Dissertations / Theses: '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.

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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 Durance
In 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.

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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 bioamplification
The 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.

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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 uniques
Significant 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.

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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 risque
Erosion 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.

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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 remédiation
Soil 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.

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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 remédiation
Soil 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.

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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 rivière
The 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.

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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 urbain
The 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.

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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 étudié
The 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.

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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)

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Viennet, David. "Utilisation de la morphogranulométrie dans le suivi source to sink du transfert particulaire dans les bassins versants." Thesis, Normandie, 2020. http://www.theses.fr/2020NORMR016.

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De nos jours, la compréhension des transferts de particules sédimentaires (Source to Sink) est un enjeu clef des géosciences. Un des challenges dans ce domaine est la caractérisation de l’origine et des processus de transfert des particules. L’utilisation de la morphométrie (la mesure de la forme d’une particule) est une méthodologie pouvant apporter des réponses à ces questions.La morphométrie des particules est utilisée en sédimentologie pour identifier les différents stocks sédimentaires, les transferts et les mécanismes de sédimentation. Actuellement, beaucoup d’analyses morphométriques sont généralement réalisées avec un Microscope Électronique à Balayage (MEB) couplé à une analyse d’image. Cette dernière consiste en un programme informatique qui distingue les particules de leur arrière-plan et calcule leur forme suivant différents paramètres tel que l’élongation, la circularité ou la convexité. Cette méthode complexe demande beaucoup de temps. Une nouvelle méthodologie est présentée dans cette thèse utilisant l’approche morphométrique grâce à un appareil de mesure en continue à flux dynamique (caméra couplée à une pompe péristaltique). Ce dernier consiste à prendre des images alors qu’un échantillon d’eau circule à travers une fenêtre d’écoulement, permettant à l’utilisateur d’analyser de grandes quantités de particules en un temps réduit. Des analyses statistiques sont réalisées sur les paramètres de forme, calculés au préalable par analyse d’image, afin de discriminer les différents stocks de particules. La problématique de ces travaux de thèse est de savoir si la morphométrie peut constituer un proxy du transfert particulaire dans les bassins versants. Pour cela, une approche en 4 étapes a été entreprise afin de (1) vérifier si les données de taille et de forme peuvent discriminer des échantillons de sédiments ; (2) utiliser ces résultats pour évaluer la contribution de sources sédimentaires dans des mélanges expérimentaux contrôlés ; (3) établir un protocole de mesure et de traitement automatisé des données sédimentaires ; et (4) appliquer cela à plusieurs hydrosystèmes. La première étude est réalisée sur le bassin versant du fleuve Thio, sur lequel une activité minière est présente. Des mesures de taille et de forme ont été effectuées sur des sédiments de laisses de crue afin d’estimer la part de cette activité minière dans les stocks sédimentaires du fleuve et de ses affluents. Un modèle de contribution des sources (les affluents) dans les mélanges (le fleuve) a été établi et montre des résultats cohérents. Ces résultats apportent des informations sur les transferts sédimentaires entre les affluents et le fleuve Thio qui seront comparées à d’autres études utilisant des méthodes de traçage sédimentaires différentes. La seconde étude se concentre sur le bassin versant karstique de la source du Hannetot. Des carottes sédimentaires ainsi que les matières en suspension ont été étudiés sur différents points du bassin versant. Les différents tests réalisés montrent des variations dans les contributions des sources sédimentaires dans le temps. Différents proxies saisonniers et météorologiques contrôlant ces variations ont été identifiés. La dernière étude est un cas appliqué au forage d’alimentation en eau potable de la ville de Gisors pompant dans un aquifère karstique. Son but est d’identifier l’origine des sédiments provoquant des pics de turbidité lors de fortes précipitations. Le modèle de contribution des sources isole plusieurs sources potentielles et montre une augmentation dans les contributions de certaines lors des pics de turbidité. Toutes ces études montrent l’intérêt de la morphogranulométrie en tant que traceur sédimentaire. Elles démontrent également que cette technique est d’autant plus intéressante lorsqu’elle est en combinaison avec d’autres méthodes de traçage sédimentaire
Source to sink is one of the main concepts in Earth Sciences for a better knowledge of hydrosystems dynamics. Regarding this issue, one challenge consists in the characterization by in-situ measurements of the sources of suspended sediment, or sediment source fingerprinting. Few methods can fully cover such requirements and among them, the methodology using the grain shape deserves to be developed. Indeed, morphometry of particles is widely used in sedimentology to identify different sedimentary stocks, source-to-sink transport and sedimentation mechanisms. Currently, most grain shape analyses are carried out with a scanning electron microscope coupled to image analysis to measure various size and shape descriptors on particles like elongation, circularity, bluntness or fractal dimension. However, complexity and time of analysis are the main limitations of this technique for a long-term monitoring of SPM transfers. Here we present an experimental morphometric approach using a morphogranulometer (a CCD camera coupled to a peristaltic pump). The camera takes pictures while the sample is circulating through a flow cell, leading to the analysis of numerous particles in a short time. The image analysis provides size and shape information discriminating various particles stocks by statistical analyses. The aim of this thesis is (1) to calibrate the device and understand how the size and shape data can discriminate pure sediment samples; (2) use those results to evaluate the contribution of contrasted sedimentary sources in a mix; (3) to establish a measurement and data analysis protocol; and (4) use those protocol and methodology for several case studies of sediment transfers in various hydrosystems. The first case study presented concern the watershed of the Thio river, on which there is mining activity. A sediment fingerprinting study using size and shape characterization was carried on. The sediment sources of the different tributaries of the Thio river were analyzed as sources and the sediments of the main river itself were used as mixes of these sources. A model of the contributions of the sources in the mixes was achieved and its results show great coherence. It brings information on the transfers of the sediments between the different tributaries and the Thio river which will be later combined to other studies using different fingerprinting methods to evaluate the impact of the mining activity in these transfers. The second study focus on the karstic watershed of the Hannetot spring. Measurements were carried out on various field samples, from suspended sediments to core samples. Several experiments allowed to identify the varying contributions of different sediment sources through time. Several proxies were identified, seasonal and meteorological, as controlling factor for these variations. The last study is also a fingerprinting study of a karstic system. Its aim is to evaluate the origin of sediment sampled during turbidity peaks in the drinking water well of the town of Gisors. The source contribution model identified several potential sources of sediments and shows the increased contributions of certain sources during the flood period. All those studies shows that size and shape measured with the morphogranulometer are a good tracer for fingerprinting studies. They also demonstrate that this technique performs better in combination to other methods and brings the need to carry more studies combining morphogranulometry with several other fingerprinting techniques

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Warburton, J. "Alpine proglacial fluvial sediment transfer." Thesis, University of Southampton, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234150.

