Erosion-corrosion interactions and their affect on marine and offshore components

Energy Technology Data Exchange (ETDEWEB)

Wood, Robert JK [Surface Engineering and Tribology Group, School of Engineering Sciences, University of Southampton, SO17 1BJ (United Kingdom)

2004-07-01

The operation of modern fluid handling systems demands for low costs, reliability, longevity and no loss of fluid containment. All these can be achieved by minimising the material damage caused by the combined attack of solid particle or cavitation impingement and corrosion. This paper will cover the rationale behind the selection of erosion resistance surfaces for fluid handling equipment and highlight the complexities encountered when these surfaces are exposed to environments which contain sand particles or cavitation in a corrosive medium. The erosion and erosion-corrosion performance of a variety of coatings and bulk surfaces will be discussed using volume loss rate versus sand impact energy maps. Recent research into the erosion-corrosion of polymer coatings, PEO and HVOF aluminium and nickel aluminium bronze coatings will be reviewed. Electrochemical techniques designed to monitor the erosion-corrosion mechanisms and coating integrity will be presented and used to quantify the synergistic terms present when both erosion and corrosion act concurrently. (author)

Wind erosion research at an uranium mill tailings site

International Nuclear Information System (INIS)

Sehmel, G.A.

1977-07-01

A uranium mill tailings pile at Grants, New Mexico, was selected for wind erosion research since the configuration provides flat area containing fine sand and made up of larger particles. The wind erosion experiment is discussed. Experimental equipment consists of meteorological instrumentation to automatically activate air samplers as a function of wind speed increments and direction, particle cascade impactors to measure airborne respirable concentrations as a function of particle size, inertial impaction devices to measure nonrespirable fluxes of airborne particles, a virtual particle cascade impactor to measure airborne concentrations of toxic trace elements, and soil depth gauges to measure changes in surface soil elevations as a function of time. Both radioactive particles as well as toxic trace element concentrations are measured. Radioactive particles are measured with both particle cascade impactors as well as high-volume air samplers. In contrast, toxic trace element airborne concentrations are measured only with a two-stage virtual particle cascade impactor. Fluxes of nonrespirable airborne particles are measured with inertial impaction devices. At particle cascade impactor sites, a rotating cyclone preseparator collects nonrespirable particles. In addition at all sites, fluxes of nonrespirable particles are measured using an open cavity inertial impaction device

Hydro-abrasive erosion of hydraulic turbines caused by sediment - a century of research and development

Science.gov (United States)

Felix, D.; Albayrak, I.; Abgottspon, A.; Boes, R. M.

2016-11-01

Hydro-abrasive erosion of hydraulic turbines is an economically important issue due to maintenance costs and production losses, in particular at high- and medium-head run-of- river hydropower plants (HPPs) on sediment laden rivers. In this paper, research and development in this field over the last century are reviewed. Facilities for sediment exclusion, typically sand traps, as well as turbine design and materials have been improved considerably. Since the 1980s, hard-coatings have been applied on Francis and Pelton turbine parts of erosion-prone HPPs and became state-of-the-art. These measures have led to increased times between overhauls and smaller efficiency reductions. Analytical, laboratory and field investigations have contributed to a better processes understanding and quantification of sediment-related effects on turbines. More recently, progress has been made in numerical modelling of turbine erosion. To calibrate, validate and further develop prediction models, more measurements from both physical model tests in laboratories and real-scale data from HPPs are required. Significant improvements to mitigate hydro-abrasive erosion have been achieved so far and development is ongoing. A good collaboration between turbine manufacturers, HPP operators, measuring equipment suppliers, engineering consultants, and research institutes is required. This contributes to the energy- and cost-efficient use of the worldwide hydropower potential.

Revegetation and management of tailings sand slopes from tar sand extraction: 1978 results

Energy Technology Data Exchange (ETDEWEB)

Rowell, M J

1979-01-01

The results are reported of research into the revegetation of two areas on a steeply sloping dike composed of tailings sand from tar sand extraction at the Great Canadian Oil Sand Limited plant at Fort McMurray, Alberta. One area was seeded with three pasture grasses and two legumes in 1971 after the slope surface had been mixed with peat to a depth of 15 cm. A second area had been amended with peat or peat and overburden and differing rates of fertilizer added. A mix containing nine grasses, four legumes, and oats, as a companion crop, was seeded in July 1976. The objectives of the research were to study methods for the establishment of a stable vegetative cover that would prevent erosion of the slope and, in time, might become a self maintaining unit. Tillage of soil amendments to a depth of 15 cm and 30 cm were compared in promoting deeper rooting and stabilizing of the slope.

An Outflow Event on the Left Side of Harvey: Erosion of Barrier Sand and Seaward Transport Through Aransas Pass

Science.gov (United States)

Goff, J.; Swartz, J. M.; Gulick, S. P. S.

2017-12-01

Barrier islands provide critical support and protection for coastal communities and ecosystems, but are potentially vulnerable to net losses of sand during major storms. Evidence from satellite imagery, ground observations and tide stations indicates that Hurricane Harvey in 2017 caused a large outflow event of waters moving from the bays out towards the sea in the Port Aransas, Texas region. Rather than just an ebb of a storm surge, this event may have been driven by seaward-directed winds on the left side of storm. Less than a month after landfall, we conducted a swath mapping and sampling survey in Lydia Ann Channel and Aransas Pass, where we had earlier mapped in 2009 and 2012 as part of the UT marine geology and geophysical field course. These waterways are important conduits linking Corpus Christi and Aransas bays to the Gulf of Mexico. This multi-year record allows us to gauge the impact of the outflow event on these waterways in the context of "normal" coastal processes. Both satellite imagery and sonar mapping reveal that the outflow event caused significant erosion, both on land and beneath the water, along the edges of Lydia Ann Channel and Corpus Christi ship channel. It also caused seaward-directed flow and erosion through breaches in the foredunes along southern San Jose Island, from waters that overtopped Lydia Ann Channel. Much of the sand that was transported seaward settled in Lydia Ann Channel and Aransas Pass (up to 6.5 m accumulation), possibly during the waning stages of the event. However, a likely large (but unknown) quantity of barrier and estuarine sand could have been transported well out to sea, beyond the jetties, at the peak of the event. If so, it would have resulted in a net loss of sand from the barrier island system.

Erosion Testing of Coatings for V-22 Aircraft Applications

Directory of Open Access Journals (Sweden)

G. Y. Richardson

2003-01-01

Full Text Available High-velocity (183 m/sec sand erosion tests in a wind tunnel were conducted to evaluate developmental coatings from three separate companies under funding by the Navy's phase I small business innovative research program. The purpose of the coatings was to address a particular problem the V-22 tilt-rotor aircraft (Osprey was having with regard to ingestion of sand particles by a titanium impeller that was associated with the aircraft's environmental control system. The three coatings that were deposited on titanium substrates and erosion-tested included (1 SixCy/DLC multilayers deposited by chemical vapor deposition (CVD; (2 WC/TaC/TiC processed by electrospark deposition; and (3 polymer ceramic mixtures applied by means of an aqueous synthesis. The erosion test results are presented; they provided the basis for assessing the suitability of some of these coatings for the intended application.

Testing and prediction of erosion-corrosion for corrosion resistant alloys used in the oil and gas production industry

Science.gov (United States)

Rincon, Hernan E.

The corrosion behavior of CRAs has been thoroughly investigated and documented in the public literature by many researchers; however, little work has been done to investigate erosion-corrosion of such alloys. When sand particles are entrained in the flow, the degradation mechanism is different from that observed for sand-free corrosive environment. There is a need in the oil and gas industry to define safe service limits for utilization of such materials. The effects of flow conditions, sand rate, pH and temperature on the erosion-corrosion of CRAs were widely studied. An extensive experimental work was conducted using scratch tests and flow loop tests using several experimental techniques. At high erosivity conditions, a synergistic effect between erosion and corrosion was observed. Under the high sand rate conditions tested, erosivity is severe enough to damage the passive layer protecting the CRA thereby enhancing the corrosion rate. In most cases there is likely a competition between the rates of protective film removal due to mechanical erosion and protective film healing. Synergism occurs for each of the three alloys examined (13Cr and Super13Cr and 22Cr); however, the degree of synergism is quite different for the three alloys and may not be significant for 22Cr for field conditions where erosivities are typically much lower that those occurring in the small bore loop used in this research. Predictions of the corrosion component of erosion-corrosion based on scratch test data compared reasonably well to test results from flow loops for the three CRAs at high erosivity conditions. Second order behavior appears to be an appropriate and useful model for representing the repassivation process of CRAs. A framework for a procedure to predict penetration rates for erosion-corrosion conditions was developed based on the second order model behavior observed for the re-healing process of the passive film of CRAs and on computational fluid dynamics (CFD) simulations

Advancing internal erosion monitoring using seismic methods in field and laboratory studies

Science.gov (United States)

Parekh, Minal L.

This dissertation presents research involving laboratory and field investigation of passive and active methods for monitoring and assessing earthen embankment infrastructure such as dams and levees. Internal erosion occurs as soil particles in an earthen structure migrate to an exit point under seepage forces. This process is a primary failure mode for dams and levees. Current dam and levee monitoring practices are not able to identify early stages of internal erosion, and often the result is loss of structure utility and costly repairs. This research contributes to innovations for detection and monitoring by studying internal erosion and monitoring through field experiments, laboratory experiments, and social and political framing. The field research in this dissertation included two studies (2009 and 2012) of a full-scale earthen embankment at the IJkdijk in the Netherlands. In both of these tests, internal erosion occurred as evidenced by seepage followed by sand traces and boils, and in 2009, eventual failure. With the benefit of arrays of closely spaced piezometers, pore pressure trends indicated internal erosion near the initiation time. Temporally and spatially dense pore water pressure measurements detected two pore water pressure transitions characteristic to the development of internal erosion, even in piezometers located away from the backward erosion activity. At the first transition, the backward erosion caused anomalous pressure decrease in piezometers, even under constant or increasing upstream water level. At the second transition, measurements stabilized as backward erosion extended further upstream of the piezometers, as shown in the 2009 test. The transitions provide an indication of the temporal development and the spatial extent of backward erosion. The 2012 IJkdijk test also included passive acoustic emissions (AE) monitoring. This study analyzed AE activity over the course of the 7-day test using a grid of geophones installed on the

The Geodiversity in Drift Sand Landscapes of The Netherlands

Science.gov (United States)

van den Ancker, Hanneke; Jungerius, Pieter Dirk; Riksen, Michel

2015-04-01

metres high. They are common near villages. They originated through sand blown from fallow agricultural fields and local overgrazing. They vary in age from prehistoric to modern time and are now mostly planted with forests. Third are the linear drift sand areas with one to three metre high ridges that align old roads and originated through dust whirled up by horses and carriages over many centuries. They also occurs within drift sands of the first system. In the re-stabilization of reactivated drift sands, differences in geodiversity on a still more detailed scale are important (Ancker, Jungerius et al. 2013). Even a small change in slope can cause primary dunes to develop and stop wind erosion. Gradually the geodiversity aspects are recognized as relevant for the management of active and fossil drift sands, and also is becoming a management issue in itself. An important future research issue is the completion of the Drift Sand Atlas, a project that describes the geodiversity aspects of all drift sand areas of The Netherlands. This project has been retarded by lack of means. Knowledge of the geodiversity also is important for correct sampling of C14 and luminescence data. Other future research includes the processes that caused the formation of 'randwallen' (rim walls), rates of water and wind erosion and soil formation and links between flora, fauna and Natura 2000 species. References

Erosion in the Beaches of Crete

Science.gov (United States)

Synolakis, C. E.; Foteinis, S.; Voukouvalas, V.; Kalligeris, N.

2009-04-01

In the past decade, erosion rates for the coastlines of Greece are rapidly increasing. Many beaches on the northern coast of the island have substantially retreated, while others have disappeared or will disappear within the present or the following decade if no action is taken. For the better understanding and visualization of the current situation, specific examples of rapid erosion are described and afterwards we speculate as to the causes. We infer that, as in other parts of the Mediterranean, the causes are anthropogenic and include removal of sand dunes to build roads, sand mining from beaches and rivers, permanent building construction within the active coastal zone, on or too close to shoreline, and poor design of coastal structures. The reason behind the rapid erosion of Greece coastlines is the complete lack of any semblance of coastal zone management and antiquated legislation. We conclude that unless urgent measures for the protection and even salvation of the beaches are taken and if the sand mining and dune removal does not stop, then several beaches will disappear within the present and the following decade.

Coastal Erosion Control Methods

Science.gov (United States)

Greene, V.

2016-12-01

Coastal erosion is bad because the ecosystem there will be washed away and the animals could drown or be displaced and have to adapt to a new ecosystem that they are not prepared for. I'm interested in this problem because if there aren't beaches when I grow up I won't be able to do the things I would really like to do. I would like to be a marine biologist. Secondly, I don't want to see beach houses washed away. I would like to see people live in harmony with their environment. So, to study ways in which to preserve beaches I will make and use models that test different erosion controls. Two different ideas for erosion control I tested are using seaweed or a rock berm. I think the rock berm will work better than the model of seaweed because the seaweed is under water and the waves can carry the sand over the seaweed, and the rock berm will work better because the rocks will help break the waves up before they reach the shore and the waves can not carry the sand over the rocks that are above the water. To investigate this I got a container to use to model the Gulf of Mexico coastline. I performed several test runs using sand and water in the container to mimic the beach and waves from the Gulf of Mexico hitting the shoreline. I did three trials for the control (no erosion control), seaweed and a rock berm. Rock berms are a border of a raised area of rock. The model for seaweed that I used was plastic shopping bags cut into strips and glued to the bottom of my container to mimic seaweed. My results were that the control had the most erosion which ranged from 2.75 - 3 inches over 3 trials. The seaweed was a little better than the control but was very variable and ranged from 1.5 - 3 inches over 3 trials. The rock berm worked the best out of all at controlling erosion with erosion ranging from 1.5 - 2 inches. My hypothesis was correct because the rock berm did best to control erosion compared to the control which had no erosion control and the model with seaweed.

The Mechanism behind Erosive Bursts in Porous Media

Science.gov (United States)

Jaeger, Robin; Mendoza, Miller; Herrmann, Hans

2017-11-01

We implemented a new model based on the Lattice Boltzmann method to simulate erosion and deposition in suspension flows through porous media. Using this model we show that the cause of erosive bursts in filtration experiments is the re-opening of clogged pores when the pressure difference between two opposite sites of the pore surpasses a certain threshold. We perform numerical simulations and find excellent agreement to experimental results when comparing shape and size distribution of pressure loss jumps, which are the direct result of erosive bursts. Furthermore, we find that erosive bursts only occur for pressure gradient thresholds within the range of two critical values, independent on how the flow is driven. We believe that our findings provide a better understanding of sudden sand production in oil wells and breakthrough in filtration. European Research Council (ERC) Advanced Grant 319968-FlowCCS.

MouldingSandDB – a modern database storing moulding sands properties research results

Directory of Open Access Journals (Sweden)

J. Jakubski

2011-01-01

Full Text Available The complexity of foundry processes requires the use of modern, advanced IT tools for optimization, storage and analysis of t echnicaldata. Properties of moulding and core sands that are collected in research laboratories, manufacturers, and finally in the foundries, are not in use later on. It seems important to create a database that will allow to use the results stored, along with the possibility of searching according to set criteria, adjusted to casting practice. This paper presents part of the database named „MouldingSandDB”, which allows to collect and search data for synthetic moulding sands.

Predicting wear of hydrotransport pipelines in oil sand slurries

Energy Technology Data Exchange (ETDEWEB)

Been, J.; Lu, B.; Wolodko, J. [Alberta Research Council, Edmonton, AB (Canada); Kiel, D. [Coanda Research and Development Corp., Burnaby, BC (Canada)

2008-07-01

An overview of erosion and corrosion methods and techniques was presented. Wear to pipelines is influenced by slurry flow and chemistry; solids loading; and electrochemical interactions. While several experimental techniques have been developed to rank the performance of different pipeline materials, experiments do not currently provide accurate quantitative prediction of pipeline wear in the field. Rotating cylinder electrodes (RCE) and jet impingement methods are used to study the effect of flow velocity on corrosion rate. Slurry pot erosion-corrosion testers are used to rank materials for use in more dilute, less turbulent slurries. Coriolois slurry erosion testers are used to rank the erosion resistance of different pipeline materials. A pilot-scale flow loop is now being constructed by the Alberta Research Council (ARC) in order to replicate wet erosion phenomena in oil sands applications. The flow loop will be used to simulate the field conditions of oil sands pipelines and develop predictive wear data and models. Coulombic shear stress and characteristic wall velocities have been determined using a 2-layer model designed to represent flow as 2 distinct layers. To date, the flow loop pilot study has demonstrated that wear rates in smaller diameter flow loops are not significantly different than larger diameter field installations. Preliminary calculations have demonstrated that the flow loop can be used to accurately simulate the hydrodynamics and wear typically experienced in field slurry flows. 67 refs., 2 tabs., 7 figs.

Sediment Source Fingerprinting of the Lake Urmia Sand Dunes.

Science.gov (United States)

Ahmady-Birgani, Hesam; Agahi, Edris; Ahmadi, Seyed Javad; Erfanian, Mahdi

2018-01-09

Aeolian sand dunes are continuously being discovered in inner dry lands and coastal areas, most of which have been formed over the Last Glacial Maximum. Presently, due to some natural and anthropogenic implications on earth, newly-born sand dunes are quickly emerging. Lake Urmia, the world's second largest permanent hypersaline lake, has started shrinking, vast lands comprising sand dunes over the western shore of the lake have appeared and one question has been playing on the minds of nearby dwellers: where are these sand dunes coming from, What there was not 15 years ago!! In the present study, the determination of the source of the Lake Urmia sand dunes in terms of the quantifying relative contribution of each upstream geomorphological/lithological unit has been performed using geochemical fingerprinting techniques. The findings demonstrate that the alluvial and the fluvial sediments of the western upstream catchment have been transported by water erosion and they accumulated in the lower reaches of the Kahriz River. Wind erosion, as a secondary agent, have carried the aeolian sand-sized sediments to the sand dune area. Hence, the Lake Urmia sand dunes have been originating from simultaneous and joint actions of alluvial, fluvial and aeolian processes.

Extensive formation of sinkholes in unconsolidated rock due to underground erosive removal of sand at a marginal batter of an opencast mine - causes, process and geotechnical safety measures. Grossflaechige Erdfallbildungen im Lockergestein durch unterirdische erosive Ausraeumung von Sand and einer Tagebauendboeschung - Ursachen, Verlauf und geotechnische Sicherung

Energy Technology Data Exchange (ETDEWEB)

Pfeiffer, H

1991-08-01

When the ground water rose in the marginal batter of an opencast mine damage occurred. This was caused by the processes of internal erosion and suffusion in fine sand layers of slight thickness and by the disintegration of the overlying strata due to the formation of sinkholes. Effective safety measures involved lowering the ground-water level in the zone immediately in front of the area in question and installing an auxiliary filter unit at the marginal batter. (orig.).

Sands at Gusev Crater, Mars

Science.gov (United States)

Cabrol, Nathalie A.; Herkenhoff, Kenneth E.; Knoll, Andrew H.; Farmer, Jack D.; Arvidson, Raymond E.; Grin, E.A.; Li, Ron; Fenton, Lori; Cohen, B.; Bell, J.F.; Yingst, R. Aileen

2014-01-01

Processes, environments, and the energy associated with the transport and deposition of sand at Gusev Crater are characterized at the microscopic scale through the comparison of statistical moments for particle size and shape distributions. Bivariate and factor analyses define distinct textural groups at 51 sites along the traverse completed by the Spirit rover as it crossed the plains and went into the Columbia Hills. Fine-to-medium sand is ubiquitous in ripples and wind drifts. Most distributions show excess fine material, consistent with a predominance of wind erosion over the last 3.8 billion years. Negative skewness at West Valley is explained by the removal of fine sand during active erosion, or alternatively, by excess accumulation of coarse sand from a local source. The coarse to very coarse sand particles of ripple armors in the basaltic plains have a unique combination of size and shape. Their distribution display significant changes in their statistical moments within the ~400 m that separate the Columbia Memorial Station from Bonneville Crater. Results are consistent with aeolian and/or impact deposition, while the elongated and rounded shape of the grains forming the ripples, as well as their direction of origin, could point to Ma'adim Vallis as a possible source. For smaller particles on the traverse, our findings confirm that aeolian processes have dominated over impact and other processes to produce sands with the observed size and shape patterns across a spectrum of geologic (e.g., ripples and plains soils) and aerographic settings (e.g., wind shadows).

The water erosion processes in the retreat erosive of cliff on soft rocks in the province of Cadiz (Spain)

International Nuclear Information System (INIS)

Rendon Aragon, J. J.; Gracia Prieto, F. J.; Rio Rodriguez, L. del

2009-01-01

The littoral cliffs on soft materials of the Atlantic Cadiz coast show an important activity of the fresh water erosion processes, sometimes even more significant than the marine erosion processes. The connection of the lower cliffs with sandy beaches favours aeolian sand invasion, which fills previous rills and reduces the water erosion intensity by increasing infiltration. Cliff retreat and rill erosion measurement by using erosion sticks has shown very variables values, most of them higher than the estimated error of the employed methods. This indicates the existence of other factors influencing the distribution of water erosion processes along these cliffs, which have to be studied through different techniques. (Author) 5 refs.

Computational analysis of Pelton bucket tip erosion using digital image processing

Science.gov (United States)

Shrestha, Bim Prasad; Gautam, Bijaya; Bajracharya, Tri Ratna

2008-03-01

Erosion of hydro turbine components through sand laden river is one of the biggest problems in Himalayas. Even with sediment trapping systems, complete removal of fine sediment from water is impossible and uneconomical; hence most of the turbine components in Himalayan Rivers are exposed to sand laden water and subject to erode. Pelton bucket which are being wildly used in different hydropower generation plant undergoes erosion on the continuous presence of sand particles in water. The subsequent erosion causes increase in splitter thickness, which is supposed to be theoretically zero. This increase in splitter thickness gives rise to back hitting of water followed by decrease in turbine efficiency. This paper describes the process of measurement of sharp edges like bucket tip using digital image processing. Image of each bucket is captured and allowed to run for 72 hours; sand concentration in water hitting the bucket is closely controlled and monitored. Later, the image of the test bucket is taken in the same condition. The process is repeated for 10 times. In this paper digital image processing which encompasses processes that performs image enhancement in both spatial and frequency domain. In addition, the processes that extract attributes from images, up to and including the measurement of splitter's tip. Processing of image has been done in MATLAB 6.5 platform. The result shows that quantitative measurement of edge erosion of sharp edges could accurately be detected and the erosion profile could be generated using image processing technique.

Continued studies of soil improvement and revegetation of tailings sand slopes. Environmental Research Monograph 1977-4

Energy Technology Data Exchange (ETDEWEB)

Rowell, M J

1977-01-01

Fertilizer studies continued on a 5-year old revegetated area on a tailings sand dike in the Athabasca Tar Sands area. In June 1976 levels of available N, P, K, and S were adequate for plant growth. However, even where fertilizers were added levels of mineral N had dropped to low levels by September. Plant top production early in the 1976 season was increased by application of nitrogen fertilizer during the previous August. Erosion of the area was negligible in 1976. In the new revegetation experiments on steep tailings and slopes, erosion could be minimized by the rapid establishment of a plant cover. Nutrient losses in surface water runoff amounted to a maximum of only 2.6 kg N, 0.4 kg P, 4.1 kg K and 3.4 kg S/ha in the treatments studied. Water infiltration into the dike was rapid and varied between 24.0 and 30.5 cm/h. Estimates suggested that between 13 and 34% of the intercepted rainfall leached below the 30 cm depth while plants were being established during the first year of growth. Estimates of nutrient losses below the root zone (30 cm) ranged between 1.3 and 31.2 kg N/ha; <0.1 kg P/ha; 1.1 and 10.1 kg K/ha and 4.8 to 38.1 kg S/ha in the different treatments studied. The seed mix used contained oats as a nurse crop and 9 grass and 4 legume species. Plant growth was adequate to protect the soil surface from serious erosion. The dry weight production by the oats was considerably greater than for either the grasses or legumes. The cover produced by grasses and legumes alone would have been adequate in terms of erosion control except in those treatments involving heavy applications of mine overburdens. The dry weight production of root and shoot tissues was about the same. Root growth was largely restricted to the surface 15 cm. Total numbers of bacteria, fungi and actinomycetes as well as total soil respiration was considerably greater in soils from the revegetation experiments in comparison to samples of fresh or weathered tailings sand.

Evaluation of the Synergistic Effect of Erosion-Corrosion on AISI 4330 Steel in Saline-Sand Multiphase Flow by Electrochemical and Gravimetric Techniques

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Dario Yesid Peña Ballesteros

2016-01-01

Full Text Available The synergistic effects of fluid flow, sand particles, and solution pH on erosion-corrosion of AISI 4330 steel alloy in saline-sand medium were studied through a rotating cylinder electrode (RCE system by weight-loss and electrochemical measurements. The worn surface was analyzed by X-ray diffraction (XRD and scanning electron microscopy (SEM. Results show that, under all the test conditions assessed, the passivity of the steel alloy could not be maintained; as a result, an activation mechanism dominates the corrosion process of steel alloy. Furthermore, the potentiodynamic curves show that, with the increasing of the electrode flow rate and particle size, the anodic current density increased, which is due to deterioration of the electrode by the impacting slurry. Although the increase of particle size affects the anodic current density, the effect of particle size does not cause a significant change in the polarization behavior of the steel electrode. The electrochemical impedance and potentiodynamic curves suggest that erosion-corrosion phenomenon of the ASISI 4330 steel is under mixed control of mass transport and charge transfer. The inductive loops formed in the impedance plots are representative of an increase in roughness of the electrode caused by the particles impacting at the surface. The change in the passivity of the steel alloy as the pH is altered plays an important role in the corrosion rate.

Tillage techniques to reactivate aeolian erosion on inland drift-sand

NARCIS (Netherlands)

Riksen, M.J.P.M.; Goossens, D.

2005-01-01

The inland drift-sand areas in northern Europe are characterised by a rapid decline in both aeolian activity and areal size. Many former drift-sand surfaces have become immobilised by natural or man-induced processes, such as conversion into forest or other terrain for agricultural, economic or

Wind erosion control of soils using polymeric materials

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Mohammad Movahedan

2012-07-01

Full Text Available Wind erosion of soils is one of the most important problems in environment and agriculture which could affects several fields. Agricultural lands, water reservoires, irrigation canals, drains and etc. may be affected by wind erosion and suspended particles. As a result wind erosion control needs attention in arid and semi-arid regions. In recent years, some polymeric materials have been used for improvement of structural stability, increasing aggregate stability and soil stabilization, though kind of polymer, quantity of polymer, field efficiency and durability and environmental impacts are some important parameters which should be taken into consideration. In this study, a Polyvinil Acetate-based polymer was used to treat different soils. Then polymer-added soil samples were investigated experimentally in a wind tunnel to verify the effecte of polymer on wind erosion control of the soils and the results were compared with water treated soil samples. The results of wind tunnel experiments with a maximum 26 m/s wind velocity showed that there was a significat difference between the erosion of polymer treated and water treated soil samples. Application of 25g/m2 polymer to Aeolian sands reduced the erosion of Aeolian sands samples to zero related to water treated samples. For silty and calyey soils treated by polymer, the wind erosion reduced minimum 90% in relation to water treated samples.

Institutional landmarks in Brazilian research on soil erosion: a historical overview

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Tiago Santos Telles

2013-12-01

Full Text Available The problem of soil erosion in Brazil has been a focus of agricultural scientific research since the 19th century. The aim of this study was to provide a historical overview of the institutional landmarks which gave rise to the first studies in soil erosion and established the foundations of agricultural research in Brazil. The 19th century and beginning of the 20th century saw the founding of a series of institutions in Brazil, such as Botanical Gardens, executive institutions, research institutes, experimental stations, educational institutions of agricultural sciences, as well as the creation and diversification of scientific journals. These entities, each in its own way, served to foster soil erosion research in Brazil. During the Imperial period (1808-1889, discussions focused on soil degradation and conserving the fertility of agricultural land. During the First Republic (1889-1930, with the founding of various educational institutions and consolidation of research on soil degradation conducted by the Agronomic Institute of Campinas in the State of São Paulo, studies focused on soil depletion, identification of the major factors causing soil erosion and the measures necessary to control it. During the New State period (1930-1945, many soil conservation practices were developed and disseminated to combat erosion and field trials were set up, mainly to measure soil and water losses induced by hydric erosion. During the Brazilian New Republic (1945-1964, experiments were conducted throughout Brazil, consolidating soil and water conservation as one of the main areas of Soil Science in Brazil. This was followed by scientific conferences on erosion and the institutionalization of post-graduate studies. During the Military Regime (1964-1985, many research and educational institutions were founded, experimental studies intensified, and coincidently, soil erosion reached alarming levels which led to the development of the no-tillage system.

Field testing, comparison, and discussion of five aeolian sand transport measuring devices operating on different measuring principles

NARCIS (Netherlands)

Goossens, Dirk; Nolet, Corjan; Etyemezian, Vicken; Duarte-campos, Leonardo; Bakker, Gerben; Riksen, Michel

2018-01-01

Five types of sediment samplers designed to measure aeolian sand transport were tested during a wind erosion event on the Sand Motor, an area on the west coast of the Netherlands prone to severe wind erosion. Each of the samplers operates on a different principle. The MWAC (Modified Wilson And

Field testing, comparison, and discussion of five aeolian sand transport measuring devices operation on different measuring priciples

NARCIS (Netherlands)

Goossens, Dirk; Nolet, C.; Etyemezian, Vicken; Duarte-Campos, Leonardo; Bakker, G.; Riksen, M.J.P.M.

2018-01-01

Five types of sediment samplers designed to measure aeolian sand transport were tested during a wind erosion event on the Sand Motor, an area on the west coast of the Netherlands prone to severe wind erosion. Each of the samplers operates on a different principle. The MWAC (Modified Wilson And

Impacts of sand and dust storms on agriculture and potential agricultural applications of a SDSWS

International Nuclear Information System (INIS)

Stefanski, R; Sivakumar, M V K

2009-01-01

This paper will give an overview of the various impacts of sand and dust storms on agriculture and then address the potential applications of a Sand and Dust Storm Warning System (SDSWS) for agricultural users. Sand and dust storms have many negative impacts on the agricultural sector including: reducing crop yields by burial of seedlings under sand deposits, the loss of plant tissue and reduced photosynthetic activity as a result of sandblasting, delaying plant development, increasing end-of-season drought risk, causing injury and reduced productivity of livestock, increasing soil erosion and accelerating the process of land degradation and desertification, filling up irrigation canals with sediments, covering transportation routes, affecting water quality of rivers and streams, and affecting air quality. One positive impact is the fertilization of soil minerals to terrestrial ecosystems. There are several potential agricultural applications of a SDSWS. The first is to alert agricultural communities farmers to take preventive action in the near-term such as harvesting maturing crops (vegetables, grain), sheltering livestock, and strengthening infrastructure (houses, roads, grain storage) for the storm. Also, the products of a SDSWS could be used in for monitoring potential locust movement and post-storm crop damage assessments. An archive of SDSWS products (movement, amount of sand and dust) could be used in researching plant and animal pathogen movement and the relationship of sand and dust storms to disease outbreaks and in developing improved soil erosion and land degradation models.

Effect of compost on erodibility of loamy sand under simulated rainfall

DEFF Research Database (Denmark)

Arthur, Emmanuel; Cornelis, W.M.; Vermang, J.

2011-01-01

Three types of composts [vegetable, fruit and yard waste compost (VFYW), garden waste compost (GW), and spent mushroom compost (SM)] were applied at a rate of 30 m3 ha−1 for 10 years to loamy sand, to determine its effect on the aggregate stability and susceptibility to water erosion. Aggregate...... significant improvement for any of the compost types. SM application resulted in a significant increase (51%) in the shear strength of the soil after rainfall. Long term compost application does not appreciably improve the resistance of loamy sand to water erosion....

Erosion resistance of pipe bends with bio-inspired internal surfaces

Science.gov (United States)

Zhang, Chengchun; Matar, Omar

2013-11-01

Guided by the structure of a shell surface, a bio-inspired surface is proposed to enhance the erosion resistance of pipe bends carrying crude-oil and sand in the turbulent flow regime. A comparison of the erosion rate between a smooth bend and the bio-inspired one is carried out using numerical simulations: large eddy simulations are used to simulate turbulence, and these are coupled to a discrete element method for the solid particles. The results indicate that the bio-inspired surface can control effectively the liquid-solid flow near the wall, and decrease the particle-wall force. This, then, leads to a reduction in the erosion rate brought about by the sand transported by the crude-oil in the pipe bend. The China Scholarship Council is gratefully acknowledged.

The water erosion processes in the retreat erosive of cliff on soft rocks in the province of Cadiz (Spain); Los procesos de erosion hidrica en el retroceso erosivo de acantilados sobre rocas blandas en la provincia de Cadiz

Energy Technology Data Exchange (ETDEWEB)

Rendon Aragon, J. J.; Gracia Prieto, F. J.; Rio Rodriguez, L. del

2009-07-01

The littoral cliffs on soft materials of the Atlantic Cadiz coast show an important activity of the fresh water erosion processes, sometimes even more significant than the marine erosion processes. The connection of the lower cliffs with sandy beaches favours aeolian sand invasion, which fills previous rills and reduces the water erosion intensity by increasing infiltration. Cliff retreat and rill erosion measurement by using erosion sticks has shown very variables values, most of them higher than the estimated error of the employed methods. This indicates the existence of other factors influencing the distribution of water erosion processes along these cliffs, which have to be studied through different techniques. (Author) 5 refs.

experimental studies of sand production from unconsolidated

African Journals Online (AJOL)

ES Obe

aDepartment of Chemical Engineering, University of Lagos, Lagos, Nigeria. bDepartment of Petroleum ... as risk of well failure, erosion of pipelines and surface facilities, sand separa- ... ment, theoretical and numerical analysis have lead to the ...

Is splash erosion potential species specific? Measuring of splash erosion potential under forest in different succession stages along a biodiversity gradient in the humid subtropics

Science.gov (United States)

Geißler, C.; Kühn, P.; Scholten, T.

2009-04-01

It is widely accepted that (forest) vegetation is a key control for the type and intensity of soil erosion. The current paradigm is that natural or quasi-natural vegetation protects the soil from erosion and that agricultural vegetation or land use generally enhances erosion. The latter was in focus of most research during the last decades and less interest was paid on natural systems, which are more difficult to study. Nevertheless, afforestation is widely used as a measure of soil protection against soil erosion. Rainfall can be highly erosive particularly in the humid subtropics. Regarding climate change, also precipitation regime may change in direction to even more severe storms and higher rainfall intensities; it is a research field of growing importance. Key mechanisms of a vegetation cover in reducing or enhancing erosion are modifications of drop-size distribution, retention of raindrop impact on the soil and changes in amount and spatial distribution of rainfall at the ground surface. Controlling determinants are rainfall intensity, drop size distribution, drop fall velocity, height of the canopy as well as density of the canopy, crown and leaf traits, LAI and coverage by a litter layer. Large drops are supposed to be significant sources of splash detachment in forests (Brandt 1989; Vis 1986). However, the mechanisms of reducing (or enhancing?) splash detachment under forest in relation to species richness and species composition are not well understood. Some studies indicate that raindrop impact is species specific (Calder 2001; Nanko et al. 2006) and some neglect the effects of species specific impacts (Foot & Morgan 2005). Our research uses different methods of rainfall characterization (splash cups, tipping-bucket rain gauge, laser distrometer) to reveal the described mechanisms from the canopy through different vegetation layers to the ground. First results of splash cup measurements (revised after Ellison 1947) show that sand loss under vegetation

Monitoring geo-biodiversity interactions of a restored inland drift-sand cell in Nieuw Bergen (Li)

Science.gov (United States)

Jungerius, Pieter Dirk; van den Ancker, Hanneke; Arts, Andries; Borkent, Ido; Ketner-Oostra, Rita; Ketner, Pieter

2013-04-01

In 2002, a research was carried out by Jungerius, van den Ancker, Ketner-Oostra and Evers to see if it was possible to restore active inland drift-sand areas in National Park De Maasduinen in Nieuw Bergen, Limburg. The active drift-sand had completely disappeared from the area by nitrogen-rich precipitation. It was decided to try and restore the activity depicted on the first aerial photographs in 1933, if soil profile development and Natura 2000 species allowed this. The areas stabilized since then were overgrown, dominantly by the invasive moss Campylopus introflexus, a species introduced to the Netherlands by tanks during World War II. Areas colonized by Natura 2000 lichens were spared as centres for re-colonization. The research gave insight in the elongated geomorphological cell-structure of the original drift-sands and the rate of soil development after stabilisation. In 2005, the first active drift-sand cell was restored by increasing the erodibility of the terrain, by mechanically removing the sod and up to 5 cm thick soil formed since 1933, and increasing the erosivity of the wind by removing trees, mainly in the upwind direction. In 2008 a second cell was restored, and a third one in 2011. A monitoring programme was set up for the first cell to improve our understanding of stabilization and geodiversity-biodiversity interactions in drift-sand areas. Lines of erosion pins were monitored at regular intervals for a five year period. Aerial photographs made in 2005 and 2008 showed the pattern of stabilization of the moving sand. The poster will present the results of these experiments. In 2012, five years after the restoration, the active drift-sand cell was stable again and had turned into an open dry grassland, almost completely dominated by the Natura 2000 species Corynephorus canescens. Unfortunately several of the areas that were spared as centres for re-colonization of Natura 2000 lichens lay in the sand transport zone and had acted as sandtraps, and

Production and global transport of Titan's sand particles

Science.gov (United States)

Barnes, Jason W.; Lorenz, Ralph D.; Radebaugh, Jani; Hayes, Alexander G.; Arnold, Karl; Chandler, Clayton

2015-06-01

Previous authors have suggested that Titan's individual sand particles form by either sintering or by lithification and erosion. We suggest two new mechanisms for the production of Titan's organic sand particles that would occur within bodies of liquid: flocculation and evaporitic precipitation. Such production mechanisms would suggest discrete sand sources in dry lakebeds. We search for such sources, but find no convincing candidates with the present Cassini Visual and Infrared Mapping Spectrometer coverage. As a result we propose that Titan's equatorial dunes may represent a single, global sand sea with west-to-east transport providing sources and sinks for sand in each interconnected basin. The sand might then be transported around Xanadu by fast-moving Barchan dune chains and/or fluvial transport in transient riverbeds. A river at the Xanadu/Shangri-La border could explain the sharp edge of the sand sea there, much like the Kuiseb River stops the Namib Sand Sea in southwest Africa on Earth. Future missions could use the composition of Titan's sands to constrain the global hydrocarbon cycle.

Wind-Driven Erosion and Exposure Potential at Mars 2020 Rover Candidate-Landing Sites

Science.gov (United States)

Chojnacki, Matthew; Banks, Maria; Urso, Anna

2018-01-01

Aeolian processes have likely been the predominant geomorphic agent for most of Mars’ history and have the potential to produce relatively young exposure ages for geologic units. Thus, identifying local evidence for aeolian erosion is highly relevant to the selection of landing sites for future missions, such as the Mars 2020 Rover mission that aims to explore astrobiologically relevant ancient environments. Here we investigate wind-driven activity at eight Mars 2020 candidate-landing sites to constrain erosion potential at these locations. To demonstrate our methods, we found that contemporary dune-derived abrasion rates were in agreement with rover-derived exhumation rates at Gale crater and could be employed elsewhere. The Holden crater candidate site was interpreted to have low contemporary erosion rates, based on the presence of a thick sand coverage of static ripples. Active ripples at the Eberswalde and southwest Melas sites may account for local erosion and the dearth of small craters. Moderate-flux regional dunes near Mawrth Vallis were deemed unrepresentative of the candidate site, which is interpreted to currently be experiencing low levels of erosion. The Nili Fossae site displayed the most unambiguous evidence for local sand transport and erosion, likely yielding relatively young exposure ages. The downselected Jezero crater and northeast Syrtis sites had high-flux neighboring dunes and exhibited substantial evidence for sediment pathways across their ellipses. Both sites had relatively high estimated abrasion rates, which would yield young exposure ages. The downselected Columbia Hills site lacked evidence for sand movement, and contemporary local erosion rates are estimated to be relatively low. PMID:29568719

Wind-Driven Erosion and Exposure Potential at Mars 2020 Rover Candidate-Landing Sites

Science.gov (United States)

Chojnacki, Matthew; Banks, Maria; Urso, Anna

2018-02-01

Aeolian processes have likely been the predominant geomorphic agent for most of Mars' history and have the potential to produce relatively young exposure ages for geologic units. Thus, identifying local evidence for aeolian erosion is highly relevant to the selection of landing sites for future missions, such as the Mars 2020 Rover mission that aims to explore astrobiologically relevant ancient environments. Here we investigate wind-driven activity at eight Mars 2020 candidate-landing sites to constrain erosion potential at these locations. To demonstrate our methods, we found that contemporary dune-derived abrasion rates were in agreement with rover-derived exhumation rates at Gale crater and could be employed elsewhere. The Holden crater candidate site was interpreted to have low contemporary erosion rates, based on the presence of a thick sand coverage of static ripples. Active ripples at the Eberswalde and southwest Melas sites may account for local erosion and the dearth of small craters. Moderate-flux regional dunes near Mawrth Vallis were deemed unrepresentative of the candidate site, which is interpreted to currently be experiencing low levels of erosion. The Nili Fossae site displayed the most unambiguous evidence for local sand transport and erosion, likely yielding relatively young exposure ages. The downselected Jezero crater and northeast Syrtis sites had high-flux neighboring dunes and exhibited substantial evidence for sediment pathways across their ellipses. Both sites had relatively high estimated abrasion rates, which would yield young exposure ages. The downselected Columbia Hills site lacked evidence for sand movement, and contemporary local erosion rates are estimated to be relatively low.

Fundamental study on cavitation erosion in liquid metal. Effect of liquid parameter on cavitation erosion in liquid metals (Joint research)

International Nuclear Information System (INIS)

Hattori, Shuji; Kurachi, Hiroaki; Inoue, Fumitaka; Watashi, Katsumi; Tsukimori, Kazuyuki; Yada, Hiroki; Hashimoto, Takashi

2009-02-01

Cavitation erosion, which possibly occurs on the surfaces of fluid machineries and components contacting flowing liquid and causes sponge-like damage on the material surface, is important problem, since it may become the cause of performance deduction, life shortening, noise, vibration of mechanical components and moreover failure of machine. Research on cavitation erosion in liquid metal is very important to confirm the safety of fast breeder reactor using sodium coolant and to avoid serious damage of the target vessel of spallation neutron source containing liquid-mercury. But the research on cavitation erosion in liquid metal has been hardly performed because of its specially in comparison with that in water. In this study, a cavitation erosion test apparatus was developed to carry out the erosion tests in low-temperature liquid metals. Cavitation erosion tests were carried out in liquid lead-bismuth alloy and in deionized water. We discuss the effect of liquid parameters and temperature effects on the erosion rate. We reach to the following conclusions. The erosion rate was evaluated in terms of a relative temperature which was defind as the percentage between freezing and boiling points. At 14degC relative temperature, the erosion rate is 10 times in lead-bismuth alloy, and 2 to 5 times in sodium, compared with that in deionized water. At 14degC relative temperature, the erosion rate can be evaluated in terms of the following parameter. 1 / (1/ρ L /C L +1/ρ S C S )√ρ L . Where ρ is the material density and c is the velocity of sound, L and S denote liquid and solid. In the relative temperature between 14 and 30degC, the temperature dependence on the erosion rate is due to the increase in vapor pressure. (author)

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

Wind driven erosion and the effects of particulate electrification

Science.gov (United States)

Merrison, J. P.; Bak, E.; Finster, K.; Gunnlaugsson, H. P.; Holstein-Rathlou, C.; Knak Jensen, S.; Nørnberg, P.; Rasmussen, K. R.

2012-09-01

Several related aspects of Aeolian activity are presently being studied in the laboratory, the most recent advances in this field will be presented. These include simulating wind driven erosion in the laboratory, quantifying erosion rates and the study of mineral change due to mechanical activation. Also advances in our understanding of the electrification of sand/dust particles is being made and how this phenomenon affects their behavior.

A 30000 yr record of erosion rates from cosmogenic 10Be in middle European river terraces

NARCIS (Netherlands)

Schaller, M.; Blanckenburg, von F.; Veldkamp, A.; Tebbens, L.A.; Hovius, N.; Kubik, P.W.

2002-01-01

Cosmogenic 10Be in river-borne quartz sand records a time-integrated erosion rate representative of an entire drainage basin. When sequestered in a terrace of known age, paleo-erosion rates may be recovered from the nuclide content of the terrace material. Paleo-erosion rates between 30 and 80

Sediment Transport and erosion modeling at Heaundae Beach in Korea.

Science.gov (United States)

Do, K.; Yoo, J.; McCall, R. T.

2016-12-01

The sand pocket beaches with two headlands are global features, but it's not easy to predict berm and dune erosion due to alongshore variation of water depth. This study investigates the sediment transport and morphological change using available wave and beach profile data, as well as to assess the applicability of the XBeach morphological model (Roelvink et al., 2009). The Haeundae is small pocket beach, 1.4 km long, located in the southern corner of the Korean Peninsula. The Korea Institute of Ocean Science and Technology (KIOST) measured beach profile along 27 survey lines. The beach profiles were surveyed five times from 17 June 2014 to 10 October 2014. For this duration, a wave gauge (AWAC) was installed at a depth about 23 m off the coast of Haeundae Beach. Severe four storms attacked Haeundae Beach for this duration and these storms lasted about 1 2 days with a peak significant wave height of 2.5 4.0 m. The placed sand is fairly sorted and its median diameter is 0.23 mm. 2DH coastal morphological model, XBeach developed to simulate dune erosion due to storm impacts. The model is based on the nonlinear shallow water equation and resolves nearshore hydrodynamics by employing a 2DH description of wave groups and infragravity motions. In this study, the numerical model XBeach was compared with the field data and used to estimate the sediment transport pattern on the sand pocket beach. The numerical model resulted in a comparable prediction in the west-part, but the east-part cannot reproduce the erosion and accretion of the sand, partly due to complex bathymetry and the lack of sediment. This limitation needs to be improved to use measured sand thickness data in future study

Alberta Reclamation Research annual report, 1990

International Nuclear Information System (INIS)

1991-01-01

The Reclamation Research Technical Advisory Committee (RRTAC) was appointed by the Alberta Land Conservation and Reclamation Council to assist in technical matters related to the development and administration of the Council's research program. RRTAC develops reclamation research under four major program areas, and activities in these areas during the year are described in this report. The Plains Coal Reclamation Research Program addresses questions relating to groundwater and soil reconstruction in plains coal mining zones. The Mountain and Foothills Reclamation Research Program focuses on water management, soil reconstruction, reforestation, and wildlife habitat development, with objectives including control of erosion on a variety of disturbances such as coal mines and ash pits. The Oil Sands Reclamation Research Program is attempting to develop techniques to establish self-sustaining, erosion-free cover on oil sand tailings pond dikes, and to return tailings sand storage and overburden dumps to productive forests. The Oil and Gas Reclamation Research Program is concerned with disposal of drilling wastes and reclamation of lands disturbed by oil and gas activities. Under each program, the objectives, basic problems investigated, and research approach are presented, followed by description of specific projects involving such subjects as hydrology, revegetation, soil-water interactions, landscape and watershed design, soil reconstruction and amendment, and soil compaction. A list of research reports is included. 69 refs., 8 figs

Simulation of erosion by a particulate airflow through a ventilator

Science.gov (United States)

Ghenaiet, A.

2015-08-01

Particulate flows are a serious problem in air ventilation systems, leading to erosion of rotor blades and aerodynamic performance degradation. This paper presents the numerical results of sand particle trajectories and erosion patterns in an axial ventilator and the subsequent blade deterioration. The flow field was solved separately by using the code CFX- TASCflow. The Lagrangian approach for the solid particles tracking implemented in our inhouse code considers particle and eddy interaction, particle size distribution, particle rebounds and near walls effects. The assessment of erosion wear is based on the impact frequency and local values of erosion rate. Particle trajectories and erosion simulation revealed distinctive zones of impacts with high rates of erosion mainly on the blade pressure side, whereas the suction side is eroded around the leading edge.

Fontainebleau Sand

DEFF Research Database (Denmark)

Leth, Caspar Thrane

2006-01-01

The report is a summary of results from laboratory tests in the geotechncial research group on Fontainebleau sand.......The report is a summary of results from laboratory tests in the geotechncial research group on Fontainebleau sand....

Rio Grande Lidar Bank Erosion Monitoring: Preliminary 2007-2008 Results and Survey Design Considerations

Science.gov (United States)

2010-09-01

was reexposed by erosion following the initial event (Figure 9). Erosion of the fan toe in the vicinity of the downstream array is primarily...Digitally Capture the Topography of Sand Dunes in High Spatial Resolution. Earth Surface Processes and Landforms 29:391-398. Queensland, G. 2008

Hydrogeological And Geotechnical Investigations Of Gully Erosion ...

African Journals Online (AJOL)

Consequently, hydrogeological and geotechnical studies of gully erosion sites were carried out in order to provide information on the genesis and continual expansion of gullies in the area. The results indicate that gullies are located in the upper aquifer of the Benin Formation (Coastal Plain Sands). The estimated hydraulic ...

Effects of disturbance on vegetation by sand accretion and erosion across coastal dune habitats on a barrier island.

Science.gov (United States)

Miller, Thomas E

2015-01-12

Coastal geomorphology and vegetation are expected to be particularly sensitive to climate change, because of disturbances caused by sea-level rise and increased storm frequency. Dunes have critical reciprocal interactions with vegetation; dunes create habitats for plants, while plants help to build dunes and promote geomorphological stability. These interactions are also greatly affected by disturbances associated with sand movement, either in accretion (dune building) or in erosion. The magnitude and intensity of disturbances are expected to vary with habitat, from the more exposed and less stable foredunes, to low-lying and flood-prone interdunes, to the protected and older backdunes. Permanent plots were established at three different spatial scales on St George Island, FL, USA, where the vegetation and dune elevation were quantified annually from 2011 to 2013. Change in elevation, either through accretion or erosion, was used as a measure of year-to-year disturbance over the 2 years of the study. At the scale of different dune habitats, foredunes were found to have the greatest disturbance, while interdunes had the least. Elevation and habitat (i.e. foredune, interdune, backdune) were significantly correlated with plant community composition. Generalized linear models conducted within each habitat show that the change in elevation (disturbance) is also significantly correlated with the plant community, but only within foredunes and interdunes. The importance of disturbance in exposed foredunes was expected and was found to be related to an increasing abundance of a dominant species (Uniola paniculata) in eroding areas. The significant effect of disturbance in the relatively stable interdunes was surprising, and may be due to the importance of flooding associated with small changes in elevation in these low-lying areas. Overall, this study documents changes in the plant community associated with elevation, and demonstrates that the foredune and interdune

Current research issues related to post-wildfire runoff and erosion processes

Science.gov (United States)

Moody, John A.; Shakesby, Richard A.; Robichaud, Peter R.; Cannon, Susan H.; Martin, Deborah A.

2013-01-01

Research into post-wildfire effects began in the United States more than 70 years ago and only later extended to other parts of the world. Post-wildfire responses are typically transient, episodic, variable in space and time, dependent on thresholds, and involve multiple processes measured by different methods. These characteristics tend to hinder research progress, but the large empirical knowledge base amassed in different regions of the world suggests that it should now be possible to synthesize the data and make a substantial improvement in the understanding of post-wildfire runoff and erosion response. Thus, it is important to identify and prioritize the research issues related to post-wildfire runoff and erosion. Priority research issues are the need to: (1) organize and synthesize similarities and differences in post-wildfire responses between different fire-prone regions of the world in order to determine common patterns and generalities that can explain cause and effect relations; (2) identify and quantify functional relations between metrics of fire effects and soil hydraulic properties that will better represent the dynamic and transient conditions after a wildfire; (3) determine the interaction between burned landscapes and temporally and spatially variable meso-scale precipitation, which is often the primary driver of post-wildfire runoff and erosion responses; (4) determine functional relations between precipitation, basin morphology, runoff connectivity, contributing area, surface roughness, depression storage, and soil characteristics required to predict the timing, magnitudes, and duration of floods and debris flows from ungaged burned basins; and (5) develop standard measurement methods that will ensure the collection of uniform and comparable runoff and erosion data. Resolution of these issues will help to improve conceptual and computer models of post-wildfire runoff and erosion processes.

Recent advances in phlebotomine sand fly research related to leishmaniasis control.

Science.gov (United States)

Bates, Paul A; Depaquit, Jerôme; Galati, Eunice A B; Kamhawi, Shaden; Maroli, Michele; McDowell, Mary Ann; Picado, Albert; Ready, Paul D; Salomón, O Daniel; Shaw, Jeffrey J; Traub-Csekö, Yara M; Warburg, Alon

2015-02-27

Phlebotomine sand flies are the subject of much research because of the role of their females as the only proven natural vectors of Leishmania species, the parasitic protozoans that are the causative agents of the neglected tropical disease leishmaniasis. Activity in this field was highlighted by the eighth International Symposium on Phlebotomine Sand flies (ISOPS) held in September 2014, which prompted this review focusing on vector control. Topics reviewed include: Taxonomy and phylogenetics, Vector competence, Genetics, genomics and transcriptomics, Eco-epidemiology, and Vector control. Research on sand flies as leishmaniasis vectors has revealed a diverse array of zoonotic and anthroponotic transmission cycles, mostly in subtropical and tropical regions of Africa, Asia and Latin America, but also in Mediterranean Europe. The challenge is to progress beyond descriptive eco-epidemiology, in order to separate vectors of biomedical importance from the sand fly species that are competent vectors but lack the vectorial capacity to cause much human disease. Transmission modelling is required to identify the vectors that are a public health priority, the ones that must be controlled as part of the integrated control of leishmaniasis. Effective modelling of transmission will require the use of entomological indices more precise than those usually reported in the leishmaniasis literature.

Experiments and Numerical Simulations of Dike Erosion due to a Wave Impact

Directory of Open Access Journals (Sweden)

Stefania Evangelista

2015-10-01

Full Text Available Dike erosion is a crucial issue in coastal and fluvial flood risk management. These defense structures appear vulnerable to extreme hydrological events, whose potential occurrence risk seems to be recently increased due to climate change. Their design and reinforcement is, however, a complex task, and although numerical models are very powerful nowadays, real processes cannot be accurately predicted; therefore, physical models constitute a useful tool to investigate different features under controlled conditions. This paper presents some laboratory experimental results of erosion of a sand dike produced by the impact of a dam break wave. Experiments have been conducted in the Water Engineering Laboratory at the University of Cassino and Southern Lazio, Italy, in a rectangular channel: here, the sudden opening of a gate forming the reservoir generates the wave impacting the dike, made in turn of two different, almost uniform sands. The physical evidence proves that the erosion process is strongly unsteady and significantly different from a gradual overtopping and highlights the importance of apparent cohesion for the fine sand dike. The experimental results have also been compared against the ones obtained through the numerical integration of a two-phase model, which shows the reasonable predictive capability of the temporal free surface and dike profile evolution.

Erosion of Earthen Levees by Wave Action

Science.gov (United States)

Ozeren, Y.; Wren, D. G.; Reba, M. L.

2016-02-01

Earthen levees of aquaculture and irrigation reservoirs in the United States often experience significant erosion due to wind-generated waves. Typically constructed using local soils, unprotected levees are subjected to rapid erosion and retreat due to wind generated waves and surface runoff. Only a limited amount of published work addresses the erosion rates for unprotected levees, and producers who rely on irrigation reservoirs need an economic basis for selecting a protection method for vulnerable levees. This, in turn, means that a relationship between wave energy and erosion of cohesive soils is needed. In this study, laboratory experiments were carried out in order to quantify wave induced levee erosion and retreat. A model erodible bank was packed using a soil consisting of approximately 14% sand, 73% silt, and 13% clay in a 20.6 m long 0.7 m wide and 1.2 m deep wave tank at the USDA-ARS, National Sedimentation Laboratory in Oxford MS. The geometry of the levee face was monitored by digital camera and the waves were measured by means of 6 capacitance wave staffs. Relationships were established between levee erosion, edge and retreat rates, and incident wave energy.

Weather resistance of CaSO4 ṡ 1/2H2O-based sand-fixation material

Science.gov (United States)

Liu, Xin; Tie, Shengnian

2017-07-01

Searching for an economical and effective sand-fixing material and technology is of great importance in Northwest China. This paper described the use of a semihydrated gypsum-(CaSO4 ṡ 1/2H2O-)based composite as a sand-fixing material. Its morphology and composition were characterized by SEM, and its water resistance, freezing-thawing resistance and wind erosion resistance were tested in the field. The results indicated that semihydrated gypsum-(CaSO4 ṡ 1/2H2O-)based sand-fixing composite has good water resistance and water-holding capacity. Its strength is maintained at 1.42 MPa after 50 freezing and thawing cycles, and its wind erosion increases with increasing wind speed and slope. Its compressive strength starts to decrease after nine months of field tests with no change in appearance, but it still satisfies the requirements of fixation technology. This sand-fixing material should have wide application owing to its good weather resistance.

