Littérature scientifique sur le sujet « Sediment transfert »
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Articles de revues sur le sujet "Sediment transfert"
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Frenette, M., et P. Y. Julien. « LAVSED-I — Un modèle pour prédire l'érosion des bassins et le transfert de sédiments fins dans les cours d'eau nordiques ». Canadian Journal of Civil Engineering 13, no 2 (1 avril 1986) : 150–61. http://dx.doi.org/10.1139/l86-023.
Texte intégralRésumé :
Computer modeling techniques are used for predicting soil losses from overland flow and subsequent suspended sediment yield from large watersheds. The model LAVSED-I (LAVal SEDidentological model No. 1) is based on the universal soil-loss equation of Wischmeier and Smith and the equation of Kiline and Richardson. The model subdivides the watershed into square units varying in size from 0.3 to 3000 km2 and the computational procedure is subdivided in four components: precipitation, physical characteristics of watersheds, erosion/sedimentation, and land use. This paper describes the operational development and the application of the model to a prototype-scale watershed. A map for the annual soil loss is presented for the Chaudière watershed (area = 5830 km2). Results of mapping compared with the sediment yield observed are shown in the paper.
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Subardjo, Petrus, Agus Anugroho Dwi Suryoputro et Ibnu Praktikto. « Sebaran Sedimen Tersuspensi di Perairan Teluk Awur Jepara menggunakan Citra Landsat 8 ». Buletin Oseanografi Marina 9, no 1 (24 avril 2020) : 77–82. http://dx.doi.org/10.14710/buloma.v9i1.29111.
Texte intégralRésumé :
Sedimen tersuspensi dianggap sebagai sedimen yang didistribusikan oleh arus laut. Arus sepanjang pantai (longshore current) berperan besar terhadap proses perpindahan sedimen di perairan. Gelombang laut yang yang membentuk sudut terhadap garis pantai menyebabkan arus sepanjang pantai Transpor sedimen yang disebabkan oleh arus sepanjang panti sering menimbulkan permasalahan erosi pantai dan pendangkalan perairan. Perairan Teluk Awur memiliki bentuk teluk dan tanjung yang memungkinkan terjadinya arus sepanjang pantai. Potensi adanya proses erosi dan sedimentasi di perairan Teluk Awur membuat pentingnya kajian mengenai pola sebaran sedimen tersuspensi. Penelitian ini mampu menjelaskan tentang pola sebaran sedimen tersuspensi di perairan Teluk Awur, Kecamatan Tahunan, Kabupaten Jepara. Metode yang digunakan untuk penentuan sedimen tersuspensi menggunakan pengindraan jauh dan data yang digunakan yaitu citra satelit landsat-8. Kandungan sedimen tersuspensi tertinggi berada di Desa Teluk Awur dan Desa Demaan. Kandungan tertinggi sebesar ± 67,54 mg/L dan semakin menjauhi pantai konsentrasi menurun. Tingginya kadungan sedimen tersuspensi dipengaruhi oleh proses mixing dan intensitas curah hujan. Suspended sediments are considered as sediments distributed by ocean currents. Current along the coast (longshore current) plays a major role in the process of transfer of sediment in the waters. Sea waves that form angles to the coastline cause currents along the coast Sediment transport caused by currents along the orphanage often cause erosion and coastal silting problems. The waters of Teluk Awur have the shape of bays and headlands which allow currents along the coast. The potential for erosion and sedimentation in the Awur Bay waters makes it important to study the pattern of suspended sediment distribution. This research is able to explain the pattern of suspended sediment distribution in Awur Bay waters, Annual District, Jepara Regency. The method used to determine suspended sediment uses remote sensing and the data used are Landsat-8 satellite imagery. The highest suspended sediment content was in Teluk Awur Village and Demaan Village. The highest content of ± 67.54 mg / L and increasingly away from the beach decreased concentration. The high suspended sediment content is influenced by the mixing process and the intensity of rainfall.
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Gude, Martin, Christer Jonasson, Susanne Dietrich et Dieter Scherer. « Assessment of Variability in Fluvial Sediment Transfers in Kärkevagge (N-Sweden) during the last 50 Years ». Hydrology Research 31, no 4-5 (1 août 2000) : 373–84. http://dx.doi.org/10.2166/nh.2000.0022.
Texte intégralRésumé :
The Kärkevagge (Abisko area, Northern Sweden) represents a focus research basin concerning geomorphic processes and sediment budgets for the last 50 years. Different geomorphic process studies provide comparative data sets concerning climate variability implications on sediment transfers. While monitoring of sediment transfers is discontinuous with respect to study periods and methods, a detailed chronology of high-magnitude events with significant sediment displacement is available. In continuation of these studies, investigations in 1995 and 1998 as part of the MOSAIC project (Modelling Of Snowmelt And Its Consequences) are concentrating on snowmelt-induced slushflow initiation and transports of sediments in several small headwater catchments during the snowmelt period. Main purpose of the investigations is to characterize different catchment sections in terms of their hydrologic and sedimentologic contribution to the total fluvial and sediment budget of the basin, and to evaluate their specific sensitivity related to changes in atmospheric boundary conditions. By means of these data sets, the temporal variability of fluvial sediment transfers can be assessed over different time scales. The paper focuses on a description of different sections in the fluvial sediment transfer system in Kärkevagge. By comparing results from recent field investigations with data from former studies, the significance of rainfall- and snowmelt-triggered events for sediment transfers is evaluated.
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Cutter, Leah, Kevin R. Sowers et Harold D. May. « Microbial Dechlorination of 2,3,5,6-Tetrachlorobiphenyl under Anaerobic Conditions in the Absence of Soil or Sediment ». Applied and Environmental Microbiology 64, no 8 (1 août 1998) : 2966–69. http://dx.doi.org/10.1128/aem.64.8.2966-2969.1998.
Texte intégralRésumé :
ABSTRACT Bacterial enrichment cultures developed with Baltimore Harbor (BH) sediments were found to reductively dechlorinate 2,3,5,6-tetrachlorobiphenyl (2,3,5,6-CB) when incubated in a minimal estuarine medium containing short-chain fatty acids under anaerobic conditions with and without the addition of sediment. Primary enrichment cultures formed both meta and orthodechlorination products from 2,3,5,6-CB. The lag time preceding dechlorination decreased from 30 to less than 20 days as the cultures were sequentially transferred into estuarine medium containing dried, sterile BH sediment. In addition, only ortho dechlorination was observed following transfer of the cultures. Sequential transfer into medium without added sediment also resulted in the development of a strict ortho-dechlorinating culture following a lag of more than 100 days. Upon further transfer into the minimal medium without sediment, the lag time decreased to less than 50 days. At this stage all cultures, regardless of the presence of sediment, would produce 2,3,5-CB and 3,5-CB from 2,3,5,6-CB. The strictortho-dechlorinating activity in the sediment-free cultures has remained stable for more than 1 year through several transfers. These results reveal that the classical microbial enrichment technique using a minimal medium with a single polychlorinated biphenyl (PCB) congener selected for ortho dechlorination of 2,3,5,6-CB. Furthermore, this is the first report of sustained anaerobic PCB dechlorination in the complete absence of soil or sediment.
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Cogez, Antoine, Frédéric Herman, Éric Pelt, Thierry Reuschlé, Gilles Morvan, Christopher M. Darvill, Kevin P. Norton, Marcus Christl, Lena Märki et François Chabaux. « U–Th and <sup>10</sup>Be constraints on sediment recycling in proglacial settings, Lago Buenos Aires, Patagonia ». Earth Surface Dynamics 6, no 1 (5 mars 2018) : 121–40. http://dx.doi.org/10.5194/esurf-6-121-2018.
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Abstract. The estimation of sediment transfer times remains a challenge to our understanding of sediment budgets and the relationships between erosion and climate. Uranium (U) and thorium (Th) isotope disequilibria offer a means of more robustly constraining sediment transfer times. Here, we present new uranium and thorium disequilibrium data for a series of nested moraines around Lago Buenos Aires in Argentine Patagonia. The glacial chronology for the area is constrained using in situ cosmogenic 10Be analysis of glacial outwash. Sediment transfer times within the periglacial domain were estimated by comparing the deposition ages of moraines to the theoretical age of sediment production, i.e., the comminution age inferred from U disequilibrium data and recoil loss factor estimates. Our data show first that the classical comminution age approach must include weathering processes accounted for by measuring Th disequilibrium. Second, our combined data suggest that the pre-deposition history of the moraine sediments is not negligible, as evidenced by the large disequilibrium of the youngest moraines despite the equilibrium of the corresponding glacial flour. Monte Carlo simulations suggest that weathering was more intense before the deposition of the moraines and that the transfer time of the fine sediments to the moraines was on the order of 100–200 kyr. Long transfer times could result from a combination of long sediment residence times in the proglacial lake (recurrence time of a glacial cycle) and the remobilization of sediments from moraines deposited during previous glacial cycles. 10Be data suggest that some glacial cycles are absent from the preserved moraine record (seemingly every second cycle), supporting a model of reworking moraines and/or fluctuations in the extent of glacial advances. The chronological pattern is consistent with the U–Th disequilibrium data and the 100–200 kyr transfer time. This long transfer time raises the question of the proportion of freshly eroded sediments that escape (or not) the proglacial environments during glacial periods.
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Burd, Brenda J., Christopher J. Lowe et Carmen Morales-Caselles. « Uptake of PCBs into sediment dwellers and trophic transfer in relation to sediment conditions in the Salish Sea ». FACETS 7 (1 janvier 2022) : 936–65. http://dx.doi.org/10.1139/facets-2021-0032.
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We examined uptake of polychlorinated biphenyls (PCBs) into various marine sediment feeders relative to physical and geochemical factors and transfer to higher trophic levels. PCBs exceeding Canadian Council Ministers of the Environment Guidelines by 6–55× were found in industrialized harbours and some near-outfall sediments, indicating ongoing land input. Sediment PCBs were correlated with organic flux and content. Tissue PCBs were >10× sediment PCBs in all samples and highest in Victoria Harbour infauna, suggesting considerable uptake from these extremely contaminated, organically enriched, chronically disturbed sediments. Sediment PCBs were the primary predictor of tissue lipid PCBs followed by %fines. This results in generally higher tissue PCBs in more depositional regions. The lipid/sediment PCBs (uptake rate) declined with increasing sediment PCBs, acid volatile sulfides and benthos biomass turnover. PCB homologue composition did not change with uptake from sediments or at higher trophic levels, suggesting minimal metabolization in tissues. Trophic bio-magnification occurs since lipid PCBs were 2–100× higher in seal blubber than sediment feeders. PCBs were compared with polybrominated diphenyl ethers (PBDEs) for the same samples. PCBs were highest in industrialized harbours, whereas PBDEs were elevated in harbours but highest near wastewater discharges. This reflects differences in usage history, sediment dynamics, and affinities. PCBs appear to be more bio-accumulative and persistent at higher trophic levels than PBDEs.