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Layglon, Nicolas. "Comportement des éléments traces métalliques lors de la remise en suspension de sédiments contaminés en zone côtière." Electronic Thesis or Diss., Toulon, 2020. http://www.theses.fr/2020TOUL0009.

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Les éléments traces métalliques arrivant dans le milieu marin s’accumulent naturellement dans les sédiments. En zone portuaire, ces sédiments peuvent être remis en suspension dans la colonne d’eau par des phénomènes naturels (houles, tempêtes…) et/ou anthropiques (trafic maritime, activité de dragage). En particulier, la Méditerranée Nord-occidentale représente un lieu d’échanges maritimes conséquents, engendrant des évènements de remise en suspension d’origine anthropique fréquents, tout en étant peu soumise à l’influence des phénomènes naturels liés aux marées. Dans ce contexte, les objectifs de cette thèse consistaient à étudier le potentiel de remobilisation des éléments traces lors d’évènements de remise en suspension afin d’apporter des connaissances contribuant à mieux prédire et ainsi mieux gérer le risque associé. Les cinétiques de transferts des ETMMs, étudiés lors d’expérimentations en laboratoire, ont été précisées à la lumière de la variabilité des contextes portuaires. Le transfert des ETMMs durant les 5 premiers jours de remise en suspension est apparu déterminé principalement par des processus abiotiques. La compréhension de ces processus a permis d’expliquer partiellement les observations de terrain réalisées lors d’une étude d’impact d’une opération de dragage
Trace metal elements entering marine environment accumulate in the sediments. In harbor areas, sediment can be resuspended in the water column following natural (swells, storms ...) and/or anthropic events (maritime traffic, dredging activity). In particular, the Mediterranean Sea represents a significant maritime trade route, generating frequent resuspension events of anthropic origin, while being slightly subjected to the influence of natural tidal phenomena. In this context, the objectives of this thesis consisted in evaluating the potential of trace elements during re-suspension events in order to provide knowledge that would help to better predict and thus better manage the associated risk. The kinetics of trace metal elements, studied in laboratory experiments, were specified in light of the variability of harbor contexts. During the first 5 days of suspension, trace elements transfers appeared mainly determined by abiotic processes. The understanding of these processes partially explained the field observations performed during an impact study of a dredging operation

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Grayson, Richard Philip. "Excess Â²Â²â¶Ra chronology of lake and deep-sea sediments : an investigation of controls over sediment-water transfer." Thesis, University of Liverpool, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426105.

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Didoné, Elizeu Jonas. "Erosão bruta e produção de sedimentos em bacia hidrográfica sob plantio direto no planalto do Rio Grande do Sul." Universidade Federal de Santa Maria, 2013. http://repositorio.ufsm.br/handle/1/5573.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The impact of agriculture on water resources has been a focus for problems associated with reservoir siltation, depletion of water quality, reduced infiltration and soil water storage, formation of floods and low water availability during drought periods. In this sense the estimation of gross erosion and sediment yield monitoring reflect the dynamic that occurs in catchments and the processes observed in the rivers. Studies of erosion in grain crop agricultural areas using no-tillage systems are scarce at catchment scale. Thus, this study estimated gross erosion and sediment yield in a large catchment representative of grain crop cultivation and its potential impacts on land degradation and consequent impacts on water resources. The catchment is located on the Riograndense plateau characterized by deep and weathered soils and landscape is gently sloping. Gross erosion estimation was performed with the RUSLE model along with a Geographic Information System where the attributes of soil, climate, landscape, and land use and management were spatialized for the entire drainage area of the catchment (800 km2). The catchment is drained by the Conceição River, which includes towns such as Cruz Alta and Ijuí, among others. The hydrossedimentometric monitoring was carried out for twenty months with automatic instruments, daily sample collection and sampling during rainfall-runoff events. The variables monitored were rainfall, flow, turbidity and suspended sediment concentration. From this data set sediment yield was estimated for the period and a sediment discharge rating curve was established to extrapolate sediment yield for the last decade. The average results of gross erosion for the catchment are in the order of 8 t ha-1 year-1 and average sediment yield was 140 mg km-2 year-1, generating sediment delivery ratio values of 17.5 %. From the temporal and spatial variability of the results, this study seeks to highlight the erosion processes operating at this scale and the implications for management and water and soil conservation programs for similar regions.
O impacto da agricultura nos recursos hídricos tem sido enfoque para problemas associados ao assoreamento de reservatórios, depauperamento da qualidade da água, reduzida infiltração e armazenamento de água no solo, formação de enxurradas e baixa disponibilidade hídrica em períodos de estiagem. Neste sentido a estimativa da erosão bruta e o monitoramento da produção de sedimentos refletem a dinâmica que ocorre nas bacias vertentes e os processos observados nos rios. Estudos de processos erosivos em áreas agrícolas sob produção de grãos em sistema plantio direto são incipientes na escala de bacia hidrográfica. Este estudo estimou a erosão bruta e a produção de sedimentos em uma grande bacia agrícola que representa o processo de produção de grãos e o seu potencial reflexo sobre a degradação dos solos e o impacto nos recursos hídricos. A bacia se localiza no planalto Riograndense caracterizada por solos profundos e intemperizados e relevo suave ondulado. A estimativa da erosão bruta foi realizada com o modelo RUSLE acoplado a um Sistema de Informação Geográfica, onde os atributos de solo, clima, relevo, uso e manejo foram espacializados para toda a área de drenagem da bacia (800 km2). A bacia em questão é drenada pelo rio Conceição que engloba os municípios de Cruz Alta e Boa Vista do Cadeado, dentre outros. O monitoramento hidrossedimentométrico foi realizado durante vinte meses com instrumentos automáticos, coletas de amostras diárias e amostras durante eventos de chuva-vazão. As variáveis monitoradas foram precipitação, vazão, turbidez e concentração de sedimentos em suspensão. A partir desse conjunto de dados foi estimada a produção de sedimentos no período, bem como estabelecida uma curva-chave de sedimentos utilizada para a extrapolação da PS para a última década. Os resultados médios da erosão bruta da bacia estão na ordem de 8 t ha-1 ano-1 e a produção de sedimentos média foi de 140 t km-2 ano-1, gerando valores de razão de entrega de sedimentos de 17,5%. A partir da variabilidade temporal e espacial dos resultados, o trabalho procura salientar os processos erosivos operantes nessa escala e as implicações para os programas de manejo e conservação de água e solo para regiões semelhantes.