Erosion resistance comparison of alternative surface treatments

Science.gov (United States)

Česánek, Z.; Schubert, J.; Houdková, Š.

2017-05-01

Erosion is a process characterized by the particle separation and the damage of component functional surfaces. Thermal spraying technology HP/HVOF (High Pressure / High Velocity Oxygen Fuel) is commonly used for protection of component surfaces against erosive wear. Alloy as well as cermet based coatings meet the requirements for high erosion resistance. Wear resistance is in many cases the determining property of required component functioning. The application suitability of coating materials is particularly influenced by different hardness. This paper therefore presents an erosion resistance comparison of alloy and cermet based coatings. The coatings were applied on steel substrates and were subjected to the erosive test using the device for evaluation of material erosion resistance working on the principle of centrifugal erodent flow. Abrasive sand Al2O3 with grain size 212-250 μm was selected as an erosive material. For this purpose, the specimens were prepared by thermal spraying technology HP/HVOF using commercially available powders Stellite 6, NiCrBSi, Cr3C2-25%NiCr, Cr3C2-25%CoNiCrAlY, Hastelloy C-276 and experimental coating TiMoCN-29% Ni. Erosion resistance of evaluated coatings was compared with erosive resistance of 1.4923 high alloyed steel without nitridation and in nitrided state and further with surface treatment using technology PVD. According to the evaluation, the resulting erosive resistance depends not only on the selected erodent and surface protection, but also on the erodent impact angle.

[Spatio-temporal change of sand-fixing function and its driving forces in desertification control ecological function area of Hunshandake, China].

Science.gov (United States)

Shen, Lu; Tian, Mei-rong; Gao, Ji-xi; Qian, Jin-ping

2016-01-01

Soil erosion is an important ecological and environmental problem in Hunshandake Desert, and the sand-fixing function determines the degree of ecological security in the entire region. In order to clarify the situation of windbreak and sand fixation in Hunshandake area, and to guide the prevention and treatment of desertification on regional scale, based on the meteorological and remote sensing data, this paper quantitatively analyzed the temporal and spatial pattern of windbreak and sand fixation ability between 2000-2010 by the revised wind erosion equation (RWEQ) model, meanwhile, the driving forces for each county ( or banner) in the functional zone were analyzed with the method of principal component analysis. The results showed that there was a fluctuation of the sand fixing capacity in Hunshandake over time, generally rendering a decline trend. The coniferous forest and grassland had strong windbreak and sand fixation capacity in unit area among the various land categories. In terms of spatial distribution, the windbreak and sand fixation function in western and southeastern region was weak and needed to be strengthened with ecological restoration efforts. Through the study of the social driving forces of each administrative region in the function zone, there were 3 main social driving forces of soil erosion in the administrative functions: the intensity of input-output, the level of economic development and the level of agriculture-husbandry development.

The National Wind Erosion Research Network: Building a standardized long-term data resource for aeolian research, modeling and land management

Science.gov (United States)

Webb, Nicholas P.; Herrick, Jeffrey E.; Van Zee, Justin W; Courtright, Ericha M; Hugenholtz, Ted M; Zobeck, Ted M; Okin, Gregory S.; Barchyn, Thomas E; Billings, Benjamin J; Boyd, Robert A.; Clingan, Scott D; Cooper, Brad F; Duniway, Michael C.; Derner, Justin D.; Fox, Fred A; Havstad, Kris M.; Heilman, Philip; LaPlante, Valerie; Ludwig, Noel A; Metz, Loretta J; Nearing, Mark A; Norfleet, M Lee; Pierson, Frederick B; Sanderson, Matt A; Sharrat, Brenton S; Steiner, Jean L; Tatarko, John; Tedela, Negussie H; Todelo, David; Unnasch, Robert S; Van Pelt, R Scott; Wagner, Larry

2016-01-01

The National Wind Erosion Research Network was established in 2014 as a collaborative effort led by the United States Department of Agriculture’s Agricultural Research Service and Natural Resources Conservation Service, and the United States Department of the Interior’s Bureau of Land Management, to address the need for a long-term research program to meet critical challenges in wind erosion research and management in the United States. The Network has three aims: (1) provide data to support understanding of basic aeolian processes across land use types, land cover types, and management practices, (2) support development and application of models to assess wind erosion and dust emission and their impacts on human and environmental systems, and (3) encourage collaboration among the aeolian research community and resource managers for the transfer of wind erosion technologies. The Network currently consists of thirteen intensively instrumented sites providing measurements of aeolian sediment transport rates, meteorological conditions, and soil and vegetation properties that influence wind erosion. Network sites are located across rangelands, croplands, and deserts of the western US. In support of Network activities, http://winderosionnetwork.org was developed as a portal for information about the Network, providing site descriptions, measurement protocols, and data visualization tools to facilitate collaboration with scientists and managers interested in the Network and accessing Network products. The Network provides a mechanism for engaging national and international partners in a wind erosion research program that addresses the need for improved understanding and prediction of aeolian processes across complex and diverse land use types and management practices.

Sand wave fields beneath the Loop Current, Gulf of Mexico: Reworking of fan sands

Science.gov (United States)

Kenyon, Neil H.; Akhmetzhanov, A.M.; Twichell, D.C.

2002-01-01

Extensive fields of large barchan-like sand waves and longitudinal sand ribbons have been mapped by deep-towed SeaMARC IA sidescan sonar on part of the middle and lower Mississippi Fan that lies in about 3200 m of water. The area is beneath the strongly flowing Loop Current. The bedforms have not been adequately sampled but probably consist of winnowed siliciclastic-foraminiferal sands. The size (about 200 m from wingtip to wingtip) and shape of the large barchans is consistent with a previously observed peak current speed of 30 cm/s, measured 25 m above the seabed. The types of small-scale bedforms and the scoured surfaces of chemical crusts, seen on nearby bottom photographs, indicate that near-bed currents in excess of 30 cm/s may sometimes occur. At the time of the survey the sand transport direction was to the northwest, in the opposite direction to the Loop Current but consistent with there being a deep boundary current along the foot of the Florida Escarpment. Some reworking of the underlying sandy turbidites and debris flow deposits is apparent on the sidescan sonar records. Reworking by deep-sea currents, resulting in erosion and in deposits characterised by coarsening upwards structures and cross-bedding, is a process that has been proposed for sand found in cores in shallower parts of the Gulf of Mexico. This process is more widespread than hitherto supposed. 

Predicting Effects of Corrosion Erosion of High Strength Steel Pipelines Elbow on CO2-Acetic Acid (HAc) Solution

International Nuclear Information System (INIS)

Asmara, Y. P.; Ismail, M. F.; Chui, L. Giok; Halimi, Jamiludin

2016-01-01

Simultaneously effect of erosion combined with corrosion becomes the most concern in oil and gas industries. It is due to the fast deterioration of metal as effects of solid particles mixed with corrosive environment. There are many corrosion software to investigate possible degradation mechanisms developed by researchers. They are using many combination factors of chemical reactions and physical process. However effects of CO 2 and acid on pipelines orientations are still remain uncovered in their simulation. This research will investigate combination effects of CO 2 and HAc on corrosion and erosion artificial environmental containing sands particles in 45°, 90° and 180° elbow pipelines. The research used theoretical calculations combined with experiments for verification. The main concerns are to investigate the maximum erosion corrosion rate and maximum shear stress at the surface. Methodology used to calculate corrosion rate are Linear Polarization Resistance (LPR) and weight loss. The results showed that at 45°, erosion rate is the more significant effects in contributing degradation of the metal. The effects of CO 2 and HAc gave significant effects when flow rate of the solution are high which reflect synergism effects of solid particles and those chemical compositions. (paper)

Tooth wear and erosion: methodological issues in epidemiological and public health research and the future research agenda.

Science.gov (United States)

Ganss, C; Young, A; Lussi, A

2011-09-01

This paper addresses methodological issues in the field of tooth wear and erosion research including the epidemiological indices, and identifies future work that is needed to improve knowledge about tooth wear and erosion. The paper is result of the work done at the meetings of the Special Interest Group "Tooth Surface Loss and Erosion" at the 2008, 2009 and 2010 conferences of the European Association for Dental Public Health, and the Workshop "Current Erosion indices- flawed or valid" which took place in Basel in 2007. Although there is consensus about the definition and the diagnostic criteria of various forms of tooth wear, gaps in research strategies have been identified. A basic problem is that fundamental concepts of wear and erosion as an oral health problem, have not yet been sufficiently defined. To a certain extent, tooth wear is a physiological condition, and there is no consensus as to whether it can be regarded as a disease. Furthermore, the multitude of indices and flaws in existing indices, make published data difficult to interpret. Topics for the research agenda are: the initiation of a consensus process towards an internationally accepted index, and the initiation of data collection on the prevalence of various forms of wear on a population-based level. There should be an emphasis on promoting communication between basic and clinical sciences, and the area of Public Health Dentistry. Furthermore, the question of whether tooth wear is a public health problem remains open for debate.

Slurry Erosion Behavior of Destabilized and Deep Cryogenically Treated Cr-Mn-Cu White Cast Irons

Directory of Open Access Journals (Sweden)

S. Gupta

2016-12-01

Full Text Available The effects of destabilization treatment and destabilization followed by cryogenic treatment have been evaluated on the microstructural evolution and sand-water slurry erosion behavior of Cr-Mn-Cu white cast irons. The phase transformations after the destabilization and cryotreatment have been characterized by bulk hardness measurement, optical and scanning electron microscopy, x-ray diffraction analysis. The static corrosion rate has been measured in tap water (with pH=7 and the erosion-corrosion behavior has been studied by slurry pot tester using sand-water slurry. The test results indicate that the cryogenic treatment has a significant effect in minimizing the as-cast retained austenite content and transforming into martensitic and bainitic matrix embedded with ultra-fine M7C3 alloy carbides. In contrast, by conventional destabilization treatment retained austenite in the matrix are not fully eliminated. The slurry erosive wear resistance has been compared with reference to destabilized and cryotreated high chromium iron samples which are commonly employed for such applications. The cryotreated Cr-Mn-Cu irons have exhibited a comparable erosive wear performance to those of high chromium irons. Higher hardness combined with improved corrosion resistance result in better slurry erosion resistance.

Sand spit and shoreline dynamics near Terekhol river mouth, Goa, India

Digital Repository Service at National Institute of Oceanography (India)

Rajasekaran, C.; Jayakumar, S.; Gowthaman, R.; Jishad, M.; Yadhunath, E.M.; Pednekar, P.S.

Evolution of shoreline and sand spit at the mouth of the Terekhol River, near Keri beach, located in the Indian state of Goa has been investigated From the analysis of the data collected, the shoreline oscillation (accretion & erosion) is seasonal...

Erosion Corrosion and Protection of Recycle System with Seawater

Directory of Open Access Journals (Sweden)

Xue Jin

2016-01-01

Full Text Available In order to investigate the corrosion of recycle system with seawater in rights of power plant, the erosion behavior and mechanism of erosion corrosion in this system constructed with several corrosionresistance alloys have been studied and tested in the condition of high speed fluid with a sand particles. Both special protection technologies and results, one designed by high temperature epoxy resin powder coating and another of the associating method of anode protection together with such same coating, have been discussed as well in this case.

Wind born(e) landscapes: the role of wind erosion in agricultural land management and nature development

NARCIS (Netherlands)

Riksen, M.J.P.M.

2006-01-01

Wind has played an important role in the geological development of the north-western Europe. Various aeolian deposits such as inland dunes, river dunes, cover sands, drift sands and coastal dunes, form the base of large areas in our present landscape. The role of wind erosion in today's north-west

Erosion-corrosion synergistics in the low erosion regime

International Nuclear Information System (INIS)

Corey, R.G.; Sethi, V.K.

1986-01-01

Many engineering alloys display good high temperature corrosion resistance. However, when they are used in corrosive environments where they are subjected to erosion also, the corrosion resistance has been adversely affected. The phenomenon known as erosion-corrosion is complex and requires detailed investigation of how the erosion and corrosion kinetics interact and compete. At the Kentucky Center for Energy Research Laboratory, an erosion-corrosion tester was used to perform erosion-oxidation tests on 2 1/4 Cr-1 Mo steel at 500-600 0 C using alumina abrasive at low velocities. The erosion-oxidation rate data and morphology of exposed surfaces are consistent with oxide chipping and fracturing being the mode of material loss

Dark grains of sand: a geological storytelling

Science.gov (United States)

Gallo Maresca, Magda

2017-04-01

In the secondary Italian school the Earth science learning begins at first year, in synergy with other natural science subjects such as Astronomy, Chemistry and Biology. Italian teachers have to focus on the landscape geomorphological aspects and often Earth processes are difficult to display since they are related to certain phenomena happened during the past and often far from the involved country. In order to better understand the environment surrounding us, very simple and poor materials, like sands, allow the teachers to create attractive lab experiences. According to the IBSE (Inquiry Based Science Education) approach, a learning unit has been implemented starting from a walking along the light carbonate beaches of the Adriatic sea: a smart look to the sands ("engage step"), stroke the students fantasy pushing them to explore some strange black grains on the sands. Dirty sands? Or rock landscape, soil degradation and Ofanto river and coastal processes (erosion, transportation and deposition)? This was the teaching challenge. Due to the youngest age, a third level, guided inquiry, was adopted so the teacher is the "guide of inquiry" encouraging the students using the research question ("Why is the sand dark?", "Do all sands look the same?", "Where does it come from?") and driving the students around their investigation plans ("How can I measure grain size?"). A procedure to answer the above questions and validate the results and explanations has been implemented to allow the students to be proactive in their study. During the learning activities will be the students to ask for field trip to elaborate their new knowledge, verify and visualize the speculated processes. The teaching skills allow to address several geosciences domains such as mineralogy, petrology, regional geology and geodynamics as well as other scientific disciplines such as mathematics (more specifically statistics), forensic science and even life sciences (the presence of bioclasts might

Reports on 1974 result of Sunshine Project. Research on tar sand and oil shale; 1974 nendo tar sand oyobi oil shale ni kansuru chosa kenkyu seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1975-04-04

The purpose of this research is to grasp the policy of the oil sand resource countries, the properties and existing conditions of the resources, effects of the oil sand resources on a long term energy supply/demand, etc., and to clarify the meaning and position of the researches on the development of oil sand resources in the future energy policy of Japan. The quantities of oil sand resources are mostly in the process of investigation except Alberta province of Canada and are estimated to be two trillion barrels. The quantity for which strip mining is possible is about 90 billion barrels, which are mostly located in the Athabasca region. The oil sand holding countries take a policy of positively developing oil sand. No barriers are particularly provided against the introduction of foreign technology and capital. Where the prospects are possible for the development of oil sand are Canada and Venezuela. R and D should be emphasized on the refining of bitumen and the extraction method within the oil reservoir. The investment per b/d is about 15-20 thousand dollars, which is likely to be more than twice as much as for the North Sea oilfields. The properties and quality of the synthetic crude oil are superior while the risk of exploitation is small; therefore, oil sand will be competitive with crude oil in the future. (NEDO)

Solid Particle Erosion of Date Palm Leaf Fiber Reinforced Polyvinyl Alcohol Composites

Directory of Open Access Journals (Sweden)

Jyoti R. Mohanty

2014-01-01

Full Text Available Solid particle erosion behavior of short date palm leaf (DPL fiber reinforced polyvinyl alcohol (PVA composite has been studied using silica sand particles (200 ± 50 μm as an erodent at different impingement angles (15–90° and impact velocities (48–109 m/s. The influence of fiber content (wt% of DPL fiber on erosion rate of PVA/DPL composite has also been investigated. The neat PVA shows maximum erosion rate at 30° impingement angle whereas PVA/DPL composites exhibit maximum erosion rate at 45° impingement angle irrespective of fiber loading showing semiductile behavior. The erosion efficiency of PVA and its composites varies from 0.735 to 16.289% for different impact velocities studied. The eroded surfaces were observed under scanning electron microscope (SEM to understand the erosion mechanism.

Post-wildfire soil erosion in the Mediterranean: Review and future research directions

Science.gov (United States)

Shakesby, R. A.

2011-04-01

Wildfires increased dramatically in frequency and extent in the European Mediterranean region from the 1960s, aided by a general warming and drying trend, but driven primarily by socio-economic changes, including rural depopulation, land abandonment and afforestation with flammable species. Published research into post-wildfire hydrology and soil erosion, beginning during the 1980s in Spain, has been followed by studies in other European Mediterranean countries together with Israel and has now attained a sufficiently large critical mass to warrant a major review. Although variations in climate, vegetation, soil, topography and fire severity cause differences in Mediterranean post-wildfire erosion, the long history of human landscape impact up to the present day is responsible for some its distinctive characteristics. This paper highlights these characteristics in reviewing wildfire impacts on hydrology, soil properties and soil erosion by water. The 'mosaic' nature of many Mediterranean landscapes (e.g. an intricate land-use pattern, abandoned terraces and tracks interrupting slopes) may explain sometimes conflicting post-fire hydrological and erosional responses at different sites and spatial scales. First-year post-wildfire soil losses at point- (average, 45-56 t ha - 1 ) and plot-scales (many Aspect is important, with more erosion reported for south- than north-facing slopes, which is attributed to greater fire frequency, slower vegetation recovery on the former and with soil characteristics more prone to erosion (e.g. lower aggregate stability). Post-fire wind erosion is a potentially important but largely neglected process. Gauging the degradational significance of wildfires has relied on comparison with unburnt land, but the focus for comparison should be switched to other agents of soil disturbance and/or currently poorly understood soil renewal rates. Human impact on land use and vegetation may alter expected effects (increased fire activity and post

Active Anti-erosion Protection Strategy in Tamarisk (Tamarix aphylla)

Science.gov (United States)

Han, Zhiwu; Yin, Wei; Zhang, Junqiu; Niu, Shichao; Ren, Luquan

2013-12-01

Plants have numerous active protection strategies for adapting to complex and severe environments. These strategies provide endless inspiration for extending the service life of materials and machines. Tamarisk (Tamarix aphylla), a tree that thrives in raging sandstorm regions, has adapted to blustery conditions by evolving extremely effective and robust erosion resistant characteristics. However, the relationships among its surface cracks, internal histology and biomechanics, such as cracks, rings, cells, elasticity modulus and growth stress, which account for its erosion resistance, remain unclear. This present study reveals that the directionally eccentric growth rings of tamarisk, which are attributed to reduced stress and accelerated cell division, promote the formation of surface cracks. The windward rings are more extensive than the leeward side rings. The windward surfaces are more prone to cracks, which improves erosion resistance. Our data provide insight into the active protection strategy of the tamarisk against wind-sand erosion.

Coastal erosion management in Accra: Combining local knowledge and empirical research

Directory of Open Access Journals (Sweden)

Kwasi Appeaning Addo

2016-11-01

Full Text Available Coastal erosion along the Accra coast has become a chronic phenomenon that threatens both life and property. The issue has assumed a centre stage of national debate in recent times because of its impact on the coastal communities. Lack of reliable geospatial data hinders effective scientific investigations into the changing trends in the shoreline position. However, knowledge about coastal erosion, by the local people, and how far the shoreline has migrated inland over time is high in the coastal communities in Accra. This opens a new chapter in coastal erosion research to include local knowledge of the local settlers in developing sustainable coastal management. This article adopted a scientific approach to estimate rate of erosion and tested the results against perceived erosion trend by the local settlers. The study used a 1974 digital topographic map and 1996 aerial photographs. The end point rate statistical method in DSAS was used to compute the rates of change. The short-term rate of change for the 22-year period under study was estimated as -0.91 m/annum ± 0.49 m/annum. It was revealed that about 79% of the shoreline is eroding, while the remaining 21% is either stabilised or accreting. It emerged, from semi-structured interviews with inhabitants in the Accra coastal communities, that an average of about 30 m of coastal lands are perceived to have been lost to erosion for a period of about 20 years. This translates to a historic rate of change of about 1.5 m/year, which corroborates the results of the scientific study. Again this study has established that the local knowledge of the inhabitants, about coastal erosion, can serve as reliable information under scarcity of scientific data for coastal erosion analyses in developing countries.

Soil erosion and degradation in Mediterranean Type Ecosystems. The Soil Erosion and Degradation Research Group (SEDER) approach and findings

Science.gov (United States)

Cerdà, Artemi; Keesstra, Saskia; Pulido, Manuel; Jordán, Antonio; Novara, Agata; Giménez-Morera, Antonio; Borja, Manuel Esteban Lucas; Francisco Martínez-Murillo, Juan; Rodrigo-Comino, Jesús; Pereira, Paulo; Nadal-Romero, Estela; Taguas, Tani; Úbeda, Xavier; Brevik, Eric C.; Tarolli, Paolo; Bagarello, Vicenzo; Parras Alcantara, Luis; Muñoz-Rojas, Miriam; Oliva, Marc; di Prima, Simone

2017-04-01

The Soil Erosion and Degradation Reseach Group (SEDER) is developing a research program since 2002 to assess the soil erosion and degradation processes at the Canyoles River watershed in Eastern Spain. The research study site was selected as representative of the environmental changes that take place in the Mediterranean: abandonment of the agriculture land in the mountains, forest fire expansion, intensification of the agriculture, impact of the infraesturctures such as rail and road embankments, and soil sealing due to the urban expansion. The research is based on the continuous measurements in the Montesa and El Teularet research stations and the sampling of the soils, topographical measurements and the use of rainfall simulators, minidisk infiltrometers, ring infiltrometers and Water Drop Penetration Time tests. The research is moving from a pure scientific approach to a more socio-economic view, and the stakeholders are being researched from a perception point of view. SEDER is also moving from pure to applied science, with the objective to design new managements that will satisfy the stakeholders and will achieve the sustainability. The research is being carried out in vineyards and orchards as they show extremely high erosion rates. But also we are interested in the impact of forest fires and the road embankments. In all three research topics, SEDER wish to find the sustainable managements. Acknowledgements The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 603498 (RECARE project) and the CGL2013- 47862-C2-1-R and CGL2016-75178-C2-2-R national research projects. References Bodí, M. B., Martin, D. A., Balfour, V. N., Santín, C., Doerr, S. H., Pereira, P., . . . Mataix-Solera, J. (2014). Corrigendum to "wildland fire ash: Production, composition and eco-hydro-geomorphic effects", earth sci. rev. 130 (2014) [103-127]. Earth-Science Reviews, 138, 503. doi:10

The importance of sand in the formation of avulsion channels within experimental fans that develop from sediment mixtures of mud and sand

Science.gov (United States)

Iscen, N.; Strom, K.

2017-12-01

Autogenic channel migration and avulsion has long been recognized as important drivers of alluvial fan dynamics. In the literature, several field studies have documented that the presence and the amount of sand transport through a channel is important for channel incision in alluvial fans and deltas. In our experiments, we present the general autogenic avulsion cycle of experimental alluvial fans with mixtures of cohesive sediment and sand with a range of boundary conditions, and we detail the importance of mobile sand fraction in the development of channels that lead to avulsion. Experimental observations demonstrate that new channels form at topographically low regions within the floodplain providing that sand is transported to these topographic lows due to overbank flow or levee breaching. In addition to the sediment transported from upstream, erosion of a previous deposit and an ongoing backfilling nearby are observed as the possible sources of sand getting into the ghost channels. We explore whether the presence of sand is important for channel development because it increases abrasion of the channel or because it changes the roughness characteristics of the flow. We also examine the affect of sediment and water supply change on the newly described channelization process and link distinctive channel morphologies to different stages of described channel development and the avulsion process.

The Effect of Air Density on Sand Transport Structures and the Adobe Abrasion Profile: A Field Wind-Tunnel Experiment Over a Wide Range of Altitude

Science.gov (United States)

Han, Qingjie; Qu, Jianjun; Dong, Zhibao; Zu, Ruiping; Zhang, Kecun; Wang, Hongtao; Xie, Shengbo

2014-02-01

Aeolian sand transport results from interactions between the surface and the airflow above. Air density strongly constrains airflow characteristics and the resulting flow of sand, and therefore should not be neglected in sand transport models. In the present study, we quantify the influence of air density on the sand flow structure, sand transport rate, adobe abrasion profiles, and abrasion rate using a portable wind-tunnel in the field. For a given wind speed, the flow's ability to transport sand decreases at low air density, so total sand transport decreases, but the saltation height increases. Thus, the damage to human structures increases compared with what occurs at lower altitudes. The adobe abrasion rate by the cloud of blowing sand decreases exponentially with increasing height above the surface, while the wind erosion and dust emission intensity both increase with increasing air density. Long-term feedback processes between air density and wind erosion suggest that the development of low-altitude areas due to long-term deflation plays a key role in dust emission, and will have a profound significance for surface Aeolian processes and geomorphology.

An Extreme Event as a Game Changer in Coastal Erosion Management

DEFF Research Database (Denmark)

Sørensen, Carlo Sass; Drønen, Nils K.; Knudsen, Per

2016-01-01

of cyclone Xaver in December 2013 with severe coastal erosion led to collaboration between the involved municipalities to work on a coherent solution for the entire coastline that involves sand nourishments, renovation and optimization of hard protection structures, and the restoration of recreational values...

Corrosion and erosion properties of silicate and phosphate coatings on magnesium

International Nuclear Information System (INIS)

Ma, Y.; Nie, X.; Northwood, D.O.; Hu, H.

2004-01-01

Electrolytic plasma processing (EPP) is an emerging, environmentally friendly, surface engineering technique. In this study, we have utilized the EPP technique to deposit silicate and phosphate coatings on magnesium for both corrosion and erosion protection. Potentiodynamic polarization measurements were used to investigate the corrosion properties of the coated samples. A stirring device was also used for corrosion and erosion testing. Coated and uncoated samples were immersed in a 3.5 wt.% NaCl solution with SiO 2 sand in suspension and rotated at a given speed. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis were used to study surface morphology and chemical composition of the coatings before and after corrosion-erosion testing

Coastal geology and recent origins for Sand Point, Lake Superior

Science.gov (United States)

Fisher, Timothy G.; Krantz, David E.; Castaneda, Mario R.; Loope, Walter L.; Jol, Harry M.; Goble, Ronald J.; Higley, Melinda C.; DeWald, Samantha; Hansen, Paul

2014-01-01

Sand Point is a small cuspate foreland located along the southeastern shore of Lake Superior within Pictured Rocks National Lakeshore near Munising, Michigan. Park managers’ concerns for the integrity of historic buildings at the northern periphery of the point during the rising lake levels in the mid-1980s greatly elevated the priority of research into the geomorphic history and age of Sand Point. To pursue this priority, we recovered sediment cores from four ponds on Sand Point, assessed subsurface stratigraphy onshore and offshore using geophysical techniques, and interpreted the chronology of events using radiocarbon and luminescence dating. Sand Point formed at the southwest edge of a subaqueous platform whose base is probably constructed of glacial diamicton and outwash. During the post-glacial Nipissing Transgression, the base was mantled with sand derived from erosion of adjacent sandstone cliffs. An aerial photograph time sequence, 1939–present, shows that the periphery of the platform has evolved considerably during historical time, infl uenced by transport of sediment into adjacent South Bay. Shallow seismic refl ections suggest slump blocks along the leading edge of the platform. Light detection and ranging (LiDAR) and shallow seismic refl ections to the northwest of the platform reveal large sand waves within a deep (12 m) channel produced by currents fl owing episodically to the northeast into Lake Superior. Ground-penetrating radar profi les show transport and deposition of sand across the upper surface of the platform. Basal radiocarbon dates from ponds between subaerial beach ridges range in age from 540 to 910 cal yr B.P., suggesting that Sand Point became emergent during the last ~1000 years, upon the separation of Lake Superior from Lakes Huron and Michigan. However, optically stimulated luminescence (OSL) ages from the beach ridges were two to three times as old as the radiocarbon ages, implying that emergence of Sand Point may have begun

Tools for Ephemeral Gully Erosion Process Research

Science.gov (United States)

Techniques to quantify ephemeral gully erosion have been identified by USDA Natural Resources Conservation Service (NRCS) as one of gaps in current erosion assessment tools. One reason that may have contributed to this technology gap is the difficulty to quantify changes in channel geometry to asses...

Erosion of magnesium potassium phosphate ceramic waste forms

International Nuclear Information System (INIS)

Goretta, K. C.

1998-01-01

Phosphate-based chemically bonded ceramics were formed from magnesium potassium phosphate (MKP) binder and either industrial fly ash or steel slag. The resulting ceramics were subjected to solid-particle erosion by a stream of either angular Al 2 O 3 particles or rounded SiO 2 sand. Particle impact angles were 30 or 90degree and the impact velocity was 50 m/s. Steady-state erosion rates, measured as mass lost from a specimen per mass of impacting particle, were dependent on impact angle and on erodent particle size and shape. Material was lost by a combination of fracture mechanisms. Evolution of H 2 O from the MKP phase appeared to contribute significantly to the material loss

Erosion by rain in the western Congo

International Nuclear Information System (INIS)

Ploey, J. de

1967-01-01

Vast expanses of the western part of central and southern Africa are covered with uniform, sandy formations of the Kalahari type. The topography of these areas and their present morphological characteristics are mainly the result of erosion by rain. Information on the hydrology of the surface waters in these areas is fairly limited and is insufficient to permit any conclusions regarding the way in which erosion by rain takes place. To obtain a better understanding of these phenomena, the author devised a series of experiments based on the use of 46 Sc-labelled radioactive sand. These experiments began at the beginning of the 1964/65 rainy season and are continuing. The experimental plot corresponds to convex and rectilinear portions of a hillside with a slope varying between 0 and 12 degrees. The vegetation consists of grassy savannah of substeppe appearance and secondary forests. Series of labelled samples were placed successively on the surface of the experimental plot and the erosive effect of rain was determined by measuring the residual concentrations after rainfall. Some samples were placed below a shield so as to eliminate the effects of splash and reveal the part played by runoff. Radiographic films were used to study the dispersion of labelled particles in the surrounding area. This radiographic method made it possible to determine the scale of erosion by splash for different rainfall conditions. The erosion diagrams obtained from these experiments show the correlations that exist between the intensity and duration of the rainfall and the erosion of the soil. Examination of the erosion diagrams and the shielded samples and analysis of the radiographs showed that erosion by rain on Kalahari ground covered with substeppe savannah is caused mainly by splash erosion and by dispersed, intermittent runoff. Sheet wash plays no part if the slope is less than 12 degrees. (author) [fr

Influence of Geometric Parameters of the Hydrocyclone and Sand Concentration on the Water/Sand/Heavy-Oil Separation Process: Modeling and Simulation

Directory of Open Access Journals (Sweden)

F Farias

2016-09-01

Full Text Available In the oil exploitation, produced fluids are composed of oil, gas, water and sand (depending on the reservoir location. The presence of sand in flow oil leads to several industrial problems for example: erosion and accumulation in valves and pipeline. Thus, it is necessary to stop production for manual cleaning of equipments and pipes. These facts have attracted attention of academic and industrial areas, enabling the appearing of new technologies or improvement of the water/oil/sand separation process. One equipment that has been used to promote phase separation is the hydrocyclone due to high performance of separation and required low cost to installation and maintenance. In this sense, the purpose of this work is to study numerically the effect of geometric parameters (vortex finder diameter of the hydrocyclone and sand concentration on the inlet fluid separation process. A numerical solution of the governing equations was obtained by the ANSYS CFX-11 commercial code. Results of the streamlines, pressure drop and separation efficiency on the hydrocyclone are presented and analyzed. It was observed that the particles concentration and geometry affect the separation efficiency of the hydrocyclone.

Research and information needs for management of tar sands development. Interim report Apr-May 83

Energy Technology Data Exchange (ETDEWEB)

1983-05-01

The report discusses important research and information needs for federal lease management of lands with tar sands resources. Short-term needs include more complete definition and characterization of deposits, hydrology, and regions downwind from tar sands areas. Longer-term needs include demonstration-scale operations to resolve production, waste management, and reclamation problems and to provide opportunities for measurement, analysis, and assessment of mining and processing wastes and emissions. Most of the known federal tar sands resource is in eastern Utah and contains about 25 billion barrels of bitumen. Recent legislation provides that existing mining claims and oil and gas leases may be converted to combined hydrocarbon leases including tar sands. Federal approval, which must be applied for by November 1983, is a condition for conversion.

The Alberta oil sands story

Energy Technology Data Exchange (ETDEWEB)

1974-01-01

This report serves as a detailed introduction to the Alberta oil sands and their development. It includes a description of the oil sands deposits, an outline of crude bitumen recovery and upgrading processes, the role of Alberta Energy Company in oil sands development, environmental aspects, manpower requirements for oil sands development, research needs, and further oil sands projects. Presently proven recoverable reserves in the oil sands amount to 26.5 billion bbl of synthetic crude. Production from the Syncrude plant (125,000 bbl/d capacity) is expected to begin in 1977, followed by a Shell Canada operation around 1980. The provincial government will participate in the oil sand industry through its joint venture participation in Syncrude and its 50% share in Alberta Energy Company; the latter company participates in related aspects of the Syncrude project, such as pipelines. The result of Alberta's participation in the industry will mean that, directly or indirectly, the province will realize 60% of the total profits. The job creation potential of oil sands projects is estimated to be extensive, with a direct and indirect work force supported by oil sands activities possibly reaching 180,000 persons by the year 2000. Research needs have been identified, particularly in the area of in-situ thermal recovery technology, and the creation of the Alberta Oil Sands Technology and Research Authority has been authorized in order to meet these needs. Although current reserves are sufficient to support 20-30 synthetic crude plants, a number of factors will limit expansion of the industry. 8 figs., 5 tabs.

Field Evaluation/Demonstration of a Multisegmented Dewatering System for Accreting Beach Sand in a High-Wave-Energy Environment

National Research Council Canada - National Science Library

Curtis, William

1998-01-01

This study documents the use of beach dewatering systems to accrete beach sand and minimize erosion, and to develop quantitative guidance for constructing and operating beach dewatering installations...

Development and Life Prediction of Erosion Resistant Turbine Low Conductivity Thermal Barrier Coatings

Science.gov (United States)

Zhu, Dongming; Miller, Robert A.; Kuczmarski, Maria A.

2010-01-01

Future rotorcraft propulsion systems are required to operate under highly-loaded conditions and in harsh sand erosion environments, thereby imposing significant material design and durability issues. The incorporation of advanced thermal barrier coatings (TBC) in high pressure turbine systems enables engine designs with higher inlet temperatures, thus improving the engine efficiency, power density and reliability. The impact and erosion resistance of turbine thermal barrier coating systems are crucial to the turbine coating technology application, because a robust turbine blade TBC system is a prerequisite for fully utilizing the potential coating technology benefit in the rotorcraft propulsion. This paper describes the turbine blade TBC development in addressing the coating impact and erosion resistance. Advanced thermal barrier coating systems with improved performance have also been validated in laboratory simulated engine erosion and/or thermal gradient environments. A preliminary life prediction modeling approach to emphasize the turbine blade coating erosion is also presented.

Sediment volume in the north polar sand seas of Mars

International Nuclear Information System (INIS)

Lancaster, N.; Greeley, R.

1990-01-01

Data from studies of the cross-sectional area of terrestrial transverse dunes have been combined with maps of dune morphometry derived from Viking orbiter images to generate new estimates of sediment thickness and dune sediment volume in the north polar sand seas of Mars. A relationship between dune spacing and equivalent sediment thickness (EST) was developed from field data on Namibian and North American dunes and was applied to data on dune spacing and dune cover measured on Viking orbiter images to generate maps of dune sediment thickness for Martian north polar sand seas. There are four major sand seas in the north polar region of Mars, covering an area of 6.8 x 10 5 km 2 . Equivalent sediment thickness ranges between 0.5 and 6.1 m with a mean of 1.8 m. The sand seas contain a total of 1158 km 3 of dune sediment, which may have been derived by erosion of polar layered deposits and concentrated in its present location by winds that change direction seasonally

Erosion of magnesium potassium phosphate ceramic waste forms.

Energy Technology Data Exchange (ETDEWEB)

Goretta, K. C.

1998-11-20

Phosphate-based chemically bonded ceramics were formed from magnesium potassium phosphate (MKP) binder and either industrial fly ash or steel slag. The resulting ceramics were subjected to solid-particle erosion by a stream of either angular Al{sub 2}O{sub 3} particles or rounded SiO{sub 2} sand. Particle impact angles were 30 or 90{degree} and the impact velocity was 50 m/s. Steady-state erosion rates, measured as mass lost from a specimen per mass of impacting particle, were dependent on impact angle and on erodent particle size and shape. Material was lost by a combination of fracture mechanisms. Evolution of H{sub 2}O from the MKP phase appeared to contribute significantly to the material loss.

Elevated temperature erosion studies on some materials for high temperature applications

International Nuclear Information System (INIS)

Zhou Jianren.

1991-01-01

The surface degradation of materials due to high temperature erosion or combined erosion corrosion is a serious problem in many industrial and aeronautical applications. As such, it has become an important design consideration in many situations. The materials investigated in the present studies are stainless steels, Ti-6Al-4V, alumina ceramics, with and without silicate glassy phase, and zirconia. These are some of the potential materials for use in the high temperature erosive-corrosive environments. The erosion or erosion-corrosion experiments were performed in a high temperature sand-blast type of test rig. The variables studied included the temperature, material composition, heat treatment condition, impingement velocity and angle, erodent concentration, etc. The morphological features of the eroded or eroded-corroded surfaces, substrate deformation, and oxide characteristics were studied by optical and scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, thermogravimetric analysis. The scratch test, single ball impact, and indentation tests were used to understand the behavior of oxide film in particle impacts. Based on these studies, the understanding of the mechanisms involved in the mechanical or combined mechanical and chemical actions in erosion was developed

Measurement of erosion: Is it possible?

NARCIS (Netherlands)

Stroosnijder, L.

2005-01-01

Reasons for erosion measurements are: (1) to determine the environmental impact of erosion and conservation practices, (2) scientific erosion research; (3) development and evaluation of erosion control technology; (4) development of erosion prediction technology and (5) allocation of conservation

Research for the development of the crushed sand (II)

Energy Technology Data Exchange (ETDEWEB)

Park, Chul Whan; Kang, Sun Duck; Min, Jeong Sik; Synn, Joong Ho; Park, Chan [Korea Institute of Geology Mining and Materials, Taejon (Korea)

1998-12-01

The sand obtained from river is not sufficient in amount for the demand of construction industry. The production of sand from sea and mountain is rapidly increasing for the substitution of the river sand. The industry of the crushed sand has recently been bricked for the above. Crushing, classification and dewatering are the main processes in the crushed sand production. This report concentrates the improvement of classification technology and the quality of ready mixed concrete. Air separator with testing size for the classification in the process of dry system was developed by the Yeung Nam university. This plant has the excellent efficiency for the collection of fine powder, but needs the improvement for separating function. The collection efficiency of the testing size air separator is reached to 99% in the condition of high revolution and low feeding speed. The classification efficiency is checked about 50% maximum in the condition of 200 rpm and dry sample. Energy saving test was carried out in the production process of the dry system with the rock samples of 14-17% of water content. The classification efficiency for dewatering sample passed the heating process was analysed 91.5%. But that for high water content sample skipped the heating process was analysed more or less 77%. Even though the heating process causes the classification efficiency being high, the energy consumption can also cause the price of the crushed sand high. Water content of sample as the effective element for the optimization of classification efficiency and energy saving should be studied next year. The quality of crushed sand in the mixing design. The test was carried out with the various content in mixing, the strength of ready mixed concrete has the maximum for the mould with 50-60% content of crushed sand. This strength is higher by 5-30% than 30% content and by 20-32% than 0% content, which means that the industry has the possibility of progress. (author). 10 refs., 31 tabs., 49

Susceptibility of coarse-textured soils to soil erosion by water in the tropics

International Nuclear Information System (INIS)

Salako, F.K.

2004-01-01

The application of soil physics for the evaluation of factors of soil erosion in the tropics received considerable attention in the last four decades. In Nigeria, physical characteristics of rainfall such as drop size and drop-size distribution, rainfall intensity at short intervals and kinetic energy of rainfall were evaluated using different methods. Thus, compound erosivity indices were evaluated which showed a similar trend in annual rainfall erosivity with annual rainfall amounts. Attempts have also been made to use geostatistical tools and fractal theory to describe temporal variability in rainfall erosivity. High erosivity aggravates the vulnerability of coarse-textured soils to erosion. These soils, high in sand content were poorly aggregated and structurally weak. Thus, they were easily detached and transported by runoff. Long-term data are needed to describe factors of soil erosion in the tropics but quite often, equipment are not available or poorly maintained where available such that useful data are not collected. A greater cooperation of pure physicists, soil physicists and engineers in the developing nations is needed to improve or design equipment and methods for the characterization of factors of soil erosion in the tropics. (author)

Soil physical properties affecting soil erosion in tropical soils

International Nuclear Information System (INIS)

Lobo Lujan, D.

2004-01-01

detachment. Studies on necessary kinetic energy to detach one kilogram of sediments by raindrop impact have shown that the minimum energy is required for particles of 0.125 mm. Particles between 0.063 to 0.250 mm are the most vulnerable to detachment. This means that soils with high content of particles into vulnerable range, for example silty loam, loamy, fine sandy, and sandy loam are the most susceptible soils to detachment. Many aspects of soil behaviour in the field such as hydraulic conductivity water retention, soil crusting, soil compaction, and workability are influenced strongly by the primary particles. In tropical soils also a negative relation between structure stability and particles of silt, fine sand and very fine sand has been found, this is attributed to low cohesiveness of these particles. The ability of a structure to persist is known as its stability. There are two principal types of stability: the ability of the soil to retain its structure under the action of water, and the ability of the soil to retain its structure under the action of external mechanical stresses. (e.g. by wheels). Both types of stability are related with susceptibility to erosion

Erosion and erosion-corrosion

International Nuclear Information System (INIS)

Isomoto, Yoshinori

2008-01-01

It is very difficult to interpret the technical term of erosion-corrosion' which is sometimes encountered in piping systems of power plants, because of complicated mechanisms and several confusing definitions of erosion-corrosion phenomena. 'FAC (flow accelerated corrosion)' is recently introduced as wall thinning of materials in power plant systems, as a representative of 'erosion-corrosion'. FAC is, however, not necessarily well understood and compared with erosion-corrosion. This paper describes firstly the origin, definition and fundamental understandings of erosion and erosion-corrosion, in order to reconsider and reconfirm the phenomena of erosion, erosion-corrosion and FAC. Next, typical mapping of erosion, corrosion, erosion-corrosion and FAC are introduced in flow velocity and environmental corrosiveness axes. The concept of damage rate in erosion-corrosion is finally discussed, connecting dissolution rate, mass transfer of metal ions in a metal oxide film and film growth. (author)

Is research on soil erosion hazard and mitigation in the Global South still needed? (Alexander von Humbold Medal Lecture)

Science.gov (United States)

Poesen, Jean

2016-04-01

Soil erosion represents a geomorphological and geological hazard that may cause environmental damage (land degradation), property damage, loss of livelihoods and services as well as social and economic disruption. Erosion not only lowers the quality of our soils on site, resulting in a drastic reduction of their ecosystem functions that play a vital role in daily life, but causes also significant sediment-related problems off site. To curb soil erosion problems, a range of soil conservation techniques and strategies have been designed and are being applied. Worldwide, ca. 62 000 research papers on soil erosion and 116 000 on soil conservation have been published (Web of Science, Dec. 2015). The number of such papers dealing with the Global South represents less than 20 % of all papers, despite the fact that many regions in this part of the world face significant soil erosion problems, aggravated by a rapidly growing population and major environmental changes. Given the large number of research papers on this topic, one might therefore conclude that we now know almost everything about the various soil erosion processes and rates, their factors and consequences as well as their control so that little new knowledge can still be added to the vast amount of available information. We refute this conclusion by pointing to some major research gaps that still need to be addressed if we want to use our soils in a more sustainable way. More specifically the following topics need more research attention: 1) improved understanding of both natural and anthropogenic soil erosion processes and their interactions, 2) scaling up soil erosion processes and rates in space and time, and 3) innovative techniques and strategies to prevent or reduce erosion rates. This will be illustrated with case studies from the Global South. If future research focuses on these research gaps, we will 1) better understand processes and their interactions operating at a range of spatial and temporal

A durability test rig and methodology for erosion-resistant blade coatings in turbomachinery

Science.gov (United States)

Leithead, Sean Gregory

A durability test rig for erosion-resistant gas turbine engine compressor blade coatings was designed, completed and commissioned. Bare and coated 17-4PH steel V103-profile blades were rotated at up to 11500 rpm and impacted with Garnet sand for 5 hours at an average concentration of 2.51 gm3of air , at a blade leading edge Mach number of 0.50. The rig was determined to be an acceptable first stage axial compressor representation. Two types of 16 microm-thick coatings were tested: Titanium Nitride (TiN) and Chromium-Aluminum-Titanium Nitride (CrAlTiN), both applied using an Arc Physical Vapour Deposition technique at the National Research Council in Ottawa, Canada. A Leithead-Allan-Zhao (LAZ) score was created to compare the durability performance of uncoated and coated blades based on mass-loss and blade dimension changes. The bare blades' LAZ score was set as a benchmark of 1.00. The TiN-coated and CrAlTiN-coated blades obtained LAZ scores of 0.69 and 0.41, respectively. A lower score meant a more erosion-resistant coating. Major modes of blade wear included: trailing edge, leading edge and the rear suction surface. Trailing edge thickness was reduced, the leading edge became blunt, and the rear suction surface was scrubbed by overtip and recirculation zone vortices. It was found that the erosion effects of vortex flow were significant. Erosion damage due to reflected particles was not present due to the low blade solidity of 0.7. The rig is best suited for studying the performance of erosion-resistant coatings after they are proven effective in ASTM standardized testing. Keywords: erosion, compressor, coatings, turbomachinery, erosion rate, blade, experimental, gas turbine engine

Sand transportation and reverse patterns over leeward face of sand dune

Science.gov (United States)

Jiang, Hong; Dun, Hongchao; Tong, Ding; Huang, Ning

2017-04-01

decreases with height in the reversed direction. The height of 0.5 H is the height of vortex core in the reversed flow region. The vortex core is a critical point in the flow region where few particles are transited. In the reversed region, the reversed mass flux of sand particles is 25% of the mass flux in the flow direction. This research may contribute to scientific understanding of the mechanisms of sand motion and wind flow over leeward of dune and it is likely to be significant in desertification control.

Liquefaction resistance of calcareous sands

International Nuclear Information System (INIS)

Sandoval Vallejo, Eimar

2012-01-01

Calcareous sands are unique in terms of their origin, mineralogy, shape, fragility and intra particle porosity. This article presents results from an experimental program carried out to study the liquefaction resistance of a calcareous sand retrieved from Cabo Rojo at Puerto Rico. The experimental program included mineralogical characterization, index properties, and undrained cyclic triaxial tests on isotropically consolidated reconstituted samples. Due to the large variation in the calcareous sand properties, results are compared with previous researches carried out on other calcareous sands around the world. Results showed a wide range in the liquefaction resistance of the studied calcareous sands. Cabo Rojo sand experienced greater liquefaction resistance than most of the calcareous sands used for comparison. Important differences in the excess pore pressure generation characteristics were also found.

Analyzing the Sand-fixing Effect of Feldspathic Sandstone from the Texture Characteristics

Science.gov (United States)

Zhang, lu; Ban, Jichang

2018-01-01

The purpose of this research was aimed to study the sand fixing effect of feldspathic sandstone in Mu Us Sandy Land, to provide a scienticic basis for desertification control, soil and water conservation and development of farming there. Methods of mixing feldspathic sandstone and aeolian sandy soil according to 1: 0, 1: 1, 1: 2, 1: 5, and 0: 1 mass ratioes, the graded composition and characteristics were studied with laser particle size analyzer. The result showed that these features of sand-based, loosely structured, easy to wind erosion of aeolian sandy soil were changed before feldspathic sandstone and aeolian sandy soil compounding. The <0.05 mm particle mass increased with feldspathic sandstone mass increasing. The texture presented this kind of change from sand to sandy loam to loam to silt loam. The small particle size distribution, good homogeneity and other features of aeolian sandy soil were improved to a certain degree, and the particle size distribution became broad before feldspathic sandstone and aeolian sandy soil compounding. The particle grading was continuous, and the grading characteristic was good when m(F): m(S) was 1: 5(Cu was 54.71 and Cc was 2.54) or when m(F): m(S) was 1: 2(Cu was 76.21, Cc was 1.12). The conclusion is that feldspathic sandstone has sand-fixing effect in texture characteristics, which heightens with feldspathic sandstone mass increasing, and when the mass ratio of feldspathic sandstone: aeolian sandy soil is 1: 2 or 1: 5 which compound better.

Sand-RAPG combination simulating fertile clayey soil (Part I to IV)

International Nuclear Information System (INIS)

Azzam, R.; El-Hady, O.A.; Lotfy, A.A.; Hegela, M.

1983-01-01

I. Radiation Preparation of RAPG. Sites of co-ordination and reinforcement are dominated in reclaimer ameliorator polymeric gel (RAPG). It is a modified acrylonitrile base multifunction polymer grafted upon a binder of worthless cellulosic agricultural discard. It varies chemically from non-ionic through anionic and cationic to ampholite. The hydroproperty of the gel is similarly controlled. Thus, RAPG can be tailored for any soil texture under various climatic conditions. II. Structure Stability and Maintenance. Sinai dune sand is treated with non-ionic and anionic RAPGs at rates varying from 0.05 to 0.2 wt.%. The stability increased with RAPG anionicity and application rate. The structure formed maintained three cycles of complete destruction and re-formation without significant changes in erosion index. The resistance of sand-RAPG combination to breakdown by tillage, as well as to wind and water erosion, is practically proved. This is in addition to the beneficial changes in bulk density, void ratio and microporosity, which were also achieved. III. Water Preservation. Inshas sandy soil treated by RAPG is compared with fertile clayey soil. The water-holding capacity and retention at different suctions are increased. The available water to plants in treated sand has reached 15 times that of the control, and even exceeded clay by 11%. Water losses by evaporation and leaching as well as deep percolation are all reduced to a minimum. IV. Plantation and Nutritional Status. Pepper seed germination, growth and dry matter are increased in the sand-RAPG combination relative to fertile clayey soil. The optimum rate and anionicity of RAPG are determined. This increases water-use efficiency to twice that of the fertile clayey soil. Macro- and micro-nutrient uptake have also increased. Thus, fertilizer use efficiency is increased by almost three times over that of clay. These factors lead convincingly to the conclusion that RAPG furnishes adequate conditions for sandy soil

In situ recovery of oil from Utah tar sand: a summary of tar sand research at the Laramie Energy Technology Center

Energy Technology Data Exchange (ETDEWEB)

Marchant, L.C.; Westhoff, J.D.

1985-10-01

This report describes work done by the United States Department of Energy's Laramie Energy Technology Center from 1971 through 1982 to develop technology for future recovery of oil from US tar sands. Work was concentrated on major US tar sand deposits that are found in Utah. Major objectives of the program were as follows: determine the feasibility of in situ recovery methods applied to tar sand deposits; and establish a system for classifying tar sand deposits relative to those characteristics that would affect the design and operation of various in situ recovery processes. Contents of this report include: (1) characterization of Utah tar sand; (2) laboratory extraction studies relative to Utah tar sand in situ methods; (3) geological site evaluation; (4) environmental assessments and water availability; (5) reverse combustion field experiment, TS-1C; (6) a reverse combustion followed by forward combustion field experiment, TS-2C; (7) tar sand permeability enhancement studies; (8) two-well steam injection experiment; (9) in situ steam-flood experiment, TS-1S; (10) design of a tar sand field experiment for air-stream co-injection, TS-4; (11) wastewater treatment and oil analyses; (12) economic evaluation of an in situ tar sand recovery process; and (13) appendix I (extraction studies involving Utah tar sands, surface methods). 70 figs., 68 tabs.

Provenance and recycling of Arabian desert sand

Science.gov (United States)

Garzanti, Eduardo; Vermeesch, Pieter; Andò, Sergio; Vezzoli, Giovanni; Valagussa, Manuel; Allen, Kate; Kadi, Khalid A.; Al-Juboury, Ali I. A.

2013-05-01

-Batin fossil alluvial fan or even from Mesozoic sandstones of the Arabian margin accreted to the Cenozoic Zagros orogen. Due to extensive recycling and the fact that zircon is so resistant to weathering and erosion, the U-Pb age signatures are much less powerful a tracer of sedimentary provenance than framework petrography and heavy minerals. Actualistic provenance studies of dune fields at subcontinental scale shed light on the generation and homogenization of aeolian sand, and allow us to trace complex pathways of multistep sediment transport, thus providing crucial independent information for accurate palaeogeographic and palaeoclimatic reconstructions.

Gully annealing by fluvially-sourced Aeolian sand: remote sensing investigations of connectivity along the Fluvial-Aeolian-hillslope continuum on the Colorado River

Science.gov (United States)

Sankey, Joel B.; East, Amy E.; Collins, Brian D.; Caster, Joshua J.

2015-01-01

Processes contributing to development of ephemeral gully channels are of great importance to landscapes worldwide, and particularly in dryland regions where soil loss and land degradation from gully erosion pose long-term, land-management problems. Whereas gully formation has been relatively well studied, much less is known of the processes that anneal gullies and impede their growth. This work investigates gully annealing by aeolian sediment, along the Colorado River downstream of Glen Canyon Dam in Glen, Marble, and Grand Canyons, Arizona, USA (Figure 1). In this segment of the Colorado River, gully erosion potentially affects the stability and preservation of archaeological sites that are located within valley margins. Gully erosion occurs as a function of ephemeral, rainfall-induced overland flow associated with intense episodes of seasonal precipitation. Measurements of sediment transport and topographic change have demonstrated that fluvial sand in some locations is transported inland and upslope by aeolian processes to areas affected by gully erosion, and aeolian sediment activity can be locally effective at counteracting gully erosion (Draut, 2012; Collins and others, 2009, 2012; Sankey and Draut, 2014). The degree to which specific locations are affected by upslope wind redistribution of sand from active channel sandbars to higher elevation valley margins is termed “connectivity”. Connectivity is controlled spatially throughout the river by (1) the presence of upwind sources of fluvial sand within the contemporary active river channel (e.g., sandbars), and (2) bio-physical barriers that include vegetation and topography that might impede aeolian sediment transport. The primary hypothesis of this work is that high degrees of connectivity lead to less gullying potential.

Plasma nitriding of a precipitation hardening stainless steel to improve erosion and corrosion resistance

International Nuclear Information System (INIS)

Cabo, Amado; Bruhl, Sonia P.; Vaca, Laura S.; Charadia, Raul Charadia

2010-01-01

Precipitation hardening stainless steels are used as structural materials in the aircraft and the chemical industry because of their good combination of mechanical and corrosion properties. The aim of this work is to analyze the structural changes produced by plasma nitriding in the near surface of Thyroplast PH X Supra®, a PH stainless steel from ThyssenKrupp, and to study the effect of nitriding parameters in wear and corrosion resistance. Samples were first aged and then nitriding was carried out in an industrial facility at two temperatures, with two different nitrogen partial pressures in the gas mixture. After nitriding, samples were cut, polished, mounted in resin and etched with Vilella reagent to reveal the nitrided case. Nitrided structure was also analyzed with XRD. Erosion/Corrosion was tested against sea water and sand flux, and corrosion in a salt spray fog (ASTM B117). All nitrided samples presented high hardness. Samples nitrided at 390 deg C with different nitrogen partial pressure showed similar erosion resistance against water and sand flux. The erosion resistance of the nitrided samples at 500 deg C was the highest and XRD revealed nitrides. Corrosion resistance, on the contrary, was diminished; the samples suffered of general corrosion during the salt spray fog test. (author)

bentonite-sand mixture as new backfill/buffer material

International Nuclear Information System (INIS)

Cui Suli; Liu Jisheng; Zhang Huyuan; Liang Jian

2008-01-01

The mixture of bentonite and quartz sand is suggested as a new backfill/buffer material for geological disposal of HLW. To improve the further design of underground laboratory and in-situ industrial construction test, the optimization of sand addition to bentonite is focused at present research stage. Based on summarizing the research results abroad, laboratory tests were conducted on the mixture of GMZ001 bentonite and quartz sand, such as compaction test and swelling tests etc. Test data shows that GMZ bentonite-sand mixture exhibits a favorite compaction with a 30% sand addition, a highest swelling pressure with a 20% sand addition, and a decreasing plasticity with increases in sand addition and pore liquid concentration. (authors)

Design and Performance Optimizations of Advanced Erosion-Resistant Low Conductivity Thermal Barrier Coatings for Rotorcraft Engines

Science.gov (United States)

Zhu, Dongming; Miller, Robert A.; Kuczmarski, Maria A.