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Hull, Erin A., Rebekah R. Stiling, Marco Barajas, Rebecca B. Neumann, Julian D. Olden et James E. Gawel. « Littoral sediment arsenic concentrations predict arsenic trophic transfer and human health risk in contaminated lakes ». PLOS ONE 18, no 10 (19 octobre 2023) : e0293214. http://dx.doi.org/10.1371/journal.pone.0293214.
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Lake sediments store metal contaminants from historic pesticide and herbicide use and mining operations. Historical regional smelter operations in the Puget Sound lowlands have resulted in arsenic concentrations exceeding 200 μg As g-1 in urban lake sediments. Prior research has elucidated how sediment oxygen demand, warmer sediment temperatures, and alternating stratification and convective mixing in shallow lakes results in higher concentrations of arsenic in aquatic organisms when compared to deeper, seasonally stratified lakes with similar levels of arsenic pollution in profundal sediments. In this study we examine the trophic pathways for arsenic transfer through the aquatic food web of urban lakes in the Puget Sound lowlands, measuring C and N isotopes–to determine resource usage and trophic level–and total and inorganic arsenic in primary producers and primary and secondary consumers. Our results show higher levels of arsenic in periphyton than in other primary producers, and higher concentrations in snails than zooplankton or insect macroinvertebrates. In shallow lakes arsenic concentrations in littoral sediment are similar to deep profundal sediments due to arsenic remobilization, mixing, and redeposition, resulting in direct arsenic exposure to littoral benthic organisms such as periphyton and snails. The influence of littoral sediment on determining arsenic trophic transfer is evidenced by our results which show significant correlations between total arsenic in littoral sediment and total arsenic in periphyton, phytoplankton, zooplankton, snails, and fish across multiple lakes. We also found a consistent relationship between percent inorganic arsenic and trophic level (determined by δ15N) in lakes with different depths and mixing regimes. Cumulatively, these results combine to provide a strong empirical relationship between littoral sediment arsenic levels and inorganic arsenic in edible species that can be used to screen lakes for potential human health risk using an easy, inexpensive sampling and analysis method.
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Brydon, Julia, Iwata Oh, Julie Wilson, Ken Hall et Hans Schreier. « Evaluation of Mitigation Methods to Manage Contaminant Transfer in Urban Watersheds ». Water Quality Research Journal 44, no 1 (1 février 2009) : 1–15. http://dx.doi.org/10.2166/wqrj.2009.002.
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Abstract Three case studies on trace metal contamination in urban stormwater are presented from the Greater Vancouver area of British Columbia. In the first case study, the spatial and temporal variability in trace metals in sediments were determined in the completely urbanized Brunette watershed. A natural lake in the middle of the watershed acts as a sediment detention system, and an analysis of the sediment core showed the historic accumulation of metal and selective organic contaminants in sediments since the early 1800s. Suspended sediments transported during storm events showed significantly higher concentrations of trace metals than bedload sediments, and the largest proportion of the geochemically active metals was found to be associated with the organic-sulphur-based fraction. Benthic organism survival tests showed mixed results with lower survival and growth in urban sediments than in control sediments from a forested watershed. In the second case study, significant correlations were obtained between percent impervious cover and trace metal concentrations in 28 subwatersheds with various degrees of urbanization. It is shown that imperviousness combined with traffic density can significantly improve the prediction of metal contamination in highly urbanized watersheds. In the third case study five urban stormwater detention systems were examined over one year to determine how effective these systems were in removing metal contamination. The results were highly variable depending on a wide range of physical conditions, land use activities, traffic volume, and detention system designs. The range of total metal detention was between −15 to +72% for copper (Cu), lead (Pb), and zinc (Zn), while iron (Fe) and manganese (Mn) retention was generally poor. Labile Zn was more effectively retained in four of the five ponds, and a significant relationship was found between percent imperviousness, traffic volume, and Zn concentrations in water, sediment, and labile form.
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Searcy, Kristin E., Aaron I. Packman, Edward R. Atwill et Thomas Harter. « Deposition of Cryptosporidium Oocysts in Streambeds ». Applied and Environmental Microbiology 72, no 3 (mars 2006) : 1810–16. http://dx.doi.org/10.1128/aem.72.3.1810-1816.2006.
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ABSTRACT The transfer of Cryptosporidium oocysts from the surface water to the sediment beds of streams and rivers influences their migration in surface waters. We used controlled laboratory flume experiments to investigate the deposition of suspended Cryptosporidium parvum oocysts in streambeds. The experimental results demonstrate that hydrodynamic interactions between an overlying flow and a sediment bed cause oocysts to accumulate in the sediments and reduce their concentrations in the surface water. The association of C. parvum with other suspended sediments increased both the oocysts' effective settling velocity and the rate at which oocysts were transferred to the sediment bed. A model for the stream-subsurface exchange of colloidal particles, including physical transport and physicochemical interactions with sediment grains, accurately represented the deposition of both free C. parvum oocysts and oocysts that were attached to suspended sediments. We believe that these pathogen-sediment interactions play an important role in regulating the concentrations of Cryptosporidium in streams and rivers and should be taken into consideration when predicting the fate of pathogens in the environment.
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Lau, Maximilian P., Michael Sander, Jörg Gelbrecht et Michael Hupfer. « Spatiotemporal redox dynamics in a freshwater lake sediment under alternating oxygen availabilities : combined analyses of dissolved and particulate electron acceptors ». Environmental Chemistry 13, no 5 (2016) : 826. http://dx.doi.org/10.1071/en15217.
Texte intégralRésumé :
Environmental contextAt sediment surfaces, the availability of oxygen is controlled by its downward transport from the water surface and its consumption in microbial metabolism. Microorganisms can also consume substances other than oxygen to dispose of the surplus charge that is generated during microbial metabolism. We investigate the complex dynamics of these other substances when the oxygen availability fluctuates, and thereby contribute to the mechanistic understanding of oxygen-consuming processes in aquatic environments. AbstractBenthic mineralisation in lakes largely controls the availability of oxygen in the water column above the sediment. In stratified lakes with anoxic hypolimnetic waters, mineralisation proceeds by anaerobic respiration using terminal electron acceptors (TEAs) other than O2. In past work, hypolimnetic oxygen consumption has been estimated from vertical concentration profiles of redox-active dissolved species in the water column and the underlying sediment. Electron transfer to and from particulate mineral and organic phases in the sediments was, however, not accounted for, mainly because of methodological constraints. In this work we use an electrochemical approach, mediated electrochemical analysis, to directly quantify changes in the redox states of particulate geochemical phases in a lake sediment. In mesocosm incubations, sediments were subjected to shifting oxygen availability similar to conditions during and after lake overturn events. The temporal redox dynamics of both dissolved and particulate phases in sediments were monitored at a high spatial resolution. We used a combination of experimental and modelling approaches to couple the observed changes in the redox state of dissolved and particulate species in the sediment to the oxygen turnover in the overlying water column. For the studied freshwater sediment, the amount of O2 consumed during the re-oxidation of these phases in the top 21mm of the sediment after switching from hypoxic to oxic conditions corresponded to ~50% of the total sediment oxygen consumption that was estimated from in-lake measurements after the onset of summer stratification. We found that solid phases in the sediments play a more profound role in electron accepting processes than previously considered. Based on these results, we propose that the herein presented analytical method offers the possibility to constrain parameters in theoretical models that simulate benthic redox dynamics including the electron transfer to and from geochemical phases in the sediments.
Thèses sur le sujet "Sediment transfert"
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Taccone, Florent. « Modélisation numérique du transfert sédimentaire en bassin versant montagneux fortement érodable ». Thesis, Paris Est, 2018. http://www.theses.fr/2018PESC1040/document.
Texte intégralRésumé :
Dans certains petits bassins versants de montagne, des évènements de pluie extrême peuvent engendrer de forts exports sédimentaires. Ce volume important de sédiment peut avoir un impact sur la gestion des ouvrages hydrauliques à l’aval de ces bassins. Aujourd’hui, pour représenter les processus d’érosion à l’échelle du bassin versant, des modèles conceptuels distribués sont majoritairement utilisés (CASC2D, SHETRAN, DWSM). Ces modèles sont basés sur des formules d’érosion globales et sont validés pour des maillages grossiers (> 30 m). D’un autre côté, il existe des modèles capables de représenter finement des processus d’érosion gravitaire, par des écoulements multiphasiques, principalement utilisés sur des cas à petite échelle. Ce travail de thèse propose le développement d’un modèle à base physique capable de représenter à la fois les transferts hydrauliques et l’hydrologie des bassins versants, les processus d’érosion gravitaire et de reprise/dépôt des sédiments dans le réseau hydraulique. Cela permettra de quantifier l’export sédimentaire à l’exutoire d’un bassin pour des tempêtes extrêmes, d’identifier des zones de fortes productions sédimentaires et des dynamiques de stockage des sédiments dans le réseau hydraulique afin d’aider à la gestion des bassins versants. Il s’agit dans un premier temps d’évaluer la résolution des équations de Saint-Venant pour du ruissellement avec des faibles hauteurs d’eau sur des fortes pentes. Pour diagnostiquer les différents schémas numériques que l’on peut trouver dans la littérature, un cas test, disposant d’une solution analytique des équations de Saint-Venant, représentant, un canal rectiligne sur lequel tombe une pluie constante est utilisé. Ce cas test comporte une zone sèche à l’amont et permet d’évaluer les propriétés clés qu’un schéma doit comporter pour représenter le ruissellement sur un bassin versant, à savoir la positivité des hauteurs d’eau, la transition entre zones sèches et mouillées, l’équilibre du lac au repos et la non limitation de la pente. Le schéma de Chen et Noelle (2017) est finalement choisi. Ensuite, avec l’ajout d’une loi d’infiltration de type Green-Ampt (1911), le modèle sera évalué dans sa capacité à représenter les hydrogrammes en sortie, mais surtout les vitesses locales d’écoulement sur des bassins versants réels. Pour cela, on évalue la part d’erreur provenant de la résolution numérique et de la modélisation physique du frottement de l’eau sur le fond au travers de quatre cas expérimentaux de l’échelle du laboratoire à un bassin de 1 km².Un modèle d’érosion gravitaire, basé sur les critères de détachement et de dépôt de Takahashi (2009), est couplé au modèle d’hydraulique global par une équation d’évolution du fond. L’évolution du stock de sédiment dans le réseau hydraulique est modélisée à l’aide d’une équation d’advection représentant les sédiments en suspension dans l’écoulement. Les lois classiques de dépôts de d’érosion de Krone et Parthéniades sont utilisées pour la reprise dépôt des sédiments dans le réseau.Le modèle d’érosion est ensuite validé sur le bassin versant du Laval (86 ha), instrumenté et surveillé par l’ORE Draix-Bléone, sur plusieurs évènements très érosifs. Le modèle est enfin appliqué à deux bassins non instrumentés mais à enjeu pour EDF, pour une étude de dimensionnement d’ovoïdes dans la vallée de la DuranceIn some small mountain catchments, extreme rainfall events can lead to strong sediment exports. This large volume of sediment can have an impact on the management of hydraulic structures downstream these basins. Today, to represent erosion processes on a watershed scale, distributed conceptual models are mainly used (CASC2D, SHETRAN, DWSM). These models are based on global erosion formulas and are validated for coarse mesh sizes (> 30 m). On the other hand, there are models capable of finely representing gravity erosion processes, by multiphase flows, mainly used on small-scale cases. This thesis work proposes the development of a physics-based model capable of representing both hydraulic transfers and watershed hydrology, gravity-driven erosion processes and sediment erosion/deposition in the hydraulic network. This will quantify sediment export at the outlet of a basin for extreme events, identify areas of high sediment production and sediment storage dynamics in the hydraulic network to facilitate watershed management. The first step is to evaluate the resolution of the Saint-Venant equations for run off with low water depths on steep slopes. To diagnose the different numerical schemes that can be found in the literature, a test case, with an analytical solution of the Saint-Venant equations, representing a straight channel on which a constant rain falls is used. This test case includes a dry zone upstream and allows the evaluation of the key properties that a scheme must include to represent runoff over a watershed, such as positive water depths, the transition between dry and wet zones, the balance of the lake at rest and the non-limitation of the slope. The Chen and Noelle (2017) scheme is finally chosen.Then, with the addition of a Green-Ampt infiltration law (1911), the model will be evaluated in its ability to represent output hydrographs, but especially local flow velocities over real watersheds. For this, we evaluate the part of error coming from the numerical resolution and the physical modeling of the friction of the water on the bottom through four experimental cases from the laboratory scale to a basin of 1 km².A gravity erosion model, based on Takahashi's (2009) detachment and deposition criteria, is coupled to the global hydraulic model by a bottom evolution equation. The evolution of the sediment stock in the hydraulic network is modeled using an advection equation representing suspended sediments in the flow. The classic laws of Krone and Parthenades erosion and deposition are used for the recovery sediment deposition in the network.The erosion model is then validated on the Laval watershed (86 ha), instrumented and monitored by the ORE Draix-Bléone, on several very erosive events. Finally, the model is applied to two basins that are not instrumented but are of interest to EDF, for an ovoid dimensioning study in the Durance valley. Translated with www.DeepL.com/Translator
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Bertin, Delphine. « Transfert des composés perfluorés des sédiments aux invertébrés benthiques ». Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10274.
