-01

For non-stationary processes, the time-varying correlation structure provides useful insights into the underlying model dynamics. We study estimation and inferences for local autocorrelation process in locally stationary time series. Our constructed simultaneous confidence band can be used to address important hypothesis testing problems, such as whether the local autocorrelation process is indeed time-varying and whether the local autocorrelation is zero. In particular, our result provides an important generalization of the R function acf() to locally stationary Gaussian processes. Simulation studies and two empirical applications are developed. For the global temperature series, we find that the local autocorrelations are time-varying and have a "V" shape during 1910-1960. For the S&P 500 index, we conclude that the returns satisfy the efficient-market hypothesis whereas the magnitudes of returns show significant local autocorrelations.

Local Stereo Matching Using Adaptive Local Segmentation

NARCIS (Netherlands)

Damjanovic, S.; van der Heijden, Ferdinand; Spreeuwers, Lieuwe Jan

We propose a new dense local stereo matching framework for gray-level images based on an adaptive local segmentation using a dynamic threshold. We define a new validity domain of the fronto-parallel assumption based on the local intensity variations in the 4-neighborhood of the matching pixel. The

Inverse Porosity-Hydraulic Conductivity Relationship in Sand-and-Gravel Aquifers Determined From Analysis of Geophysical Well Logs: Implications for Transport Processes

Science.gov (United States)

Morin, R. H.

2004-05-01

It is intuitive to think of hydraulic conductivity K as varying directly and monotonically with porosity P in porous media. However, laboratory studies and field observations have documented a possible inverse relationship between these two parameters in unconsolidated deposits under certain grain-size distributions and packing arrangements. This was confirmed at two sites in sand-and-gravel aquifers on Cape Cod, Massachusetts, where sets of geophysical well logs were used to examine the interdependence of several aquifer properties. Along with K and P, the resistivity R and the natural-gamma activity G of the surrounding sediments were measured as a function of depth. Qualitative examination of field results from the first site was useful in locating a contaminant plume and inferred an inverse relation between K and P; this was substantiated by a rigorous multivariate analysis of log data collected from the second site where K and P were determined to respond in a bipolar manner among the four independent variables. Along with this result come some implications regarding our conceptual understanding of contaminant transport processes in the shallow subsurface. According to Darcy's law, the interstitial fluid velocity V is proportional to the ratio K/P and, consequently, a general inverse K-P relationship implies that values of V can extend over a much wider range than conventionally assumed. This situation introduces a pronounced flow stratification within these granular deposits that can result in large values of longitudinal dispersivity; faster velocities occur in already fast zones and slower velocities in already slow zones. An inverse K-P relationship presents a new perspective on the physical processes associated with groundwater flow and transport. Although the results of this study apply strictly to the Cape Cod aquifers, they may merit a re-evaluation of modeling approaches undertaken at other locations having similar geologic environments.

Role of river flow and sediment mobilization in riparian alder establishment along a bedrock-gravel river, South Fork Eel River, California

Science.gov (United States)

Jablkowski, P.; Johnson, E. A.; Martin, Y. E.

2017-10-01

Climatic, hydraulics, hydrologic, and fluvial geomorphic processes are the main drivers of riparian white alder (Alnus rhombifolia Nutt.) distribution in northern California. The Mediterranean climate and canyon bound, bedrock-gravel morphology of the South Fork Eel have a distinct effect on these processes. White alder seeds are preferentially deposited on river bars where river hydraulics create eddies coinciding with the downstream part of riffles and the upstream part of pools. Seeds are generally deposited below bankfull elevations by the descending hydrograph during the spring season in this Mediterranean climate. For successful germination and establishment, the seeds must be deposited at a location such that they are not remobilized by late spring flows. The summer establishment period is defined from the date of seed deposition and germination to the fall/winter date of river sediment mobilization. Seedling root growth rate decreases exponentially with decreasing water potential. However, seedlings are shown not to be generally limited by water availability at the elevations they are most commonly deposited. The establishment of white alder seedlings following the first summer will therefore depend on their ability to resist fall/winter high flows. The method proposed here compares the predicted rooting depth to predicted sediment scour rates. The length of the establishment period rather than water availability determines final seedling rooting depth. Over the past 40 years, very few years had establishment periods that were long enough or had fast enough alder growth rates to survive winter floods that often scour deeper than the total root length. The low survival of seedlings in the first autumn season following germination is believed to be a principal reason for the missing age classes often found in alder distributions along rivers.

Local food:

DEFF Research Database (Denmark)

Sundbo, Donna Isabella Caroline

2013-01-01

are identified and then categorised according to whether they pertain to the food product itself or the production methods and facilities and whether they describe physical or social properties of local food. From this a model with four categories is developed. It is found that properties of the product are more......Recently there has been more focus on food in general and local food in particular. But what is local food? And what are the perceptions of this concept according to theory and to providers and consumers of local food? This article first summarises and compares three different theoretical...... perspectives on local food, namely experience economy, local food systems and what is termed pro-industrialism. These have differing and sometimes opposite conceptualisations and aims for the concept of local food. Using the perspective of experience economy as theoretical background, the concept of local food...

Microbial community variation and functions to excess sludge reduction in a novel gravel contact oxidation reactor

Energy Technology Data Exchange (ETDEWEB)

Lin Shanshan; Jin, Y.; Fu, L. [School of Urban and Environmental Science, Northeast Normal University, Changchun (China); Quan, C. [Jilin University, College of medicine, Changchun (China); Yang, Y.S., E-mail: yangy6@cf.ac.uk [Cardiff University, School of Earth and Ocean Sciences, Cardiff CF10 3YE (United Kingdom)

2009-06-15

Excess biomass produced within the degradation processes of organic pollutants is creating environmental challenges. The gravel contact oxidation reactor (GCOR) filled with crushed stone globular aggregates as carriers, has been demonstrated capable of reducing the excess sludge effectively in some pilot and small-scale engineering studies. In order to evaluate the variation and structure of the microbial community and their functions to excess sludge reduction in GCOR, a conventional activated sludge reactor (ASR) was studied as a comparison. The 16S rDNA library of the universal bacteria was constructed, Shannon's diversity index (H) and Species evenness (E) were calculated with distance-based operational taxonomic unit and richness (DOTUR) for microbial diversity. Real-time quantity PCR and optical microscope were used for absolute bacterial DNA concentration and eukarya identification, respectively. Meanwhile, the suspended solid index in GCOR and ASR was detected for assessing the excess sludge production. The results indicated that the most abundant bacteria in GCOR were those related to the {beta}-Proteobacteria group, then {gamma}-Proteobacteria and to Cytophaga-Flexibacter-Bacteriode (CFB). In the ASR samples major bacteria were in the closest match with {gamma}-Proteobacteria, then {beta}-Proteobacteria and CFB. Shannon's index (H) was higher (3.41) for diversity of bacteria extracted from the carrier samples in GCOR than that (2.71) from the sludge sample in ASR. Species evenness (E) for the isolates from GCOR and ASR samples was 0.97 and 0.96, respectively. Comparison of the universal bacteria population in GCOR and ASR shows that the total bacterial DNA concentration on the GCOR carriers were 8.98 x 10{sup 5} {mu}g/{mu}l, twice that in ASR of 4.67 x 10{sup 5} {mu}g/{mu}l under normal operation of two reactors. But the MLSS in GCOR was only 4.5 mg/L, 25 times less than that in ASR of 115.4 mg/L. The most representative eukarya were protozoa

Microbial community variation and functions to excess sludge reduction in a novel gravel contact oxidation reactor

International Nuclear Information System (INIS)

Lin Shanshan; Jin, Y.; Fu, L.; Quan, C.; Yang, Y.S.

2009-01-01

Excess biomass produced within the degradation processes of organic pollutants is creating environmental challenges. The gravel contact oxidation reactor (GCOR) filled with crushed stone globular aggregates as carriers, has been demonstrated capable of reducing the excess sludge effectively in some pilot and small-scale engineering studies. In order to evaluate the variation and structure of the microbial community and their functions to excess sludge reduction in GCOR, a conventional activated sludge reactor (ASR) was studied as a comparison. The 16S rDNA library of the universal bacteria was constructed, Shannon's diversity index (H) and Species evenness (E) were calculated with distance-based operational taxonomic unit and richness (DOTUR) for microbial diversity. Real-time quantity PCR and optical microscope were used for absolute bacterial DNA concentration and eukarya identification, respectively. Meanwhile, the suspended solid index in GCOR and ASR was detected for assessing the excess sludge production. The results indicated that the most abundant bacteria in GCOR were those related to the β-Proteobacteria group, then γ-Proteobacteria and to Cytophaga-Flexibacter-Bacteriode (CFB). In the ASR samples major bacteria were in the closest match with γ-Proteobacteria, then β-Proteobacteria and CFB. Shannon's index (H) was higher (3.41) for diversity of bacteria extracted from the carrier samples in GCOR than that (2.71) from the sludge sample in ASR. Species evenness (E) for the isolates from GCOR and ASR samples was 0.97 and 0.96, respectively. Comparison of the universal bacteria population in GCOR and ASR shows that the total bacterial DNA concentration on the GCOR carriers were 8.98 x 10 5 μg/μl, twice that in ASR of 4.67 x 10 5 μg/μl under normal operation of two reactors. But the MLSS in GCOR was only 4.5 mg/L, 25 times less than that in ASR of 115.4 mg/L. The most representative eukarya were protozoa both in GCOR (15 no. per 20 ml) and in ASR (15

Interactions between Channel Morphology and the Propagation of Coarse Sediment Augmentations Downstream from Dams

Science.gov (United States)

Gaeuman, D. A.; Dickenson, S.; Pyles, M.

2009-12-01

Gravel augmentations are being implemented in a number of streams where natural recruitment of gravel is impeded by dams. Uncertainties relevant to the management of gravel augmentations include the quantities of gravel needed to achieve habitat benefits at downstream locations and the temporal and spatial scales over which those benefits that will be realized. The solution to such questions depends to a large extent on how gravel slugs evolve as the material is transported downstream, i.e., whether the gravel translates downstream as a coherent wave or whether it tends to disperse. A number of recent studies conducted in laboratory flumes or by numerical simulation that gravels slugs tend to disperse rather than translate. However, these studies do not consider the influence of channel morphology on slug behavior. Initial monitoring results based from 2 California streams suggest that natural channel morphology suppresses slug dispersion because the gravel tends to accumulate in discrete deposition zones. Field mapping and about 200 tracer stones implanted with passive integrated transponder (PIT) tags show that gravel recruitment piles of about 80 tons each placed in Grass Valley Creek in 2007 and 2008 were deposited as 2 new bars immediately downstream. The more upstream of the 2 bars formed during the 2007 winter and spring flood season, whereas the more downstream bar did not appear until the following year. A sharp deposition front and an absence of tracers in the reaches downstream strongly suggest that none of the added gravel was transported downstream beyond the area of bar formation in either year. A relatively small proportion of the mobilized tracer particles (59%) were located following the 2007 flood season, probably due to deep burial in the newly deposited bar and to radio interference caused by the high concentration of tracers in a small area. The proportion of newly introduced or previously-located tracers that were relocated in 2009 was

K-Ar Geochronology and isotopic composition of the late oligocene- early miocene Ancud volcanic complex, Chiloe

International Nuclear Information System (INIS)

Munoz B, Jorge; Duhart O, Paul; Farmer, G. Lang; Stern, Charles R

2001-01-01

The Ancud Volcanic Complex (Gally and Sanchez , 1960) forms a portion of the Mid-Tertiary Coastal Magmatic Belt which outcrops in the area of northern Chiloe island. Main exposures occur at Ancud, Punta Polocue, Punihuil, Pumillahue, Tetas de Teguaco and Bahia Cocotue. The Ancud Volcanic Complex consists of basaltic to basaltic andesites lava flows and volcanic necks and rhyolitic pyroclastic flows and vitric domes. Previous studies indicate a Late Oligocene-Early Miocene age (Garcia et al., 1988; Stern and Vergara, 1992; Munoz et al., 2000). The Ancud Volcanic Complex covers and intrudes Palaeozoic-Triassic metamorphic rocks and is partially covered by an early to middle Miocene marine sedimentary sequence known as Lacui Formation (Valenzuela, 1982) and by Pleistocene glacial deposits (Heusser, 1990). At Punihuil locality, lava flows are interbedded with the lower part of the marine sedimentary sequence, which includes significant amounts of redeposited pyroclastic components. Locally, the presence of hyaloclastic breccias suggests interaction of magma with marine water (au)

Hydrochemistry of the Mahomet Bedrock Valley Aquifer, East-Central Illinois: indicators of recharge and ground-water flow

Science.gov (United States)

Panno, S.V.; Hackley, Keith C.; Cartwright, K.; Liu, Chao-Li

1994-01-01

A conceptual model of the ground-water flow and recharge to the Mahomet Bedrock Valley Aquifer (MVA), east-central Illinois, was developed using major ion chemistry and isotope geochemistry. The MVA is a 'basal' fill in the east-west trending buried bedrock valley composed of clean, permeable sand and gravel to thicknesses of up to 61 m. It is covered by a thick sequence of glacial till containing thinner bodies of interbedded sand and gravel. Ground water from the MVA was found to be characterized by clearly defined geochemical regions with three distinct ground-water types. A fourth ground-water type was found at the confluence of the MVA and the Mackinaw Bedrock Valley Aquifer (MAK) to the west. Ground water in the Onarga Valley, a northeastern tributary of the MVA, is of two types, a mixed cation-SO42- type and a mixed cation-HCO3- type. The ground water is enriched in Na+, Ca2+, Mg2+, and SO42- which appears to be the result of an upward hydraulic gradient and interaction of deeper ground water with oxidized pyritic coals and shale. We suggest that recharge to the Onarga Valley and overlying aquifers is 100% from bedrock (leakage) and lateral flow from the MVA to the south. The central MVA (south of the Onarga Valley) is composed of relatively dilute ground water of a mixed cation-HCO3- type, with low total dissolved solids, and very low concentrations of Cl- and SO42-. Stratigraphic relationships of overlying aquifers and ground-water chemistry of these and the MVA suggest recharge to this region of the MVA (predominantly in Champaign County) is relatively rapid and primarily from the surface. Midway along the westerly flow path of the MVA (western MVA), ground water is a mixed cation-HCO3- type with relatively high Cl-, where Cl- increases abruptly by one to ??? two orders of magnitude. Data suggest that the increase in Cl- is the result of leakage of saline ground water from bedrock into the MVA. Mass-balance calculations indicate that approximately 9.5% of

Study on weathering index for improving the reliability of terrace correlation and chronology. Based on the observation and analysis of terrace deposit distributed in the Mid Niigata region and others

International Nuclear Information System (INIS)

Hamada, Takaomi; Hataya, Ryuta

2009-01-01

We carried out field survey and laboratory analysis to investigate various weathering indexes in loam and terrace deposit at outcrops of the terraces distributed in Mid-Niigata area and other two areas, which were correlated and chronologized accurately. We also collect and analyze the data of color and hardness of eolian loam, matrix of terrace deposit, thickness of decolorated and/or browning rim of terrace gravels, color and roughness of gravel surface and effective porosity on each terrace. According to result of the analysis, thickness of weathering rind can be an useful index for terrace correlation. Weathering rind is observed frequently in mafic and fine gravels, as a result of statistical survey of occurrence of the patterns of weathering type. According to the result of our field survey, Middle terrace contains few decayed gravels and Higher terrace group, which is older than MIS8 terrace, contains large amounts of decayed gravels. We can distinguish two different age terraces according to ratio of decayed gravel concentration in terrace deposit. Combination of data of thickness of weathering rind of gravel and concentration of decayed gravel in terrace deposit, adequate terrace correlation can be obtained with increased reliability. Difference of weathering degree can be detected by a combination of several indexes that can be observed in outcrops, it is possible to distinguish between different age terraces. Color and hardness of loam, thickness of weathering rind of terrace gravel can be indexes of weathering, these can explain the facts observed in outcrops. (author)

Contingency table analysis of pebble lithology and roundness: A case study of Huangshui River, China and comparison to rivers in the Rocky Mountains, USA

Science.gov (United States)

Miao, X.; Lindsey, D.A.; Lai, Z.; Liu, Xiuying

2010-01-01

Contingency table analysis of pebble lithology and roundness is an effective way to identify the source terrane of a drainage basin and to distinguish changes in basin size, piracy, tectonism, and other events. First, the analysis to terrace gravel deposited by the Huangshui River, northeastern Tibet Plateau, China, shows statistically contrasting pebble populations for the oldest terrace (T7, Dadongling, 1.2. Ma) and the youngest terraces (T0-T3, ?. 0.15. Ma). Two fluvial processes are considered to explain the contrast in correlation between lithology and roundness in T7 gravel versus T0-T3 gravel: 1) reworking of T7 gravel into T0-T3 gravel and 2) growth in the size of the river basin between T7 and T0-T3 times. We favor growth in basin size as the dominant process, from comparison of pebble counts and contingency tables. Second, comparison of results from Huangshui River of China to three piedmont streams of the Rocky Mountains, USA highlights major differences in source terrane and history. Like Rocky Mountain piedmont gravel from Colorado examples, the Huangshui gravels show a preference (observed versus expected frequency) for rounded granite. But unlike Rocky Mountain gravel, Huangshui gravel shows a preference for angular quartzite and for rounded sandstone. In conclusion, contrasting behavior of lithologies during transport, not always apparent in raw pebble counts, is readily analyzed using contingency tables to identify the provenance of individual lithologies, including recycled clasts. Results of the analysis may help unravel river history, including changes in basin size and lithology. ?? 2009.

Effects of ageing on the hydraulics of water wells and the influence of non-Darcy flow

Science.gov (United States)

Houben, Georg J.; Wachenhausen, Julia; Guevara Morel, Carlos R.

2018-04-01

Well ageing is mostly caused by mechanical and biogeochemical clogging processes, which affect the gravel pack, screen slots and casing. Clogging deposits increase head losses due to a constriction of the hydraulically effective area. For this study, clogging is mimicked by systematically reducing the gravel pack porosity, the screen open area and the nominal inner casing diameter. Groundwater flow velocity strongly increases close to the well, inducing inertial and turbulent flow components. Therefore, gravel pack head losses were calculated using the Forchheimer-Engelund equation, in conjunction with the Kozeny-Carman equation, which relates gravel pack porosity and hydraulic conductivity. Screen losses were assessed using the Orifice equation and turbulent casing losses with the Darcy-Weisbach equation. For the settings chosen here, a dramatic increase of head losses occurs when the clogging has reduced the effective porosity in the gravel pack by 65%, the open area of the screen by ≥98%, and the casing diameter by 50%. Since the latter two conditions are rarely reached in actual wells, the clogging of the gravel pack is the decisive parameter that controls well ageing. Regular monitoring of the well yield is therefore needed, since processes in the gravel pack are difficult to track directly. Unlike the deposits on the casing and in the screen slots, obstructions in the gravel pack are much more difficult to remove.

New Communication Technologies, Local Journalism and the Perception of Locality

Directory of Open Access Journals (Sweden)

Ali ÖZCAN

2016-12-01

Full Text Available Studies on local journalism as an important element of participatory democracy generally focus on the history of the local press, the financial insufficiencies of local newspapers as well as technical/ technological incompetency that occurs as a result of these factors. This research analyzes local newspapers with a new scientific point of view by focusing on the perception of locality as a mental projection of geographical constraint. Perspectives regarding the transformations on perceptions of locality as a result of the disappearance of time and space constraints due to new communication technologies, and the opportunities that new communication environments offer to local newspapers will be provided. Moreover, the ways in which local newspapers reflect on locality with their printed versions under time and space constraints will be analyzed. The research scope of the study has been limited to 15 newspapers in Konya. Structured interviews and content analysis methods were used for data collection and analysis.