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Blaes, Estelle. "Détermination des constantes de temps des processus d'altération et de transfert sédimentaire par les nucléides des séries de l'U : étude d'un bassin versant de Porto Rico et du système himalayen." Thesis, Strasbourg, 2013. http://www.theses.fr/2013STRAH007.

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Cette thèse se propose de définir les temps caractéristiques des processus d’altération à l'échelle de profil d'altération (bassin versant de Rio Icacos à Porto Rico) et de transfert sédimentaire subséquent dans les plaines alluviales (bassins du Gange et du Brahmapoutre). Cette problématique est abordée par l’analyse des nucléides des séries de désintégration radioactives de l’uranium-238. L’étude du système d’altération sphéroïdale développée sur le site de Porto Rico a permis de développer une méthode numérique de type quasi-Newton afin de résoudre le système d'équations qui rend compte du comportement des nucléides et du taux de formation de la saprolite et des couronnes d’altération.Pour les bassins du Gange et du Brahmapoutre, les sédiments ont été collectés sur différents affluents et à son exutoire. La variation des déséquilibres 238U-234U-230Th dans les sédiments, différente pour les sédiments en suspension et les sédiments à grains grossiers d’amont en aval, semble être une caractéristique générale des rivières himalayennes coulant dans la plaine Indo-gangétique. Par ce travail de thèse, nous avons montré l’utilité d’inclure l’analyse du 226Ra à l’analyse des autres nucléides de la chaîne de décroissance radioactive de l’238U (l’238U -234U-230Th 230Th) pour déterminer un taux d’altération dans un système bien défini. Néanmoins, l’étude du système du Brahmapoutre montre que la méthode proposée demande à être affinée car le transfert sédimentaire est un processus plus complexe dû à la variabilité minéralogique, granulométrique et à la dynamique sédimentaire (locale) des échantillons récoltés
This thesis proposes to define the time-scales of weathering processes on a spheroidal weathering profile, (Rio Icacos watershed, Puerto Rico ) and the transfer time of sediments within alluvial plains (Ganges and Brahmaputra basins). This issue is addressed through the analysis of the nuclides of the 238U decay chain. The study of a spheroidal weathering system developed on the site of Puerto Rico permit to develop a limited memory quasi-Newton algorithm in order to solve the system of equations that reflects the behavior of nuclides and the rate of formation of the saprolite and the rindlet zone. For the Ganges and Brahmaputra basins, sediments were collected from different tributaries and their outlets. The variation of 238U - 234U - 230Th disequilibria in the sediments, with different variation trends for suspended and coarse-grained sediments, is probably a general feature of all Himalayan rivers flowing across the Indo-Gangetic plain. For this work, we have shown the usefulness of including the analysis of 226Ra analysis of other nuclides in the chain of radioactive decay of 238U (238U - 234U - 230Th) to determine the weathering rate in a well-defined system. Nevertheless, the study of the Brahmaputra system shows that proposed method needs to be refined as the sediment transfer is a complex process due to the mineralogical variability, size and (local) dynamics of sediments samples collected

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17

Preiss, Nicolas. "Etude du 210Pb d'origine atmosphérique dans l'air, la neige, les sols et les sédiments : mesures, inventaires et interprétation à l'échelle globale." Phd thesis, Grenoble 1, 1997. http://tel.archives-ouvertes.fr/tel-00765239.

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L'étude présentée ici concerne la répartition du 210Pb atmosphérique à l'échelle globale dans l'environnement. Ce travail débute par une étude expérimentale concernant les mesures de flux de dépôt atmosphérique de 210Pb dans les pluies, les sols et la neige. Une base de données a ensuite été construite en regroupant les mesures effectuées ces quatre dernières décennies. Celle-ci se focalise sur les concentrations de 210Pb dans l'air de surface et sur les flux de dépôt d'origine atmosphérique mesurés aux interfaces atmosphère-surface terrestre (collecteurs artificiels, sols et neige) et eau-sédiment. Cette base de données est ensuite exploitée. Les données de 210Pb atmosphérique sont analysées qualitativement en termes de transport (circulation atmosphérique) et de mécanismes de dépôt, et utilisées quantitativement pour la validation d'un modèle de circulation générale (GCM). En dernière partie, les données de flux de dépôt de 210Pb à l'interface eau-sédiment sont comparées statistiquement aux données de flux de dépôt atmosphérique. Cette comparaison est appliquée à l'étude des transferts entre l'atmosphère et les sédiments et permet ainsi de distinguer quatre différents types de réservoirs aquatiques.

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18

Gemmell, Sally L. G. "Sediment transfer from gravel bed rivers to beaches." Thesis, University of Glasgow, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274782.

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19

Cox, Jonathan M. S. "Coastal-estuary sediment transfers : geochemical and mineralogical study of sources." Thesis, University of East Anglia, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302079.

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20

Adair, Susan Elizabeth. "Proglacial fluvial sediment transfer dynamics at Midre LoveÌnbreen, Svalbard." Thesis, Royal Holloway, University of London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.404957.

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21

Weber, Sofie Aimee. "Contaminant transport and mass transfer to runoff including infiltration." Thesis, The University of Arizona, 1997. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_etd_hy0151_sip1_w.pdf&type=application/pdf.

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22

Young, Adam. "Sediment Processes Influencing the Coastline of Kouchibouguac National Park, New Brunswick." Thesis, Fredericton: University of New Brunswick, 2012. http://hdl.handle.net/1882/35658.

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Parks Canada focuses its tourism and conservation efforts in Kouchibouguac National Park along the park's diverse coastline made up of a variety of sensitive ecosystems including salt marshes, stream estuaries and a shifting barrier island lagoon system. The dynamic sediment processes in the park are not fully understood, making it difficult for Parks Canada to make informed decisions as sea-level rise in the region accelerates. In this study, extensive field data were collected in two sediment zones bordering the Kouchibouguac Lagoon. Stream data were collected and used to estimate the monthly average sediment load entering the lagoon. The maximum and minimum monthly average sediment loads were 130 g/s and 11 g/s in April and September, respectively. These freshwater sediments pass through estuaries to deposit at the coastline of the park. Changes in the barrier system surrounding the tidal inlet Little Gully were also monitored over 15 months using modern surveying techniques. The surveys showed a general southward shift in the study area and a landward migration of sediments within the flood tidal delta of the inlet. Dune surface area, volume, and vegetation cover were also examined, and the critical shear stress and velocity of the sediments were calculated. The field investigations revealed that the Kouchibouguac Lagoon was gradually filling in with sediments during the study. It is recommended that a permanent hydrometric station be installed in one of the major streams in the park and that future research along the coastline of the park complement Parks Canada's current monitoring program for the barrier island system.