Texte intégralRésumé :
L'accumulation de composés persistants dans le biote constitue des préoccupations écologiques, sanitaires et réglementaires. Parmi ces substances, les composés per- et polyfluorés (PFASs) représentent un cas d'intérêt, en raison de leurs propriétés physico-chimiques particulières. Ces dernières rendent le comportement des PFASs dans l'environnement difficilement prévisibles, les outils actuels n'étant pas adaptés. Bien qu'il soit reconnu que ces composés sont persistants et s'accumulent dans le biote, de nombreuses inconnues subsistent, notamment sur les mécanismes de transferts sédiment–biote et des facteurs qui les contrôlent. Ce travail de thèse aborde le rôle du sédiment dans les processus d'accumulation, et plus particulièrement (a) les voies d'exposition du biote, (b) le rôle de la diversité biologique dans l'accumulation, par l'exposition de deux invertébrés benthiques (Chironomus riparius et gammarus sp.) à du sédiment naturel. La description des cinétiques d'accumulation et d'élimination des PFASs ont mis en évidence la biodisponibilité des composés pour les organismes. Ainsi, un modèle de bioaccumulation en accord avec la croissance des organismes et des particularités des composés a permis d'estimer des constantes d'accumulation et de dépuration (ku et ke). Une représentation conceptuelle du transfert des composés, a permis de comprendre les principales voies de contamination des organismes. D'autre part, la variabilité interspécifique a été évaluée par la comparaison de la bioaccumulation et des voies de transfert des PFASs chez ces deux invertébrés. Ce travail de thèse aura alors permis d'ouvrir de nombreuses questions, notamment celles du rôle du biofilm et de la bioturbation des organismes dans la bioaccumulation et ouvre les perspectives quant à l'étude de la bioamplificationThe accumulation of persistent compounds in biota creates environmental, health and regulatory concerns. Among these substances, the poly-fluorinated compounds (PFASs) represents a case of interest due to their specific physicochemical properties. So the PFAs behavior in the environment is difficult to predict as the existing tools are not suitable. Athough it is recognized that these compounds are persistent and accumulate in biota, many knowledge gaps remain, including the mechanisms of sediment-biota transfer and the factors that control them. This thesis examines the role of sediment in the accumulation process, especially (a) exposure routes of biota, (b) role of biodiversity in the accumulation, by exposing two benthic invertebrates (Chironomus riparius and Gammarus sp.) to natural sediment. The description of PFASs kinetics of accumulation and elimination have showed the biodisponibility of the compounds to organisms. Thus, a bioaccumulation model including the organisms growth and the specificity of the compounds was used to estimate the accumulation and depuration rate constants (ku and ke). A conceptual representation of compounds transfer allowed us to understand the major routes for organisms contamination. Moreover, the interspecific variability has been assessed by comparing the PFASs bioaccumulation and transfer pathways for both invertebrates. This thesis have helped to open up many issues, and especially the influence of both biofilm and organism bioturbation onPFASs bioaccumulation. Moreover some new perspectives on the study of biomagnification were opened
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Chalaux, Thomas. « Impact of decontamination and recultivation of agricultural soils on sediment and radiocaesium transfers in Fukushima rivers ». Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASJ037.
Texte intégralRésumé :
D'importantes quantités de radionucléides (principalement du radiocésium) se sont déposées sur les sols du nord-est du Japon après l'accident de la centrale nucléaire de Fukushima Daiichi en mars 2011. Dès fin 2013, les autorités japonaises ont entrepris un programme sans précédent de décontamination à grande échelle dans les zones cultivées et résidentielles touchées par le panache radioactif (8953 km2). L'objectif principal était de ne pas exposer les habitants à des doses radioactives supérieures à 1 mSv an-1 en plus du niveau naturel, afin de permettre un retour rapide des habitants et la reprise des activités agricoles. Dans ces zones, la décontamination a consisté à décaper sur 5 cm la couche supérieure de sol concentrant le radiocésium (90-99%) et à la remplacer par du sable saprolitique extrait de carrières locales ouvertes à cet effet. Cependant, la décontamination n'a concerné qu'une petite partie du paysage, puisque les terres agricoles couvrent moins de 10 % de cette région. En outre, comme les terres agricoles ont commencé à être remises en culture, de nombreuses questions ont été soulevées quant à l'impact de ces travaux de décontamination sur le transfert du radiocésium dans les rivières et à travers les paysages. Une approche de traçage sédimentaire multi-proxy a été mis en place pour quantifier l'évolution des sources de sédiments et de radiocésium associé aux particules transitant par le système hydrographique drainant le panache radioactif depuis l'accident. Ce grâce à l'analyse combinée de carottes de sédiments et de dépôts de crues fluviales prélevés dans toute la région. En 2021, les autorités japonaises ont annoncé la réouverture potentielle de certaines parties de la zone de retour difficile (Difficult-to-Return zone) à partir du printemps 2023 sans décontamination obligatoire. Les recherches actuelles ont permis de reconstituer et de comparer les sources et les transferts de sédiments et de radiocésium dans trois bassins versants contrastés (barrage de Mano, barrage de Yokokama et barrage de Ogaki) où différents modes de gestion (et calendriers) ont été mis en œuvre. Cela permettra de mieux comprendre l'impact des différentes décisions de gestion et de leur calendrier (décontamination précoce ou tardive) sur les transferts de sédiments et de radiocésium dans ces conditions post-accidentelles uniquesSignificant quantities of radionuclides (mainly radiocesium) were deposited on the soils of Northeastern Japan after the accident of the Fukushima Daiichi Power Plant in March 2011. Starting from late 2013, the Japanese authorities initiated an unprecedented large-scale decontamination programme in cultivated and residential areas affected by the main radioactive plume (8953 km2). The main objective was not to expose local inhabitants to radioactive doses exceeding 1 mSv yr−1 in addition to the natural levels, in order to allow a rapid return of the local inhabitants and the resumption of agricultural activities. In these areas, decontamination consisted of removing the uppermost 5-cm layer of soil that concentrated radiocesium (90-99%) and then replacing it with saprolite sand extracted from local quarries opened for this purpose. Decontamination targeted a minor proportion of the landscape, as farmland covers less than 10% of this region. Furthermore, as agricultural land started to be re-cultivated, many questions were raised regarding the impact of this decontamination work on the transfer of radiocesium into rivers and across landscapes. A multi-proxy sediment tracing approach was designed to quantify the evolution of sources of sediment and particle-bound radiocesium transiting river systems draining the main contamination plume since the accident, through the combined analysis of sediment cores and river flood deposits collected across the region. In 2021, Japanese authorities announced the potential reopening of parts of the Difficult-to-Return zone without obligatory decontamination from Spring 2023 onwards. The current research reconstructed and compared the sources and transfers of sediment and radiocesium in three contrasted catchments (i.e., Mano Dam, Yokokama Dam and Ogaki Dam) where different management modes (and schedules) were implemented. This will shed light into the impact of different management decisions and their timing (early-decontamination or late-decontamination) on sediment and radiocesium transfers in these unique post-accidental conditions
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Gay, Aurore. « Transfert de particules des versants aux masses d'eau sur le bassin Loire-Bretagne ». Thesis, Tours, 2015. http://www.theses.fr/2015TOUR4048/document.