Kootenai Canyon Archaeology. The 1979 LAURD (Libby Additional Units and Reregulating Dam) Project.

Science.gov (United States)

1982-01-01

of the writing of this descriptive report fell to him. Marilyn Bailey was assistant laboratory director for the duration, her persistence and... writing the final reports. The field effort involved an archaeological team that averaged about 42 people (26 field, 9 laboratory, 3 administrative, and 2...been derived from ielting icebergs. It is also possible that the poorly sorted gravels are a result of mass wasting. In either case a localized ice

New insight on the water management in Ica Valley-Peru

Science.gov (United States)

Guttman, Joseph; Berger, Diego

2014-05-01

The Andes divide Peru into three natural drainage basins: Pacific basin, Atlantic basin and Lake Titicaca basin. According to the National Water Authority (ANA), the Pacific basin is the driest basin. The bulk of water that feed the local aquifers in the coastal Pacific region is coming from rivers that flow west from the Andes. One of them is the Ica River- source of the Ica Aquifer and the Pampas de Villacuri Aquifer. The Ica River flows in a graben that was created by a series of faults. The graben is filled with sand and gravel with interbeded and lenses of clay. The aquifer thickness varies between 25 meters to more than 200 meters. The Ica Valley has an extension of 7700 km2 and belongs to the Province of Ica, the second larger economic center in Peru. The Valley is located in the hyperarid region of the Southern Coastal area of Peru with a few millimeters of precipitation per year. The direct recharge is almost zero. The recharge into the Ica Valley aquifer is comes indirectly by infiltration of storm water through the riverbed generates in the Andes, through irrigation canals and by irrigation return flow. In this hyperarid region, local aquifers like the Ica Valley are extremely valuable resources to local populations and are the key sources of groundwater for agriculture and population needs. Therefore, these aquifers play a crucial role in providing people with water and intense attention should be given to manage the water sector properly and to keep the aquifer sustainable for future generations. The total pumping (from rough estimations) is much greater than the direct and indirect recharge. The deficit in the water balance is reflected in large water level decline, out of operation of shallow wells and the ascending of saline water from deeper layers. The change from flood irrigation that contributes about 35-40% of the water to the aquifer, to drip irrigation dramatically reduces the amount of water that infiltrates into the sub-surface from the

Local Content

CSIR Research Space (South Africa)

Gibberd, Jeremy

2016-10-01

Full Text Available Local content refers to materials and products made in a country as opposed those that are imported. There is an increasing interest in the concept of local content as a means of supporting local economies and providing jobs (Belderbos & Sleuwaegen...

Catchment source contributions to the sediment-bound organic matter degrading salmonid spawning gravels in a lowland river, southern England

Energy Technology Data Exchange (ETDEWEB)

Collins, A.L., E-mail: adrian.collins@adas.co.uk [ADAS, Pendeford House, Wobaston Road, Wolverhampton WV9 5AP (United Kingdom); Geography and Environment, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); Williams, L.J.; Zhang, Y.S. [ADAS, Pendeford House, Wobaston Road, Wolverhampton WV9 5AP (United Kingdom); Marius, M. [Civil Engineering and Environment, University of Southampton, Highfield, Southampton S017 1BJ (United Kingdom); Dungait, J.A.J. [Department of Sustainable Systems and Grassland Science, Rothamsted Research—North Wyke, Okehampton, Devon EX20 2SB (United Kingdom); Smallman, D.J. [Civil Engineering and Environment, University of Southampton, Highfield, Southampton S017 1BJ (United Kingdom); Dixon, E.R. [Department of Sustainable Systems and Grassland Science, Rothamsted Research—North Wyke, Okehampton, Devon EX20 2SB (United Kingdom); Stringfellow, A. [Civil Engineering and Environment, University of Southampton, Highfield, Southampton S017 1BJ (United Kingdom); Sear, D.A. [Geography and Environment, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); Jones, J.I. [School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS (United Kingdom); Naden, P.S. [CEH Wallingford, Maclean Building, Benson Lane, Crowmarsh Gifford, Wallingford, Oxfordshire, OX10 8BB (United Kingdom)

2013-07-01

and can be applied alongside apportionment for the minerogenic component of fine-grained sediment ingressing the benthos. The findings suggest that human septic waste contributes to the interstitial fines ingressing salmonid spawning habitat in the study area. - Highlights: • Stable carbon and nitrogen isotopes and NIR reflectance spectra used as fingerprints • Results suggest human septic waste contributes to organic matter in spawning gravels. • Source contributions are: instream decaying vegetation > road verges > septic tanks > farm manures.

Rock on!

Science.gov (United States)

Clary, Renee; Wandersee, James

2012-01-01

Gravel is a component of parking lots, highway shoulders, garden pathways, and filtration systems. Few people bother to scientifically examine gravel and determine its origin, but gravel can be an effective, inexpensive, and abundant resource for science classrooms. It can serve as a portal for several interdisciplinary science activities and…

Geological and Oceanographic Perspectives on Event Bed Formation during Hurricane Katrina

National Research Council Canada - National Science Library

Keen, T. R; Furukawa, Y; Bentley, S. J; Slingerland, R. L; Teague, W. J; Dykes, J. D; Rowley, C. D

2006-01-01

Storm deposits in ancient shelf sediments typically form thick sequences of interbedded sand and mud deposited during shoreline regression, whereas modern shelf sediments are generally thin veneers...

Locally analytic vectors in representations of locally

CERN Document Server

Emerton, Matthew J

2017-01-01

The goal of this memoir is to provide the foundations for the locally analytic representation theory that is required in three of the author's other papers on this topic. In the course of writing those papers the author found it useful to adopt a particular point of view on locally analytic representation theory: namely, regarding a locally analytic representation as being the inductive limit of its subspaces of analytic vectors (of various "radii of analyticity"). The author uses the analysis of these subspaces as one of the basic tools in his study of such representations. Thus in this memoir he presents a development of locally analytic representation theory built around this point of view. The author has made a deliberate effort to keep the exposition reasonably self-contained and hopes that this will be of some benefit to the reader.

Special Foundation by means of reinforced-concrete caisson in Valencia Port; Cimentaciones especiales de los cajones del Muello Este. Puerto de Valencia

Energy Technology Data Exchange (ETDEWEB)

Gama Costa, P. M.

2010-07-01

This paper describes the process to construct a foundation by means of reinforced-concrete caisson on breakwaters. the project required to develop minimal dredging solutions as well as to improve the foundation areas of the what caissons. The improvement technique applied to the foundation area was based on gravel columns, since this solution was the most suitable for areas with high fine fraction contents, as it was the case. Gravel columns were executed following a bottom-feed method, and two different techniques: gravel tank top-feeding and gravel pumping. (Author)

Determining timing of Alaska Range exhumation and glaciation through cosmogenic nuclide burial dating.

Science.gov (United States)

Sortor, R. N.; Goehring, B. M.; Bemis, S. P.; Ruleman, C.; Nichols, K. A.; Ward, D. J.; Frothingham, M.

2017-12-01

The Alaska Range is a transpressional orogen with modern exhumation initiating 6 Ma. The stratigraphic record of unroofing and uplift of the foreland basin is largely preserved along the northern flank of the Alaska Range in the Pliocene-Pleistocene aged Nenana Gravel, an extensive alluvial fan and braidplain deposit. Chronometric control on the Nenana Gravel is largely lacking, with the limited available age control based on a single Ar-Ar tephra date in an underlying unit and via stratigraphic inferences for the upper portions. Higher-resolution dating of the Nenana Gravel unit is imperative in order to quantify deposition rates and the timing of uplift and deformation of the foreland basin. Furthermore, a glacial unit has been found to lie unconformably on top of the unit at Suntrana Creek and may represent the initiation of glacial advances in the Alaska Range. We present a suite of 26Al/10Be cosmogenic nuclide burial ages collected from the lower, middle, and upper sections of the Nenana Gravel at Suntrana Creek, as well as the overlying glacial unit. Three samples from the lower Nenana Gravel yield an isochron burial age of 4.42+0.67/-0.13 Ma, which represents initiation of Nenana Gravel deposition and may equate to early unroofing of the Alaska Range. Two samples collected from the middle of the Nenana Gravel unit produced an average simple burial age of 2.25+/-0.45 Ma, with a single sample stratigraphically above dating to 0.99 +/-1.60. Two samples from the upper-most portion of the Nenana Gravel yielded an average simple burial age of 1.27+/-0.22 Ma, and one sample from the glacial unit overlying the Nenana Gravel was dated to 0.97+/-0.06 Ma, representing one of the earliest glacial advances in the region. In addition, the age of the glacial unit provides a minimum age for inception of foreland basin uplift and abandonment of the Nenana Gravel in this region.

A morphing strategy to couple non-local to local continuum mechanics

KAUST Repository

Lubineau, Gilles

2012-06-01

A method for coupling non-local continuum models with long-range central forces to local continuum models is proposed. First, a single unified model that encompasses both local and non-local continuum representations is introduced. This model can be purely non-local, purely local or a hybrid depending on the constitutive parameters. Then, the coupling between the non-local and local descriptions is performed through a transition (morphing) affecting only the constitutive parameters. An important feature is the definition of the morphing functions, which relies on energy equivalence. This approach is useful in large-scale modeling of materials that exhibit strong non-local effects. The computational cost can be reduced while maintaining a reasonable level of accuracy. Efficiency, robustness and basic properties of the approach are discussed using one- and two-dimensional examples. © 2012 Elsevier Ltd.

A morphing strategy to couple non-local to local continuum mechanics

KAUST Repository

Lubineau, Gilles; Azdoud, Yan; Han, Fei; Rey, Christian C.; Askari, Abe H.

2012-01-01

A method for coupling non-local continuum models with long-range central forces to local continuum models is proposed. First, a single unified model that encompasses both local and non-local continuum representations is introduced. This model can be purely non-local, purely local or a hybrid depending on the constitutive parameters. Then, the coupling between the non-local and local descriptions is performed through a transition (morphing) affecting only the constitutive parameters. An important feature is the definition of the morphing functions, which relies on energy equivalence. This approach is useful in large-scale modeling of materials that exhibit strong non-local effects. The computational cost can be reduced while maintaining a reasonable level of accuracy. Efficiency, robustness and basic properties of the approach are discussed using one- and two-dimensional examples. © 2012 Elsevier Ltd.

Non-local charges in local quantum field theory

International Nuclear Information System (INIS)

Buchholz, D.; Lopuszanski, J.T.; Rabsztyn, S.

1985-05-01

Non-local charges are studied in the general setting of local quantum field theory. It is shown, that these charges can be represented as polynomials in the incoming respectively outgoing fields with coefficients (kernels) which are subject to specific constraints. For the restricted class of models of a scalar, massive, self interacting particle in four dimensions, a more detailed analysis shows that all non-local charges of the generic type (genus 2) are products of generators of the Poincare group. This analysis, which is based on the macroscopic causality properties of the S-matrix, seems to indicate that less trivial examples of non-local charges can only exist in two dimensions. (orig.)

Efficient Topological Localization Using Global and Local Feature Matching

Directory of Open Access Journals (Sweden)

Junqiu Wang

2013-03-01

Full Text Available We present an efficient vision-based global topological localization approach in which different image features are used in a coarse-to-fine matching framework. Orientation Adjacency Coherence Histogram (OACH, a novel image feature, is proposed to improve the coarse localization. The coarse localization results are taken as inputs for the fine localization which is carried out by matching Harris-Laplace interest points characterized by the SIFT descriptor. The computation of OACHs and interest points is efficient due to the fact that these features are computed in an integrated process. The matching of local features is improved by using approximate nearest neighbor searching technique. We have implemented and tested the localization system in real environments. The experimental results demonstrate that our approach is efficient and reliable in both indoor and outdoor environments. This work has also been compared with previous works. The comparison results show that our approach has better performance with higher correct ratio and lower computational complexity.

Local duality for 2-dimensional local ring

Indian Academy of Sciences (India)

dimensional complete local ring whose residue field is an n-dimensional local field in the sense of. Kato–Parshin. Our results generalize the Saito works in the case n = 0 and are applied to study the Bloch–Ogus complex for such rings in various cases.

Rapid ecological assessment of benthic indicators of water quality: a successful capacity-building experience for Brazilian postgraduate students in ecology

Directory of Open Access Journals (Sweden)

M. Callisto

Full Text Available Rapid Ecological Assessment protocols are important tools for the training of postgraduate students, as well as the collection of data on poorly-known and protected areas with the potential for the preservation of water supplies for urban areas. The objective of this study was to perform a survey of water quality and diversity of benthic macroinvertebrates in two sub-basins at the Mata do Junco Wildlife Refuge in the Brazilian state of Sergipe. The collection of data in the field, laboratory processing, and the interpretation and discussion of data were conducted in groups by students from two postgraduate programmes in Ecology and Conservation (UFMG and UFS, personnel of the state environment agency (SEMARH, school teachers from the local town of Capela, and members of the reserve's voluntary fire brigade. The results of the assessment were organised, analysed, and presented at the reserve headquarters in the form of posters, for the development of environmental education activities with pupils from local schools, as well as contributing to a SEMARH seminar. Samples were characterised by distinct taxonomic compositions and diversity, as confirmed by MDS and additive partitioning of diversity analyses. The gravel substrate presented the lower mean taxonomic richness in each sampling unit (a1 = 28%, while the average difference among samples (b1 diversity was elevated for both substrates (39% for leaf litter, 41% for gravel, reflecting the pronounced variation among samples, even adjacent ones within the same stream. Diversity between streams was lower in the case of leaf litter in comparison with gravel (b2 = 21 and 31%, respectively. A total of 57 fish specimens were collected with a predominance of individuals of the orders Characiformes (62% and Perciformes (21%. This rapid ecological assessment confirmed the importance of the conservation unit and emphasised the need for its continuation, given its importance for the maintenance of water

Natural resources management by local associations in Ifedore local ...

African Journals Online (AJOL)

Management of natural resource by local associations not only in its socio ecological but also in its socio economic context will go a long way in reducing environmental degradation in some local communities. This study examined the operational capacity for natural resource management by local associations in Ifedore ...

The geology and chronology of the Acheulean deposits in the Mieso area (East-Central Ethiopia).

Science.gov (United States)

Benito-Calvo, Alfonso; Barfod, Dan N; McHenry, Lindsay J; de la Torre, Ignacio

2014-11-01

This paper presents the Quaternary sequence of the Mieso area of Central-East Ethiopia, located in the piedmont between the SE Ethiopian Escarpment and the Main Ethiopian Rift-Afar Rift transition sector.In this region, a piedmont alluvial plain is terraced at þ25 m above the two main fluvial courses, the Mieso and Yabdo Rivers. The piedmont sedimentary sequence is divided into three stratigraphic units separated by unconformities. Mieso Units I and II contain late Acheulean assemblages and a weakly consolidated alluvial sequence, consisting mainly of fine sediments with buried soils and, to a lesser degree, conglomerates. Palaeo-wetland areas were common in the alluvial plain, represented by patches of tufas, stromatolites and clays. At present, the piedmont alluvial surface is preserved mainly on a dark brown soil formed at the top of Unit II. Unit III corresponds to a fluvial deposit overlying Unit II, and is defined by sands, silty clays and gravels, including several Later Stone Age (LSA) occurrences. Three fine-grained tephra levels are interbedded in Unit I (tuffs TBI and TA) and II (tuff CB), and are usually spatially-constrained and reworked. Argon/argon (40Ar/39Ar) dating from tuff TA, an ash deposit preserved in a palustrine environment, yielded an age of 0.212 ± 0.016 Ma (millions of years ago). This date places thetop of Unit I in the late Middle Pleistocene, with Acheulean sites below and above tuff TA. Regional correlations tentatively place the base of Unit I around the Early-Middle Pleistocene boundary, Unit II inthe late Middle Pleistocene and within the Late Pleistocene, and the LSA occurrences of Unit III in the LatePleistoceneeHolocene.

Microbial community stratification controlled by the subseafloor fluid flow and geothermal gradient at the Iheya North hydrothermal field in the Mid-Okinawa Trough (Integrated Ocean Drilling Program Expedition 331).

Science.gov (United States)

Yanagawa, Katsunori; Breuker, Anja; Schippers, Axel; Nishizawa, Manabu; Ijiri, Akira; Hirai, Miho; Takaki, Yoshihiro; Sunamura, Michinari; Urabe, Tetsuro; Nunoura, Takuro; Takai, Ken

2014-10-01

The impacts of lithologic structure and geothermal gradient on subseafloor microbial communities were investigated at a marginal site of the Iheya North hydrothermal field in the Mid-Okinawa Trough. Subsurface marine sediments composed of hemipelagic muds and volcaniclastic deposits were recovered through a depth of 151 m below the seafloor at site C0017 during Integrated Ocean Drilling Program Expedition 331. Microbial communities inferred from 16S rRNA gene clone sequencing in low-temperature hemipelagic sediments were mainly composed of members of the Chloroflexi and deep-sea archaeal group. In contrast, 16S rRNA gene sequences of marine group I Thaumarchaeota dominated the microbial phylotype communities in the coarse-grained pumiceous gravels interbedded between the hemipelagic sediments. Based on the physical properties of sediments such as temperature and permeability, the porewater chemistry, and the microbial phylotype compositions, the shift in the physical properties of the sediments is suggested to induce a potential subseafloor recharging flow of oxygenated seawater in the permeable zone, leading to the generation of variable chemical environments and microbial communities in the subseafloor habitats. In addition, the deepest section of sediments under high-temperature conditions (∼90°C) harbored the sequences of an uncultivated archaeal lineage of hot water crenarchaeotic group IV that may be associated with the high-temperature hydrothermal fluid flow. These results indicate that the subseafloor microbial community compositions and functions at the marginal site of the hydrothermal field are highly affected by the complex fluid flow structure, such as recharging seawater and underlying hydrothermal fluids, coupled with the lithologic transition of sediments. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

local

Directory of Open Access Journals (Sweden)

Abílio Amiguinho

2005-01-01

Full Text Available The process of socio-educational territorialisation in rural contexts is the topic of this text. The theme corresponds to a challenge to address it having as main axis of discussion either the problem of social exclusion or that of local development. The reasons to locate the discussion in this last field of analysis are discussed in the first part of the text. Theoretical and political reasons are there articulated because the question is about projects whose intentions and practices call for the political both in the theoretical debate and in the choices that anticipate intervention. From research conducted for several years, I use contributions that aim at discuss and enlighten how school can be a potential locus of local development. Its identification and recognition as local institution (either because of those that work and live in it or because of those that act in the surrounding context are crucial steps to progressively constitute school as a partner for development. The promotion of the local values and roots, the reconstruction of socio-personal and local identities, the production of sociabilities and the equation and solution of shared problems were the dimensions of a socio-educative intervention, markedly globalising. This scenario, as it is argued, was also, intentionally, one of transformation and of deliberate change of school and of the administration of the educative territoires.

Local Agenda 21 - from global idea to local action

DEFF Research Database (Denmark)

Hoffmann, Birgitte

1999-01-01

The article give a status of the Danish works with Local Agenda 21 and discusses Local Agenda 21 as a planning tool. It describes the idea of Local Agenda 21 as a large meeting, which everybody attends. This picture is elaborated and discussed form different angles: the items on the agenda...