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23

Lapham, Wayne Wright, and Wayne Wright Lapham. "Conductive and convective heat transfer in sediments near streams." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/191144.

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An Fourier Series solution is presented that describes the simultaneous, one-dimensional, vertical flow of heat and ground water in homogeneous, porous media beneath streams. Use of this analytical solution provides an indirect method of determining vertical flow rates and the effective vertical hydraulic connection between sediments and overlying streams. The method consists of varying the Darcy velocity in the solution until the temperature profiles predicted by the solution match those measured in the field. The method was applied at three field sites in Central Massachusetts. At the first site, which is underlain by lacustrine clay, the vertical flow rate through the clay was determined to be less than 5x10⁻⁷ cm/s and the vertical hydraulic conductivity was less than 0.08 cm/s. The vertical flow rate through mixed sand and gravel underlying the second site equaled 7.5x10⁻⁶ cm/s and vertical hydraulic conductivities of sediments underlying the site ranged from 3.8x10⁻⁴ to 3.1x10⁻³ cm/s. The vertical flow rate through mixed sand and gravel underlying the third site ranged from 3x10⁻⁵ to 7x10⁻⁵ cm/s and vertical hydraulic conductivities of sediments underlying the site ranged from 1x10⁻³ to 4x10⁻³ cm/s. The simultaneous flow of heat and ground water in sediments beneath streams may be more complex than that assumed for the Fourier Series solution. The additional complexity may be partially attributable to two factors: the presence of horizontal ground-water flow, and the presence of thermal conditions near the stream that differ from conditions in the stream itself. The effects of that these two factors have on thermal regimes in sediments beneath streams were investigated using numerical simulations. Results indicate, for example, that under conditions of no horizontal ground-water flow, thermal conditions near the stream can affect temperatures in sediments beneath the stream as far as 900 cm from the stream bank. For horizontal flow rates greater than about 1x10⁻⁴ cm/s, thermal conditions near the stream can affect temperatures in sediments beneath the stream as far as 1500 cm from the stream bank. The method of determining flow rates and hydraulic connection has been applied to stream-aquifer systems. However, the method also may have application in other hydrologic settings. Two such applications might be to determine flow rates to and from lakes and rates of recharge to aquifers.

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24

Nyander, Annie. "River bed sediment surface characterisation using wavelet transform-based methods." Thesis, Edinburgh Napier University, 2004. http://researchrepository.napier.ac.uk/Output/5885.

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The primary purpose of this work was to study the morphological change of river-bed sediment surfaces over time using wavelet transform analysis techniques. The wavelet transform is a rapidly developing area of applied mathematics in both science and engineering. As it allows for interrogation of the spectral made up of local signal features, it has superior performance compared to the traditionally used Fourier transform which provides only signal averaged spectral information. The main study of this thesis includes the analysis of both synthetically generated sediment surfaces and laboratory experimental sediment bed-surface data. This was undertaken using two-dimensional wavelet transform techniques based on both the discrete and the stationary wavelet transforms. A comprehensive data-base of surface scans from experimental river-bed sediment surfaces topographies were included in the study. A novel wavelet-based characterisation measure - the form size distribution ifsd) - was developed to quantify the global characteristics of the sediment data. The fsd is based on the distribution of wavelet-based scale-dependent energies. It is argued that this measure will potentially be more useful than the traditionally used particle size distribution (psd), as it is the morphology of the surface rather than the individual particle sizes that affects the near bed flow regime and hence bed friction characteristics. Amplitude and scale dependent thresholding techniques were then studied. It was found that these thresholding techniques could be used to: (1) extract the overall surface structure, and (2) enhance dominant grains and formations of dominant grains within the surfaces. It is shown that assessment of the surface data-sets post-thresholding may allow for the detection of structural changes over time.

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25

Reid, Simon Christian. "Coarse sediment delivery and transfer within an upland gravel-bed river environment." Thesis, University of Leeds, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.414171.

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26

Ballantine, Deborah Jayne. "The implications of the catchment sediment budget for phosphorus transfers in river basins." Thesis, University of Exeter, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426163.

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27

Smart, Martin James. "Deglaciation dynamics of the Feegletscher Nord, Switzerland : implications for glacio-fluvial sediment transfer." Thesis, University of Hertfordshire, 2015. http://hdl.handle.net/2299/17094.

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Understanding of the processes of sediment transfer within, and from, glaciated catchments is of fundamental importance in order to establish rates of sediment transfer and resultant landscape evolution. Rates of glacio-fluvial sediment transfer are strongly controlled by glacier meltwater runoff and the availability of sediments for entrainment. However, it is becoming apparent that recently deglaciated forefields can modify the patterns of suspended sediment transfer. Glacier shrinkage exposes areas of unstable glacigenic sediments that can be subject to reworking and redistribution, and, as these environments become ice-free, heightened levels of geomorphological activity (so-called 'paraglacial' activity) are also likely to have a significant impact on both sediment and water yields from deglaciating catchments. Consequently, questions are raised as to the impacts of deglaciation upon contemporary and future rates of suspended sediment transfer, and the resultant fluvial sediments loads and rates of landscape adjustment. Therefore, the aim of this research was to present an integrated study of how sediment transfer in a glaciated catchment functions during, and is responding to, deglaciation. A variety of techniques were employed to examine the hydrological functioning of an Alpine glacier, the Feegletscher Nord, Switzerland, and the resultant temporal and spatial patterns of sediment transfer in light of catchment hydrology, ablation processes and forefield geomorphology. Data was collected over two field campaigns in 2010 and 2012 to capture the inputs, throughputs and outputs of meltwater and sediment. This research found that patterns of sediment transfer were modified within the proglacial zone, reinforcing previous findings that the location of proglacial monitoring is important in determining the observed patterns of sediment transfer. These patterns of sediment transfer were attributed to variations in forefield sediment availability, which appeared to demonstrate marked spatial variability. This variability was hypothesised to be influenced by the geomorphological characteristics of the forefield, including rock fall debris that appeared to limit sediment availability, and glacigenic sediment deposits that enhanced the availability of in-channel and channel-marginal sediments. These findings suggest that the investigation of rates of sediment transfer and paraglacial sedimentation may be complicated in catchments that have experienced complex geomorphological responses to deglaciation. In addition, the investigation of sediment transfer processes and the development of a glacier runoff model enabled the exploration of future suspended sediment loads with progressive deglaciation and a changing climate. Suspended sediment loads were predicted to experience rapid declines until the end of the 21st Century due to reductions in meltwater runoff as glacier extent is reduced. However, it is suggested that uncertainties in future sediment availability limit the usefulness of such forecasts. Consequently, this research highlights how the understanding of both sedimentary and hydrological processes in glaciated catchments may be enhanced by consideration of the changes that can occur in these environments associated with glacier shrinkage and a changing climate.