Texte intégralRésumé :
L’érosion et la redistribution des particules détachées représentent un enjeu environnemental, sociétal et économique majeur. Afin de mettre en place des mesures de protection, il est nécessaire d’identifier et quantifier les sources et puits de sédiments ainsi que leur dynamique spatiale et temporelle. L’objectif de cette thèse est donc de dresser le bilan sédimentaire d’un large bassin versant (Loire Bretagne, 155 000 km2) aux paysages contrastés. Sur les versants, les particules détachées issues des différentes sources (érosion diffuse, concentrée, mouvements de masse) représentent un apport de 1.5 * 107 t.an−1 (contribution respective au stock : 82.4%, 12.9%, 4.7%). La prise en compte de la distribution spatiale des processus mis en jeu dans le transfert particulaire et des caractéristiques du site d’étude (ruissellement par saturation en zone de plaine et présence de haies) dans un indice qualitatif permet d’évaluer la connectivité des versants. L’érosion de berge contribue également au stock sédimentaire à hauteur de 6.9 * 105 t.an−1. Au final, seuls 5% des particules détachées, toutes sources confondues, sont transportées jusqu’à l’exutoire du bassin versant et témoignent du fort taux de dépôt au sein du bassin. En parallèle, une valorisation de la base de données des éléments dissous permet de montrer l’importance des flux sédimentaires exportés sous forme dissoute (~ 90% des exports totaux). La représentation de l’ensemble de ces résultats à différentes résolutions spatiales permet de développer une approche qualitative du transfert particulaire et d'identifier les zones à risqueErosion and particles redistribution represent major environmental, societal and economic issues. To adopt protection measures, it is essential to identify and quantify sources and sinks of sediment and their spatial and temporal dynamic. The aim of this work is thus to establish a sediment budget for a large river basin (Loire and Brittany river basin 155,000 km2) with contrasted landscapes. On hillslopes, detached particles from the miscellaneous form of erosion (sheet and rill erosion, gullies and mass movements) represent a supply of 1.5 * 107 t.yr−1 (contribution to the stock of 82.4%, 12.9%, and 4.7% respectively). The consideration of the spatial distribution of processes involved in sediment transport and the characteristics of the study site (soil saturation and presence of hedgerows) in a qualitative landscape-based index allows us to assess the hillslope connectivity. Bank erosion also participates in the sediment budget with 6.9 * 105 t.yr−1 of material provided to the river network. In the end, only 5% of detached particles, from all sources of sediment, reach the basin outlet indicating a substantial deposition on the way from source to outlet. In parallel, the use of the database of dissolved elements allows us to highlight the importance of the dissolved sediment fluxes ( 90% of the total exports of the Loire river). The presentation of all results at different spatial scales permits to provide a qualitative approach of sediment source-to-sink transfers and to identify hotspots of erosion and transfers
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Wu, Yingxin. « Surfactant-Assisted Zerovalent Iron Dechlorination Of Polychlorinated Biphenyl In Contaminated Sediment ». Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0066/document.
Texte intégralRésumé :
La contamination des sols et sédiments par les polychlorobiphényls (PCB) pose un problème sanitaire et environnemental à l’échelle mondiale, en raison de la récalcitrance et de la toxicité de ces composés. L’objectif de cette thèse est de chercher un procédé de remédiation de sédiments contaminés aux PCB en utilisant le fer zérovalent (Fe0). D’abord, une campagne de prélèvement a été menée sur des sites contaminés par le recyclage des déchets électroniques en Chine du sud. La contamination en PCB n’était pas aussi forte que prévue, mais la présence de métaux lourds accentue la difficulté de la remédiation. Ensuite, a été étudiée la déchloration des PCB par le Fe0 en solution aqueuse, en présence de métaux et surfactants. Les résultats ont montré la déchloration progressive des PCB et révélé l’itinéraire réactionnel avec la spécificité des congénères et la régio-spécificité. L’importance relative des facteurs qui influent se classe selon : tensioactif > acide humique > pH > Ni2. La décontamination du sédiment a été étudiée par 1) lavage avec une solution aqueuse de tensioactif suivie de la déchloration des PCB en solution et 2) mélange direct avec le Fe0 et les tensioactifs. La seconde approche s’est avérée prometteuse pour la remédiationSoil and sediment contamination by polychlorinated biphenyls (PCBs) is a global health and environmental concern, since PCBs are toxic and recalcitrant. The aim of this thesis is to find a remediation process to PCBs contaminated sediments by using zerovalent iron (ZVI). To begin the studies on remediation, a survey was conducted on sites contaminated by e-waste recycling activities in south China. PCBs contamination was not as severe as previously, whereas the co-existence of PCBs and heavy metals increases the difficulty of remediation. Afterwards, the feasibility PCBs degradation by ZVI in aqueous solutions was investigated. Results confirmed the stepwise dechlorination of PCBs by ZVI and the major pathway with congener specifity and regiospecifity. The relative importance of the influential factors to ZVI degradation of PCBs was in the order of surfactants > humic acid > pH > Ni2+. Sediment decontamination was studied by 1) washing with an aqueous solution of surfactant followed by ZVI dechlorination of PCBs and 2) direct mixing with ZVI and surfactant solution. The second approach gave promising results for remediation
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Wu, Yingxin. « Surfactant-Assisted Zerovalent Iron Dechlorination Of Polychlorinated Biphenyl In Contaminated Sediment ». Electronic Thesis or Diss., Université de Lorraine, 2016. http://www.theses.fr/2016LORR0066.
Texte intégralRésumé :
La contamination des sols et sédiments par les polychlorobiphényls (PCB) pose un problème sanitaire et environnemental à l’échelle mondiale, en raison de la récalcitrance et de la toxicité de ces composés. L’objectif de cette thèse est de chercher un procédé de remédiation de sédiments contaminés aux PCB en utilisant le fer zérovalent (Fe0). D’abord, une campagne de prélèvement a été menée sur des sites contaminés par le recyclage des déchets électroniques en Chine du sud. La contamination en PCB n’était pas aussi forte que prévue, mais la présence de métaux lourds accentue la difficulté de la remédiation. Ensuite, a été étudiée la déchloration des PCB par le Fe0 en solution aqueuse, en présence de métaux et surfactants. Les résultats ont montré la déchloration progressive des PCB et révélé l’itinéraire réactionnel avec la spécificité des congénères et la régio-spécificité. L’importance relative des facteurs qui influent se classe selon : tensioactif > acide humique > pH > Ni2. La décontamination du sédiment a été étudiée par 1) lavage avec une solution aqueuse de tensioactif suivie de la déchloration des PCB en solution et 2) mélange direct avec le Fe0 et les tensioactifs. La seconde approche s’est avérée prometteuse pour la remédiationSoil and sediment contamination by polychlorinated biphenyls (PCBs) is a global health and environmental concern, since PCBs are toxic and recalcitrant. The aim of this thesis is to find a remediation process to PCBs contaminated sediments by using zerovalent iron (ZVI). To begin the studies on remediation, a survey was conducted on sites contaminated by e-waste recycling activities in south China. PCBs contamination was not as severe as previously, whereas the co-existence of PCBs and heavy metals increases the difficulty of remediation. Afterwards, the feasibility PCBs degradation by ZVI in aqueous solutions was investigated. Results confirmed the stepwise dechlorination of PCBs by ZVI and the major pathway with congener specifity and regiospecifity. The relative importance of the influential factors to ZVI degradation of PCBs was in the order of surfactants > humic acid > pH > Ni2+. Sediment decontamination was studied by 1) washing with an aqueous solution of surfactant followed by ZVI dechlorination of PCBs and 2) direct mixing with ZVI and surfactant solution. The second approach gave promising results for remediation
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Gomez, Delgado Federico. « Processus hydrologiques, écophysiologiques et de transfert de sédiments dans un bassin agroforestier caféier combinant des approches expérimentales et de modélisation pour les besoins des Services Hydrologiques Environnementaux ». Thesis, Montpellier, SupAgro, 2010. http://www.theses.fr/2010NSAM0032/document.
Texte intégralRésumé :
La production hydroélectrique est fortement impactée par la sédimentation dans les retenues de barrages, qui sont influencés par l'occupation du sol, l'infiltration et les interactions entre les eaux de surface et les aquifères. Pour le paiement des Services Hydrologiques Environnementaux au Costa Rica, une quantification de l'impact des utilisations des terres cultivées en café sur le fonctionnement des bassins est nécessaire. Cette thèse vise à : 1) étudier les composantes du bilan hydrologique dans un bassin agroforestier récemment installé 2) à quantifier les flux d'eau et de sédiments à différentes échelles : de la parcelle au bassin et de l'événement de crue à l'échelle annuelle, et 3) à simuler le bilan hydrique et la production de sédiments en tenant compte du ruissellement sur les versants et les routes. Les processus hydrologiques, écophysiologiques et de transfert de sédiments ont été suivis sur le bassin (pluie, débit, évapotranspiration, humidité du sol, niveau de l'aquifère, turbidité) et les parcelles (ruissellement de surface et érosion). Un nouveau modèle éco- hydrologique a été développé pour simuler les termes du bilan hydrologique et de sédiments. Des améliorations sont en cours pour tenir compte de l'effet des routes sur la genèse du ruissellement de surface et de l'érosion. Le faible ruissellement de surface, la faible érosion des parcelles et la faible production de sédiments, compte-tenu des conditions biophysiques et des pratiques de gestion (arbres d'ombrage, désherbage), offrent clairement des Services Ecosystémiques en réduisant les transferts superficiels de pesticides et de sédiments et en permettant une bonne régulation du débit de rivièreThe profitability of hydropower is affected by soil erosion and sedimentation in dam reservoirs, which are influenced by land use, infiltration and aquifer interactions with surface water. In order to promote the payment of Hydrological Environmental Services (HES) in Costa Rica, a quantitative assessment of the impact of land uses (such as coffee farming) on the functioning of drainage basins is required. This thesis seeks: 1) to study the water balance partitioning in a newly installed coffee agroforestry basin 2) to estimate the water and sediment yield at various spatio-temporal scales: from plot to basin and from event to annual scale; and 3) to simulate the water and sediment yields, at both annual and peakflow scale, by including the surface runoff from hillslopes and roads. The main hydrological, ecophysiological and sediment processes were monitored during one year at the basin (rainfall, streamflow, evapotranspiration, soil humidity, aquifer level, turbidity) and at the plots (surface runoff and erosion). A new eco-hydrological model was developed to close the water balance, and the annual sediment yield was also quantified. Improvements are in progress to take into account the effect of roads in surface runoff generation. The low surface runoff, low plot erosion and low basin sediment yield observed under the current biophysical conditions (andisol) and management practices (no tillage, planted trees, bare soil kept by weeding), offer potential HES by reducing the superficial displacement capacity for fertilizers and pesticides, yielding low sediment loads and regulating streamflow variability through highly efficient mechanisms of aquifer recharge-discharge
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Froger, Claire. « Sources et dynamiques spatiales et temporelles des contaminations en éléments traces et hydrocarbures aromatiques polycycliques du continuum atmosphère - sol - rivière d'un bassin versant contrasté ». Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS394/document.