Perspective sources of industrial minerals for building industry in Novohrad (Southern Slovakia

Directory of Open Access Journals (Sweden)

Beláček Boris

1999-03-01

Full Text Available Novohrad a region of Southern Slovakia has wealthy industrial history, which was built mostly on local natural raw materials. Some deposits are exhausted, but other are ready to be exploited. Among such industrial minerals are raw materials for building industry. There are industrial minerals for fine and rough ceramics, stones for building and pavement, sand and gravel. The perspective areas are listed on Tab. 1 - 6 and are shown on Fig 1 - 3.

Geohydrology of the Winchester Subbasin, Riverside County, California

Science.gov (United States)

Kaehler, Charles A.; Burton, Carmen A.; Rees, Terry F.; Christensen, Allen H.

1998-01-01

The 20-square-mile Winchester structural subbasin is an alluvium-filled paleocanyon that is as much as 900 feet deep. The alluvial aquifer is composed of detrital material that generally ranges in size from clay to fine gravel; the fine and coarse materials are mixed in some places and inter- bedded in others. The apparent lenticularity of fine- and coarse-grained materials and differing water quality with depth indicate that the aquifer is partly or locally confined.

Localized superconductors

International Nuclear Information System (INIS)

Ma, M.; Lee, P.A.

1985-01-01

We study the effects of Anderson localization on superconductivity by using a Bardeen-Cooper-Schrieffer (BCS)-type trial wave function which pairs electrons in exact time-reversed eigenstates of the single-particle Hamiltonian. Within this approximation, and neglecting localization effects on the effective Coulomb repulsion and the electron-phonon coupling, we find that superconductivity persists below the mobility edge. In fact, Anderson's theorem is valid in the localized phase as long as rhoΔ 0 L/sup d/ > 1 (rho is the density of states averaged over +- Δ 0 of the Fermi energy, Δ 0 the BCS gap parameter, and L the localization length). Hence the gap order parameter Δ(r) remains uniform in space at the BCS value Δ 0 . The superfluid density and response to electromagnetic perturbations, however, show marked differences from the ''dirty superconductor'' regime. For rhoΔ 0 L/sup d/ < 1, Δ(r) fluctuates spatially and eventually drops to zero. In the limit when states are site localized, the system crosses over into the ''Anderson negative-U glass.'' Considerations beyond the trial wave-function approximation will speed up the destruction of superconductivity. The superconductor formed from localized states has the property that its quasiparticle excitations are also localized. Such excitations can be probed by observing the normal current in a tunneling junction

Control of Eolian soil erosion from waste site surface barriers

International Nuclear Information System (INIS)

Ligotke, M.W.

1994-11-01

Physical models were tested in a wind tunnel to determine optimum surface-ravel admixtures for protecting silt-loam soil from erosion by, wind and saltating, sand stresses. The tests were performed to support the development of a natural-material surface barrier for and waste sites. Plans call for a 2-m deep silt-loam soil reservoir to retain infiltrating water from rainfall and snowmelt. The objective of the study was to develop a gravel admixture that would produce an erosion-resistant surface layer during, periods of extended dry climatic stress. Thus, tests were performed using simulated surfaces representing dry, unvegetated conditions present just after construction, after a wildfire, or during an extended drought. Surfaces were prepared using silt-loam soil mixed with various grades of sand and Travel. Wind-induced surface shear stresses were controlled over the test surfaces, as were saltating, sand mass flow rates and intensities. Tests were performed at wind speeds that approximated and exceeded local 100-year peak gust intensities. Surface armors produced by pea gravel admixtures were shown to provide the best protection from wind and saltating sand stresses. Compared with unprotected silt-loam surfaces, armored surfaces reduced erosion rates by more than 96%. Based in part on wind tunnel results, a pea gravel admixture of 15% will be added to the top 1 in of soil in a prototype barrier under construction in 1994. Field tests are planned at the prototype site to provide data for comparison with wind tunnel results

New model. Local financing for local energy

International Nuclear Information System (INIS)

Detroy, Florent

2015-01-01

While evoking the case of the VMH Energies company in the Poitou-Charentes region, and indicating the difference between France and Germany in terms of wind and photovoltaic energy production potential, of number of existing local companies, and of citizen-based funding, this article shows that renewable energies could put the energy production financing in France into question again, with a more important participation of local communities and of their inhabitants. The author describes how the law on energy transition makes this possible, notably with the strengthening of citizen participation. The author evokes some French local experiments and the case of Germany where this participation is already very much developed

Defining local food

DEFF Research Database (Denmark)

Eriksen, Safania Normann

2013-01-01

Despite evolving local food research, there is no consistent definition of “local food.” Various understandings are utilized, which have resulted in a diverse landscape of meaning. The main purpose of this paper is to examine how researchers within the local food systems literature define local...... food, and how these definitions can be used as a starting point to identify a new taxonomy of local food based on three domains of proximity....

Local/regional policies: Acting globally by thinking locally

International Nuclear Information System (INIS)

Hillsman, E.L.

1991-01-01

Policies to reduce greenhouse gas emissions from present levels will require changes in local and regional decision making as well as decisions made at national and multinational scales. A number of cities and states have taken action to reduce emissions either directly or as a byproduct of solving local problems such as air quality. These initiatives represent a potential resource to be mobilized in national policy. A series of case studies is under way to understand the decision making involved and its implications, and to identify ways that national policy might support and benefit from local efforts. Preliminary results from the first of these case studies indicate that reductions in greenhouse gas emissions may be greater when set as a direct target than when resulting as a byproduct of other local problem solving

Sand and gravel spits

CERN Document Server

Randazzo, Giovanni; Cooper, J Andrew G

2015-01-01

This book draws together a series of studies of spit geomorphology and temporal evolution from around the world. The volume offers some unique insights into how these landforms are examined scientifically and how we as humans impact them, offering a global perspective on spit genesis and evolution. Spits are unique natural environments whose evolution is linked to the adjacent coast and near shore morphology, sediment supply, coastal dynamics and sea-level change. Over the past century, Global Mean Sea Level (GMSL) has risen by 10 to 20 centimetres and many coastal spits represent the first sentinel against coastal submersion. Scientific research indicates that sea levels worldwide have been rising at a rate of 3.5 millimetres per year since the early 1990s, roughly twice the average speed of the preceding 80 years. This trend, linked to global warming will undoubtedly cause major changes in spit morphology. Spits are highly mobile coastal landforms that respond rapidly to environmental change. They therefore...

Interaction of the Bored Sand and Gravel Drain Pile with the Surrounding Compacted Loam Soil and Foundation Raft Taking into Account Rheological Properties of the Loam Soil and Non-Linear Properties of the Drain Pile

Science.gov (United States)

Ter-Martirosyan, Z. G.; Ter-Martirosyan, A. Z.; Anzhelo, G. O.; Buslov, A. S.

2018-01-01

The task of the interaction of the sand and gravel drain pile with the surrounding loam soil after its preliminary deep compaction and formation of the composite ground cylinder from the drain pile and surrounding compacted loam soil (cells) is considered in the article. It is seen that the subsidence and carrying capacity of such cell considerably depends on physical and mechanical properties of the compacted drain piles and surrounding loam soil as well as their diameter and intercellular distance. The strain-stress state of the cell is considered not taking into account its component elements, but taking into account linear and elastic-plastic properties of the drain pile and creep flow of the surrounding loam soil. It is stated that depending on these properties the distribution and redistribution of the load on a cell takes place from the foundation raft between the drain pile and surrounding soil. Based on the results of task solving the formulas and charts are given demonstrating the ratio of the load between the drain pile and surrounding loam soil in time.

Local and non-local equivalent potentials for p-12C scattering

International Nuclear Information System (INIS)

Lovell, A.; Amos, K.

2000-01-01

A Newton-Sabatier fixed energy inversion scheme has been used to equate inherently non-local p- 12 C potentials at a variety of energies to pion threshold, with exactly phase equivalent local ones. Those energy dependent local potentials then have been recast in the form of non-local Frahn-Lemmer interactions

New Paradigm for Local Financial Management: A Review of Local Budgeting System

Directory of Open Access Journals (Sweden)

Hendra Karianga

2016-12-01

Full Text Available Fiscal decentralization gives authority to the head of region and regional parliament to manage the local budget. The outcomes of the research indicate that the Good Financial Governance principle has been subject to frequent study in its understanding as a new paradigm for local financial management. As it turns out in practice, however, it has certain weaknesses, particularly in view of the accountability and legitimacy aspects of its establishment. In fact, the local budget has become a vehicle for corruption by the state administration is in the center of power, local autonomy shift some corruptor from the center to the local. The issue is how to manage the local budget in order to minimize corruption. If the commitment of the management of local budget is based on new principles in the local financial management, it believed that the local budget is governed annually by the local government will lead to the people’s welfare in the region. Based on such view, the Good Financial Governance principles appears to be the ideal approach to be applied in managing the local budgeting system.

Local conservation laws and the structure of the many-body localized states.

Science.gov (United States)

Serbyn, Maksym; Papić, Z; Abanin, Dmitry A

2013-09-20

We construct a complete set of local integrals of motion that characterize the many-body localized (MBL) phase. Our approach relies on the assumption that local perturbations act locally on the eigenstates in the MBL phase, which is supported by numerical simulations of the random-field XXZ spin chain. We describe the structure of the eigenstates in the MBL phase and discuss the implications of local conservation laws for its nonequilibrium quantum dynamics. We argue that the many-body localization can be used to protect coherence in the system by suppressing relaxation between eigenstates with different local integrals of motion.

Late Pleistocene Stratigraphy and Palaeobotany of the Isles of Scilly

Science.gov (United States)

Scourse, J. D.

1991-12-01

A re-evaluation of the Pleistocene stratigraphy of the Isles of Scilly has enabled the formal definition of eight lithostratigraphic units of member status grouped into two formations. A chronology of events has been provided by radiocarbon (14C) determinations, optical and thermoluminescene (TL) dates. Intersite correlations have been strengthened by palynology, which has aided palaeoenvironmental reconstruction. The defined units have been incorporated into two lithostratigraphic models, one for the `northern' (glacial) Scillies and one for the `southern' (extra-glacial) Scillies. Raised beach sediments of the Watermill Sands and Gravel in the southern Scillies are overlain by the Porthloo Breccia, a unit of soliflucted material derived exclusively from the weathering of local granite. Organic sequences at Carn Morval, Watermill Cove, Porth Askin, Porth Seal and Bread and Cheese Cove occur within the Porthloo Breccia, and are interpreted as the infillings of ponds associated with active solifluction. Radiocarbon determinations from these organic sediments are critical because they pre-date units associated with a glacial event. The 14C determinations indicate deposition of the organic material between 34500-800+885 (Q-2410) and 21500-800+890 (Q-2358) years BP and provide a maximum age for the glacial event and the first radiometric dates for the coastal `head' sediments of southwest England. The pollen assemblages from these organic sites all record open grassland vegetation, and represent the earliest vegetational record for the Scillies. High Pinus values are interpreted as evidence of climatic deterioration. In the southern Scillies, the Porthloo Breccia is overlain by the Old Man Sandloess, a coarse aeolian silt with subdominant fine sand, TL-dated to 18600-3700+3700 years (QTL-ld and lf; Wintle 1981) and optically dated to 20000-7000+7000 and 26000-9000+10000 years (two samples; 738al and 741al; Smith et al. 1990). This material occurs in a variety of facies

Introducing local property tax for fiscal decentralization and local authority autonomy

Science.gov (United States)

Dimopoulos, Thomas; Labropoulos, Tassos; Hadjimitsis, Diafantos G.

2015-06-01

Charles Tiebout (1956), in his work "A Pure Theory of Local Expenditures", provides a vision of the workings of the local public sector, acknowledging many similarities to the features of a competitive market, however omitting any references to local taxation. Contrary to other researchers' claim that the Tiebout model and the theory of fiscal decentralization are by no means synonymous, this paper aims to expand Tiebout's theory, by adding the local property tax in the context, introducing a fair, ad valorem property taxation system based on the automated assessment of the value of real estate properties within the boundaries of local authorities. Computer Assisted Mass Appraisal methodology integrated with Remote Sensing technology and GIS analysis is applied to local authorities' property registries and cadastral data, building a spatial relational database and providing data to be statistically processed through Multiple Regression Analysis modeling. The proposed scheme accomplishes economy of scale using CAMA procedures on one hand, but also succeeds in making local authorities self-sufficient through a decentralized, fair, locally calibrated property taxation model, providing rational income administration.

Plant growth evaluation of Cajanus cajan (L. Millsp., Canavalia ensiformis (L. DC. and Cratylia argentea (Desvaux O. Kuntze., in soils degraded by sand and gravel extraction

Directory of Open Access Journals (Sweden)

Mateo Vargas Zapata

2017-10-01

Full Text Available In this research, the adaptability of pigeon pea (Cajanus cajan (L. Millsp., canavalia (Canavalia ensiformis (L. DC. and veranera (Cratylia argentea (Desvaux O. Kuntze species, was evaluated in soils degraded by sand and gravel extraction. The three species were planted in bags as follows: 20 x 10cm, each with 3 seeds, with a substrate 2:1 soil and sand, respectively. The plants were grown under shadow conditions with 50% for 60 days, and received irrigation according to climate conditions. Therefore, were transplanted at field conditions, plant height (PH, fully developed leaves (FDL and stem diameter (SD variables, were measured every week for 10 weeks. A randomized block design was used with a fixed balanced effect. The number of replicates per treatment was four, the multivariate technique MANOVA variance with orthogonal type was included and the method of maximum likelihood was used to establish the dimensionality of the contrast. In fact, one-dimensional comparisons were carried out using Tukey method, which had achieved type I error of 5% statistical significance. Significant difference among plants for PH (p<0.05 variable was obtained. In addition, SD variable showed differences from the third week for all evaluated plants (p<0.05. A highly significant and directly proportional relationship among HP, FDL and SD variables (p<0.0001, was found. MANOVA Multivariate Analysis showed a highly significant difference among evaluated species (p<0.0001, which confirms the hypothesis. It was expected that species were developing and growing despite having contrasting conditions in the study area.

Relationship of bifenthrin sediment concentrations to grain size and total organic carbon in California waterbodies: implications for ecological risk.

Science.gov (United States)

Hall, Lenwood W; Anderson, Ronald D

2014-12-01

A summary analysis of data sets from six California waterbodies was conducted to determine the relationship of bifenthrin sediment concentrations to: % sand/gravel; % silt; % clay; % silt/clay and % total organic carbon (TOC). The relationship of TOC to % sand/gravel, % silt, % clay, and % silt/clay was also analyzed. Statistically significant and meaningful direct relationships were reported between bifenthrin and % TOC, % silt, % clay and % silt/clay while a significant and meaningful inverse relationship was reported between bifenthrin and % sand/gravel. A significant and meaningful inverse relationship was reported between % TOC and % sand/gravel, while a significant and meaningful direct relationship was reported between % TOC and % silt, % clay and % silt/clay. Significant bifenthrin sediment concentrations would not be expected in non-depositional (sand/gravel) areas which have been reported to be dominant in various streams in California's Central Valley and are also the preferred habitat for many benthic macroinvertebrate taxa.

Integrated mined-area reclamation and land use planning. Volume 3A. A case study of surface mining and reclamation planning: South Boulder Creek Park Project, Sand and Gravel Operations, Boulder, Colorado

Energy Technology Data Exchange (ETDEWEB)

Lewis, L R; Perry, A O; LaFevers, J R

1977-02-01

This case study details reclamation planning for the Flatiron Companies' South Boulder Creek Park Project in Boulder, Colorado. The site contains a deposit of high-quality sand and gravel considered to be one of the best and largest known deposits of aggregate materials in the Front Range area. The aggregate deposit is located in a highly visible site just off the Denver-Boulder Turnpike at the entrance to the city from Denver, and adjacent to a residential portion of the city. In order to make maximum use of pre-mining planning, as a tool for resolving a conflict over the company's proposed operation, an extensive cooperative planning effort was initiated. This included the preparation of an environmental impact assessment, numerous public hearings, operating and reclamation plan review by city authorities, annexation of the site to the city, and the granting of a scenic easement on the property to the city for the development of a regional recreation park. A suite of contractual agreements was worked out among Flatiron Companies, the City of Boulder, the Colorado Open Lands Foundation, and the Federal Bureau of Outdoor Recreation. The purpose of this case study is to allow the planner to gain insight into the procedures, possibilities, and constraints involved in premining planning in a cooperative situation.

Hydrogeologic framework of the middle San Pedro watershed, southeastern Arizona

Science.gov (United States)

Dickinson, Jesse; Kennedy, Jeffrey R.; Pool, D.R.; Cordova, Jeffrey T.; Parker, John T.; Macy, J.P.; Thomas, Blakemore

2010-01-01

the upper basin fill may be more permeable than the lower basin fill, but it is generally unsaturated in the study area. The lower basin fill stratigraphic unit was delineated into three HGUs on the basis of lithologic descriptions in driller?s logs and one-dimensional (1D) electrical models of airborne transient electromagnetic (TEM) surveys. The interbedded lower basin fill (ILBF) HGU represents an upper sequence having resistivity values between 5 and 40 ohm-m identified as interbedded sand, gravel, and clay in driller?s logs. Below this upper sequence, fine-grained lower basin fill (FLBF) HGU represents a thick silt and clay sequence having resistivity values between 5 and 20 ohm-m. Within the coarse-grained lower basin fill (CLBF) HGU, which underlies the silt and clay of the FLBF, the resistivity values on logs and 1D models increase to several hundred ohm-m and are highly variable within sand and gravel layers. These sequences match distinct resistivity and lithologic layers identified by geophysical logs in the adjacent Sierra Vista subwatershed, suggesting that these sequences are laterally continuous within both the Benson and Sierra Vista subwatersheds in the Upper San Pedro Basin. A subsurface density model based on gravity data was constructed to identify the top of bedrock and structures that may affect regional groundwater flow. The subsurface density model contains six layers having uniform density values, which are assigned on the basis of geophysical logs. The density values for the layers range between 1.65 g/cm3 for unsaturated sediments near the land surface and 2.67 g/cm3 for bedrock. Major features include three subbasins within the study area, the Huachuca City subbasin, the Tombstone subbasin, and the Benson subbasin, which have no expression in surface topography or lithology. Bedrock altitudes from the subsurface density model defined top altitudes of the bedrock HGU. The HFM includes the following HGUs in ascending stratigr

Local food and tourism

DEFF Research Database (Denmark)

Boesen, Morten; Sundbo, Donna; Sundbo, Jon

2017-01-01

This article investigates the question: Why local food networks succeed or fail in collaborating with local tourism actors to create more tourism based on local food? The article focuses on entrepreneurial local food networks and their collaboration with local tourism actors. Emphasis...... is on the actions and attitude logics of local food networks and tourism actors, and whether their respective logics fit as a factor to explain why or why not development of local food concepts lead to increased local tourism. Six local food networks and their collaboration with local tourism actors are studied...... by using observation supplemented with other qualitative methods. Analysis of these networks reveals that successful collaboration is characterised by the food networks and tourism actors having at least one logic in common. The fitting logics that lead to success are primarily celebrity and civic logics...

An Open Localization and Local Communication Embodied Sensor

Directory of Open Access Journals (Sweden)

Alvaro Gutiérrez

2008-11-01

Full Text Available In this paper we describe a localization and local communication system which allows situated agents to communicate locally, obtaining at the same time both the range and the bearing of the emitter without the need of any centralized control or any external reference. The system relies on infrared communications with frequency modulation and is composed of two interconnected modules for data and power measurement. Thanks to the open hardware license under which it is released, the research community can easily replicate the system at a low cost and/or adapt it for applications in sensor networks and in robotics.