2012-01-01

Thermal barrier coatings will be more aggressively designed to protect gas turbine engine hot-section components in order to meet future rotorcraft engine higher fuel efficiency and lower emission goals. For thermal barrier coatings designed for rotorcraft turbine airfoil applications, further improved erosion and impact resistance are crucial for engine performance and durability, because the rotorcraft are often operated in the most severe sand erosive environments. Advanced low thermal conductivity and erosion-resistant thermal barrier coatings are being developed, with the current emphasis being placed on thermal barrier coating toughness improvements using multicomponent alloying and processing optimization approaches. The performance of the advanced thermal barrier coatings has been evaluated in a high temperature erosion burner rig and a laser heat-flux rig to simulate engine erosion and thermal gradient environments. The results have shown that the coating composition and architecture optimizations can effectively improve the erosion and impact resistance of the coating systems, while maintaining low thermal conductivity and cyclic oxidation durability

Preliminary evaluation of the physical impacts of a nearshore sand extraction project

International Nuclear Information System (INIS)

Anctil, F.; Ouellet, Y.

1991-01-01

A review is presented of the potential physical impacts of a nearshore sand extraction project in the Gulf of St. Lawrence. In Canada, sand extraction is mainly limited to the Beaufort Sea area, where in 1982 alone 15 million tonnes of aggregate was dredged to satisfy the requirements of offshore petroleum exploration; but there is much experience in nearshore dredging in Europe. Criteria related to impacts, developed for conditions prevailing in the North Sea (England) and the Gulf of Gascogne (France) are adapted to meet the more moderate hydrodynamic impacts of an extraction project in the Gulf of St. Lawrence. Potential impacts of extraction projects include destruction of sand bars or dunes, direct erosion resulting from beach drawdown or sedimentation interference, and impacts on littoral drift due to modified wave refraction patterns. Three schemes for the sand extraction are considered, and from the results, a fourth scheme is elaborated in such a way as to limit the negative impacts to the minor category. 17 refs., 5 figs., 4 tabs

Documenting the global impacts of beach sand mining

Science.gov (United States)

Young, R.; Griffith, A.

2009-04-01

For centuries, beach sand has been mined for use as aggregate in concrete, for heavy minerals, and for construction fill. The global extent and impact of this phenomenon has gone relatively unnoticed by academics, NGOs, and major news sources. Most reports of sand mining activities are found at the very local scale (if the mining is ever documented at all). Yet, sand mining in many localities has resulted in the complete destruction of beach (and related) ecosystems along with severe impacts to coastal protection and tourism. The Program for the Study of Developed Shorelines at Western Carolina University and Beachcare.org have initiated the construction of a global database of beach sand mining activities. The database is being built through a combination of site visits and through the data mining of media resources, peer reviewed papers, and reports from private and governmental entities. Currently, we have documented sand mining in 35 countries on 6 continents representing the removal of millions of cubic meters of sand. Problems extend from Asia where critical infrastructure has been disrupted by sand mining to the Caribbean where policy reform has swiftly followed a highly publicized theft of sand. The Program for the Study of Developed Shorelines recently observed extensive sand mining in Morocco at the regional scale. Tens of kilometers of beach have been stripped of sand and the mining continues southward reducing hope of a thriving tourism-based economy. Problems caused by beach sand mining include: destruction of natural beaches and the ecosystems they protect (e.g. dunes, wetlands), habitat loss for globally important species (e.g. turtles, shorebirds), destruction of nearshore marine ecosystems, increased shoreline erosion rates, reduced protection from storms, tsunamis, and wave events, and economic losses through tourist abandonment and loss of coastal aesthetics. The threats posed by sand mining are made even more critical given the prospect of a

Vegetation morphologic and aerodynamic characteristics reduce aeolian erosion.

Science.gov (United States)

Miri, Abbas; Dragovich, Deirdre; Dong, Zhibao

2017-10-09

Vegetation cover is crucial to controlling aeolian erosion but highly efficient vegetation is critical. How this efficiency is influenced by vegetation response to airflow is not clear. Here we evaluate the responses of Cosmos bipinnatus and Ligustrum lucidum Ait to a range of wind speeds in a wind tunnel. For both species, we calculate shelter effect and sand flux. We show that plant effectiveness in reducing wind speed and sediment transport is linked to their aerodynamic response to airflow which results from their morphology. We demonstrate that in low-density cover the flow-response and resistance of individuals is most critical in the optimal effectiveness of a canopy. Our wind tunnel experiment suggests that vegetation morphology and structure must be priority parameters in facilitating aeolian erosion control.

Challenges in soil erosion research and prediction model development

Science.gov (United States)

Quantification of soil erosion has been traditionally considered as a surface hydrologic process with equations for soil detachment and sediment transport derived from the mechanics and hydraulics of the rainfall and surface flow. Under the current erosion modeling framework, the soil has a constant...

Influence green sand system by core sand additions

Directory of Open Access Journals (Sweden)

N. Špirutová

2012-01-01

Full Text Available Today, about two thirds of iron alloys casting (especially for graphitizing alloys of iron are produced into green sand systems with usually organically bonded cores. Separation of core sands from the green sand mixture is very difficult, after pouring. The core sand concentration increase due to circulation of green sand mixture in a closed circulation system. Furthermore in some foundries, core sands have been adding to green sand systems as a replacement for new sands. The goal of this contribution is: “How the green sand systems are influenced by core sands?”This effect is considered by determination of selected technological properties and degree of green sand system re-bonding. From the studies, which have been published yet, there is not consistent opinion on influence of core sand dilution on green sand system properties. In order to simulation of the effect of core sands on the technological properties of green sands, there were applied the most common used technologies of cores production, which are based on bonding with phenolic resin. Core sand concentration added to green sand system, was up to 50 %. Influence of core sand dilution on basic properties of green sand systems was determined by evaluation of basic industrial properties: moisture, green compression strength and splitting strength, wet tensile strength, mixture stability against staling and physical-chemistry properties (pH, conductivity, and loss of ignition. Ratio of active betonite by Methylene blue test was also determined.

Management of Coastal Erosion Using Remote Sensing and GIS Techniques (SE India

Directory of Open Access Journals (Sweden)

S. Saravanan

2014-12-01

Full Text Available World wide, coastal erosion is recognized as a great threat for beach environment. Total control of coastal erosion is not feasible but it should not be ignored and needs timely management. Erosional activities have been significantly noticed along the coastal tract of Vembar and Kallar (Kallurani, South India. An attempt has been made here to delineate different zones based on their sand budget and erosion rate. Linear Imaging Self Scanning Sensor (LISS III 2001 and Linear Imaging Self Scanning Sensor III and PAN merged data of the year 2001 have been utilized to identify the coastal geomorphological features, shoreline changes and river course changes. A Geographic Information System (GIS software namely ArcGIS (9.1 has been used as a tool to delineate the coastal erosion hazard for proper planning and management of coastal developments. Beach profile studies have shown significant variation in the beach morphology. The study area has been categorized into five different zones in the GIS analysis based on the degree of coastal erosion and sediment dynamics namely (i very high - Kalaignanapuram, (ii high - Sippikulam (iii medium - Periyasamypuram (iv low - Vembar and Kallar (Kallurani (v very low - Pachayapuram.

Aeolian sands and buried soils in the Mecklenburg Lake District, NE Germany: Holocene land-use history and pedo-geomorphic response

Science.gov (United States)

Küster, Mathias; Fülling, Alexander; Kaiser, Knut; Ulrich, Jens

2014-04-01

The present study is a pedo-geomorphic approach to reconstructing Holocene aeolian sand dynamics in the Mecklenburg Lake District (NE Germany). Stratigraphical, sedimentological and soil research supplemented by morphogenetic interpretations of the genesis of dunes and aeolian sands are discussed. A complex Late Holocene aeolian stratigraphy within a drift sand area was developed at the shore of Lake Müritz. The results were confirmed using palynological records, archaeological data and regional history. Accelerated aeolian activity was triggered by the intensification of settlement and land-use activities during the 13th and in the 15th to 16th century AD. After a period of stability beginning with population decline during the ‘Thirty Years War' and continuing through the 18th century, a final aeolian phase due to the establishment of glassworks was identified during the 19th century AD. We assume a direct link between Holocene aeolian dynamics and human activities. Prehistoric Holocene drift sands on terrestrial sites have not been documented in the Mecklenburg Lake District so far. This might be explained either by erosion and incorporation of older aeolian sediments during younger aeolian phases and/or a lower regional land-use intensity in older periods of the Holocene. The investigated drift sands are stratigraphically and sedimentologically characterised by a high degree of heterogeneity, reflecting the spatial and temporal variability of Holocene human impact.

A bright intra-dune feature on Titan and its implications for sand formation and transport

Science.gov (United States)

MacKenzie, Shannon; Barnes, Jason W.; Rodriguez, Sebastien; Cornet, Thomas; Brossier, Jeremy; Soderblom, Jason M.; Le Mouélic, Stephane; Sotin, Christophe; Brown, Robert H.; Buratti, Bonnie J.; Clark, Roger Nelson; Nicholson, Philip D.; Baines, Kevin

2017-10-01

Organic sands cover much of Titan’s equatorial belt, gathered into longitudinal dunes about a kilometer wide and hundreds of kilometers long. At the end of the Cassini era, questions of how such a vast volume of saltable material is or was created on Titan remain unanswered. At least two possible mechanisms suggested for forming sand-sized particles involve liquids: (1) evaporite deposition and erosion and (2) flocculation of material within a lake. Transporting sand from the lakes and seas of Titan’s poles to the equatorial belt is not strongly supported by Cassini observations: the equatorial belt sits higher than the poles and no sheets or corridors of travelling sand have been identified. Thus, previous sites of equatorial surface liquids may be of interest for understanding sand formation, such as the suggested paleoseas Tui and Hotei Regio. A newly identified feature in the VIMS data sits within the Fensal dune field but is distinct from the surrounding sand. We investigate this Bright Fensal Feature (BFF) using data from Cassini VIMS and RADAR. Specifically, we find spectral similarities between the BFF and both sand and Hotei Regio. The RADAR cross sectional backscatter is similar to neighboring dark areas, perhaps sand covered interdunes. We use this evidence to constrain the BFF’s formation history and discuss how this intra-dune feature may contribute to the processes of sand transport and supply.

Erosion patterns produced by the paleo Haizishan ice cap, SE Tibetan Plateau

Science.gov (United States)

Fu, P.; Stroeven, A. P.; Harbor, J.; Hättestrand, C.; Heyman, J.; Caffee, M. W.

2017-12-01

Erosion is a primary driver of landscape evolution, topographic relief production, geochemical cycles, and climate change. Combining in situ 10Be and 26Al exposure age dating, geomorphological mapping, and field investigations, we examine glacial erosion patterns of the almost 4,000 km2 paleo Haizishan ice cap on the southeastern Tibetan Plateau. Our results show that ice caps on the low relief Haizishan Plateau produced a zonal pattern of landscape modification. In locations where apparent exposure ages on bedrock are consistent with the last deglaciation, complete resetting of the cosmogenic exposure age clock indicates glacial erosion of at least a few meters. However, older apparent exposure ages on bedrock in areas known to have been covered by the paleo ice cap during the Last Glacial Maximum indicate inheritance and thus limited glacial erosion. Inferred surface exposure ages from cosmogenic depth profiles through two saprolites vary from resetting and thus saprolite profile truncation to nuclide inheritance indicating limited erosion. Finally, significant nuclide inheritance in river sand samples from basins on the scoured plateau surface also indicate limited glacial erosion during the last glaciation. Hence, for the first time, our study shows clear evidence of preservation under non-erosive ice on the Tibetan Plateau. As patterns of glacial erosion intensity are largely driven by the basal thermal regime, our results confirm earlier inferences from geomorphology for a concentric basal thermal pattern for the paleo Haizishan ice cap during the LGM.

Preliminary assessments of the occurrence and effects of utilization of sand and aggregate resources of the Louisiana inner shelf

Science.gov (United States)

Suter, J.R.; Mossa, J.; Penland, S.

1989-01-01

Louisiana is experiencing the most critical coastal erosion and land loss problem in the United States. Shoreline erosion rates exceed 6 m/yr in more than 80% of the Louisiana coastal zone and can be up to 50 m/yr in areas impacted by hurricanes. The barrier islands have decreased in area by some 40% since 1880. Land loss from coastal marshlands and ridgelands from both natural and human-induced processes is estimated to exceed 100 km2/yr. In response, a two-phase plan has been established, calling for barrier-island restoration and beach nourishment, both requiring large amounts of sand. The plan will be cost-effective only if sand can be found offshore in sufficient quantities close to project sites. To locate such deposits, the Louisiana Geological Survey is conducting an inventory of nearshore sand resources on the Louisiana continental shelf. Exploration for offshore sand deposits is conducted in two phases, with high-resolution seismic reflection profiling to locate potential sand bodies followed by vibracoring to confirm seismic intepretations and obtain samples for textural characterization. As part of the initial stages of the program, reconnaissance high-resolution seismic investigations of three areas of the continental shelf representing different stages in the evolutionary sequence of barrier shorelines were carried out. The Timbalier Islands, flanking barriers of the eroding Caminada-Moreau headland, contain potential sand resources associated with buried tidal and distributary channels. The Chandeleur Islands, a barrier-island arc, have potential offshore sands in the form of truncated spit and tidal inlet deposits, submerged beach ridges, and distributary channels. Trinity Shoal, an inner shelf shoal, is an offshore feature containing up to 2 ?? 109 m3 of material, most of which is probably fine sand. These reconnaissance surveys have demonstrated the occurrence of sand resources on the Louisiana continental shelf. Utilization of such deposits for

Growth, Failure, and Erosion of Submarine Channel Levees on the Upper Mississippi Fan, Gulf of Mexico

Science.gov (United States)

Sawyer, D. E.; Flemings, P. B.; Nikolinakou, M. A.

2011-12-01

Late Pleistocene channel levees on the Mississippi Fan failed repeatedly along deep-seated listric faults. These growth faults begin at the top of the levee, as much as a kilometer away from the channel axis. They plunge 150-200 meters downward reaching their deepest point halfway towards the channel axis (0.5 km) along the base of a regional sand unit. They then rise toward the channel axis where they emerge. The erosion of toe-thrust material coupled with levee growth, promoted a dynamic equilibrium: turbidity currents flushed the channel axis and deposited new levee on the margins, which induced further displacement into the channel. With a geomechanical model we show that deep-seated failure occurred by undrained loading of an underlying low permeability mudstone. Excess pore pressure formed a low-strength layer that localized the detachment at the base of a regional sand. Our results show that deep-seated failure is expected when levee systems form above regional sand bodies that were deposited rapidly above low permeability mudstone. Furthermore, the presence of this failure style in channel-levee systems is a strong indicator that overpressures and low effective stresses were present during formation and thus record paleo-pressures. Understanding these systems is critical for the design of safe well penetrations, predicting hydraulic connectivity of deepwater channel sands, and the growth of submarine channel-levee systems. This study illuminates the linkages between sedimentation, erosion, and the mechanical stability of levees in submarine channel systems.

Erosion potential from Missoula floods in the Pasco Basin, Washington

International Nuclear Information System (INIS)

Craig, R.G.; Hanson, J.P.

1985-12-01

Localities within the Pasco Basin preserve evidence of Missoula floods. Deposits are 46% sand-sized, 36% gravel-sized, and 18% finer than sand-sized. Mean thickness is 39 meters. High water marks at Wallula Gap require a discharge of approximately 12.5 Mcms. At Sentinel Gap, the slope-area method shows that the high water marks require a discharge of 34.6 Mcms. Since this discharge greatly exceeds any estimated for Missoula floods, there must have been backwater ponding from Wallula Gap. Projecting the slope of the water surface at the upper end of Wallula Gap to the downstream cross section at Gable Mountain leads to a discharge of 9.5 Mcms at Sentinel Gap. The HEC-6 steady state code and four sediment transport equations were applied. Assuming sand-sized particles, DuBoys function estimated 4 to 9 meters of scour. Yang's equation estimated 3 to 4 meters of scour. These are a minimum. A hydrograph synthesized for the boundaries of the Pasco Basin shows the maxima of the flood would occur after 90 h at Sentinel Gap, and at 114 h at Wallula Gap. The 200 areas will remain inundated for four days and six hours. With a quasi-dynamic sediment transport computation, HEC-6 scour estimates range from 0.61 meters to 0.915 meters. This is a minimum amount and erosion is highly variable suggesting reworking of sediment. The Meyer-Peter Meuller equations show less than 1 meter of net scour in the 200 areas. More extensive erosion was achieved during particular time steps of this analysis suggesting that sediment re-working would occur

Erosion potential from Missoula floods in the Pasco Basin, Washington

Energy Technology Data Exchange (ETDEWEB)

Craig, R.G.; Hanson, J.P.

1985-12-01

Localities within the Pasco Basin preserve evidence of Missoula floods. Deposits are 46% sand-sized, 36% gravel-sized, and 18% finer than sand-sized. Mean thickness is 39 meters. High water marks at Wallula Gap require a discharge of approximately 12.5 Mcms. At Sentinel Gap, the slope-area method shows that the high water marks require a discharge of 34.6 Mcms. Since this discharge greatly exceeds any estimated for Missoula floods, there must have been backwater ponding from Wallula Gap. Projecting the slope of the water surface at the upper end of Wallula Gap to the downstream cross section at Gable Mountain leads to a discharge of 9.5 Mcms at Sentinel Gap. The HEC-6 steady state code and four sediment transport equations were applied. Assuming sand-sized particles, DuBoys function estimated 4 to 9 meters of scour. Yang's equation estimated 3 to 4 meters of scour. These are a minimum. A hydrograph synthesized for the boundaries of the Pasco Basin shows the maxima of the flood would occur after 90 h at Sentinel Gap, and at 114 h at Wallula Gap. The 200 areas will remain inundated for four days and six hours. With a quasi-dynamic sediment transport computation, HEC-6 scour estimates range from 0.61 meters to 0.915 meters. This is a minimum amount and erosion is highly variable suggesting reworking of sediment. The Meyer-Peter Meuller equations show less than 1 meter of net scour in the 200 areas. More extensive erosion was achieved during particular time steps of this analysis suggesting that sediment re-working would occur.

A Preliminary Experimental Investigation of Wet Fine Erosion in Two-Phase Flow

Science.gov (United States)

Ya, H. H.; Luthfi, Haziq; Ngo, Nguyet-Tran; Hassan, Suhaimi; Pao, William

2018-03-01

Solid particles below 62 μm is classified as fine. In oil producing operation, the most commonly used downhole sand screen can only capture solid particles of 140 μm and above. Most predictive erosion model is limited to particle size of 100 μm with single phase flow assumption because it is commonly believed that erosion due to particles below 100 μm is insignificant and typically ignored by oil and gas consultants when proposing facilities design. The objective of this paper is to investigate the impact of fines particle on mild steel plate in two-phase flow at different collision angles. A two phase flow loop was set up. The average size of fine particle was 60 μm, mixed with water with sand to water ratio at 1:65 wt/wt. The mild steel plates were oriented at three different impact angles which are -30°, 30° and 90°, with respect to the horizon. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), surface roughness and Vickers micro hardness techniques were used to quantify the effects of fine particle on the exposed surface.

Integrated spatial assessment of wind erosion risk in Hungary

Directory of Open Access Journals (Sweden)

L. Pásztor

2016-11-01

Full Text Available Wind erosion susceptibility of Hungarian soils was mapped on the national level integrating three factors of the complex phenomenon of deflation (physical soil features, wind characteristics, and land use and land cover. Results of wind tunnel experiments on erodibility of representative soil samples were used for the parametrization of a countrywide map of soil texture compiled for the upper 5 cm layer of soil, which resulted in a map representing threshold wind velocity exceedance. Average wind velocity was spatially estimated with 0.5′ resolution using the Meteorological Interpolation based on Surface Homogenised Data Basis (MISH method elaborated for the spatial interpolation of surface meteorological elements. The probability of threshold wind velocity exceedance was determined based on values predicted by the soil texture map at the grid locations. Ratio values were further interpolated to a finer 1 ha resolution using sand and silt content of the uppermost (0–5 cm layer of soil as spatial co-variables. Land cover was also taken into account, excluding areas that are not relevant to wind erosion (forests, water bodies, settlements, etc., to spatially assess the risk of wind erosion. According to the resulting map of wind erosion susceptibility, about 10 % of the total area of Hungary can be identified as susceptible to wind erosion. The map gives more detailed insight into the spatial distribution of wind-affected areas in Hungary compared to previous studies.

Effects of sand fences on coastal dune vegetation distribution

Science.gov (United States)

Grafals-Soto, Rosana

2012-04-01

Sand fences are important human adjustments modifying the morphology of developed shores. The effects of sand fences on sediment transport and deposition in their initial stages have been well studied, but little is known about the effect of deteriorated sand fences that have become partially buried low scale barriers within the dune, potentially benefiting vegetation growth by protecting it from onshore stress. Data on vegetation, topography and fence characteristics were gathered at three dune sites in Ocean City, New Jersey on September 2007 and March 2008 to evaluate the effect of fences within the dune on vegetation distribution. Variables include: distance landward of dune toe, degree of sheltering from onshore stressors, net change in surface elevation (deposition or erosion), vegetation diversity and density, presence of remnant fence, and distance landward of fence. Results for the studied environment reveal that 1) vegetation diversity or density does not increase near remnant fences because most remnants are lower than average vegetation height and can not provide shelter; but 2) vegetation distribution is related to topographic variables, such as degree of sheltering, that are most likely the result of sand accretion caused by fence deployment. Fence deployment that prioritizes the creation of topographically diverse dunes within a restricted space may increase the diversity and density of the vegetation, and the resilience and value of developed dunes. Managers should consider the benefits of using sand fences on appropriately wide beaches to create a protective dune that is also diverse, functional and better able to adapt to change.

Role of grounded ship 'MV River Princess' in triggering erosion: A case study from Candolim Sinquerim Coast, Goa.

Digital Repository Service at National Institute of Oceanography (India)

ManiMurali, R.; Babu, M.T.; Sudhesh, K.; Mascarenhas, A.; Vethamony, P.

are conducive for sand bar formation on the lee side. The intensity of winds and higher significant wave height (Hs) during SW monsoon further deteriorates the shore front which has already become fragile due to severe erosion along beach front...

Reclamation research for the future at Syncrude Canada Ltd. : soil simulation-revegetation studies on tailings sand

Energy Technology Data Exchange (ETDEWEB)

Fedkenheuer, A W; Browne, J

1979-12-01

In response to the rising demand for energy in today's world, oil extracted from oil sands has become a viable energy source. Syncrude Canada Ltd. is a 2.2 billion dollar oil sands surface mining and processing venture situated in the Athabasca oil sands of northeastern Alberta. It is located near the town of Fort McMurray approximately 420 km north of Edmonton. During its planned 25 years of mine life, Syncrude expects to produce more than 1 billion barrels of oil from a 2800 ha mine area. Syncrude is committed to reclaiming this immense mine area. The reclamation objective is to return the disturbed site to a vegetative cover having a productivity which is equal to or greater than that which existed prior to disturbance. The reclaimed area must also be compatible with the neighboring natural areas. To accomplish this the vast quantities of tailings sand (that is, the leftover sand from which the oil has been extracted) must be reformed into a soil which is capable of supporting native plant communities. Researchers at Syncrude are looking for ways to use indigenous materials with the tailings sand to simulate a naturally-formed soil. Native plant species are being tested to see how well they will grow in such simulated soils and to evaluate their potential for use in large scale reclamation projects. This brochure describes the soil simulation-revegetation experiments going on at Syncrude.

Pelton turbine Needle erosion prediction based on 3D three- phase flow simulation

International Nuclear Information System (INIS)

Chongji, Z; Yexiang, X; Wei, Z; Yangyang, Y; Lei, C; Zhengwei, W

2014-01-01

Pelton turbine, which applied to the high water head and small flow rate, is widely used in the mountainous area. During the operation period the sediment contained in the water does not only induce the abrasion of the buckets, but also leads to the erosion at the nozzle which may damage the needle structure. The nozzle and needle structure are mainly used to form high quality cylindrical jet and increase the efficiency of energy exchange in the runner to the most. Thus the needle erosion will lead to the deformation of jet, and then may cause the efficiency loss and cavitation. The favourable prediction of abrasion characteristic of needle can effectively guide the optimization design and maintenance of needle structure. This paper simulated the unsteady three-dimensional multi-phase flow in the nozzle and injected jet flow. As the jet containing water and sediment is injected into the free atmosphere air with high velocity, the VOF model was adopted to predict the water and air flow. The sediment is simplified into round solid particle and the discrete particle model (DPM) was employed to predict the needle abrasion characteristic. The sand particle tracks were analyzed to interpret the mechanism of sand erosion on the needle surface. And the numerical result of needle abrasion was obtained and compared with the abrasion field observation. The similarity of abrasion pattern between the numerical results and field observation illustrated the validity of the 3D multi-phase flow simulation method

Pelton turbine Needle erosion prediction based on 3D three- phase flow simulation

Science.gov (United States)

Chongji, Z.; Yexiang, X.; Wei, Z.; Yangyang, Y.; Lei, C.; Zhengwei, W.

2014-03-01

Pelton turbine, which applied to the high water head and small flow rate, is widely used in the mountainous area. During the operation period the sediment contained in the water does not only induce the abrasion of the buckets, but also leads to the erosion at the nozzle which may damage the needle structure. The nozzle and needle structure are mainly used to form high quality cylindrical jet and increase the efficiency of energy exchange in the runner to the most. Thus the needle erosion will lead to the deformation of jet, and then may cause the efficiency loss and cavitation. The favourable prediction of abrasion characteristic of needle can effectively guide the optimization design and maintenance of needle structure. This paper simulated the unsteady three-dimensional multi-phase flow in the nozzle and injected jet flow. As the jet containing water and sediment is injected into the free atmosphere air with high velocity, the VOF model was adopted to predict the water and air flow. The sediment is simplified into round solid particle and the discrete particle model (DPM) was employed to predict the needle abrasion characteristic. The sand particle tracks were analyzed to interpret the mechanism of sand erosion on the needle surface. And the numerical result of needle abrasion was obtained and compared with the abrasion field observation. The similarity of abrasion pattern between the numerical results and field observation illustrated the validity of the 3D multi-phase flow simulation method.

Sulphur extended oil sand mix : paving material for lower transport cost and CO{sub 2} reduction : ASRL Syncrude research project 1995

Energy Technology Data Exchange (ETDEWEB)

Aquin d' , G. [Con-Sul Inc., Missoula, MT (United States)

2010-07-01

This power point presentation discussed the use of sulphur-enhanced oil sands (SEOS) as a paving mixture. Sulphur has been added to asphaltic bitumen paving processes since the 1850s. Research into sulphur additions has been conducted by various Canadian industry members and institutions. A study in 1995 investigated the use of SEOS as a temporary paving material. The benefits of using SEOS included lower capital costs and lower greenhouse gas (GHG) impacts. Increases in equipment efficiency were also observed. Researchers are now developing mixing protocols and testing various paving materials in relation to temperature regimes and percentages of sulphur. Sand, limestone, coke, and rubber additions are also being evaluated, as well as the behaviour of SEOS in freeze-thaw cycles. To date, the studies have indicated that a 30 percent sulphur, 10 percent sand, and 60 percent oil sand mixture provides optimal compression and behaviour under freeze-thaw conditions. The use of SEOS paving at oil sands mine sites will reduce truck and road maintenance as well as reduce fuel emissions and consumption rates. tabs., figs.

Loadings of polynuclear aromatic compounds and metals to the Athabasca River watershed by oil sands mining and processing

International Nuclear Information System (INIS)

Hodson, P.V.

2010-01-01

The contribution of oil sands operations to pollution in the Athabasca River has not yet been determined. Wastes from oil sands processes include recycled water, sand, silt, clay, bitumen, and polycyclic aromatic compounds (PAC) and metals. Upgrading processes can also release significant quantities of PAC and heavy metals. This paper discussed a study in which PAC and metals in the snow pack and river water of the Athabasca watershed were assessed. The study showed that the oil sands industry is a significant source of contamination. The equivalent of 600 T of bitumen was observed at sites within 50 km of oil sands upgrading facilities. The strongest contamination signals occurred during the summer months, which suggested that the surface run-off of contaminated water was related to recent oil sands developments. Samples taken from tributaries in watersheds with little or no development indicated that increased concentrations of oil sands related contaminants were not caused by natural erosion. The contaminants may contribute to higher levels of mercury (Hg) and cadmium (Cd) in the flesh of fish and wildlife and increase toxicity to the embryos of spring-spawning fish.

Bituminous sands : tax issues

International Nuclear Information System (INIS)

Patel, B.

2004-01-01

This paper examined some of the tax issues associated with the production of bitumen or synthetic crude oil from oil sands. The oil sands deposits in Alberta are gaining more attention as the supplies of conventional oil in Canada decline. The oil sands reserves located in the Athabasca, Cold Lake and Peace River areas contain about 2.5 trillion barrels of highly viscous hydrocarbons called bitumen, of which nearly 315 billion barrels are recoverable with current technology. The extraction method varies for each geographic area, and even within zones and reservoirs. The two most common extraction methods are surface mining and in-situ extraction such as cyclic steam stimulation (CSS); low pressure steam flood; pressure cycle steam drive; steam assisted gravity drainage (SAGD); hot water flooding; and, fire flood. This paper also discussed the following general tax issues: bituminous sands definition; bituminous sands leases and Canadian development expense versus Canadian oil and gas property expense (COGPE); Canadian exploration expense (CEE) for surface mining versus in-situ methods; additional capital cost allowance; and, scientific research and experimental development (SR and ED). 15 refs

Augmenting Sand Simulation Environments through Subdivision and Particle Refinement

Science.gov (United States)

Clothier, M.; Bailey, M.

2012-12-01

Recent advances in computer graphics and parallel processing hardware have provided disciplines with new methods to evaluate and visualize data. These advances have proven useful for earth and planetary scientists as many researchers are using this hardware to process large amounts of data for analysis. As such, this has provided opportunities for collaboration between computer graphics and the earth sciences. Through collaboration with the Oregon Space Grant and IGERT Ecosystem Informatics programs, we are investigating techniques for simulating the behavior of sand. We are also collaborating with the Jet Propulsion Laboratory's (JPL) DARTS Lab to exchange ideas and gain feedback on our research. The DARTS Lab specializes in simulation of planetary vehicles, such as the Mars rovers. Their simulations utilize a virtual "sand box" to test how a planetary vehicle responds to different environments. Our research builds upon this idea to create a sand simulation framework so that planetary environments, such as the harsh, sandy regions on Mars, are more fully realized. More specifically, we are focusing our research on the interaction between a planetary vehicle, such as a rover, and the sand beneath it, providing further insight into its performance. Unfortunately, this can be a computationally complex problem, especially if trying to represent the enormous quantities of sand particles interacting with each other. However, through the use of high-performance computing, we have developed a technique to subdivide areas of actively participating sand regions across a large landscape. Similar to a Level of Detail (LOD) technique, we only subdivide regions of a landscape where sand particles are actively participating with another object. While the sand is within this subdivision window and moves closer to the surface of the interacting object, the sand region subdivides into smaller regions until individual sand particles are left at the surface. As an example, let's say

Deposition behaviour of model biofuel ash in mixtures with quartz sand. Part 1: Experimental data

Energy Technology Data Exchange (ETDEWEB)

Mischa Theis; Christian Mueller; Bengt-Johan Skrifvars; Mikko Hupa; Honghi Tran [Aabo Akademi Process Chemistry Centre, Aabo (Finland). Combustion and Materials Chemistry

2006-10-15

Model biofuel ash of well-defined size and melting properties was fed into an entrained flow reactor (EFR) to simulate the deposition behaviour of commercially applied biofuel mixtures in large-scale boilers. The aim was to obtain consistent experimental data that can be used for validation of computational fluid dynamics (CFD)-based deposition models. The results showed that while up to 80 wt% of the feed was lost to the EFR wall, the composition of the model ash particles collected at the reactor exit did not change. When model ashes were fed into the reactor individually, the ash particles were found to be sticky when they contained more than 15 wt% molten phase. When model ashes were fed in mixtures with silica sand, it was found that only a small amount of sand particles was captured in the deposits; the majority rebounded upon impact. The presence of sand in the feed mixture reduced the deposit buildup by more than could be expected from linear interpolation between the model ash and the sand. The results suggested that sand addition to model ash may prevent deposit buildup through erosion. 22 refs., 6 figs., 3 tabs.

Wind Erosion Induced Soil Degradation in Northern China: Status, Measures and Perspective

Directory of Open Access Journals (Sweden)

Zhongling Guo

2014-12-01

Full Text Available Soil degradation is one of the most serious ecological problems in the world. In arid and semi-arid northern China, soil degradation predominantly arises from wind erosion. Trends in soil degradation caused by wind erosion in northern China frequently change with human activities and climatic change. To decrease soil loss by wind erosion and enhance local ecosystems, the Chinese government has been encouraging residents to reduce wind-induced soil degradation through a series of national policies and several ecological projects, such as the Natural Forest Protection Program, the National Action Program to Combat Desertification, the “Three Norths” Shelter Forest System, the Beijing-Tianjin Sand Source Control Engineering Project, and the Grain for Green Project. All these were implemented a number of decades ago, and have thus created many land management practices and control techniques across different landscapes. These measures include conservation tillage, windbreak networks, checkerboard barriers, the Non-Watering and Tube-Protecting Planting Technique, afforestation, grassland enclosures, etc. As a result, the aeolian degradation of land has been controlled in many regions of arid and semiarid northern China. However, the challenge of mitigating and further reversing soil degradation caused by wind erosion still remains.

Clear cutting (10-13th century) and deep stable economy (18-19th century) as responsible interventions for sand drifting and plaggic deposition in cultural landscapes on aeolian sands (SE-Netherlands).

Science.gov (United States)

van Mourik, Jan; Vera, Hein; Wallinga, Jakob

2013-04-01

landscapes, characterized by deflation plains (gleyic arenosols) and complexes of inland dunes (haplic arenosols). Clear cutting was responsible for the mediaeval first large scale expansion of drift sand landscapes. In such driftsand landscapes, the majority of the podzolic soils in coversand has been truncated by aeolian erosion. Only on scattered sheltered sites in the landscape, palaeopodzols were buried under mono or polycyclic driftsand deposits. They are now the valuable soil archives for palaeoecological research. During the 18th century, the population growth and regional economic activity stimulated the agricultural productivity. Farmers introduced the innovative 'deep stable' technique to increase the production of fertilizers. Farmers started sod digging, including the top of the Ah horizon of the humus forms. This consequently promoted heath degradation and sand drifting, resulting in the extension of driftsand landscapes. Deep stable economy and sod digging was responsible for the 18th century second large scale expansion of drift sand landscapes. During the 19th century, farmers tried to find alternative fertilizers and authorities initiated reforestation projects. The invention of chemical fertilizers at the end of the 19th century marked the end of the period of heath management and plaggic agriculture. The heath was no longer used for the harvesting of plaggic matter and new land management practices were introduced. Heath was reclaimed to new arable land or reforested with Scotch pine. Geomorphological features as inland dunes and plaggic covers survived in the landscape and are now included in the geological inheritance.

Punctuated sediment record resulting from channel migration in a shallow sand-dominated micro-tidal lagoon, Northern Wadden Sea, Denmark

DEFF Research Database (Denmark)

Fruergaard, M.; Andersen, T.J.; Nielsen, L.H.

2011-01-01

depositional environment, but tidal channel sediments dominate in the five sediment cores, making up 56% of the 15 mof sediment core. Sedimentation in the lagoon alternated between slow vertical aggradation of sand flats (1.5–2 mm yr-1) and very fast lateral progradation of point bars in tidal channels, which...... caused the formation of a punctuated lagoonal fill. Frequent and comprehensive reworking of the sand flat sediments by tidal channel migration entails loss of sedimentary structures and bioturbation related to sand flat deposits, and old sand flat sediments are only very sparsely preserved. We further...... conclude that long-term (millennial timescale) sediment accumulation in the lagoon was controlled by rising sea-level, whereas short-term (centurial timescale) sediment accumulation was controlled by local erosion and depositional events caused by lateral migration of channels. Records of short-term sea...

Sand Needs and Resources Offshore New York

Science.gov (United States)

Lashley, J. M.; Flood, R. D.; White, M.; Bokuniewicz, H.; Hinrichs, C.; Wilson, R. E.

2016-02-01

"Superstorm" Sandy (October, 2012) accentuated the persistent problem of coastal erosion on New York's ocean coast. The New York state Department of State in cooperation with the Bureau of Ocean Energy Management has initiated further identification and assessment of marine sand reserves required to improve the resiliency of coastal communities and the maintenance of coastal habitats. The historical demand for beach nourishment has been about 1.5 million cubic meters per year, but sea level rise and the occurrence of extreme conditions may increase the demand to over 5 million cubic meters annually. Forty-four historical and proposed borrow sites have been delineated. This inner shelf is both sand rich and data rich. Geophysical and geological data has been compiled and reassessed to support identification, characterization, and delineation of sand resources for potential use in future coastal restoration, beach nourishment, and/or wetland restoration efforts. The South Shore of Long Island is composed in part by the Fire Island National Seashore. Holocene sand ridges extending at an oblique angle to the cross shore in the seaward direction. Borrow pits among the sand ridges, excavated were apparent in the most recent surveys and it appears that natural replenishment of offshore borrow areas has been occurring although the rates need to be determined in order to assess their sustainability. Not only is the area one of intense societal attention, but the use of this resource for coastal resilience must fit into a diverse framework marine spatial planning including not only traditional components, like commercial fishing, but also new factors like the siting of offshore wind-farms. To extend this assessment will include a recent survey, sponsored by the Bureau of Ocean Energy Management and the New York Department of State, providing approximately 700 km of geophysical survey lines located between 3 and 9 nautical miles offshore, and 46 geotechnical samples

Harding - a field case study: Sand control strategy for ultra-high productivity and injectivity wells

Energy Technology Data Exchange (ETDEWEB)

McKay, G.; Bennett, C.; Price-Smith, C.; Dowell, S.; McLellan, W. [British Petroleum (United Kingdom)

1998-12-31

The strategy adopted and the factors considered in the development of the sandface completion design for Phase One of the Harding Field in the unconsolidated Balder Massive Sand in the U.K. Sector of the North Sea is described. The field development utilizes a TPG 500 Jack-up Drilling and Production Unit in conjunction with a concrete gravity base tank (GBT). The first phase of the development involved drilling and completing horizontal wells sand-free, ultra-high production (over 30,000 BOPD/well, with PI in excess of 1,000 bbl/day/psi). The experiences showed that pre-packed screens can be successfully utilized to provide lasting sand control with high rate of production in clean homogenous sandstones, and that testing for fluid compatibility, formation damage, screen plugging, corrosion and erosion potential are essential pre-requisites in determining the optimal solution in any well with sand production potential.The experiences gained in Phase One have contributed to design enhancements for Phase Two of the project which include extended reach horizontal wells to neighbouring satellite pools. 3 refs., 1 tab., 8 figs.

Advancements in Hydrology and Erosion Process Understanding and Post-Fire Hydrologic and Erosion Model Development for Semi-Arid Landscapes

Science.gov (United States)

Williams, C. Jason; Pierson, Frederick B.; Al-Hamdan, Osama Z.; Robichaud, Peter R.; Nearing, Mark A.; Hernandez, Mariano; Weltz, Mark A.; Spaeth, Kenneth E.; Goodrich, David C.

2017-04-01

Fire activity continues to increase in semi-arid regions around the globe. Private and governmental land management entities are challenged with predicting and mitigating post-fire hydrologic and erosion responses on these landscapes. For more than a decade, a team of scientists with the US Department of Agriculture has collaborated on extensive post-fire hydrologic field research and the application of field research to development of post-fire hydrology and erosion predictive technologies. Experiments funded through this research investigated the impacts of fire on vegetation and soils and the effects of these fire-induced changes on infiltration, runoff generation, erodibility, and soil erosion processes. The distribution of study sites spans diverse topography across grassland, shrubland, and woodland landscapes throughout the western United States. Knowledge gleaned from the extensive field experiments was applied to develop and enhance physically-based models for hillslope- to watershed-scale runoff and erosion prediction. Our field research and subsequent data syntheses have identified key knowledge gaps and challenges regarding post-fire hydrology and erosion modeling. Our presentation details some consistent trends across a diverse domain and varying landscape conditions based on our extensive field campaigns. We demonstrate how field data have advanced our understanding of post-fire hydrology and erosion for semi-arid landscapes and highlight remaining key knowledge gaps. Lastly, we briefly show how our well-replicated experimental methodologies have contributed to advancements in hydrologic and erosion model development for the post-fire environment.

Urine metabolic profiling for the pathogenesis research of erosive oral lichen planus.

Science.gov (United States)

Li, Xu-Zhao; Yang, Xu-Yan; Wang, Yu; Zhang, Shuai-Nan; Zou, Wei; Wang, Yan; Li, Xiao-Nan; Wang, Ling-Shu; Zhang, Zhi-Gang; Xie, Liang-Zhen

2017-01-01

Oral lichen planus (OLP) is a relatively common chronic immune-pathological and inflammatory disease and potentially oral precancerous lesion. Erosive OLP patients show the higher rate of malignant transformation than patients with non-erosive OLP. Identifying the potential biomarkers related to erosive OLP may help to understand the pathogenesis of the diseases. Metabolic profiles were compared in control and patient subjects with erosive OLP by using ultra-performance liquid chromatography-quadrupole time-of-flight-mass spectrometry (UPLC-QTOF-MS) coupled with pattern recognition methods An integrative analysis was used to identify the perturbed metabolic pathways and pathological processes that may be associated with the disease. In total, 12 modulated metabolites were identified and considered as the potential biomarkers of erosive OLP. Multiple metabolic pathways and pathological processes were involved in erosive OLP. The dysregulations of these metabolites could be used to explain the pathogenesis of the disease, which could also be the potential therapeutic targets for the disease. Copyright © 2016 Elsevier Ltd. All rights reserved.

Linking rapid erosion of the Mekong River delta to human activities.

Science.gov (United States)

Anthony, Edward J; Brunier, Guillaume; Besset, Manon; Goichot, Marc; Dussouillez, Philippe; Nguyen, Van Lap

2015-10-08

As international concern for the survival of deltas grows, the Mekong River delta, the world's third largest delta, densely populated, considered as Southeast Asia's most important food basket, and rich in biodiversity at the world scale, is also increasingly affected by human activities and exposed to subsidence and coastal erosion. Several dams have been constructed upstream of the delta and many more are now planned. We quantify from high-resolution SPOT 5 satellite images large-scale shoreline erosion and land loss between 2003 and 2012 that now affect over 50% of the once strongly advancing >600 km-long delta shoreline. Erosion, with no identified change in the river's discharge and in wave and wind conditions over this recent period, is consistent with: (1) a reported significant decrease in coastal surface suspended sediment from the Mekong that may be linked to dam retention of its sediment, (2) large-scale commercial sand mining in the river and delta channels, and (3) subsidence due to groundwater extraction. Shoreline erosion is already responsible for displacement of coastal populations. It is an additional hazard to the integrity of this Asian mega delta now considered particularly vulnerable to accelerated subsidence and sea-level rise, and will be exacerbated by future hydropower dams.

Effects of erosion control structures along a portion of the northern Chesapeake Bay shoreline

Science.gov (United States)

Zabawa, C.F.; Kerhin, R.T.; Bayley, S.

1981-01-01

A 6.500-meter reach of western Chesapeake Bay shoreline (lower Mayo Peninsula) lost about 1.1??106 cubic meters of sediment (equivalent to 170 cubic meters lost per meter of shoreline) between 1846 and 1932, when the first aerial photographs show the shoreline already substantially protected by a system of groins and intermittent bulkheading. These structures have eliminated the fastland as a source of erodable material, and have starved the supply of sand for littoral drift, thus limiting the extent of the beaches to the remaining groin fields. Volumes of sediment involved in these impacts are small in the overall sediment budget. Bulkheads produce no deficit in the budget since scouring of the beaches on their seaward sides makes up for the decreased erosion of protected fastland. Groins trap little of the potential littoral drift (computed to be about 104 cubic meters per meter of shoreline per year). The sand supply in the remaining beaches is nearly equivalent to the annual loss of sediment from the entire shoreline system due to the long-term rate of erosion of the shoreline and nearshore between 1846 and 1932. ?? 1981 Springer-Verlag New York Inc.

Runoff erosion

OpenAIRE

Evelpidou, Niki (Ed.); Cordier, Stephane (Ed.); Merino, Agustin (Ed.); Figueiredo, Tomás de (Ed.); Centeri, Csaba (Ed.)

2013-01-01

Table of Contents PART I – THEORY OF RUNOFF EROSION CHAPTER 1 - RUNOFF EROSION – THE MECHANISMS CHAPTER 2 - LARGE SCALE APPROACHES OF RUNOFF EROSION CHAPTER 3 - MEASURING PRESENT RUNOFF EROSION CHAPTER 4 - MODELLING RUNOFF EROSION CHAPTER 5 - RUNOFF EROSION AND HUMAN SOCIETIES: THE INFLUENCE OF LAND USE AND MANAGEMENT PRACTICES ON SOIL EROSION PART II - CASE STUDIES CASE STUDIES – INTRODUCTION: RUNOFF EROSION IN MEDITERRANEAN AREA CASE STUDY 1: Soil Erosion Risk...

EFFECTS OF SLOPE SHAPES ON SOIL EROSION

Directory of Open Access Journals (Sweden)

Hüseyin ŞENSOY, Şahin PALTA

2009-01-01

Full Text Available Water is one of the most important erosive forces. A great number of factors also play a role in erosion process and slope characteristic is also one of them. The steepness and length of the slope are important factors for runoff and soil erosion. Another slope factor that has an effect on erosion is the shape of the slope. Generally, different erosion and runoff characteristics exist in different slopes which can be classified as uniform, concave, convex and complex shape. In this study, the effects of slope shape on erosion are stated and emphasized by taking similar researches into consideration.

Rapid reservoir erosion, hyperconcentrated flow, and downstream deposition triggered by breaching of 38 m tall Condit Dam, White Salmon River, Washington

Science.gov (United States)

Wilcox, Andrew C.; O'Connor, James E.; Major, Jon J.

2014-01-01

Condit Dam on the White Salmon River, Washington, a 38 m high dam impounding a large volume (1.8 million m3) of fine-grained sediment (60% sand, 35% silt and clay, and 5% gravel), was rapidly breached in October 2011. This unique dam decommissioning produced dramatic upstream and downstream geomorphic responses in the hours and weeks following breaching. Blasting a 5 m wide hole into the base of the dam resulted in rapid reservoir drawdown, abruptly releasing ~1.6 million m3 of reservoir water, exposing reservoir sediment to erosion, and triggering mass failures of the thickly accumulated reservoir sediment. Within 90 min of breaching, the reservoir's water and ~10% of its sediment had evacuated. At a gauging station 2.3 km downstream, flow increased briefly by 400 m3 s−1during passage of the initial pulse of released reservoir water, followed by a highly concentrated flow phase—up to 32% sediment by volume—as landslide-generated slurries from the reservoir moved downstream. This hyperconcentrated flow, analogous to those following volcanic eruptions or large landslides, draped the downstream river with predominantly fine sand. During the ensuing weeks, suspended-sediment concentration declined and sand and gravel bed load derived from continued reservoir erosion aggraded the channel by >1 m at the gauging station, after which the river incised back to near its initial elevation at this site. Within 15 weeks after breaching, over 1 million m3 of suspended load is estimated to have passed the gauging station, consistent with estimates that >60% of the reservoir's sediment had eroded. This dam removal highlights the influence of interactions among reservoir erosion processes, sediment composition, and style of decommissioning on rate of reservoir erosion and consequent downstream behavior of released sediment.

Numerical Analysis Study of Sarawak Barrage River Bed Erosion and Scouring by Using Smooth Particle Hydrodynamic (SPH)

Science.gov (United States)

Zainol, M. R. R. M. A.; Kamaruddin, M. A.; Zawawi, M. H.; Wahab, K. A.

2017-11-01

Smooth Particle Hydrodynamic is the three-dimensional (3D) model. In this research work, three cases and one validation have been simulate using DualSPHysics. Study area of this research work was at Sarawak Barrage. The cases have different water level at the downstream. This study actually to simulate riverbed erosion and scouring properties by using multi-phases cases which use sand as sediment and water. The velocity and the scouring profile have been recorded as the result and shown in the result chapter. The result of the validation is acceptable where the scouring profile and the velocity were slightly different between laboratory experiment and simulation. Hence, it can be concluded that the simulation by using SPH can be used as the alternative to simulate the real cases.

Direct Chlorination of Zircon Sand

International Nuclear Information System (INIS)

Dwiretnani Sudjoko; Budi Sulistyo; Pristi Hartati; Sunardjo

2002-01-01

It was investigated the direct chlorination of zircon sand in a unit chlorination equipment. The process was in semi batch. The product gas was scrubbed in aqueous NaOH. It was search the influence of time, ratio of reactant and size of particle sand to the concentration of Zr and Si in the product. From these research it was found that as the times, ratio of reactant increased, the concentration of Zr increased, but the concentration of Si decreased, while as grain size of zircon sand decreased the concentration of Zr decreased, but the concentration of Si increased. (author)

Remote Sensing techniques used to characterize soil erosion in southwestern Sao Paulo state. M.S. Thesis - 29 Sep. 1982; [Brazil

Science.gov (United States)

Parada, N. D. J. (Principal Investigator); Pinto, S. D. A. F.

1983-01-01

Within randomly sampled squares of a 1 km x 1 km grid, rill/gullies frequency, land cover/land use type and shape of the slopes were extracted from aerial photographs of the Ribeirao Anhumas drainage basin. Mean slope gradient, stream frequency and slope length were calculated on topographic maps. Ground truth data on fine sand/coarse sand ratio and vegetation cover densities were obtained. The MSS-LANDSAT-2 data (CCTs) were analyzed using single-cell, cluster synthesis and slicer algorithms. Graphical and statistical analyses of the data indicate that different slope gradients and land cover/land use types are the most significant factors related to the soil erosion process. The digital analysis of MSS data allowed the association among gray level classes and vegetation cover classes, which defined seven classes. These gray level classes and slope gradient classes were used to rank erosion risk.

Evaluate of head loss, sediment value and copper removal in sand media (rapid sand filter

Directory of Open Access Journals (Sweden)

Daneshi Navab

2014-06-01

Full Text Available Along with the technology development and increasing consumption of water resources, we are experiencing low qualities in the mentioned resources. Copper brings about serious environment al pollution, threatening human health and ecosystem. This metal found variously in water resources and industrial activities. Therefore, it needs to treat the water resources from these excessive amounts. Different methods have used for this reason but the most used method during recent years has been the absorption by economic absorbers such as sand. Rapid sand filters usually used in water and wastewater treatment plants for water clarification. In this research, a single layer gravity rapid sand filter has used to reduce different concentrations of copper. sediment value and head loss arising in filter media is simulated by using combination of Carman-Kozeny, Rose and Gregory models in different discharges of rapid sand filter. Results have shown that with increasing in discharge and decreasing in input copper concentration, arriving time to given head loss, is increasing. In addition, results demonstrated that with increasing in copper concentration in influent, removal efficiency is decreasing somewhat. Results of this research can applied in an appropriate design of rapid sand filter to copper removal, a prediction of rapid sand filter ability to copper removal and an estimation of arising head loss during filter work thus evaluating of time interval backwash. DOI: http://dx.doi.org/10.3126/ije.v3i2.10641 International Journal of the Environment Vol.3(2 2014: 276-286

The June 2016 Australian East Coast Low: Importance of Wave Direction for Coastal Erosion Assessment

Directory of Open Access Journals (Sweden)

Thomas R. Mortlock

2017-02-01

Full Text Available In June 2016, an unusual East Coast Low storm affected some 2000 km of the eastern seaboard of Australia bringing heavy rain, strong winds and powerful wave conditions. While wave heights offshore of Sydney were not exceptional, nearshore wave conditions were such that beaches experienced some of the worst erosion in 40 years. Hydrodynamic modelling of wave and current behaviour as well as contemporaneous sand transport shows the east to north-east storm wave direction to be the major determinant of erosion magnitude. This arises because of reduced energy attenuation across the continental shelf and the focussing of wave energy on coastal sections not equilibrated with such wave exposure under the prevailing south-easterly wave climate. Narrabeen–Collaroy, a well-known erosion hot spot on Sydney’s Northern Beaches, is shown to be particularly vulnerable to storms from this direction because the destructive erosion potential is amplified by the influence of the local embayment geometry. We demonstrate the magnified erosion response that occurs when there is bi-directionality between an extreme wave event and preceding modal conditions and the importance of considering wave direction in extreme value analyses.

Effectiveness of conservation agriculture practices on soil erosion processes in semi-arid areas of Zimbabwe

Science.gov (United States)

Chikwari, Emmanuel; Mhaka, Luke; Gwandu, Tariro; Chipangura, Tafadzwa; Misi Manyanga, Amos; Sabastian Matsenyengwa, Nyasha; Rabesiranana, Naivo; Mabit, Lionel

2016-04-01

- The application of fallout radionuclides (FRNs) in soil erosion and redistribution studies has gained popularity since the late 1980s. In Zimbabwe, soil erosion research was mostly based on conventional methods which included the use of erosion plots for quantitative measurements and erosion models for predicting soil losses. Only limited investigation to explore the possibility of using Caesium-137 (Cs-137) has been reported in the early 1990s for undisturbed and cultivated lands in Zimbabwe. In this study, the Cs-137 technique was applied to assess the impact of soil conservation practices on soil losses and to develop strategies and support effective policies that help farmers in Zimbabwe for sustainable land management. The study was carried out at the Makoholi research station 30 km north of the Masvingo region which is located 260 km south of Harare. The area is semi-arid and the study site comprises coarse loamy sands, gleyic lixisols. The conservation agriculture (CA) practices used within the area since 1988 include (i) direct seeding (DS) with mulch, (ii) CA basins with mulch, and (iii) 18 years direct seeding, left fallow for seven years and turned into conventional tillage since 2012 (DS/F/C). The Cs-137 reference inventory was established at 214 ± 16 Bq/m2. The mean inventories for DS, CA basins and DS/F/C were 195, 190 and 214 Bq/m2 respectively. Using the conversion Mass Balance Model 2 on the Cs-137 data obtained along transects for each of the practices, gross erosion rates were found to be 7.5, 7.3 and 2.6 t/ha/yr for direct seeding, CA basins and the DS/F/C while the net erosion rates were found to be 3.8, 4.6 and 0 t/ha/yr respectively. Sediment delivery ratios were 50%, 63% and 2% in the respective order. These preliminary results showed the effectiveness of DS over CA basins in erosion control. The efficiency of fallowing in controlling excessive soil loss was significant in the plot that started as DS for 18 years but left fallow for 7

Contemporary sand wedge development in seasonally frozen ground and paleoenvironmental implications

Science.gov (United States)

Wolfe, Stephen A.; Morse, Peter D.; Neudorf, Christina M.; Kokelj, Steven V.; Lian, Olav B.; O'Neill, H. Brendan

2018-05-01

Contemporary sand wedges and sand veins are active in seasonally frozen ground within the extensive discontinuous permafrost zone in Northwest Territories, Canada. The region has a subarctic continental climate with 291 mm a-1 precipitation, -4.1 °C mean annual air temperature, warm summers (July mean 17.0 °C), and cold winters (January mean -26.6 °C). Five years of continuous observations indicate that interannual variation of the ground thermal regime is dominantly controlled by winter air temperature and snow cover conditions. At sandy sites, thin snow cover and high thermal conductivity promote rapid freezing, high rates of ground cooling, and low near-surface ground temperatures (-15 to -25 °C), resulting in thermal contraction cracking to depths of 1.2 m. Cracking potentials are high in sandy soils when air temperatures are air temperatures are ≤-17 °C, and snow cover is conditions in peatlands maintain permafrost, but thermal contraction cracking does not occur because thicker snow cover and the thermal properties of peat prolong freezeback and maintain higher winter ground temperatures. A combination of radiocarbon dating, optical dating, and stratigraphic observations were used to differentiate sand wedge types and formation histories. Thermal contraction cracks that develop in the sandy terrain are filled by surface (allochthonous) and/or host (autochthonous) material during the thaw season. Epigenetic sand wedges infilled with allochthonous sand develop within former beach sediments beneath an active eolian sand sheet. Narrower and deeper syngenetic wedges developed within aggrading eolian sand sheets, whereas wider and shallower antisyngenetic wedges developed in areas of active erosion. Thermal contraction cracking beneath vegetation-stabilized surfaces leads to crack infilling by autochthonous host and overlying organic material, with resultant downturning and subsidence of adjacent strata. Sand wedge development in seasonally frozen ground

Saliva and dental erosion.