Texte intégralRésumé :
Le développement des activités humaines, notamment industrielles, depuis le 19ième siècle a engendré une contamination massive de l’atmosphère à la rivière, en passant par la biosphère et les sols. Si les contaminations ont fortement diminué depuis la fin des années 1960, elles persistent notamment en milieu urbain, où se concentrent un grand nombre d’activités humaines. Afin de pouvoir gérer au mieux la pollution, il est nécessaire de comprendre la dynamique de transfert des contaminants, ainsi que leurs sources, à l’échelle du continuum atmosphère – sol – rivière. Cette étude a donc pour objectif d’évaluer les variations temporelles et spatiales de deux types de contaminants historiques, les hydrocarbures aromatiques polycycliques (HAP) et certains éléments traces (ET), à l’échelle du bassin versant de l’Orge (950 km2), présentant une urbanisation croissante d’amont en aval. Plusieurs approches ont été utilisées pour tracer les transferts de particules en rivière (radionucléides ⁷Be, ²¹⁰Pb, ¹³⁷Cs), et déterminer les sources de Pb (isotopes du Pb), et les sources de HAP (rapports de molécules).Les résultats ont mis en évidence un impact important des zones urbaines sur la qualité de la rivière Orge en aval du bassin : contamination importante en métaux (Cu, Zn, Sb, Pb) et en HAP de la phase particulaire, et des niveaux élevés en SO42⁻, Na⁺ et Cl⁻, Cu, Zn et Pb dans la phase dissoute. Le traçage des sédiments par les radionucléides a permis d’observer un apport de particules provenant du ruissellement urbain en aval, et d’identifier les particules de route (ou Road Deposited Sediment) comme source principale. Les signatures isotopiques du Pb ainsi que les signatures en HAP permettent de confirmer que le ruissellement urbain est le principal vecteur de contamination. Les estimations des flux d’ET et HAP annuels et saisonniers entrants (retombées atmosphériques) et sortants (exportés par la rivière) ont mis en évidence une accumulation globale à l’échelle du bassin, qui comporte déjà un stock important de contaminants dans ses sols. Cette étude montre ainsi l’importance d’étudier la Zone Critique dans son ensemble afin d’évaluer la dynamique des contaminations au sein et entre ses différents compartiments, et met en évidence l’efficacité du couplage de plusieurs approches afin de comprendre le système entier. Ces résultats pourraient à terme permettre l’établissement d’un modèle de transfert de contaminations au sein d’un bassin urbainThe development of human societies since the 19th century has led to deleterious impacts on the Critical Zone (from atmosphere to river, including biosphere and soils). Despite the decrease of pollutions since the late 1960’s, contaminations remain especially in urban environment, concentrating human activities. To better manage this pollution, it is necessary to understand the dynamics and pathways of contaminants through the atmosphere – soil – river continuum. The goal of this study in thus to evaluate the temporal and spatial variations of two contaminants (polycyclic aromatic hydrocarbons (PAH) and trace elements (TE)) in the Orge River catchment (900 km2, France) being under increasing urban pressure from up to downstream. Several fingerprinting approaches were used to trace sediment dynamics in the river (radionuclides: ⁷Be, ²¹⁰Pb, ¹³⁷Cs), to identify lead sources (lead isotopes) and PAH sources (PAH molecular ratios). The results demonstrated the strong influence of downstream urban areas on the river quality, with an increasing contamination for Cu, Zn, Sb, Pb and PAH in the particulate phase, and for SO42⁻, Na⁺ et Cl⁻, Cu, Zn and Pb in the dissolved phase. The sediment fingerprinting using radionuclides revealed a significant input of particles originating from urban areas and transferred through urban runoff, and identified road deposited sediments as the major source of contaminated particles downstream. Source tracking of Pb and PAH confirmed urban runoff as the main pathway of river contamination. In addition, annual and seasonal PAH and TE fluxes were estimated respectively for the atmospheric inputs, and riverine exports and revealed a global accumulation of contaminant over the catchment, already containing a significant stock of pollutants in its soils. Finally, this study highlights the need to integrate the Critical Zone and the potential of coupling multiples tracking approaches to properly evaluate the contaminant dynamics. These results may be used to establish a model of contaminants transfer in urban catchments
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Morosanu, Gabriela Adina. « La dynamique hydro-sédimentaire du bassin de la rivière Jiu. Approche systèmique et multi-échelles ». Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAU036.
Texte intégralRésumé :
La thèse doctorale intitulée « La dynamique hydro-sédimentaire du bassin versant de la rivière Jiu. Approche systémique et multi-échelle » analyse le transfert des flux liquides et solides au niveau du bassin versant de la rivière Jiu, à des divers échelles spatiales et temporelles. La rivière Jiu (339 km de longueur) est un des plus importants affluents du Danube en Roumanie.Dans le contexte actuel de la nécessité d’élaborer des plans de gestion du bassin avec un caractère intégré, englobant l’ensemble des facteurs naturels et anthropiques qui contrôlent l’écoulement solide et liquide, ainsi que les processus associés, le présent travail offre des informations sur la dynamique hydro-sédimentaire du bassin versant de la rivière Jiu, issues d’une recherche transdisciplinaire réalisée à différentes échelles spatiales et temporelles.Le bassin étudié se caractérise par des particularités géographiques complexes, déterminées par la diversité des facteurs naturels (géologiques, morphologiques, climatiques, édaphiques et de végétation) et socio-économiques. Du point de vue économique, l’élément qui donne l’individualité du bassin de la rivière Jiu est la présence et l’exploitation du charbon dans les secteurs supérieur (houille) et moyen (lignite). L’existence du charbon a été valorisée avec des différentes méthodes de laboratoire, concernant la teneur en charbon et éléments associés des sédiments collectés du lit de la Jiu et de ses principaux affluents.Ce travail se propose de répondre à deux questions majeures :(i) Quels sont les facteurs naturels et anthropiques contribuant à la production et au transfert des flux de matière liquide et solide au niveau du bassin de la rivière Jiu?(ii) Quelle est l’importance des échelles spatiales et temporelles dans l’analyse de la dynamique hydro-sédimentaire en relation avec les sources de sédiments, les événements hydrologiques extrêmes, les voies de transfert et les zones favorables à l’accumulation ?La démarche méthodologue a suivi une optique allant du général vers le particulier.Dans la première partie de la thèse, les analyses sont réalisées à l’échelle du bassin entier, afin de mettre en évidence les facteurs physiques et anthropiques contrôlant les flux liquides et solides. Les aspects traités portent sur la connectivité entre les sources, le transfert et les zones d’accumulation, ainsi que la relation entre le débit liquide et le débit solide et la cartographie des processus géomorphologiques génératrices de sédiments.Dans la deuxième partie de la thèse, on passe de la perspective systémique sur l’ensemble du bassin de la Jiu à une échelle beaucoup plus réduite, tant du point de vue spatial que temporel, afin d’identifier le rôle des crues dans la dynamique hydro-sédimentaire et la contribution des sous-bassins au transfert des sédiments fins. Du point de vue méthodologique, dans cette partie de la thèse, on passe des méthodes classiques de la géographie et de l’hydrologie, utilisées dans la première partie (basées sur la représentation cartographique et l’analyse spatiale dans le milieu SIG et sur l’analyse statistique des séries de données), vers une méthodologie complexe, intégrant l’analyse hydrologique (sur la base des indices de crue), la recherche sur le terrain (l’identification d’un site de dépôt d’alluvions et la collecte d’échantillons) et l’analyse des sédiments fins dans le laboratoire (par des techniques colorimétriques, géochimiques et de la pétrologie organique).Les résultats de la recherche ont mis en corrélation les facteurs de la dynamique hydro-sédimentaire à des diverses échelles spatiales et temporelles, dans une vision systémique. Les analyses de laboratoire des échantillons de sédiments et de charbon et les analyses des crues ont contribué à une meilleure connaissance de la dynamique hydro-sédimentaire, notamment les sources potentielles des sédiments, leur composition et leurs voies de transfert dans le bassin étudiéThe doctoral thesis titled “The Hydro-sedimentary dynamics of the Jiu River Watershed. A systemic and multi-scale approach” aimed to investigate the dynamics of liquid and solid flows at various temporal and spatial scales, in the Jiu River Basin. The study area is located in southwestern Romania, Jiu River (339 km long) being one of the most important Carpathian tributaries of the Danube river.In the current context, marked by the need to elaborate integrated watershed management plans, the present study offers valuable and original information on the hydro-sedimentary dynamics in the Jiu River watershed, that stems from a cross-disciplinary research carried out at different temporal and spatial scales.The watershed under study is characterized by complex geographical particularities, determined by a great diversity of natural and socio-economic factors. From an economic standpoint, the element that individualizes Jiu’s watershed is the presence and exploitation of coal in its upper sector (black coal) and middle sector (lignite), activities that have left their mark on the hydrological characteristics of the rivers in the basin. The presence of coal resources has been relied upon in this paper in order to investigate the hydro-sedimentary dynamics on the basis of an analysis, carried out through different laboratory methods, of the coal associated elements’ content in the alluvium samples collected in the riverbeds of Jiu and its main tributaries.The present research seeks to answer the following two major questions:(i) Which are the natural and human factors that contribute to the production and transfer of the solid and liquid fluxes within the Jiu River basin?(ii) What is the importance of spatial and temporal scales in the analysis of the hydro-sedimentary dynamics with regards to sediment sources, extreme hydrological events, transfer paths and the most favorable accumulation areas?The scientific methodology that we adopted followed a perspective that shifted from the general to the specific.In the first part of the thesis, the analysis was carried out at the scale of the whole basin, in order to highlight the physico-geographical factors, as well as the man-made ones, controlling the liquid and solid fluxes. The issues that we approached refer to the connectivity between sources – transfer – accumulation areas, hydrological variability and the relationship between the solid and the liquid discharge, the geomorphological mapping of alluvium-generating processes.In the second part of the thesis, we shifted from the systemic perspective of the whole Jiu River Basin towards a smaller scale, both spatially and temporally, able to reflect the role of the largest floods recorded in Jiu River Basin in the hydro-sedimentary dynamics and the contribution of its main sub-catchments in the sediment transfer. From a methodological point of view, in this part of the thesis we moved from the classical, geographical and hydrological methods, employed in the first part (based on mapping and GIS analysis, as well as by statistical processing of data series) towards a complex methodology, integrating hydrological analysis (on the basis of flood indices), field research and the complex analysis of fine sediments in the laboratory (through techniques belonging to colorimetric tracing, geochemistry, organic petrology).The results of our research connected the elements and factors behind the hydro-sedimentary dynamics at various spatial and temporal scales into a systemic vision. The laboratory analyses of the sediment and coal samples, the study of flood events and the hydrological and geomorphological analyses of Jiu watershed’s particularities have contributed to a better understanding of the hydro-sedimentary dynamics, offering original insight into potential sediment sources, the composition and quantity of sediments and the transfer paths they follow in the system of Jiu River’s watershed
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Coulon, Fanny. « Contribution à l’étude des sédiments marins lors d'opérations de dragage portuaire : re-sédimentation et mobilisation de la pollution organique ». Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20056/document.