Bedform migration in steep channels: from local avalanches to large scale changes

Science.gov (United States)

Mettra, F.; Heyman, J.; Ancey, C.

2013-12-01

Many studies have emphasized the strength of bedload transport fluctuations in steep streams, especially at low and intermediate transport conditions (relative to the threshold of incipient motion). The origins of these fluctuations, which appear on a wide range of time scales, are still not well understood. In this study, we present the data obtained from a 2D idealized laboratory experiment with the objective of simultaneously recording the channel bed evolution and bedload transport rate at a high temporal resolution. A 3-m long by 8-cm wide transparent flume filled with well-sorted natural gravel (d50=6.5 mm) was used. An efficient technique using accelerometers has been developed to record the arrival time of every particle at the outlet of the flume for long experimental durations (up to a few days). In addition, bed elevation was monitored using cameras filming from the side of the channel, allowing the observation of global aggradation/degradation as well as bedform migration. The experimental parameters were the water discharge, the flume inclination (from 2° to 5°) and the constant feeding rate of sediments. Large-scale bed evolution showed successive aggradation and rapid degradation periods. Indeed, the measured global channel slope, i.e. mean slope over the flume length, fluctuated continuously within a range sometimes wider than 1° (experimental parameters were constant over the entire run). The analysis of these fluctuations provides evidence that steep channels behave like metastable systems, similarly to grain piles. The metastable effects increased for steeper channels and lower transport conditions. In this measurement campaign, we mainly observed upstream-migrating antidunes. For each run, various antidune heights and celerities were measured. On average, the mean antidune migration rate increased with decreasing channel slope and increasing sediment feeding rate. Relatively rare tall and fast-moving antidunes appeared more frequently at high

Generalized hydrogeologic framework and groundwater budget for a groundwater availability study for the glacial aquifer system of the United States

Science.gov (United States)

Reeves, Howard W.; Bayless, E. Randall; Dudley, Robert W.; Feinstein, Daniel T.; Fienen, Michael N.; Hoard, Christopher J.; Hodgkins, Glenn A.; Qi, Sharon L.; Roth, Jason L.; Trost, Jared J.

2017-12-14

The glacial aquifer system groundwater availability study seeks to quantify (1) the status of groundwater resources in the glacial aquifer system, (2) how these resources have changed over time, and (3) likely system response to future changes in anthropogenic and environmental conditions. The glacial aquifer system extends from Maine to Alaska, although the focus of this report is the part of the system in the conterminous United States east of the Rocky Mountains. The glacial sand and gravel principal aquifer is the largest source of public and self-supplied industrial supply for any principal aquifer and also is an important source for irrigation supply. Despite its importance for water supply, water levels in the glacial aquifer system are generally stable varying with climate and only locally from pumping. The hydrogeologic framework developed for this study includes the information from waterwell records and classification of material types from surficial geologic maps into likely aquifers dominated by sand and gravel deposits. Generalized groundwater budgets across the study area highlight the variation in recharge and discharge primarily driven by climate.

Local expression of global forcing factors in Lower Cretaceous, Aptian carbon isotope segment C5: El Pujal Section, Organya Basin, Catalunya, Spain.

Science.gov (United States)

Socorro, J.; Maurrasse, F. J.

2017-12-01

During the Aptian, the semi-restricted Organya Basin accumulated sediments under quasi-continuous dysoxic conditions [1]. High resolution stable carbon isotope (δ13Corg) values for 71.27 m of interbedded limestones, argillaceous limestones and marlstones of the El Pujal sequence show relatively small variability (1.65‰) fluctuating between -25.09‰ and -23.44‰ with an average of -24.02‰. This pattern is consistent with values reported for other Tethyan sections for carbon isotope segment C5 [2]. The geochemical and petrographic results of the sequence, reveal periodic enrichment of redox sensitive trace elements (V, Cr, Co, Ni, Cu, Mo, U), biolimiting (P, Fe) and major elements (Al, Si, Ti) at certain levels concurrent with episodes of enhanced organic carbon preservation (TOC). Inorganic carbonate (TIC) dilution due to significant clay fluxes is also evident along these intervals as illustrated by the strong negative correlation with Al (r = -0.91). Microfacies characterized by higher pyrite concentration, impoverished benthic fauna and lower degree of bioturbation index (3) are in accord with geochemical proxies. When combined, these results suggest recurrent intermittent dysoxic conditions associated with episodic increases of terrigenous supplies by riverine fluxes, which are in agreement with results reported for the basal segment of the section (0-13.77m) [3]. Concurrently, δ13Corg values show a positive correlation with TIC (r = 0.50) and a negative correlation with TOC (r = -0.46), thus showing more negative values corresponding with intervals of highest terrestrial influences, which were previously correlated with higher inputs of higher chain (>nC25) n-alkanes [3]. Hence, the results highlight the local expression of the δ13Corg signal related to higher inputs of terrestrial vegetation linked with lower δ13Corg values modulating the global signature of segment C5. References: [1] Sanchez-Hernandez & Maurrasse, 2016. Palaeo3 441; [2] Menegatti

Active Neural Localization

OpenAIRE

Chaplot, Devendra Singh; Parisotto, Emilio; Salakhutdinov, Ruslan

2018-01-01

Localization is the problem of estimating the location of an autonomous agent from an observation and a map of the environment. Traditional methods of localization, which filter the belief based on the observations, are sub-optimal in the number of steps required, as they do not decide the actions taken by the agent. We propose "Active Neural Localizer", a fully differentiable neural network that learns to localize accurately and efficiently. The proposed model incorporates ideas of tradition...

Ground-water availability in the central part of Lake Ontario basin, New York

Science.gov (United States)

Miller, Todd S.; Krebs, Martha M.

1988-01-01

A set of three maps showing surficial geology, distribution of glacial aquifers, and potential well yield in the 708 sq mi central part of the Lake Ontario basin are presented at a scale of 1:125,000. The basin is parallel to Lake Ontario and extends from Rochester in the west to Oswego in the east. Aquifers consisting primarily of sand and gravel formed where meltwaters from glaciers deposited kame and outwash sand and gravel and where wave action along shores of glacial lakes eroded, reworked , and deposited beaches. Thick deposits of well-sorted sand and gravel yield relatively large quantities of water - typically more than 100 gal/min. Aquifers consisting of thin beds of sand and (or) gravel or thick gravel that contain a large proportion of silt and fine sand yield moderate amounts of water, 10 to 100 gal/min. Dug and driven wells that tap fine to medium sand deposits typically yield 1 to 10 gal/min. (USGS)

A Morphing framework to couple non-local and local anisotropic continua

KAUST Repository

Azdoud, Yan

2013-05-01

In this article, we develop a method to couple anisotropic local continua with anisotropic non-local continua with central long-range forces. First, we describe anisotropic non-local models based on spherical harmonic descriptions. We then derive compatible classic continuum models. Finally, we apply the morphing method to these anisotropic non-local models and present three-dimensional numerical examples to validate the efficiency of the technique. © 2013 Elsevier Ltd. All rights reserved.

Final Oahe Dam/Lake Oahe Master Plan Missouri River, South Dakota and North Dakota

Science.gov (United States)

2010-09-01

silty loams with moderate erosion and poor permeability. Normally used for pastureland. Sansarc- Opal : clays with minor erosion and permeability...One active sand and gravel mining area is located on Oahe project lands at Fort Yates, North Dakota. There is also a small amount of sand and...consist of sand and gravel deposits and Pierre Shale. The sand and gravel deposits are mined for road construction materials and concrete aggregate

Microbialites and global environmental change across the Permian-Triassic boundary: a synthesis.

Science.gov (United States)

Kershaw, S; Crasquin, S; Li, Y; Collin, P-Y; Forel, M-B; Mu, X; Baud, A; Wang, Y; Xie, S; Maurer, F; Guo, L

2012-01-01

Permian-Triassic boundary microbialites (PTBMs) are thin (0.05-15 m) carbonates formed after the end-Permian mass extinction. They comprise Renalcis-group calcimicrobes, microbially mediated micrite, presumed inorganic micrite, calcite cement (some may be microbially influenced) and shelly faunas. PTBMs are abundant in low-latitude shallow-marine carbonate shelves in central Tethyan continents but are rare in higher latitudes, likely inhibited by clastic supply on Pangaea margins. PTBMs occupied broadly similar environments to Late Permian reefs in Tethys, but extended into deeper waters. Late Permian reefs are also rich in microbes (and cements), so post-extinction seawater carbonate saturation was likely similar to the Late Permian. However, PTBMs lack widespread abundant inorganic carbonate cement fans, so a previous interpretation that anoxic bicarbonate-rich water upwelled to rapidly increase carbonate saturation of shallow seawater, post-extinction, is problematic. Preliminary pyrite framboid evidence shows anoxia in PTBM facies, but interbedded shelly faunas indicate oxygenated water, perhaps there was short-term pulsing of normally saturated anoxic water from the oxygen-minimum zone to surface waters. In Tethys, PTBMs show geographic variations: (i) in south China, PTBMs are mostly thrombolites in open shelf settings, largely recrystallised, with remnant structure of Renalcis-group calcimicrobes; (ii) in south Turkey, in shallow waters, stromatolites and thrombolites, lacking calcimicrobes, are interbedded, likely depth-controlled; and (iii) in the Middle East, especially Iran, stromatolites and thrombolites (calcimicrobes uncommon) occur in different sites on open shelves, where controls are unclear. Thus, PTBMs were under more complex control than previously portrayed, with local facies control playing a significant role in their structure and composition. © 2011 Blackwell Publishing Ltd.

Local network assessment

Science.gov (United States)

Glen, D. V.

1985-04-01

Local networks, related standards activities of the Institute of Electrical and Electronics Engineers the American National Standards Institute and other elements are presented. These elements include: (1) technology choices such as topology, transmission media, and access protocols; (2) descriptions of standards for the 802 local area networks (LAN's); high speed local networks (HSLN's) and military specification local networks; and (3) intra- and internetworking using bridges and gateways with protocols Interconnection (OSI) reference model. The convergence of LAN/PBX technology is also described.

Current algebra and the local nature of symmetries in local quantum theory

International Nuclear Information System (INIS)

Doplicher, S.

In this report we mainly discuss the problem of finding local observables which measure the charges in a volume smaller than their localization region, in particular providing the existence of local observables with a specific physical interpretation. In the same way we can also establish the existence of a version of the current algebra structure. Similar local observables can be constructed for the energy-momentum; we also comment on the local implementation of supersymmetries. (orig./HSI)

Local government financial autonomy in Nigeria: The State Joint Local Government Account

Directory of Open Access Journals (Sweden)

Jude Okafor

2010-07-01

Full Text Available This paper addresses the statutory financial relations and financial autonomy of local government in Nigeria, and the freedom of local government to generate revenue from its assigned sources without external interference. It focuses particularly on a financial instrument called the State Joint Local Government Account (SJLGA and how its operations have positively or negatively affected the financial autonomy of local government councils and the inter-relations between state and local government in Nigeria.

String-localized quantum fields

International Nuclear Information System (INIS)

Mund, Jens; Santos, Jose Amancio dos; Silva, Cristhiano Duarte; Oliveira, Erichardson de

2009-01-01

Full text. The principles of physics admit (unobservable) quantum fields which are localized not on points, but on strings in the sense of Mandelstam: a string emanates from a point in Minkowski space and extends to infinity in some space-like direction. This type of localization might permit the construction of new models, for various reasons: (a) in general, weaker localization implies better UV behaviour. Therefore, the class of renormalizable interactions in the string-localized has a chance to be larger than in the point-localized case; (b) for certain particle types, there are no point-localized (free) quantum fields - for example Anyons in d = 2 + 1, and Wigner's massless 'infinite spin' particles. For the latter, free string-localized quantum fields have been constructed; (c) in contrast to the point-localized case, string-localization admits covariant vector/tensor potentials for fotons and gravitons in a Hilbert space representation with positive energy. We shall present free string-localized quantum fields for various particle types, and some ideas about the perturbative construction of interacting string-localized fields. A central point will be an analogue of gauge theories, completely within a Hilbert space and without ghosts, trading gauge dependence with dependence on the direction of the localization string. In order to discuss renormalizability (item (a)), methods from microlocal analysis (wave front set and scaling degree) are needed. (author)

BELLO, OM; UDUMA, AU

African Journals Online (AJOL)

ADOWIE PERE

2018-03-16

Mar 16, 2018 ... interbedded sandstones and shale with minor lignite organized into coarsening ... oil and gas are usually trapped in rollover anticlines associated with ... Extraction and analysis: Rock samples were crushed into powder < 100 ...

Local Social Networks

DEFF Research Database (Denmark)

Sapuppo, Antonio; Sørensen, Lene Tolstrup

2011-01-01

Online social networks have become essential for many users in their daily communication. Through a combination of the online social networks with opportunistic networks, a new concept arises: Local Social Networks. The target of local social networks is to promote social networking benefits...... in physical environment in order to leverage personal affinities in the users' surroundings. The purpose of this paper is to present and discuss the concept of local social networks as a new social communication system. Particularly, the preliminary architecture and the prototype of local social networks...

Gravel size matters: Early Middle Palaeolithic artefacts made from local Rhine and Meuse deposits in the central Netherlands

NARCIS (Netherlands)

van den Biggelaar, D.F.A.M.; van Balen, R.T.; Kluiving, S.J.; Verpoorte, A.; Alink, A

2016-01-01

The artefact size of the Early Middle Palaeolithic (EMP) assemblages in ice-pushed Rhine–Meuse deposits in the central Netherlands decreases northwestward. This trend correlates to the downstream fining direction of the Rhine–Meuse fluvial system, the source of the rock material, showing that

Globalization vs. localization: global food challenges and local sollutions

NARCIS (Netherlands)

Quaye, W.; Jongerden, J.P.; Essegbey, G.; Ruivenkamp, G.T.P.

2010-01-01

The objective of this study was to examine the effect of global-local interactions on food production and consumption in Ghana, and identify possible local solutions. Primary data were collected using a combination of quantitative-qualitative methods, which included focus group discussions and

Solving local problems through local involvement? Experiences from Danish Urban Regeneration

DEFF Research Database (Denmark)

Jensen, Jesper Ole

-down approaches or massive public subsidies, the public regeneration schemes from the last decade have increasingly emphasized the need for involving local actors in the urban regeneration e.g. through partnerships, network building, involvement and participation of local actors and institutions, and financially...... agenda, and what can be learned from the development so far. Although ‘local involvement’ is a commonly used term in various urban regeneration programs, it can have many different meanings and implications. Therefore, the paper will discuss local involvement in the urban regeneration based on four...

Local Exhaust Ventilation

DEFF Research Database (Denmark)

Madsen, Ulla; Breum, N. O.; Nielsen, Peter V.

Capture efficiency of a local exhaust system, e.g. a kitchen hood, should include only contaminants being direct captured. In this study basic concepts of local exhaust capture efficiency are given, based on the idea of a control box. A validated numerical model is used for estimation of the capt......Capture efficiency of a local exhaust system, e.g. a kitchen hood, should include only contaminants being direct captured. In this study basic concepts of local exhaust capture efficiency are given, based on the idea of a control box. A validated numerical model is used for estimation...

Production de minitubercules de pomme de terre par hydroponie: évaluation d'un système combinant les techniques NFT et Gravel Culture pour deux types de solutions nutritives

Directory of Open Access Journals (Sweden)

Rolot J.L.

2002-01-01

Full Text Available Potato minituber production through hydropony: assessment of a system combining the NFT and Gravel Culture techniques for two types of nutrient solutions. The potato minituber production is the classical intermediate stage enabling field use of potato materials with an in vitro origin. This production of minitubers may be achieved through various techniques. Most often however they are based upon bedding vitroplantlets or vitroplantlets cuttings in an organic substratum which is disinfected or not. The soilless culture of plants stemming from vitrotubers to produce minitubers with a superior health quality was tested within a hydroponic system. Two types of nutrient solutions were compared: a nitrogen rich one (NPK, mg/l, 180-40-300 and a phosphorus rich one (NPK, mg/l, 60-150-300. In order to initiate the cultures, presprouting microtubers of several varieties (Bintje, Kennebec, Spunta, Saturna, Desiree and Gasore were used. Multiplication rates ranged between 13.2 (Saturna and 3.8 (Kennebec minitubers with a grade higher than 10 mm (more than 1.5 g. As the selected density of the plants was 59 plants per square metre, the yield per square metre varied from 224 to 779 minitubers with a grade higher than 10 mm. The obtained number of minitubers depended especially on the variety. The phosphorus enrichment of the nutrient solution induced an increased number of minitubers produced with a grade higher than 15 mm (more than 5 g. The health state of the produced tubers was excellent.

Local E11

International Nuclear Information System (INIS)

Riccioni, Fabio; West, Peter

2009-01-01

We give a method of deriving the field-strengths of all massless and massive maximal supergravity theories in any dimension starting from the Kac-Moody algebra E 11 . Considering the subalgebra of E 11 that acts on the fields in the non-linear realisation as a global symmetry, we show how this is promoted to a gauge symmetry enlarging the algebra by the inclusion of additional generators. We show how this works in eleven dimensions, and we call the resulting enlarged algebra E 11 local . Torus reduction to D dimensions corresponds to taking a subalgebra of E 11 local , called E 11,D local , that encodes the full gauge algebra of the corresponding D-dimensional massless supergravity. We show that each massive maximal supergravity in D dimensions is a non-linear realisation of an algebra E-tilde 11,D local . We show how this works in detail for the case of Scherk-Schwarz reduction of IIB to nine dimensions, and in particular we show how E-tilde 11,9 local arises as a subalgebra of the algebra E 11,10B local associated to the ten-dimensional IIB theory. This subalgebra corresponds to taking a combination of generators which is different to the massless case. We then show that E-tilde 11,D local appears as a deformation of the massless algebra E 11,D local in which the commutation relations between the E 11 and the additional generators are modified. We explicitly illustrate how the deformed algebra is constructed in the case of massive IIA and of gauged five-dimensional supergravity. These results prove the naturalness and power of the method.

THE RELATIONSHIP BETWEEN THE CONTENT OF IRON AND COPPER IN THE SOILS AND WINES FROM THE LOCAL VINEYARDS OF THE CONTINENTAL CROATIA: A PRELIMINARY RESEARCH

Directory of Open Access Journals (Sweden)

Stanko Ružičić

2014-12-01

Full Text Available Samples of red and white wine together with corresponding soils from the domestic vineyards of the continental Croatia were selected for analysis. Vineyard soil cover (Stagnosols and Rendzina is developed over the Plio-Quaternary non-consolidated deposits (gravel, sand, silt, clay or marly limestones. Within soils overlying non-consolidated deposits containing clays pH value range from 5.4 to 6.6, whereas maximum measured pH of 7.5 is attributed to soil developed over marly limestones. Soil and wine samples was determined by the total content of copper and iron using flame atomic absorption spectrometry (FAAS. Results are compared to the maximum permitted concentrations (MPC by the relevant Croatian regulations. Copper concentrations are elevated within all measured wines (from 1.7× to 2.0× with respect to MPC and two soil samples (up to 2.4× with respect to MPC, due to extensive use of agrochemicals in the vineyards. Increased concentrations of iron within wine and corresponding soil were determined at locality with low soil pH (5.5. Preliminary research demonstrates a plausible link between the content of elements within soils developed over a specific lithology and associated wines. Increased copper concentration within wines of domestic production points to need for education of population in line with use of eco-agrochemicals. Further extensive studies with detailed physico-chemical processing of soil samples are needed (the paper is published in Croatian.