Science.gov (United States)

Buzalaf, Marília Afonso Rabelo; Hannas, Angélicas Reis; Kato, Melissa Thiemi

2012-01-01

Dental erosion is a multifactorial condition. The consideration of chemical, biological and behavioral factors is fundamental for its prevention and therapy. Among the biological factors, saliva is one of the most important parameters in the protection against erosive wear. This review discusses the role of salivary factors on the development of dental erosion. A search was undertaken on MeDLINe website for papers from 1969 to 2010. The keywords used in the research were "saliva", "acquired pellicle", "salivary flow", "salivary buffering capacity" and "dental erosion". Inclusion of studies, data extraction and quality assessment were undertaken independently and in duplicate by two members of the review team. Disagreements were solved by discussion and consensus or by a third party. Several characteristics and properties of saliva play an important role in dental erosion. Salivary clearance gradually eliminates the acids through swallowing and saliva presents buffering capacity causing neutralization and buffering of dietary acids. Salivary flow allows dilution of the acids. In addition, saliva is supersaturated with respect to tooth mineral, providing calcium, phosphate and fluoride necessary for remineralization after an erosive challenge. Furthermore, many proteins present in saliva and acquired pellicle play an important role in dental erosion. Saliva is the most important biological factor affecting the progression of dental erosion. Knowledge of its components and properties involved in this protective role can drive the development of preventive measures targeting to enhance its known beneficial effects.

Saliva and dental erosion

Directory of Open Access Journals (Sweden)

Marília Afonso Rabelo Buzalaf

2012-10-01

Full Text Available Dental erosion is a multifactorial condition. The consideration of chemical, biological and behavioral factors is fundamental for its prevention and therapy. Among the biological factors, saliva is one of the most important parameters in the protection against erosive wear. Objective: This review discusses the role of salivary factors on the development of dental erosion. Material and Methods: A search was undertaken on MeDLINe website for papers from 1969 to 2010. The keywords used in the research were "saliva", "acquired pellicle", "salivary flow", "salivary buffering capacity" and "dental erosion". Inclusion of studies, data extraction and quality assessment were undertaken independently and in duplicate by two members of the review team. Disagreements were solved by discussion and consensus or by a third party. Results: Several characteristics and properties of saliva play an important role in dental erosion. Salivary clearance gradually eliminates the acids through swallowing and saliva presents buffering capacity causing neutralization and buffering of dietary acids. Salivary flow allows dilution of the acids. In addition, saliva is supersaturated with respect to tooth mineral, providing calcium, phosphate and fluoride necessary for remineralization after an erosive challenge. Furthermore, many proteins present in saliva and acquired pellicle play an important role in dental erosion. Conclusions: Saliva is the most important biological factor affecting the progression of dental erosion. Knowledge of its components and properties involved in this protective role can drive the development of preventive measures targeting to enhance its known beneficial effects.

Evaluation of the 137Cs technique for estimating wind erosion losses for some sandy Western Australian soils

International Nuclear Information System (INIS)

Harper, R.J.; Gilkes, R.J.

1994-01-01

The utility of the caesium-137 technique, for estimating the effects of wind erosion, was evaluated on the soils of a semi-arid agricultural area near Jerramungup, Western Australia. The past incidence of wind erosion was estimated from field observations of soil profile morphology and an existing remote sensing study. Erosion was limited to sandy surfaced soils (0-4% clay), with a highly significant difference (P 137 Cs values between eroded and non-eroded sandy soils, with mean values of 243±17 and 386±13 Bq m -2 respectively. Non-eroded soils, with larger clay contents, had a mean 137 Cs content of 421±26 Bq m -2 , however, due to considerable variation between replicate samples, this value was not significantly different from that of the non-eroded sands. Hence, although the technique discriminates between eroded and non-eroded areas, the large variation in 137 Cs values means that from 27 to 96 replicate samples are required to provide statistically valid estimates of 137 Cs loss. The occurrence of around 18% of the total 137 Cs between 10 and 20 cm depth in these soils, despite cultivation being confined to the surface 9 cm, suggests that leaching of 137 Cs occurs in the sandy soils, although there was no relationship between clay content and 137 Cs value for either eroded or non-eroded soils. In a multiple linear regression, organic carbon content and the mean grain size of the eroded soils explained 35% of the variation in 137 Cs content. This relationship suggests that both organic carbon and 137 Cs are removed by erosion, with erosion being more prevalent on soils with a finer sand fraction. Clay and silt contents do not vary with depth in the near-surface horizons of the eroded sandy soils, hence it is likely that wind erosion strips the entire surface horizon with its 137 Cs content, rather than selectively winnowing fine material. 71 refs., 6 tabs., 2 fig

Dose rates of beach sands along the Enshu-nada coast

International Nuclear Information System (INIS)

Minato, Susumu; Shimo, Michikuni

2014-01-01

In order to understand the mechanism of beach-to-beach variations in dose rates, measurements at 35 sand beaches were carried out along the Enshu-nada coast (a total of 140km). The sand samples were collected at 10 beaches to obtain the concentrations of potassium, uranium and thorium by means of Ge(Li) spectroscopy. Factors affecting the variation in dose rates were discussed, incorporating these data with data of coastal sea-bottom sediments taken by the Geological Survey of Japan. Two-dimensional measurements were performed at 50 locations each in two beaches near the Tenryu river mouth to know within-beach variations in detail. Contour maps of the data revealed a considerable regularity. It was found from simple analyses of the data collected in this work that the dose rate levels at beaches are affected by the distance from the river mouth, erosion or sedimentation of beach, and depth distribution of seawater. (author)

Soil dynamics and accelerated erosion: a sensitivity analysis of the LPJ Dynamic vegetation model

Science.gov (United States)

Bouchoms, Samuel; Van Oost, Kristof; Vanacker, Veerle; Kaplan, Jed O.; Vanwalleghem, Tom

2013-04-01

pools and/or the surface pools vary with sand and silt richness, the highest values being reached with a combination of 50% silt and 25% sand while the lowest are for a 100% clay soil. Finally, LPJ is run for three cases corresponding to a stable, erosive and depositional soil profile. These simulations show how the model reacts and performs under erosion/deposition conditions which are recreated by changing the soil's texture and soil depth over time. We discuss the performance of the LPJ model in the context of accelerated erosion and conclusions drawn from the sensitivity analysis.

Uncertainties in assessing tillage erosion - How appropriate are our measuring techniques?

Science.gov (United States)

Fiener, P.; Wilken, F.; Aldana-Jague, E.; Deumlich, D.; Gómez, J. A.; Guzmán, G.; Hardy, R. A.; Quinton, J. N.; Sommer, M.; Van Oost, K.; Wexler, R.

2018-03-01

Tillage erosion on arable land is a very important process leading to a net downslope movement of soil and soil constitutes. Tillage erosion rates are commonly in the same order of magnitude as water erosion rates and can be even higher, especially under highly mechanized agricultural soil management. Despite its prevalence and magnitude, tillage erosion is still understudied compared to water erosion. The goal of this study was to bring together experts using different techniques to determine tillage erosion and use the different results to discuss and quantify uncertainties associated with tillage erosion measurements. The study was performed in northeastern Germany on a 10 m by 50 m plot with a mean slope of 8%. Tillage erosion was determined after two sequences of seven tillage operations. Two different micro-tracers (magnetic iron oxide mixed with soil and fluorescent sand) and one macro-tracer (passive radio-frequency identification transponders (RFIDs), size: 4 × 22 mm) were used to directly determine soil fluxes. Moreover, tillage induced changes in topography were measured for the entire plot with two different terrestrial laser scanners and an unmanned aerial system for structure from motion topography analysis. Based on these elevation differences, corresponding soil fluxes were calculated. The mean translocation distance of all techniques was 0.57 m per tillage pass, with a relatively wide range of mean soil translocation distances ranging from 0.39 to 0.72 m per pass. A benchmark technique could not be identified as all used techniques have individual error sources, which could not be quantified. However, the translocation distances of the macro-tracers used were consistently smaller than the translocation distances of the micro-tracers (mean difference = - 26 ± 12%), which questions the widely used assumption of non-selective soil transport via tillage operations. This study points out that tillage erosion measurements, carried out under almost

Environmental Impacts of Sand Exploitation. Analysis of Sand Market

Directory of Open Access Journals (Sweden)

Marius Dan Gavriletea

2017-06-01

Full Text Available Sand is an indispensable natural resource for any society. Despite society’s increasing dependence on sand, there are major challenges that this industry needs to deal with: limited sand resources, illegal mining, and environmental impact of sand mining. The purpose of this paper is twofold: to present an overview of the sand market, highlighting the main trends and actors for production, export and import, and to review the main environmental impacts associated with sand exploitation process. Based on these findings, we recommend different measures to be followed to reduce negative impacts. Sand mining should be done in a way that limits environmental damage during exploitation and restores the land after mining operations are completed.

Experimental study of the cavitation erosion in centrifugal pump impeller

International Nuclear Information System (INIS)

Rayan, M.A.

1985-01-01

Research on cavitation damage scale effects show that the damage rate is increased with size and velocity. It seems that for constant velocity there is no clear trend for the variation of erosion with cavitation number. Research on the time effects on damage rate show similarity between cavitation and impingement erosion. The cumulative weight loss versus time curve is of a ''S'' shaped type characterized by an incubation period followed by a period of increasing erosion rate, then a maximum erosion rate, and finally a period of decreasing erosion rate. The objective of this investigation is to present a prototype cavitation erosion experiment in order to clarify the time dependency of the erosive wear

Simulating Sand Behavior through Terrain Subdivision and Particle Refinement

Science.gov (United States)

Clothier, M.

2013-12-01

Advances in computer graphics, GPUs, and parallel processing hardware have provided researchers with new methods to visualize scientific data. In fact, these advances have spurred new research opportunities between computer graphics and other disciplines, such as Earth sciences. Through collaboration, Earth and planetary scientists have benefited by using these advances in hardware technology to process large amounts of data for visualization and analysis. At Oregon State University, we are collaborating with the Oregon Space Grant and IGERT Ecosystem Informatics programs to investigate techniques for simulating the behavior of sand. In addition, we have also been collaborating with the Jet Propulsion Laboratory's DARTS Lab to exchange ideas on our research. The DARTS Lab specializes in the simulation of planetary vehicles, such as the Mars rovers. One aspect of their work is testing these vehicles in a virtual "sand box" to test their performance in different environments. Our research builds upon this idea to create a sand simulation framework to allow for more complex and diverse environments. As a basis for our framework, we have focused on planetary environments, such as the harsh, sandy regions on Mars. To evaluate our framework, we have used simulated planetary vehicles, such as a rover, to gain insight into the performance and interaction between the surface sand and the vehicle. Unfortunately, simulating the vast number of individual sand particles and their interaction with each other has been a computationally complex problem in the past. However, through the use of high-performance computing, we have developed a technique to subdivide physically active terrain regions across a large landscape. To achieve this, we only subdivide terrain regions where sand particles are actively participating with another object or force, such as a rover wheel. This is similar to a Level of Detail (LOD) technique, except that the density of subdivisions are determined by

Khnifiss Beach's Black Sand: Provenance and Transport Pathways Investigation Using Heavy Minerals' Characterization

Science.gov (United States)

Adnani, M.; Elbelrhiti, H.; Ahmamou, M.; Masmoudi, L.

2014-12-01

Arid areas in south of Morocco suffer from silting problem causing destruction of villages infrastructure, roads, agriculture land and oasis heritage. Black sand on Khnifiss beach near Tarfaya city (S-W Morocco) is marked by enrichment of heavy minerals. This later is an important fraction that could help to assess the provenance and transport pathways of sediment. The sand's origin investigation could be useful to fight against erosion and silting problems from the source of supply, to this end, mineralogical analysis was carried out in Khnifiss beach's sand using Optic Microscope and Scanning Electronic Microscope with dispersive energy (SEM- EDS), in addition to physico-chemical analysis provided by Electronic Microprobe. The results revealed: (i) a high grade of oxides (Rutile, Ilmenite, Magnetite, Ulvöspinel) in samples, (ii) silicates (Quartz, Clinopyroxene, feldspar, Zircon), (iii) phosphate (apatite) and (iv) carbonate (calcite). The dominance of iron oxides justifies the black sand's colour. Then, the mineral composition supposes interference between different origins: proximal source (Calcareous cliff) for calcite, distal sources of oxides and silicates are supposed to be eroded and carried by Drâa valley from granite and igneous rocks in Anti-Atlasic field. Another source supposed might be a proximal volcanic island (Canaries island).

Coastal erosion and accretion rates in Greece

Science.gov (United States)

Foteinis, Spyros; Papadopoulos, Costas; Koutsogiannaki, Irini; Synolakis, Costas

2010-05-01

Erosion threatens many coastal regions of Greece. Anthropogenic changes of landforms such as coastal roads built on even narrow beaches, sand mining for construction, poor design of coastal structures that interfere with sediment, and dams without sediment bypasses have significantly reduced beach widths. We present erosion rates for different beaches, some of which are in sensitive ecosystems, otherwise "protected" by local and EU ordinances. By comparing inferences of beach widths in varying intervals from 1933 to 2006, we infer that the construction of dams in Acheloos river in western Greece, built in a faraonic attempt to partially divert its flows to eastern Greece, this is responsible for up to 20m/year erosion rates observed in certain locales in the Acheloos delta. More characteristic erosion rates in the region are ~ 2m/year. By contrast, there appears rapid accretion of up to 4m/year in the beaches around the Nestos delta in northern Greece (Papadopoulos, 2009). In beaches that are not near large river deltas, erosion rates range from 0.5m/year to 1m/year. While we have not done comprehensive comparisons among coastlines with different levels of coastal development, it does appear that rapid coastal development correlates well with erosion rates. The underlying problem is the complete lack of any semblance of coastal zone management in Greece and substandard design of coastal structures, which are often sited without any measurements of waves and currents offshore (Synolakis et al, 2008). Beach maintenance remains an exotic concept for most local authorities, who invariably prefer to build hard coastal structures to "protect" versus nourish, siting lack of experience with nourishment and "environmental" concerns. In certain cases, choices are dictated by costs, the larger the cost the easier the project gets approved by regulatory authorities, hence the preference for concrete or rubble structures. We conclude that, unless urgent salvage measures are

Extracting information on the spatial variability in erosion rate stored in detrital cooling age distributions in river sands

Science.gov (United States)

Braun, Jean; Gemignani, Lorenzo; van der Beek, Peter

2018-03-01

One of the main purposes of detrital thermochronology is to provide constraints on the regional-scale exhumation rate and its spatial variability in actively eroding mountain ranges. Procedures that use cooling age distributions coupled with hypsometry and thermal models have been developed in order to extract quantitative estimates of erosion rate and its spatial distribution, assuming steady state between tectonic uplift and erosion. This hypothesis precludes the use of these procedures to assess the likely transient response of mountain belts to changes in tectonic or climatic forcing. Other methods are based on an a priori knowledge of the in situ distribution of ages to interpret the detrital age distributions. In this paper, we describe a simple method that, using the observed detrital mineral age distributions collected along a river, allows us to extract information about the relative distribution of erosion rates in an eroding catchment without relying on a steady-state assumption, the value of thermal parameters or an a priori knowledge of in situ age distributions. The model is based on a relatively low number of parameters describing lithological variability among the various sub-catchments and their sizes and only uses the raw ages. The method we propose is tested against synthetic age distributions to demonstrate its accuracy and the optimum conditions for it use. In order to illustrate the method, we invert age distributions collected along the main trunk of the Tsangpo-Siang-Brahmaputra river system in the eastern Himalaya. From the inversion of the cooling age distributions we predict present-day erosion rates of the catchments along the Tsangpo-Siang-Brahmaputra river system, as well as some of its tributaries. We show that detrital age distributions contain dual information about present-day erosion rate, i.e., from the predicted distribution of surface ages within each catchment and from the relative contribution of any given catchment to the

Extracting information on the spatial variability in erosion rate stored in detrital cooling age distributions in river sands

Directory of Open Access Journals (Sweden)

J. Braun

2018-03-01

Full Text Available One of the main purposes of detrital thermochronology is to provide constraints on the regional-scale exhumation rate and its spatial variability in actively eroding mountain ranges. Procedures that use cooling age distributions coupled with hypsometry and thermal models have been developed in order to extract quantitative estimates of erosion rate and its spatial distribution, assuming steady state between tectonic uplift and erosion. This hypothesis precludes the use of these procedures to assess the likely transient response of mountain belts to changes in tectonic or climatic forcing. Other methods are based on an a priori knowledge of the in situ distribution of ages to interpret the detrital age distributions. In this paper, we describe a simple method that, using the observed detrital mineral age distributions collected along a river, allows us to extract information about the relative distribution of erosion rates in an eroding catchment without relying on a steady-state assumption, the value of thermal parameters or an a priori knowledge of in situ age distributions. The model is based on a relatively low number of parameters describing lithological variability among the various sub-catchments and their sizes and only uses the raw ages. The method we propose is tested against synthetic age distributions to demonstrate its accuracy and the optimum conditions for it use. In order to illustrate the method, we invert age distributions collected along the main trunk of the Tsangpo–Siang–Brahmaputra river system in the eastern Himalaya. From the inversion of the cooling age distributions we predict present-day erosion rates of the catchments along the Tsangpo–Siang–Brahmaputra river system, as well as some of its tributaries. We show that detrital age distributions contain dual information about present-day erosion rate, i.e., from the predicted distribution of surface ages within each catchment and from the relative contribution of

Erosive lichen planus: a therapeutic challenge.

Science.gov (United States)

Romero, Williams; Giesen, Laura; Navajas-Galimany, Lucas; Gonzalez, Sergio

2016-01-01

Erosive lichen planus is an uncommon variant of lichen planus. Chronic erosions of the soles, accompanied by intense and disabling pain, are some of its most characteristic manifestations. We present the case of a woman who developed oral and plantar erosive lichen planus associated with lichen planus pigmentosus and ungueal lichen planus that were diagnosed after several years. The patient failed to respond to multiple therapies requiring longstanding medication but remained refractory. Knowledge of the treatment options for erosive lichen planus is insufficient. Further research is required to clarify their effectiveness, ideally adopting an evidence-based methodology.

Relations between rainfall–runoff-induced erosion and aeolian deposition at archaeological sites in a semi-arid dam-controlled river corridor

Science.gov (United States)

Collins, Brian D.; Bedford, David; Corbett, Skye C.; Fairley, Helen C.; Cronkite-Ratcliff, Collin

2016-01-01

Process dynamics in fluvial-based dryland environments are highly complex with fluvial, aeolian, and alluvial processes all contributing to landscape change. When anthropogenic activities such as dam-building affect fluvial processes, the complexity in local response can be further increased by flood- and sediment-limiting flows. Understanding these complexities is key to predicting landscape behavior in drylands and has important scientific and management implications, including for studies related to paleoclimatology, landscape ecology evolution, and archaeological site context and preservation. Here we use multi-temporal LiDAR surveys, local weather data, and geomorphological observations to identify trends in site change throughout the 446-km-long semi-arid Colorado River corridor in Grand Canyon, Arizona, USA, where archaeological site degradation related to the effects of upstream dam operation is a concern. Using several site case studies, we show the range of landscape responses that might be expected from concomitant occurrence of dam-controlled fluvial sand bar deposition, aeolian sand transport, and rainfall-induced erosion. Empirical rainfall-erosion threshold analyses coupled with a numerical rainfall–runoff–soil erosion model indicate that infiltration-excess overland flow and gullying govern large-scale (centimeter- to decimeter-scale) landscape changes, but that aeolian deposition can in some cases mitigate gully erosion. Whereas threshold analyses identify the normalized rainfall intensity (defined as the ratio of rainfall intensity to hydraulic conductivity) as the primary factor governing hydrologic-driven erosion, assessment of false positives and false negatives in the dataset highlight topographic slope as the next most important parameter governing site response. Analysis of 4+ years of high resolution (four-minute) weather data and 75+ years of low resolution (daily) climate records indicates that dryland erosion is dependent on short

Modeling erosion and accretion along the Illinois Lake Michigan shore using integrated airborne, waterborne and ground-based method

Science.gov (United States)

Mwakanyamale, K. E.; Brown, S.; Larson, T. H.; Theuerkauf, E.; Ntarlagiannis, D.; Phillips, A.; Anderson, A.

2017-12-01

Sediment distribution at the Illinois Lake Michigan shoreline is constantly changing in response to increased human activities and complex natural coastal processes associated with wave action, short and long term fluctuations in lake level, and the influence of coastal ice. Understanding changes to volume, distribution and thickness of sand along the shore through time, is essential for modeling shoreline changes and predicting changes due to extreme weather events and lake-level fluctuation. The use of helicopter transient electromagnetic (HTEM) method and integration with ground-based and waterborne geophysical and geologic methods provides high resolution spatial rich data required for modeling the extent of erosion and accretion at this dynamic coastal system. Analysis and interpretation of HTEM, ground and waterborne geophysical and geological data identify spatial distribution and thickness of beach and lake-bottom sand. The results provide information on existence of littoral sand deposits and identify coastal hazards such as lakebed down-cutting that occurs in sand-starved areas.

Reservoir Sedimentation and Upstream Sediment Sources: Perspectives and Future Research Needs on Streambank and Gully Erosion

Science.gov (United States)

Fox, G. A.; Sheshukov, A.; Cruse, R.; Kolar, R. L.; Guertault, L.; Gesch, K. R.; Dutnell, R. C.

2016-05-01

The future reliance on water supply and flood control reservoirs across the globe will continue to expand, especially under a variable climate. As the inventory of new potential dam sites is shrinking, construction of additional reservoirs is less likely compared to simultaneous flow and sediment management in existing reservoirs. One aspect of this sediment management is related to the control of upstream sediment sources. However, key research questions remain regarding upstream sediment loading rates. Highlighted in this article are research needs relative to measuring and predicting sediment transport rates and loading due to streambank and gully erosion within a watershed. For example, additional instream sediment transport and reservoir sedimentation rate measurements are needed across a range of watershed conditions, reservoir sizes, and geographical locations. More research is needed to understand the intricate linkage between upland practices and instream response. A need still exists to clarify the benefit of restoration or stabilization of a small reach within a channel system or maturing gully on total watershed sediment load. We need to better understand the intricate interactions between hydrological and erosion processes to improve prediction, location, and timing of streambank erosion and failure and gully formation. Also, improved process-based measurement and prediction techniques are needed that balance data requirements regarding cohesive soil erodibility and stability as compared to simpler topographic indices for gullies or stream classification systems. Such techniques will allow the research community to address the benefit of various conservation and/or stabilization practices at targeted locations within watersheds.

Soil erosion as a driver of land-use change

NARCIS (Netherlands)

Bakker, M.M.; Govers, G.; Kosmas, C.; VanAcker, H.; Oost, van K.; Rounsevell, M.

2005-01-01

Although much research has been carried out on the crop productivity response to soil erosion, little is known about the role of soil erosion as a driver of land-use change. Given, however, the some-times large erosion-induced reductions in crop yields, it appears likely that erosion has a strong

137Cs use in estimating soil erosion: 30 years of research

International Nuclear Information System (INIS)

Ritchie, J.C.

1998-01-01

Significant amounts of fallout 137 Cs from nuclear weapons tests were introduced to the landscape during the 1950s and 1960s. Once 137 Cs reaches the soil surface it is strongly and quickly adsorbed by clay particles, and is essentially nonexchangeable in most environments. Thus, 137 Cs becomes and effective tracer of the movement of soil particles across the landscape. Over the past 30 years, researchers have shown that 137 Cs can be used to study soil movement. Early work used empirical relationships between soil loss and 137 Cs loss to estimate erosion. This was followed by the development of proportional and theoretical models to relate 137 Cs movement and soil redistribution. Most of the problems related to the 137 Cs technique are the same as those encountered with other techniques (i.e., sampling, measurement). The 137 Cs technique can make actual measurements of soil loss and redeposition in fields, fostering the formulation of better plans to conserve the quality of the landscape. This paper reviews the development of the 137 Cs technique to show how it can be used to understand erosion and soil movement on the landscape. (author)

Field testing, comparison, and discussion of five aeolian sand transport measuring devices operating on different measuring principles

Science.gov (United States)

Goossens, Dirk; Nolet, Corjan; Etyemezian, Vicken; Duarte-Campos, Leonardo; Bakker, Gerben; Riksen, Michel

2018-06-01

Five types of sediment samplers designed to measure aeolian sand transport were tested during a wind erosion event on the Sand Motor, an area on the west coast of the Netherlands prone to severe wind erosion. Each of the samplers operates on a different principle. The MWAC (Modified Wilson And Cooke) is a passive segmented trap. The modified Leatherman sampler is a passive vertically integrating trap. The Saltiphone is an acoustic sampler that registers grain impacts on a microphone. The Wenglor sampler is an optical sensor that detects particles as they pass through a laser beam. The SANTRI (Standalone AeoliaN Transport Real-time Instrument) detects particles travelling through an infrared beam, but in different channels each associated with a particular grain size spectrum. A procedure is presented to transform the data output, which is different for each sampler, to a common standard so that the samplers can be objectively compared and their relative efficiency calculated. Results show that the efficiency of the samplers is comparable despite the differences in operating principle and the instrumental and environmental uncertainties associated to working with particle samplers in field conditions. The ability of the samplers to register the temporal evolution of a wind erosion event is investigated. The strengths and weaknesses of the samplers are discussed. Some problems inherent to optical sensors are looked at in more detail. Finally, suggestions are made for further improvement of the samplers.

Japan's involvement in oil sands development

International Nuclear Information System (INIS)

Sugiura, T.

1994-01-01

According to Japanese national policy, exploration and development by Japanese companies in overseas countries are promoted in order to ensure stable oil supplies. Japan Canada Oil Sands Limited (JACOS), part of the JAPEX group, was established during the 1978 world oil crisis to explore and develop Canadian oil sand resources in accordance with Japan's national policy. The JAPEX group, including JACOS, has invested $123 million in oil sands projects in Alberta. JAPEX's first involvement in oil sands was in the Primrose Project operated by Norcen in the Cold Lake area. Five years of cyclic steam stimulation pilot tests did not produce sufficiently good results to justify further operation. The second involvement was the PCEJ Project, a joint effort by four companies that are participating in a bitumen recovery test project in the Athabasca Deposit. JACOS holds 2,452 km 2 of oil sands leases in Alberta. Tests conducted since 1978 in the PCEJ Project include multiwell steam injection pilot tests, some of which showed promise. JACOS is also participating in steam assisted gravity drainage projects and in federal/provincial research programs. Obstacles identified in developing Alberta oil sands are the lack of a bitumen pipeline to Edmonton and the insufficient length of oil sands leases (currently 10 years), given the difficulties of oil sand development. 10 figs

Factors of the Development of Water Erosion in the Zone of Recreation Activity in the Ol'khon Region

Science.gov (United States)

Znamenskaya, T. I.; Vanteeva, J. V.; Solodyankina, S. V.

2018-02-01

Specific features of water erosion of thin soils under conditions of nonpercolative water regime and intense recreational loads were studied in the Ol'khon region (Irkutsk oblast). An experiment on the transfer of terrigenous particles under the impact of rainfall simulation was performed. A thorough description of landscape characteristics affecting water erosion development was made. As a result, a multiple regression equation linking the transported matter with the slope steepness, projective cover of vegetation, the degree of vegetation degradation, and the fine sand content in the upper soil horizon was developed; the multiple correlation coefficient R reached 0.86. On this basis, the map of water erosion assessment for the study area was compiled with the use of landscape and topographic maps. The maximum intensity of water erosion is typical of the anthropogenically transformed landscapes on steep slopes with the low vegetative cover on the mountainous noncalcareous steppe soils and on thin loamy sandy surface-gravelly chestnut-like soils.

A Improved Seabed Surface Sand Sampling Device

Science.gov (United States)

Luo, X.

2017-12-01

In marine geology research it is necessary to obtain a suf fcient quantity of seabed surface samples, while also en- suring that the samples are in their original state. Currently,there are a number of seabed surface sampling devices available, but we fnd it is very diffcult to obtain sand samples using these devices, particularly when dealing with fne sand. Machine-controlled seabed surface sampling devices are also available, but generally unable to dive into deeper regions of water. To obtain larger quantities of seabed surface sand samples in their original states, many researchers have tried to improve upon sampling devices,but these efforts have generally produced ambiguous results, in our opinion.To resolve this issue, we have designed an improved andhighly effective seabed surface sand sampling device that incorporates the strengths of a variety of sampling devices. It is capable of diving into deepwater to obtain fne sand samples and is also suited for use in streams, rivers, lakes and seas with varying levels of depth (up to 100 m). This device can be used for geological mapping, underwater prospecting, geological engineering and ecological, environmental studies in both marine and terrestrial waters.

Computational and experimental study of effects of sediment shape on erosion of hydraulic turbines

International Nuclear Information System (INIS)

Poudel, L; Thapa, B; Shrestha, B P; Thapa, B S; Shrestha, K P; Shrestha, N K

2012-01-01

Hard particles as Quartz and Feldspar are present in large amount in most of the rivers across the Himalayan basins. In run-off-river hydro power plants these particles find way to turbine and cause its components to erode. Loss of turbine material due to the erosion and subsequent change in flow pattern induce several operational and maintenance problems in the power plants. Reduction in overall efficiency, vibrations and reduced life of turbine components are the major effects of sediment erosion of hydraulic turbines. Sediment erosion of hydraulic turbines is a complex phenomenon and depends upon several factors. One of the most influencing parameter is the characteristics of sediment particles. Quantity of sediment particles, which are harder than the turbine material, is one of the bases to indicate erosion potential of a particular site. Research findings have indicated that shape and size of the hard particles together with velocity of impact play a major role to decide the mode and rate of erosion in turbine components. It is not a common practice in Himalayan basins to conduct a detail study of sediment characteristics as a part of feasibility study for hydropower projects. Lack of scientifically verified procedures and guidelines to conduct the sediment analysis to estimate its erosion potential is one of the reasons to overlook this important part of feasibility study. Present study has been conducted by implementing computational tools to characterize the sediment particles with respect to their shape and size. Experimental studies have also been done to analyze the effects of different combinations of shape and size of hard particles on turbine material. Efforts have also been given to develop standard procedures to conduct similar study to compare erosion potential between different hydropower sites. Digital image processing software and sieve analyzer have been utilized to extract shape and size of sediment particles from the erosion sensitive power

Comparing Background and Recent Erosion Rates in Degraded Areas of Southeastern Brazil

Science.gov (United States)

Fernandes, N.; Bierman, P. R.; Sosa-Gonzalez, V.; Rood, D. H.; Fontes, R. L.; Santos, A. C.; Godoy, J. M.; Bhering, S.

2014-12-01

Soil erosion is a major problem in northwestern Rio de Janeiro State where, during the last three centuries, major land-use changes took place, associated with the replacement of the original rainforest by agriculture and grazing. The combination of steep hillslopes, erodible soils, sparse vegetation, natural and human-induced fires, as well as downslope ploughing, led to an increase in surface runoff and surface erosion on soil-mantled hillslopes; together, these actions and responses caused a decline in soil productivity. In order to estimate changes in erosion rates over time, we compared erosion rates measured at different spatial and temporal scales, both background (natural) and short-term (human-induced during last few decades). Background long-term erosion rates were measured using in-situ produced cosmogenic 10Be in the sand fraction quartz of active river channel sediment in four basins in the northwestern portion of Rio de Janeiro State. In these basins, average annual precipitation varies from 1,200 to 1,300 mm, while drainage areas vary from 15 to 7,200 km2. Short-term erosion rates were measured in one of these basins from fallout 210Pb in soil samples collected along a hillslope transect located in an abandoned agriculture field. In this transect, 190 undisturbed soil samples (three replicates) were collected from the surface to 0.50 m depth (5 cm vertical intervals) in six soil pits. 10Be average background, basin-wide, erosion rates in the area are ~ 13 m/My; over the last decades, time-integrated (210Pb) average hillslope erosion rates are around 1450 m/Myr, with maximum values at the steepest portion of convex hillslopes of about 2000 m/Myr. These results suggest that recent hillslope erosion rates are about 2 orders of magnitude above background rates of sediment generation integrated over many millennia. This unsustainable rate of soil loss has severely decreased soil productivity eventually leading to the abandonment of farming activities in

[Advance in researches on vegetation cover and management factor in the soil erosion prediction model].

Science.gov (United States)

Zhang, Yan; Yuan, Jianping; Liu, Baoyuan

2002-08-01

Vegetation cover and land management are the main limiting factors of soil erosion, and quantitative evaluation on the effect of different vegetation on soil erosion is essential to land use and soil conservation planning. The vegetation cover and management factor (C) in the universal soil loss equation (USLE) is an index to evaluate this effect, which has been studied deeply and used widely. However, the C factor study is insufficient in China. In order to strengthen the research of C factor, this paper reviewed the developing progress of C factor, and compared the methods of estimating C value in different USLE versions. The relative studies in China were also summarized from the aspects of vegetation canopy coverage, soil surface cover, and root density. Three problems in C factor study were pointed out. The authors suggested that cropland C factor research should be furthered, and its methodology should be unified in China to represent reliable C values for soil loss prediction and conservation planning.

Rheology of oil sands slurries

Energy Technology Data Exchange (ETDEWEB)

Chow, R.; Zhou, J. [Alberta Research Council, Edmonton, AB (Canada). Mineral Oil Sands Unit; Wallace, D. [Dean Wallace Consulting Inc., Beaumont, AB (Canada)

2006-07-01

This study focused on integrating rheology and colloid science to improve recovery of bitumen in surface mined oil sands. Factors that influence recovery, such as conditions of particle interaction, solids concentration and shear rate, were reviewed. In an effort to understand the rheological behaviour of clay-in-water suspensions, an elaborate procedure was developed to separate an inter-bedded clay layer from a site at Albian Sands Energy Inc. The variables were water chemistry, solids concentration, and shear rate. The research study was conducted at the Alberta Research Council with the support of the CONRAD Extraction Group. A controlled stress rheometer was used to provide the quantitative evaluations of the clay slurry properties. The research results indicate that the viscoelastic properties of the slurry are highly influenced by the shear history of the slurry, solids content, calcium concentration, and sample aging. Shear thinning behaviour was observed in all slurry samples, but the slurry viscosity increased with test time for a given shear rate. In order to classify the slurries, a method was developed to distinguish the gel strength. The slurries were then classified into 3 distinct patterns, including no gel, weak gel and strong gel. The evolution of the experimental protocols were described along with the current stability maps that correlate the domains of the gel strength according to the solids concentration, calcium ion content, and shear rate. It was concluded that the rheological properties of oil sands slurries influence bitumen recovery in commercial surface-mined oil sands operations. tabs., figs.

The extraction of bitumen from western oil sands

International Nuclear Information System (INIS)

Oblad, A.G.; Bunger, J.W.; Dahlstrom, D.A.; Deo, M.D.; Hanson, F.V.; Miller, J.D.; Seader, J.D.

1992-08-01

The University of Utah tar sand research and development program is concerned with research and development on Utah is extensive oil sands deposits. The program has been intended to develop a scientific and technological base required for eventual commercial recovery of the heavy oils from oil sands and processing these oils to produce synthetic crude oil and other products such as asphalt. The overall program is based on mining the oil sand, processing the mined sand to recover the heavy oils and upgrading them to products. Multiple deposits are being investigated since it is believed that a large scale (approximately 20,000 bbl/day) plant would require the use of resources from more than one deposit. The tasks or projects in the program are organized according to the following classification: Recovery technologies which includes thermal recovery methods, water extraction methods, and solvent extraction methods; upgrading and processing technologies which covers hydrotreating, hydrocracking, and hydropyrolysis; solvent extraction; production of specialty products; and environmental aspects of the production and processing technologies. These tasks are covered in this report

Dynamics of soil organic carbon and microbial biomass carbon in relation to water erosion and tillage erosion.

Science.gov (United States)

Xiaojun, Nie; Jianhui, Zhang; Zhengan, Su

2013-01-01

Dynamics of soil organic carbon (SOC) are associated with soil erosion, yet there is a shortage of research concerning the relationship between soil erosion, SOC, and especially microbial biomass carbon (MBC). In this paper, we selected two typical slope landscapes including gentle and steep slopes from the Sichuan Basin, China, and used the (137)Cs technique to determine the effects of water erosion and tillage erosion on the dynamics of SOC and MBC. Soil samples for the determination of (137)Cs, SOC, MBC and soil particle-size fractions were collected on two types of contrasting hillslopes. (137)Cs data revealed that soil loss occurred at upper slope positions of the two landscapes and soil accumulation at the lower slope positions. Soil erosion rates as well as distribution patterns of the erosion is the major process of soil redistribution in the gentle slope landscape, while tillage erosion acts as the dominant process of soil redistribution in the steep slope landscape. In gentle slope landscapes, both SOC and MBC contents increased downslope and these distribution patterns were closely linked to soil redistribution rates. In steep slope landscapes, only SOC contents increased downslope, dependent on soil redistribution. It is noticeable that MBC/SOC ratios were significantly lower in gentle slope landscapes than in steep slope landscapes, implying that water erosion has a negative effect on the microbial biomass compared with tillage erosion. It is suggested that MBC dynamics are closely associated with soil redistribution by water erosion but independent of that by tillage erosion, while SOC dynamics are influenced by soil redistribution by both water erosion and tillage erosion.

Using REE tracers to measure sheet erosion changing to rill erosion

International Nuclear Information System (INIS)

Liu Puling; Xue Yazhou; Song Wei; Wang Mingyi; Ju Tongjun

2004-01-01

Rare Earth Elements (REE) tracer method was used to study sheet erosion changing to rill erosion on slope land. By placing different rare earth elements of different soil depth across a slope in an indoor plot, two simulated rainfalls were applied to study the change of erosion type and the rill erosion process. The results indicate that the main erosion type is sheet erosion at the beginning of the rainfalls, and serious erosion happens after rill erosion appears. Accumulated sheet and rill erosion amounts increase with the rainfalls time. The percentage of sheet erosion amount decreases and rill erosion percentage increases with time. At the end of the rainfalls, the total rill erosion amounts are 4-5 times more than sheet erosion. In this paper, a new REE tracer method was used to quantitatively distinguish sheet and rill erosion amounts. The new REE tracer method should be useful to future studying of erosion processes on slope lands. (authors)

Western tight gas sands advanced logging workshop proceedings

Energy Technology Data Exchange (ETDEWEB)

Jennings, J B; Carroll, Jr, H B [eds.

1982-04-01

An advanced logging research program is one major aspect of the Western Tight Sands Program. Purpose of this workshop is to help BETC define critical logging needs for tight gas sands and to allow free interchange of ideas on all aspects of the current logging research program. Sixteen papers and abstracts are included together with discussions. Separate abstracts have been prepared for the 12 papers. (DLC)

Can we manipulate root system architecture to control soil erosion?

Science.gov (United States)

Ola, A.; Dodd, I. C.; Quinton, J. N.

2015-09-01

Soil erosion is a major threat to soil functioning. The use of vegetation to control erosion has long been a topic for research. Much of this research has focused on the above-ground properties of plants, demonstrating the important role that canopy structure and cover plays in the reduction of water erosion processes. Less attention has been paid to plant roots. Plant roots are a crucial yet under-researched factor for reducing water erosion through their ability to alter soil properties, such as aggregate stability, hydraulic function and shear strength. However, there have been few attempts to specifically manipulate plant root system properties to reduce soil erosion. Therefore, this review aims to explore the effects that plant roots have on soil erosion and hydrological processes, and how plant root architecture might be manipulated to enhance its erosion control properties. We demonstrate the importance of root system architecture for the control of soil erosion. We also show that some plant species respond to nutrient-enriched patches by increasing lateral root proliferation. The erosional response to root proliferation will depend upon its location: at the soil surface dense mats of roots may reduce soil erodibility but block soil pores thereby limiting infiltration, enhancing runoff. Additionally, in nutrient-deprived regions, root hair development may be stimulated and larger amounts of root exudates released, thereby improving aggregate stability and decreasing erodibility. Utilizing nutrient placement at specific depths may represent a potentially new, easily implemented, management strategy on nutrient-poor agricultural land or constructed slopes to control erosion, and further research in this area is needed.

Soil erosion in Slovene Istria

Directory of Open Access Journals (Sweden)

Matjaž Mikoš

2009-12-01

Full Text Available From the end of nineties of the 20th century, intense hydrologic and geomorphologic research is taking place in the Slovene Istria. As a part of this research also studies on soil erosion were undertaken in the period from 2005 to 2008. The field measurements were under taken onclosed 1m2 large erosion plots under three different land uses (on bare soils in an olive grove, on an overgrown meadow, in a forest, placed south of the Marezige village in the Rokava River basin.We show weekly measurements of surface erosion (interrill erosion for the period of 13 months (the end of March 2005 – the end of April 2006, as well as monthly and seasonal averages together with selected linear statistical correlations between soil erosion and weather parameters.From May 2005 to April 2006 the interrill erosion on bare soils in an olive grove with an inclination of 5.5° amounted to 9013 g/m2 (90 t/ha that corresponds to surface lowering rate of 8.5 mm/yr; on an overgrown meadow with an inclination of 9.4° it amounted to 168 g/m2 (1,68 t/ha that corresponds to surface lowering rate of 0.16 mm//yr; and in a forest with an inclination of 7.8° it amounted to 391 g/m2 (3,91 t/ha and in a forest with an inclination of 21.4° it amounted to 415 g/m2 (4,15 t/ha, respectively, that corresponds to surface lowering rate of 0.4 mm/yr.

Critical State of Sand Matrix Soils

Science.gov (United States)

Marto, Aminaton; Tan, Choy Soon; Makhtar, Ahmad Mahir; Kung Leong, Tiong

2014-01-01

The Critical State Soil Mechanic (CSSM) is a globally recognised framework while the critical states for sand and clay are both well established. Nevertheless, the development of the critical state of sand matrix soils is lacking. This paper discusses the development of critical state lines and corresponding critical state parameters for the investigated material, sand matrix soils using sand-kaolin mixtures. The output of this paper can be used as an interpretation framework for the research on liquefaction susceptibility of sand matrix soils in the future. The strain controlled triaxial test apparatus was used to provide the monotonic loading onto the reconstituted soil specimens. All tested soils were subjected to isotropic consolidation and sheared under undrained condition until critical state was ascertain. Based on the results of 32 test specimens, the critical state lines for eight different sand matrix soils were developed together with the corresponding values of critical state parameters, M, λ, and Γ. The range of the value of M, λ, and Γ is 0.803–0.998, 0.144–0.248, and 1.727–2.279, respectively. These values are comparable to the critical state parameters of river sand and kaolin clay. However, the relationship between fines percentages and these critical state parameters is too scattered to be correlated. PMID:24757417

Coastal Erosion and Flooding Hazards on the North Sea Coast at Thyboron, Denmark

DEFF Research Database (Denmark)

Sørensen, Per; Sørensen, Carlo Sass; Nielsen, Peter

Since a breach of the coastal barrier in 1862, the Thyboron Channel connecting the North Sea and the Lim Fiord has been artificially maintained by construction of breakwaters and groins on the North Sea coast and inside the channel, respectively. Sand nourishment schemes have since the 1980s coun...... counteracted the natural erosion in the upper profile on the North Sea coast where the alongshore sediment transport converges towards the channel and deposits up to 1 million m3/y on the flood tidal delta inside the fiord, Figure 1.......Since a breach of the coastal barrier in 1862, the Thyboron Channel connecting the North Sea and the Lim Fiord has been artificially maintained by construction of breakwaters and groins on the North Sea coast and inside the channel, respectively. Sand nourishment schemes have since the 1980s...

The Effect of pH on Slurry Erosion-Corrosion of Tungsten Carbide Overlays Alloyed with Ru

Science.gov (United States)

Nelwalani, Ndivhuwo B.; van der Merwe, Josias W.

2018-02-01

The aim of the study was to determine the effect of Ru additions to WC-Fe overlays when exposed to low pH slurry erosion conditions. These overlays were applied through Plasma Transferred Arc, and the original bulk Ru powder concentrations varied from 0.5 to 5 wt.%. A slurry jet impingement erosion-corrosion test rig was used to evaluate wear, and electrochemical measurements were performed to characterize the corrosion properties. The slurry mixtures contained silica sand and synthetic mine water. The pH was varied between 3 and 6.5 for the slurry erosion tests and lowered further for the corrosion characterization. Samples were examined optically and with a scanning electron microscope using energy-dispersive x-ray spectroscopy. X-ray diffraction analysis was used to determine the phases present. For the slurry erosion-corrosion results at the pH of 6.5, addition of Ru did not show a decrease in erosion-corrosion rates. However, when the pH was decreased to 3, by the addition of HCl, Ru improved the resistance. From the electrochemistry, it was also clear that Ru additions improved the corrosion resistance, but more than 1 wt.% Ru was required. At very low pH levels, the presence of Ru was not able to prevent corrosion.

Influence of sand base preparation on properties of chromite moulding sands with sodium silicate hardened with selected methods

Directory of Open Access Journals (Sweden)

Stachowicz M.

2017-03-01

Full Text Available The paper presents a research on the relation between thermal preparation of chromite sand base of moulding sands containing sodium silicate, hardened with selected physical and chemical methods, and structure of the created bonding bridges. Test specimens were prepared of chromite sand - fresh or baked at 950°C for 10 or 24 hours - mixed with 0.5 wt.% of the selected non-modified inorganic binder and, after forming, were hardened with CO2 or liquid esters, dried traditionally or heated with microwaves at 2.45 GHz. It was shown on the grounds of SEM observations that the time of baking the base sand and the hardening method significantly affect structure of the bonding bridges and are correlated with mechanical properties of the moulding sands. It was found that hardening chromite-based moulding mixtures with physical methods is much more favourable than hardening with chemical methods, guaranteeing also more than ten times higher mechanical properties.

Evaluation of air jet erosion profiles in metal mesh supported SCR plate catalyst based on glass fiber concentrations

Science.gov (United States)

Rajath, S.; Nandakishora, Y.; Siddaraju, C.; Roy, Sukumar

2018-04-01

This paper explains the evaluation of erosion profiles in metal mesh supported SCR plate catalyst structures in which the glass fibers concentration in the catalyst material is considered as prime factor for erosion resistance and mechanical strength. The samples are prepared and tested at the specified and constant conditions like velocity as 30m/s, sand flow rate as 2g/min, average particle diameter 300 µm and all these samples were tested at different angles at impact preferably 15°,30°,45°,60°,75°,and 90° as per ASTM G76 standards. Say, if 5% glass fibers are present in catalyst material, then erosion resistance increases, but the density of glass fibers is very less because each glass fiber is approximately 20 microns in diameter and weight of individual is negligible. The composition in which 2% fiber is present has slightly higher erosion comparatively, but 3% glass fibers or more foreign inclusion like excessive binders can be eliminated that contributes much for the conversion of NOx. So 2% -3% glass fibers are preferred and optimized based on NOx conversion and erosion resistance property.

Automated lake-wide erosion predictions and economic damage calculations upstream of the Moses-Saunders power dam

International Nuclear Information System (INIS)

Zuzek, P.; Baird, W.F.; International Joint Commission, Ottawa, ON

2008-01-01

This presentation discussed an automated flood and erosion prediction system designed for the upstream sections of the Moses-Saunders power dam. The system included a wave prediction component along with 3-D maps, hourly run-ups, geographic information system (GIS) tools and a hazard analysis tool. Parcel, reach, township, and county databases were used to populate the system. The prediction system was used to develop detailed study sites of shore units in the study area. Shoreline classes included sand and cohesive buffs, low banks, coarse beaches, and cobble or boulder lags. Time series plots for Lake Ontario water and wave levels were presented. Great Lakes ice cover data were also included in the system as well as erosion predictions from 1961 to 1995. The system was also used to develop bluff recession equations and cumulative recession analyses for different regulation plans. Cumulative bluff recession and protection requirements were outlined. Screenshots of the flood and erosion prediction system interface were also included. tabs., figs

A hierachical method for soil erosion assessment and spatial risk modelling

NARCIS (Netherlands)

Okoth, P.F.

2003-01-01

  Though a lot has been done and achieved in erosion research and control in Kenya, most of the erosion research methods have in the past put emphasis more on quantifying soil loss or measuring soil erosion, rather than pinpointing to

Environmental survey - tar sands in situ processing research program (Vernal, Uintah County, Utah). [Reverse-forward combustion; steam injection

Energy Technology Data Exchange (ETDEWEB)

Skinner, Q.

1980-03-01

Research will be done on the reverse-forward combustion and steam injection for the in-situ recovery of oil from tar sands. This environmental survey will serve as a guideline for the consideration of environmental consequences of such research. It covers the construction phase, operational phase, description of the environment, potential impacts and mitigations, coordination, and alternatives. (DLC)

Infra Red Aerial Photograph Interpretation for Soil Erosion at Wuryantoro, Wonogiri

Directory of Open Access Journals (Sweden)

S Suharjo

2016-07-01

Full Text Available Collecting data of soil erosion hazard terrestrially needs much time, high cost, and large energy. Therefore it is needed appropriate technology in addition to terrestrially decreasing necessity of time, cost and energy. Aerial photograph is picture of earth surface, which shape and place similar to condition on earth surface. Using aerial photograph in this research is expected to be able to take account for erosion factors. This research is conducted in Kecamatan Wuryantoro Kabupaten Wonogiri. Research method that used is aerial photograph interpretation with land unit approach. Amounts of soil lost are approached with USLE formula. Aerial photograph that used in this research is aerial photograph coloured infrared with 1:10.000 in scale and 1991 in year of taking photography. The result shows that using aerial photograph is very useful in supporting soil erosion rate calculation. Erosion rate at research area is 0.0968 ton/ha/year to 100.4344 ton/ha/year. This number is included in class of light erosion hazard (

Recent advances in research on the aeolian geomorphology of China's Kumtagh Sand Sea

Science.gov (United States)

Dong, Z.; Lv, P.

2014-02-01

The Kumtagh Sand Sea in the hyper-arid region of northwestern China remained largely unexplored until the last decade. It deserves study due to its significance in understanding the evolution of the arid environments in northwestern China, and even central Asia. Aeolian geomorphology in the sand sea has received unprecedented study in the last decade. Encouraging advances have been made in types of aeolian landforms, geological outlines, wind systems, the formation of aeolian landforms, several unique aeolian landforms, aeolian geomorphic regionalization, aeolian geomorphological heritages and tourism development, and aeolian sand hazards and their control. These advances expand our knowledge of aeolian geomorphology.

Beach Sand Analysis for Indicators of Microbial Contamination

Science.gov (United States)

Traditional beach monitoring has focused on water quality, with little attention paid to health risks associated with beach sand. Recent research has reported that fecal indicator bacteria, as well as human pathogens can be found in beach sand and may constitute a risk to human h...

Hydrology and soil erosion

Science.gov (United States)

Leonard J. Lane; Mary R. Kidwell

2003-01-01

We review research on surface water hydrology and soil erosion at the Santa Rita Experimental Range (SRER). Almost all of the research was associated with eight small experimental watersheds established from 1974 to 1975 and operated until the present. Analysis of climatic features of the SRER supports extending research findings from the SRER to broad areas of the...

Reclaimability of the spent sand mixture – sand with bentonite – sand with furfuryl resin

Directory of Open Access Journals (Sweden)

J. Dańko

2011-04-01

Full Text Available Introduction of new binding materials and new technologies of their hardening in casting moulds and cores production requires theapplication of reclamation methods adequate to their properties as well as special devices realizing tasks. The spent sands circulationsystem containing the same kind of moulding and core sands is optimal from the point of view of the expected reclamation results.However, in the face of a significant variability of applied technologies and related to them various reclamation methods, the need - of theobtained reclamation products assessment on the grounds of systematic criteria and uniform bases – arises, with a tendency of indicatingwhich criteria are the most important for the given sand system. The reclaimability results of the mixture of the spent moulding sand withGeko S bentonite and the spent core sand with the Kaltharz 404U resin hardened by acidic hardener 100 T3, are presented in the paper.Investigations were performed with regard to the estimation of an influence of core sands additions (10 –25% on the reclaimed materialquality. Dusts and clay content in the reclaim, its chemical reaction (pH and ignition loss were estimated. The verification of the reclaiminstrumental assessment was performed on the basis of the technological properties estimation of moulding sand with bentonite, where the reclaimed material was used as a matrix.

Texture and composition of the Rosa Marina beach sands (Adriatic coast, southern Italy: a sedimentological/ecological approach

Directory of Open Access Journals (Sweden)

Moretti Massimo

2016-06-01

Full Text Available Beach sands from the Rosa Marina locality (Adriatic coast, southern Italy were analysed mainly microscopically in order to trace the source areas of their lithoclastic and bioclastic components. The main cropping out sedimentary units were also studied with the objective to identify the potential source areas of lithoclasts. This allowed to establish how the various rock units contribute to the formation of beach sands. The analysis of the bioclastic components allows to estimate the actual role of organisms regarding the supply of this material to the beach. Identification of taxa that are present in the beach sands as shell fragments or other remains was carried out at the genus or family level. Ecological investigation of the same beach and the recognition of sub-environments (mainly distinguished on the basis of the nature of the substrate and of the water depth was the key topic that allowed to establish the actual source areas of bioclasts in the Rosa Marina beach sands. The sedimentological analysis (including a physical study of the beach and the calculation of some statistical parameters concerning the grain-size curves shows that the Rosa Marina beach is nowadays subject to erosion.

CFD simulation and experimental analysis of erosion in a slurry tank test rig

Directory of Open Access Journals (Sweden)

Bart Hans-Jörg

2013-04-01

Full Text Available Erosion occurring in equipment dealing with liquid-solid mixtures such as pipeline parts, slurry pumps, liquid-solid stirred reactors and slurry mixers in various industrial applications results in operational failure and economic costs. A slurry erosion tank test rig is designed and was built to investigate the erosion rates of materials and the influencing parameters such as flow velocity and turbulence, flow angle, solid particle concentration, particles size distribution, hardness and target material properties on the material loss and erosion profiles. In the present study, a computational fluid dynamics (CFD tool is used to simulate the erosion rate of sample plates in the liquid-solid slurry mixture in a cylindrical tank. The predictions were made in a steady state and also transient manner, applying the flow at the room temperature and using water and sand as liquid and solid phases, respectively. The multiple reference frame method (MRF is applied to simulate the flow behavior and liquid-solid interactions in the slurry tank test rig. The MRF method is used since it is less demanding than sliding mesh method (SM and gives satisfactory results. The computational domain is divided into three regions: a rotational or MRF zone containing the mixer, a rotational zone (MRF containing the erosion plates and a static zone (outer liquid zone. It is observed that changing the MRF zone diameter and height causes a very low impact on the results. The simulated results were obtained for two kinds of hard metals namely stainless steel and ST-50 under some various operating conditions and are found in good agreement with the experimental results.

Application of NAA in study of rill erosion process

International Nuclear Information System (INIS)

Li Mian; Li Zhanbin; Ding Wenfeng

2003-01-01

Based on the principle and method of rare earth elements (REE) tracer and NAA for the study of soil erosion, the changeable process of rill erosion on loess sloping surface was researched in runoff scouring experiments. The results showed that the REE tracer and NAA method can be used not only quantitatively to determine soil erosion amounts on different slope sections, but also to reveal the changeable trend of relative erosion amounts. The relative errors are mostly less than ±20% for the tracing elements, which is considered satisfactory in the soil erosion studies

Robotic weld overlay coatings for erosion control

Science.gov (United States)

The erosion of materials by the impact of solid particles has received increasing attention during the past twenty years. Recently, research has been initiated with the event of advanced coal conversion processes in which erosion plays an important role. The resulting damage, termed Solid Particle Erosion (SPE), is of concern primarily because of the significantly increased operating costs which result in material failures. Reduced power plant efficiency due to solid particle erosion of boiler tubes and waterfalls has led to various methods to combat SPE. One method is to apply coatings to the components subjected to erosive environments. Protective weld overlay coatings are particularly advantageous in terms of coating quality. The weld overlay coatings are essentially immune to spallation due to a strong metallurgical bond with the substrate material. By using powder mixtures, multiple alloys can be mixed in order to achieve the best performance in an erosive environment. However, a review of the literature revealed a lack of information on weld overlay coating performance in erosive environments which makes the selection of weld overlay alloys a difficult task. The objective of this project is to determine the effects of weld overlay coating composition and microstructure on erosion resistance. These results will lead to a better understanding of erosion mitigation in CFB's.

Hydrology in a Mediterranean mountain environment, the Vallcebre Research basins (North Eastern Spain). IV. Testing hydrological and erosion models

International Nuclear Information System (INIS)

Gallart, F.; Latron, J.; Llorens, P.; Martinez-Carreras, N.

2009-01-01

Three modelling exercises were carried out in the Vallcebre research basins in order to both improve the understanding of the hydrological processes and test the adequate of some models in such Mediterranean mountain conditions. These exercises consisted of i) the analysis of the hydrological role of the agricultural terraces using the TOPMODEL topographic index, ii) the parametrisation of TOPMODEL using internal basin information, and iii) a test of the erosion model KINEROS2 for simulating badlands erosion. (Author) 13 refs.