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28

Romas, Lisa. "Functional identification of microorganisms that transform mercury in marine sediments." Wright State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=wright1278616625.

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29

Hodson, Andrew. "Climate, hydrology and sediment transfer process interactions in a sub-polar glacier basin, Svalbard." Thesis, University of Southampton, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241002.

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30

Orr, Elizabeth N. "''Deciphering tectonic and climatic controls on erosion and sediment transfer in the NW Himalaya''." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1560866634385041.

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31

GHAITH, AFIF. "LEBANESE SUBMARINE CANYONS AND THEIR ROLE IN SEDIMENT TRANSFER FROM SHALLOW TO DEEP WATER." Doctoral thesis, Università degli studi di Ferrara, 2020. http://hdl.handle.net/11392/2488030.

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Submarine mass movements and their consequences are of major concern for coastal communities and infrastructures but also for the exploitation and the development of seaﬂoor resources. Elevated awareness of the need for better understanding of the underwater mass movement is coupled with great advances in underwater mapping technologies over the past two decades. The seaﬂoor in the Bay of Jounieh and Beirut North (Lebanon) is characterized by deep canyons, reaching one thousand meters depths in proximity of the coast. Signs of submarine mass movement instability related to these canyons create a connection between shallow and deep water. The presence of these canyons in a tectonically active area generates a particular drained mechanism to the sediment in form of mass movement and slumping. Since this area is poorly explored, in the framework of an international project between Lebanese Navy Hydrographic Service, Lebanese National Center for Marine Sciences, University of Ferrara and Italian Navy Hydrographic Institute, we analyse the morpho-bathymetric and sedimentological characters of the coastal and shelf sectors. Multibeam echosounder and sub-bottom proﬁler acoustic systems calibrated with ground truths (sediment grabs) in accordance to the International Hydrographic Standards allow us to characterize the nature of seaﬂoor and sub-seaﬂoor. The detection of particular undersea features provides detail maps which are in support to littoral morpho-dynamics, coastal transport and sediment budget. This high resolution multibeam bathymetry dataset, integrated by the sedimentological characters, will provide useful constraints to the potential natural hazards that may be caused by active tectonics in the offshore and a high coastal risk in one of the most populated region of Lebanon. The study aims to evaluate the role of the area's submarine canyons in the underwater mass movements, taking into account: 1) the evaluation of the environmental condition of the Jounieh Bay, 2) the sediment deposit dynamics along and across the Lebanese continental shelf and slope, and finally 3) the sediment movement inside canyons heads in the Jounieh-Beirut Basin. The above studies allowed us to discover that although canyons in the research's area belong to the same continental margin, share more or less the same morphology and are located few kilometres apart, they display a relevant variability in their geometry, morphology, sedimentary processes, and where the SW current is the main governing cause of sediment movement, and to highlight the important role that the Jounieh-Beirut Basin plays in the Lebanese underwater dynamics, comparing its status in 2019 with a previous work achieved by Goedicke and Sagebiel (1976).
I movimenti di massa sottomarini con le loro conseguenze sono di un grande interesse per le comunità e le infrastrutture costiere e anche per lo sfruttamento e lo sviluppo delle risorse del fondale marino. L’elevata consapevolezza della necessità di una migliore comprensione del movimento di massa sottomarino è accompagnata da grandi avanzamenti nelle tecnologie di rilievi sottomarini durante gli ultimi due decenni. Il fondale marino nella baia di Jounieh e del Nord di Beirut (Libano) è caratterizzato dalla presenza di profondi canyons che raggiungono mille metri di profondità in prossimità della costa. I segni dell’instabilità del movimento di massa sottomarino relativi a tali canyons creano una connessione tra acque basse e acque profonde. La presenza di questi canyons in un’area tettonicamente attiva genera un particolare meccanismo di drenaggio del sedimento sotto la forma di movimento di massa e di crolli. Visto che l’area è poco esplorata, nel contesto di un progetto internazionale tra il servizio idrografico della Marina Libanese, il centro nazionale libanese per le scienze del mare, l’Università di Ferrara e l’istituto idrografico della Marina Militare Italiana, analizziamo i caratteri morfo-batimetrici e sedimentari dei settori costieri e della piattaforma continentale. Gli ecoscandagli multifasci ed i sistemi acustici ‶Sub-bottom profilers″, calibrati con dati reali (raccolta di sedimenti), in conformità con gli standard internazionali dell’idrografia, ci permettono di caratterizzare la natura del fondale e del sotto fondale. La rivelazione di oggetti sottomarini particolari fornisce delle mappe di dettaglio a supporto di analisi di morfodinamica litorale, trasporto costiero e budget sedimentario. Questi dati batimetrici da sistemi multifasci di alta risoluzione, integrati con i caratteri sedimentologici, forniscono dati utili per potenziali rischi naturali che potrebbero essere causati da tettonica attiva nella zona offshore, e per un alto rischio costiero in una delle regioni le più popolate del Libano. Questo studio ha lo scopo di valutare il ruolo dell’area dei canyons sottomarini nei movimenti di massa sottomarini, considerando: 1- La valutazione della condizione ambientale della baia di Jounieh. 2- Le dinamicità del deposito sedimentario lungo e attraverso la piattaforma continentale e lo slope libanese e finalmente, 3- Il movimento del sedimento nelle teste dei canyons nel bacino Jounieh-Beirut. Questi studi ci hanno permesso di scoprire che i canyons nell’area di ricerca nonostante la loro appartenenza allo stesso margine continentale, la condivisione più o meno della stessa morfologia e la loro presenza a pochi chilometri l’uno a altro, mostrino una relativa variabilità nella loro geometria, morfologia, e processi sedimentari, la corrente SW è la causa principale che controlla il movimento del sediment. Lo studio evidenzia il ruolo importante che il bacino di Jounieh-Beirut gioca nella dinamicità sedimentaria dei fondali libanesi, anche grazie al confronto tra il suo stato attuale (2019) e la situazione nel 1976.

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32

Zhang, Li. "Clay Minerals Supporting Microbial Metabolic Activities in Natural Sediments." Miami University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=miami1564142598119446.

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33

Cakiroglu, Ayse Idil. "Salinity Inference In Inland Turkish Shallow Lakes On Paleoecology Using Sub-fossil Cladocera." Phd thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615450/index.pdf.