Local and non-local potentials for deuteron elastic scattering

International Nuclear Information System (INIS)

Ramirez, J.A.

1976-01-01

The nucleon--nucleus local potential (central and spin--orbit) and the deuteron--nucleus nonlocal potential (central, spin--orbit, spin--radial tensor) are calculated by the folding-model (FM). Simple analytic expressions are obtained for the nucleon--nucleus potential by the use of Gaussians to represent the nucleon--nucleus potential and the charge and mass densities of the target. The analytic expressions give qualitative descriptions of phenomenological nucleon--nucleus interactions. A systematic target--mass dependence of realistic local FM deueron potentials is also included. Local-equivalent, energy-dependent, deuteron potentials are obtained from the nonlocal FM deuteron potentials and the energy dependence of the local potential parameters are presented. The local FM deuteron potential is tested for 60 Ni(d,d) 60 Ni at E/sub α/ = 15 MeV by comparing the predictions of the FM potentials with data in which all five polarization moments were measured. A qualitative fit to the data is obtained, but it overestimates the volume integral of the central potential by 7%. Energy-dependence effects are estimated by evaluating the local-equivalent potentials at E/sub α/ = 30 MeV and comparing the predictions to the E/sub α/ = 15 MeV potentials. The energy dependence of the central potential dominates the angular dependence of all five observables while the energy dependence of the spin--orbit and tensor potentials produces only scale changes (approx. 3%) in the vector and tensor analyzing powers. The scattering formalism for a spin-1 on a spin-0 target nucleus, and a description of the coupled--channels computer code DDUNC1 which treats the spin--radial tensor potential exactly, are included

Economic geology of the Zipaquira quadrangle and adjoining area, Department of Cundinamarca, Colombia

Science.gov (United States)

McLaughlin, Donald H.; Arce Herrera, Marino

1970-01-01

At least four evaporite sequences are interbedded with Cretaceous strata in the Bogotga area of the Cordillera Oriental of Colombia. The easternmost and oldest evaporite interval is of probable Berriasian-Valanglnian age; the next oldest is of probable late Barremian-early Aptian age, and is followed by a possible late Aptian sequence. The westernmost and best known sequence is Turonian-early Coniacian in age, in the Sabana de Bogota. This youngest sequence contains the thickest known salt deposits and is probably the most widespread geographically. Three gypsum deposits of probable Barremian-Valanginian age are in the eastern part of the area under investigation. These deposits may have been leached from former salt accumulations. No other evaporites are exposed, but numerous brine springs are known, That the sources of these brines are neither deep not distant is suggested by the generally high concentrations, of the brines, the local presence of rute (leached salt residue), and the commonly significant amounts of H2S gas emitted at these springs. The rock salt exposed in three accessible mines commonly has a characteristic lamination caused by alternating layers of relatively pure halite and very argillaceous halite. Ubiquitously scattered throughout all salt deposits are small clasts of black, commonly pyritic, marly claystone. This lithology is also present as large claystone bodies conformably interbedded in the salt strata. Anhydrite is rare and is apparently more abundant at the Zipaquira mine that at the Nemocon and Upin mine. Paleontologic evidence in the Sabana de Bogota demonstrates that the salt-claystone series, hematite impregnated strata, and carbonaceous to locally coaly claystone are coeval. The salt-claystone facies may have been deposited in shallow evaporite pans that were separated within the overall evaporite interval by barriers on which the locally hematitic strata were deposited. The carbonaceous facies may also have formed in barrier

76 FR 47009 - Marine Mammals; Incidental Take During Specified Activities

Science.gov (United States)

2011-08-03

... and Beaufort Sea planning areas. Lease sale data are available on the ADNR Web site at: http://www.dog... recording facilities and communication equipment); building gravel pads; building gravel islands with...

Performance of a mixed-waste landfill amid geologic uncertainty—learning from a case study: Altamont Hills, California, U.S.A.

Science.gov (United States)

Taffet, Michael J.; Lamarre, Albert L.; Oberdorfer, June A.

1991-11-01

This paper presents a case study that illustrates how geologic factors, which are not always obvious without extensive study, may hamper later landfill performance. The site is Lawrence Livermore National Laboratory (LLNL) site 300. Two unlined landfills, opened in 1958, and 1968, contain small amounts of tritium, uranium-238, lead, and beryllium in a vast proportion of inert materials (gravel, wood, and plastic). Groundwater analyses indicate that tritium at activities up to 600,000 picoCuries per liter (pCi/l) is present in two plumes beneath and adjacent to the landfills within a perched water-bearing zone. The affected water-bearing zone averages 2 m in thickness and occurs within the late Miocene Neroly Formation, which is composed of feldspathic sandstones and siltstones and interbedded claystones and conglomerates. Scanning election microscopy (SEM) analysis indicates that diagenetic clays have occluded the porosity of much of the sandstones. However, abundant fractures appear to provide permeability. Depth to the water table fluctuates greatly beneath the site but averages about 10 m. In the past, following heavy rains, groundwater levels rose into the landfill bottoms and mobilized the tritium. Rapid recharge and rise of water levels appear to have been enhanced by the funnelling of surface water by topography, direct infiltration through fractures and permeable landfill materials, and the low permeability of the geologic materials that comprise the water-bearing zone. These and other hydrogeologic conditions contributed to groundwater contact with landfill materials but were not known before landfill construction. Such information is important for siting landfills in the current regulatory environment. Contaminant transport modeling indicates that even if the perched water-bearing zone were continuous to the site 300 boundary, tritium activities would undergo radioactive decay to background levels by the time the tritiated water could reach the site

Analysis of Deformation Characteristics and Stability Mechanisms of ...

Indian Academy of Sciences (India)

21

analysis of landslide mass under the similar engineering geological ... The bedrock mainly consists of the green-gray marlite of the thin layer, the interbedded dolomitic limestone and the purple-red mudstone of the Badong Formation from the ...

Evolution of the Southern Margin of the Donbas (Ukraine) from Devonian to early Carboniferous Times.

NARCIS (Netherlands)

McCann, T.; Saintot, A.N.

2003-01-01

A Devonian-Early Carboniferous succession comprising thick clastic and carbonate sediments with interbedded volcanics was examined along the southern margin of the Donbas fold belt. Ukraine. Following initial rifting and subsidence, a continental (fluvial, lacustrine) succession was established.

A digital local studies collection

Directory of Open Access Journals (Sweden)

Simona Resman

2005-01-01

Full Text Available Local studies and local studies departments reflect the entire spectrum of knowledge within the local community. Transition to the new digital environment means just continuing the basic functions of local studies collections: acquisition, cataloguing and preservation of materials in different formats on different media. The background of each digital library is the technical architecture of system that enables interaction between the user and the library, saving digital material and building a platform for searching and indexing digital objects. Using advanced ICT requests from librarians, designers of digital local studies collections a reflection about traditional roles. A digital local studies collection with new technology enlarges local boarders, local contents become more and more interesting for a wider sphere of people. In collecting of local materials a collaboration with archives and museums, with academic community, with community groups and with individuals comes in forefront. Digital local studies collections with their contents support local diversity, lifelong learning and social inclusion. The crucial elements of a digital local studies collection are attractive local contents with fast and simple access from one place – a portal. In the digital age public libraries become managers of knowledge also by establishing digital local studies collections.

Locally Finite Root Supersystems

OpenAIRE

Yousofzadeh, Malihe

2013-01-01

We introduce the notion of locally finite root supersystems as a generalization of both locally finite root systems and generalized root systems. We classify irreducible locally finite root supersystems.

Sex education for local tourism/hospitality employees: addressing a local health need.

Science.gov (United States)

Bauer, Irmgard L

2009-11-01

Health concerns arising from sexual relationships between tourists and locals usually focus on the travelling public. The local sex partners' health, and their impact on their communities' health, seem far less acknowledged. This paper describes a local health education session which implemented recommendations based on a study in Cuzco/Peru on tourists' and locals' views, knowledge, attitudes and experiences relating to sexual relationships between them. On location, fifteen discotheque employees received a health education session at the establishment's owner's request. Concluding from the positive experience, it is argued that researchers should, where possible, respond to requests to deliver ad hoc health education sessions while on location to address an identified local health need.

Efficiency of sewage treatment with septic tanks followed by constructed wetlands with different support materials

Directory of Open Access Journals (Sweden)

Delvio Sandri

2013-04-01

Full Text Available This study seeks to assess the efficiency of a sewage treatment plant comprised of three compartmentalized septic tanks installed in series followed by three parallel wetlands and seeded with species Typha sp. with subsurface flow, filled with support material of natural gravel, gravel # 2 and washed gravel, respectively. The station treats sewage generated at Unity University for Science and Technology, State University of Goiás – UnUCET/UEG. A total of 20 sewage samples were collected in order to evaluate treatment efficiency from November to December 2010 and March to April 2011. The points of analysis were at the input of the first tank (raw sewage, the output of the third septic tank and the outputs of each of the three wetlands. The total removal efficiencies were: 65.40% for chemical oxygen demand; 79.01% for biochemical oxygen demand; 59.79% for total solids; 87.12% for the total suspended solids; 92.00% for total coliforms; 95.71% for E. coli and 82.54% for turbidity. The system was effective for the treatment of sewage, within the current legislative parameters for pH, turbidity, total solids and biochemical oxygen demand. No significant difference was observed between the three different means of support, suggesting that gravel, natural gravel and washed gravel may potentially be used to fill wetlands.

Radon entry into buildings: Effects of atmospheric pressure fluctuations and building structural factors

Energy Technology Data Exchange (ETDEWEB)

Robinson, Allen Lantham [Univ. of California, Berkeley, CA (United States). Dept. of Mechanical Engineering

1996-05-01

An improved understanding of the factors that control radon entry into buildings is needed in order to reduce the public health risks caused by exposure to indoor radon. This dissertation examines three issues associated with radon entry into buildings: (1) the influence of a subslab gravel layer and the size of the openings between the soil and the building interior on radon entry; (2) the effect of atmospheric pressure fluctuations on radon entry; and (3) the development and validation of mathematical models which simulate radon and soil-gas entry into houses. Experiments were conducted using two experimental basements to examine the influence of a subslab gravel layer on advective radon entry driven by steady indoor-outdoor pressure differences. These basement 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 measurements indicate that a high permeability subslab gravel layer increases the advective radon entry rate into the structure by as much as a factor of 30. The magnitude of the enhancement caused by the subslab gravel layer depends on the area of the openings in the structure floor; the smaller the area of these openings the larger the enhancement in the radon entry rate caused by the subslab gravel layer. A three-dimensional, finite-difference model correctly predicts the effect of a subslab gravel layer and open area configuration on advective radon entry driven by steady indoor-outdoor pressure differences; however, the model underpredicts the absolute entry rate into each structure by a factor of 1.5.

Radon entry into buildings: Effects of atmospheric pressure fluctuations and building structural factors

International Nuclear Information System (INIS)

Robinson, A.L.

1996-05-01

An improved understanding of the factors that control radon entry into buildings is needed in order to reduce the public health risks caused by exposure to indoor radon. This dissertation examines three issues associated with radon entry into buildings: (1) the influence of a subslab gravel layer and the size of the openings between the soil and the building interior on radon entry; (2) the effect of atmospheric pressure fluctuations on radon entry; and (3) the development and validation of mathematical models which simulate radon and soil-gas entry into houses. Experiments were conducted using two experimental basements to examine the influence of a subslab gravel layer on advective radon entry driven by steady indoor-outdoor pressure differences. These basement 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 measurements indicate that a high permeability subslab gravel layer increases the advective radon entry rate into the structure by as much as a factor of 30. The magnitude of the enhancement caused by the subslab gravel layer depends on the area of the openings in the structure floor; the smaller the area of these openings the larger the enhancement in the radon entry rate caused by the subslab gravel layer. A three-dimensional, finite-difference model correctly predicts the effect of a subslab gravel layer and open area configuration on advective radon entry driven by steady indoor-outdoor pressure differences; however, the model underpredicts the absolute entry rate into each structure by a factor of 1.5

A hybrid local/non-local framework for the simulation of damage and fracture

KAUST Repository

Azdoud, Yan

2014-01-01

Recent advances in non-local continuum models, notably peridynamics, have spurred a paradigm shift in solid mechanics simulation by allowing accurate mathematical representation of singularities and discontinuities. This doctoral work attempts to extend the use of this theory to a community more familiar with local continuum models. In this communication, a coupling strategy - the morphing method -, which bridges local and non-local models, is presented. This thesis employs the morphing method to ease use of the non-local model to represent problems with failure-induced discontinuities. First, we give a quick review of strategies for the simulation of discrete degradation, and suggest a hybrid local/non-local alternative. Second, we present the technical concepts involved in the morphing method and evaluate the quality of the coupling. Third, we develop a numerical tool for the simulation of the hybrid model for fracture and damage and demonstrate its capabilities on numerical model examples

Many-body-localization: strong disorder perturbative approach for the local integrals of motion

Science.gov (United States)

Monthus, Cécile

2018-05-01

For random quantum spin models, the strong disorder perturbative expansion of the local integrals of motion around the real-spin operators is revisited. The emphasis is on the links with other properties of the many-body-localized phase, in particular the memory in the dynamics of the local magnetizations and the statistics of matrix elements of local operators in the eigenstate basis. Finally, this approach is applied to analyze the many-body-localization transition in a toy model studied previously from the point of view of the entanglement entropy.

[Local anaesthesia in ruminants].

Science.gov (United States)

Nuss, Karl; Schwarz, Andrea; Ringer, Simone

2017-06-20

The use of local anaesthesia in ruminants allows many surgical procedures to be conducted free of pain, efficiently and inexpensively in the field. Local anaesthesia combined with sedation and immobilisation of the animal can replace general anaesthesia for many procedures (e. g. castration, claw amputation). The level of difficulty differs among various local anaesthetic techniques: local infiltration of tissue or anaesthesia of the cornual nerve are easily performed, whereas local anaesthesia of the eye, regional anaesthesia in limbs or anaesthesia for umbilical surgery are more difficult to carry out. This article presents an illustrated overview of the most common local anaesthetic procedures in cattle as well as in small ruminants and serves as a practical guide for veterinarians in the field. In principle, these techniques can likewise be applied in other ruminants or artiodactyls.

Ecological restoration of Central European mining sites: a summary of a multi-site analysis

Energy Technology Data Exchange (ETDEWEB)

Prach, K.; Rehounkova, K.; Rehounek, J.; Konvalinkova, P. [University of South Bohemia, Ceske Budejovice (Czech Republic)

2011-07-01

Sites disturbed by mining were surveyed in the Czech Republic, central Europe. The sites included spoil heaps from coal mining, sand and gravel pits, extracted peatlands and stone quarries. The following main conclusions emerged: I) potential for spontaneous succession to be used in restoration projects is between 95 and 100% of the total area disturbed; ii) mining sites, if mining is properly designed and then the sites are left to spontaneous succession, often act as refugia for endangered and retreating organisms, and may contribute substantially to local biodiversity.

Measurement of the spatial specific impulse distribution due to buried high explosive charge detonation

Directory of Open Access Journals (Sweden)

V. Denefeld

2017-06-01

The momentum transfer to a vehicle depends on a number of influencing factors such as: charge mass, embedding material (e.g. sand, gravel, clay, density, water content, saturation, depth of burial, ground clearance and vehicle shape. The presented technology is applied to quantify the influence of the embedding material (alluvial sand, quartz sand, the burial depth and the water content on the local specific impulse distribution. The obtained data can be used as initial condition for the numerical simulation of occupant safety assessment and as input for empirical modeling of momentum transfer on structures.

Approach of simultaneous localization and mapping based on local maps for robot

Institute of Scientific and Technical Information of China (English)

CHEN Bai-fan; CAI Zi-xing; HU De-wen

2006-01-01

An extended Kalman filter approach of simultaneous localization and mapping(SLAM) was proposed based on local maps.A local frame of reference was established periodically at the position of the robot, and then the observations of the robot and landmarks were fused into the global frame of reference. Because of the independence of the local map, the approach does not cumulate the estimate and calculation errors which are produced by SLAM using Kalman filter directly. At the same time, it reduces the computational complexity. This method is proven correct and feasible in simulation experiments.

On A Quasi-local Mass

OpenAIRE

Zhang, Xiao

2009-01-01

We modify previous quasi-local mass definition. The new definition provides expressions of the quasi-local energy, the quasi-local linear momentum and the quasi-local mass. And they are equal to the ADM expressions at spatial infinity. Moreover, the new quasi-local energy has the positivity property.

Sedimentology and facies analysis of Devonian Rocks, southern district of Mackenzie, North West Territories, Canada

NARCIS (Netherlands)

Meijer Drees, N.C.

1989-01-01

The Devonian rock succession in the southern part of the District of Mackenzie consists of interbedded evaporites and carbonates, fossiliferous carbonates and shales. Inthe study areathe Devonian succession unconformably overlies LowerPaleozoic orPrecambrian strata and thins in a northeastward

Local variability in long-term care services: local autonomy, exogenous influences and policy spillovers.

Science.gov (United States)

Fernandez, José-Luis; Forder, Julien

2015-03-01

In many countries, public responsibility over the funding and provision of long-term care services is held at the local level. In such systems, long-term care provision is often characterised by significant local variability. Using a panel dataset of local authorities over the period 2002-2012, the paper investigates the underlying causes of variation in gross social care expenditure for older people in England. The analysis distinguishes between factors outside the direct control of policy makers, local preferences and local policy spillovers. The results indicate that local demand and supply factors, and to a much lesser extent local political preferences and spatial policy spillovers, explain a large majority of the observed variation in expenditure. Copyright © 2015 John Wiley & Sons, Ltd.

Analysis of Local Financial Management Transparency Based on Websites on Local Government in Java

Directory of Open Access Journals (Sweden)

Anissa Adriana

2018-03-01

Full Text Available The aim of this research is to analyze financial management transparency of local governments in Java using scoring and rating. The financial management transparency of the local governments is scored based on presentation of local financial information uploaded on each local government’s official website in Jawa in the fiscal years 2016.This research is a qualitative research with the object of research is all local government in Java. Data analysis in two levels, namely the transparency of local government financial management and identification of local government characteristics based on transparency of financial management. Data analysis in two levels, namely the transparency of local government financial management and identification of local government characteristics based on transparency of financial management. The results show that the Special Capital Region of Jakarta obtained the highest transparency index, at 58, 02% whereas Madiun Regency received the lowest transparency index, at 3, 40%. The average transparency index in Jawa for the fiscal years 2016 was still low, at only 19, 59%.The conclusion of this research is that Java regional governments consider the transparency of local financial management using less important websites because it is considered as a better thing not delivered to the public.

Local quantum thermal susceptibility

Science.gov (United States)

de Pasquale, Antonella; Rossini, Davide; Fazio, Rosario; Giovannetti, Vittorio

2016-09-01

Thermodynamics relies on the possibility to describe systems composed of a large number of constituents in terms of few macroscopic variables. Its foundations are rooted into the paradigm of statistical mechanics, where thermal properties originate from averaging procedures which smoothen out local details. While undoubtedly successful, elegant and formally correct, this approach carries over an operational problem, namely determining the precision at which such variables are inferred, when technical/practical limitations restrict our capabilities to local probing. Here we introduce the local quantum thermal susceptibility, a quantifier for the best achievable accuracy for temperature estimation via local measurements. Our method relies on basic concepts of quantum estimation theory, providing an operative strategy to address the local thermal response of arbitrary quantum systems at equilibrium. At low temperatures, it highlights the local distinguishability of the ground state from the excited sub-manifolds, thus providing a method to locate quantum phase transitions.