Quality stabilisation of synthetic sand containing bentonite in process lines

OpenAIRE

A. Fedoryszyn

2010-01-01

Stabilisation of sand quality requires the monitoring and control of sand moisture contents and its other parameters at each stage of sandprocessing, i.e. during the preparation of return sand mix and rebonding processes. Stabilisation of sand quality necessitates the use of reliable control equipment and evaluation procedures. This study outlines the scope and results of research work aimed to improve the control equipment to enhance the performance of turbine mixers. The paper reviews the m...

Heavy mineral concentration from oil sand tailings

Energy Technology Data Exchange (ETDEWEB)

Chachula, F.; Erasmus, N. [Titanium Corp. Inc., Regina, SK (Canada)

2008-07-01

This presentation described a unique technique to recover heavy minerals contained in the froth treatment tailings produced by oil sand mining extraction operations in Fort McMurray, Alberta. In an effort to process waste material into valuable products, Titanium Corporation is developing technology to recover heavy minerals, primarily zircon, and a portion of bitumen contained in the final stage of bitumen processing. The process technology is being developed to apply to all mined oil sands operations in the Fort McMurray region. In 2004, Titanium Corporation commissioned a pilot research facility at the Saskatchewan Research Council to test dry oil sands tailings. In 2005, a bulk sampling pilot plant was connected to the fresh oil sands tailings pipeline on-site in Fort McMurray, where washed sands containing heavy minerals were processed at a pilot facility. The mineral content in both deposited tailings and fresh pipeline tailings was assessed. Analysis of fresh tailings on a daily basis identified a constant proportion of zircon and higher levels of associated bitumen compared with the material in the deposited tailings. The process flow sheet design was then modified to remove bitumen from the heavy minerals and concentrate the minerals. A newly modified flotation process was shown to be a viable processing route to recover the heavy minerals from froth treatment tailings. 8 refs., 9 tabs., 12 figs.

TILLAGE EROSION: THE PRINCIPLES, CONTROLLING FACTORS AND MAIN IMPLICATIONS FOR FUTURE RESEARCH

Directory of Open Access Journals (Sweden)

Agnieszka Wysocka-Czubaszek

2014-10-01

Full Text Available Tillage erosion is one of the major contributors to landscape evolution in hummocky agricultural landscapes. This paper summarizes the available data describing tillage erosion caused by hand-held or other simple tillage implements as well as tools used in typical conventional agriculture in Europe and North America. Variations in equipment, tillage speed, depth and direction result in a wide range of soil translocation rates observed all over the world. The variety of tracers both physical and chemical gives a challenge to introduce the reliable model predicting tillage erosion, considering the number and type of tillage operation in the whole tillage sequence.

Design of dry sand soil stratified sampler

Science.gov (United States)

Li, Erkang; Chen, Wei; Feng, Xiao; Liao, Hongbo; Liang, Xiaodong

2018-04-01

This paper presents a design of a stratified sampler for dry sand soil, which can be used for stratified sampling of loose sand under certain conditions. Our group designed the mechanical structure of a portable, single - person, dry sandy soil stratified sampler. We have set up a mathematical model for the sampler. It lays the foundation for further development of design research.

Erosion control works and the intensity of soil erosion in the upper part of the river Toplica drainage basin

International Nuclear Information System (INIS)

Kostadinov, S; Dragovic, N; Zlatic, M; Todosijevic, M

2008-01-01

Aiming at the protection of the future storage 'Selova' against erosion and sediment, and also to protect the settlements and roads in the drainage basin against torrential floods, erosion control works in the upper part of the river Toplica basin, upstream of the storage 'Selova', started in 1947. The works included building-technical works (check dams) and biological works (afforestation and grassing of bare lands and other erosion risk areas). Within the period 1947-2006, the following erosion control works were executed: afforestation of bare lands on the slopes 2,257.00 ha, grassing of bare lands 1,520.00 ha, and altogether 54 dams were constructed in the river Toplica tributaries. This caused the decrease of sediment transport in the main flow of the river Toplica. This paper, based on the field research conducted in two time periods: 1988 and in the period 2004-2007, presents the state of erosion in the basin before erosion control works; type and scope of erosion control works and their effect on the intensity of erosion in the river Toplica basin upstream of the future storage 'Selova'.

Soil erodibility for water erosion: A perspective and Chinese experiences

Science.gov (United States)

Wang, Bin; Zheng, Fenli; Römkens, Mathias J. M.; Darboux, Frédéric

2013-04-01

Knowledge of soil erodibility is an essential requirement for erosion prediction, conservation planning, and the assessment of sediment related environmental effects of watershed agricultural practices. This paper reviews the status of soil erodibility evaluations and determinations based on 80 years of upland area erosion research mainly in China and the USA. The review synthesizes the general research progress made by discussing the basic concepts of erodibility and its evaluation, determination, and prediction as well as knowledge of its spatio-temporal variations. The authors found that soil erodibility is often inappropriately or inaccurately applied in describing soil loss caused by different soil erosion component processes and mechanisms. Soil erodibility indicators were related to intrinsic soil properties and exogenic erosional forces, measurements, and calculations. The present review describes major needs including: (1) improved definition of erodibility, (2) modified erodibility determinations in erosion models, especially for specific geographical locations and in the context of different erosion sub-processes, (3) advanced methodologies for quantifying erodibilities of different soil erosion sub-processes, and (4) a better understanding of the mechanism that causes temporal variations in soil erodibility. The review also provides a more rational basis for future research on soil erodibility and supports predictive modeling of soil erosion processes and the development of improved conservation practices.

A terminological matter: paragenesis, antigravitative erosion or antigravitational erosion ?

Directory of Open Access Journals (Sweden)

Pasini G.

2009-07-01

Full Text Available In the speleological literature three terms are utilized to designate the “ascending erosion”: paragenesis (= paragénésis, coined in1968, antigravitative erosion (= erosione antigravitativa, coined in 1966 and antigravitational erosion (wrong English translation ofthe Italian term erosione antigravitativa, utilized later on. The term paragenesis should be abandoned because of the priority of theterm erosione antigravitativa - on the ground of the “law of priority” – and because of its ambiguous etimology. On the other hand,the term antigravitational erosion should be forsaken in favour of the term antigravitative erosion, given the meaning that the termsgravitation and gravity have in Physics. Therefore, to designate the phenomenon of the “ascending erosion” there would be nothingleft but the term antigravitative erosion.The antigravitative erosion process and its recognizability are illustrated.Examples of caves with evident antigravitative erosion phenomena, developed in different karstifiable rocks and in several partsof the world, are given.It is recalled that the antigravitative erosion is a phenomenon well-known since 1942 and widely proven and supported, and that it isrelatively easy – in many cases - to recognize the antigravitative origin of karstic passages.It is stressed that the antigravitative erosion is an important phenomenon, exclusive of the karstic caves and unique in nature.

Changes in wind erosion over a 25-year restoration chronosequence on the south edge of the Tengger Desert, China: implications for preventing desertification.

Science.gov (United States)

Ma, Quanlin; Fehmi, Jeffrey S; Zhang, Dekui; Fan, Baoli; Chen, Fang

2017-08-23

Wind erosion is a primary cause of desertification as well as being a serious ecological problem in arid and semi-arid areas across the world. To determine mechanisms for restoring desertified lands, an unrestored shifting sand dune and three formerly shifting sand dunes (desertified lands) that had been enclosed and afforested for 5, 15, and 25 years were selected for evaluation on the south edge of the Tengger Desert, China. Based on sampling heights between 0.2 and 3 m, the critical threshold average wind speed was 6.5 m s -1 at 2 m where the sand transport rate was reduced from 285.9 kg m -2  h -1 on the unrestored dunes to 9.1 and 1.8 kg m -2  h -1 on the sites afforested and enclosed for 5 and 15 years, respectively. The percentage of wind eroded area was reduced from 99.9% on the unrestored dune to 94.5, 9.0, and 0.5% on the sites afforested and enclosed for 5, 15, and 25 years, respectively. Wind erosion was effectively reduced after 15 years. Although there were different driving factors for wind erosion mitigation on the different restoration stages, an increase in the vegetation cover, surface roughness, soil shear strength, soil clay content, organic matter, and reduction in the near-surface wind speed were the primary variables associated with the restoration chronosequence. We conclude that reducing the wind speed and developing a biological crust through vegetation restoration were the critical components for restoration of desertified land.

Modeling the fluid/soil interface erosion in the Hole Erosion Test

Directory of Open Access Journals (Sweden)

Kissi B.

2012-07-01

Full Text Available Soil erosion is a complex phenomenon which yields at its final stage to insidious fluid leakages under the hydraulic infrastructures known as piping and which are the main cause of their rupture. The Hole Erosion Test is commonly used to quantify the rate of piping erosion. In this work, The Hole Erosion Test is modelled by using Fluent software package. The aim is to predict the erosion rate of soil during the hole erosion test. The renormalization group theory – based k–ε turbulence model equations are used. This modelling makes it possible describing the effect of the clay concentration in flowing water on erosion. Unlike the usual one dimensional models, the proposed modelling shows that erosion is not uniform erosion along the hole length. In particular, the concentration of clay is found to increase noticeably the erosion rate.

Determination of 7BE in soil sample by gamma spectrometry for erosion researchs

International Nuclear Information System (INIS)

Esquivel, Alexander D.; Kastner, Geraldo F.; Amaral, Angela M.; Monteiro, Roberto Pellacani G.; Moreira, Rubens M.

2015-01-01

Cosmogenic 7 Be is a natural radiotracer produced in the stratosphere and troposphere and reached to the Earth surface via wet and dry fallout and hence its measurement for research of erosion in soils is very significant. The 7 Be radio analyse based on gamma spectrometry technique has been a routine methodology for decades and although is the reference procedure is not free of analytical interference. 7 Be is a β-γ emitting radionuclide (Eγ = 477.59 keV, T½ = 53.12d) and depending on the chemical profile of the soil its determination is susceptible to 228 Ac (E γ = 478.40 keV, T½ = 6.15h) interference. The aim of this work was to establish an analytical protocol for the 7 Be determination in soil samples from Juatuba-Mg region in different sampling periods of dry and rainy seasons for erosion studies and to establish some methodologies for evaluating and correcting the interference level of 228 Ac in the 7 Be activity measurements by gamma spectrometry. (author)

Eastern Scheldt Sand, Baskarp Sand No. 15

DEFF Research Database (Denmark)

Andersen, A. T; Madsen, E. B.; Schaarup-Jensen, A. L.

The present data report contains data from 13 drained triaxial tests, performed on two different sand types in the Soil Mechanics Laboratory at Aalborg University in March, 1997. Two tests have been performed on Baskarp Sand No. 15, which has already ken extensively tested in the Soil Mechanics...... Laboratory. The remaining 11 triaxial tests have ben performed on Eastern Scheldt Sand, which is a material not yet investigated at the Soil Mechanics Laboratory. In the first pari of this data report, the characteristics of the two sand types in question will be presented. Next, a description...... will described. In this connection, the procedure for preparation of the soil specimens will be presented, and the actual performance of the tests will be briefly outlined. Finally, the procedure for processing of the measurements from the laboratory in order to obtain usable data will be described. The final...

Matahina Dam : lessons learned from an earthquake-related internal erosion incident at the Matahina Dam, New Zealand

Energy Technology Data Exchange (ETDEWEB)

Gillon, M. [Damwatch Services Ltd., Wellington (New Zealand)

2009-07-01

This case history discussed internal erosion damage and crest subsidence caused by an earthquake at the Matahina Dam in New Zealand. The study showed that cracking and internal erosion was initiated during the 1967 reservoir filling operation. Located in an area of active volcanism and faulting, the dam is located on a river with extensive erosion through an ignimbrite flow. The dam's core is founded on compact Tertiary age sediments overlain by sand and gravel deposits beneath the shoulders of the dam. The earthquake caused a rupture along an unidentified fault trace 12 km from the dam. The horizontal base acceleration recorded at the dam was 3.25 m/s. Transverse cracking was observed at each abutment, and deformations were observed in the rockfill. An investigation program was conducted to determine the dam's integrity. Piezometer measurements showed widespread fluctuations. It was concluded that the lack of an effective filter was a significant design omission. 12 refs., 12 figs.

Erosion Prediction Analysis and Landuse Planning in Gunggung Watershed, Bali, Indonesia

Science.gov (United States)

Trigunasih, N. M.; Kusmawati, T.; Yuli Lestari, N. W.

2018-02-01

The purpose of this research is to predict the erosion that occurs in Gunggung watershed and sustainable landuse management plan. This research used the USLE (Universal Soil Loss Equation) methodology. The method used observation / field survey and soil analysis at the Soil Laboratory of Faculty of Agriculture, Udayana University. This research is divided into 5 stages, (1) land unit determination, (2) Field observation and soil sampling, (3) Laboratory analysis and data collection, (4) Prediction of erosion using USLE (Universal Soil Loss Equation) method, (5) The permissible erosion determination (EDP) then (6) determines the level of erosion hazard based on the depth of the soil, as well as the soil conservation plan if the erosion is greater than the allowed erosion, and (7) determining landuse management plan for sustainable agriculture. Erosion which value is smaller than soil loss tolerance can be exploited in a sustainable manner, while erosion exceeds allowable erosion will be conservation measures. Conservation action is the improvement of vegetation and land management. Land management like improvements the terrace, addition of organic matter, increase plant density, planting ground cover and planting layered header system will increase the land capability classes. Land use recommended after management is mixed plantation high density with forest plants, mix plantation high density with patio bench construction, seasonal cultivation and perennial crops, cultivation of perennial crops and cultivation of seasonal crops.

Programs to obtain vertical heights from mean sea level and for computing volume of sand/mineral along beaches: A case study with Kalbadevi beach profiling data and results

Digital Repository Service at National Institute of Oceanography (India)

Ganesan, P.

Two programs have been developed to process profile data, for obtaining vertical heights with respect to mean sea level (M.S.L.) and for computation of volume of heavy mineral / sand accumulation or erosion along the beaches. The final output...

On researching erosion-corrosion wear in pipelines: the rate and residual lifetime estimation

International Nuclear Information System (INIS)

Baranenko, V.I.; Yanchenko, Yu.A.; Gulina, O.M.; Dokukin, D.A.

2010-01-01

To base the normative document on calculation of pipelines erosive-corrosive wear (ECW) rate and residual lifetime this research of ECW regularities for pearlitic steel NPP pipelines was performed. The estimates of control data treatment statistical procedures efficiency were presented. The influence of the scheme of piping control on the ECW rate and residual lifetime estimation results was demonstrated. The simplified scheme is valid only in case of complete information. It's usage under data uncertainties leads to essential residual lifetime overstating [ru

The stable stiffness triangle - drained sand during deformation cycles

DEFF Research Database (Denmark)

Sabaliauskas, Tomas; Ibsen, Lars Bo

2017-01-01

Cyclic, drained sand stiffness was observed using the Danish triaxial appa- ratus. New, deformation dependant soil property (the stable stiffness triangle) was detected. Using the the stable stiffness triangle, secant stiffness of drained sand was plausible to predict (and control) even during ir...... findings can find application in off-shore, seismic and other engi- neering practice, or inspire new branches of research and modelling wherever dynamic, cyclic or transient loaded sand is encountered....

The Monitoring Erosion of Agricultural Land and spatial database of erosion events

Science.gov (United States)

Kapicka, Jiri; Zizala, Daniel

2013-04-01

In 2011 originated in The Czech Republic The Monitoring Erosion of Agricultural Land as joint project of State Land Office (SLO) and Research Institute for Soil and Water Conservation (RISWC). The aim of the project is collecting and record keeping information about erosion events on agricultural land and their evaluation. The main idea is a creation of a spatial database that will be source of data and information for evaluation and modeling erosion process, for proposal of preventive measures and measures to reduce negative impacts of erosion events. A subject of monitoring is the manifestations of water erosion, wind erosion and slope deformation in which cause damaged agriculture land. A website, available on http://me.vumop.cz, is used as a tool for keeping and browsing information about monitored events. SLO employees carry out record keeping. RISWC is specialist institute in the Monitoring Erosion of Agricultural Land that performs keeping the spatial database, running the website, managing the record keeping of events, analysis the cause of origins events and statistical evaluations of keeping events and proposed measures. Records are inserted into the database using the user interface of the website which has map server as a component. Website is based on database technology PostgreSQL with superstructure PostGIS and MapServer UMN. Each record is in the database spatial localized by a drawing and it contains description information about character of event (data, situation description etc.) then there are recorded information about land cover and about grown crops. A part of database is photodocumentation which is taken in field reconnaissance which is performed within two days after notify of event. Another part of database are information about precipitations from accessible precipitation gauges. Website allows to do simple spatial analysis as are area calculation, slope calculation, percentage representation of GAEC etc.. Database structure was designed

Partitioning sediment flux by provenance and tracing erosion patterns in Taiwan

Science.gov (United States)

Resentini, Alberto; Goren, Liran; Castelltort, Sébastien; Garzanti, Eduardo

2017-07-01

We critically evaluate the potential and limitations of an alternative way to calculate erosion rates based on petrographic and mineralogical fingerprints of fluvial sediments coupled with gauged sediment fluxes. Our approach allows us to apportion sediment loads to different lithological units, and consequently to discriminate erosion rates in different tectonic domains within each catchment. Our provenance data on modern Taiwanese sands indicate focused erosion in the Backbone Range and Tananao Complex of the retrowedge. Lower rates are inferred for the northern part of the island characterized by tectonic extension and for the western foothills in the prowedge. The principal factor of uncertainty affecting our estimates is the inevitably inaccurate evaluation of total sediment load, because only the suspended flux was measured. Another is the assumption that suspended load and bed load are derived from the same sources in fixed proportions. Additional errors are caused by the insufficiently precise definition of lithologically similar compositional end-members and by the temporal variability of sediment composition at the outlet of each catchment related to the spatial variability of erosional processes and triggering agents such as earthquakes, typhoons, and landslides. To evaluate the robustness of our findings, we applied a morphometric technique based on the stream-power model. The results obtained are broadly consistent, with local discrepancies ascribed to poorly constrained assumptions and choices of scaling parameters. Our local erosion estimates are consistent with GPS uplift rates measured on a decadal timescale and generally higher than basin-wide results inferred from cosmogenic-nuclide and thermochronology data.

Recovery of native prairie after pipeline construction in the Sand Hills region of Saskatchewan

International Nuclear Information System (INIS)

Walker, D.; Kremer, L.; Marshall, W.

1996-01-01

Land reclamation measures taken after construction of a large diameter natural gas pipeline in the Great Sand Hills region of southwestern Saskatchewan were detailed. Mitigation measures included modified construction procedures to minimize the size of the disturbance, worker educational programs to sensitize them to the prevailing fragile environment, dormant season construction, efforts to salvage topsoil seedbank, fertilizer application, straw bale wind barriers, brush mulch wind barriers, surface manipulation with the Hodder Gouger, fencing-out cattle, and the application of a seed mixture of agronomic legumes and native grasses. Vegetation and soil erosion were monitored over a period of four years. After four years the canopy cover was 88 per cent native species. On low-lying, protected sites vegetation was stable enough to support cattle grazing. Exposed sites will not reach this level of vegetation stability for some years to come due soil erosion by wind

Erosion of surface and near surface disposal facilities

International Nuclear Information System (INIS)

1988-06-01

A literature search was undertaken to identify existing data and analytical procedures regarding the processes of gully erosion. The applicability of the available information to the problems of gully erosion potential at surface and near surface disposal sites is evaluated. It is concluded that the existing knowledge regarding gully erosion is insufficient to develop procedures to ensure the long-term stability of disposal sites. Recommendations for further research are presented. 46 refs

Oil sands supply outlook

International Nuclear Information System (INIS)

Dunbar, R.

2004-01-01

In March 2004, The Canadian Energy Research Institute released a report on the expected future supply from Alberta's oil sands. The report indicates that the future for the already well-established oil sands industry is promising, particularly given the outlook for oil prices. The challenges facing the industry include higher industry supply costs and the need for innovative commercial and technological solutions to address the risks of irregularities and changes in crude oil prices. In 2003, the industry produced 874 thousand barrels per day of synthetic crude oil and unprocessed crude bitumen. This represents 35 per cent of Canada's total oil production. Current production capacity has increased to 1.0 million barrels per day (mbpd) due to new projects. This number may increase to 3.5 mbpd by 2017. Some new projects may be deferred due to the higher raw bitumen and synthetic crude oil supply costs. This presentation provided supply costs for a range of oil sands recovery technologies and production projections under various business scenarios. tabs., figs

Numerical modelling of concentrated leak erosion during Hole Erosion Tests

OpenAIRE

Mercier, F.; Bonelli, S.; Golay, F.; Anselmet, F.; Philippe, P.; Borghi, R.

2015-01-01

This study focuses on the numerical modelling of concentrated leak erosion of a cohesive soil by a turbulent flow in axisymmetrical geometry, with application to the Hole Erosion Test (HET). The numerical model is based on adaptive remeshing of the water/soil interface to ensure accurate description of the mechanical phenomena occurring near the soil/water interface. The erosion law governing the interface motion is based on two erosion parameters: the critical shear stress and the erosion co...

Modeling sheet-flow sand transport under progressive surface waves

NARCIS (Netherlands)

Kranenburg, Wouter

2013-01-01

In the near-shore zone, energetic sea waves generate sheet-flow sand transport. In present day coastal models, wave-induced sheet-flow sand transport rates are usually predicted with semi-empirical transport formulas, based on extensive research on this phenomenon in oscillatory flow tunnels.

Influence factors of sand-bentonite mixtures on hydraulic conductivity

International Nuclear Information System (INIS)

Chen Yonggui; Ye Weimin; Chen Bao; Wan Min; Wang Qiong

2008-01-01

Buffer material is a very important part of the engineering barrier for geological disposal of high-level radioactive nuclear waste. Compacted bentonite is attracting greater attention as buffer and backfill material because it offer impermeability and swelling properties, but the pure compacted bentonite strength decreases with increasing hydration and these will reduce the buffer capability. To solve this problem, sand is often used to form compacted sand-bentonite mixtures (SBMs) providing high thermal conductivity, excellent compaction capacity, long-time stability, and low engineering cost. As to SBMs, hydraulic conductivity is a important index for evaluation barrier capability. Based on the review of research results, the factors affecting the hydraulic conductivity of SBMs were put forward including bentonite content, grain size distribution, moisture content, dry density, compacting method and energy, and bentonite type. The studies show that the hydraulic conductivity of SBMs is controlled by the hydraulic conductivity of the bentonite, it also decreases as dry density and bentonite content increase, but when the bentonite content reach a critical point, the influence of increasing bentonite to decrease the hydraulic conductivity is limited. A fine and well-graded SBMs is likely to have a lower hydraulic conductivity than a coarse and poorly graded material. The internal erosion or erodibility based on the grain size distribution of the SBMs has a negative effect on the final hydraulic conductivity. The lowest hydraulic conductivity is gained when the mixtures are compacted close to optimum moisture content. Also, the mixtures compacted at moisture contents slightly above optimum values give lower hydraulic conductivity than when compacted at slightly under the optimum moisture content. Finally, discussion was brought to importance of compaction method, compacting energy, and bentonite type to the hydraulic conductivity of SBMs. (authors)

Methodology update for determination of the erosion coefficient(Z

Directory of Open Access Journals (Sweden)

Tošić Radislav

2012-01-01

Full Text Available The research and mapping the intensity of mechanical water erosion that have begun with the empirical methodology of S. Gavrilović during the mid-twentieth century last, by various intensity, until the present time. A many decades work on the research of these issues pointed to some shortcomings of the existing methodology, and thus the need for its innovation. In this sense, R. Lazarević made certain adjustments of the empirical methodology of S. Gavrilović by changing the tables for determination of the coefficients Φ, X and Y, that is, the tables for determining the mean erosion coefficient (Z. The main objective of this paper is to update the existing methodology for determining the erosion coefficient (Z with the empirical methodology of S. Gavrilović and amendments made by R. Lazarević (1985, but also with better adjustments to the information technologies and the needs of modern society. The proposed procedure, that is, the model to determine the erosion coefficient (Z in this paper is the result of ten years of scientific research and project work in mapping the intensity of mechanical water erosion and its modeling using various models of erosion in the Republic of Srpska and Serbia. By analyzing the correlation of results obtained by regression models and results obtained during the mapping of erosion on the territory of the Republic of Srpska, a high degree of correlation (R² = 0.9963 was established, which is essentially a good assessment of the proposed models.

Buffer erosion: An overview of concepts and potential safety consequences

International Nuclear Information System (INIS)

Apted, Michael J.; Arthur, Randy; Bennett, David; Savage, David; Saellfors, Goeran; Wennerstroem, Haakan

2010-11-01

In its safety analysis SR-Can, SKB reported preliminary results and conclusions on the mechanisms of bentonite colloid formation and stability, with a rough estimate of the consequences of loss of bentonite buffer by erosion. With the review of SR-Can the authorities (SKI and SSI) commented that erosion of the buffer had the greatest safety significance, that the understanding of the mechanisms of buffer erosion was inadequate, and that more work would be required to arrive at robust estimates of the extent and impacts of buffer erosion. After the SR-Can report, SKB started a two-year research project on buffer erosion. The results from this two-year project have been reported in several SKB technical reports. SSM started this project to build up its own competence in the related scientific areas by a preliminary evaluation of SKB's research results

Buffer erosion: An overview of concepts and potential safety consequences

Energy Technology Data Exchange (ETDEWEB)

Apted, Michael J.; Arthur, Randy (INTERA Incorporated, Denver, CO (United States)); Bennett, David (TerraSalus Limited, Rutland (United Kingdom)); Savage, David (Savage Earth Associates Limited, Bournemouth (United Kingdom)); Saellfors, Goeran (GeoForce AB, Billdal (Sweden)); Wennerstroem, Haakan (Dept. of Chemistry, Lund Univ., Lund (Sweden))

2010-11-15

In its safety analysis SR-Can, SKB reported preliminary results and conclusions on the mechanisms of bentonite colloid formation and stability, with a rough estimate of the consequences of loss of bentonite buffer by erosion. With the review of SR-Can the authorities (SKI and SSI) commented that erosion of the buffer had the greatest safety significance, that the understanding of the mechanisms of buffer erosion was inadequate, and that more work would be required to arrive at robust estimates of the extent and impacts of buffer erosion. After the SR-Can report, SKB started a two-year research project on buffer erosion. The results from this two-year project have been reported in several SKB technical reports. SSM started this project to build up its own competence in the related scientific areas by a preliminary evaluation of SKB's research results

Submarine sand ridges and sand waves in the eastern part of the China Sea

Science.gov (United States)

Wu, Ziyin; Li, Shoujun; Shang, Jihong; Zhou, Jieqiong; Zhao, Dineng; Liang, Yuyang

2016-04-01

Integrated with multi-beam and single-beam echo sounding data, as well as historical bathymetric data, submarine bathymetric maps of the eastern part of the China Sea, including the Bohai Sea, Huanghai Sea, and East China Sea, are constructed to systematically study submarine sand ridges and sand waves in the eastern part of the China Sea, combined with high-resolution seismic, sub-bottom profile and borehole data. Submarine sand ridges are extraordinarily developed in the eastern part of the China Sea, and 7 sand ridge areas can be divided from north to south, that is, the Laotieshan Channel sand ridge area in the Bohai Sea, the Korea Bay sand ridge area in the southern Huanghai Sea, the sand ridge area in the eastern Huanghai islands and the Huanghai Troughs, the Jianggang sand ridge area in the western Huanghai Sea, the sand ridge area in the East China Sea shelf, and the sand ridge and sand wave area in the Taiwan Strait and Taiwan Banks. The distribution area of the sand ridges and sand waves covers more than 450,000 km2, wherein ~10,000 km2 in the Bohai Bay, ~200,000 km2 in the Huanghai Sea, ~200,000 km2 in the East China Sea shelf, and ~40,000 km2 in the Taiwan Strait and Taiwan Banks, respectively. The great mass of sand ridges are distributed within water depth of 5-160 m, with a total length of over 160 km and a main width of 5-10 km. The inner structure of the sand ridges presents features of high-angle inclined beddings, with main lithology of sands, sand-mud alternations partly visible, and a small number of mud cores. Dating results indicate that the sand ridges in the eastern part of the China Sea are mainly developed in the Holocene. Sea-level variation dominates the sand ridge evolution in the eastern part of the China Sea since the LGM, and the sand ridges developed in the area of < 60m water depth are appeared in bad activity, meanwhile sand ridges with good activity are still developed in large scale.

Influence of Reclamation Process on the Ecological Quality of Reclaim Sand

Directory of Open Access Journals (Sweden)

Dereń M.

2017-12-01

Full Text Available In this article, there were presented results of research on influence of reclamation process on the ecological quality of reclaim sand with furan resin used in nonferrous foundry. The quality of reclaimed sand is mainly define by two group of chemical substances from elution of reclaimed sand: Dissolves Organic Carbon (DOC and Total Dissolves Solids (TDS. Reclaimed sand used in test was prepared in experimental thermal reclaimer and mechanical vibration reclaimer REGMAS installed in Faculty of Foundry Engineering at University Of Science and Technology in Krakow. The reference point is molding sand shaking out and crumble in jaw crusher. Test of elution was made in accredited laboratory in Center For Research and Environmental Control in Katowice up to the standard with Dissolves Organic Carbon (DOC - PN-EN 1484:1999; Total Dissolves Solids (TDS - PN-EN 15216:2010. The standard for elution test is PN-EN 12457- 4:2006. Except that we were made loss of ignition test, to check how many resin was rest on sand grains.

Non-cohesive silt turbidity current flow processes; insights from proximal sandy-silt and silty-sand turbidites, Fiordland, New Zealand

Science.gov (United States)

Strachan, Lorna J.; Bostock, Helen C.; Barnes, Philip M.; Neil, Helen L.; Gosling, Matthew

2016-08-01

Silt-rich turbidites are commonly interpreted as distal marine deposits. They are associated with interlaminated clay and silt deposition from the upper and rear portions of turbidity currents. Here, multibeam bathymetry and shallow sediment core data from the intra-slope Secretary Basin, Fiordland, New Zealand, located laminar) flows that have undergone a variety of up-dip flow transformations. Most flows were initially erosive followed by deposition of partitioned 2- or 3- phase mixed mode flows that include high-density transitional and laminar flows that can be fore- or after-runners to low-density turbulent flow sections. Turbulence is inferred to have been suppressed in high-density flows by increasing flow concentration of both sands and silts. The very fine and fine sand modal grain sizes of sandy-silt and silty-sand turbidites are significantly coarser than classical abyssal plain silt turbidites and are generally coarser than overbank silt turbidites. While the low percentage of clays within Secretary Basin sandy-silt and silty-sand turbidites represents a fundamental difference between these and other silt and mud turbidites, we suggest these beds represent a previously undescribed suite of proximal continental slope deposits.

The extraction of bitumen from western oil sands. Final report, July 1989--September 1993

Energy Technology Data Exchange (ETDEWEB)

Oblad, A.G.; Bunger, J.W.; Dahlstrom, D.A.; Deo, M.D.; Fletcher, J.V.; Hanson, F.V.; Miller, J.D.; Seader, J.D.

1994-03-01

Research and development of surface extraction and upgrading processes of western tar sands are described. Research areas included modified hot water, fluidized bed, and rotary kiln pyrolysis of tar sands for extraction of bitumen. Bitumen upgrading included solvent extraction of bitumen, and catalytic hydrotreating of bitumen. Characterization of Utah tar sand deposits is also included.

Differences and commonalities impregnation of dry and wet sand

Directory of Open Access Journals (Sweden)

Maujuda МUZAFFAROVA

2014-09-01

Full Text Available The article is devoted to research new methods of physic-chemical methods of preventing deflation to protect railways and highways from such phenomena as exogenous sand drifts. In particular, first studied the possibility of using binders in sand wet state. Results can significantly extend the scope of the method, and identified with particular impregnation maintaining stability requirements protective cover reduces both the concentration previously recommended binders, and their costs, thereby securing implementation in practice of shifting sands resource-saving technology.

A new turbulence-based model for sand transport

Science.gov (United States)

Mayaud, Jerome; Wiggs, Giles; Bailey, Richard

2016-04-01

Knowledge of the changing rate of sediment flux in space and time is essential for quantifying surface erosion and deposition in desert landscapes. While many aeolian studies have relied on time-averaged parameters such as wind velocity (U) and wind shear velocity (u*) to determine sediment flux, there is increasing evidence that high-frequency turbulence is an important driving force behind the entrainment and transport of sand. However, turbulence has yet to be incorporated into a functional sand transport model that can be used for predictive purposes. In this study we present a new transport model (the 'turbulence model') that accounts for high-frequency variations in the horizontal (u) and vertical (w) components of wind flow. The turbulence model is fitted to wind velocity and sediment transport data from a field experiment undertaken in Namibia's Skeleton Coast National Park, and its performance at three temporal resolutions (10 Hz, 1 Hz, 1 min) is compared to two existing models that rely on time-averaged wind velocity data (Radok, 1977; Dong et al., 2003). The validity of the three models is analysed under a variety of saltation conditions, using a 2-hour (1 Hz measurement resolution) dataset from the Skeleton Coast and a 5-hour (1 min measurement resolution) dataset from the southwestern Kalahari Desert. The turbulence model is shown to outperform the Radok and Dong models when predicting total saltation count over the three experimental periods. For all temporal resolutions presented in this study (10 Hz-10 min), the turbulence model predicted total saltation count to within at least 0.34%, whereas the Radok and Dong models over- or underestimated total count by up to 5.50% and 20.53% respectively. The strong performance of the turbulence model can be attributed to a lag in mass flux response built into its formulation, which can be adapted depending on the temporal resolution of investigation. This accounts for the inherent lag within the physical

Erosion reasons and rate on accumulative Polish dune coast caused by the January 2012 storm surge

Directory of Open Access Journals (Sweden)

Tomasz A. Łabuz

2014-03-01

Full Text Available The Polish coast is a non-tidal area; its shores are affected mainly by autumn-winter storm surges. Those of 6 and 14 January 2012 are representative of the forces driving the erosion of normally accumulative sections of coastal dunes, monitored by the author since 1997. The sea level maximum during these two storm surges reached 1.2 to 1.5 m amsl along the Polish coast. Land forms up to 3 m amsl were inundated. Beaches and low parts of the coast up to this height were rebuilt by sea waves attacking the coast for almost 12 days. Quantitative analyses of the morphological dynamics of the coastal dunes are presented for 57 profiles located along the coast. Only those accumulative sections of the Polish coast are analysed where sand accumulation did occur and led to new foredune development. The mean rate of dune erosion was 2.5 m3 per square metre with an average toe retreat of 1.4 m. Erosion understood as dune retreat was greater when a beach was lower (correlation coefficient 0.8. Dune erosion did not occur on coasts with beaches higher than 3.2 m or on lower ones covered by embryo dunes.

Coupling a basin erosion and river sediment transport model into a large scale hydrological model: an application in the Amazon basin

Science.gov (United States)

Buarque, D. C.; Collischonn, W.; Paiva, R. C. D.

2012-04-01

This study presents the first application and preliminary results of the large scale hydrodynamic/hydrological model MGB-IPH with a new module to predict the spatial distribution of the basin erosion and river sediment transport in a daily time step. The MGB-IPH is a large-scale, distributed and process based hydrological model that uses a catchment based discretization and the Hydrological Response Units (HRU) approach. It uses physical based equations to simulate the hydrological processes, such as the Penman Monteith model for evapotranspiration, and uses the Muskingum Cunge approach and a full 1D hydrodynamic model for river routing; including backwater effects and seasonal flooding. The sediment module of the MGB-IPH model is divided into two components: 1) prediction of erosion over the basin and sediment yield to river network; 2) sediment transport along the river channels. Both MGB-IPH and the sediment module use GIS tools to display relevant maps and to extract parameters from SRTM DEM (a 15" resolution was adopted). Using the catchment discretization the sediment module applies the Modified Universal Soil Loss Equation to predict soil loss from each HRU considering three sediment classes defined according to the soil texture: sand, silt and clay. The effects of topography on soil erosion are estimated by a two-dimensional slope length (LS) factor which using the contributing area approach and a local slope steepness (S), both estimated for each DEM pixel using GIS algorithms. The amount of sediment releasing to the catchment river reach in each day is calculated using a linear reservoir. Once the sediment reaches the river they are transported into the river channel using an advection equation for silt and clay and a sediment continuity equation for sand. A sediment balance based on the Yang sediment transport capacity, allowing to compute the amount of erosion and deposition along the rivers, is performed for sand particles as bed load, whilst no

Beach erosion and nest site selection by the leatherback sea turtle Dermochelys coriacea (Testudines: Dermochelyidae and implications for management practices at Playa Gandoca, Costa Rica

Directory of Open Access Journals (Sweden)

Matthew J Spanier

2010-12-01

Full Text Available Leatherback sea turtles (Dermochelys coriacea nest on dynamic, erosion-prone beaches. Erosive processes and resulting nest loss have long been presumed to be a hindrance to clutch survival. In order to better understand how leatherbacks cope with unstable nesting beaches, I investigated the role of beach erosion in leatherback nest site selection at Playa Gandoca, Costa Rica. I also examined the potential effect of nest relocation, a conservation strategy in place at Playa Gandoca to prevent nest loss to erosion, on the temperature of incubating clutches. I monitored changes in beach structure as a result of erosion at natural nest sites during the time the nest was laid, as well as in subsequent weeks. To investigate slope as a cue for nest site selection, I measured the slope of the beach where turtles ascended from the sea to nest, as well as the slopes at other random locations on the beach for comparison. I examined temperature differences between natural and relocated nest sites with thermocouples placed in the sand at depths typical of leatherback nests. Nests were distributed non-randomly in a clumped distribution along the length of the beach and laid at locations that were not undergoing erosion. The slope at nest sites was significantly different than at randomly chosen locations on the beach. The sand temperature at nest depths was significantly warmer at natural nest sites than at locations of relocated nests. The findings of this study suggest leatherbacks actively select nest sites that are not undergoing erosive processes, with slope potentially being used as a cue for site selection. The relocation of nests appears to be inadvertently cooling the nest environment. Due to the fact that leatherback clutches undergo temperaturedependent sex determination, the relocation of nests may be producing an unnatural male biasing of hatchlings. The results of this study suggest that the necessity of relocation practices, largely in place to

Offshore Sand Resource Needs, Data Availability and Revaluation, and Beach Nourishment Projects in North Carolina

Science.gov (United States)

Conery, I.; Walsh, J. P.

2016-12-01

Storms and sea-level rise continue to impact the dynamic coastlines of North Carolina. Since the coastal region is economically critical to the state and yields numerous ecosystem services, many towns have planned beach nourishment projects. However, offshore sands compatible for nourishment are limited, and project costs fluctuate with borrow source proximity to the shoreline. Hurricane Sandy (2012) caused high water levels and waves resulting in localized overwash and erosion in the northeastern part of NC. In response, to effectively meet the rising nourishment demands for recovery after future storm events and for long-term resiliency, the Bureau of Ocean Energy Management (BOEM) recognized the need to compile and consolidate all geophysical and geologic information in federal waters (3-8 nm) along the East Coast states. A GIS database was created for NC using bathymetric, seismic reflection, sediment and other relevant data from federal, state and private entities. Information will be accessible to the public, coastal planners and managers to allow for informed decision-making and cost-effective project planning. Priority regions for seismic and core collection were determined based on data gaps and needs across the state. In addition, potential sand resource thickness and volume in northeastern NC were revaluated using comparisons of several overlapping datasets. Shoreline volume losses were calculated using long-term erosion rates and compared to historic and future nourishment projects. Finally, tourism-based revenue by town was evaluated and related to short and long-term nourishment costs.

Presentations of the CONRAD Research Symposium : oil sands water usage workshop

International Nuclear Information System (INIS)

2004-01-01

This symposium provided a forum to exchange ideas regarding water use by the oil sands industry in Canada. The topics of discussion addressed timely issues such as corrosion control in pipelines, cumulative discharge modelling in the oil sands area, waste management schemes, the effects of potential limits on water withdrawal for thermal recovery operations and plant operations, the feasibility of geological sequestration of salts, and the impact of process-affected water on bitumen recovery. Other topics of discussion included tailings ponds management, deoxygenation of water, nanofiltration for water management, water quality for wetlands, water reuse, and water supply security. The conference featured 25 presentations, of which 17 have been indexed separately for inclusion in this database. tabs., figs

Performance of sand filters for the separations areas at the Savannah River Laboratory

International Nuclear Information System (INIS)

Orth, D.A.; Sykes, G.H.; McKibben, J.M.

1981-01-01

Two new large sand filters, 30.5 by 100 m, were constructed and put into service at the Savannah River Plant (SRP) in 1975 and 1976. These units were designed to provide final filtration of process air - one for each of the two separations areas. Eventual flow will be 4950 m 3 /min (205,000 scfm) on each unit when all facilities are connected. They were built as replacements for the original sand filters that began operation in 1954 and 1955. The new filters have been operated in parallel with the old units following partial failure of the old units from acid attack and erosion of the concrete support structure for the sand beds. The design of the new units was based on extensive tests at SRP on characteristics of different sands. The performance of the new filters meets criteria for pressure drop, flow capacity, and efficiency. The efficiencies measured by DOP test are greater than 99.98%. Parallel operation reduces air velocity through the beds, which increases efficiency. A characteristic of sand filter performance has been low apparent efficiency at low input; efficiency increases as the activity input rises. This is attributed to a small entrainment release from the large amount of activity already sorbed on the filter; this release controls and lowers the calculated efficiency at low input. An analysis of efficiency as a function of input activity projects efficiencies greater than 99.99% for large inputs that might be characteristic of large internal accidents. The data indicate that DOP efficiencies can be used in hazards analyses to determine accident consequences. Routine evaluation of filter releases can be used for surveillance to establish that performance is normal at other times

Relationships between sand and water quality at recreational beaches.

Science.gov (United States)

Phillips, Matthew C; Solo-Gabriele, Helena M; Piggot, Alan M; Klaus, James S; Zhang, Yifan

2011-12-15

Enterococci are used to assess the risk of negative human health impacts from recreational waters. Studies have shown sustained populations of enterococci within sediments of beaches but comprehensive surveys of multiple tidal zones on beaches in a regional area and their relationship to beach management decisions are limited. We sampled three tidal zones on eight South Florida beaches in Miami-Dade and Broward counties and found that enterococci were ubiquitous within South Florida beach sands although their levels varied greatly both among the beaches and between the supratidal, intertidal and subtidal zones. The supratidal sands consistently had significantly higher (p sand) than the other two zones. Levels of enterococci within the subtidal sand correlated with the average level of enterococci in the water (CFU/100mL) for the season during which samples were collected (r(s) = 0.73). The average sand enterococci content over all the zones on each beach correlated with the average water enterococci levels of the year prior to sand samplings (r(s) = 0.64) as well as the average water enterococci levels for the month after sand samplings (r(s) = 0.54). Results indicate a connection between levels of enterococci in beach water and sands throughout South Florida's beaches and suggest that the sands are one of the predominant reservoirs of enterococci impacting beach water quality. As a result, beaches with lower levels of enterococci in the sand had fewer exceedences relative to beaches with higher levels of sand enterococci. More research should focus on evaluating beach sand quality as a means to predict and regulate marine recreational water quality. Copyright © 2011 Elsevier Ltd. All rights reserved.

Short review of runoff and erosion physically based models

Directory of Open Access Journals (Sweden)

Gabrić Ognjen

2015-01-01

Full Text Available Processes of runoff and erosion are one of the main research subjects in hydrological science. Based on the field and laboratory measurements, and analogous with development of computational techniques, runoff and erosion models based on equations which describe the physics of the process are also developed. Several models of runoff and erosion which describes entire process of genesis and sediment transport on the catchment are described and compared.

Journal of Agriculture and Social Research (JASR) Vol. 11, No. 2 ...

African Journals Online (AJOL)

USER

to extensive review of official document of Abia State governments, ... Proportions of soil constituents (sand, silt, clay) are sometimes adjusted and .... painting of road median and kerbs, erosion control works, construction of roundabout and.

Managing dental erosion.

Science.gov (United States)

Curtis, Donald A; Jayanetti, Jay; Chu, Raymond; Staninec, Michal

2012-01-01

The clinical signs of dental erosion are initially subtle, yet often progress because the patient remains asymptomatic, unaware and uninformed. Erosion typically works synergistically with abrasion and attrition to cause loss of tooth structure, making diagnosis and management complex. The purpose of this article is to outline clinical examples of patients with dental erosion that highlight the strategy of early identification, patient education and conservative restorative management. Dental erosion is defined as the pathologic chronic loss of dental hard tissues as a result of the chemical influence of exogenous or endogenous acids without bacterial involvement. Like caries or periodontal disease, erosion has a multifactorial etiology and requires a thorough history and examination for diagnosis. It also requires patient understanding and compliance for improved outcomes. Erosion can affect the loss of tooth structure in isolation of other cofactors, but most often works in synergy with abrasion and attrition in the loss of tooth structure (Table 1). Although erosion is thought to be an underlying etiology of dentin sensitivity, erosion and loss of tooth structure often occurs with few symptoms. The purpose of this article is threefold: first, to outline existing barriers that may limit early management of dental erosion. Second, to review the clinical assessment required to establish a diagnosis of erosion. And third, to outline clinical examples that review options to restore lost tooth structure. The authors have included illustrations they hope will be used to improve patient understanding and motivation in the early management of dental erosion.

Investigation of Dense Sand Properties in Shallow Depth using CPT and DMT

DEFF Research Database (Denmark)

Gaydadzhiew, Dimitar Todorov; Puscasu, Ionut; Vaitkunaite, Evelina

2015-01-01

ABSTRACT: The present paper is an investigation of the soil parameters of the given Aalborg University Sand No. 1 using the Flat Dilatometer Test (DMT) and the Cone Penetration Test (CPT). This clean sand type is considered to be similar to the sands found in the North Sea area. The research...

Development of an Integrated Water and Wind Erosion Model

Science.gov (United States)

Flanagan, D. C.; Ascough, J. C.; Wagner, L. E.; Geter, W. F.

2006-12-01

Prediction technologies for soil erosion by the forces of wind or water have largely been developed independently from one another, especially within the United States. Much of this has been due to the initial creation of equations and models which were empirical in nature (i.e., Universal Soil Loss Equation, Wind Erosion Equation) and based upon separate water erosion or wind erosion plot and field measurements. Additionally, institutional organizations in place typically divided research efforts and funding to unique wind or water erosion research and modeling projects. However, during the past 20 years computer technologies and erosion modeling have progressed to the point where it is now possible to merge physical process-based computer simulation models into an integrated water and wind erosion prediction system. In a physically- based model, many of the processes which must be simulated for wind and water erosion computations are the same, e.g., climate, water balance, runoff, plant growth, etc. Model components which specifically deal with the wind or water detachment, transport and deposition processes are those that must differ, as well as any necessary parameterization of input variables (e.g., adjusted soil erodibilities, critical shear stresses, etc.) for those components. This presentation describes current efforts towards development of a combined wind and water erosion model, based in part upon technologies present in the Water Erosion Prediction Project (WEPP) and the Wind Erosion Prediction System (WEPS) models. Initial efforts during the past two years have resulted in modular modeling components that allow for prediction of infiltration, surface runoff, and water erosion at a hillslope scale within an Object Modeling System. Additional components currently in development include wind detachment at a single field point, continuous water balance, and unified plant growth. Challenges in this project are many, and include adequate field

Potensi Pasir Lokal Tanjung Bintang Pada Aluminium Sand Casting Terhadap Porositas Produk Hasil Cor Aluminium

OpenAIRE

Hendronursito, Yusup; Prayanda, Yogi

2016-01-01

Green sand is one of the most important components in the process of metal casting. The sand in Indonesia region is varied level of subtlety, size of sand, and shape of sand. Green sand used in the process of metal casting is possible can affect the quality of casting product. This aims to determine the potential of Tanjung Bintang sand as green sand and the quality of the product in terms of porosity defects. The research was conducted by varying sand river from Tanjung Bintang and sand from...

Preliminary assessment of soil erosion impact during forest restoration process

Science.gov (United States)

Lai, Yen-Jen; Chang, Cheng-Sheng; Tsao, Tsung-Ming; Wey, Tsong-Huei; Chiang, Po-Neng; Wang, Ya-Nan

2014-05-01

Taiwan has a fragile geology and steep terrain. The 921 earthquake, Typhoon Toraji, Typhoon Morakot, and the exploitation and use of the woodland by local residents have severely damaged the landscape and posed more severe challenges to the montane ecosystem. A land conservation project has been implemented by the Experimental Forest of National Taiwan University which reclaimed approximately 1,500 hectares of leased woodland from 2008 to 2010, primarily used to grow bamboo, tea trees, betel nut, fruit, and vegetable and about 1,298 hectares have been reforested. The process of forest restoration involves clear cutting, soil preparation and a six-year weeding and tending period which may affect the amount of soil erosion dramatically. This study tried to assess the impact of forest restoration from the perspective of soil erosion through leased-land recovery periods and would like to benefit the practical implementation of reforestation in the future. A new plantation reforested in the early 2013 and a nearby 29-year-old mature forest were chosen as experimental and comparison sites. A self-designed weir was set up in a small watershed of each site for the runoff and sediment yield observation. According to the observed results from May to August 2013, a raining season in Taiwan, the runoff and erosion would not as high as we expected, because the in-situ soil texture of both sites is sandy loam to sandy with high percentage of coarse fragment which increased the infiltration. There were around 200 kg to 250 kg of wet sand/soil yielded in mature forest during the hit of Typhoon Soulik while the rest of the time only suspended material be yielded at both sites. To further investigate the influence of the six-year weeding and tending period, long term observations are needed for a more completed assessment of soil erosion impact.

Application of random seismic inversion method based on tectonic model in thin sand body research

Science.gov (United States)

Dianju, W.; Jianghai, L.; Qingkai, F.

2017-12-01

The oil and gas exploitation at Songliao Basin, Northeast China have already progressed to the period with high water production. The previous detailed reservoir description that based on seismic image, sediment core, borehole logging has great limitations in small scale structural interpretation and thin sand body characterization. Thus, precise guidance for petroleum exploration is badly in need of a more advanced method. To do so, we derived the method of random seismic inversion constrained by tectonic model.It can effectively improve the depicting ability of thin sand bodies, combining numerical simulation techniques, which can credibly reducing the blindness of reservoir analysis from the whole to the local and from the macroscopic to the microscopic. At the same time, this can reduce the limitations of the study under the constraints of different geological conditions of the reservoir, accomplish probably the exact estimation for the effective reservoir. Based on the research, this paper has optimized the regional effective reservoir evaluation and the productive location adjustment of applicability, combined with the practical exploration and development in Aonan oil field.

Soil erosion in Iran: Issues and solutions

Science.gov (United States)

Hamidreza Sadeghi, Seyed; Cerdà, Artemi

2015-04-01

Iran currently faces many soil erosion-related problems (see citations below). These issues are resulted from some inherent characteristic and anthropogenic triggering forces. Nowadays, the latter plays more important rule to accelerate the erosion with further emphasis on soil erosion-prone arid and semi arid regions of the country. This contribution attempts to identify and describe the existing main reasons behind accelerated soil erosion in Iran. Appropriate solutions viz. structural and non-structural approaches will be then advised to combat or minimise the problems. Iran can be used as a pilot research site to understand the soil erosion processes in semiarid, arid and mountainous terrain and our research will review the scientific literature and will give an insight of the soil erosion rates in the main factors of the soil erosion in Iran. Key words: Anthropogenic Erosion, Land Degradation; Sediment Management; Sediment Problems Acknowledgements The research projects GL2008-02879/BTE, LEDDRA 243857 and PREVENTING AND REMEDIATING DEGRADATION OF SOILS IN EUROPE THROUGH LAND CARE (RECARE)FP7-ENV-2013- supported this research. References Aghili Nategh, N., Hemmat, A., & Sadeghi, M. (2014). Assessing confined and semi-confined compression curves of highly calcareous remolded soil amended with farmyard manure. Journal of Terramechanics, 53, 75-82. Arekhi, S., Bolourani, A. D., Shabani, A., Fathizad, H., Ahamdy-Asbchin, S. 2012. Mapping Soil Erosion and Sediment Yield Susceptibility using RUSLE, Remote Sensing and GIS (Case study: Cham Gardalan Watershed, Iran). Advances in Environmental Biology, 6(1), 109-124. Arekhi, S., Shabani, A., Rostamizad, G. 2012. Application of the modified universal soil loss equation (MUSLE) in prediction of sediment yield (Case study: Kengir Watershed, Iran). Arabian Journal of Geosciences, 5(6), 1259-1267.Sadeghi, S. H., Moosavi, V., Karami, A., Behnia, N. 2012. Soil erosion assessment and prioritization of affecting factors at plot

Assessment of sand quality on concrete performance : examination of acidic and sulfate/sulfide-bearing sands.

Science.gov (United States)

2014-12-01

The purpose of this research is to examine how the presence of sulfide- and sulfate-containing : minerals in acidic aggregates may affect the properties of mortar and concrete. Analyses were : performed to compare two sands from a deposit in the Geor...

Geomorphic and hydrologic assessment of erosion hazards at the Norman municipal landfill, Canadian River floodplain, Central Oklahoma

Science.gov (United States)

Curtis, J.A.; Whitney, J.W.

2003-01-01

The Norman, Oklahoma, municipal landfill closed in 1985 after 63 years of operation, because it was identified as a point source of hazardous leachate composed of organic and inorganic compounds. The landfill is located on the floodplain of the Canadian River, a sand-bed river characterized by erodible channel boundaries and by large variation in mean monthly discharges. In 1986, floodwaters eroded riprap protection at the southern end of the landfill and penetrated the landfill's clay cap, thereby exposing the landfill contents. The impact of this moderate-magnitude flood event (Q12) was the catalyst to investigate erosion hazards at the Norman landfill. This geomorphic investigation analyzed floodplain geomorphology and historical channel changes, flood-frequency distributions, an erosion threshold, the geomorphic effectiveness of discharge events, and other factors that influence erosion hazards at the landfill site. The erosion hazard at the Norman landfill is a function of the location of the landfill with respect to the channel thalweg, erosional resistance of the channel margins, magnitude and duration of discrete discharge events, channel form and hydraulic geometry, and cumulative effects related to a series of discharge events. Based on current climatic conditions and historical channel changes, a minimum erosion threshold is set at bankfull discharge (Q = 572 m3/s). The annual probability of exceeding this threshold is 0.53. In addition, this analysis indicates that peak stream power is less informative than total energy expenditures when estimating the erosion potential or geomorphic effectiveness of discrete discharge events. On the Canadian River, long-duration, moderate-magnitude floods can have larger total energy expenditures than shorter-duration, high-magnitude floods and therefore represent the most serious erosion hazard to floodplain structures.

A sand budget for Marble Canyon, Arizona: implications for long-term monitoring of sand storage change

Science.gov (United States)

Grams, Paul E.

2013-01-01

Recent U.S. Geological Survey research is providing important insights into how best to monitor changes in the amount of tributary-derived sand stored on the bed of the Colorado River and in eddies in Marble Canyon, Arizona. Before the construction of Glen Canyon Dam and other dams upstream, sandbars in Glen, Marble, and Grand Canyons were replenished each year by sediment-rich floods. Sand input into the Colorado River is crucial to protecting endangered native fish, animals, and plants and cultural and recreational resources along the river in Glen Canyon National Recreation Area and Grand Canyon National Park.

Comparison of erosion and erosion control works in Macedonia, Serbia and Bulgaria

Directory of Open Access Journals (Sweden)

Ivan Blinkov

2013-12-01

Natural conditions in the Balkan countries contribute to the appearance of various erosion forms and the intensity of the erosion processes. Over the history of these countries, people who settled this region used the available natural resources to fill their needs (tree cutting, incorrect plugging, overgrazing, which contributed to soil erosion. Organized erosion control works in the Balkans started in the beginning of the 20th century (1905 in Bulgaria. The highest intensity of erosion control works were carried out during the period 1945 – 1990. Various erosion control works were launched. Bulgaria had a large anti-erosion afforestation, almost 1 million ha. Bulgaria's ecological river restoration approach has been in use for almost 50 years. Serbia contributed significant erosion and torrent control works on hilly agricultural areas. Specific screen barrages and afforestation on extremely dry areas are characteristic in Macedonia. A common characteristic for all countries is a high decrease in erosion control works in the last 20 years.

Erosion-corrosion

International Nuclear Information System (INIS)

Aghili, B.

1999-05-01

A literature study on erosion-corrosion of pipings in the nuclear industry was performed. Occurred incidents are reviewed, and the mechanism driving the erosion-corrosion is described. Factors that influence the effect in negative or positive direction are treated, as well as programs for control and inspection. Finally, examples of failures from databases on erosion-corrosion are given in an attachment

Simwe model application on susceptibility analysis to linear erosion: a case study in Alto Douro wine region.