Texte intégralRésumé :
Dans le cadre du dragage de Port-Camargue (projet national ECODREDGE-MED), l'objectif principal des travaux de thèse a été d'étudier la re-sédimentation des sédiments ré-immergés et d'appréhender les transferts de matière (particulaires et moléculaires) associés. Une approche expérimentale de caractérisation a été réalisée pour appréhender ces phénomènes, aux échelles macroscopiques (mécanismes de sédimentation), mésoscopiques (transferts de matière particulaires) et moléculaires (phénomènes de sorption). Les travaux ont porté sur l'étude de cinq sédiments et de leurs fractions granulométriques. Une méthode de séparation granulaire a donc été développée et optimisée en ce sens, soulignant l'importance de vérifier la qualité de la séparation lorsque les développements portent sur les fractions granulaires. L'approche morpho-granulaire utilisée dans la caractérisation de ces systèmes a permis, dans un premier temps, de mettre en évidence le comportement cohésif des sédiments et d'identifier différents types d'agglomérats. Elle a ensuite été utilisée pour proposer une méthode de classification simple et rapide des sédiments, basée essentiellement sur la détermination, par granulométrie laser, du rapport volumique limon/sable.En second lieu, le comportement à la re-sédimentation a été appréhendé en étudiant la stabilité physico-chimique des particules dans la colonne de sédimentation grâce à un analyseur de suspensions concentrées, le Turbiscan MA2000. Cette stratégie apporte de nouvelles connaissances, notamment sur les mécanismes de sédimentation et l'impact de certains paramètres comme le rapport limon/sable, la salinité ou la fraction volumique sur ces mécanismes. Combinée à l'analyse du Carbone Organique Total (COT), des transferts de matière ont été identifiés dans la colonne de sédimentation, via les phénomènes interparticulaires (agglomération/dispersion) et les phénomènes de sorption (adsorption/désorption)In the framework of Port-Camargue dredge (ECODREDGE-MED project), the main objective was to study the dredged sediment re-sedimentation and matter transfers (particular and molecular matter). An experimental characterization approach was realized in order to study these phenomena working at different scales : macroscopic (sedimentation mechanisms), mesoscopic (particular matter mobilization) and molecular (sorption phenomena). These research works focused on study of five sediments and their granular fractions. A dispersion granular method was developed and highlighted the importance to verify dispersion quality of processes concerning study of granular fractions. Morpho-granular approach used in theses works permitted to highlight cohesive aspect of sediments and to identify different agglomerate types. This approach was also used to propose a classification method of sediments, based on limon/sand ratio determination by laser granulometry.Secondly, re-sedimentation behavior was investigated studying physico-chemical stability of particles in the water column with a suspension analyszer (Turbiscan MA2000). The results contributed knowledge on sedimentation mechanisms and parameter (limon/sand ratio, salinity and volume fraction) influence. With the use of TOC analyze (Total Organic Carbone), matter transfers were identified in water column, via interparticular phenomena (agglomeration/dispersion) and sorption phenomena (adsorption/désorption)
Livres sur le sujet "Sediment transfert"
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S, Melis Theodore, United States. Bureau of Reclamation. et Geological Survey (U.S.), dir. Magnitude and frequency data for historic debris flows in Grand Canyon National Park and vicinity, Arizona. Tucson, Ariz : U.S. Dept. of the Interior, U.S. Geological Survey, 1995.
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Parker, W. R., et D. J. J. Kinsman, dir. Transfer Processes in Cohesive Sediment Systems. Boston, MA : Springer US, 1985. http://dx.doi.org/10.1007/978-1-4684-4763-7.
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M, Gurnell A., et Clark M. J, dir. Glacio-fluvial sediment transfer : An alpine perspective. Chichester [Sussex] : Wiley, 1987.
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Slatt, Roger M., et Carlos Zavala. Sediment transfer from shelf to deep water : Revisiting the delivery system. Tulsa, OK : Co-published by the American Association of Petroleum Geologists and SEPM, 2011.
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Mehta, Ashish J. Sediment transport and detrital transfer changes related to minimum flows and levels : Final report. Palatka, FL : St. Johns River Water Management District, 2004.
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A, Zarull Michael, International Joint Commission et Great Lakes Water Quality Board, dir. Proceedings of the technology transfer symposium for the remediation of contaminated sediments in the Great Lakes Basin : October 25-28, 1988, Canada Centre for Inland Waters, Burlington, Ontario / symposium chairman and proceedings editor, Michael A. Zarull. Windsor, Ont : International Joint Commission, Great Lakes Regional Office, 1990.
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A, Commeau Judith, et Geological Survey (U.S.), dir. Description and calibration results of an in situ suspended matter sampler : The McLane Water Transfer System. [Reston, Va.?] : U.S. Dept. of the Interior, U.S. Geological Survey, 1995.
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D, Sinigalliano Christopher, et United States. Environmental Protection Agency, dir. Detection of horizontal gene transfer by natural transformation in native and introduced species of bacteria in marine and synthetic sediments. [Washington, D.C : U.S. Environmental Protection Agency, 1992.
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Valentin, Golosov, Belyaev Vladimir, Walling D. E, Moskovskiĭ gosudarstvennyĭ universitet im. M.V. Lomonosova., International Association of Hydrological Sciences. et Symposium on Sediment Transfer Through the Fluvial System (2004 : Moscow, Russia), dir. Sediment transfer through the fluvial system : Proceedings of the International Symposium held at Moscow, Russia, from 2 to 6 August, 2004. Wallingford, UK : IAHS, 2004.
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Winfield, Kari A. Development of property-transfer models for estimating the hydraulic properties of deep sediments at the Idaho National Engineering and Environmental Laboratory, Idaho. Reston, Va : U.S. Geological Survey, 2005.
Trouver le texte intégralChapitres de livres sur le sujet "Sediment transfert"
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Hodgkins, Richard. « Sediment Transfer Modeling ». Dans Encyclopedia of Earth Sciences Series, 1010–14. Dordrecht : Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-90-481-2642-2_479.
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Garnier-Laplace, J., J. P. Baudin et L. Foulquier. « Experimental study of 110mAg transfer from sediment to biota in a simplified freshwater ecosystem ». Dans Sediment/Water Interactions, 393–406. Dordrecht : Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-2783-7_34.
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Tangi, Marco. « Dynamic Sediment Connectivity Modelling for Strategic River Basin Planning ». Dans Special Topics in Information Technology, 27–37. Cham : Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-15374-7_3.
Texte intégralRésumé :
AbstractSediment connectivity is a distributed property of river systems that emerges from the connected transfer of sediment between multiple sources and sinks. Its disruption, brought by anthropic disturbances, can have severe and unforeseen consequences on both fluvial ecosystems and human livelihood. Modeling network-scale sediment connectivity provides a foundational understanding of river processes and their response to new pressures and can be used to forecast future system evolutions. In this chapter, we present the basin-scale, dynamic sediment connectivity model D-CASCADE (Dynamic CAtchment Sediment Connectivity And DElivery), which quantifies spatiotemporal patterns of sediment delivery in river networks. D-CASCADE considers multiple factors affecting transport, including heterogeneities in hydrology and sediment supply, different grain sizes, channel morphological evolution, and reservoir presence and management. The model is designed to be flexible, data parsimonious, and computationally efficient. We also present two applications of D-CASCADE in real-world case studies for historic geomorphic evolution reconstruction and future dam impacts forecasting. D-CASCADE is intended for integrated, basin-scale water management efforts, to perform multiple screening of various decision portfolios for hydromorphological impact assessments.
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Lorenz, M. G. « Gene Transfer via Transformation in Soil/Sediment Environments ». Dans Gene Transfers and Environment, 95–101. Berlin, Heidelberg : Springer Berlin Heidelberg, 1992. http://dx.doi.org/10.1007/978-3-642-77450-8_11.
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Hanazaki, Hideshi. « The Energetics and the Heat and Mass Transfer in Unsteady Stratified Turbulence ». Dans Sedimentation and Sediment Transport, 51–54. Dordrecht : Springer Netherlands, 2003. http://dx.doi.org/10.1007/978-94-017-0347-5_6.
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Liu, Zhiqiang, et Linlin Wang. « Heat Transfer in Gas Hydrate Sediment ». Dans Lecture Notes in Civil Engineering, 553–58. Singapore : Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-2306-5_78.
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Church, Michael. « Fluvial Sediment Transfer in Cold Regions ». Dans Landscapes of Transition, 93–117. Dordrecht : Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-017-2037-3_5.
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Pilleboue, E., et J. M. Dorioz. « Mass-Balance and Transfer Mechanisms of Phosphorus in a Rural Watershed of Lac Leman, France ». Dans Sediments and Water Interactions, 91–102. New York, NY : Springer New York, 1986. http://dx.doi.org/10.1007/978-1-4612-4932-0_9.
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Warburton, Jeff. « Sediment Transfer in Steep Upland Catchments (Northern England, UK) : Landform and Sediment Source Coupling ». Dans Landform - Structure, Evolution, Process Control, 165–83. Berlin, Heidelberg : Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-75761-0_11.
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Brenner, Mark, et Michael W. Binford. « Material transfer from water to sediment in Florida lakes ». Dans Paleolimnology IV, 55–61. Dordrecht : Springer Netherlands, 1987. http://dx.doi.org/10.1007/978-94-009-4047-5_9.
Texte intégralActes de conférences sur le sujet "Sediment transfert"
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Ziarek, Zbigniew Jan. « DESIGNING GEOEDUCATIONAL TOOLS FOR GEOTOURISM NEEDS � A CASE STUDY OF THE OUTER FLYSCH CARPATHIANS ». Dans 24th SGEM International Multidisciplinary Scientific GeoConference 24, 45–52. STEF92 Technology, 2024. https://doi.org/10.5593/sgem2024/1.1/s01.06.
Texte intégralRésumé :
A geoeducational tools are innovative solutions used to popularize knowledge in the field of Earth Sciences and the promotion of geotourism. These methods enhance the appreciation of geodiversity, raising awareness about cognitive and aesthetic values. By adopting this approach, there is a commitment to geoheritage protection for future generations. The efficacy of geoeducational instruments relates on a knowledge of geological processes and their outcomes, coupled with adept geointerpretation. During the geointerpretative phase it is important to maintain correctness and reliable explanation of the most significant elements, while ensuring a comprehensible transfer of knowledge. The primary beneficiaries are geotourists and tourists interested in the genesis of inanimate natural objects. The purpose of the presented geoeducational tools is a simplified visualization of the key stages of the basin-tectonic history of the Carpathian Flysch Belt, starting from the processes of sediments deposition (Outer Carpathian flysch), to the formation processes of regional tectonic units (Outer Carpathian nappes) during the Alpine orogenesis. The designed tools are based on the concept of process geology, in which: (a) based on the factual description of the outcome (rock or geological structure), (b) the geological process is interpreted, and as a result, (c) a general model of environmental conditions consistent with the observations and interpretation is constructed � �from detail to general�. The presented models aim to visualize geological processes and exhibit their results in a clear and comprehensible way. In the process of modeling it is crucial to maintain a level of realism that allows for the creation of the most naturalistic depiction of the environment and the circumstances under which the analyzed process and its results could occur. The implementation of the projects allowed to determine the main attributes of the geoeducational tools: repeatability of the experiments, their clarity, expressiveness, spectacularity, and realism. Thanks to them, the recipient is able to learn and understand processes related to the deposition of clastic sediments that predominantly build the Flysch Carpathians and then formation of their nappes (accretionary prisms) as a result of orogenic fold-and-thrust movements. The finished products (films) may arouse the interest of museums and be applied to exhibitions.
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Ullmann, Amos, Neima Brauner, Guy Dahan, Tal Golan et Zvi Ludmer. « Phase Transition of Partially Miscible Solvents Induced by Heating Cycles : Application for the Remediation of Contaminated Sediments and Sludge ». Dans 2010 14th International Heat Transfer Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ihtc14-22856.