Afghanistan’s Local War: Building Local Defense Forces

Science.gov (United States)

2010-01-01

Afghanistan’s Local War: Building Local Defense Forces economic and other development conditions. As the Nobel Prize- winning economist Amartya Sen ...strengthen warlords 9 Amartya Sen , Development as Freedom, New York: Anchor Books, 2000, p. 11. Mitigating Risks 77 • weaken central government forces...Taliban Afghanistan, Bonn: Bonn International Center for Conversion, 2002. Sen , Amartya , Development as Freedom, New York: Anchor Books, 2000. Shahrani

Representative of local committee

International Nuclear Information System (INIS)

Barcelo, C.

2007-01-01

Carlos Barcelo, spoke about the involvement of local companies in the dismantling project. Local companies realised that they could not undertake the whole project, and informed ENRESA of the tasks in which they would be able to co-operate. On the whole, during the course of the 5-year project the local and regional firms were given more work than they had originally expected. Mr. Barcelo praised the good partnership that evolved between the local firms and the implementer. (author)

Locals Collection

Directory of Open Access Journals (Sweden)

Stephen Hastings-King

2010-03-01

Full Text Available A locals collection is a set of parameters that are used to delimit data-mining operations. This piece uses a collection of locals from around Essex Massachusetts to shape and delimit an interrogation of post-reality in contemporary America. It explores the notion of crisis, the possibility of a crisis of empire that may or may not emerge in a media-space that does not allow crisis of empire to be mentioned and relations this maybe-crisis to the various levels of economic dysfunction that have become evident since late 2008. But mostly this piece explores ways in which particular stories about particular people do and do not link/link to these larger-scale narratives. This is the first of a potential series of locals collections that will mine the American post-real.

Environmental isotopes in New Zealand hydrology ; 4. Oxygen isotope variations in subsurface waters of the Waimea Plains, Nelson

International Nuclear Information System (INIS)

Stewart, M.K.; Dicker, M.J.I.; Johnston, M.R.

1981-01-01

Oxygen isotope measurements of ground and surface waters of the Waimea Plains, Nelson, have been used to identify sources of water in aquifers beneath the plains. Major rivers flowing onto the plains are from higher-altitude catchments (maximum altitude 2000 m) and have delta O 18 approximately equal to -7.2%, whereas rainfall on the plains and adjacent low-altitude catchment streams have delta O 18 approximately equal to -6.2%. The delta O 18 measurements indicate that the 3 major aquifer units, the ''Lower Confined Aquifers'' and the ''Upper Confined Aquifers'' in the Hope Gravel (Late Pleistocene) and the ''Unconfined Aquifers'' in the Appleby Gravel (Holocene) are recharged from different sources. The ''Lower Confined Aquifers'' probably receive slow recharge in the south near Brightwater. The ''Upper Confined Aquifers'' are recharged, in the south, from the Wairoa River and locally in the north are connected with the unconfined aquifers. The ''Unconfined Aquifers'' are recharged from the Waimea River and, away from the river, from rainfall. Intermixing of water, via multiple screened wells, between the various aquifers is also indicated. (author). 5 refs., 5 figs., 1 tab

Geological Assessment of the Khor Kharfot Sediments, Western Dhofar Region, Sultanate of Oman

Directory of Open Access Journals (Sweden)

Iftikhar A. Abbasi

2016-11-01

Full Text Available Khor Kharfot is part of a coastal estuarine wetland system located in the western part of the Dhofar Governorate preserving a pristine ecosystem supporting a distinct vegetation and animal habitat. A sand barrier along the khor (local term for wetlands mouth controls the mixing of fresh and marine water in the enclosed lagoon. In order to understand the geological controls on the khor formation, a geological map of the khor barrier and inlet area is prepared. The khor is bounded by Cretaceous and Tertiary carbonate rock sequences which are cut by a number of faults. The khor mouth and barrier are comprised of late Holocene deposits divided into seven units including i beach sand, ii beach sand mixed with wadi gravels, iii scree and coastal dunes, iv lagoon, v soil and boulders, vi wadi gravels, and vii talus. The khor developed as an open estuary which changed to a barrier dominated lagoon due to falling fresh water supplies as a consequence of dwindling Khareef rains. The lagoon water is brackish due to the mixing of fresh and marine water and supports a distinct flora and fauna.

Local quantum thermal susceptibility

Science.gov (United States)

De Pasquale, Antonella; Rossini, Davide; Fazio, Rosario; Giovannetti, Vittorio

2016-01-01

Thermodynamics relies on the possibility to describe systems composed of a large number of constituents in terms of few macroscopic variables. Its foundations are rooted into the paradigm of statistical mechanics, where thermal properties originate from averaging procedures which smoothen out local details. While undoubtedly successful, elegant and formally correct, this approach carries over an operational problem, namely determining the precision at which such variables are inferred, when technical/practical limitations restrict our capabilities to local probing. Here we introduce the local quantum thermal susceptibility, a quantifier for the best achievable accuracy for temperature estimation via local measurements. Our method relies on basic concepts of quantum estimation theory, providing an operative strategy to address the local thermal response of arbitrary quantum systems at equilibrium. At low temperatures, it highlights the local distinguishability of the ground state from the excited sub-manifolds, thus providing a method to locate quantum phase transitions. PMID:27681458

The use of coal refuse as construction aggregates; Utilizacion de los Esteriles de Carbon como Aridos en Construccion

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-07-01

The objective of this project was to carry out a study which would allow us to determine the nature and properties of coal refuse for its possible use as construction aggregates: roadbeds concrete, bituminous meagres, etc. and to establish criteria of acceptability, placing, and quality control. Two types of refuse, considered to be representative, were chosen (one black and one red) and various trials were performed at a grinding and classifying plant for the obtention of granular materials. The results of these trials determined the most appropriate plant treatment for each type of refuse and established the margin of acceptability, criteria of acceptability, and quality control tests to be applied to the materials obtained from coal refuse for use as construction aggregates. Laboratory testing with both types of refuse mixed with binders (cement, emulsions) were carried out. At the same time, real scale tests, through the construction of concrete slabs in local roads and in trial areas, using the proportions of aggregates and cement that are customary in the area, and also by varying the cement content, substituting it for airborne ash from the thermal La Pereda power station were also performed. From the results obtained, it can be deduced that coal refuse can be used as granular material for roadbeds in different ways: stabilised as gravel-cement, in the form of gravel emulsion, as gravel slag, or by itself. As far as its use in concrete manufacture, it is limited to marginal works. With regard to its decorative use in gardening, it is being used in various town halls in Asturias and Cantabria. (Author)

Paleotsunamis in Eastern Taiwan

Science.gov (United States)

Yen, Jiun-Yee; Yu, Neng-Ti; Hirakawa, Kazuomi; Chyi, Shyh-Jeng; Huang, Shao-Yi

2017-04-01

Although Taiwan is located in the active collision zone between Eurasian and the Philippine Sea plate with very high seismicity in and surrounding the island, and supposedly highly susceptible to tsunami hazard. However, there is no record of tsunami hazard in the past one hundred years, and only very few historical records show some possible extreme event occurred. Therefore study of tsunami was scarce in Taiwan. Although historical records do show possible tsunami events, the records were too sparse and incomplete to confidently reconstruct the paleotsunami events. In the past few years, numerical simulations based on possible tsunami-genic zones near Taiwan show that the island could be affected by the correctly directed tsunami. Nevertheless, there is no detail, scientific research of paleotsunami records yet in Taiwan. Our field survey in eastern Taiwan (facing the western Pacific Ocean) along the coast uncovered several outcrops contain gravels embedded in well-developed soil layers. The rounded meta-sandstone gravels are clearly beach-origin and were brought to their current location upon extreme wave events, which is composed of either volcanic-clastic deposits from nearby hills or organic soil layers formed locally. Our investigation indicates that there are at least 3 events in the northern half of eastern Taiwan and at least 2 events in southern part of eastern Taiwan. Although these outcrops are next to the shoreline and Taiwan is susceptible from typhoons, these gravels could be farther away from the beach at the time of their deposition due to current high retreat rate of the sea cliff. Further investigations are needed to delineate possible sources of tsunamis that caused the deposits.

Characterization of aquifer heterogeneity in a complex fluvial hydrogeologic system to evaluate migration in ground water

International Nuclear Information System (INIS)

Baker, F.G.; Pavlik, H.F.

1990-01-01

The hydrogeology and extent of ground water contamination were characterized at a site in northern California. Wood preserving compounds, primarily pentachlorophenol (PCP) and creosote, have been detected in the soil and ground water. A plume of dissolved PCP up to 1.5 miles long has been identified south of the plant. The aquifer consists of a complex multizonal system of permeable gravels and sands composed of units from four geologic formations deposited by the ancestral Feather River. Fluvial channel gravels form the principal aquifer zones and contain overbank clay and silt deposits which locally form clay lenses or more continuous aquitards. The geometric mean horizontal hydraulic conductivities for channel gravels range between 120 to 530 feet/day. Mean vertical aquitard hydraulic conductivity is 0.07 feet/day. Ground water flow is generally southward with a velocity ranging from 470 to 1000 feet/year. The spatial distribution of dissolved PCP in the aquifer documents the interactions between major permeable zones. Hydrostratigraphic evidence pointing to the separation of aquifer zones is supported by the major ion chemistry of ground water. The sodium and calcium-magnesium bicarbonate-rich water present in the upper aquifer zones is significantly different in chemical composition from the predominantly sodium chloride-rich water present in the deeper permeable zone. This indicates that hydrodynamic separation exists between the upper and lower zones of the aquifer, limiting the vertical movement of the PCP plume. A numerical ground water model, based on this conceptual hydrogeologic model, was developed to evaluate groundwater transport pathways and for use in the design of a ground water extraction and treatment system. (9 refs., 7 figs., tab.)

Treatment of locally advanced/locally recurrent breast cancer and inflammatory breast cancer

International Nuclear Information System (INIS)

Murakami, Masao

2000-01-01

This paper summarizes the treatment of locally advanced breast cancer, inflammatory breast cancer, and locally recurrent breast cancer. A multidisciplinary approach considering subclinical distant metastases is needed to treat these types of breast cancer. Subclinical distant metastasis is observed in about 80% of case of locally advanced cancer, and treatment of subclinical distant metastases, e.g., by endocrinotherapy and chemotherapy, is therefore essential to improving the prognosis. The standard therapy for unresectable locally advanced breast cancer consists of induction chemotherapy with anthracyclines and local treatment with mastectomy or irradiation. Previous reports have stated that induction chemotherapy was effective in 60-80% of the primary lesions or lymph node metastasis, and the CR rates were in the 10-20% range. Combination therapy with induction chemotherapy clearly improved the outcome over local treatment alone. The usual irradiation dose is 50 to 60 Gy/5 to 7 weeks to the whole breast or the thoracic wall. Boost irradiation at a dose of 10 to 25 Gy is performed in unresectable cases. The boost irradiation dose to the lymph node area is usually 45 to 50 Gy/5 to 6 weeks in cases without gross lesions and 10 to 15 Gy in cases with gross lesions. Combination therapy consisting of conservative pectoral mastectomy and postoperative adjuvant chemo- endocrino-therapy (i.e., adjuvant therapy) has become the standard regimen for treating resectable locally advanced breast cancer, because it significantly improves the recurrence rate and survival rate compared to local treatment alone. Some clinical have studies indicated that neoadjuvant therapy (i.e., induction chemotherapy + surgery/radiation therapy) is comparable or superior to adjuvant therapy in terms of improving the prognosis. However, the efficacy and most appropriate method of breast-conserving therapy after induction chemotherapy are still unclear. More clinical trials are needed. It has been

Effects of roads on habitat quality for bears in the southern Appalachians: A long-term study

Science.gov (United States)

Reynolds-Hogland, M. J.; Mitchell, M.S.

2007-01-01

We tested the hypothesis that gravel roads, not paved roads, had the largest negative effect on habitat quality for a population of American black bears (Ursus americanus) that lived in a protected area, where vehicle collision was a relatively minimal source of mortality. We also evaluated whether road use by bears differed by sex or age and whether annual variation in hard mast productivity affected the way bears used areas near roads. In addition, we tested previous findings regarding the spatial extent to which roads affected bear behavior negatively. Using summer and fall home ranges for 118 black bears living in the Pisgah Bear Sanctuary in western North Carolina during 1981-2001, we estimated both home-range-scale (2nd-order) and within-home-range-scale (3rd-order) selection for areas within 250, 500, 800, and 1,600 m of paved and gravel roads. All bears avoided areas near gravel roads more than they avoided areas near paved roads during summer and fall for 2nd-order selection and during summer for 3rd-order selection. During fall, only adult females avoided areas near gravel roads more than they avoided areas near paved roads for 3rd-order selection. We found a positive relationship between use of roads by adults and annual variability in hard mast productivity. Overall, bears avoided areas within 800 m of gravel roads. Future research should determine whether avoidance of gravel roads by bears affects bear survival. ?? 2007 American Society of Mammalogists.

Quantification of local morphodynamics and local GTPase activity by edge evolution tracking.

Directory of Open Access Journals (Sweden)

Yuki Tsukada

2008-11-01

Full Text Available Advances in time-lapse fluorescence microscopy have enabled us to directly observe dynamic cellular phenomena. Although the techniques themselves have promoted the understanding of dynamic cellular functions, the vast number of images acquired has generated a need for automated processing tools to extract statistical information. A problem underlying the analysis of time-lapse cell images is the lack of rigorous methods to extract morphodynamic properties. Here, we propose an algorithm called edge evolution tracking (EET to quantify the relationship between local morphological changes and local fluorescence intensities around a cell edge using time-lapse microscopy images. This algorithm enables us to trace the local edge extension and contraction by defining subdivided edges and their corresponding positions in successive frames. Thus, this algorithm enables the investigation of cross-correlations between local morphological changes and local intensity of fluorescent signals by considering the time shifts. By applying EET to fluorescence resonance energy transfer images of the Rho-family GTPases Rac1, Cdc42, and RhoA, we examined the cross-correlation between the local area difference and GTPase activity. The calculated correlations changed with time-shifts as expected, but surprisingly, the peak of the correlation coefficients appeared with a 6-8 min time shift of morphological changes and preceded the Rac1 or Cdc42 activities. Our method enables the quantification of the dynamics of local morphological change and local protein activity and statistical investigation of the relationship between them by considering time shifts in the relationship. Thus, this algorithm extends the value of time-lapse imaging data to better understand dynamics of cellular function.

Dual entanglement measures based on no local cloning and no local deleting

International Nuclear Information System (INIS)

Horodecki, Michal; Sen, Aditi; Sen, Ujjwal

2004-01-01

The impossibility of cloning and deleting of unknown states constitute important restrictions on processing of information in the quantum world. On the other hand, a known quantum state can always be cloned or deleted. However, if we restrict the class of allowed operations, there will arise restrictions on the ability of cloning and deleting machines. We have shown that cloning and deleting of known states is in general not possible by local operations. This impossibility hints at quantum correlation in the state. We propose dual measures of quantum correlation based on the dual restrictions of no local cloning and no local deleting. The measures are relative entropy distances of the desired states in a (generally impossible) perfect local cloning or local deleting process from the best approximate state that is actually obtained by imperfect local cloning or deleting machines. Just like the dual measures of entanglement cost and distillable entanglement, the proposed measures are based on important processes in quantum information. We discuss their properties. For the case of pure states, estimations of these two measures are also provided. Interestingly, the entanglement of cloning for a maximally entangled state of two two-level systems is not unity

Geohydrology of the valley-fill aquifer in the Endicott-Johnson City area, Broome County, New York

Science.gov (United States)

Holecek, Thomas J.; Randall, A.D.; Belli, J.L.; Allen, R.V.

1982-01-01

This report is the tenth in a series of 11 map sets depicting geohydrologic conditions in selected aquifers in upstate New York. Geohydrologic data are compiled on five maps at 1:24,000 scale. Together, the maps provide a comprehensive overview of a major valley-fill aquifer in southwestern Broome County. The maps include surficial geology, geologic sections, aquifer thickness, water-infiltration potential of soil zone, potentiometric-surface altitude, and land use. The valley-fill deposits consist of alluvial silt and sand, glacial outwash (sand and gravel), ice-contact sand and gravel, till, and lacustrine silt and clay. The sand and gravel beds have relatively high permeabilities whereas the till, silt, and clay deposits have relatively low permeabilities. Water-table conditions are found in unconfined sand and gravel, whereas artesian conditions prevail within sand and gravel confined by silty deposits. Recharge occurs over the entire surface of the aquifer, due to permeable land-surface conditions, but is greatest along the margin of the valley, where runoff from the hillsides is concentrated, and near streams. The use of land overlying the aquifer is predominantly commercial and residential with lesser amounts of agricultural and industrial uses. (USGS)

Geohydrology of the valley-fill aquifer in the South Fallsburgh-Woodbourne area, Sullivan County, New York

Science.gov (United States)

Anderson, H.R.; Dineen, R.J.; Stelz, W.G.; Belli, J.L.

1982-01-01

This report is the ninth in a series of map sets depicting geohydrologic conditions in selected aquifers in upstate New York. Geohydrologic data are compiled on six maps at 1:24,000 scale. Together the maps provide a comprehensive overview of a major valley-fill aquifer in southeastern Sullivan County. The maps include surficial geology, geologic sections, aquifer thickness, water-infiltration potential of soil zone, potentiometric surface elevations, well yields, and land use. The valley-fill deposits consist of alluvial silt and sand, glacial outwash (sand and gravel), ice-contact sand and gravel, till, and lacustrine silt and clay. The sand and gravel beds have relatively high permeabilities whereas the till, silt, and clay deposits have relatively low permeabilities. Water-table conditions prevail in unconfined sand and gravel whereas artesian conditions prevail within sand and gravel confined by silty deposits. The aquifer is recharged throughout, where the land surface is most permeable and is greatest along the margin of the valley, where runoff from the hillsides is concentrated. The use of land overlying the aquifer is predominantly commercial, agricultural, and residential with lesser industrial uses. (USGS)

Geohydrology of the valley-fill aquifer in the Jamestown area, Chautauqua County, New York

Science.gov (United States)

Anderson, H.R.; Stelz, W.G.; Belli, J.L.; Allen, R.V.

1982-01-01

This report is the sixth in a series of 11 map sets depicting geohydrologic conditions in selected aquifers in upstate New York. Geohydrologic data are compiled on six maps at 1:24,000 scale. Together, the maps provide a comprehensive overview of a major valley-fill aquifer in southeastern Chautauqua County. The maps include surficial geology, geologic sections, water-infiltration potential of soil zone, aquifer thickness, potentiometric-surface elevations and land use. The valley-fill deposits consist of alluvial silt and sand, glacial-outwash (sand and gravel), ice-contact sand and gravel, till, and lacustrine silt and clay. The sand and gravel beds have relatively high permeabilities whereas the till, silt and clay deposits have relatively low permeabilities. Water-table conditions prevail in u nconfined sand and gravel beds along the valley margin. Artesian conditions prevail in confined sand and gravel buried under silt and clay in the middle of the valley. Recharge occurs mainly along the margin of the valley, where the land surface is highly permeable and runoff from the hillsides is concentrated. The use of land overlying the aquifer is predominantly agricultural and residential with lesser amounts of commercial and industrial uses. (USGS)

Fluvial sediments characterization of Hornád river in its chosen parts (preliminary study

Directory of Open Access Journals (Sweden)

Stela Hanigovská

2008-12-01

Full Text Available Knowledge of main river sedimentary characteristics is very important source of information for next study or potentialcommercial usage of fluvial sediments. In paper is shown characterization of sediment distribution in chosen part of the river Hornád.Three main facial types were studied and described – gravel, sand and clay. Model created in this study shows that Hornád is a riverwith predominant gravel transport. This model also shows a sufficient amount of gravel for commercial use in some parts of the river.