Science.gov (United States)

Fernandes, Joana; Bateira, Carlos; Soares, Laura; Faria, Ana; Moura, Rui; Gonçalves, José

2016-04-01

consistent with the lower values of electrical resistivity. The areas with the highest amount of erosive features are related to medium sediment flux values, (13.8-334.2 g/ms), medium or high transport capacity (250.3g/ms - 9.4 kg/ms), and sediment concentration with medium or very high classes where register more than 70% of gullies. These values, combined with low hydraulic conductivity with average Ks values 0.0004 cm3/s, and soil infiltration capacity with values from 0.11 to 0.36 cm/min, derives from the fine texture of soils - gravel (18.8 - 47.9%), sand (10.8 - 20.5%) and silt/clay (32.1 - 64.9%), induce an increased runoff and the development of linear erosion. The obtained results seem to indicate a good performance of the SIMWE model in the identification of the areas more susceptible to the hydric erosion of the soils, indeed, the most critical areas show the connection between the inventoried erosive forms. Keywords: Water Erosion, SIMWE, Agricultural Terraces, Alto Douro Wine Region References Mitas, H. e Mitasova, L. (1998). Distribuited Soil Erosion Simulation for effective erosion prevention. Water Resources Research, Vol. 34(3), pp. 505-516.

Prediction of Liquefaction Potential of Dredge Fill Sand by DCP and Dynamic Probing

International Nuclear Information System (INIS)

Alam, Md. Jahangir; Azad, Abul Kalam; Rahman, Ziaur

2008-01-01

From many research it is proved that liquefaction potential of sand is function of mainly relative density and confining pressure. During routine site investigations, high-quality sampling and laboratory testing of sands are not feasible because of inevitable sample disturbance effects and budgetary constraints. On the other hand quality control of sand fill can be done by determining in situ density of sand in layer by layer which is expensive and time consuming. In this paper TRL DCP (Transportation Research Laboratory Dynamic Cone Penetration) and DPL (Dynamic Probing Light) are calibrated to predict the relative density of sand deposit. For this purpose sand of known relative density is prepared in a calibration chamber which is a mild steel cylinder with diameter 0.5 m and height 1.0 m. Relative density of sand is varied by controlling height of fall and diameter of hole of sand discharge bowl. After filling, every time DPL and DCP tests are performed and for every blow the penetration of cone is recorded. N10 is then calculated from penetration records. Thus a database is compiled where N10 and relative densities are known. A correlation is made between N 10 and relative density for two types of sand. A good correlation of N 10 and relative density is found

Used Furan Sand Reclamation in REGMAS Vibratory Unit

Directory of Open Access Journals (Sweden)

Dańko J.

2015-09-01

Full Text Available The paper, especially dealt with problems of reclamation of used furan sand, carried out in new, vibratory sand reclamation unit REGMAS developed by researches from AGH-University of Science and Technology, Faculty of Foundry Engineering in Cracow (Poland. Functional characteristics of reclamation unit as well as the results of reclamation of used sand with furfuryl resin are discussed in the paper. The quality of reclaim was tested by means of the LOI and pH value, dust content in the reclaim and at least by the the quality of the castings produced in moulds prepared with the use of reclaimed matrix.

Optimization of cyclones geometry for sand pre-separation of petroleum production; Otimizacao de ciclone para a pre-separacao de areia na producao de petroleo

Energy Technology Data Exchange (ETDEWEB)

Carvalho, Aline T. de [Chemtech, Rio de Janeiro, RJ (Brazil); Medronho, Ricardo A. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Escola de Quimica

2008-07-01

Sand production in petroleum holes is a critical problem in separation plants in petroleum platforms. Sand may cause severe erosion in valves and lines and its accumulation in main process devices may force stopping the process for cleaning. This may be responsible for huge production loses. In this work, the geometrical proportions of a cyclone with high efficiency for sand-gas separation. For that, experimental design was employed to select the geometries to be studied. The separation efficiency was obtained by Computational Fluid Dynamics technique, with the commercial software CFX, version 11.0. This tool numerically solves the conservation equations, which permits estimating fluid and particles trajectory inside the equipment. Then, it was possible to obtain a model and based on that to find the geometry that gives the best efficiency to the proposed service. (author)

Oil sands economic impacts Canada : CERI report : backgrounder

International Nuclear Information System (INIS)

2005-09-01

Oil sands production now accounts for 1 out of every 2 barrels of supply in Western Canada. It is anticipated that Alberta's oil sands sector will experience significant growth over the next few decades. This paper provided an outline of the challenges and economic impacts resulting from oil sands development in Canada. Alberta's oil sands reserves are estimated at 175 billion barrels that are deemed economically recoverable using current technology. At current production levels, reserves will sustain production of 2.5 million barrels per day for the next 200 years. A study by the Canadian Energy Research Institute (CERI) has forecast $100 billion in investment for the 2000-2020 period. Numerous companies hold leases and are planning new projects. A number of recent advances in oil sands technology are expected to further reduce costs as development matures. A royalty and tax regime that provides long-term fiscal certainty is a key factor that supports current oil sands growth forecasts. The CERI study has indicated that economic spinoffs from oil sands development relate to employment generated outside of Alberta, and that the largest percentage of government revenue accrues to the federal government. However, development may be constrained because the pace of growth in the sector may exceed underlying infrastructure related to roads, housing and municipal services. An adequate workforce of qualified trades and technical and professional people is also crucial. Several pipeline projects have been proposed to deliver oil sands crudes to new markets over the next decade. It was concluded that the billions of dollars invested in oil sands in Alberta will contribute to the economic prosperity of the entire country. 11 figs

Study of Black Sand Particles from Sand Dunes in Badr, Saudi Arabia Using Electron Microscopy

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Haider Abbas Khwaja

2015-08-01

Full Text Available Particulate air pollution is a health concern. This study determines the microscopic make-up of different varieties of sand particles collected at a sand dune site in Badr, Saudi Arabia in 2012. Three categories of sand were studied: black sand, white sand, and volcanic sand. The study used multiple high resolution electron microscopies to study the morphologies, emission source types, size, and elemental composition of the particles, and to evaluate the presence of surface “coatings or contaminants” deposited or transported by the black sand particles. White sand was comprised of natural coarse particles linked to wind-blown releases from crustal surfaces, weathering of igneous/metamorphic rock sources, and volcanic activities. Black sand particles exhibited different morphologies and microstructures (surface roughness compared with the white sand and volcanic sand. Morphological Scanning Electron Microscopy (SEM and Laser Scanning Microscopy (LSM analyses revealed that the black sand contained fine and ultrafine particles (50 to 500 nm ranges and was strongly magnetic, indicating the mineral magnetite or elemental iron. Aqueous extracts of black sands were acidic (pH = 5.0. Fe, C, O, Ti, Si, V, and S dominated the composition of black sand. Results suggest that carbon and other contaminant fine particles were produced by fossil-fuel combustion and industrial emissions in heavily industrialized areas of Haifa and Yanbu, and transported as cloud condensation nuclei to Douf Mountain. The suite of techniques used in this study has yielded an in-depth characterization of sand particles. Such information will be needed in future environmental, toxicological, epidemiological, and source apportionment studies.

Extremely low long-term erosion rates around the Gamburtsev Mountains in interior East Antarctica

Science.gov (United States)

Cox, S. E.; Thomson, S. N.; Reiners, P. W.; Hemming, S. R.; van de Flierdt, T.

2010-11-01

The high elevation and rugged relief (>3 km) of the Gamburtsev Subglacial Mountains (GSM) have long been considered enigmatic. Orogenesis normally occurs near plate boundaries, not cratonic interiors, and large-scale tectonic activity last occurred in East Antarctica during the Pan-African (480-600 Ma). We sampled detrital apatite from Eocene sands in Prydz Bay at the terminus of the Lambert Graben, which drained a large pre-glacial basin including the northern Gamburtsev Mountains. Apatite fission-track and (U-Th)/He cooling ages constrain bedrock erosion rates throughout the catchment. We double-dated apatites to resolve individual cooling histories. Erosion was very slow, averaging 0.01-0.02 km/Myr for >250 Myr, supporting the preservation of high elevation in interior East Antarctica since at least the cessation of Permian rifting. Long-term topographic preservation lends credence to postulated high-elevation mountain ice caps in East Antarctica since at least the Cretaceous and to the idea that cold-based glaciation can preserve tectonically inactive topography.

Effect of River Indus Sand on Concrete Tensile Strength

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M. T. Lakhiar

2018-04-01

Full Text Available In the development of Pakistan construction industry, the utilization of River Indus sand in concrete as fine aggregate has expanded tremendously. The aim of this research is to study the effect of Indus River sand on the tensile strength of various grades of concrete when it is utilized as fine aggregate. Concrete Samples of M15, M20 and M25 grade concrete were cured for 7, 14, 21 and 28 days. Based on the results, it is found that concrete became less workable when Indus river sand was utilized. It is recorded that tensile strength of concrete is decreased from 5% up to 20% in comparison with hill sand. The results were derived from various concrete grades.

Advances in modeling soil erosion after disturbance on rangelands

Science.gov (United States)

Research has been undertaken to develop process based models that predict soil erosion rate after disturbance on rangelands. In these models soil detachment is predicted as a combination of multiple erosion processes, rain splash and thin sheet flow (splash and sheet) detachment and concentrated flo...

Formation of accessory mineral bed layers during erosion of bentonite buffer material

International Nuclear Information System (INIS)

Schatz, Timothy; Kanerva, Noora

2012-01-01

(kaolin, quartz sand, chromatographic silica). The resulting mixtures were compacted into dense sample tablets with effective montmorillonite dry densities between 1.4 to 1.6 g/cm 3 . The fracture erosion tests were performed using a Grimsel groundwater simulant (relative to Na + and Ca 2+ concentration only) contact solution at an average flow rate of 0.09 ml/min through the system. In colloid filtration theories, the filter bed is modelled as an assemblage of single or unit collectors having a known geometry. According to Richards [2010], the particle size distribution of the accessory minerals in MX-80 bentonite consists of particles with sizes less than 30 μm. Of the additive materials used in this study, the kaolin material consists of particles with sizes less than 20 μm showing a peak size of 6 μm, the chromatographic silica consists of particles with sizes narrowly distributed between 10 to 14 μm, and the sand consists of particles with sizes between 160 to 550 μm at a peak size of 280 μm. The tests were designed to lead to the development of erosive conditions (i.e., sodium montmorillonite against a dilute solution) and, in every case, the formation of an accessory mineral bed layer near the extrusion/erosion interface was observed. Moreover, these layers grew progressively in thickness over the course of the tests. These results provide evidence that, following erosive loss of colloidal montmorillonite through contact with dilute groundwater at a transmissive fracture interface, accessory phases (within bentonite) remain behind and form bed layers

Evaluating the oil sands reclamation process: Assessing policy capacity and stakeholder access for government and non-governmental organizations operating in Alberta's oil sands

Science.gov (United States)

Patterson, Tyler

By employing interpretive policy analysis this thesis aims to assess, measure, and explain policy capacity for government and non-government organizations involved in reclaiming Alberta's oil sands. Using this type of analysis to assess policy capacity is a novel approach for understanding reclamation policy; and therefore, this research will provide a unique contribution to the literature surrounding reclamation policy. The oil sands region in northeast Alberta, Canada is an area of interest for a few reasons; primarily because of the vast reserves of bitumen and the environmental cost associated with developing this resource. An increase in global oil demand has established incentive for industry to seek out and develop new reserves. Alberta's oil sands are one of the largest remaining reserves in the world, and there is significant interest in increasing production in this region. Furthermore, tensions in several oil exporting nations in the Middle East remain unresolved, and this has garnered additional support for a supply side solution to North American oil demands. This solution relies upon the development of reserves in both the United States and Canada. These compounding factors have contributed to the increased development in the oil sands of northeastern Alberta. Essentially, a rapid expansion of oil sands operations is ongoing, and is the source of significant disturbance across the region. This disturbance, and the promises of reclamation, is a source of contentious debates amongst stakeholders and continues to be highly visible in the media. If oil sands operations are to retain their social license to operate, it is critical that reclamation efforts be effective. One concern non-governmental organizations (NGOs) expressed criticizes the current monitoring and enforcement of regulatory programs in the oil sands. Alberta's NGOs have suggested the data made available to them originates from industrial sources, and is generally unchecked by government

Unconfined Groundwater Dispersion Model On Sand Layers In Coral Island

OpenAIRE

Sultan

2016-01-01

The research objective is to analyze the sand layer to determine the characteristics of the unconfined groundwater aquifer on coral island and found the dispersion model of unconfined groundwater in the sand layer in the coral island. The method used is direct research in the field, laboratory analysis and secondary data. Observations geological conditions, as well as the measurement and interpretation of geoelectrical potential groundwater models based on the value of the conductivity of gro...

Dental erosion in groups of Yemeni children and adolescents and the modification of an erosion partial recording system.

Science.gov (United States)

Al-Ashtal, Amin; Johansson, Anders; Omar, Ridwaan; Johansson, Ann-Katrin

2017-07-01

The prevalence of dental erosion is rising especially among children and adolescents and its grading needs further investigation. To determine the prevalence and severity of dental erosion in groups of Yemeni children and adolescents, and to clinically compare an erosion partial recording system (EPRS) with a proposed modified-simplified version (EPRS-M). Of 6163 individuals aged 5-6, 13-14 and 18-19 years, 911 were randomly selected, of which 668 participated in the study. Dental erosion was graded using EPRS. EPRS-M was proposed, and its sensitivity and specificity was calculated in relation to EPRS. Prevalence of erosion extending into dentine on at least one tooth was 6.8% among 5- to 6-year-olds, 3.0% among 13- to 14-year-olds and 14.6% among 18- to 19-year olds. The highest prevalence was 19.2% among girls aged 18-19 years which was significantly higher than boys (10.4%) in the same age group (P = 0.044). Sensitivity and specificity for EPRS-M in relation to EPRS were 85.7% and 100% for primary teeth, and 84.1% and 100% for permanent teeth. Dental erosion was common among children and older teenagers and highest among older girls but less common among younger teenagers. The tested accuracy of EPRS-M qualifies it to be used as an initial quick detection tool in future dental erosion research. © 2016 The Authors. International Journal of Paediatric Dentistry published by BSPD, IAPD and John Wiley & Sons Ltd.

Environmental hazards and distribution of radioactive black sand along the Rosetta coastal zone in Egypt using airborne spectrometric and remote sensing data

International Nuclear Information System (INIS)

Kaiser, M.F.; Aziz, A.M.; Ghieth, B.M.

2014-01-01

High-resolution airborne gamma ray spectrometry, conducted in 2003, was used to estimate radioactive elements spatial abundance along the Rosetta coastal zone area. It was noticed that both Uranium and Thorium are concentrated in the black sand deposits along the beach. In contrary, Potassium was observed in high level abundance at the cultivated Nile Delta lands due to the accumulated usage of fertilizers. Exposure Rate (ER), Absorbed Dose Rate (ADR) and Annual Effective Dose Rate (AEDR) were calculated to evaluate the radiation background influence in human. Results indicated that the human body in the study sites is subjected to radiation hazards exceeds the accepted limit for long duration exposure. In addition, the areas covered by the highest concentration of Uranium and Thorium show the highest level of radiogenic heat production. Detection the environmental hazards of the radioactive black sands in the study site encouraged this research to monitor the spatial and temporal distribution of these sediments. The Landsat Thematic Mapper images acquired in 1990, 2003 and 2013 were analyzed using remote sensing image processing techniques. Image enhancements, classification and changes detection indicated a positive significant relationship between the patterns of coastline changes and distribution of the radioactive black sand in the study sites. The radioactive black sands are usually concentrated in the eroded areas. Therefore, in 1990 high concentration of the radioactive black sands were observed along the eastern and western flanks of the Rosetta promontory. Distribution of these sediments decreased due to the construction of the protective sea walls. Most of the radioactive black sands are transported toward the east in Abu Khashaba bay under the effect of the longshore currents and toward the west in Alexandria and Abu Quir bay under the action of the seasonal reverse currents. - Highlights: • Spatial and temporal distributions of the black sand were

Water repellency of clay, sand and organic soils in Finland

Directory of Open Access Journals (Sweden)

K. RASA

2008-12-01

Full Text Available Water repellency (WR delays soil wetting process, increases preferential flow and may give rise to surface runoff and consequent erosion. WR is commonly recognized in the soils of warm and temperate climates. To explore the occurrence of WR in soils in Finland, soil R index was studied on 12 sites of different soil types. The effects of soil management practice, vegetation age, soil moisture and drying temperature on WR were studied by a mini-infiltrometer with samples from depths of 0-5 and 5-10 cm. All studied sites exhibited WR (R index >1.95 at the time of sampling. WR increased as follows: sand (R = 1.8-5.0 < clay (R = 2.4-10.3 < organic (R = 7.9-undefined. At clay and sand, WR was generally higher at the soil surface and at the older sites (14 yr., where organic matter is accumulated. Below 41 vol. % water content these mineral soils were water repellent whereas organic soil exhibited WR even at saturation. These results show that soil WR also reduces water infiltration at the prevalent field moisture regime in the soils of boreal climate. The ageing of vegetation increases WR and on the other hand, cultivation reduces or hinders the development of WR.;

Soil erosion in a man-made landscape: the Mediterranean

Science.gov (United States)

Cerdà, A.; Ruiz Sinoga, J. D.; Cammeraat, L. H.

2012-04-01

the Mediterranean lands. The methods applied to measure or estimate the soil erosion should be improved to make them comparable. An agreement is necessary to decide the size of the plots, the material and equipment to be used and the future research topics. This research study is being supported by the the research project CGL2008-02879/BTE

Soil erosion and management activities on forested slopes

Science.gov (United States)

Robert R. Ziemer

1986-01-01

Some of the most productive forests in the Western United States grow on marginally stable mountainous slopes, where disturbance increases the likelihood of erosion. Much of the public's concern about, and, consequently, most of the research on, erosion from these forested areas is related more to the degradation of stream resources by eroded material than to the...

Final IAEA research coordination meeting on plasma-interaction induced erosion of fusion reactor materials. October 9-11, 1995, Vienna, Austria. Summary report

International Nuclear Information System (INIS)

Langley, R.A.

1995-12-01

The proceedings and results of the Final IAEA Research Coordination Meeting on ''Plasma-interaction Induced Erosion of Fusion Reactor Materials'' held on October 9, 10 and 11, 1995 at the IAEA Headquarters in Vienna are briefly described. This report includes a summary of presentations made by the meeting participants, the results of a data survey and needs assessment for the erosion of plasma facing components and in-vessel materials, and recommendations regarding future work. (author). Refs, figs, tabs

Landscape Erosion Assessment using the {sup 137}Cs-based Method through Laboratory and in-situ Gamma Spectrometry: An Update of On-going Research and Progress

Energy Technology Data Exchange (ETDEWEB)

Gonsalves, B. C.; Toloza, A.; Augustin, F.; Dercon, G.; Mabit, L. [Soil and Water Management and Crop Nutrition Laboratory (SWMCNL), Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, Seibersdorf (Austria); Darby, I. G.; Kaiser, R. B. [Nuclear Science and Instrumentation Laboratory (NSIL), Division of Physical and Chemical Sciences, Seibersdorf (Austria)

2014-07-15

The objective of this research is to compare in-situ {sup 137}Cs measurements using an on-site lanthanum bromide (LaBr{sub 3} (Ce)) scintillation detector with those from a conventional laboratory-based HPGe detector to assess soil erosion. We aimed to establish (i) the strength of the relationship between in-situ and laboratory based measurements, and (ii) to develop improved tools for landscape-based soil erosion assessments in our continuing research, reported in the January 2013 Soils Newsletter.

New generation expandable sand screens

OpenAIRE

Syltøy, Christer

2014-01-01

Master's thesis in Petroleum engineering This thesis aims to give a general insight into sand control and various sorts of sand control measures and applications of sand control tools. Special focus will be given to expandable sand screens – a technology which came about in the late 1990’s through the use of flexible, expandable tubulars as base pipe in sand screens. More specifically Darcy’s Hydraulic Endurance Screens, a compliant sand screen system using hydraulic activation, and the fu...

Efficiency of Micro-fine Cement Grouting in Liquefiable Sand

International Nuclear Information System (INIS)

Mirjalili, Mojtaba; Mirdamadi, Alireza; Ahmadi, Alireza

2008-01-01

In the presence of strong ground motion, liquefaction hazards are likely to occur in saturated cohesion-less soils. The risk of liquefaction and subsequent deformation can be reduced by various ground improvement methods including the cement grouting technique. The grouting method was proposed for non-disruptive mitigation of liquefaction risk at developed sites susceptible to liquefaction. In this research, a large-scale experiment was developed for assessment of micro-fine cement grouting effect on strength behavior and liquefaction potential of loose sand. Loose sand samples treated with micro-fine grout in multidirectional experimental model, were tested under cyclic and monotonic triaxial loading to investigate the influence of micro-fine grout on the deformation properties and pore pressure response. The behavior of pure sand was compared with the behavior of sand grouted with a micro-fine cement grout. The test results were shown that cement grouting with low concentrations significantly decreased the liquefaction potential of loose sand and related ground deformation

Conditions and processes affecting sand resources at archeological sites in the Colorado River corridor below Glen Canyon Dam, Arizona

Science.gov (United States)

East, Amy E.; Collins, Brian D.; Sankey, Joel B.; Corbett, Skye C.; Fairley, Helen C.; Caster, Joshua J.

2016-05-17

This study examined links among fluvial, aeolian, and hillslope geomorphic processes that affect archeological sites and surrounding landscapes in the Colorado River corridor downstream from Glen Canyon Dam, Arizona. We assessed the potential for Colorado River sediment to enhance the preservation of river-corridor archeological resources through aeolian sand deposition or mitigation of gully erosion. By identifying locally prevailing wind directions, locations of modern sandbars, and likely aeolian-transport barriers, we determined that relatively few archeological sites are now ideally situated to receive aeolian sand supply from sandbars deposited by recent controlled floods. Whereas three-fourths of the 358 river-corridor archeological sites we examined include Colorado River sediment as an integral component of their geomorphic context, only 32 sites currently appear to have a high degree of connectivity (coupled interactions) between modern fluvial sandbars and sand-dominated landscapes downwind. This represents a substantial decrease from past decades, as determined by aerial-photograph analysis. Thus, we infer that recent controlled floods have had a limited, and declining, influence on archeological-site preservation.

Saltation of non-spherical sand particles.

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Zhengshi Wang

Full Text Available Saltation is an important geological process and the primary source of atmospheric mineral dust aerosols. Unfortunately, no studies to date have been able to precisely reproduce the saltation process because of the simplified theoretical models used. For example, sand particles in most of the existing wind sand movement models are considered to be spherical, the effects of the sand shape on the structure of the wind sand flow are rarely studied, and the effect of mid-air collision is usually neglected. In fact, sand grains are rarely round in natural environments. In this paper, we first analyzed the drag coefficients, drag forces, and starting friction wind speeds of sand grains with different shapes in the saltation process, then established a sand saltation model that considers the coupling effect between wind and the sand grains, the effect of the mid-air collision of sand grains, and the effect of the sand grain shape. Based on this model, the saltation process and sand transport rate of non-spherical sand particles were simulated. The results show that the sand shape has a significant impact on the saltation process; for the same wind speed, the sand transport rates varied for different shapes of sand grains by as much as several-fold. Therefore, sand shape is one of the important factors affecting wind-sand movement.

Enabling technologies for oil sands development

International Nuclear Information System (INIS)

Bailey, R.T.

1998-01-01

A review of oil sands production and expansion possibilities in Alberta were presented. The enabling technologies for oil sands projects include mining (bucketwheels, draglines, trucks, shovels conveyors, slurry hydrotransport); extraction (conditioning tumblers, pipelines, tanks, hot water, caustic, cold water, frothers); froth cleaning (centrifuges, solvent treatment); tailings (tailings ponds, consolidated tailings); and upgrading (coking, hydrotreating for SCO, hydrocracking and multiple products). The enabling technologies for in situ production include cyclic steam stimulation for vertical wells, steam assisted gravity drainage (SAGD) for dual horizontal wells, and cold production with wormholes. This paper described the recovery potentials of each of these processes. It also discussed the role of government and industry in research and cooperative research involving both the private and public sectors. Examples of each of these were described such as SAGD, the OSLO cold water extraction process, The consolidated tailings (CT) project, the low energy extraction process (slurry production, hydrotransport, pipeline conditioning and warm water extraction), and research in fine tailings, to demonstrate that although objectives may differ, government and industry research objectives are complementary

Data for Erosion and Tritium Retention in Beryllium Plasma-Facing Materials. Summary Report of the First Research Coordination Meeting

International Nuclear Information System (INIS)

Braams, B.J.

2013-04-01

Nine experts in the field of plasma-wall interaction on beryllium surfaces together with IAEA staff met at IAEA Headquarters 26-28 September 2012 for the First Research Coordination Meeting of an IAEA Coordinated Research Project on data for erosion and tritium retention in beryllium plasma-facing materials. They described their on-going research, reviewed the main data needs and made plans for coordinated research during the remaining years of the project. The proceedings of the meeting are summarized in this report. (author)

Interactive effects of moss-dominated crusts and Artemisia ordosica on wind erosion and soil moisture in Mu Us sandland, China.

Science.gov (United States)

Yang, Yongsheng; Bu, Chongfeng; Mu, Xingmin; Shao, Hongbo; Zhang, Kankan

2014-01-01

To better understand the effects of biological soil crusts (BSCs) on soil moisture and wind erosion and study the necessity and feasibility of disturbance of BSCs in the Mu Us sandland, the effects of four treatments, including moss-dominated crusts alone, Artemisia ordosica alone, bare sand, and Artemisia ordosica combined with moss-dominated crusts, on rainwater infiltration, soil moisture, and annual wind erosion were observed. The major results are as follows. (1) The development of moss-dominated crusts exacerbated soil moisture consumption and had negative effects on soil moisture in the Mu Us sandland. (2) Moss-dominated crusts significantly increased soil resistance to wind erosion, and when combined with Artemisia ordosica, this effect became more significant. The contribution of moss-dominated crusts under Artemisia ordosica was significantly lower than that of moss-dominated crusts alone in sites where vegetative coverage > 50%. (3) Finally, an appropriate disturbance of moss-dominated crusts in the rainy season in sites with high vegetative coverage improved soil water environment and vegetation succession, but disturbance in sites with little or no vegetative cover should be prohibited to avoid the exacerbation of wind erosion.

Erosion and its rate on an accumulative Polish dune coast: the effects of the January 2012 storm surge

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Tomasz A. Łabuz

2014-01-01

Full Text Available The Polish coast is a non-tidal area; its shores are affected mainly by autumn-winter storm surges. Those of 6 and 14 January 2012 are representative of the forces driving the erosion of normally accumulative sections of coastal dunes, monitored by the author since 1997. The sea level maximum during these two storm surges reached 1.2 to 1.5 m amsl along the Polish coast. Land forms up to 3 m amsl were inundated. Beaches and low parts of the coast up to this height were rebuilt by sea waves attacking the coast for almost 12 days. Quantitative analyses of the morphological dynamics of the coastal dunes are presented for 57 profiles located along the coast. Only those accumulative sections of the Polish coast are analysed where sand accumulation did occur and led to new foredune development. The mean rate of dune erosion was 2.5 m3 per square metre with an average toe retreat of 1.4 m. Erosion understood as dune retreat was greater when a beach was lower (correlation coefficient 0.8. Dune erosion did not occur on coasts with beaches higher than 3.2 m or on lower ones covered by embryo dunes.

Wave-current induced erosion of cohesive riverbanks in northern Manitoba, Canada

Science.gov (United States)

Kimiaghalam, N.; Clark, S.; Ahmari, H.; Hunt, J.

2015-03-01

The field of cohesive soil erosion is still not fully understood, in large part due to the many soil parameters that affect cohesive soil erodibility. This study is focused on two channels, 2-Mile and 8-Mile channels in northern Manitoba, Canada, that were built to connect Lake Winnipeg with Playgreen Lake and Playgreen Lake with Kiskikittogisu Lake, respectively. The banks of the channels consist of clay rich soils and alluvial deposits of layered clay, silts and sands. The study of erosion at the sites is further complicated because the flow-induced erosion is combined with the effects of significant wave action due to the large fetch length on the adjacent lakes, particularly Lake Winnipeg that is the seventh largest lake in North America. The study included three main components: field measurements, laboratory experiments and numerical modelling. Field measurements consisted of soil sampling from the banks and bed of the channels, current measurements and water sampling. Grab soil samples were used to measure the essential physical and electrochemical properties of the riverbanks, and standard ASTM Shelby tube samples were used to estimate the critical shear stress and erodibility of the soil samples using an erosion measurement device (EMD). Water samples were taken to estimate the sediment concentration profile and also to monitor changes in sediment concentration along the channels over time. An Acoustic Doppler Current Profiler (ADCP) was used to collect bathymetry and current data, and two water level gauges have been installed to record water levels at the entrance and outlet of the channels. The MIKE 21 NSW model was used to simulate waves using historical winds and measured bathymetry of the channels and lakes. Finally, results from the wave numerical model, laboratory tests and current measurement were used to estimate the effect of each component on erodibility of the cohesive banks.

Wave-current induced erosion of cohesive riverbanks in northern Manitoba, Canada

Directory of Open Access Journals (Sweden)

N. Kimiaghalam

2015-03-01

Full Text Available The field of cohesive soil erosion is still not fully understood, in large part due to the many soil parameters that affect cohesive soil erodibility. This study is focused on two channels, 2-Mile and 8-Mile channels in northern Manitoba, Canada, that were built to connect Lake Winnipeg with Playgreen Lake and Playgreen Lake with Kiskikittogisu Lake, respectively. The banks of the channels consist of clay rich soils and alluvial deposits of layered clay, silts and sands. The study of erosion at the sites is further complicated because the flow-induced erosion is combined with the effects of significant wave action due to the large fetch length on the adjacent lakes, particularly Lake Winnipeg that is the seventh largest lake in North America. The study included three main components: field measurements, laboratory experiments and numerical modelling. Field measurements consisted of soil sampling from the banks and bed of the channels, current measurements and water sampling. Grab soil samples were used to measure the essential physical and electrochemical properties of the riverbanks, and standard ASTM Shelby tube samples were used to estimate the critical shear stress and erodibility of the soil samples using an erosion measurement device (EMD. Water samples were taken to estimate the sediment concentration profile and also to monitor changes in sediment concentration along the channels over time. An Acoustic Doppler Current Profiler (ADCP was used to collect bathymetry and current data, and two water level gauges have been installed to record water levels at the entrance and outlet of the channels. The MIKE 21 NSW model was used to simulate waves using historical winds and measured bathymetry of the channels and lakes. Finally, results from the wave numerical model, laboratory tests and current measurement were used to estimate the effect of each component on erodibility of the cohesive banks.

Reflux disease as an etiological factor of dental erosion

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Stojšin Ivana

2010-01-01

Full Text Available Introduction Gastroesophageal reflux is a frequent disease which has a significant influence on the development of dental erosions. Objective The aim of this research was to determine the frequency of dental erosions among the patients with gastroesophageal reflux, as well as to verify the most common symptoms of gastroesophageal disease. Methods The research comprised of two groups, each consisting of 30 patients aged 18-80 years. The experimental group comprised of patients diagnosed with gastroesophageal reflux disease (GERD, while the control group was composed of patients who were not diagnosed with GERD. Based on the illness history data, all patients of the experimental group were registered to have gastroesophageal and extraesophageal symptoms. Dental erosions were diagnosed during a stomatological inspection by using index system according to Eccles and Jenkins. Data processing was accomplished by the Statgraphics Centurion software package. Results Dental erosions were found in 76.7% of experimental group patients, and in 53.3% of control group patients. Fortynine percent of teeth of the experimental group patients and 31.1% of the control group patients showed erosive changes. On average, the number of teeth with erosions in the experimental group was 15.7 per person and in the control group 10 per person. The teeth of the front region of the upper jaw, as well as the lower first molars had the highest average value of dental erosion index. In the experimental group 12.8% of teeth and 24% of teeth in the control group were diagnosed to have dental erosion index value 1. Furthermore, 23.4% of teeth in the experimental group and 7.1% of teeth in the control group were registered to have dental erosion index value 2. Finally, the dental erosion index value 3 was found in 13.0% of teeth in the experimental group only. The highest average value of regional erosion index in the experimental group was found in the region 13-23 equalling 1

Rainfall erosivity factor estimation in Republic of Moldova

Science.gov (United States)

Castraveš, Tudor; Kuhn, Nikolaus

2017-04-01

Rainfall erosivity represents a measure of the erosive force of rainfall. Typically, it is expressed as variable such as the R factor in the Universal Soil Loss Equation (USLE) (Wischmeier and Smith, 1965, 1978) or its derivates. The rainfall erosivity index for a rainfall event (EI30) is calculated from the total kinetic energy and maximum 30 minutes intensity of individual events. However, these data are often unavailable for wide regions and countries. Usually, there are three issues regarding precipitation data: low temporal resolution, low spatial density and limited access to the data. This is especially true for some of postsoviet countries from Eastern Europe, such as Republic of Moldova, where soil erosion is a real and persistent problem (Summer, 2003) and where soils represents the main natural resource of the country. Consequently, researching and managing soil erosion is particularly important. The purpose of this study is to develop a model based on commonly available rainfall data, such as event, daily or monthly amounts, to calculate rainfall erosivity for the territory of Republic of Moldova. Rainfall data collected during 1994-2015 period at 15 meteorological stations in the Republic of Moldova, with 10 minutes temporal resolution, were used to develop and calibrate a model to generate an erosivity map of Moldova. References 1. Summer, W., (2003). Soil erosion in the Republic of Moldova — the importance of institutional arrangements. Erosion Prediction in Ungauged Basins: Integrating Methods and Techniques (Proceedings of symposium HS01 held during IUGG2003 at Sapporo. July 2003). IAHS Publ. no. 279. 2. Wischmeier, W.H., and Smith, D.D. (1965). Predicting rainfall-erosion losses from cropland east of the Rocky Mountains. Agr. Handbook No. 282, U.S. Dept. Agr., Washington, DC 3. Wischmeier, W.H., and Smith, D.D. (1978). Predicting rainfall erosion losses. Agr. handbook No. 537, U.S. Dept. of Agr., Science and Education Administration.

The history of human-induced soil erosion: Geomorphic legacies, early descriptions and research, and the development of soil conservation—A global synopsis

Science.gov (United States)

Dotterweich, Markus

2013-11-01

This paper presents a global synopsis about the geomorphic evidence of soil erosion in humid and semihumid areas since the beginning of agriculture. Historical documents, starting from ancient records to data from the mid-twentieth century and numerous literature reviews form an extensive assortment of examples that show how soil erosion has been perceived previously by scholars, land surveyors, farmers, land owners, researchers, and policy makers. Examples have been selected from ancient Greek and Roman Times and from central Europe, southern Africa, North America, the Chinese Loess Plateau, Australia, New Zealand, and Easter Island. Furthermore, a comprehensive collection on the development of soil erosion research and soil conservation has been provided, with a particular focus on Germany and the USA. Geomorphic evidence shows that most of the agriculturally used slopes in the Old and New Worlds had already been affected by soil erosion in earlier, prehistoric times. Early descriptions of soil erosion are often very vague. With regard to the Roman Times, geomorphic evidence shows seemingly opposing results, ranging from massive devastation to landscapes remaining stable for centuries. Unfortunately, historical documentation is lacking. In the following centuries, historical records become more frequent and more precise and observations on extreme soil erosion events are prominent. Sometimes they can be clearly linked to geomorphic evidence in the field. The advent of professional soil conservation took place in the late eighteenth century. The first extensive essay on soil conservation known to the Western world was published in Germany in 1815. The rise of professional soil conservation occurred in the late nineteenth and early twentieth centuries. Soil remediation and flood prevention programs were initiated, but the long-term success of these actions remains controversial. In recent years, increasing interest is to recover any traditional knowledge of soil

Nuclear energy in the oils sands

International Nuclear Information System (INIS)

Arsenault, J.E.

2014-01-01

The major Canadian oil sands are located in Alberta and Saskatchewan, with most production from the strata along the Athabasca River in Alberta. The economically recoverable oil sands reserves are estimated to be 168 billion barrels which at a current production rate of 1.8 million barrels per day (2012), are projected to last a very long time. Canada has been blessed with vast energy resources which make it potentially energy-independent and able to provide significant exports but there are concerns that their development cannot be managed in a wholly acceptable manner. Comparable concerns have been applied to nuclear energy in the past and in recent times to the oil sands. The technologies associated with these energy sources have always been controversial because they are at the confluence of economics and politics where finding a balance between risk and reward is difficult. So it should be no surprise that when these technologies get linked together in certain proposals their prospect for success is doubly difficult. The possible use of nuclear energy for production of oil from the oil sands dates back to the late 1950s, when an experiment to mine the oil by detonating an underground nuclear device was proposed. It was predicted that the heat and pressure released from such a device would create a large cavern into which oil would flow, and from where it would be pumped to the surface. Almost at the same time, oil sands research using conventional sources of energy had culminated with the development of practical refining processes, essentially those still in use today. These methods require large amounts of heat energy in the form of hot water and steam. In this century nuclear energy was proposed as the source for the heat required by the oil sands production processes. To date neither of these nuclear proposals for oil sands projects have been successful, because the economic and political balance could not be struck. (author)

Nuclear energy in the oils sands

Energy Technology Data Exchange (ETDEWEB)

Arsenault, J.E.

2014-09-15

The major Canadian oil sands are located in Alberta and Saskatchewan, with most production from the strata along the Athabasca River in Alberta. The economically recoverable oil sands reserves are estimated to be 168 billion barrels which at a current production rate of 1.8 million barrels per day (2012), are projected to last a very long time. Canada has been blessed with vast energy resources which make it potentially energy-independent and able to provide significant exports but there are concerns that their development cannot be managed in a wholly acceptable manner. Comparable concerns have been applied to nuclear energy in the past and in recent times to the oil sands. The technologies associated with these energy sources have always been controversial because they are at the confluence of economics and politics where finding a balance between risk and reward is difficult. So it should be no surprise that when these technologies get linked together in certain proposals their prospect for success is doubly difficult. The possible use of nuclear energy for production of oil from the oil sands dates back to the late 1950s, when an experiment to mine the oil by detonating an underground nuclear device was proposed. It was predicted that the heat and pressure released from such a device would create a large cavern into which oil would flow, and from where it would be pumped to the surface. Almost at the same time, oil sands research using conventional sources of energy had culminated with the development of practical refining processes, essentially those still in use today. These methods require large amounts of heat energy in the form of hot water and steam. In this century nuclear energy was proposed as the source for the heat required by the oil sands production processes. To date neither of these nuclear proposals for oil sands projects have been successful, because the economic and political balance could not be struck. (author)

Coupling erosion and topographic development in the rainiest place on Earth: Reconstructing the Shillong Plateau uplift history with in-situ cosmogenic 10Be

Science.gov (United States)

Rosenkranz, Ruben; Schildgen, Taylor; Wittmann, Hella; Spiegel, Cornelia

2018-02-01

The uplift of the Shillong Plateau, in northeast India between the Bengal floodplain and the Himalaya Mountains, has had a significant impact on regional precipitation patterns, strain partitioning, and the path of the Brahmaputra River. Today, the plateau receives the highest measured yearly rainfall in the world and is tectonically active, having hosted one of the strongest intra-plate earthquakes ever recorded. Despite the unique tectonic and climatic setting of this prominent landscape feature, its exhumation and surface uplift history are poorly constrained. We collected 14 detrital river sand and 3 bedrock samples from the southern margin of the Shillong Plateau to measure erosion rates using the terrestrial cosmogenic nuclide 10Be. The calculated bedrock erosion rates range from 2.0 to 5.6 m My-1, whereas catchment average erosion rates from detrital river sands range from 48 to 214 m My-1. These rates are surprisingly low in the context of steep, tectonically active slopes and extreme rainfall. Moreover, the highest among these rates, which occur on the low-relief plateau surface, appear to have been affected by anthropogenic land-use change. To determine the onset of surface uplift, we coupled the catchment averaged erosion rates with topographic analyses of the plateau's southern margin. We interpolated an inclined, pre-incision surface from minimally eroded remnants along the valley interfluves and calculated the eroded volume of the valleys carved beneath the surface. The missing volume was then divided by the volume flux derived from the erosion rates to obtain the onset of uplift. The results of this calculation, ranging from 3.0 to 5.0 Ma for individual valleys, are in agreement with several lines of stratigraphic evidence from the Brahmaputra and Bengal basin that constrain the onset of topographic uplift, specifically the onset of flexural loading and the transgression from deltaic to marine deposition. Ultimately, our data corroborate the

Effects of sea level rise on the formation and drowning of shoreface-connected sand ridges, a model study

Science.gov (United States)

Nnafie, A.; de Swart, H. E.; Calvete, D.; Garnier, R.

2014-06-01

Shoreface-connected sand ridges occur on many storm-dominated inner shelves. These rhythmic features have an along-shelf spacing of 2-10 km, a height of 1-12 m, they evolve on timescales of centuries and they migrate several meters per year. An idealized model is used to study the impact of sea level rise on the characteristics of the sand ridges during their initial and long-term evolution. Different scenarios (rates of sea level rise, geometry of inner shelf) are examined. Results show that with increasing sea level the height of sand ridges increases and their migration decreases until they eventually drown. This latter occurs when the near-bed wave orbital velocity drops below the critical velocity for erosion of sediment. In contrast, in the absence of sea level rise, the model simulates shoreface-connected sand ridges with constant heights and migration rates. Model results furthermore indicate that sand ridges do not form if the rate of sea level rise is too high, or if the initial depth of the inner shelf is too small. A larger transverse bottom slope enhances growth and height of sand ridges and they drown quicker. When shoreface retreat due to sea level rise is considered, new ridges form in the landward part of the inner shelf, while ridges on the antecedent part of the shelf become less active and ultimately drown. Only if sea level rise is accounted for, merging of ridges is reduced such that multiple ridges occur in the end state, thereby yielding a better agreement with observations. The physical mechanisms responsible for these findings are also explained.

Determination of effective factors on the occurrence of digitated gully erosion in the AghEmam(2 watershed

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Maryam Mohammad Ebrahimi

2017-03-01

´ 19˝ northern latitudes in the east parts of the Golestan province with an area of 2,595 hectares. Arab gharehaji rural is considered as the most important area which is located at the outlet of the basin. In current study, at first, frame work and total surface of the area were investigated by field observations and 9 digitated gullies were observed during field observations. Then, spatial position of each gully was determined by using global positioning system and map of gully distribution was obtained for the study area. Then, by overlaying this map on lithology, slope degree and altitude maps of the study area, the mentioned characteristics were determined for the gullies. After sampling from the soil, they were carried to the lab and clay percentage, silt percentage, sand percentage, saturation humid percentage, electrical conductivity, acidity, organic matter percentage, exchangeable sodium percentage, sodium absorption ratio, percentage of neutrophil materials for two considered depths were measured. Then, two statistical tests were applied in order to determine the significance and or non- significance of different physical and chemical characteristics of the soil which are compare means of two statistical populations and t-Student tests. Also, a non- parametric (chi-square test was used in order to determine the statistical analysis of the effect of non-soil factors of occurrence of digitated gullies including slope classes, altitude classes, lithology and land use. Results: Initial investigations of the field observations, aerial photos and satellite images showed that different factors play role in the occurrence of digitated gully in the study area. So, physical and chemical characteristics of the soil, slope classes, altitude classes, lithology and land use were investigated in current study. A: Results of the effective physical and chemical characteristics of the surface and sub- surface soil on the occurrence of digitated gully erosion Results

Investigation of Water Holding Capacity of Sugarcane Mulch for Sand Dune Stabilization in Ahvaz

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T. Jamili

2017-01-01

Full Text Available Introduction: Wind erosion is one of the most serious problems in southwest Iran. Fine-grained structure of sand dunes with not enough strong composition and their low moisture retention property make them susceptible to wind erosion. They lack organic matter and are considered inherently of low fertility (Ahmadi, 2002. Studies have shown that non-erodible materials which include bentonite clay (Diouf et al., 1990, ureamelamine formaldehyde and urea–formaldehyde with 0.25% sodium chloride (Lahalih and Ahmed, 1998, acids, enzymes, lignosulfonates, polymers, tree resins (Santoni et al., 2001, waterborne polymer emulsion (Al-Khanbashi and Abdalla, 2006, polyvinyl alcohol and a polyvinyl acetate emulsion (Newman et al., 2005; Han et al., 2007, ash and polyacrylamide (Yang and Zejun, 2012.have significant potential in reducing wind erosion The area under farming of sugarcane in Khuzestan, Iran, is more than 130,000, ha. Vinasse and Filter Kike are two organic ingredients of sugarcane residues which are generated as byproduct materials insugarcane processing. In recent years these residues have been released into the environment and cause it regarded as water pollutant. Over 800,000 m3 of Vinasse is annually stored in each agro-industry. Vinasse also is rich in K, Ca, and Mg with moderate amounts of P and N,and non toxic complexes or heavy metals. Filter Kike is another residue produced in huge amounts by the agro-industry that is composed of cellulosic substances, CaCO3, N, P, K, organic matter, and clay. Therefore, the objective of this research is to investigate the effect of sugarcane mulch on water holding capacity in soil. This study is performed to evaluate the feasibility of using sugarcane residues inproduce of ecofriendly mulches for environmental use. In order of achieving these goals, Vinase, Filter Cake, and clay soil from near the sand dunes were used as sugarcane mulches. Further comparison between traditional oil mulches and

Modeling erosion of unsaturated compacted bentonite by groundwater flow; pinhole erosion test case

International Nuclear Information System (INIS)

Laurila, T.; Sane, P.; Olin, M.; Koskinen, K.

2012-01-01

Document available in extended abstract form only. Erosion of compacted clay material by water flow is a critical factor affecting the performance of radioactive waste confinement. Our emphasis in this work is the buffer of KBS-3V concept, proposed to be compacted MX-80 bentonite. Unsaturated erosion occurs during the saturation phase of the EBS, and the main quantity of interest is the total buffer mass carried away by a groundwater flow that induces erosion by forming piping channels near the buffer/rock interface. The purpose of this work is to provide modeling tools to support erosion experiments. Role of modeling is first to interpret experimental observations in terms of processes, and to estimate robustness of experimental results. Secondly, we seek to scale up results from the laboratory scale, particularly to time scales longer than those experimentally accessible. We have performed modeling and data analysis pertaining to tests of unsaturated clay erosion. Pinhole experiments were used to study this erosion case. The main differences to well-understood pinhole erosion tests are that the material is strongly swelling and that the water flow is not determined by the pressure head but by the total flux. Groundwater flow in the buffer is determined by the flux because pressure losses occur overwhelmingly in the surrounding rock, not in the piping channel. We formulate a simple model that links an effective solid diffusivity -based swelling model to erosion by flow on the solid/liquid interface. The swelling model is similar in concept to that developed at KTH, but simpler. Erosion in the model is caused by laminar flow in the pinhole, and happens in a narrow region at the solid/liquid interface where velocity and solid volume fraction overlap. The erosion model can be mapped to erosion by wall shear, and can thus be considered as extension of that classic erosion model. The main quantity defining the behavior of clay erosion in the model is the ratio of

Rainfall Erosivity in Europe

DEFF Research Database (Denmark)

Panagos, Panos; Ballabio, Cristiano; Borrelli, Pasquale

2015-01-01

Rainfall is one the main drivers of soil erosion. The erosive force of rainfall is expressed as rainfall erosivity. Rainfall erosivity considers the rainfall amount and intensity, and is most commonly expressed as the Rfactor in the USLE model and its revised version, RUSLE. At national...... and continental levels, the scarce availability of data obliges soil erosion modellers to estimate this factor based on rainfall data with only low temporal resolution (daily, monthly, annual averages). The purpose of this study is to assess rainfall erosivity in Europe in the form of the RUSLE R-factor, based...

Estimating surface soil erosion losses and mapping erosion risk for Yusufeli micro-catchment (Artvin

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Mustafa Tüfekçioğlu

2016-10-01

Full Text Available Sheet erosion, one of the most important types of water erosion, takes place on the top soil as tiny soil layer movement that affects lake and stream ecosystem. This type of erosion is very important because the productive soil layer on the top soil can be lost in a very short period of time. The goal of this study was to quantify the amount of surface (sheet and rill soil erosion, and to identify areas under high erosion risk within the study area at Yusufeli province in Artvin by using RUSLE erosion methodology. As a result of the study it was found that the average annual potential soil loss by surface erosion was 3.6 ton ha-1yr-1. Additionally, the maps produced and conclusions reached by the study revealed that the areas of high erosion risk were identified spatially and measures to control erosion on some of these high risk areas can be possible with appropriate erosion control techniques.

A multiscale investigation of habitat use and within-river distribution of sympatric sand darter species

Science.gov (United States)

Thompson, Patricia A.; Welsh, Stuart A.; Strager, Michael P.; Rizzo, Austin A.

2018-01-01

The western sand darter Ammocrypta clara, and eastern sand darter Ammocrypta pellucida, are sand-dwelling fishes of conservation concern. Past research has emphasized the importance of studying individual populations of conservation concern, while recent research has revealed the importance of incorporating landscape scale processes that structure habitat mosaics and local populations. We examined habitat use and distributions of western and eastern sand darters in the lower Elk River of West Virginia. At the sandbar habitat use scale, western sand darters were detected in sandbars with greater area, higher proportions of coarse grain sand and faster bottom current velocity, while the eastern sand darter used a wider range of sandbar habitats. The landscape scale analysis revealed that contributing drainage area was an important predictor for both species, while sinuosity, which presumably represents valley type, also contributed to the western sand darter’s habitat suitability. Sandbar quality (area, grain size, and velocity) and fluvial geomorphic variables (drainage area and valley type) are likely key driving factors structuring sand darter distributions in the Elk River. This multiscale study of within-river species distribution and habitat use is unique, given that only a few sympatric populations are known of western and eastern sand darters.

Sedimentology and composition of sands injected during the seismic crisis of May 2012 (Emilia, Italy): clues for source layer identification and liquefaction regime

Science.gov (United States)

Fontana, D.; Lugli, S.; Marchetti Dori, S.; Caputo, R.; Stefani, M.

2015-07-01

In May 2012 widespread sand blows formed along buried channels in the eastern sector of the Po Plain (Northern Italy) as a consequence of a series of seismic events with main shocks of Mw 6.1 and 5.9. At San Carlo (Ferrara) a trench dug a few week after the earthquakes exposed sand dikes cutting through an old Reno River channel-levee system that was diverted in the 18th century and was deposited starting from the 14th century (unit A). This sequence overlies a Holocene muddy floodplain deposits and contains scattered sandy channel deposits (unit B) and a Pleistocene channel sand unit (unit C). Sands with inverse and normal grading, concave layering and vertical lamination coexisting along the dikes suggest multiple rhythmic opening and closing of the fractures that were injected and filled by a slurry of sand during the compression pulses, and emptied during the extension phase. The pulse mechanism may have lasted for several minutes and formed well stratified sand volcanoes structures that formed at the top of the fractures. Sands from dikes and from the various units show well defined compositional fields from lithoarenitic to quartz-feldspar-rich compositions. Sands from the old Reno levee and channel fill (unit A) have abundant lithic fragments derived from the erosion of Apennine sedimentary carbonate and terrigenous successions. Composition of the sand filling the dikes show clear affinities with sand layers of the old Reno River channel (Unit A) and clearly differ from any sand from deeper Holocene and Pleistocene layers (Unit B and C), which are richer in quartz and feldspar and poorer in sedimentary lithic fragments. Sorting related to sediment flux variations did not apparently affect the sand composition across the sedimentary structures. Textural and compositional data indicate that the liquefaction processes originated from a relatively shallow source consisting of channel sands located within Unit A at 6.8.to 7.5 m depth.

The comparison of various approach to evaluation erosion risks and design control erosion measures

Science.gov (United States)

Kapicka, Jiri

2015-04-01

In the present is in the Czech Republic one methodology how to compute and compare erosion risks. This methodology contain also method to design erosion control measures. The base of this methodology is Universal Soil Loss Equation (USLE) and their result long-term average annual rate of erosion (G). This methodology is used for landscape planners. Data and statistics from database of erosion events in the Czech Republic shows that many troubles and damages are from local episodes of erosion events. An extent of these events and theirs impact are conditional to local precipitation events, current plant phase and soil conditions. These erosion events can do troubles and damages on agriculture land, municipally property and hydro components and even in a location is from point of view long-term average annual rate of erosion in good conditions. Other way how to compute and compare erosion risks is episodes approach. In this paper is presented the compare of various approach to compute erosion risks. The comparison was computed to locality from database of erosion events on agricultural land in the Czech Republic where have been records two erosion events. The study area is a simple agriculture land without any barriers that can have high influence to water flow and soil sediment transport. The computation of erosion risks (for all methodology) was based on laboratory analysis of soil samples which was sampled on study area. Results of the methodology USLE, MUSLE and results from mathematical model Erosion 3D have been compared. Variances of the results in space distribution of the places with highest soil erosion where compared and discussed. Other part presents variances of design control erosion measures where their design was done on based different methodology. The results shows variance of computed erosion risks which was done by different methodology. These variances can start discussion about different approach how compute and evaluate erosion risks in areas

Modelling soil erosion and associated sediment yield for small headwater catchments of the Daugava spillway valley, Latvia

Science.gov (United States)

Soms, Juris

2015-04-01

The accelerated soil erosion by water and associated fine sediment transfer in river catchments has various negative environmental as well as economic implications in many EU countries. Hence, the scientific community had recognized and ranked soil erosion among other environmental problems. Moreover, these matters might worsen in the near future in the countries of the Baltic Region, e.g. Latvia considering the predicted climate changes - more precisely, the increase in precipitation and shortening of return periods of extreme rainfall events, which in their turn will enable formation of surface runoff, erosion and increase of sediment delivery to receiving streams. Thereby it is essential to carry out studies focused on these issues in order to obtain reliable data in terms of both scientific and applied aims, e.g. environmental protection and sustainable management of soils as well as water resources. During the past decades, many of such studies of soil erosion had focused on the application of modelling techniques implemented in a GIS environment, allowing indirectly to estimate the potential soil losses and to quantify related sediment yield. According to research results published in the scientific literature, this approach currently is widely used all over the world, and most of these studies are based on the USLE model and its revised and modified versions. Considering that, the aim of this research was to estimate soil erosion rates and sediment transport under different hydro-climatic conditions in south-eastern Latvia by application of GIS-based modelling. For research purposes, empirical RUSLE model and ArcGIS software were applied, and five headwater catchments were chosen as model territories. The selected catchments with different land use are located in the Daugava spillway valley, which belongs to the upper Daugava River drainage basin. Considering lithological diversity of Quaternary deposits, a variety of soils can be identified, i.e., Stagnic

Investigation of the Degradation Mechanisms of Particulate Reinforced Epoxy Coatings and Zinc-Rich Coatings Under an Erosion and Corrosion Environment for Oil and Gas Industry Applications

Science.gov (United States)

Wang, Dailin

During oil and gas production and transportation, the presence of an oil-sand slurry, together with the presence of CO2, H2S, oxygen, and seawater, create an erosive/abrasive and corrosive environment for the interior surfaces of undersea pipelines transporting oil and gas from offshore platforms. Erosion/wear and corrosion are often synergic processes leading to a much greater material loss of pipeline cross-section than that caused by each individual process alone. Both organic coatings and metallic sacrificial coatings have been widely employed to provide protection to the pipeline steels against corrosion through barrier protection and cathodic protection, and these protection mechanisms have been well studied. However, coating performance under the synergic processes of erosion/wear and corrosion have been much less researched and coating degradation mechanisms when erosion/wear and corrosion are both going on has not been well elucidated. In the work presented in this dissertation, steel panels coated with filler reinforced epoxy coatings and carbon nanotubes (CNTs) reinforced zinc-rich coatings have been evaluated under erosion/wear followed by an exposure to a corrosive environment. Electrochemical tests and material characterization methods have been applied to study the degradation mechanisms of the coatings during the tests and coating degradation mechanisms have been proposed. While organic coatings with a lower amount of filler particles provided better protection in a corrosive environment alone and in solid particle impingement erosion testing alone, organic coatings with a higher amount of filler particles showed better performance during wear testing alone. A higher amount of filler particles was also beneficial in providing protection against wear and corrosion environment, and erosion and corrosion environment. Coating thickness played a significant role in the barrier properties of the coatings under both erosion and corrosion tests. When the

MECHANICAL REGENERATION OF SAND WASTE

Directory of Open Access Journals (Sweden)

D. I. Gnir

2005-01-01

Full Text Available The experimental activation of the sand regenerator of the firm SINTO is carried out at ОАО “MZOO". It is shown that sand grains are cleared from films of binding agents, that allows to use the treated sand for preparation of agglutinant and core sands.