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In the current study, sub-fossil Cladocera collected from the surface sediment of 44 shallow lakes spanning over five latitudes from north to south of Turkey using snap-shot methodology revealed strong impact of salinity on cladoceran community structure. To see the whole picture, sediment cores collected from six of the lakes and long-term monitoring data from two of the lakes were also investigated. Contemporary cladocerans and sub-fossil assemblages were compared to reveal that their responses to salinity changes were highly similar. This lead us to use sub-fossil cladocerans and salinity data from water column together while generating the calibration data set using ordination techniques. Salinity transfer function models were developed utilising weighted averaging techniques. The developed salinity transfer function was applied to cladocera assemblages from dated sediment cores. Hindcasting of the salinity inference model was performed using monitoring data and the reconstructed salinities from two central Anatolian lakes and reflected good linear correlation with the known lake salinity history. This thesis has confirmed that sub-fossil Cladocera is a valuable indicator of historical salinity change and marker for the monitoring of lakes. For the first time, the lake environmental variables and sub-fossil cladoceran species composition from the surface sediments of Turkish shallow lakes were studied and a salinity transfer function was developed to elucidate past salinity change. The approach of the current study has been proven to be reliable while interpreting past salinity conditions. Since monitoring programmes are scarce in Turkey, paleolimnological analyses would be beneficial especially when defining effective restoration strategies.

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34

Rouse, Helen Louise. "The development of a transfer function relating surface waves to bedload gravel transport using the self-generated noise technique." Thesis, University of Hull, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265126.

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35

Scott, Christine Helen. "Contemporary sediment transfer in Himalayan glacial systems : implications for the interpretation of the Quaternary record." Thesis, University of Leicester, 1992. http://hdl.handle.net/2381/34498.

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This thesis presents the results of an investigation of the glacial geomorphic processes associated with sediment production and deposition in the Nanga Parbat Massif, Pakistan Himalaya. Emphasis is placed on contemporary deposition mechanisms; the nature and timing of Quaternary glaciation; and the influence of tectonic uplift on the glacial record. The field study concentrated on the extensive valley glacier systems of the Nanga Parbat Massif (8125 m.a.s.l.), at the western end of the Himalayan mountain chain. Some 60% of the surface of this region is glacierized and has experienced rapid tectonic uplift and intense denudational processes throughout the Quaternary. The glaciers of the area are very active; they have high values of mass-flux and transport considerable volumes of surficial glacial debris. Past and present glacial activity has resulted in the extensive moraines and other glacier-related deposits which are found throughout the massif. Sampling was undertaken on both contemporary and Pleistocene glacial deposits. Systematic sampling of glacier sediments of the Rakhiot Glacier to the north of the massif and the Chungphar Glacier to the south was designed to sample down-glacier trends. Transport pathways, from sources areas to the glacier snout, were mapped and samples were collected for particle size analysis and scanning electron microscopy. A similar study of the Glacier de Cheilon in the Swiss Alps was also completed so that the two glacier sediment systems could be compared. In the Nanga Parbat Massif, the Quaternary deposits of the Rupal, Astor, Rama and Rakhiot valleys were sub-divided into sedimentary units on the basis of geomorphological mapping, logging of sedimentary sections and multi-parameter relative age dating techniques. Quaternary ELAs and glacial limits were reconstructed in an attempt to assess variations in the size and distribution of glaciers in the massif. Debris transport in the supraglacial zone is an important contributor to contemporary glacial sediment production. Transport of the thick supraglacial debris results in intense comminution producing large volumes of fine sediment. This is reflected in positive down- glacier trends in sediment fining and increased particle weathering. This finding challenges the traditional view that the basal zone of traction is the only major source of fine sediment production in glacial environments. Fine sediment is also produced outside the immediate glacial zone, by intense weathering of the exposed mountain rockwalls. Important contributions from supraglacial, subglacial and non-glacial sources explain the fines-rich nature of the glacial meltwaters which drain the massif. The importance of supraglacial debris transport is a striking characteristic of the contemporary glacial depositional system, the dominant mode of glacial deposition being the dumping of supraglacial debris in ice-marginal locations. Mass movement is an important mechanism in the depositional process as is resedimentation; resulting in complex suites of ice-marginal deposits. Broadly synchronous glacier expansion in the Pleistocene resulted in a maximum lowering of the ELA of between 900 and 1000 m, with glacier termini on the east of the massif being lowered to altitudes of 2100 m and those on the north descending to join the Indus valley at 1800 m. Mountain ice caps and piedmont valley glaciers were much thicker in the Pleistocene, filling the valley systems. Present day glaciers are a remnant of these much more extensive Pleistocene valley glacier systems. Retreat during the late Pleistocene was roughly synchronous throughout the massif with glaciers becoming increasingly confined to the floors of the valleys. The present steep relief is a result of the combination of Quaternary bedrock uplift, in the form of tectonic uplift and isostatic response to glacial unloading, and over- deepening by glacial erosion during the Pleistocene. It appears that the glacial sediment systems of the Nanga Parbat massif have changed markedly over the Quaternary with large low gradient piedmont glaciers giving way to small, steep glaciers with thick supraglacial debris covers. Retreat of Pleistocene glaciers exposed large areas of bedrock to rapid subaerial weathering with the supraglacial debris component became increasingly important in the sedimentary system.

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36

Wathen, Simon John. "The effect of storage upon sediment transfer processes in a small Scottish gravel-bed river." Thesis, University of St Andrews, 1995. http://hdl.handle.net/10023/3844.

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A detailed morphological approach is used to determine the effect of storage location upon sediment mobility, providing partial explanation for previously reported non systematic characteristics of sediment transfer. Data were collected over a period of 2 years from a small river in the Highlands of Scotland. Sediment transfer fluxes and volumetric storage were measured using an integrated data collection programme utilising 990 magnetic tracers and 225 cross sections spaced at c1 m intervals over two contrasting reaches (A and B). Scaled tracer fluxes were monitored between 6 numerically defined storage types (very active, active, semi active, stable, inactive and dormant). Storage characteristics were determined using response time, defined as the time at which cumulative output from a store exceeds sediment in storage. Activity progressively declined from very active to inactive stores, the exact magnitude being a function of local morphology, particularly the presence of fixed bars. Inter store exchanges of sediment were assessed using descriptive matrices categorised into individual types according to transfer and storage proportions. A relative dimensionless shear stress scale used to differentiate the storage conditions responsible for the occurrence of each matrix type indicated that transfer in reach A is a function of hydraulic conditions, grain size and storage, in reach B grain size is the only dominant factor. These controlling factors were subdivided into peak stage, duration, relative and absolute grain size, morphology and burial and assessed with reference to fractional transfer distances. The relative importance of each factor to transfer depends upon storage location and the incidence of morphological change. Comparison between tracer and volumetric fluxes provides explanation for sediment transfer distributions and allows assessment of morphological controls upon channel pattern maintenance. The results from this study were summarised in two conceptual models describing downstream and within reach sediment transfer.