On the local equilibrium condition

International Nuclear Information System (INIS)

Hessling, H.

1994-11-01

A physical system is in local equilibrium if it cannot be distinguished from a global equilibrium by ''infinitesimally localized measurements''. This should be a natural characterization of local equilibrium, but the problem is to give a precise meaning to the qualitative phrase ''infinitesimally localized measurements''. A solution is suggested in form of a Local Equilibrium Condition (LEC), which can be applied to linear relativistic quantum field theories but not directly to selfinteracting quantum fields. The concept of local temperature resulting from LEC is compared to an old approach to local temperature based on the principle of maximal entropy. It is shown that the principle of maximal entropy does not always lead to physical states if it is applied to relativistic quantum field theories. (orig.)

The generally covariant locality principle - a new paradigm for local quantum field theory

International Nuclear Information System (INIS)

Brunetti, R.; Fredenhagen, K.; Verch, R.

2002-05-01

A new approach to the model-independent description of quantum field theories will be introduced in the present work. The main feature of this new approach is to incorporate in a local sense the principle of general covariance of general relativity, thus giving rise to the concept of a locally covariant quantum field theory. Such locally covariant quantum field theories will be described mathematically in terms of covariant functors between the categories, on one side, of globally hyperbolic spacetimes with isometric embeddings as morphisms and, on the other side, of *-algebras with unital injective *-endomorphisms as morphisms. Moreover, locally covariant quantum fields can be described in this framework as natural transformations between certain functors. The usual Haag-Kastler framework of nets of operator-algebras over a fixed spacetime background-manifold, together with covariant automorphic actions of the isometry-group of the background spacetime, can be re-gained from this new approach as a special case. Examples of this new approach are also outlined. In case that a locally covariant quantum field theory obeys the time-slice axiom, one can naturally associate to it certain automorphic actions, called ''relative Cauchy-evolutions'', which describe the dynamical reaction of the quantum field theory to a local change of spacetime background metrics. The functional derivative of a relative Cauchy-evolution with respect to the spacetime metric is found to be a divergence-free quantity which has, as will be demonstrated in an example, the significance of an energy-momentum tensor for the locally covariant quantum field theory. Furthermore, we discuss the functorial properties of state spaces of locally covariant quantum field theories that entail the validity of the principle of local definiteness. (orig.)

LOCAL ORGANIZING COMMITTEE

Indian Academy of Sciences (India)

Prof. B. B. P. Gupta

INDIAN ACADEMY OF SCIENCES. Bengaluru. 83rd ANNUAL MEETING. 3–5 November 2017, NEHU, Shillong. LOCAL ORGANIZING COMMITTEE. Local Organizing Committee. 1. Prof. S. K. Srivastava. Chairman. Vice-Chancellor, NEHU, Shillong. 2. Prof. B. B. P. Gupta. Organising Secretary. Department of Zoology ...

Warm season performance of horizontal subsurface flow constructed ...

African Journals Online (AJOL)

user

2013-06-14

Jun 14, 2013 ... degradation and population risk of diseases particularly ..... 5G: gravel substrate with a HRT of 5 days; 5S: sand substrate with a HRT of 5 days; 10G: gravel substrate with a .... American Public Health Association; American.

Chen-Nester-Tung quasi-local energy and Wang-Yau quasi-local mass

Science.gov (United States)

Liu, Jian-Liang; Yu, Chengjie

2017-10-01

In this paper, we show that the Chen-Nester-Tung (CNT) quasi-local energy with 4D isometric matching references is closely related to the Wang-Yau (WY) quasi-local energy. As a particular example, we compute the second variation of the CNT quasi-local energy for axially symmetric Kerr-like spacetimes with axially symmetric embeddings at the obvious critical point (0 , 0) and find that it is a saddle critical point in most of the cases. Also, as a byproduct, we generalize a previous result about the coincidence of the CNT quasi-local energy and Brown-York mass for axially symmetric Kerr-like spacetimes by Tam and the first author Liu and Tam (2016) to general spacetimes.

Latest Pannonian and Quaternary evolution at the transition between Eastern Alps and Pannonian Basin: new insights from geophysical, sedimentological and geochronological data

Science.gov (United States)

Zámolyi, A.; Salcher, B.; Draganits, E.; Exner, U.; Wagreich, M.; Gier, S.; Fiebig, M.; Lomax, J.; Surányi, G.; Diel, M.; Zámolyi, F.

2017-07-01

The transition zone between Eastern Alps and Pannonian Basin is a key area for the investigation of the interplay between regional uplift, local tectonic subsidence and depositional environment. Our study area, the western margin of the Little Hungarian Plain, is characterized by gentle hills, plateaus and depressions, of which several are filled by lakes—including one of Austria's largest and shallowest lakes, Lake Neusiedl. Geological investigation is hampered by the scarcity of outcrops, and thus direct observation of sedimentological or structural features is difficult. Despite a long research history in the area, a consistent landscape evolution model considering all relevant constraints is lacking so far. In this study, we apply multidisciplinary methods to decipher the complex tectonic and fluvial depositional evolution of the region. Local data from shallow-lake drilling and seismic investigation are combined with regional data from industrial seismics and core data to gain new insights into the latest Pannonian (Late Miocene) and Quaternary evolution. Shallow-lake seismic data show the erosionally truncated Pannonian sediments dipping and thickening toward southeast, toward the modern depocenter of the Little Hungarian Plain. Overlying Quaternary fluvial sediments show a very similar thickening trend except for the area on the plateau north of the lake indicating ongoing subsidence in major parts of the basin. Drill cores from locations along the lake seismic lines were analyzed concerning their age, mineralogy and heavy minerals and compared with outcrop samples from the surrounding plains and the plateau to derive indications on sediment provenance. A key observation is the apparent lack of a significant gravel layer on top of the tilted Pannonian sediments beneath Lake Neusiedl. Small-scale faults can be observed in the lake seismic sections along with key sedimentary features. Significant differences of the current elevation of the top Pannonian

Does local government have capacity for enabling local economic development? Lessons from Jamaica

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Eris D Schoburgh

2014-07-01

Full Text Available Implementation of the Caribbean Local Economic Development Project (CARILED1began in 2012 in seven countries for a duration of six years, to support sustainable economic growth in the region. CARILED has introduced the idea of local economic development (LED to the ‘development’ debate in the region but has also brought the organisational capacity of local government, and local government’s role as ‘facilitator’ of LED,to the fore. This paper assesses organizational behaviour and capability in local government in Jamaica to determine the state of readiness for a developmental role. The paper draws on two sets of research data to aid its analysis–a capacity audit (CAPAUD conducted in 2010 and an organisational analysis (OAcommissioned by the Ministry of Local Government in 2010, both of which targeted a sample of local authorities in Jamaica. The study found that when assessed against established criteria for an LED organisation, ie: research and information provision; marketing and coordination; learning and innovation; and leadership - local government’s institutional and organisational capacity for development is unevenly distributed. For instance, local leaders understood organisational purpose but efforts to give effect to this appeared undeveloped, sporadic and uni-directional. It was also evident that participatory strategies are used to gain information from communities but these were often devoid of systematic research methodologies rendering formal community impact on local planning negligent. Finally there is strong potential for the kind of administrative leadership required by a developmental local government to evolve,indicated by the quality of training, quantum of managerial/supervisory staff, and stability of staff establishment. However, this potential is threatened by the deficiencies in the non-traditional functional areas that are strategic to the organisation’s effectiveness as a ‘facilitator’ of LED, ie

Desempleo y justicia local

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Elster, Jon

2003-04-01

Full Text Available In this paper Jon Elster presents a set of criteria of local justice that regulate dismissals. In situations where work is limited and companies adopt means of employment redundancy, the decision of dismissing certain workers —when this one tries not to be arbitrary— can be based on local criteria of fairness like merit, efficiency, age or other analysed in this work. So, after defining the concept of local justice and presenting some examples, the paper focuses on the importance of the work to organize and structure the life of people. Unemployment has serious consequences for the persons who suffer it and the author advises that it is necessary to subordinate dismissals to criteria of local justice.

En este artículo se presentan una serie de criterios de justicia local para regular los despidos. En situaciones en las que el trabajo es escaso y las empresas adoptan medidas de regulación de empleo, la decisión de despedir a unos trabajadores o a otros se puede basar, cuando se intenta que no sea arbitraria, en criterios locales de equidad como el mérito, la eficacia, la edad u otros que se analizan en este trabajo. Así, tras definir el concepto de justicia local y presentar algunos ejemplos, el artículo se centra en la importancia del trabajo para organizar y estructurar la vida de la gente. Las graves consecuencias que tiene, por ello, el desempleo para quien lo sufre, aconseja que los despidos se sometan a criterios de justicia local.

Local Self-Government as an Architect of Coalitions for Local Development

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Anna Gąsior-Niemiec

2014-12-01

Full Text Available The paper addresses the new role played by local self-government units in Poland. Main factors that determine the public authorities’ capacity to become architects of coalitions for local development are identified. Coalitions are defined as partnerships linking and mobilizing stakeholders anchored in three sectors: public, economic and non-governmental. The coalition-making role of the public organs is investigated on the basis of Local Action Groups (LAGs, which are pro-developmental cross-sector organizations established in rural areas of the Podkarpackie (Sub-Carpathian Voivodesh ip, Poland. Findings are presented that draw on quantitative and qualitative results of the research project that investigated mechanisms involved in the operation of the cross-s ector coalitions. The dominant role of the public authorities in those coalitions is demonstrated. The Community-led Local Development model is referred to as the future framework for LAGs.

Groundwaters of Florence (Italy): Trace element distribution and vulnerability of the aquifers

Science.gov (United States)

Bencini, A.; Ercolanelli, R.; Sbaragli, A.; Verrucchi, C.

1993-11-01

Geochemical and hydrogeological research has been carried out on 109 wells in the alluvial plain of Florence, in order to evaluate conductivity and main chemistry of ground waters, the pattern of some possible pollutant chemical species (Fe, Mn, Cr, Cu, Pb, Zn, NO2, NO3), and the vulnerability of the aquifers. The plain is made up of Plio-Quaternary alluvial and lacustrine sediments for a maximum thickness of 600 m. Silts and clays, sometimes with lenses of sandy gravels, are dominant, while considerable deposits of sands, pebbles, and gravels occur along the course of the Arno river and its tributary streams, and represent the most important aquifer of the plain. The groundwaters analyzed belong to this aquifer or to the smaller ones, hosted in the gravel lenses. Most waters show conductivity values around 1000 1200 μS, and almost all of them have an alkaline-earth-bicarbonate chemical character; these features are consistent with the mainly calcareous lithology of the aquifers. In the western areas a higher salt content of the groundwaters is evident, probably related to the presence of industrial activities which use water desalinators. Heavy metal and NO2, NO3 analyses point out that no important pollution phenomena affect the groundwaters; all the mean values of the chemical considered species are below the maximum admissible concentration (MAC) fixed by the European Community for drinkable waters. Nevertheless, some anomalies of NO2, NO3, Fe, Mn, and Zn are present in the plain. Apart from Mn, which seems to be released by certain calcareous gravels, the other anomalies have a local influence, since they disappear even in the nearest wells. The most plausible causes can be recognized in losses of the sewage system (NO2=3 4 mg/t); use of nitrate compounds in agriculture (NO3=60 70 mg/l); oxidation of well pipes (Fe ≈ 20 mg/l; Zn ≈ 6 mg/l). As regards Cr, Cu, and Pb, all the observations are below the MAC; therefore, the median values of bacteria oxidation

Local anaesthetic toxicity

African Journals Online (AJOL)

Local anaesthetic toxicity has been known since the introduction of local anaesthetic drugs into anaesthetic practice more than a hundred ... was the first to think of cocaine as a narcotic. ..... anaesthetics act as Na+ channel-blocking agents, they slow down .... all neurons, leading to global CNS depression, slowing and.

Forests of the tropical eastern Andean flank during the middle Pleistocene

NARCIS (Netherlands)

Cárdenas, M.L.; Gosling, W.D.; Pennington, R.T.; Poole, I.; Sherlock, S.C.; Mothes, P.

2014-01-01

Inter-bedded volcanic and organic sediments from Erazo (Ecuador) indicate the presence of four different forest assemblages on the eastern Andean flank during the middle Pleistocene. Radiometric dates (40Ar-39Ar) obtained from the volcanic ash indicate that deposition occurred between 620,000 and

On the Approximate Solutions of Local Fractional Differential Equations with Local Fractional Operators

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Hossein Jafari

2016-04-01

Full Text Available In this paper, we consider the local fractional decomposition method, variational iteration method, and differential transform method for analytic treatment of linear and nonlinear local fractional differential equations, homogeneous or nonhomogeneous. The operators are taken in the local fractional sense. Some examples are given to demonstrate the simplicity and the efficiency of the presented methods.

PRESSURE EQUILIBRIUM BETWEEN THE LOCAL INTERSTELLAR CLOUDS AND THE LOCAL HOT BUBBLE

Energy Technology Data Exchange (ETDEWEB)

Snowden, S. L.; Chiao, M.; Collier, M. R.; Porter, F. S.; Thomas, N. E. [NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Cravens, T.; Robertson, I. P. [Department of Physics and Astronomy, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS 66045 (United States); Galeazzi, M.; Uprety, Y.; Ursino, E. [Department of Physics, University of Miami, 1320 Campo Sano Drive, Coral Gables, FL 33146 (United States); Koutroumpa, D. [Université Versailles St-Quentin, Sorbonne Universités, UPMC Univ. Paris 06, CNRS/INSU, LATMOS-IPSL, 11 Boulevard d' Alembert, F-78280 Guyancourt (France); Kuntz, K. D. [The Henry A. Rowland Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218 (United States); Lallement, R.; Puspitarini, L. [GEPI, Observatoire de Paris, CNRS UMR8111, Université Paris Diderot, 5 Place Jules Janssen, F-92190 Meudon (France); Lepri, S. T. [University of Michigan, 2455 Hayward Street, Ann Arbor, MI 48109 (United States); McCammon, D.; Morgan, K. [Department of Physics, University of Wisconsin, 1150 University Avenue, Madison, WI 53706 (United States); Walsh, B. M., E-mail: steven.l.snowden@nasa.gov [Space Sciences Laboratory, 7 Gauss Way, Berkeley, CA 94720 (United States)

2014-08-10

Three recent results related to the heliosphere and the local interstellar medium (ISM) have provided an improved insight into the distribution and conditions of material in the solar neighborhood. These are the measurement of the magnetic field outside of the heliosphere by Voyager 1, the improved mapping of the three-dimensional structure of neutral material surrounding the Local Cavity using extensive ISM absorption line and reddening data, and a sounding rocket flight which observed the heliospheric helium focusing cone in X-rays and provided a robust estimate of the contribution of solar wind charge exchange emission to the ROSAT All-Sky Survey 1/4 keV band data. Combining these disparate results, we show that the thermal pressure of the plasma in the Local Hot Bubble (LHB) is P/k = 10, 700 cm{sup –3} K. If the LHB is relatively free of a global magnetic field, it can easily be in pressure (thermal plus magnetic field) equilibrium with the local interstellar clouds, eliminating a long-standing discrepancy in models of the local ISM.

Sedimentary facies and evolution of the upper member of cretaceou Sunjiawan formation in Heishui area of western Liaoning

International Nuclear Information System (INIS)

Zhao Zhonghua; Xi Haiyin; Chen Debing; Wang Liming; Rao Minghui

2010-01-01

The upper member of Sunjiawan formation in Heishui area is mainly alluvial fan facies. From the macroscopic view, alluvial fan facies can be divided into three sub-facies of proximal end gravel braided plain, distal end gravel braided plain and pre-fan flood-plain and further into some micro-facies of debris flow, gravel braided channel, gravel dam, flood-fine and peat bog etc. The upper member of Sunjiawan formation could be divided into three sub-members. The first sub-member is retrograding dry land type fan sediment under drought-humid climate. The second sub-member is retrograding wet land type fan deposit under humid climate. Third sub-member is progradational wetland type fan sediments under humid climate. Sunjiawan formation in Heishui area experienced three evolutionary stages: the early retrograding dryland type fan deposition, the medium term retrograding wet land type fan deposition and the later progradational wetland type fan. (authors)

Natural radioactivity and associated radiation hazardous of main building materials in Yan'an, China

International Nuclear Information System (INIS)

Li Nan; Lu Xinwei; Yang Guang; Zhao Caifeng

2012-01-01

Background: With the rapidly economic development and urbanization in Yan'an city, more building materials were consumed in building construction. While the natural radioactivity level of building materials from Yan'an is limited in the literatures. Purpose: The main objective of this study is to determine the natural radioactivity level and to analyze the associated radiation hazards of building materials in Yan'an. Methods: The specific activities of natural radionuclides 226 Ra, 232 Th and 40 K in various building materials from Yan'an city were determined using low-background gamma-ray spectrometry, and their radiation hazards were evaluated according to the standard methods. Results: The results show that the specific activities of 226 Ra, 232 Th and 40 K in the building materials are 9.4-73.1, 11.5-86.9 and 258.9-1055.1 Bq/kg, respectively. The activities of 226 Ra and 232 Th, except for sand and gravel aggregate, in all other building materials are higher than the corresponding means of local soil, and the activities of 40 K in hollow brick, red-clay brick, sand and gravel aggregate exceed the means of 40 K in soil. However, the values of internal exposure index, external exposure index and gamma radiation index in all investigated building materials are less than 1. Conclusions: The radiation levels of all analyzed building materials are within the national safety standard, which indicates that all analyzed building materials can be used anywhere and they can't cause radiation hazard to the local residents. (authors)

Optimization of typical diffuse herbicide pollution control by soil amendment configurations under four levels of rainfall intensities.

Science.gov (United States)

Ouyang, Wei; Huang, Weijia; Wei, Peng; Hao, Fanghua; Yu, Yongyong

2016-06-15

Herbicides are a main source of agricultural diffuse pollution due to their wide application in tillage practices. The aim of this study is to optimize the control efficiency of the herbicide atrazine with the aid of modified soil amendments. The soil amendments were composed of a combination of biochar and gravel. The biochar was created from corn straw with a catalytic pyrolysis of ammonium dihydrogen phosphate. The leaching experiments under four rainfall conditions were measured for the following designs: raw soil, soil amended with gravel, biochar individually and together with gravel. The control efficiency of each design was also identified. With the designed equipment, the atrazine content in the contaminant load layer, gravel substrate layer, biochar amendment layer and soil layer was measured under four types of rainfall intensities (1.25 mm/h, 2.50 mm/h, 5.00 mm/h and 10.00 mm/h). Furthermore, the vertical distribution of atrazine in the soil sections was also monitored. The results showed that the herbicide leaching load increased under the highest rainfall intensity in all designs. The soil with the combination of gravel and biochar provided the highest control efficiency of 87.85% on atrazine when the additional proportion of biochar was 3.0%. The performance assessment under the four kinds of rainfall intensity conditions provided the guideline for the soil amendment configuration. The combination of gravel and biochar is recommended as an efficient method for controlling diffuse herbicide pollution. Copyright © 2016 Elsevier Ltd. All rights reserved.