Booming Sand Dunes

Science.gov (United States)

Vriend, Nathalie

"Booming" sand dunes are able to produce low-frequency sound that resembles a pure note from a music instrument. The sound has a dominant audible frequency (70-105 Hz) and several higher harmonics and may be heard from far distances away. A natural or induced avalanche from a slip face of the booming dune triggers the emission that may last for several minutes. There are various references in travel literature to the phenomenon, but to date no scientific explanation covered all field observations. This thesis introduces a new physical model that describes the phenomenon of booming dunes. The waveguide model explains the selection of the booming frequency and the amplification of the sound in terms of constructive interference in a confined geometry. The frequency of the booming is a direct function of the dimensions and velocities in the waveguide. The higher harmonics are related to the higher modes of propagation in the waveguide. The experimental validation includes quantitative field research at the booming dunes of the Mojave Desert and Death Valley National Park. Microphone and geophone recordings of the acoustic and seismic emission show a variation of booming frequency in space and time. The analysis of the sensor data quantifies wave propagation characteristics such as speed, dispersion, and nonlinear effects and allows the distinction between the source mechanism of the booming and the booming itself. The migration of sand dunes results from a complicated interplay between dune building, wind regime, and precipitation. The morphological and morphodynamical characteristics of two field locations are analyzed with various geophysical techniques. Ground-penetrating radar images the subsurface structure of the dunes and reveal a natural, internal layering that is directly related to the history of dune migration. The seismic velocity increases abruptly with depth and gradually increases with downhill position due to compaction. Sand sampling shows local

Environmental Quality News: Measuring the Sands.

Science.gov (United States)

Willson, Sally Dana

1981-01-01

Describes a study by high school students and university researchers of coastal erosion along the beaches of a Long Island, New York town. Data will be used in making decisions regarding coastal zoning, planning, and management. (Author/WB)

Improving the geotechnical behavior of sand through cohesive admixtures

Directory of Open Access Journals (Sweden)

Mohie eldin Mohamed Afify Elmashad

2018-04-01

Full Text Available Irrigation projects in Egypt have been facing tremendous challenges, mostly is the scarcity of irrigation water. The current research presents the effect of different cohesive admixture on the conductivity of siliceous sand in general and its other geotechnical properties. Two different types of conventional swelling clay from (Toshka, 6th of October as well as bentonite were used to construct the irrigation canals and embankment. The results indicated that increase in the plasticity properties of the treated soil also decrease the permeability and infiltration. Moreover, the dry density of 2.08 t/m3 was obtained from sand and 20% 6th of October mixture, also the CBR of 31.20% were obtained from sand and 8% 6th of October mixture. Increasing the bentonite ratio increases the cohesion and decreasing the permeability. The swelling ratios of sand 6th of October Clay mixture is equal to 0.28%, and the fictitious stress at which the swelling ratio is nil, is equal to 16 kPa. Keywords: Sand, Swelling clay, Bentonite, Compaction test, Consolidation test, Triaxial test

Crushed rock sand – An economical and ecological alternative to natural sand to optimize concrete mix

Directory of Open Access Journals (Sweden)

Sanjay Mundra

2016-09-01

Full Text Available The study investigates the use of crushed rock sand as viable alternative to Natural River sand that is being conventionally used as fine aggregate in cement concrete. Various mix designs were developed for different grades of concrete based on IS, ACI and British codes using Natural River sand and crushed rock sand. In each case, the cube compressive strength test, and beam flexure tests were conducted. The results of the study show that, the strength properties of concrete using crushed rock sand are nearly similar to the conventional concrete. The study has shown that crushed stone sand can be used as economic and readily available alternative to river sand and can therefore help to arrest the detrimental effects on the environment caused due to excessive mining of river sand.

The development of U. S. soil erosion prediction and modeling

Directory of Open Access Journals (Sweden)

John M. Laflen

2013-09-01

Full Text Available Soil erosion prediction technology began over 70 years ago when Austin Zingg published a relationship between soil erosion (by water and land slope and length, followed shortly by a relationship by Dwight Smith that expanded this equation to include conservation practices. But, it was nearly 20 years before this work's expansion resulted in the Universal Soil Loss Equation (USLE, perhaps the foremost achievement in soil erosion prediction in the last century. The USLE has increased in application and complexity, and its usefulness and limitations have led to the development of additional technologies and new science in soil erosion research and prediction. Main among these new technologies is the Water Erosion Prediction Project (WEPP model, which has helped to overcome many of the shortcomings of the USLE, and increased the scale over which erosion by water can be predicted. Areas of application of erosion prediction include almost all land types: urban, rural, cropland, forests, rangeland, and construction sites. Specialty applications of WEPP include prediction of radioactive material movement with soils at a superfund cleanup site, and near real-time daily estimation of soil erosion for the entire state of Iowa.

Differential erosion and the formation of layered yardangs in the Loulan region (Lop Nur), eastern Tarim Basin

Science.gov (United States)

Lin, Yongchong; Xu, Lishuai; Mu, Guijin

2018-02-01

Yardangs are a type of wind-sculpted landform which generally form in hyper-arid regions. Several factors affect the development of yardangs, and the relative importance of these factors likely varies with differences in regional environmental factors. In the Loulan region of Lop Nur, wind dynamics are the principal factor affecting the development of yardangs. However, layered yardangs, which have undergone a unique form of differential erosion, are common in the region. These erosional landforms differ from typical yardangs which are eroded solely by abrasion and deflation. We conducted field and laboratory investigations of layered yardangs to determine their origin. The results indicate that there are two types of strata comprising the yardangs: uncompacted sand-silt layers, with a lower carbonate content; and compacted clay-silt layers, with a higher carbonate content. Both types of strata are horizontal and occur in alternating layers. This type of structure enables the wind to more easily erode the less resistant sand-silt layers at different heights, leaving the more resistant compacted clay-silt layers relatively intact. Eventually the undercut remnant clay-silt layers collapse once the weight of the suspended strata exceeds their elastic resistance (more than 90% of the fallen blocks have length/thickness ratios between 1.2 and 2.5). Therefore, in addition to wind dynamics, the lithology and structure of the strata are important factors affecting the development of the layered yardangs. This type of differential erosion accelerates the development of the yardangs in the Loulan region.

Predicting of soil erosion with regarding to rainfall erosivity and soil erodibility

Science.gov (United States)

Suif, Zuliziana; Razak, Mohd Amirun Anis Ab; Ahmad, Nordila

2018-02-01

The soil along the hill and slope are wearing away due to erosion and it can take place due to occurrence of weak and heavy rainfall. The aim of this study is to predict the soil erosion degree in Universiti Pertahanan Nasional Malaysia (UPNM) area focused on two major factor which is soil erodibility and rainfall erosivity. Soil erodibility is the possibilities of soil to detach and carried away during rainfall and runoff. The "ROM" scale was used in this study to determine the degree of soil erodibility, namely low, moderate, high, and very high. As for rainfall erosivity, the erosive power caused by rainfall that cause soil loss. A daily rainfall data collected from January to April was analyzed by using ROSE index classification to identify the potential risk of soil erosion. The result shows that the soil erodibilty are moderate at MTD`s hill, high at behind of block Lestari and Landslide MTD hill, and critical at behind the mess cadet. While, the highest rainfall erosivity was recorded in March and April. Overall, this study would benefit the organization greatly in saving cost in landslide protection as relevant authorities can take early measures repairing the most affected area of soil erosion.

Mesh erosion after abdominal sacrocolpopexy.

Science.gov (United States)

Kohli, N; Walsh, P M; Roat, T W; Karram, M M

1998-12-01

To report our experience with erosion of permanent suture or mesh material after abdominal sacrocolpopexy. A retrospective chart review was performed to identify patients who underwent sacrocolpopexy by the same surgeon over 8 years. Demographic data, operative notes, hospital records, and office charts were reviewed after sacrocolpopexy. Patients with erosion of either suture or mesh were treated initially with conservative therapy followed by surgical intervention as required. Fifty-seven patients underwent sacrocolpopexy using synthetic mesh during the study period. The mean (range) postoperative follow-up was 19.9 (1.3-50) months. Seven patients (12%) had erosions after abdominal sacrocolpopexy with two suture erosions and five mesh erosions. Patients with suture erosion were asymptomatic compared with patients with mesh erosion, who presented with vaginal bleeding or discharge. The mean (+/-standard deviation) time to erosion was 14.0+/-7.7 (range 4-24) months. Both patients with suture erosion were treated conservatively with estrogen cream. All five patients with mesh erosion required transvaginal removal of the mesh. Mesh erosion can follow abdominal sacrocolpopexy over a long time, and usually presents as vaginal bleeding or discharge. Although patients with suture erosion can be managed successfully with conservative treatment, patients with mesh erosion require surgical intervention. Transvaginal removal of the mesh with vaginal advancement appears to be an effective treatment in patients failing conservative management.

Susceptibility of bovine dental enamel with initial erosion lesion to new erosive challenges.

Science.gov (United States)

Oliveira, Gabriela Cristina de; Tereza, Guida Paola Genovez; Boteon, Ana Paula; Ferrairo, Brunna Mota; Gonçalves, Priscilla Santana Pinto; Silva, Thiago Cruvinel da; Honório, Heitor Marques; Rios, Daniela

2017-01-01

This in vitro study evaluated the impact of initial erosion on the susceptibility of enamel to further erosive challenge. Thirty bovine enamel blocks were selected by surface hardness and randomized into two groups (n = 15): GC- group composed by enamel blocks without erosion lesion and GT- group composed by enamel blocks with initial erosion lesion. The baseline profile of each block was determined using the profilometer. The initial erosion was produced by immersing the blocks into HCl 0.01 M, pH 2.3 for 30 seconds, under stirring. The erosive cycling consisted of blocks immersion in hydrochloric acid (0.01 M, pH 2.3) for 2 minutes, followed by immersion in artificial saliva for 120 minutes. This procedure was repeated 4 times a day for 5 days, and the blocks were kept in artificial saliva overnight. After erosive cycling, final profile measurement was performed. Profilometry measured the enamel loss by the superposition of initial and final profiles. Data were analyzed by t-test (perosion on bovine dental enamel does not enhance its susceptibility to new erosive challenges.

Rheological Characterization of Green Sand Flow

DEFF Research Database (Denmark)

Jabbaribehnam, Mirmasoud; Spangenberg, Jon; Hovad, Emil

2016-01-01

The main aim of this paper is to characterize experimentally the flow behaviour of the green sand that is used for casting of sand moulds. After the sand casting process is performed, the sand moulds are used for metal castings. The rheological properties of the green sand is important to quantif...

Effects of traditional land transactions on soil erosion and land degradation

OpenAIRE

Leduka, R.C.

1998-01-01

A research report on the effects of traditional land transactions on soil erosion and land degradation in Lesotho. This report focuses on the land transactions in Lesotho and how these transaction affect the growing erosion rates of the soil.

Developing an Erosion Rate Map for Myanmar Using USLE, GIS and Remote Sensing

Science.gov (United States)

Emtehani, Sobhan; Rutten, Martine

2017-04-01

Predicting erosion and estimating sediment loads in rivers are of major tasks in water resources system planning and management. In Myanmar erosion and collapse of river banks is common during the rainy season and riverine communities are frequently forced to relocate as their homes are dangerously close to the disintegrating river banks (Mann 2013). Myanmar is one of climatically most diverse countries located in Southeast Asia, where sheet, rill, and gully erosion affect crop yields as well as livelihood strategies of many people (Htwe, Brinkmann et al. 2015). In Myanmar, soil erosion measurement and monitoring approaches are increasingly important for land management planning to effectively avoid erosion and soil degradation, but such monitoring is limited by the availability of data and budgetary constraints. Therefore, spatial modeling approaches using GIS and remote sensing techniques play an important role for rapid risk assessments (Htwe 2016). In this study ''Model Builder'' tool in ArcGIS was used to create a model which generates an erosion rate map using Universal Soil Loss Equation (USLE). USLE is the product of five factors: rainfall erosivity factor (R), soil erodibility factor (K), slope length and steepness factor (LS), crop management factor (C), and support practice factor (P). Input data files for this model were acquired from online open source databases. Precipitation data was downloaded from Tropical Rainfall Measuring Mission (TRMM) for calculation of R factor. The resolution of TRMM data is very coarse (0.25 degree × 0.25 degree), therefore it was spatially downscaled by developing a relation between TRMM and Normalized Difference Vegetation Index (NDVI) using regression analysis method. Soil maps depicting percentages of sand, clay and silt were obtained from soilgrids website for calculation of K factor. Digital Elevation Model (DEM) with resolution of 90 meters was taken from Shuttle Radar Topography Mission (SRTM) for calculation of LS

A Life Cycle Assessment of Silica Sand: Comparing the Beneficiation Processes

Directory of Open Access Journals (Sweden)

Anamarija Grbeš

2015-12-01

Full Text Available Silica sand or quartz sand is a mineral resource with a wide variety of application; glass industry, construction and foundry are the most common examples thereof. The Republic of Croatia has reserves of 40 million tons of silica sand and a long tradition of surface mining and processing. The average annual production of raw silica sand in Croatia in the period from 2006 to 2011 amounted to 150 thousand tons. This paper presents cradle to gate LCA results of three different types of beneficiation techniques: electrostatic separation; flotation; gravity concentration. The aim of this research is to identify and quantify the environmental impacts of the silica sand production, to learn the range of the impacts for different processing methods, as well as to identify the major contributors and focus for further process design development.

Susceptibility of bovine dental enamel with initial erosion lesion to new erosive challenges.

Directory of Open Access Journals (Sweden)

Gabriela Cristina de Oliveira

Full Text Available This in vitro study evaluated the impact of initial erosion on the susceptibility of enamel to further erosive challenge. Thirty bovine enamel blocks were selected by surface hardness and randomized into two groups (n = 15: GC- group composed by enamel blocks without erosion lesion and GT- group composed by enamel blocks with initial erosion lesion. The baseline profile of each block was determined using the profilometer. The initial erosion was produced by immersing the blocks into HCl 0.01 M, pH 2.3 for 30 seconds, under stirring. The erosive cycling consisted of blocks immersion in hydrochloric acid (0.01 M, pH 2.3 for 2 minutes, followed by immersion in artificial saliva for 120 minutes. This procedure was repeated 4 times a day for 5 days, and the blocks were kept in artificial saliva overnight. After erosive cycling, final profile measurement was performed. Profilometry measured the enamel loss by the superposition of initial and final profiles. Data were analyzed by t-test (p<0.05. The result showed no statistically significant difference between groups (GS = 14.60±2.86 and GE = .14.69±2.21 μm. The presence of initial erosion on bovine dental enamel does not enhance its susceptibility to new erosive challenges.

Parametric Study of Slurry-Erosion of Hydroturbine Steels with and without Detonation Gun Spray Coatings using Taguchi Technique

Science.gov (United States)

Grewal, Harpreet Singh; Bhandari, Sanjeev; Singh, Harpreet

2012-09-01

WC-Co-Cr coatings were deposited on some hydroturbine 13Cr4Ni and 16Cr5Ni steels by the detonation-gun spray process. An in-depth characterization of the as-sprayed coating was done using X-ray diffraction (XRD) and scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy (EDS) techniques. Microhardness and porosity measurements were also made. The coating was found to have a typical splat-like morphology with some indications of unmelted carbide particles. The XRD results showed the presence of WC as the primary phase along with W2C and Co6W6C as secondary phases. Furthermore, the slurry erosion behavior of the coatings was investigated to ascertain the usefulness of the coatings to reduce the slurry erosion of the steels. The effect of four operating factors viz. the velocity, impact angle, concentration, and particle size on the slurry erosion of coated and bare steels has been studied using a high-speed jet-type test rig. The sand used as an erodent was collected from a power plant to replicate the actual turbine conditions. It has been observed that the given cermet coating can enhance the erosion resistance of the steel. Velocity was found to be the most significant factor affecting the erosion behavior of the coating, whereas it was the erodent particle size in the case of uncoated steel. As evidenced from the SEM images, the platelet mechanism of erosion seemed to be the prominent one, causing the removal of material from the surface of the steel, whereas for the coating, the formation and interlinking of cracks resulted in the removal of material.

Analysis of Physical Properties and Mineralogical of Pyrolysis Tires Rubber Ash Compared Natural Sand in Concrete material

Science.gov (United States)

Syamir Senin, Mohamad; Shahidan, Shahiron; Syazani Leman, Alif; Izzati Raihan Ramzi Hannan, Nurul

2016-11-01

Waste tires pose significant health and environmental concerns if not recycled or discarded properly. At the same time, natural sand is becoming scarcer and costlier due to its non-availability. Waste tires as fine aggregate can be an economical and sustainable alternative to the natural sand. Recent years, the interest on recycling waste tires into civil engineering applications by the researchers has increased. In this research, the chemical and physical properties of the tires rubber ash and the natural sand have been analysed. The densities of the rubber ash are lower than the natural sand. Rubber ash had finer particle size compared to the natural sand. Almost all chemical in the natural sand had in rubber ash with the additional sulphur trioxide and zinc oxide in the rubber ash, made the rubber ash better than natural sand. Rubber ash seems to be a suitable material to use in concrete as sand replacement.

Publication trends in aeolian research: An analysis of the Bibliography of Aeolian Research

Science.gov (United States)

Stout, John E.; Warren, Andrew; Gill, Thomas E.

2009-04-01

An analysis of the Bibliography of Aeolian Research has provided information regarding publication trends in aeolian research. Results suggest that there has been a significant increase in the number of publications per year since the first aeolian-research publication appeared in 1646. Rates of publication have increased from only three publications in the 17th Century to nearly three publications per day in the 21st Century. The temporal distribution of publications follows a complex pattern that is influenced by many factors. In the 17th and 18th Centuries, publications appear as isolated clusters indicating limited interest in aeolian research and limited opportunities for individuals to contribute to scientific literature. With time, many new scientific societies are formed and many new scientific journals are established, opening new opportunities for scientists to contribute to scientific discourse. Landmark publications open up new research areas and define new directions for aeolian research. General advances in science and technology provide new techniques for sampling blowing sand and dust. In addition, clear signs exist that publication rates respond to major environmental and climatic events, especially large-scale disasters that focus attention on wind erosion and blowing dust. The Sirocco dust events of 1901-1903, the North American Dust Bowl of the1930s, and the recent sand and dust storm problems in China have all led to significant increases in the number of publications in aeolian research. Rates of publication are negatively influenced by major political and social upheavals, especially global conflicts such as World Wars I and II. Sudden shifts in government structure and support can also influence publication rates. A good example is the increased publication rates in China following the end of the Cultural Revolution, a trend that continues today.

Advanced experimental and numerical techniques for cavitation erosion prediction

CERN Document Server

Chahine, Georges; Franc, Jean-Pierre; Karimi, Ayat

2014-01-01

This book provides a comprehensive treatment of the cavitation erosion phenomenon and state-of-the-art research in the field. It is divided into two parts. Part 1 consists of seven chapters, offering a wide range of computational and experimental approaches to cavitation erosion. It includes a general introduction to cavitation and cavitation erosion, a detailed description of facilities and measurement techniques commonly used in cavitation erosion studies, an extensive presentation of various stages of cavitation damage (including incubation and mass loss), and insights into the contribution of computational methods to the analysis of both fluid and material behavior. The proposed approach is based on a detailed description of impact loads generated by collapsing cavitation bubbles and a physical analysis of the material response to these loads. Part 2 is devoted to a selection of nine papers presented at the International Workshop on Advanced Experimental and Numerical Techniques for Cavitation Erosion (Gr...

Low cost sic coated erosion resistant graphite

International Nuclear Information System (INIS)

Zafar, M.F.; Nicholls, J.R.

2007-01-01

The development of materials with unique and improved properties using low cost processes is essential to increase performance and reduce cost of the solid rocket motors. Specifically advancements are needed for boost phase nozzle. As these motors operate at very high pressure and temperatures, the nozzle must survive high thermal stresses with minimal erosion to maintain performance. Currently three material choices are being exploited; which are refractory metals, graphite and carbon-carbon composites. Of these three materials graphite is the most attractive choice because of its low cost, light weight, and easy forming. However graphite is prone to erosion, both chemical and mechanical, which may affect the ballistic conditions and mechanical properties of the nozzle. To minimize this erosion high density graphite is usually preferred; which is again very expensive. Another technique used to minimize the erosion is Pyrolytic Graphite (PG) coating inside the nozzle. However PG coating is prone to cracking and spallation along with very cumbersome deposition process. Another possible methodology to avoid this erosion is to convert the inside surface of the rocket nozzle to Silicon Carbide (SiC), which is very erosion resistant and have much better thermal stability compared to graphite and even PG. Due to its functionally gradient nature such a layer will be very adherent and resistant to spallation. The current research is focused on synthesizing, characterizing and oxidation testing of such a converted SiC layer on commercial grade graphite. (author)

Field observation of morpho-dynamic processes during storms at a Pacific beach, Japan: role of long-period waves in storm-induced berm erosion.

Science.gov (United States)

Mizuguchi, Masaru; Seki, Katsumi

2015-01-01

Many ultrasonic wave gages were placed with a small spacing across the swash zone to monitor either sand level or water level. Continuous monitoring conducted for a few years enabled the collection of data on the change in wave properties as well as swash-zone profiles. Data sets including two cases of large-scale berm erosion were analyzed. The results showed that 1) shoreline erosion started when high waves with significant power in long-period (1 to 2 min.) waves reached the top of a well-developed berm with the help of rising tide; 2) the beach in the swash zone was eroded with higher elevation being more depressed, while the bottom elevation just outside the swash zone remained almost unchanged; and 3) erosion stopped in a few hours after the berm was completely eroded or the swash-zone slope became uniformly mild. These findings strongly suggest that long waves play a dominant role in the swash-zone dynamics associated with these erosional events.

Soil Erosion Estimation Using Remote Sensing Techniques in Wadi Yalamlam Basin, Saudi Arabia

Directory of Open Access Journals (Sweden)

Jarbou A. Bahrawi

2016-01-01

Full Text Available Soil erosion is one of the major environmental problems in terms of soil degradation in Saudi Arabia. Soil erosion leads to significant on- and off-site impacts such as significant decrease in the productive capacity of the land and sedimentation. The key aspects influencing the quantity of soil erosion mainly rely on the vegetation cover, topography, soil type, and climate. This research studies the quantification of soil erosion under different levels of data availability in Wadi Yalamlam. Remote Sensing (RS and Geographic Information Systems (GIS techniques have been implemented for the assessment of the data, applying the Revised Universal Soil Loss Equation (RUSLE for the calculation of the risk of erosion. Thirty-four soil samples were randomly selected for the calculation of the erodibility factor, based on calculating the K-factor values derived from soil property surfaces after interpolating soil sampling points. Soil erosion risk map was reclassified into five erosion risk classes and 19.3% of the Wadi Yalamlam is under very severe risk (37,740 ha. GIS and RS proved to be powerful instruments for mapping soil erosion risk, providing sufficient tools for the analytical part of this research. The mapping results certified the role of RUSLE as a decision support tool.

Polymers Erosion and Contamination Experiment Being Developed

Science.gov (United States)

deGroh, Kim K.; Banks, Bruce A.; Barney-Barton, Elyse A.; Sechkar, Edward; Hunt, Patricia

1999-01-01

The Polymers Erosion and Contamination Experiment (PEACE) is currently being developed at the NASA Lewis Research Center by the Electro-Physics Branch in conjunction with students and faculty from Hathaway Brown School in Cleveland. The experiment is a Get Away Special Canister shuttle flight experiment sponsored by the American Chemical Society. The two goals of this experiment are (1) to measure ram atomic oxygen erosion rates of approximately 40 polymers that have potential use in space applications and (2) to validate a method for identifying sources of silicone contamination that occur in the shuttle bay. Equipment to be used in this flight experiment is shown in the schematic diagram. Spacecraft materials subjected to attack by atomic oxygen in the space environment experience significant degradation over the span of a typical mission. Therefore, learning the rates of atomic oxygen erosion of a wide variety of polymers would be of great benefit to future missions. PEACE will use two independent techniques to determine the atomic oxygen erosion rates of polymers. Large (1-in.-diameter) samples will be used for obtaining mass loss. Preflight and postflight dehydrated masses will be obtained, and the mass lost during flight will be determined. Small (0.5-in.-diameter) samples will be protected with isolated particles (such as NaCl crystals) and then exposed to the space environment. After flight, the protective particles will be removed (washed off) and atomic force microscopy (AFM) will be used to measure the erosion depth from protected mesas. Erosion depth measurements are more sensitive than traditional mass measurements and are very useful for materials with low erosion yields or with very low fluence missions.

Protection from erosion following wildfire

Science.gov (United States)

Peter R. Robichaud; William J. Elliot

2006-01-01

Erosion in the first year after a wildfire can be up to three orders of magnitude greater than the erosion from undisturbed forests. To mitigate potential postfire erosion, various erosion control treatments are applied on highly erodible areas with downstream resources in need of protection. Because postfire erosion rates generally decline by an order of magnitude for...

Sand Particles Impact on the Tribological Behavior of Sliding Contact

Directory of Open Access Journals (Sweden)

Aldajah Saud

2016-01-01

Full Text Available Lubricant contaminants cause severe problems to machines. Substantial research has been conducted to study the impact of such contaminates on the tribological performance of lubricated contacts. The primary goal of such studies is to find solutions to avoid the dirtiest cause of damaging machines’ parts and to reduce energy consumption and maintenance costs. The current study investigates the tribological behavior of contaminated lubricated contacts; the contaminants considered in this research are sand particles. The effect of the sand particles concentration levels on friction and wear of a tribological system under sliding contact was studied. Three different concentration levels were tested; 5%, 10% and 15%.The experimental program was carried out using an in-house built ball on disc machine at room temperature, constant normal load, constant speed, constant running time and constant travelling distance. Results showed that both friction coefficient and wear volume of the contacting surfaces are dependent on the concentration level of the sand particles. Both friction coefficient and wear volume increased by increasing the sand particles concentration. SEM was utilized to study the wear mechanisms of the contacting surfaces, it was found that the dominant wear mechanism in all cases was abrasive wear.

Improved Soil Erosion and Sediment Transport in GSSHA

Science.gov (United States)

2010-08-01

the USLE soil erodibility factor (0-1), soil cropping factor (0-1) and conservation factor (0-1) in the development by Julien (1995). The use of one...factor K represents a departure from Julien (1995), who used all three factors from the Universal Soil Loss Equation ( USLE ). This departure is justi...runoff using a research-quality data set. BACKGROUND: GSSHA simulates overland soil erosion and outputs erosion and deposition for any size class of

The Karakum and Kyzylkum sand seas dynamics; mapping and palaeoclimatic interpretations

Science.gov (United States)

Maman, Shimrit; Blumberg, Dan G.; Tsoar, Haim; Porat, Naomi

2015-04-01

Sand seas are large basins in deserts that are mantled by wind-swept sand and that exhibit varying degrees of vegetation cover. Wilson (1973) was the first to globally map and classify sand seas. Beyond Wilson's maps, however, little research has been published regarding the Karakum and Kyzylkum sand seas of Central Asia. Wilson's maps delineate active ergs from inactive ergs based solely on precipitation. His assumption of annual average rainfall as a factor determining mobility vs. stability of sand seas is too simplistic and does not take into consideration other factors such as biogenic soil crusts and wind power, both of which are known to have major effects on the dynamics of sand dunes. Literature related to mapping and classifying the Central Asian ergs by remote sensing or sand sea classification state (stable/active) is lacking. Moreover, the palaeoclimatic significance of dunes in Central Asia is difficult to assess, as there has been few studies of dune stratigraphy and numerical ages are lacking. Optically stimulated luminescence (OSL) is a firm optical dating method that is used to determine the elapsed time since quartz grains were last exposed to sunlight, thus, their burial. Yet, absolute ages indicating mobilization and stabilization of these sands, are still inadequately known and are here under discussion. The broad concern of this research was to determine the dynamics of the Central Asian sand seas and study the palaeoclimatic changes that brought to their stabilization. As there are no reliable maps or aeolian discussion of these sands, establishment of a digital data base was initially conducted, focusing on identifying and mapping these sand seas. The vast area and inaccessibility make traditional mapping methods virtually impossible. A variety of space-borne imagery both optical and radar, with varying spectral and spatial resolutions was used. These images provided the basis for mapping sand distribution, dune forms, and vegetation cover

Erosion of an ancient mountain range, the Great Smoky Mountains, North Carolina and Tennessee

Science.gov (United States)

Matmon, A.; Bierman, P.R.; Larsen, J.; Southworth, S.; Pavich, M.; Finkel, R.; Caffee, M.

2003-01-01

Analysis of 10Be and 26Al in bedrock (n=10), colluvium (n=5 including grain size splits), and alluvial sediments (n=59 including grain size splits), coupled with field observations and GIS analysis, suggest that erosion rates in the Great Smoky Mountains are controlled by subsurface bedrock erosion and diffusive slope processes. The results indicate rapid alluvial transport, minimal alluvial storage, and suggest that most of the cosmogenic nuclide inventory in sediments is accumulated while they are eroding from bedrock and traveling down hill slopes. Spatially homogeneous erosion rates of 25 - 30 mm Ky-1 are calculated throughout the Great Smoky Mountains using measured concentrations of cosmogenic 10Be and 26Al in quartz separated from alluvial sediment. 10Be and 26Al concentrations in sediments collected from headwater tributaries that have no upstream samples (n=18) are consistent with an average erosion rate of 28 ?? 8 mm Ky-1, similar to that of the outlet rivers (n=16, 24 ?? 6 mm Ky-1), which carry most of the sediment out of the mountain range. Grain-size-specific analysis of 6 alluvial sediment samples shows higher nuclide concentrations in smaller grain sizes than in larger ones. The difference in concentrations arises from the large elevation distribution of the source of the smaller grains compared with the narrow and relatively low source elevation of the large grains. Large sandstone clasts disaggregate into sand-size grains rapidly during weathering and downslope transport; thus, only clasts from the lower parts of slopes reach the streams. 26Al/10Be ratios do not suggest significant burial periods for our samples. However, alluvial samples have lower 26Al/10Be ratios than bedrock and colluvial samples, a trend consistent with a longer integrated cosmic ray exposure history that includes periods of burial during down-slope transport. The results confirm some of the basic ideas embedded in Davis' geographic cycle model, such as the reduction of relief

Erosivity, surface runoff, and soil erosion estimation using GIS-coupled runoff-erosion model in the Mamuaba catchment, Brazil.

Science.gov (United States)

Marques da Silva, Richarde; Guimarães Santos, Celso Augusto; Carneiro de Lima Silva, Valeriano; Pereira e Silva, Leonardo

2013-11-01

This study evaluates erosivity, surface runoff generation, and soil erosion rates for Mamuaba catchment, sub-catchment of Gramame River basin (Brazil) by using the ArcView Soil and Water Assessment Tool (AvSWAT) model. Calibration and validation of the model was performed on monthly basis, and it could simulate surface runoff and soil erosion to a good level of accuracy. Daily rainfall data between 1969 and 1989 from six rain gauges were used, and the monthly rainfall erosivity of each station was computed for all the studied years. In order to evaluate the calibration and validation of the model, monthly runoff data between January 1978 and April 1982 from one runoff gauge were used as well. The estimated soil loss rates were also realistic when compared to what can be observed in the field and to results from previous studies around of catchment. The long-term average soil loss was estimated at 9.4 t ha(-1) year(-1); most of the area of the catchment (60%) was predicted to suffer from a low- to moderate-erosion risk (soil erosion was estimated to exceed > 12 t ha(-1) year(-1). Expectedly, estimated soil loss was significantly correlated with measured rainfall and simulated surface runoff. Based on the estimated soil loss rates, the catchment was divided into four priority categories (low, moderate, high and very high) for conservation intervention. The study demonstrates that the AvSWAT model provides a useful tool for soil erosion assessment from catchments and facilitates the planning for a sustainable land management in northeastern Brazil.

Slurry Erosion Behavior of F6NM Stainless Steel and High-Velocity Oxygen Fuel-Sprayed WC-10Co-4Cr Coating

Science.gov (United States)

Cui, S. Y.; Miao, Q.; Liang, W. P.; Huang, B. Z.; Ding, Z.; Chen, B. W.

2017-02-01

WC-10Co-4Cr coating was applied to the surface of F6NM stainless steel by high-velocity oxygen-fuel spraying. The slurry erosion behavior of the matrix and coating was examined at different rotational speeds using a self-made machine. This experiment effectively simulates real slurry erosion in an environment with high silt load. At low velocity (<6 m/s), the main failure mechanism was cavitation. Small bubbles acted as an air cushion, obstructing direct contact between sand and the matrix surface. However, at velocity above 9 m/s, abrasive wear was the dominant failure mechanism. The results indicate that WC-10Co-4Cr coating significantly improved the slurry resistance at higher velocity, because it created a thin and dense WC coating on the surface.

Chloride ion erosion experiment research in cracked concrete

Science.gov (United States)

Ting, Shu; Yang, Li

2017-08-01

For the study of chloride ion erosion in cracked concrete, this essay tries to take advantages of relevant trails to build up concrete chloride ion diffusion model based on the Fick’s second law. The parameter of this model is easy to be set, and many factors such as the effect of cracks are taken into consideration in this experiment. The concept of “chloride ion diffusion coefficient of equivalent apparent” is introduced to simplify the calculation. It can help simplify the calculation process, and get a more accurate test result, as well as facilitating the practical application of this parameter.

Compressive behavior of fine sand.

Energy Technology Data Exchange (ETDEWEB)

Martin, Bradley E. (Air Force Research Laboratory, Eglin, FL); Kabir, Md. E. (Purdue University, West Lafayette, IN); Song, Bo; Chen, Wayne (Purdue University, West Lafayette, IN)

2010-04-01

The compressive mechanical response of fine sand is experimentally investigated. The strain rate, initial density, stress state, and moisture level are systematically varied. A Kolsky bar was modified to obtain uniaxial and triaxial compressive response at high strain rates. A controlled loading pulse allows the specimen to acquire stress equilibrium and constant strain-rates. The results show that the compressive response of the fine sand is not sensitive to strain rate under the loading conditions in this study, but significantly dependent on the moisture content, initial density and lateral confinement. Partially saturated sand is more compliant than dry sand. Similar trends were reported in the quasi-static regime for experiments conducted at comparable specimen conditions. The sand becomes stiffer as initial density and/or confinement pressure increases. The sand particle size become smaller after hydrostatic pressure and further smaller after dynamic axial loading.

Commercial versus synthesized polymers for soil erosion control and growth of Chinese cabbage.

Science.gov (United States)

Lee, Sang Soo; Chang, Scott X; Chang, Yoon-Young; Ok, Yong Sik

2013-01-01

Soil erosion leads to environmental degradation and reduces soil productivity. The use of anionic polyacrylamide (PAM) and synthesized biopolymer (BP) using lignin, corn starch, acrylamide, and acrylic acid were tested to evaluate soil erosion, water quality, and growth of Chinese cabbage (Brassica campestris L.). Each treatment of PAM and BP was applied at 200 kg ha(-1) to loamy sand soil and subjected to a slope of 36% with a 20 mm h(-1) simulated rainfall. Application of BP decreased soil pH compared to the untreated check (CK); however, the soil pH was not altered with PAM. The decrease in pH might most likely be due to availability of anionic sites to be protonated on soils having pH >6 and soil buffering capacity. Both PAM and BP applications may not induce eutrophication with stable levels of total contents of N and P. With PAM and BP, the average values of suspended soil (SS) and turbidity were reduced by up to 96.0 and 99.9%, respectively, compared to CK. Reduction of SS can be attributed to increasing soil stability and shear strength by clay flocculation. There was no toxicity effects resulting from germination tests and the dry weight was increased by 17.7% (vs. CK) when PAM and BP were applied. These results are attributed to increases in water retention and plant-available water. The use of polymeric soil amendments is an environmentally friendly way to mitigate soil erosion and nonpoint source pollution.

Application of Coal Ash to Postmine Land for Prevention of Soil Erosion in Coal Mine in Indonesia: Utilization of Fly Ash and Bottom Ash

Directory of Open Access Journals (Sweden)

Shinji Matsumoto

2016-01-01

Full Text Available The increase in the number of coal-fired power plants with the increase in coal production and its consumption has caused the problem of the treatment of a large amount of coal ash in Indonesia. In the past studies, coal ash was applied to postmine land with the aim of improving soil conditions for plant growth; however, heavy rain in the tropical climate may cause soil erosion with the change in soil conditions. This study presents the effects of application of coal ash to postmine land on soil erosion by performing the artificial rainfall test as well as physical testing. The results indicate that the risk of soil erosion can be reduced significantly by applying the coal ash which consists of more than 85% of sand to topsoil in the postmine land at the mixing ratio of over 30%. Additionally, they reveal that not only fine fractions but also microporous structures in coal ash enhance water retention capacity by retaining water in the structure, leading to the prevention of soil erosion. Thus, the risk of soil erosion can be reduced by applying coal ash to topsoil in consideration of soil composition and microporous structure of coal ash.

On the geoethical implications of wind erosion

Science.gov (United States)

Károly, Tatárvári

2016-04-01

precipitation changes, this also increases the occurrence of bush-fires, and the growing extent of uncovered soil surface shall intensify wind erosion as well accelerating the negative effects described above. Who will be held responsible for this? Who should bear the larger cost of production in agriculture that is caused by the cost of research necessary to uncover the methods of prevention of irreversible damages caused in nature and environment? Because the field of research requires an interdisciplinary approach, research and innovation requires huge funds, the different approaches to the problem in every single field, and different reasoning methods represent a hurdle as well. In search for possible solutions it is necessary that political decision-makers adopt regulations which have solid scientific fundamentals, and also the cooperation of mankind active in science and economy is crucial. This is the only way of finding sustainable and long term solutions to the problem.

IN SITU MEASUREMENT OF BEDROCK EROSION

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D. H. Rieke-Zapp

2012-07-01

Full Text Available While long term erosion rates of bedrock material may be estimated by dating methods, current day erosion rates are – if at all available – based on rough estimates or on point measurements. Precise quantification of short term erosion rates are required to improve our understanding of short term processes, for input in landscape evolution models, as well as for studying the mechanics and efficiency of different erosion processes in varying geomorphological settings. Typical current day erosion rates in the European Alps range from sub-millimetre to several millimetres per year depending on the dominant erosion processes. The level of surveying accuracy required for recurring sub-millimetre to millimetre measurements in the field is demanding. A novel surveying setup for in-situ measurement of bedrock erosion was tested recently in three different locations in Switzerland. Natural bedrock was investigated in the Gornera gorge close to Zermatt. Further on, bedrock samples were installed in exposed locations in the Erlenbach research watershed close to Einsiedeln, and in the Illgraben debris flow channel, located in the Canton Schwyz and Valais, respectively. A twofold measurement approach was chosen for all locations. For the first setup control points providing an absolute reference frame for recurrent measurements were embedded close to the area of interest. Close range photogrammetry was applied to measure surface changes on the bedrock samples. The precision for surface measurements in the field was 0.1 mm (1 σ and thus suitable for the application. The equipment needed for the surveys can easily be carried to the field. At one field site a structured light scanner was used along with the photogrammetric setup. Although the current generation of structured light scanners appeared less suitable for field application, data acquisition was much faster and checking the data for completeness in the field was straight forward. The latest

In Situ Measurement of Bedrock Erosion

Science.gov (United States)

Rieke-Zapp, D. H.; Beer, A.; Turowski, J. M.; Campana, L.

2012-07-01

While long term erosion rates of bedrock material may be estimated by dating methods, current day erosion rates are - if at all available - based on rough estimates or on point measurements. Precise quantification of short term erosion rates are required to improve our understanding of short term processes, for input in landscape evolution models, as well as for studying the mechanics and efficiency of different erosion processes in varying geomorphological settings. Typical current day erosion rates in the European Alps range from sub-millimetre to several millimetres per year depending on the dominant erosion processes. The level of surveying accuracy required for recurring sub-millimetre to millimetre measurements in the field is demanding. A novel surveying setup for in-situ measurement of bedrock erosion was tested recently in three different locations in Switzerland. Natural bedrock was investigated in the Gornera gorge close to Zermatt. Further on, bedrock samples were installed in exposed locations in the Erlenbach research watershed close to Einsiedeln, and in the Illgraben debris flow channel, located in the Canton Schwyz and Valais, respectively. A twofold measurement approach was chosen for all locations. For the first setup control points providing an absolute reference frame for recurrent measurements were embedded close to the area of interest. Close range photogrammetry was applied to measure surface changes on the bedrock samples. The precision for surface measurements in the field was 0.1 mm (1 σ) and thus suitable for the application. The equipment needed for the surveys can easily be carried to the field. At one field site a structured light scanner was used along with the photogrammetric setup. Although the current generation of structured light scanners appeared less suitable for field application, data acquisition was much faster and checking the data for completeness in the field was straight forward. The latest generation of compact

Morphological Response of a Mud Capped Dredge Pit in Western Louisiana After Sand Excavation for Barrier Island Restoration

Science.gov (United States)

Robichaux, P. A.; Xu, K.; Bentley, S. J.; Li, C.; Miner, M. D.

2017-12-01

Sand resources play a crucial role in supporting tourism, maintaining coastal ecosystems, and protecting property and infrastructure. Mud capped dredge pits (MCDPs) are created when paleochannel sand, covered by muddy shelf overburden, is excavated for restoration purposes; such paleochannels are one significant sand resource for coastal barrier protection. However, our knowledge of MCDPs is limited. To improve understanding of their morphological behavior, a dredge pit called Peveto Channel (PC) offshore of Holly Beach, LA, was studied in 2016. Our study consisted of a survey using multiple geophysical methods, including multibeam bathymetry, sidescan sonar, subbottom profiling, and magnetometry. Results indicate that PC has undergone 100% infilling since dredging occurred. Although the pit is filled up, analyses indicate the newly deposited material is unconsolidated and has yet to equilibrate to the ambient seafloor conditions. The surface of the pit area is pockmarked and uneven, likely caused by degassing processes and differential consolidation. Sidescan sonar images confirm that the pit walls have experienced little to no lateral erosion and are well preserved. The results from this survey and from historical surveys conducted in 2003 (a few months after dredging), 2004, 2006, and 2007 are compared to previously constructed numerical models used to predict the behavior of dredge pits. To our knowledge, PC is the only filled-up offshore dredge pit in coastal Louisiana. Thus the findings of this study provide new long-term information for regulatory policies and the feasibility of MCDPs as sand resources in the future.

Soil Erosion Estimation Using Remote Sensing Techniques in Wadi Yalamlam Basin, Saudi Arabia

OpenAIRE

Bahrawi, Jarbou A.; Elhag, Mohamed; Aldhebiani, Amal Y.; Galal, Hanaa K.; Hegazy, Ahmad K.; Alghailani, Ebtisam

2016-01-01

Soil erosion is one of the major environmental problems in terms of soil degradation in Saudi Arabia. Soil erosion leads to significant on- and off-site impacts such as significant decrease in the productive capacity of the land and sedimentation. The key aspects influencing the quantity of soil erosion mainly rely on the vegetation cover, topography, soil type, and climate. This research studies the quantification of soil erosion under different levels of data availability in Wadi Yalamlam. ...

Mapping erosion from space

NARCIS (Netherlands)

Vrieling, A.

2007-01-01

Soil erosion by water is the most important land degradation problem worldwide. Spatial information on erosion is required for defining effective soil and water conservation strategies. Satellite remote sensing can provide relevant input to regional erosion assessment. This thesis comprises a review

The estimation of harmfulness for environment of moulding sand with biopolymer binder based on polylactide

Directory of Open Access Journals (Sweden)

K. Major-Gabryś

2011-01-01

Full Text Available The article takes into consideration technological and ecological aspects of IV generation moulding sands. Investigations concerning anapplication of biopolymer materials as binders for moulding sands are presented in the paper. These investigations are the continuation ofexaminations related to applications of various biopolymers as binding agents and to the properties of the moulding sands with biopolymerbinders. In the paper there are the researches concerning analyzing gases emitted from moulding sands during heating.

Laboratory test on maximum and minimum void ratio of tropical sand matrix soils

Science.gov (United States)

Othman, B. A.; Marto, A.

2018-04-01

Sand is generally known as loose granular material which has a grain size finer than gravel and coarser than silt and can be very angular to well-rounded in shape. The present of various amount of fines which also influence the loosest and densest state of sand in natural condition have been well known to contribute to the deformation and loss of shear strength of soil. This paper presents the effect of various range of fines content on minimum void ratio e min and maximum void ratio e max of sand matrix soils. Laboratory tests to determine e min and e max of sand matrix soil were conducted using non-standard method introduced by previous researcher. Clean sand was obtained from natural mining site at Johor, Malaysia. A set of 3 different sizes of sand (fine sand, medium sand, and coarse sand) were mixed with 0% to 40% by weight of low plasticity fine (kaolin). Results showed that generally e min and e max decreased with the increase of fines content up to a minimal value of 0% to 30%, and then increased back thereafter.

Finite element method for one-dimensional rill erosion simulation on a curved slope

Directory of Open Access Journals (Sweden)

Lijuan Yan

2015-03-01

Full Text Available Rill erosion models are important to hillslope soil erosion prediction and to land use planning. The development of rill erosion models and their use has become increasingly of great concern. The purpose of this research was to develop mathematic models with computer simulation procedures to simulate and predict rill erosion. The finite element method is known as an efficient tool in many other applications than in rill soil erosion. In this study, the hydrodynamic and sediment continuity model equations for a rill erosion system were solved by the Galerkin finite element method and Visual C++ procedures. The simulated results are compared with the data for spatially and temporally measured processes for rill erosion under different conditions. The results indicate that the one-dimensional linear finite element method produced excellent predictions of rill erosion processes. Therefore, this study supplies a tool for further development of a dynamic soil erosion prediction model.

Soil erosion, sedimentation and the carbon cycle

Science.gov (United States)

Cammeraat, L. H.; Kirkels, F.; Kuhn, N. J.

2012-04-01

Historically soil erosion focused on the effects of on-site soil quality loss and consequently reduced crop yields, and off-site effects related to deposition of material and water quality issues such as increased sediment loads of rivers. In agricultural landscapes geomorphological processes reallocate considerable amounts of soil and soil organic carbon (SOC). The destiny of SOC is of importance because it constitutes the largest C pool of the fast carbon cycle, and which cannot only be understood by looking at the vertical transfer of C from soil to atmosphere. Therefore studies have been carried out to quantify this possible influence of soil erosion and soil deposition and which was summarized by Quinton et al. (2010) by "We need to consider soils as mobile systems to make accurate predictions about the consequences of global change for terrestrial biogeochemical cycles and climate feedbacks". Currently a debate exists on the actual fate of SOC in relation to the global carbon cycle, represented in a controversy between researchers claiming that erosion is a sink, and those who claim the opposite. This controversy is still continuing as it is not easy to quantify and model the dominating sink and source processes at the landscape scale. Getting insight into the balance of the carbon budget requires a comprehensive research of all relevant processes at broad spatio-temporal scales, from catchment to regional scales and covering the present to the late Holocene. Emphasising the economic and societal benefits, the merits for scientific knowledge of the carbon cycle and the potential to sequester carbon and consequently offset increasing atmospheric CO2 concentrations, make the fate of SOC in agricultural landscapes a high-priority research area. Quinton, J.N., Govers, G., Van Oost, K., Bardgett, R.D., 2010. The impact of agricultural soil erosion on biogeochemical cycling. Nature Geosci, 3, 311-314.

On Pluvial Compaction of Sand

DEFF Research Database (Denmark)

Jacobsen, Moust

At the Institute of Civil Engineering in Aalborg model tests on dry sand specimens have been carried out during the last five years. To reduce deviations in test results, the sand laying technique has been carefully studied, and the sand mass spreader constructed. Preliminary results have been...

Erosive gastritis

International Nuclear Information System (INIS)

Mohammed, S.H.; Conrad, C.; Kjoergaad, J.

1982-01-01

Erosive gastritis is a well-defined radiologic and endoscopic entity. It is one of the common causes of upper gastrointestinal bleeding, yet it is seldom diagnosed and often confused with a number of other diseases. This communication re-emphasizes the characteristic endoscopic and radiologic features of erosive gastritis and its differential diagnosis. Two representative cases are reported. (orig.)

Erosive gastritis

Energy Technology Data Exchange (ETDEWEB)

Mohammed, S.H.; Conrad, C.; Kjoergaad, J.

1982-08-01

Erosive gastritis is a well-defined radiologic and endoscopic entity. It is one of the common causes of upper gastrointestinal bleeding, yet it is seldom diagnosed and often confused with a number of other diseases. This communication re-emphasizes the characteristic endoscopic and radiologic features of erosive gastritis and its differential diagnosis. Two representative cases are reported.

MORPHOMETRIC CHARACTERIZATION OF THE SAND FRACTION IN A SAND GRAIN IMAGE CAPTURE SYSTEM1

Directory of Open Access Journals (Sweden)

Lucimar Arruda Viana

Full Text Available ABSTRACT Morphology studies assume significant importance in analysis of phenomena of granular systems packaging, in particular with a view to the use of the technique of soil stabilization named particle size correction in forest roads. In this context, this study aimed to develop and operationalize a Sand Grain Image Capture System and, hereby, determine the morphological indices of the sand fractions of two sandy soils called João Pinheiro (JP and Cachoeira da Prata (CP. Soil samples, air-dried, were sieved (2.0 mm nominal mesh size for removal of gravels. The materials that passed through the sieve were subjected to dispersion, washing in 0.053 mm nominal mesh size sieve, removal of organic matter and iron oxides to obtain the clean sand fractions. Subsequently, each soil sample was sieved for separation into twelve classes, between the diameters of 0.149 mm and 1.190 mm, using a Rotap shaker. Next, tests were carried out to characterize the morphometric attributes of the twelve classes of sand fractions of the soils studied. For validation of the performance of the Sand Grain Image Capture System, the results were compared to those obtained using a standard procedure for image analysis. The analysis of the results led to the following conclusions: (i the sand fraction of the JP soil presented higher values for the morphometric indices roundness, elongation and compactness compared to sand fraction of the CP soil; and (ii the Sand Grain Image Capture System worked properly, with practicality.

Surface Heave Behaviour of Coir Geotextile Reinforced Sand Beds

Science.gov (United States)

Lal, Dharmesh; Sankar, N.; Chandrakaran, S.

2017-06-01

Soil reinforcement by natural fibers is one of the cheapest and attractive ground improvement techniques. Coir is the most abundant natural fiber available in India and due to its high lignin content; it has a larger life span than other natural fibers. It is widely used in India for erosion control purposes, but its use as a reinforcement material is rather limited. This study focuses on the use of coir geotextile as a reinforcement material to reduce surface heave phenomena occurring in shallow foundations. This paper presents the results of laboratory model tests carried out on square footings supported on coir geotextile reinforced sand beds. The influence of various parameters such as depth of reinforcement, length, and number of layers of reinforcement was studied. It was observed that surface heave is considerably reduced with the provision of geotextile. Heave reduction up to 98.7% can be obtained by the proposed method. Heave reduction is quantified by a non-dimensional parameter called heave reduction factor.

Technology unlocks tar sands energy

Energy Technology Data Exchange (ETDEWEB)

Law, C

1967-09-25

Tar sand processing technology has been developed primarily in the categories of extraction techniques and in-situ processing. In October, a $235 million venture into tar sand processing will be inspected by visitors from many points on the globe. A synthetic crude of premium quality will be flowing through a 16-in. pipeline from the Tar Island plant site of Great Canadian Oil Sands to Edmonton. This processing plant uses an extractive mining technique. The tar sand pay zone in this area averages approximately 150 ft in thickness with a 50-ft overburden. It has been estimated that the tar sands cannot be exploited when the formation thickness is less than 100 ft and overburden exceeds the same amount. This indicates that extraction techniques can only be used to recover approximately 15% of the tar sand deposits. An in-situ recovery technique developed by Shell of Canada is discussed in detail. In essence it is selective hydraulic fracturing, followed by the injection of emulsifying chemicals and steam.

Consideration of some fundamental erosion processes encountered in hypervelocity electromagnetic propulsion

International Nuclear Information System (INIS)

Buckingham, A.C.; Hawke, R.S.

1982-01-01

Experimental and theoretical research has been conducted jointly at the Livermore and Los Alamos National laboratories on dc electromagnetic railgun Lorentz accelerators. Pellets weighing a few grams to tens of grams have been launched at velocities up to better than 11 km/s. The research is addressed to attaining repeated launches of samples at hypervelocity in target impact experiments. In these experiments, shock-induced pressures in the tens of megabars range are obtained for high pressure equation-of-state research. Primary energy sources of the order of several hundred kJ to a MJ and induction currents of the order of 1 or more MA are necessary for these launches. Erosion and deformation of the conductor rails and the accelerated sample material are continuing problems. The heating, stress, and erosion resulting from simultaneous imposition of rail induction current, dense plasma (armature) interaction, current distribution, magnetic field stresses and projectile/rail contact friction are examined. It is found that while frictional heating and consequent sliding contact erosion are minor contributors to the overall erosion process, the same cannot be said for plasma impingement, penetration, and almost simultaneous induction current (Joule) heating

Effet de prétraitements des semences sur la germination de Prosopis africana (Guill., Perrot. et Rich. Taub., (Césalpiniacées

Directory of Open Access Journals (Sweden)

M'po Ifonti M'po

2009-01-01

Full Text Available Effect of Seed Treatments on the Germination of Iron Tree Prosopis africana (Guill., Perrot. et Rich. Taub. The effect of four seed treatments (i soaking in concentrate sulphuric acid for 15 mn, (ii soaking in hot water at 100 oC for 3 mm followed by in immersion into tap water for 24 hours, (iii scarification with razor blade (iv no treatment on the germination of Prosopis africana seeds was evaluated on two types of growing substrate: erosion sand and ferrallitic soil. Non treated seeds gave the highest rates of germination on the two types of growing substrate (100% on erosion sand and 89% on ferrallitic soil and by much longer duration of germination compared to treated seeds (46 days on erosion sand and 42 days on ferrallitic soil. Overall, germination is better (rates and speed on erosion sand. Treatments of the seeds in concentrate sulphuric acid are prejudicial to the survival of the embryo and yield low germination rates (30% on erosion sand and 20% on ferrallitic soil. Scarification by razor blade and soaking in hot water at 100 oC gave the highest germination rate (85%, 18 days after sowing on erosion sand and allowed to accelerate the germination. Because of their simplicity and their low cost, these two seed treatments can be recommended for planters and the use of erosion sand for the sowing.

Slurry Erosion Behavior of AlxCoCrFeNiTi0.5 High-Entropy Alloy Coatings Fabricated by Laser Cladding

Directory of Open Access Journals (Sweden)

Jianhua Zhao

2018-02-01

Full Text Available High-entropy alloys (HEAs have gained extensive attention due to their excellent properties and the related scientific value in the last decade. In this work, AlxCoCrFeNiTi0.5 HEA coatings (x: molar ratio, x = 1.0, 1.5, 2.0, and 2.5 were fabricated on Q345 steel substrate by laser-cladding process to develop a practical protection technology for fluid machines. The effect of Al content on their phase evolution, microstructure, and slurry erosion performance of the HEA coatings was studied. The AlxCoCrFeNiTi0.5 HEA coatings are composed of simple face-centered cubic (FCC, body-centered cubic (BCC and their mixture phase. Slurry erosion tests were conducted on the HEA coatings with a constant velocity of 10.08 m/s and 16–40 meshs and particles at impingement angles of 15, 30, 45, 60 and 90 degrees. The effect of three parameters, namely impingement angle, sand concentration and erosion time, on the slurry erosion behavior of AlxCoCrFeNiTi0.5 HEA coatings was investigated. Experimental results show AlCoCrFeNiTi0.5 HEA coating follows a ductile erosion mode and a mixed mode (neither ductile nor brittle for Al1.5CoCrFeNiTi0.5 HEA coating, while Al2.0CoCrFeNiTi0.5 and Al2.5CoCrFeNiTi0.5 HEA coatings mainly exhibit brittle erosion mode. AlCoCrFeNiTi0.5 HEA coating has good erosion resistance at all investigated impingement angles due to its high hardness, good plasticity, and low stacking fault energy (SFE.

Testing the effectiveness of pine needlecast in reducing post-fire soil erosion using complementary experimental approaches

Science.gov (United States)

Bento, C. P. M.; Shakesby, R. A.; Walsh, R. P. D.; Ferreira, C. S. S.; Ferreira, A. J. D.; Urbanek, E.