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37

Gravelle, Richard. "Temporal variability of meltwater and sediment transfer dynamics at an Arctic glacier, Storglaciären, northern Sweden." Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/14412.

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In glacierised regions, suspended sediment fluxes are highly responsive to climate-driven environmental change and can provide important information regarding the relationships between glacier variations, climate and geomorphic change. As a result, understanding patterns of suspended sediment transport and their relationship with meltwater delivery is of critical importance. However, studies of glacial suspended sediment transport are often limited by interpreting patterns of suspended sediment transfer based on whole-season data, allowing precise patterns to become masked. This thesis aims to contribute to the understanding of suspended sediment transfer in glacierised basins through the investigation of patterns of suspended sediment delivery to the proglacial area of Storglaciären, a small polythermal valley glacier located in the Tarfala valley, Arctic Sweden. High temporal resolution discharge and suspended sediment concentration data were collected during two summer field campaigns at Storglaciären. Interpretations of suspended sediment transport data were made using diurnal hysteresis and sediment availability data, combined with suspended sediment shape and magnitude data classified by applying principal component and hierarchical cluster analyses. Analysis of the dominant discharge generating processes at Storglaciären was also conducted using principal component analysis, allowing patterns of discharge to be better understood. This was complemented by analysis of the structure and evolution of the glacier drainage system by linear reservoir modelling and flow recession analysis. The results suggest that patterns of discharge and suspended sediment transport at Storglaciären are complex, with distinct processes and magnitudes of transport evident at both proglacial outlet streams, Nordjåkk and Sydjåkk. These processes are intrinsically linked to meteorological variables, with both ablation-driven and precipitation-driven discharge exerting influence over patterns of suspended sediment transport in the proglacial area of Storglaciären.

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Diaz, Mélanie. "Modélisation numérique des transferts sédimentaires de l'estuaire de la Gironde au plateau continental." Thesis, Brest, 2019. http://www.theses.fr/2019BRES0095.

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Les matières en suspension (MES), vecteur principal des nutriments et contaminants apportés par les grands fleuves, peuvent directement influencer le fonctionnement des écosystèmes marins ainsi que la qualité des eaux littorales. L’étude de leur dynamique s’avère donc essentielle dans le cadre de la protection des ressources marines. Cependant, l’analyse du devenir du matériel particulaire d’origine continentale au travers d’un estuaire est complexe de par la pluralité des processus physiques, sédimentaires et biogéochimiques qui s’y développent, à la fois dans les domaines intra-estuariens et côtiers. Dans le cadre du projet ANR AMORAD, cette étude vise à contribuer à l’amélioration de la compréhension des flux de matières potentiellement contaminées, issues principalement des apports terrigènes délivrés par les estuaires. L’objectif principal est d’aborder la problématique liée aux transferts de particules fines de l’estuaire de la Gironde au plateau continental, principalement par une approche de modélisation numérique, pour : (i) analyser l’influence des évènements hydrométéorologiques (crue/étiage, tempêtes) sur les flux particulaires ; et (ii) déterminer les zones privilégiées d’accumulation ou de dispersion des sédiments potentiellement contaminés sur le plateau continental, et notamment le rôle de la vasière Ouest Gironde dans le piégeage de ceux-ci. Dans ce but, un modèle hydrosédimentaire 3D réaliste, reposant sur le modèle hydrodynamique MARS3D, le modèle de vagues WAVE WATCH 3® et le module sédimentaire MUSTANG, a été mis en place sur l’estuaire de la Gironde et le plateau continental adjacent. Grâce à une étude de sensibilité du modèle au paramétrage sédimentaire, les incertitudes sur les flux sédimentaires à l’embouchure de l’estuaire ont été quantifiées. En s’appuyant sur l’étude de sensibilité et sur l’analyse de la durée de spin-up nécessaire à la stabilisation du modèle, le modèle a été calibré de l’estuaire au plateau. Celui-ci a démontré des performances et un niveau de validation satisfaisants, avec une robustesse des flux et couvertures sédimentaires sur 6 ans remarquable. L’étude de la dynamique sédimentaire résiduelle a révélé une forte influence de la circulation barocline sur les échanges de sédiment à l’embouchure de l’estuaire, favorisant l’import de sédiment dans l’estuaire en période humide. L’exploitation du modèle a également permis d’étudier les zones d’accumulation privilégiée des sédiments et, plus particulièrement, les conditions de stockage associées aux forçages hydrométéorologiques dans la vasière Ouest Gironde. L’efficacité du piégeage est négativement corrélée avec l’action des vagues (i.e. érosion) et positivement corrélée avec le débit fluvial (i.e. accrétion). En moyenne, environ 25% des vases exportées de l’estuaire sont stockées dans la vasière
Estuaries are major vectors of sediment (i.e. mud and sand) transfer between terrestrial environments and the seas. Contaminants, mostly arising from human activities along the shores, are potentially adsorbed on fine particles and transported to the sea through estuaries. Therefore, studying sediment dynamics in these zones is crucial for marine resource protection. However, the complexity of physical, biochemical and sedimentary processes taking place along the interfacial areas represent a highly challenging topic. The PhD project takes place in the framework of the ANR AMORAD project, which aims at improving understanding and numerical modeling of potentially contaminated sediment fluxes from continental areas to the sea. Thus, based on the Gironde Estuary study site and its adjacent continental shelf, this PhD thesis focuses on: (i) investigating the influence of hydro- meteorological events on sediment fluxes and (ii) determining the sediment accumulation and dispersion areas on the continental shelf and especially the role of the West Gironde Mud Patch on continental sediment trapping. To this end, a realistic 3D numerical model, based on the MARS3D hydrodynamic model, the WAVE WATCH 3® wave model and the MUSTANG sediment module, has been implemented on the Gironde Estuary and the adjacent continental shelf. Based on a sensitivity analysis to sediment parameterization, the uncertainties on sediment fluxes at the estuarine mouth have been quantified. Moreover, based on the previous sensitivity analysis and on the study of the spin-up period required for model stabilization, the latter has been calibrated from the estuary to the shelf. It has demonstrated a satisfactory validation state with good performance compared to observed SSC, and a remarkable robustness of sediment flux and distribution over 6 years. The study of residual sediment dynamics revealed a strong influence of baroclinic circulation on sediment exchanges at the estuary mouth, with enhanced sediment import into the estuary during wet season. Further analyses made it possible to study the areas of sediment accumulation and, more particularly, the storage conditions associated with hydro-meteorological forcing in the West Gironde mudflat. Trapping efficiency is negatively correlated with wave action (i.e. erosion) and positively correlated with river flow (i.e. accretion). On average, about 25% of the mud exported from the estuary is stored in the West Gironde Mud Patch

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Garrett, Rhiannon Pamela. "Constraining upland erodibility and marine deposition: source-to-sink sediment transfer in the Gulf of Papua." Thesis, University of Sydney, 2020. https://hdl.handle.net/2123/24021.