Local government and climate policy

International Nuclear Information System (INIS)

Burger, H.; Menkveld, M.; Coenen, F.H.J.M.

2000-01-01

Local government in the Netherlands could play a greater role than they currently do in reducing greenhouse gas emissions in the country. This fact formed the motivation for initiating the research project on Local Government and Climate Policy. Many local climate options are known in theory. Options for reduction that lie within the sphere of influence of Dutch local government are, for example, sustainable building or encouraging the utilisation of sustainable energy. But actual practice turns out to be rather refractory. If such options are to be implemented, then one has to overcome institutional barriers, such as the co-operation between different departments in the same local authority. The objective of this research is to improve the contribution that local government makes to climate policy

Longitudinally Vibrating Elastic Rods with Locally and Non-Locally Reacting Viscous Dampers

Directory of Open Access Journals (Sweden)

Şefaatdin Yüksel

2005-01-01

Full Text Available Eigencharacteristics of a longitudinally vibrating elastic rod with locally and non-locally reacting damping are analyzed. The rod is considered as a continuous system and complex eigenfrequencies are determined as solution of a characteristic equation. The variation of the damping ratios with respect to damper locations and damping coefficients for the first four eigenfrequencies are obtained. It is shown that at any mode of locally or non-locally damped elastic rod, the variation of damping ratio with damper location is linearly proportional to absolute value of the mode shape of undamped system. It is seen that the increasing damping coefficient does not always increase the damping ratio and there are optimal values for the damping ratio. Optimal values for external damping coefficients of viscous dampers and locations of the dampers are presented.

Headwater Stream Management Dichotomies: Local Amphibian Habitat vs. Downstream Fish Habitat

Science.gov (United States)

Jackson, C. R.

2002-12-01

Small headwater streams in mountainous areas of the Pacific Northwest often do not harbor fish populations because of low water depth and high gradients. Rather, these streams provide habitat for dense assemblages of stream-dwelling amphibians. A variety of management goals have been suggested for such streams such as encouraging large woody debris recruitment to assist in sediment trapping and valley floor formation, encouraging large woody debris recruitment to provide downstream wood when debris flows occur, providing continuous linear stream buffers within forest harvest areas to provide shade and bank stability, etc. A basic problem with analying the geomorphic or biotic benefits of any of these strategies is the lack of explicit management goals for such streams. Should managers strive to optimize downstream fish habitat, local amphibian habitat, or both? Through observational data and theoretical considerations, it will be shown that these biotic goals will lead to very different geomorphic management recommendations. For instance, woody debris greater than 60 cm diameter may assist in valley floor development, but it is likely to create subsurface channel flow of unknown value to amphibians. Trapping and retention of fine sediments within headwater streams may improve downstream spawning gravels, but degrades stream-dwelling amphibian habitat. In response to the need for descriptive information on habitat and channel morphology specific to small, non-fish-bearing streams in the Pacific Northwest, morphologies and wood frequencies in forty-two first- and second-order forested streams less than four meters wide were surveyed. Frequencies and size distributions of woody debris were compared between small streams and larger fish-bearing streams as well as between second-growth and virgin timber streams. Statistical models were developed to explore dominant factors affecting channel morphology and habitat. Findings suggest geomorphological relationships

Radioguided occult lesion localization versus wire-guided localization for non-palpable breast lesions: randomized controlled trial

International Nuclear Information System (INIS)

Ocal, Koray; Dag, Ahmet; Turkmenoglu, Ozgur; Yucel, Erdem; Gunay, Emel Ceylan; Duce, Meltem Nass

2011-01-01

Aim: this prospective randomized clinical study was conducted to compare radioguided occult lesion localization (ROLL) with wire-guided localization to evaluate optimum localization techniques for non-palpable breast lesions. Methods: a total of 108 patients who were undergoing an excisional biopsy for non-palpable breast lesions requiring pathologic diagnosis were randomly assigned to the ROLL group (n 56) and wire-guided localization group (n 52). In the study, patients' characteristics, radiological abnormalities, radiological technique of localization, localization time, operation time, weight of the excised specimen, clearance margins, pathological diagnosis and perioperative complications were assessed. Results: there were no differences between the two groups in terms of age, radiological abnormalities and localization technique (p = non-significant for all). ROLL techniques resulted in 100% retrieval of the lesions; for the wire-guided localization technique, 98%. Both localization time and operation time were significantly reduced with the ROLL technique (p = significant for all). The weight of the specimen was significantly lower in the ROLL group than in the wire-guided localization group (p = significant). The overall complication rate and pathological diagnosis were similar for both groups (p = non-significant for all). Clear margins were achieved in 91% of ROLL patients and in 53% of wire-guided localization patients, and the difference was significant. Conclusions: the present study indicated that the ROLL technique is as effective as wire-guided localization for the excision of non-palpable breast lesions. In addition, ROLL improved the outcomes by reducing localization and operation time, preventing healthy tissue excision and achieving clearer margins. (author)

Radioguided occult lesion localization versus wire-guided localization for non-palpable breast lesions: randomized controlled trial

Energy Technology Data Exchange (ETDEWEB)

Ocal, Koray; Dag, Ahmet; Turkmenoglu, Ozgur; Yucel, Erdem [Mersin University (Turkey). Medical Faculty. Dept. of General Surgery; Gunay, Emel Ceylan [Mersin University (Turkey). Medical Faculty. Dept. of Nuclear Medicine; Duce, Meltem Nass [Mersin University (Turkey). Medical Faculty. Dept. of Radiology

2011-07-01

Aim: this prospective randomized clinical study was conducted to compare radioguided occult lesion localization (ROLL) with wire-guided localization to evaluate optimum localization techniques for non-palpable breast lesions. Methods: a total of 108 patients who were undergoing an excisional biopsy for non-palpable breast lesions requiring pathologic diagnosis were randomly assigned to the ROLL group (n 56) and wire-guided localization group (n 52). In the study, patients' characteristics, radiological abnormalities, radiological technique of localization, localization time, operation time, weight of the excised specimen, clearance margins, pathological diagnosis and perioperative complications were assessed. Results: there were no differences between the two groups in terms of age, radiological abnormalities and localization technique (p = non-significant for all). ROLL techniques resulted in 100% retrieval of the lesions; for the wire-guided localization technique, 98%. Both localization time and operation time were significantly reduced with the ROLL technique (p = significant for all). The weight of the specimen was significantly lower in the ROLL group than in the wire-guided localization group (p = significant). The overall complication rate and pathological diagnosis were similar for both groups (p = non-significant for all). Clear margins were achieved in 91% of ROLL patients and in 53% of wire-guided localization patients, and the difference was significant. Conclusions: the present study indicated that the ROLL technique is as effective as wire-guided localization for the excision of non-palpable breast lesions. In addition, ROLL improved the outcomes by reducing localization and operation time, preventing healthy tissue excision and achieving clearer margins. (author)

Local Fractional Adomian Decomposition and Function Decomposition Methods for Laplace Equation within Local Fractional Operators

Directory of Open Access Journals (Sweden)

Sheng-Ping Yan

2014-01-01

Full Text Available We perform a comparison between the local fractional Adomian decomposition and local fractional function decomposition methods applied to the Laplace equation. The operators are taken in the local sense. The results illustrate the significant features of the two methods which are both very effective and straightforward for solving the differential equations with local fractional derivative.

The correlation of local deformation and stress-assisted local phase transformations in MMC foams

Energy Technology Data Exchange (ETDEWEB)

Berek, H., E-mail: harry.berek@ikgb.tu-freiberg.de [TU Bergakademie Freiberg, Agricolastraße 17, D-09599 Freiberg (Germany); Ballaschk, U.; Aneziris, C.G. [TU Bergakademie Freiberg, Agricolastraße 17, D-09599 Freiberg (Germany); Losch, K.; Schladitz, K. [Fraunhofer ITWM, Fraunhoferplatz 1, D-67663 Kaiserslautern (Germany)

2015-09-15

Cellular structures are of growing interest for industry, and are of particular importance for lightweight applications. In this paper, a special case of metal matrix composite foams (MMCs) is investigated. The investigated foams are composed of austenitic steel exhibiting transformation induced plasticity (TRIP) and magnesia partially stabilized zirconia (Mg-PSZ). Both components exhibit martensitic phase transformation during deformation, thus generating the potential for improved mechanical properties such as strength, ductility, and energy absorption capability. The aim of these investigations was to show that stress-assisted phase transformations within the ceramic reinforcement correspond to strong local deformation, and to determine whether they can trigger martensitic phase transformations in the steel matrix. To this end, in situ interrupted compression experiments were performed in an X-ray computed tomography device (XCT). By using a recently developed registration algorithm, local deformation could be calculated and regions of interest could be defined. Corresponding cross sections were prepared and used to analyze the local phase composition by electron backscatter diffraction (EBSD). The results show a strong correlation between local deformation and phase transformation. - Graphical abstract: Display Omitted - Highlights: • In situ compressive deformation on MMC foams was performed in an XCT. • Local deformation fields and their gradient amplitudes were estimated. • Cross sections were manufactured containing defined regions of interest. • Local EBSD phase analysis was performed. • Local deformation and local phase transformation are correlated.

The correlation of local deformation and stress-assisted local phase transformations in MMC foams

International Nuclear Information System (INIS)

Berek, H.; Ballaschk, U.; Aneziris, C.G.; Losch, K.; Schladitz, K.

2015-01-01

Cellular structures are of growing interest for industry, and are of particular importance for lightweight applications. In this paper, a special case of metal matrix composite foams (MMCs) is investigated. The investigated foams are composed of austenitic steel exhibiting transformation induced plasticity (TRIP) and magnesia partially stabilized zirconia (Mg-PSZ). Both components exhibit martensitic phase transformation during deformation, thus generating the potential for improved mechanical properties such as strength, ductility, and energy absorption capability. The aim of these investigations was to show that stress-assisted phase transformations within the ceramic reinforcement correspond to strong local deformation, and to determine whether they can trigger martensitic phase transformations in the steel matrix. To this end, in situ interrupted compression experiments were performed in an X-ray computed tomography device (XCT). By using a recently developed registration algorithm, local deformation could be calculated and regions of interest could be defined. Corresponding cross sections were prepared and used to analyze the local phase composition by electron backscatter diffraction (EBSD). The results show a strong correlation between local deformation and phase transformation. - Graphical abstract: Display Omitted - Highlights: • In situ compressive deformation on MMC foams was performed in an XCT. • Local deformation fields and their gradient amplitudes were estimated. • Cross sections were manufactured containing defined regions of interest. • Local EBSD phase analysis was performed. • Local deformation and local phase transformation are correlated

Hot mix asphalt (HMA) characterization for the 2002 AASHTO design guide.

Science.gov (United States)

2008-09-30

The two study objectives were to conduct dynamic modulus and APA rutting tests of selected Mississippi HMA mixtures. A total of twenty-five mixtures were tested including aggregate combinations of gravel and gravel/limestone; 9.5mm, 12.5mm and 19.0mm...

Local Worlds of Activation

DEFF Research Database (Denmark)

Jacobsson, Kerstin; Hollertz, Katarina; Garsten, Christina

2017-01-01

arrangements and the role of private services and actors in service delivery differed significantly too, ranging from strictly market-based forms of governance to classical public administration. The article moreover shows how the different activation approaches were reflected in the radically different usages...... from local politics, established local traditions, patterns of networking and modes of collaborating, as the notion of ‘local words of activation’ intends to capture....

Surfactant-enhanced aquifer remediation at the Portsmouth Gaseous Diffusion Plant

International Nuclear Information System (INIS)

Jackson, R.E.; Londergan, J.T.; Pickens, J.

1995-01-01

Many DOE facilities are situated in areas of sand and gravel which have become polluted with dense, non-aqueous phase liquids or DNAPLs, such as chlorinated solvents, from the various industrial operations at these facilities. The presence of such DNAPLs in sand and gravel aquifers is now recognized as the principal factor in the failure of standard ground-water remediation methods, i.e., open-quotes pump-and-treatclose quotes operations, to decontaminate such systems. The principal objective of this study is to demonstrate that multi-component DNAPLs can be readily solubilized in sand and gravel aquifers by dilute surfactant solutions

Geohydrology of the valley-fill aquifer in the Ramapo and Mahwah rivers area, Rockland County, New York

Science.gov (United States)

Moore, Richard Bridge; Cadwell, D.H.; Stelz, W.G.; Belli, J.L.

1982-01-01

This report is the eighth in a series of 11 map sets depicting geohydrologic conditions in selected aquifers in upstate New York. Geohydrologic data are compiled on six maps at 1:24,000 scale. Together, the maps provide a comprehensive overview of a major valley-fill aquifer in southeastern Rockland County. The maps include surficial geology, geologic sections, water-infiltration potential of soil zone, aquifer thickness, water-table elevations, well yields, and land use. The valley-fill deposits consists of alluvial silt and sand, glacial outwash (sand and gravel), ice-contact sand and gravel, till, and lacustrine silt and clay. The sand and gravel beds have relatively high permeabilities, whereas the till, silt, and clay deposits have relatively low permeabilities. Water-table conditions prevail in unconfined sand and gravel along the Ramapo River valley and much of the Mahwah River valley. Artesian conditions prevail in confined sand and gravel buried under silt and clay and till in parts of the Mahway valley. The aquifer is recharged throughout, where the land surface is most permeable and is greatest along the margin of the valley, where runoff from the hillsides is concentrated. The use of land overlying the aquifer is predominantly commercial, agricultural and residential, with lesser industrial uses. (USGS)

Local fields and their extensions

CERN Document Server

Fesenko, I B

2002-01-01

This book offers a modern presentation of local fields whose spectacular development was initiated almost one hundred years ago by K. Hensel. The volume consists of nine chapters divided into four parts: arithmetic properties of local fields, class field theory for various types of local fields and generalizations, explicit formulas for the Hilbert pairing, and Milnor K-groups of fields and of local fields. The first three parts essentially simplify, revise, and update the first edition. This second edition contains about sixty additional pages reflecting several aspects of the developments in local number theory in the last ten years. Exercises point to many other paths for exploration. The book is designed for graduate students and research mathematicians interested in local number theory and its applications in arithmetic algebraic geometry.

To renew local energy policies

International Nuclear Information System (INIS)

Bailleul, Esther; Alfano, Patrick; Ballan, Etienne; Bosboeuf, Pascale; Braun, Nicolas; Budin, Jacques-Olivier; Caron, Jean-Francois; Couturier, Christian; Dantec, Ronan; Ducolombier, Alexandre; Durand, Lucas; Haeringer, Nicolas; Izard, Charlotte; Jadot, Yannick; Joos, Marine; Landel, Pierre-Antoine; Le Du, Mathieu; Lucas, Guillaume; Maya, Michel; Moisan, Marie; Peullemeulle, Justine; Pin, Pascaline; Poize, Noemie; Regnier, Yannick; Rudinger, Andreas; Saultier, Patrick; Serne, Pierre; Zeroual, Bouchr; Arevalo, Henri; Bregeon, Anne; Vauquois, Victor; Aussavy, Gregoire

2016-08-01

Presented as a guide, this book proposes an operational and transverse approach to local action in the field of energy. It is illustrated by many field examples which show how actors have been able to (re)gain control of the energy issue. In the first part in which they present the main issues, the authors outline that local authorities are in front line for a European energy transition, recall the French legal framework for local energy transition, describe how to address local energy self-sufficiency, and comment stakes and levers for energy transition financing. The second part deals with action. The authors there describe how to manage a local energy transition, how to act transversally, how to get citizen involved, and how to relate energy transition and local development

Localized modes in optics of photonic liquid crystals with local anisotropy of absorption

Energy Technology Data Exchange (ETDEWEB)

Belyakov, V. A., E-mail: bel1937@mail.ru, E-mail: bel@landau.ac.ru [Russian Academy of Science, Landau Institute for Theoretical Physics (Russian Federation); Semenov, S. V. [National Research Center “Kurchatov Institute,” (Russian Federation)

2016-05-15

The localized optical modes in spiral photonic liquid crystals are theoretically studied for the certainty at the example of chiral liquid crystals (CLCs) for the case of CLC with an anisotropic local absorption. The model adopted here (absence of dielectric interfaces in the structures under investigation) makes it possible to get rid of mixing of polarizations on the surfaces of the CLC layer and of the defect structure and to reduce the corresponding equations to only the equations for light with polarization diffracting in the CLC. The dispersion equations determining connection of the edge mode (EM) and defect mode (DM) frequencies with the CLC layer parameters (anisotropy of local absorption, CLC order parameter) and other parameters of the DMS are obtained. Analytic expressions for the transmission and reflection coefficients of CLC layer and DMS for the case of CLC with an anisotropic local absorption are presented and analyzed. It is shown that the CLC layers with locally anisotropic absorption reduce the EM and DM lifetimes (and increase the lasing threshold) in the way different from the case of CLC with an isotropic local absorption. Due to the Borrmann effect revealing of which is different at the opposite stop-band edges in the case of CLC layers with an anisotropic local absorption the EM life-times for the EM frequencies at the opposite stop-bands edges may be significantly different. The options of experimental observations of the theoretically revealed phenomena are briefly discussed.

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. Phase 2: Solubilization test and partitioning interwell tracer tests. Final report

International Nuclear Information System (INIS)

1997-01-01

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. 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 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

Cost and Performance Report of Electrical Resistance Heating (ERH) for Source Treatment. Addendum

Science.gov (United States)

2008-09-29

remains and thin sandy layers. Patuxent Multiple-Layer Aquifer Sand, gray and yellow, with interbedded clay, kaolinized feldspar, pyrite and lignite...treatment. However, the post-treatment CVOC mass is likely to be even more sporadically dispersed than the pre-treatment CVOC mass, leading to similar (or

Manati: risks, uncertainties and technology in development of an offshore gas field in Brazil; Manati: riscos, incertezas e tecnologia no desenvolvimento de um campo de gas offshore no Brasil

Energy Technology Data Exchange (ETDEWEB)

Souza, Arlindo A.; Bernardi, Tiaraju P.; Salvador, Miriane C.; Assis, Carlos A. Silva; Assis, Pedro A.F.; Reis, Roberto C. [PETROBRAS, Rio de Janeiro, RJ (Brazil)

2008-07-01

The objective of this paper is to present a synthesis of Manati gas field development, discovered in 2000, in Bahia, detaching the main risks and uncertainties involved in the project. This project is quite challenge because of its great volume of gas and its localization, pertaining to an environment of sensible ecosystem. The presented study will discuss diverse economic solutions and innovative technologies that had been adopted. It will also aboard solutions as the method of gravel discarding, adaptation of the auto-elevator platforms involved in the development of the field and use of platform PMNT-1, totally automated and uninhabited. (author)

Isoperla vjosae sp. n., a new species of the Isoperla tripartita group from Albania (Plecoptera: Perlodidae).

Science.gov (United States)

Graf, Wolfram; Pauls, Steffen U; Vitecek, Simon

2018-01-09

In this contribution, we describe Isoperla vjosae sp. nov. from Albania. We characterize males, females, and larvae of the new species collected at the Vjosa River using morphological and molecular approaches. Isoperla vjosae sp.nov. is a member of the I. tripartita group, which is widely distributed in the Balkans. This new endemic species is being threatened by a proposed hydroelectric power dam on the Vjosa River impacting the type locality - a large, shifting gravel, low altitude River - an atypical habitat for larvae of the I. tripartita group. For the first time we use molecular tools to delineate Isoperla species from the Balkans.