Texte intégralRésumé :
A novel process entitled “Sediments Remediation Phase Transition Extraction” (SR-PTE) is being developed for a simultaneous removal of both heavy metals and organic pollutants from contaminated sediments or sludge. The process uses partially miscible solvent mixtures, where one of the components is water. By heating the mixture above a certain temperature, a single phase is formed. This allows the organic solvent, containing an appropriate chelating agent, to penetrate the wetted sediment voids and efficiently extract simultaneously the organic and heavy metal pollutants. The phase separation, occurring during the cooling stage, is fast and allows the pollutants to propagate and concentrate in the lighter organic phase, leaving the sediments and the lower aqueous phase practically clean. The SR-PTE technology was tested on authentically polluted river sediments and on heavily contaminated sludge from a waste-water treatment plant. The extraction efficiency was found to improve by the phase transition cycle induced by temperature variation (about twice than that obtained when the extraction was carried out isothermally). Additionally, with the induced phase transition, the formation of stable emulsions is prevented albeit the presence of natural surfactants in the treated media. The process was tested on lab scale and bench-scale reactor. No significant effects of the process up-scaling from lab to bench scale were observed.
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« Thermal stability of CO2 hydrates in porous media with varying grain size in brine solution ». Dans Sustainable Processes and Clean Energy Transition. Materials Research Forum LLC, 2023. http://dx.doi.org/10.21741/9781644902516-13.
Texte intégralRésumé :
Abstract. In the present work, the heat transfer behavior of CO2 hydrate dissociation was studied in three quartz sand particles (QS-1, QS-2 and QS-3) with varying grain sizes. The heat transfer behavior was evaluated by determining the heating rates of the porous media (quartz sand) during the CO2 hydrate dissociation process in 3.3 wt.% NaCl. The experiment was performed using sandstone hydrate reactor by first forming the CO2 hydrates at 4 MPa and 274.15 K and then dissociating the hydrates from 274.15 to 277.15 K, respectively. The results indicate that the thermal response of the porous sediment was significantly influenced by the hydrates as well as the porous sediment properties. The heating rate of the porous media increased when the grain size increased. However, the presence of CO2 hydrates reduced the heat transfer behavior of the porous sediment due to the endothermic nature of hydrate dissociation. The heating behavior of the porous media with hydrates mainly depends on the type and pattern of hydrate formed (pore-filling, load-bearing, and cementation) and the location of the hydrates within the pores of the porous sediment. The pore-filling type of hydrate formation in porous sediments provides high thermal stability for CO2 hydrate storage due to its less contact with the quartz sand particles. However, the pore-filling hydrate formation type is challenged with low or undesired CO2 hydrate storage capacity. These findings will provide meaningful insights to select favorable sediment properties/sites for CO2 storage in the hydrate form in porous sediments.
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Yu, Xichong, Li Gang, Weixin Pang et Wu Yaling. « Heat and Mass Transfer Mechanism of Gas Hydrate Development for South China Sea ». Dans ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/omae2014-23202.
Texte intégralRésumé :
The decomposition process of gas hydrate in sediments is actually the dynamic phase transition process of solid hydrate in sediments after absorbing heat decomposition. According to the phase equilibrium characteristics of gas hydrate, there are three basic development methods, including heating, chemical injecting and depressurization. Currently, there is no good commercial software used to simulate heat transmission and mass transfer in the gas hydrate decomposition process. So in this paper, based on typical gas hydrate sediment in South China Sea, microcosmic, mesocosmic (fractal theory) and macrocosmic scales are respectively used to successfully reveal the heat and mass transfer mechanism of three basis development methods. Molecular dynamics simulation shows heat injection is the best method for heat and mass transferring, and chemical injecting is better than depressurization. Fractal theory is successfully used to describe the complex structure of the porous sediments with gas hydrate occurrence, and can realize the prediction of heat and mass transfer law of hydrate dissociation in porous media. Macrocosmic numerical simulation of depressurization for gas hydrate sediment in South China Sea shows gas hydrate reservoir geological model has a large influence on the gas hydrate decomposition, and permeability and hydrate saturation of the upper cover layer have great effect on gas hydrate decomposition. It is poor development efficiency for only depressurization development and the problem of water drainage should be paid attention during development process.
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Al-Ghamdi, Abdullah Saeed. « Effect of Fine Sediments on the Performance of Axial Pumps ». Dans ASME 2008 Fluids Engineering Division Summer Meeting collocated with the Heat Transfer, Energy Sustainability, and 3rd Energy Nanotechnology Conferences. ASMEDC, 2008. http://dx.doi.org/10.1115/fedsm2008-55003.
Texte intégralRésumé :
This study presents experimental work done to investigate the effect of fine sediment concentration on the performance of axial pumps. The pump was tested at three different motor speeds of 1000 rpm, 1150 rpm and 1350 rpm. At each motor speed, the pump was tested at three different sediment concentrations by weight of 0%, 2.485% and 8.10%. The sediment used in the investigation consists of a mixture of fine sand, silt and clay (16% fine sand, 38% silt and 46% clay). Results show that the efficiency of the axial pump is negatively influenced by the presence of fine sediments in the flow. As the sediment concentration increases to 8.10% the maximum reduction in axial pump’s efficiency for the range tested reached about 30% for motor speed of 1350 rpm and up to 40% for the lower motor speed of 1000 rpm. The reduction in the efficiency may be attributed to the change in the viscosity of the fluid that required higher torque (hence higher input power) to produce the same discharge. These results provide an evidence of a considerable reduction of axial pumps efficiency when used to pump water with fine sediment of silt and clay. However, further investigation is recommended for commercial size pumps and at different sediment concentrations and different composition of sediment.
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Radulescu, Victorita. « Estimation of the Risk Zones Affected by Repeated Floods by Numerical Modeling ». Dans ASME 2020 Fluids Engineering Division Summer Meeting collocated with the ASME 2020 Heat Transfer Summer Conference and the ASME 2020 18th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/fedsm2020-20443.
Texte intégralRésumé :
Abstract In Romania, in the last decades, was not realized any complex plan of management concerning the environmental rehabilitation of the natural riverbeds, even if there are even in present many places confronted with repeated floods. After the floods from 2004, 2005 and 2014 have been recorded in some places large deposits of sediments or contrary, in other zones with erosion and uncontrolled coastal slides. As an immediate effect, zones with risk for the local population and not only, have appeared. The present paper estimates the capacity of transport for a riverbed in natural conditions, based on the local measurements registered before and after a flood. The model is tested for a tributary of the Bistrita River, the Cracau River, near the Siret basin, an area well-known for such repeated floods sometimes even two or three recorded in the same year, as it was in 2005 and 2008. Three of these floods were confronted with human losses, many dead animals, and agricultural flooded areas. Near the analyzed watercourse there are many localities, with a high density of population. The realized numerical model for the flow with free surface was taking into account the possibility of the permanent changing of the lateral surfaces (riverbeds) during the floods. A continuous balance of the entered and transported sediments is realized, due to the erosion and sediment transportation. The time variation of the discharged liquid and the solid phases are directly connected with the sediment transport. In these conditions, the fine fractions of sediments from the bed’s structure are removed from its surface. In some places, the sediments become “armored” with the coarser part of the bed sediment. It is proposed a mathematical model to simulate the effect of both types of deposits into a fluid flow in open channels, with a movable bed. The entire alluvial stream, until the base rock, is considered with a small thickness so the non-uniformity of the grain size in the vertical distribution in riverbed could be neglected. The boundary conditions in the flood analysis consist of the upstream hydrograph and the stationary level of the downstream watercourse. Knowing the flow rate and the water levels by direct measurements, there is possible to establish the risk zones, far away from the river borders. The primary purpose of this study is to minimize the effects of such uncontrolled floods by determining the risk zones and to present a solution for increasing population safety which lives near the riverbed. Finally, some conclusions and references are mentioned.
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Zhao, Ermeng, Jian Hou, Yunkai Ji, Lu Liu, Yongge Liu et Yajie Bai. « The Key Factors of Low-Frequency Electric Heating Assisted Depressurization Method in the Exploiting of Methane Hydrate Sediments ». Dans SPE Europec featured at 82nd EAGE Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/205119-ms.
Texte intégralRésumé :
Abstract Natural gas hydrate is widely distributed in the permafrost and marine deposits, and is regarded as an energy resource with great potential. The low-frequency electric heating assisted depressurization (LF-EHAD) has been proven to be an efficient method for exploiting hydrate sediments, which involves complex multi-physics processes, i.e. current conduction, multiphase flow, chemical reaction and heat transfer. The physical properties vary greatly in different hydrate sediments, which may profoundly affect the hydrate decomposition in the LF-EHAD process. In order to evaluate the influence of hydrate-bearing sediment properties on the gas production behavior and energy utilization efficiency of the LF-EHAD method, a geological model was first established based on the data of hydrate sediments in the Shenhu Area. Then, the influence of permeability, porosity, thermal conductivity, specific heat capacity, hydrate saturation and hydrate-bearing layer (HBL) thickness on gas production behavior is comprehensively analyzed by numerical simulation method. Finally, the energy efficiency ratio under different sediment properties is compared. Results indicate that higher gas production is obtained in the high-permeability hydrate sediments during depressurization. However, after the electric heating is implemented, the gas production first increases and then tends to be insensitive as the permeability decreases. With the increasing of porosity, the gas production during depressurization decreases due to the low effective permeability; while in the electric heating stage, this effect is reversed. High thermal conductivity is beneficial to enhance the heat conduction, thus promoting the hydrate decomposition. During depressurization, the gas production is enhanced with the increase of specific heat capacity. However, more heat is consumed to increase the reservoir temperature during electric heating, thereby reducing the gas production. High hydrate saturation is not conducive to depressurization because of the low effective permeability. After electric heating, the gas production increases significantly. High HBL thickness results in a higher gas production during depressurization, while in the electric heating stage, the gas production first increases and then remains unchanged with the increase of thickness, due to the limited heat supply. The comparison results of energy efficiency suggest that electric heating is more advantageous for hydrate sediments with low permeability, high porosity, high thermal conductivity, low specific heat capacity, high hydrate saturation and high HBL thickness. The findings in this work can provide a useful reference for evaluating the application of the LF-EHAD method in gas hydrate sediments.
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Liang, Bingchen, Ying Liu et Lili Yang. « Numerical Experiments Analysis of Wave-Induced Vertical Mixing’s Effects on Sea Surface Wind-Induced Momentum Transfer ». Dans ASME 2010 29th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/omae2010-20739.