2012-04-01

Mediterranean wildfire activity has increased markedly in recent decades, leading to enhanced runoff and erosion. Limiting post-fire on-site soil degradation and off-site flooding and sedimentation, however, often has a low priority because of the high costs of materials and labour needed to implement many recognised techniques (e.g. seeding, hydromulching, installing logs along the contour). However, in pine plantations, the crowns may only be scorched so that after fire the needlecast can form a comparatively dense ground cover. Its post-fire erosion-limiting effectiveness is virtually unknown in the Mediterranean context, despite potentially protecting soil with minimal effort (requiring only a delay to existing salvage logging procedures at most). As part of the DESIRE research programme, this paper presents results from two complementary approaches testing the erosion-limiting effectiveness of needlecast. (1) Near Moinhos, central Portugal, two 8m2 erosion plots were established immediately post-fire in September 2009 on a steep (30°) slope representative of an adjacent burnt Pinus pinaster plantation. Soil erosion was monitored during a 3-month pre-treatment phase. Needles were then applied to one plot at a density (37.7% cover) measured on a post-fire pine plantation. Soil losses from treated and untreated plots were then monitored until April 2011. By taking the percentage increase or decrease in erosion between the two monitoring phases for the untreated control plot as the 'expected' pattern, the erosion-limiting effectiveness of needles applied to the treated plot could then be determined. (2) Six adjacent rectangular 1.23m2 lysimeters were filled with gravel and sand, and capped by 10 cm of topsoil taken from a long unburnt Pinus pinaster plantation. They were set at 15° and left open to natural rainfall. This angle was considered the steepest possible from logistical and soil stability points of view. All lysimeters underwent a phase under bare soil

Methods and scales in soil erosion studies in Spain: problems and perspectives

Energy Technology Data Exchange (ETDEWEB)

Garcia-Ruiz, J. M.

2009-07-01

Soil erosion is a major problem in some areas of Spain. Research groups have studied a variety of aspects of this problem indifferent environments, and at a range of scales using a diversity of methods, from piquettes and rainfall simulation to experimental plots, catchment and large regional areas. This has increased knowledge and identified the main problems: farmland abandonment, badlands erosion, the effects of land use changes, and the role of extreme events and erosion in certain crops (particularly vineyards). However, comparison of results among various research groups has been difficult, posing problems in developing solutions from State and Regional administrators. (Author) 73 refs.

Assessing storm erosion hazards

NARCIS (Netherlands)

Ranasinghe, Ranasinghe W M R J B; Callaghan, D.; Ciavola, Paolo; Coco, Giovanni

2017-01-01

The storm erosion hazard on coasts is usually expressed as an erosion volume and/or associated episodic coastline retreat. The accurate assessment of present-day and future storm erosion volumes is a key task for coastal zone managers, planners and engineers. There are four main approaches that can

Mapping Soil Erosion Factors and Potential Erosion Risk for the National Park "Central Balkan"

Science.gov (United States)

Ilieva, Diliana; Malinov, Ilia

2014-05-01

Soil erosion is widely recognised environmental problem. The report aims at presenting the main results from assessment and mapping of the factors of sheet water erosion and the potential erosion risk on the territory of National Park "Central Balkan". For this purpose, the Universal Soil Loss Equation (USLE) was used for predicting soil loss from erosion. The influence of topography (LS-factor) and soil erodibility (K-factor) was assessed using small-scale topographic and soil maps. Rainfall erosivity (R-factor) was calculated from data of rainfalls with amounts exceeding 9.5 mm from 14 hydro-meteorological stations. The values of the erosion factors (R, K and LS) were presented for the areas of forest, sub-alpine and alpine zones. Using the methods of GIS, maps were plotted presenting the area distribution among the classes of the soil erosion factors and the potential risk in the respective zones. The results can be used for making accurate decisions for soil conservation and sustainable land management in the park.

Turbulent Flow and Sand Dune Dynamics: Identifying Controls on Aeolian Sediment Transport

Science.gov (United States)

Weaver, C. M.; Wiggs, G.

2007-12-01

Sediment transport models are founded on cubic power relationships between the transport rate and time averaged flow parameters. These models have achieved limited success and recent aeolian and fluvial research has focused on the modelling and measurement of sediment transport by temporally varying flow conditions. Studies have recognised turbulence as a driving force in sediment transport and have highlighted the importance of coherent flow structures in sediment transport systems. However, the exact mechanisms are still unclear. Furthermore, research in the fluvial environment has identified the significance of turbulent structures for bedform morphology and spacing. However, equivalent research in the aeolian domain is absent. This paper reports the findings of research carried out to characterise the importance of turbulent flow parameters in aeolian sediment transport and determine how turbulent energy and turbulent structures change in response to dune morphology. The relative importance of mean and turbulent wind parameters on aeolian sediment flux was examined in the Skeleton Coast, Namibia. Measurements of wind velocity (using sonic anemometers) and sand transport (using grain impact sensors) at a sampling frequency of 10 Hz were made across a flat surface and along transects on a 9 m high barchan dune. Mean wind parameters and mass sand flux were measured using cup anemometers and wedge-shaped sand traps respectively. Vertical profile data from the sonic anemometers were used to compute turbulence and turbulent stress (Reynolds stress; instantaneous horizontal and vertical fluctuations; coherent flow structures) and their relationship with respect to sand transport and evolving dune morphology. On the flat surface time-averaged parameters generally fail to characterise sand transport dynamics, particularly as the averaging interval is reduced. However, horizontal wind speed correlates well with sand transport even with short averaging times. Quadrant

Quantifying and modeling soil erosion and sediment export from construction sites in southern California

Science.gov (United States)

Wernet, A. K.; Beighley, R. E.

2006-12-01

Soil erosion is a power process that continuously alters the Earth's landscape. Human activities, such as construction and agricultural practices, and natural events, such as forest fires and landslides, disturb the landscape and intensify erosion processes leading to sudden increases in runoff sediment concentrations and degraded stream water quality. Understanding soil erosion and sediment transport processes is of great importance to researchers and practicing engineers, who routinely use models to predict soil erosion and sediment movement for varied land use and climate change scenarios. However, existing erosion models are limited in their applicability to constructions sites which have highly variable soil conditions (density, moisture, surface roughness, and best management practices) that change often in both space and time. The goal of this research is to improve the understanding, predictive capabilities and integration of treatment methodologies for controlling soil erosion and sediment export from construction sites. This research combines modeling with field monitoring and laboratory experiments to quantify: (a) spatial and temporal distribution of soil conditions on construction sites, (b) soil erosion due to event rainfall, and (c) potential offsite discharge of sediment with and without treatment practices. Field sites in southern California were selected to monitor the effects of common construction activities (ex., cut/fill, grading, foundations, roads) on soil conditions and sediment discharge. Laboratory experiments were performed in the Soil Erosion Research Laboratory (SERL), part of the Civil and Environmental Engineering department at San Diego State University, to quantify the impact of individual factors leading to sediment export. SERL experiments utilize a 3-m by 10-m tilting soil bed with soil depths up to 1 m, slopes ranging from 0 to 50 percent, and rainfall rates up to 150 mm/hr (6 in/hr). Preliminary modeling, field and laboratory

The Effect of Rainfall Intensity on Soil Erosion and Runoff for Latosol Soil in Indonesia

OpenAIRE

Sukartaatmadja, Sukandi; Sato, Yohei; Yamaji, Eiji; Ishikawa, Masaya

2003-01-01

Soil erosion is the most serious problem of land degradation in Indonesia. However, limited report has been documented. The erosion problem in Indonesia, particularly in Java, has been at an alarming rate. The fundamental 1 case of soil erosion is the rain effect upon the soil. Rainfall intensity and soil characteristics are related to soil erosion and runoff The objective of this research was to study the relationship of rainfall intensity, soil erosion and runoff in latosol s...

Monitoring Riverbank Erosion in Mountain Catchments Using Terrestrial Laser Scanning

Directory of Open Access Journals (Sweden)

Laura Longoni

2016-03-01

Full Text Available Sediment yield is a key factor in river basins management due to the various and adverse consequences that erosion and sediment transport in rivers may have on the environment. Although various contributions can be found in the literature about sediment yield modeling and bank erosion monitoring, the link between weather conditions, river flow rate and bank erosion remains scarcely known. Thus, a basin scale assessment of sediment yield due to riverbank erosion is an objective hard to be reached. In order to enhance the current knowledge in this field, a monitoring method based on high resolution 3D model reconstruction of riverbanks, surveyed by multi-temporal terrestrial laser scanning, was applied to four banks in Val Tartano, Northern Italy. Six data acquisitions over one year were taken, with the aim to better understand the erosion processes and their triggering factors by means of more frequent observations compared to usual annual campaigns. The objective of the research is to address three key questions concerning bank erosion: “how” erosion happens, “when” during the year and “how much” sediment is eroded. The method proved to be effective and able to measure both eroded and deposited volume in the surveyed area. Finally an attempt to extrapolate basin scale volume for bank erosion is presented.

The influence of rill density on soil erosion against USLE-soil erosion methode

OpenAIRE

Rizalihadi, A.M.; Faimah, B.E.; Nazia, C.L.

2013-01-01

Land and water is one of the major natural resource which has an important role for human life. Exploitation of land in catchment areas that not correspond to its carrying capacity will cause damage. One of the effect is increassing the soil erosion. Continuous erosion will also lead to increased sediment transport in rivers that disrupt the ship navigation on estuary due sediment accumulation. At present, soil erosion is estimated using USLE method, which is only limited to the erosion in th...

Prediction of Soil Erosion Rates in Japan where Heavily Forested Landscape with Unstable Terrain

Science.gov (United States)

Nanko, K.; Oguro, M.; Miura, S.; Masaki, T.

2016-12-01

Soil is fundamental for plant growth, water conservation, and sustainable forest management. Multidisciplinary interest in the role of the soil in areas such as biodiversity, ecosystem services, land degradation, and water security has been growing (Miura et al., 2015). Forest is usually protective land use from soil erosion because vegetation buffers rainfall power and erosivity. However, some types of forest in Japan show high susceptibility to soil erosion due to little ground cover and steep slopes exceeding thirty degree, especially young Japanese cypress (Chamaecyparis obtusa) plantations (Miura et al., 2002). This is a critical issue for sustainable forest management because C. obtusaplantations account for 10% of the total forest coverage in Japan (Forestry Agency, 2009). Prediction of soil erosion rates on nationwide scale is necessary to make decision for future forest management plan. To predict and map soil erosion rates across Japan, we applied three soil erosion models, RUSLE (Revised Universal Soil Loss Equation, Wischmeier and Smith, 1978), PESERA (Pan-European Soil Erosion Risk Assessment, Kirkby et al., 2003), and RMMF (Revised Morgan-Morgan-Finney, Morgan, 2001). The grid scale is 1-km. RUSLE and PESERA are most widely used erosion models today. RMMF includes interactions between rainfall and vegetation, such as canopy interception and ratio of canopy drainage in throughfall. Evaporated rainwater by canopy interception, generally accounts for 15-20% in annual rainfall, does not contribute soil erosion. Whereas, larger raindrops generated by canopy drainage produced higher splash erosion rates than gross rainfall (Nanko et al., 2008). Therefore, rainfall redistribution process in canopy should be considered to predict soil erosion rates in forested landscape. We compared the results from three erosion models and analyze the importance of environmental factors for the prediction of soil erosion rates. This research was supported by the Environment

Preventing erosive risks after wildfire in Spain: advances and gaps

Science.gov (United States)

Fernández Filgueira, Cristina; Vega Hidalgo, José A.; Fontúrbel Lliteras, Teresa

2017-04-01

Galicia (NW Spain) is one of the most wildfire-affected areas in Western Europe and where the highest soil losses following fire are recorded in the Iberian Peninsula. During the last decade, mitigation of hydrological and erosive risk has been an important objective for researchers and forest managers. For this reason, research carried out has focused on three main issues: i) the development of operational tools to prioritize post-fire soil stabilization actions, based on soil burn severity indicators and remote sensed information, and testing of their ability to reflect degradation risk in relevant soil properties and subsequent soil erosion, ii) the development and testing of different soil stabilization treatments and their effectiveness for reducing erosion, following their application at broad scale, under the specific environmental conditions of Galicia and iii) the assessment of the performance of current erosion models as well as the development of empirical models to predict post-fire soil losses. On the other hand, the use of forest resources is an essential component of the regional incomes in NW Spain and consequently there is a pressing necessity for investigation on techniques suitable for reconciling soil conservation and sustainable use of those resources. In the framework of wildfire impacts this involve many and complex challenges. This scenario contrast with most of the Iberian Peninsula under Mediterranean influence where salvage logging is not a priority. As in other regions, post-fire hydrologic and erosive risk modeling, including threatened resources vulnerability evaluation is also a capital research need, particularly in a climate change context where dramatic changes in drivers such as precipitation, evapotranspiration and fire regime are expected. The study was funded by the National Institute of Agricultural Research of Spain (INIA) through project RTA2014-00011-C06-02, cofunded by FEDER and the Plan de Mejora e Innovación Forestal de

Oil sands tax expenditures

International Nuclear Information System (INIS)

Ketchum, K; Lavigne, R.; Plummer, R.

2001-01-01

The oil sands are a strategic Canadian resource for which federal and provincial governments provide financial incentives to develop and exploit. This report describes the Oil Sands Tax Expenditure Model (OSTEM) developed to estimate the size of the federal income tax expenditure attributed to the oil sands industry. Tax expenditures are tax concessions which are used as alternatives to direct government spending for achieving government policy objectives. The OSTEM was developed within the business Income Tax Division of Canada's Department of Finance. Data inputs for the model were obtained from oil sands developers and Natural Resources Canada. OSTEM calculates annual revenues, royalties and federal taxes at project levels using project-level projections of capital investment, operating expenses and production. OSTEM calculates tax expenditures by comparing taxes paid under different tax regimes. The model also estimates the foregone revenue as a percentage of capital investment. Total tax expenditures associated with investment in the oil sands are projected to total $820 million for the period from 1986 to 2030, representing 4.6 per cent of the total investment. 10 refs., 2 tabs., 7 figs

Study on of Seepage Flow Velocity in Sand Layer Profile as Affected by Water Depth and Slope Gradience

Science.gov (United States)

Han, Z.; Chen, X.

2017-12-01

BACKGROUND: The subsurface water flow velocity is of great significance in understanding the hydrodynamic characteristics of soil seepage and the influence of interaction between seepage flow and surface runoff on the soil erosion and sediment transport process. OBJECTIVE: To propose a visualized method and equipment for determining the seepage flow velocity and measuring the actual flow velocity and Darcy velocity as well as the relationship between them.METHOD: A transparent organic glass tank is used as the test soil tank, the white river sand is used as the seepage test material and the fluorescent dye is used as the indicator for tracing water flow, so as to determine the thickness and velocity of water flow in a visualized way. Water is supplied at the same flow rate (0.84 L h-1) to the three parts with an interval of 1m at the bottom of the soil tank and the pore water velocity and the thickness of each water layer are determined under four gradient conditions. The Darcy velocity of each layer is calculated according to the water supply flow and the discharge section area. The effective discharge flow pore is estimated according to the moisture content and porosity and then the relationship between Darcy velocity and the measured velocity is calculated based on the water supply flow and the water layer thickness, and finally the correctness of the calculation results is verified. RESULTS: According to the velocity calculation results, Darcy velocity increases significantly with the increase of gradient; in the sand layer profile, the flow velocity of pore water at different depths increases with the increase of gradient; under the condition of the same gradient, the lower sand layer has the maximum flow velocity of pore water. The air-filled porosity of sand layer determines the proportional relationship between Darcy velocity and pore flow velocity. CONCLUSIONS: The actual flow velocity and Darcy velocity can be measured by a visualized method and the

Auto consolidated cohesive sediments erosion; Erosion des sediments cohesifs en autoconsolidation

Energy Technology Data Exchange (ETDEWEB)

Ternat, F

2007-02-15

Pollutants and suspended matters of a river can accumulate into the sedimentary column. Once deposited, they are submitted to self-weight consolidation processes, ageing and burying, leading to an increase of their erosion resistance. Pollutant fluxes can be related to sedimentary fluxes, determined by threshold laws. In this work, an erosion threshold model is suggested by introducing a cohesion force into the usual force balance. A model of cohesion is developed on the basis of interactions between argillaceous cohesive particles (clays), particularly the Van der Waals force, whose parameterization is ensured by means of granulometry and porosity. Artificial erosion experiments were performed in a recirculating erosion flume with natural cored sediments where critical shear stress measurements were performed. Other analyses provided granulometry and porosity. The results obtained constitute a good database for the literature. The model is then applied to the experimental conditions and gives good agreement with measurements. An example of the accounting for self-weight consolidation processes is finally suggested, before finishing on a Mohr like diagram dedicated to soft cohesive sediment erosion. (author)

PERENCANAAN SAND POCKET SEBAGAI BANGUNAN PENGENDALI ALIRAN SEDIMEN DI KALI OPAK YOGYAKARTA

Directory of Open Access Journals (Sweden)

Yeri Sutopo

2016-07-01

Full Text Available This research conducted in Opak River, in Yogyakarta. This river has broad (river flow area 27,04 km2, and 20,11 km in length. The research objective is to make a planning about effective rainfall in 50 years and found the Opak Sand Pocket design. This research used methods with direct-survey in location, and collected secondary data from related agencies. From the data, it was obtained the value of precipitation the design, discharge flood design, dimensions of building hydrolic design (Main Dam, Sub Dam, Apron, and analysis the effectiveness of sand pocket in reducing the sediment that has happened. Based on the results of the research, discharge maximum ( Q50 that occurs in the river of 202,77 m3/s. So it can be calculated that sand pocket designed will have wide of apron 54,04 m, with total high of Main Dam 6 m, total high of Sub Dam 6 m, length of apron 10 m, thick of apron 0,96 m. Based on the ability of sand pocket in reducing the rate of the sediment that is happened, the building has effectiveness until 90,20 % in reducing bed load based on the calculation. Therefore, it can be argued that the building has been effective to reduce the speed of sediment occurring in Opak River.

Erosion and Sedimentation from the Bagley Fire, Eastern Klamath Mountains, Northern CA

Science.gov (United States)

De La Fuente, J. A.; Bachmann, S.; Mai, C.; Mikulovsky, R.; Mondry, Z. J.; Rust, B.; Young, D.

2014-12-01

The Bagley Fire burned about 19,000 hectares on the Shasta-Trinity National Forest in the late summer of 2012, with soil burn severities of 11% high, 19% moderate and 48% low. Two strong storms in November and December followed the fire. The first storm had a recurrence interval of about 2 years, and generated runoff with a return interval of 10-25 years, causing many road stream crossing failures in parts of the fire. The second storm had a recurrence interval of 25-50 years, and initiated more severe erosion throughout the fire area. Erosional processes were dominated by sheet, rill and gully erosion, and landslides were uncommon. A model predicted high potential for debris flows, but few were documented, and though most stream channels exhibited fresh scour and deposition, residual deposits lacked boulder levees or other evidence of debris flow. Rather, deposits were stratified and friable, suggesting a sediment laden flood flow rather than debris flow origin. The resulting sediment was rich in gravel and finer particles, and poor in larger rock. Soil loss was estimated at 0.5-5.6 cm on most hillslopes. A high resolution DEM (LiDAR) was used to measure gullies, small landslides, and stream scour, and also to estimate sedimentation in Squaw Creek, and Shasta Lake. A soil erosion model was used to estimate surface erosion. Total erosion in the Squaw Creek watershed was estimated at 2.24 million metric tons, which equates to 260 metric tons/hectare. Of this, about 0.89 million metric tons were delivered to the stream system (103 metric tons/hectare). Nearly half of this sediment, 0.41 million metric tons, was temporarily stored in the Squaw Creek channel, and around 0.33 million metric tons of fine sediment were carried into Shasta Lake. Squaw Creek also delivered about 0.17 million metric tons of sand, gravel and cobbles to the lake. This estimate is very tenuous, and was made by measuring the volume of a delta in Shasta Lake from a tributary to Squaw Creek and

Crushed and River-Origin Sands Used as Aggregates in Repair Mortars

Directory of Open Access Journals (Sweden)

Maria Stefanidou

2016-04-01

Full Text Available The systematic analysis of mortars from monuments or historic buildings and the simultaneous study of the construction environment show that it was common practice to use naturally occurring sand from local rivers or streams for the production of the mortars. There are cases though, mainly on islands, where sands of natural origin were limited, and marine or crushed sands were used possibly after elaboration. In all cases the particle size analysis of old mortar confirms the presence of even distribution of the granules. As regards the design of the repair mortars, there are criteria that should be taken into consideration in order to produce materials with compatible properties. The main properties concerning sands are the grain distribution and maximum size, the color, the content of fines, and soluble salts. The objective of this research is the study of the physical characteristics of the sands such as the sand equivalent, the gradation, the apparent density, the morphology of the grains, their mineralogical composition and the influence of these properties on the behavior of lime mortars, notably the mechanical and physical properties acquired.

Rainfall erosivity in Europe.

Science.gov (United States)

Panagos, Panos; Ballabio, Cristiano; Borrelli, Pasquale; Meusburger, Katrin; Klik, Andreas; Rousseva, Svetla; Tadić, Melita Perčec; Michaelides, Silas; Hrabalíková, Michaela; Olsen, Preben; Aalto, Juha; Lakatos, Mónika; Rymszewicz, Anna; Dumitrescu, Alexandru; Beguería, Santiago; Alewell, Christine

2015-04-01

Rainfall is one the main drivers of soil erosion. The erosive force of rainfall is expressed as rainfall erosivity. Rainfall erosivity considers the rainfall amount and intensity, and is most commonly expressed as the R-factor in the USLE model and its revised version, RUSLE. At national and continental levels, the scarce availability of data obliges soil erosion modellers to estimate this factor based on rainfall data with only low temporal resolution (daily, monthly, annual averages). The purpose of this study is to assess rainfall erosivity in Europe in the form of the RUSLE R-factor, based on the best available datasets. Data have been collected from 1541 precipitation stations in all European Union (EU) Member States and Switzerland, with temporal resolutions of 5 to 60 min. The R-factor values calculated from precipitation data of different temporal resolutions were normalised to R-factor values with temporal resolutions of 30 min using linear regression functions. Precipitation time series ranged from a minimum of 5 years to a maximum of 40 years. The average time series per precipitation station is around 17.1 years, the most datasets including the first decade of the 21st century. Gaussian Process Regression (GPR) has been used to interpolate the R-factor station values to a European rainfall erosivity map at 1 km resolution. The covariates used for the R-factor interpolation were climatic data (total precipitation, seasonal precipitation, precipitation of driest/wettest months, average temperature), elevation and latitude/longitude. The mean R-factor for the EU plus Switzerland is 722 MJ mm ha(-1) h(-1) yr(-1), with the highest values (>1000 MJ mm ha(-1) h(-1) yr(-1)) in the Mediterranean and alpine regions and the lowest (<500 MJ mm ha(-1) h(-1) yr(-1)) in the Nordic countries. The erosivity density (erosivity normalised to annual precipitation amounts) was also the highest in Mediterranean regions which implies high risk for erosive events and floods

Singing Sand Dunes

Indian Academy of Sciences (India)

ble low-frequency (s. 75–105 Hz), that can some- times be heard up to 10 km away. Scientific in- vestigations suggest that the sustained low fre- quency sound of sand dunes that resembles a pure note from a musical instrument, is due to the synchronized motion of well-sorted dry sand grains when they spontaneously ...

Immunohistochemical Study of p53 Expression in Patients with Erosive and Non-Erosive Oral Lichen Planus

Science.gov (United States)

Shiva, Atena; Zamanian, Ali; Arab, Shahin; Boloki, Mahsa

2018-01-01

Statement of the Problem: Oral lichen planus is a common mucocutaneous lesion with a chronic inflammatory process mediated by immune factors while a few cases of the disease become malignant. Purpose: This study aimed to determine the frequency of p53 marker as a tumor suppressor in patients with erosive and non-erosive oral lichen planus (OLP) by using immunohistochemical methods. Materials and Method: This descriptive cross-sectional study investigated the p53 expression in 16 erosive OLP, 16 non-erosive OLP samples, and 8 samples of normal oral mucosa through immunohistochemistry. The percentage of stained cells in basal and suprabasal layers, and inflammatory infiltrate were graded according to the degree of staining; if 0%, 50% of the cells were stained, they were considered as (-), (+), (++), (+++) and (++++), respectively. The obtained data was statistically analyzed and compared by using Chi square and Fisher’s exact test. Results: The mean percentage of p53 positive cells in erosive OLP (34.5±14.2) was considerably higher than that in non-erosive OLP (23.8±10.4) and normal mucosa (17.5±17). There was a significant difference among the three groups of erosive, non-erosive and control in terms of staining intensity. No significant difference existed between the patients’ age and sex in the two OLP groups. Conclusion: The increased incidence of p53 from normal mucosa to erosive OLP indicated the difference between biological behavior of erosive and non-erosive OLP. It can be claimed that the erosive OLP has great premalignant potential compared with the non-erosive one.

Communicating and Visualizing Erosion-associated Risks to Infrastructure

Science.gov (United States)

Hewett, Caspar; Simpson, Carolyn; Wainwright, John

2016-04-01

Soil erosion is a major problem worldwide, affecting agriculture, the natural environment and urban areas through its impact on flood risk, water quality, loss of nutrient-rich upper soil layers, eutrophication of water bodies, sedimentation of waterways and sediment-related damage to roads, buildings and infrastructure such as water, gas and electricity supply networks. This study focuses on risks to infrastructure associated with erosion and the interventions needed to reduce those risks. Deciding on what interventions to make means understanding better which parts of the landscape are most susceptible to erosion and which measures are most effective in reducing it. Effective ways of communicating mitigation strategies to stakeholders such as farmers, land managers and policy-makers are then essential if interventions are to be implemented. Drawing on the Decision-Support Matrix (DSM) approach which combines a set of hydrological principles with Participatory Action Research (PAR), a decision-support tool for Communicating and Visualizing Erosion-Associated Risks to Infrastructure (CAVERTI) was developed. The participatory component was developed with the Wear Rivers Trust, focusing on a case-study area in the North East of England. The CAVERTI tool brings together process understanding gained from modelling with knowledge and experience of a variety of stakeholders to address directly the problem of sediment transport. Development of the tool was a collaborative venture, ensuring that the problems and solutions presented are easily recognised by practitioners and decision-makers. This recognition, and ease of access via a web-based interface, in turn help to ensure that the tools get used. The web-based tool developed helps to assess, manage and improve understanding of risk from a multi-stakeholder perspective and proposes solutions to problems. We argue that visualization and communication tools co-developed by researchers and stakeholders are the best means

[Effects and mechanisms of plant roots on slope reinforcement and soil erosion resistance: a research review].

Science.gov (United States)

Xiong, Yan-Mei; Xia, Han-Ping; Li, Zhi-An; Cai, Xi-An

2007-04-01

Plant roots play an important role in resisting the shallow landslip and topsoil erosion of slopes by raising soil shear strength. Among the models in interpreting the mechanisms of slope reinforcement by plant roots, Wu-Waldron model is a widely accepted one. In this model, the reinforced soil strength by plant roots is positively proportional to average root tensile strength and root area ratio, the two most important factors in evaluating slope reinforcement effect of plant roots. It was found that soil erosion resistance increased with the number of plant roots, though no consistent quantitative functional relationship was observed between them. The increase of soil erosion resistance by plant roots was mainly through the actions of fiber roots less than 1 mm in diameter, while fiber roots enhanced the soil stability to resist water dispersion via increasing the number and diameter of soil water-stable aggregates. Fine roots could also improve soil permeability effectively to decrease runoff and weaken soil erosion.

Field studies of erosion-control technologies for arid shallow land-burial sites at Los Alamos

International Nuclear Information System (INIS)

Nyhan, J.W.; Abeele, W.V.; DePoorter, G.L.; Hakonson, T.E.; Perkins, B.A.; Foster, G.R.

1983-01-01

The field research program involving corrective measures technologies for arid shallow land-burial sites is described. Research performed for a portion of this task, the identification, evaluation, and modeling of erosion control technologies, is presented in detail. In a joint study with USDA-ARS, soil erosion and infiltration of water into a simulated trench cap with various surface treatments was measured and compared with data from undisturbed soil surfaces with natural plant cover. The distribution of soil particles in the runoff was measured for inclusion in CREAMS (a field scale model for Chemicals, Runoff and Erosion from Agricultural Management Systems). Neutron moisture gauge data collected beneath the erosion plots are presented to show the seasonal effects of the erosion control technologies on the subsurface component of water balance. 12 references, 4 figures, 4 tables

Ecological site-based assessments of wind and water erosion: informing accelerated soil erosion management in rangelands

Science.gov (United States)

Webb, Nicholas P.; Herrick, Jeffrey E.; Duniway, Michael C.

2014-01-01

Accelerated soil erosion occurs when anthropogenic processes modify soil, vegetation or climatic conditions causing erosion rates at a location to exceed their natural variability. Identifying where and when accelerated erosion occurs is a critical first step toward its effective management. Here we explore how erosion assessments structured in the context of ecological sites (a land classification based on soils, landscape setting and ecological potential) and their vegetation states (plant assemblages that may change due to management) can inform systems for reducing accelerated soil erosion in rangelands. We evaluated aeolian horizontal sediment flux and fluvial sediment erosion rates for five ecological sites in southern New Mexico, USA, using monitoring data and rangeland-specific wind and water erosion models. Across the ecological sites, plots in shrub-encroached and shrub-dominated vegetation states were consistently susceptible to aeolian sediment flux and fluvial sediment erosion. Both processes were found to be highly variable for grassland and grass-succulent states across the ecological sites at the plot scale (0.25 Ha). We identify vegetation thresholds that define cover levels below which rapid (exponential) increases in aeolian sediment flux and fluvial sediment erosion occur across the ecological sites and vegetation states. Aeolian sediment flux and fluvial erosion in the study area can be effectively controlled when bare ground cover is 100 cm in length is less than ~35%. Land use and management activities that alter cover levels such that they cross thresholds, and/or drive vegetation state changes, may increase the susceptibility of areas to erosion. Land use impacts that are constrained within the range of natural variability should not result in accelerated soil erosion. Evaluating land condition against the erosion thresholds identified here will enable identification of areas susceptible to accelerated soil erosion and the development of

Ecological site‐based assessments of wind and water erosion: informing accelerated soil erosion management in rangelands.

Science.gov (United States)

Webb, Nicholas P; Herrick, Jeffrey E; Duniway, Michael C

Accelerated soil erosion occurs when anthropogenic processes modify soil, vegetation, or climatic conditions causing erosion rates at a location to exceed their natural variability. Identifying where and when accelerated erosion occurs is a critical first step toward its effective management. Here we explored how erosion assessments structured in the context of ecological sites (a land classification based on soils, landscape setting, and ecological potential) and their vegetation states (plant assemblages that may change due to management) can inform systems for reducing accelerated soil erosion in rangelands. We evaluated aeolian horizontal sediment flux and fluvial sediment erosion rates for five ecological sites in southern New Mexico, USA, using monitoring data and rangeland-specific wind and water erosion models. Across the ecological sites, plots in shrub-encroached and shrub-dominated vegetation states were consistently susceptible to aeolian sediment flux and fluvial sediment erosion. Both processes were found to be highly variable for grassland and grass–succulent states across the ecological sites at the plot scale (0.25 ha). We identified vegetation thresholds that define cover levels below which rapid (exponential) increases in aeolian sediment flux and fluvial sediment erosion occur across the ecological sites and vegetation states. Aeolian sediment flux and fluvial erosion in the study area could be effectively controlled when bare ground cover was 100 cm in length was less than ∼35%. Land use and management activities that alter cover levels such that they cross thresholds, and/or drive vegetation state changes, may increase the susceptibility of areas to erosion. Land use impacts that are constrained within the range of natural variability should not result in accelerated soil erosion. Evaluating land condition against the erosion thresholds identified here will enable identification of areas susceptible to accelerated soil erosion and the

The extraction of bitumen from western oil sands. Annual report, July 1991--July 1992

Energy Technology Data Exchange (ETDEWEB)

Oblad, A.G.; Bunger, J.W.; Dahlstrom, D.A.; Deo, M.D.; Hanson, F.V.; Miller, J.D.; Seader, J.D.

1992-08-01

The University of Utah tar sand research and development program is concerned with research and development on Utah is extensive oil sands deposits. The program has been intended to develop a scientific and technological base required for eventual commercial recovery of the heavy oils from oil sands and processing these oils to produce synthetic crude oil and other products such as asphalt. The overall program is based on mining the oil sand, processing the mined sand to recover the heavy oils and upgrading them to products. Multiple deposits are being investigated since it is believed that a large scale (approximately 20,000 bbl/day) plant would require the use of resources from more than one deposit. The tasks or projects in the program are organized according to the following classification: Recovery technologies which includes thermal recovery methods, water extraction methods, and solvent extraction methods; upgrading and processing technologies which covers hydrotreating, hydrocracking, and hydropyrolysis; solvent extraction; production of specialty products; and environmental aspects of the production and processing technologies. These tasks are covered in this report.

Sand Impact Tests of a Half-Scale Crew Module Boilerplate Test Article

Science.gov (United States)

Vassilakos, Gregory J.; Hardy, Robin C.

2012-01-01

Although the Orion Multi-Purpose Crew Vehicle (MPCV) is being designed primarily for water landings, a further investigation of launch abort scenarios reveals the possibility of an onshore landing at Kennedy Space Center (KSC). To gather data for correlation against simulations of beach landing impacts, a series of sand impact tests were conducted at NASA Langley Research Center (LaRC). Both vertical drop tests and swing tests with combined vertical and horizontal velocity were performed onto beds of common construction-grade sand using a geometrically scaled crew module boilerplate test article. The tests were simulated using the explicit, nonlinear, transient dynamic finite element code LS-DYNA. The material models for the sand utilized in the simulations were based on tests of sand specimens. Although the LSDYNA models provided reasonable predictions for peak accelerations, they were not always able to track the response through the duration of the impact. Further improvements to the material model used for the sand were identified based on results from the sand specimen tests.

The Arctic Coastal Erosion Problem

Energy Technology Data Exchange (ETDEWEB)

Frederick, Jennifer M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Thomas, Matthew Anthony [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bull, Diana L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jones, Craig A. [Integral Consulting Inc., San Francisco, CA (United States); Roberts, Jesse D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2016-09-01

Permafrost-dominated coastlines in the Arctic are rapidly disappearing. Arctic coastal erosion rates in the United States have doubled since the middle of the twentieth century and appear to be accelerating. Positive erosion trends have been observed for highly-variable geomorphic conditions across the entire Arctic, suggesting a major (human-timescale) shift in coastal landscape evolution. Unfortunately, irreversible coastal land loss in this region poses a threat to native, industrial, scientific, and military communities. The Arctic coastline is vast, spanning more than 100,000 km across eight nations, ten percent of which is overseen by the United States. Much of area is inaccessible by all-season roads. People and infrastructure, therefore, are commonly located near the coast. The impact of the Arctic coastal erosion problem is widespread. Homes are being lost. Residents are being dispersed and their villages relocated. Shoreline fuel storage and delivery systems are at greater risk. The U.S. Department of Energy (DOE) and Sandia National Laboratories (SNL) operate research facilities along some of the most rapidly eroding sections of coast in the world. The U.S. Department of Defense (DOD) is struggling to fortify coastal radar sites, operated to ensure national sovereignty in the air, against the erosion problem. Rapid alterations to the Arctic coastline are facilitated by oceanographic and geomorphic perturbations associated with climate change. Sea ice extent is declining, sea level is rising, sea water temperature is increasing, and permafrost state is changing. The polar orientation of the Arctic exacerbates the magnitude and rate of the environmental forcings that facilitate coastal land area loss. The fundamental mechanics of these processes are understood; their non-linear combination poses an extreme hazard. Tools to accurately predict Arctic coastal erosion do not exist. To obtain an accurate predictive model, a coupling of the influences of

Hydrophobic Sand Is a Non-Toxic Method of Urine Collection, Appropriate for Urinary Metal Analysis in the Rat

Directory of Open Access Journals (Sweden)

Jessica F. Hoffman

2017-10-01

Full Text Available Hydrophobic sand is a relatively new method of urine collection in the rodent, comparable to the established method using a metabolic cage. Urine samples are often used in rodent research, especially for biomarkers of health changes after internal contamination from embedded metals, such as in a model of a military shrapnel wound. However, little research has been done on the potential interference of hydrophobic sand with urine metal concentrations either by contamination from the sand particulate, or adsorption of metals from the urine. We compare urine collected from rats using the metabolic cage method and the hydrophobic sand method for differences in metal concentration of common urinary metals, and examine physical properties of the sand material for potential sources of contamination. We found minimal risk of internal contamination of the rat by hydrophobic sand, and no interference of the sand with several common metals of interest (cobalt, strontium, copper, and manganese, although we advise caution in studies of aluminum in urine.

Longshore sediment transport at Golden Sands (Bulgaria

Directory of Open Access Journals (Sweden)

Hristo Nikolov

2006-09-01

Full Text Available The paper presents the results of studies on the qualitative and quantitative features of the littoral drift at Golden Sands (Bulgaria, carried out jointly by Polish and Bulgarian researchers. The mathematical modelling of physical coastal processes took wave transformation (wave diffraction and refraction; the effects of shoaling and wave breaking and longshore sediment transport into account. The computations were carried out for the mean statistical annual wave climate, determined on the basis of IO BAS wave data, simulated using the WAM method from long-term Black Sea wind data. The results of sediment transport computations clearly show that its direction off the Golden Sands shore is from north to south.

The use of radionuclide techniques in soil erosion studies

International Nuclear Information System (INIS)

Bernard, C.; Mabit, L.

2006-01-01

Erosion is of concern since it can reduce soil productivity as a result of exportation of inorganic and organic material and nutrients out of the cultivated fields. These are the so-called 'onsite' impacts of erosion. Some of the exported materials, and the associated elements, find their way to water bodies The result is a degradation of the water quality due to suspended solids, sedimentation, eutrophication and pesticide toxicity, what is currently referred to as off-site impacts. Despite its importance, many countries lack reliable and comprehensive data on the problem, its magnitude and spatial extent. One of the reasons is that producing representative and reliable data on erosion is a long and resource intensive process.Fallout radionuclides (FRNs), such as 137 Cs, 210 Pb and 7 Be, have proven to be very powerful tracers of soil movements, that can complement interestingly more conventional approaches. Starting in the mid-1990's the IAEA has been actively involved in supporting coordinated research activities to further develop several methodological aspects related to the use of these isotopes and in the dissemination of the techniques among Member States, through the joint efforts of the Soil and Water Management and Crop Nutrition Section (SWMCN) of the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture and the Soil Science Unit (SSU) of the FAO/IAEA Agriculture and Biotechnology Laboratory. A first Coordinated Research Project (CRP), from 1996 to 2001, helped to test and validate the basic assumptions underlying the use of FRN, to accelerate the development of conversion models used to translate FRN data into soil movements and to evaluate the effect of specific land use management on soil erosion. A second CRP, planned for 2003-2007, builds on the results of the first one to assess the efficiency of different soil conservation practices, to continue the validation of conversion models and the development of user-friendly software to

[Research on Oil Sands Spectral Characteristics and Oil Content by Remote Sensing Estimation].

Science.gov (United States)

You, Jin-feng; Xing, Li-xin; Pan, Jun; Shan, Xuan-long; Liang, Li-heng; Fan, Rui-xue

2015-04-01

Visible and near infrared spectroscopy is a proven technology to be widely used in identification and exploration of hydrocarbon energy sources with high spectral resolution for detail diagnostic absorption characteristics of hydrocarbon groups. The most prominent regions for hydrocarbon absorption bands are 1,740-1,780, 2,300-2,340 and 2,340-2,360 nm by the reflectance of oil sands samples. These spectral ranges are dominated by various C-H overlapping overtones and combination bands. Meanwhile, there is relatively weak even or no absorption characteristics in the region from 1,700 to 1,730 nm in the spectra of oil sands samples with low bitumen content. With the increase in oil content, in the spectral range of 1,700-1,730 nm the obvious hydrocarbon absorption begins to appear. The bitumen content is the critical parameter for oil sands reserves estimation. The absorption depth was used to depict the response intensity of the absorption bands controlled by first-order overtones and combinations of the various C-H stretching and bending fundamentals. According to the Pearson and partial correlation relationships of oil content and absorption depth dominated by hydrocarbon groups in 1,740-1,780, 2,300-2,340 and 2,340-2,360 nm wavelength range, the scheme of association mode was established between the intensity of spectral response and bitumen content, and then unary linear regression(ULR) and partial least squares regression (PLSR) methods were employed to model the equation between absorption depth attributed to various C-H bond and bitumen content. There were two calibration equations in which ULR method was employed to model the relationship between absorption depth near 2,350 nm region and bitumen content and PLSR method was developed to model the relationship between absorption depth of 1,758, 2,310, 2,350 nm regions and oil content. It turned out that the calibration models had good predictive ability and high robustness and they could provide the scientific

Rainfall erosivity map for Ghana

International Nuclear Information System (INIS)

Oduro Afriyie, K.

1995-10-01

Monthly rainfall data, spanning over a period of more than thirty years, were used to compute rainfall erosivity indices for various stations in Ghana, using the Fournier index, c, defined as p 2 /P, where p is the rainfall amount in the wettest month and P is the annual rainfall amount. Values of the rainfall erosivity indices ranged from 24.5 mm at Sunyani in the mid-portion of Ghana to 180.9 mm at Axim in the south western coastal portion. The indices were used to construct a rainfall erosivity map for the country. The map revealed that Ghana may be broadly divided into five major erosion risk zones. The middle sector of Ghana is generally in the low erosion risk zone; the northern sector is in the moderate to severe erosion risk zone, while the coastal sector is in the severe to extreme severe erosion risk zone. (author). 11 refs, 1 fig., 1 tab

Gully erosion in Madagascar: causes and impacts

Science.gov (United States)

Raveloson, Andrea; Székely, Balázs; Visnovitz, Ferenc

2017-04-01

Soil erosion has been recognized as the main cause of land degradation worldwide and gully erosion is currently considered as one of the most impressive and striking erosion type. This global environmental problem has numerous causes (both natural and anthropogenic) and inflict serious socio-economic problems all around the world. The present study aims to discuss the occurrence and environmental issues related to lavakization in Madagascar and its impact on landscape (badland formation), land use management, flora and fauna, infrastructures, soil properties and human life itself. We assembled and reviewed lavaka researches since 1953. Exact location of the field surveys, cited triggering factors and results of these scientific papers have been studied in detail and compared with our data collected using satellite imagery. Lavaka distribution was analyzed using GIS methods and the relation between their density and different factors was studied. An overview of the many contributing factors (climate, topography, geology, vegetation cover, fault systems, tectonism and land use including inappropriate cultivation and irrigation systems) is given in order to better understand lavaka formation, distribution and impacts. Synthesis of previous researches might help us define area susceptible to gully formation. This can be used to determine prevention priorities for farmers, to manage their lands sustainably. This is ILARG contribution 18.

Bedform development in mixed sand-mud: The contrasting role of cohesive forces in flow and bed

Science.gov (United States)

Baas, Jaco H.; Davies, Alan G.; Malarkey, Jonathan

2013-01-01

The majority of subaqueous sediment on Earth consists of mixtures of cohesive clay and cohesionless sand and silt, but the role of cohesion on the development and stability of sedimentary bedforms is poorly understood. The results of new laboratory flume experiments on bedform development in cohesive, mixed sand-mud beds are compared with the results of previous experiments in which cohesive forces in high concentration clay flows dominated bedform development. Even though both series of mixed sand-mud experiments were conducted at similar flow velocities, the textural and structural properties of the bedforms were sufficiently different to permit the designation of key criteria for identifying bedform generation under cohesive flows against bedform generation on cohesive substrates. These criteria are essential for improving bedform size predictions in sediment transport modelling in modern sedimentary environments and for the reconstruction of depositional processes in the geological record. The current ripples developing on the cohesive, mixed sand-mud beds, with bed mud fractions of up to 18%, were significantly smaller than equivalent bedforms in noncohesive sand. Moreover, the bedform height showed a stronger inversely proportional relationship with initial bed mud fraction than the bedform wavelength. This is in contrast with the bedforms developing under the cohesive clay flows, which tend to increase in size with increasing suspended clay concentration until the flow turbulence is fully suppressed. Selective removal of clay from the mixed beds, i.e., clay winnowing, was found to be an important process, with 82-100% clay entrained into suspension after 2 h of bedform development. This winnowing process led to the development of a sand-rich armouring layer. This armouring layer is inferred to have protected the underlying mixed sand-mud from prolonged erosion, and in conjunction with strong cohesive forces in the bed may have caused the smaller size of the

Quantifying accelerated soil erosion through ecological site-based assessments of wind and water erosion

Science.gov (United States)

This work explores how organising soil erosion assessments using established groupings of similar soils (ecological sites) can inform systems for managing accelerated soil erosion. We evaluated aeolian sediment transport and fluvial erosion rates for five ecological sites in southern New Mexico, USA...

Problems of bentonite rebonding of synthetic system sands in turbine mixers

Directory of Open Access Journals (Sweden)

A. Fedoryszyn

2008-12-01

Full Text Available Turbine (rotor mixers are widely used in foundries for bentonite rebonding of synthetic system sands. They form basic equipment in modern sand processing plants. Their major advantage is the short time of the rebond mixing cycle.Until now, no complete theoretical description of the process of mixing in turbine mixers has been offered. Neither does it seem reasonable to try to adapt the theoretical backgrounds of the mixing process carried out in mixers of other types, for example, rooler mixers [1], to the description of operation of the turbine mixers. Truly one can risk the statement that the individual fundamental operations of mixing in rooler mixers, like kneading, grinding, mixing and thinning, are also performed in turbine mixers. Yet, even if so, in turbine mixers these processes are proceeding at a rate and intensity different than in the roller mixers. The fact should also be recalled that the theoretical backgrounds usually relate to the preparation of sand mixtures from new components, and this considerably restricts the field of application of these descriptions when referred to rebond mixing of the system sand. The fundamentals of the process of the synthetic sand rebonding with bentonite require determination and description of operations, like disaggregation, even distribution of binder and water within the entire volume of the rebonded sand batch, sand grains coating, binder activation and aeration.This study presents the scope of research on the sand rebonding process carried out in turbine mixers. The aim has been to determine the range and specific values of the designing and operating parameters to get optimum properties of the rebonded sand as well as energy input in the process.

The Suitability Of Local Quartz Sand In The Production Of Bath Crucibles.

Directory of Open Access Journals (Sweden)

C. O. Okpanachi

2017-03-01

Full Text Available The suitability of local quartz sand in the production of bath crucibles is a study that was carried out in order to impart overall strength on bath crucibles hence reduce breakages during fettling. Therefore this research constitutes a study to enhance the efficiency of production of bath crucibles by addition of quartz sand in slip preparation. The steps taken in the beneficiation of quartz sand for the production of bath crucibles are comminution which entails crushing and milling classification washing liquid dispersion sizing and reduction of iron content by magnetic separation. The slip contains materials like plastic clay feldspar kaolin talc sodium silicate water quartz sand etc. These were all milled in the ball mill for slip production casting and fettling glazing and sintering to get final bath crucibles as the end products. Quartz sand is used in a variety of products essentially as raw material for the foundry casting and glass industries and also in chemicals water filtration and ceramics the heat resistance nature of quartz sand makes it an excellent refractory substance for these industrial processes. Slip can be prepared for production of bath crucibles without the inclusion of quartz sand however the addition of quartz sand is needed to improve the mechanical performance of the slip in the production of bath crucibles.

Rill erosion rates in burned forests

Science.gov (United States)

Joseph W. Wagenbrenner; Peter R. Robichaud

2011-01-01

Introduction Wildfires often produce large increases in runoff and erosion rates (e.g., Moody and Martin, 2009), and land managers need to predict the frequency and magnitude of postfire erosion to determine the needs for hazard response and possible erosion mitigation to reduce the impacts of increased erosion on public safety and valued resources. The Water Erosion...

Evaluation of the serum zinc level in erosive and non-erosive oral lichen planus.

Science.gov (United States)

Gholizadeh, N; Mehdipour, M; Najafi, Sh; Bahramian, A; Garjani, Sh; Khoeini Poorfar, H

2014-06-01

Lichen planus is a chronic inflammatory immunologic-based disease involving skin and mucosa. This disease is generally divided into two categories: erosive and non-erosive. Many etiologic factors are deliberated regarding the disease; however, the disorders of immune system and the role of cytotoxic T-lymphocytes and monocytes are more highlighted. Zinc is an imperative element for the growth of epithelium and its deficiency induces the cytotoxic activity of T-helper2 cells, which seems to be associated with lichen planus. This study was aimed to evaluate the levels of serum zinc in erosive and non-erosive oral lichen planus (OLP) and to compare it with the healthy control group to find out any feasible inference. A total of 22 patients with erosive oral lichen planus, 22 patients with non erosive OLP and 44 healthy individuals as the control group were recruited in this descriptive-comparative study. All the participants were selected from the referees to the department of oral medicine, school of dentistry, Tabriz University of Medical Sciences. Serum zinc level was examined for all the individuals with liquid-stat kit (Beckman Instruments Inc.; Carlsbad, CA). Data were analyzed by adopting the ANOVA and Tukey tests, using SPSS 16 statistical software. The mean age of patients with erosive and non-erosive LP was 41.7 and 41.3 years, respectively. The mean age of the healthy control group was 34.4 years .The mean serum zinc levels in the erosive and non erosive lichen planus groups and control groups were 8.3 (1.15), 11.15 (0.92) and 15.74 (1.75) μg/dl respectively. The difference was statistically significant (poral lichen planus. This finding may probably indicate the promising role of zinc in development of oral lichen planus.

A Canadian perspective on the supply costs, production and economic impacts from oil sands development

International Nuclear Information System (INIS)

McColl, D.; Masri, M.

2008-01-01

This article provided a synopsis of oil sands research recently conducted at the Canadian Energy Research Institute (CERI). The production profiles and capital expenditures that CERI has projected for oil sands projects were explored along with the macroeconomic benefits associated with oil sands development. In addition to rising capital and operating costs, bitumen producers are challenged by labour shortages and environmental concerns. However, CERI warrants continued growth in production from the oil sands industry, given the current high price state of the global oil market and security of supply concerns from oil importing countries. This article also provided background information and analysis to assess the implications of future development. The projected growth in the oil sands industry creates demands for infrastructure, housing, health care, education, and business services. The economic impacts were measured at the local, provincial, national and global levels in terms of changes in gross domestic product; changes in employment; and, changes in government revenues. It was concluded that with continued investment and development, Alberta's oil sands resource is expected to continue to produce oil for decades, and would eventually achieve 6 MMbpd production. 8 refs., 3 tabs., 10 figs

Utilization of fly ash as partial sand replacement in oil palm shell lightweight aggregate concrete

Science.gov (United States)

Nazrin Akmal, A. Z. Muhammad; Muthusamy, K.; Mat Yahaya, F.; Hanafi, H. Mohd; Nur Azzimah, Z.

2017-11-01

Realization on the increasing demand for river sand supply in construction sector has inspired the current research to find alternative material to reduce the use of natural sand in oil palm shell lightweight aggregate concrete (OPS LWAC) production. The existence of fly ash, a by-product generated from coal power plant, which pose negative impact to the environment when it is disposed as waste, were used in this research. The effect of fly ash content as partial sand replacement towards workability and compressive strength of OPS lightweight aggregate concrete were investigated. Four concrete mixes containing various percentage of fly ash that are 0%, 10%, 20% and 30% by weight of sand were used in the experimental work. All mixes were cast in form of cubes before subjected to water curing until the testing age. Compressive strength test were conducted at 1, 3, 7 and 28 days. The finding shows that the workability of the OPS LWAC decreases when more fly ash are used as sand replacement. It was found that adding of 10% fly ash as sand replacement content resulted in better compressive strength of OPS LWAC, which is higher than the control mix.

Quantification and Evaluation of Soil Erosion in the Estuaries of Cameroon, Gulf of Guinea: Case of Nylon Area

Directory of Open Access Journals (Sweden)

Eric Flavien Mbiakouo-Djomo

2018-01-01

Full Text Available The area of Nylon represents a sensible and vulnerable environment where water erosion is the cause of many soil losses contributing to the production and movement of sediments from the upstream to the lowest depths. The high level of rainfall in this town, soil texture (sand-clay-silt, and the anarchic occupation of the area play a part in the important deterioration of the bare ground on the upstream of the catchment area. This causes with time an instability of structures and living places which can lead to their progressive disappearance. In order to assess the quantities of displaced sediments, the studies on the quantification of soil moved annually by water erosion are carried out. A direct method is used consisting in using a minisimulator of rain (NEME in order to understand the phenomena involved and assess the quantity of sediments which can be moved. It helps in assessing erosion caused by the rain and extrapolating results over the catchment area of the chosen field of study. USLE relation has permit to make an extrapolation of the quantity of soil affected, and the result shows that the average potential of loss of soil is 153.57 t/ha/annum.

Gage for measuring coastal erosion and sedimentation

Science.gov (United States)

Carpini, T. D.; Moughon, W. C.

1970-01-01

Underwater sand height gage, which measures heights up to 12 inches, is comprised of two standard flush-diaphragm pressure transducers. Gage is very sensitive to buried water heights and is useful as a research tool in study of wet earth and landslide phenomena.

Modeling soil erosion in a watershed

OpenAIRE

Lanuza, R.

1999-01-01

Most erosion models have been developed based on a plot scale and have limited application to a watershed due to the differences in aerial scale. In order to address this limitation, a GIS-assisted methodology for modeling soil erosion was developed using PCRaster to predict the rate of soil erosion at watershed level; identify the location of erosion prone areas; and analyze the impact of landuse changes on soil erosion. The general methodology of desktop modeling or soil erosion at watershe...

Western Gas Sands Project: stratigrapy of the Piceance Basin

Energy Technology Data Exchange (ETDEWEB)

Anderson, S. (comp.)

1980-08-01

The Western Gas Sands Project Core Program was initiated by US DOE to investigate various low permeability, gas bearing sandstones. Research to gain a better geological understanding of these sandstones and improve evaluation and stimulation techniques is being conducted. Tight gas sands are located in several mid-continent and western basins. This report deals with the Piceance Basin in northwestern Colorado. This discussion is an attempt to provide a general overview of the Piceance Basin stratigraphy and to be a useful reference of stratigraphic units and accompanying descriptions.

Clean and Secure Energy from Domestic Oil Shale and Oil Sands Resources

Energy Technology Data Exchange (ETDEWEB)

Spinti, Jennifer [Inst. for Clean and Secure Energy, Salt Lake City, UT (United States); Birgenheier, Lauren [Inst. for Clean and Secure Energy, Salt Lake City, UT (United States); Deo, Milind [Inst. for Clean and Secure Energy, Salt Lake City, UT (United States); Facelli, Julio [Inst. for Clean and Secure Energy, Salt Lake City, UT (United States); Hradisky, Michal [Inst. for Clean and Secure Energy, Salt Lake City, UT (United States); Kelly, Kerry [Inst. for Clean and Secure Energy, Salt Lake City, UT (United States); Miller, Jan [Inst. for Clean and Secure Energy, Salt Lake City, UT (United States); McLennan, John [Inst. for Clean and Secure Energy, Salt Lake City, UT (United States); Ring, Terry [Inst. for Clean and Secure Energy, Salt Lake City, UT (United States); Ruple, John [Inst. for Clean and Secure Energy, Salt Lake City, UT (United States); Uchitel, Kirsten [Inst. for Clean and Secure Energy, Salt Lake City, UT (United States)

2015-09-30

This report summarizes the significant findings from the Clean and Secure Energy from Domestic Oil Shale and Oil Sands Resources program sponsored by the Department of Energy through the National Energy Technology Laboratory. There were four principle areas of research; Environmental, legal, and policy issues related to development of oil shale and oil sands resources; Economic and environmental assessment of domestic unconventional fuels industry; Basin-scale assessment of conventional and unconventional fuel development impacts; and Liquid fuel production by in situ thermal processing of oil shale Multiple research projects were conducted in each area and the results have been communicated via sponsored conferences, conference presentations, invited talks, interviews with the media, numerous topical reports, journal publications, and a book that summarizes much of the oil shale research relating to Utah’s Uinta Basin. In addition, a repository of materials related to oil shale and oil sands has been created within the University of Utah’s Institutional Repository, including the materials generated during this research program. Below is a listing of all topical and progress reports generated by this project and submitted to the Office of Science and Technical Information (OSTI). A listing of all peer-reviewed publications generated as a result of this project is included at the end of this report; Geomechanical and Fluid Transport Properties 1 (December, 2015); Validation Results for Core-Scale Oil Shale Pyrolysis (February, 2015); and Rates and Mechanisms of Oil Shale Pyrolysis: A Chemical Structure Approach (November, 2014); Policy Issues Associated With Using Simulation to Assess Environmental Impacts (November, 2014); Policy Analysis of the Canadian Oil Sands Experience (September, 2013); V-UQ of Generation 1 Simulator with AMSO Experimental Data (August, 2013); Lands with Wilderness Characteristics, Resource Management Plan Constraints, and Land Exchanges

Progress of nuclide tracing technique in the study of soil erosion in recent decade

International Nuclear Information System (INIS)