Texte intégralRésumé :
A hydrodynamic sediment coupled model COHERENS-SED, which has been developed by the present authors through introducing wave-enhanced bottom stress, wave dependent surface drag coefficient, wave-induced surface mixing, SWAN, damping function of sediment on turbulence and sediment model to COHERENS, is modified to account for wave-induced vertical mixing. One equation k–ε turbulence model is taken into account in calculating vertical viscosity coefficient. COHERENS-SED consists of sediment model SED, current model COHERENS and wave generation model SWAN. The model can also calculate one-dimensional, two-dimensional and three-dimensional current separately. One-dimensional model and three-dimensional model are adoptted to study the wave-induced vertical mixing’s effects. The horizontal current velocity profiles given by the model, with same input conditions as what to get analytical results, are in nice agreement with analytical velocity profiles. Therefore the model can be reliable to identify wave-induced vertical mixing’s effects on horizontal velocity profiles and momentum transferring. Two group numerical experiments are built based on 130m water depth and 20m water depth for the one-dimensional model. Results show that higher wave height can generate larger vertical eddy viscosity and lower horizontal velocity generally. In order to find out such effects on fresh water flume momentum transfer towards down in vertical section of estuary, Yellow River delta is chosen to study the effects of wave-induced vertical diffusion on sediment vertical mixing and the Yellow River estuary vertical cross-section is chosen to study fresh water disperse range in vertical section. The results of fresh water shows that wave-induced vertical mixing increases the momentum of fresh water transferring ability towards down to seabed. So fresh water flume length is compressed obviously.
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Maroni, C. S. « Picking of sediment layers using multiresolution analysis ». Dans Seventh International Conference on Electronic Engineering in Oceanography - Technology Transfer from Research to Industry. IEE, 1997. http://dx.doi.org/10.1049/cp:19970668.
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Doolittle, Daniel, Eric Swanson, Craig Scherschel, Eugene Revelas, Kathryn Rovang et Stephen Varnell. « Integrated and Adaptable Approach to Mapping Benthic Habitats to Support Offshore Wind Development off the Mid-Atlantic Outer Continental Shelf ». Dans Offshore Technology Conference. OTC, 2023. http://dx.doi.org/10.4043/32390-ms.
Texte intégralRésumé :
Abstract Offshore wind developers obtain extensive geophysical, geotechnical, and habitat data during Site Characterization activities. Integration and delivery of this information to a diverse group of stakeholders and Government agencies is required. We present an integrated benthic habitat mapping approach tailored to regional geology and ground conditions and discuss how various data was utilized to deliver multiple components of the permitting process. Multiple data sets were integrated and presented via a web-based GIS platform to aid delivery, visualization, and communication. Our unified approach to benthic habitat mapping and delivery of products to stakeholders was instrumental in successfully coalescing multiple performers to develop their individual deliverables in a cohesive and rapid manner. This approach reduced risk to schedule and budget, without sacrificing data density or quality. Four annual (2019–2022) benthic surveys were acquired to support Site Characterization and subsequent permitting processes. High-Resolution Geophysical data were collected concomitantly with the 2020 benthic survey data and used to refine subsequent 2021 and 2022 benthic survey designs. Benthic survey data consisted of grab sample tests (grain size), macrofaunal taxonomy, sediment profile and plan view imagery (SPI-PV), video imagery from each grab station, and towed video transects. Acoustic data products were processed and interpreted to create polygons of seafloor sediment coverage over the ASOW study area and ground-truthed with physical sampling, video, and digital still imagery to refine and validate acoustic data into a mappable model of essential fish and benthic habitats. Seafloor morphology and seabed sediment interpretations were coalesced into a benthic habitat model that displayed substrates consisting mostly of mobile sand sheets, with interspersed areas of gravelly sand and discrete patches of gravel. Overlying the substrate model was a range of benthic features and morphologies, including sand ridges, sand waves, megaripples, ripples, areas of depressional marks, hummocky seafloor, interbedded surficial sediments, irregular seafloor, and localized relief features. From these data, classified maps of Coastal Marine Ecological Standard (CMECS) substrates and fish habitats were made. Additional CMECS classification of benthic biotic components were mapped, showing the taxonomic communities that are present in each substrate. Seabed sediment modeling and morphological trends were dynamically studied and compiled into an interpreted and GIS-friendly dataset that enabled rapid online transfer to subject matter experts tasked with quantifying the benthic ecosystem across the development area. The methods and modeling that were produced by expert refinement of geophysical data to reflect the physically observed habitat structures allowed for dynamic minimum mapping unit variability while also isolating and identifying key areas of interest for benthic researchers and regulators. This mapping process led to an efficient and unified approach for all teams, saving project time and expense.
Rapports d'organisations sur le sujet "Sediment transfert"
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Ding, Yan, Sung-Chan Kim, Rusty L. Permenter, Richard B. Styles et Jeffery A. Gebert. Simulations of Shoreline Changes along the Delaware Coast. Engineer Research and Development Center (U.S.), janvier 2021. http://dx.doi.org/10.21079/11681/39559.
Texte intégralRésumé :
This technical report presents two applications of the GenCade model to simulate long-term shoreline evolution along the Delaware Coast driven by waves, inlet sediment transport, and longshore sediment transport. The simulations also include coastal protection practices such as periodic beach fills, post-storm nourishment, and sand bypassing. Two site-specific GenCade models were developed: one is for the coasts adjacent to the Indian River Inlet (IRI) and another is for Fenwick Island. In the first model, the sediment exchanges among the shoals and bars of the inlet were simulated by the Inlet Reservoir Model (IRM) in the GenCade. An inlet sediment transfer factor (γ) was derived from the IRM to quantify the capability of inlet sediment bypassing, measured by a rate of longshore sediments transferred across an inlet from the updrift side to the downdrift side. The second model for the Fenwick Island coast was validated by simulating an 11-y ear-long shoreline evolution driven by longshore sediment transport and periodic beach fills. Validation of the two models was achieved through evaluating statistical errors of simulations. The effects of the sand bypassing operation across the IRI and the beach fills in Fenwick Island were examined by comparing simulation results with and without those protection practices. Results of the study will benefit planning and management of coastal sediments at the sites.
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Wilkins, Justin, Andrew McQueen, Joshua LeMonte et Burton Suedel. Initial survey of microplastics in bottom sediments from United States waterways. Engineer Research and Development Center (U.S.), septembre 2021. http://dx.doi.org/10.21079/11681/42021.
Texte intégralRésumé :
Given the reported extent of microplastics in the aquatic environment, environmentally relevant exposure information for sediments dredged by the US Army Corps of Engineers will lend context to the risks posed by this contaminant during dredging. We measured the occurrence, abundance, and polymer composition of microplastics in sediments collected from nine dredged waterways and two non-dredged reference areas. The number of particles in sediment samples ranged from 162 to 6110 particles/kg dry wt., with a mean of 1636 particles/kg dry wt. Fragments were the most prevalent shape observed among the 11 study sites (100% frequency of occurrence), followed by fibers (81%), spheres (75%), foams (38%) and films (34%). Based on analyses of chemical composition of the particles using Fourier transform infrared spectroscopy, polyethylene:propylene was the most common polymer type observed. Consistent with results presented by other investigators microplastic concentrations and polymer types in bottom sediments in this study were also aligned with the most widely used plastics worldwide.
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Hart, Kate, Jodi Lejeune, Rebecca Beavers, Sam Whitin, Christopher Overcash, Monique LaFrance Bartley et Suzie Boltz. National Park Service beach nourishment guidance (second edition). National Park Service, mai 2023. http://dx.doi.org/10.36967/2299256.
Texte intégralRésumé :
Sandy coastal areas (including coastal dunes, beaches, and submerged intertidal and nearshore areas) are naturally dynamic ecosystems. These areas experience accretion, erosion, dune and island migration, overwash, and other processes as sediments are transported by the wind, waves, tides, and currents. If these natural physical processes are disrupted, the beach ecosystem may transform, become unstable, or disappear completely over time. Human development of coastal areas, sea level rise, and increasing frequency and intensity of coastal storms are examples of coastal change that interfere with sediment transport and therefore threaten the stability of coastal ecosystems. Beach nourishment is a nature-based engineering strategy that artificially delivers sand (a size of sediment) to a coastal ecosystem to lessen the disruption of sediment supply. Generally, beach nourishment is intended to mitigate erosion, protect infrastructure and buildings, and/or to restore habitat. The National Park Service (NPS) has produced an updated guidance manual that provides a consistent approach to beach nourishment based on sound coastal science and engineering. The goal of this updated guidance is to provide information on this method to protect and preserve the beaches and associated resources of the National Park System.
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Sobecky, Patricia A. Plasmid Diversity and Horizontal Transfer in Marine Sediment Microbial Communities. Fort Belvoir, VA : Defense Technical Information Center, février 2002. http://dx.doi.org/10.21236/ada399348.
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Zurk, Lisa M. A Radiative Transfer Model for Acoustic Propagation in Ocean Sediment Layers. Fort Belvoir, VA : Defense Technical Information Center, septembre 2009. http://dx.doi.org/10.21236/ada531885.
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Zurk, Lisa M. A Radiative Transfer Model for Acoustic Propagation in Ocean Sediment Layers. Fort Belvoir, VA : Defense Technical Information Center, septembre 2012. http://dx.doi.org/10.21236/ada575146.
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Bentley, Sr, et Samuel J. Quantitative Chemical Mass Transfer in Coastal Sediments During Early Diagenesis. Fort Belvoir, VA : Defense Technical Information Center, août 2001. http://dx.doi.org/10.21236/ada626797.
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Furukawa, Yoko. Quantitative Chemical Mass Transfer in Coastal Sediments During Early Diagenesis. Fort Belvoir, VA : Defense Technical Information Center, septembre 2001. http://dx.doi.org/10.21236/ada626870.
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Vaughan, Chad, et Dawn Lavoie. Quantitative Chemical Mass Transfer in Coastal Sediments During Early Diagenesis. Fort Belvoir, VA : Defense Technical Information Center, septembre 2001. http://dx.doi.org/10.21236/ada626900.
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Zhao, Bei, James Laszlo et Heather Kaminsky. PR-461-14602-R02 Sample Mixing and Centrifugal Forces on Density and Sediment-Water Results. Chantilly, Virginia : Pipeline Research Council International, Inc. (PRCI), juin 2018. http://dx.doi.org/10.55274/r0011492.
Texte intégralRésumé :
The crude oil being transported by pipeline varies widely in density, viscosity, sulfur content, and other fluid properties. In a custody transfer, both parties are concerned with the quantity and the quality of the crude oil since this determines the monetary value of the transaction. The objective of this project is to investigate various factors that can impact accurate determination of the density, sediment and water content of crude. The findings will be critical to improve current procedures, including proper sample mixing and handling, analytical methodologies, and operation parameters, so that reliable and accurate custody transfer can be provided to all involved parties internationally. This project investigated the impact of mixing and analytical methodologies on crude density and S and W determination. Operating parameters tested included mixing time (3 or 5 minutes), mixing system (new or old) and sample size (3 or 7 liters). Density determination was conducted by a thermos-hydrometer test and a digital density meter and the results were compared. S and W content was quantified by the centrifuge method and Karl Fischer titration and the results were compared. For the centrifuge method, the impact of two centrifugal forces on S and W results was also studied. There is a related webinar.