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The Papua New Guinean (PNG) landscape is young and rapidly evolving, with high uplift rates and precipitation rates that exceed 10 m/yr producing high erosion rates. Consequently, the Gulf of Papua, an active foreland basin in southern PNG, receives a large terrigenous sediment flux of ~384 Mt/yr. The fresh and tectonically active Papuan landscape makes the Gulf an ideal location for studying tectonic and climatic impacts on source-to-sink surface processes and basin stratigraphy. This thesis aims to (1) constrain a range of parameters, including tectonic uplift rates, upland erodibility and marine sediment distribution, in order to calibrate a numerical model simulating the Late Quaternary landscape evolution of the Gulf of Papua foreland basin. In addition, this study aims to (2) use the calibrated model to identify temporal and spatial patterns in erosion, fluvial sediment transportation and sediment distribution and composition in the basin. This thesis uses the open-source landscape evolution code Badlands to simulate surface processes in PNG. However, to simulate source-to-sink sediment transfer in the Gulf of Papua it was first necessary to constrain a range of parameters with tectonic and geological constraints specific to the basin. The magnitude, timing and spatial variations in uplift across the Papuan Peninsula were constrained using the present-day elevation of remnants of late Miocene volcanics that were deposited near sea level during the Miocene and have subsequently been uplifted. To constrain upland erodibilities, a series of simulations of the landscape evolution of the Gulf of Papua were run in Badlands, testing the impact of a range of erodibility coefficients on the sediment flux into the Gulf. The sediment loads of simulated rivers were compared to the present-day natural sediment loads of the Fly, Kikori and Purari Rivers to find both an averaged erodibility coefficient for the Gulf of Papua catchment and lithology-specific coefficients. Comparing simulation results to observed sediment accumulation rates in the deep-sea Gulf assisted in constraining the distribution of sediment in the marine environment in Badlands. The calibrated model was then used to simulate the sediment routing system in the Gulf of Papua catchment. Results show an increase in the Plio-Quaternary uplift rate from negligible at sea level along the south-western coast of the Papuan Peninsula to > 600 m/Myr in the peaks of the Owen Stanley Range. Comparisons with present-day fluvial sediment loads constrain the averaged erodibility coefficient in Badlands for the Gulf of Papua to within the range 5.53 – 7.41 x 10−6 yr−1, with an estimated averaged erodibility coefficient of ~7 x 10−6 yr−1 for a resolution of 500 m. Erodibility coefficients for specific lithologies range from ~6.5 x 10−6 yr−1 for metamorphics and granites to ~13.0 x 10−6 yr−1 for soft sediments. Subsequently, the marine accommodation variable was constrained to within the range 0.005 − 0.009, so that the largest depocentres in the Gulf are on the continental slope. A sensitivity analysis reveals that the simulated sediment flux into the Gulf of Papua is more sensitive to changes in precipitation rate than to changes in the uplift rate. These findings permit the simulation of sediment transfer processes in the Gulf of Papua during the Late Quaternary, informing our understanding of the catchment’s surface evolution and the stratigraphy of the deep sea basin. Simulation results suggest that sediment delivered to the eastern Gulf is largely composed of metamorphics and volcanics sourced from the Owen Stanley Range. Changes in sea level have a limited impact on sediment deposition in the east as the narrow, steep continental shelf allows rivers to deliver sediment directly into the deep-sea depocentres, which are compositionally distinct from one another. The mature rivers in the west of the catchment transfer sediment derived from soft sediment, mafics, metamorphics and granites in the Papuan Orogen to the western Gulf of Papua. Marine transgression and highstand in the last 14 Kyr have submerged the wide continental shelf in the western Gulf and prevented rivers from delivering sediment directly into the deep sea. Thus, there has been increased sediment accumulation on the submerged shelf. These results highlight basin morphology, the surface distribution of lithologies and the glacio-eustatic cycle as major controls on the sediment distribution and composition in the marine environment.

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Ding, Xuesong. "Towards sequence stratigraphy 2.0: Dynamic topography, sea level change and sediment transfer from source to sink." Thesis, The University of Sydney, 2019. http://hdl.handle.net/2123/20665.

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Earth’s sedimentary successions are an archive of past climatic and tectonic events and sea level changes by recording the complex interactions between those processes across a wide range of time and space scales. Numerous efforts have been made to decipher this archive to obtain signatures of deep Earth dynamics (e.g. dynamic topography induced by mantle flow). However, it remains a challenge as the signals generated by dynamic topography are usually concealed by signals generated by plate tectonic processes. Sequence stratigraphy is an effective tool to analyse sedimentary units. Recently, quantitative stratigraphic analysis has been used to achieve more precise interpretations, which will likely advance the quantification of the role of controlling factors in shaping stratigraphic record. This thesis consists of two parts. The first part presents stratigraphic modelling using the surface process code pyBadlands and quantitative stratigraphic interpretations based on two well-established techniques: the trajectory analysis and the accommodation succession methods. This numerical framework contributes to the development of quantitative sequence stratigraphy which is an important component of “sequence stratigraphy 2.0”. The second part further investigates the large-scale and long-term drainage and sedimentary responses to dynamic topography. Our models predict distinct erosional and depositional landscapes, comparing with that induced by eustatic sea level changes, which provides insights into differentiating the geological signals induced by dynamic topography in tectonically-stable regions. The propagating wave of positive dynamic topography under a plateau produces a landscape that is comparable to southern Africa during Cretaceous times. The propagating wave of negative dynamic topography tilts the surface and generates depositional patterns similar to the continental interior of North America during Cretaceous times and South America during Miocene times.

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Causse, Jean. "Temporalité des transferts de nutriments dans les bassins versants à algues vertes." Thesis, Rennes 1, 2015. http://www.theses.fr/2015REN1B012/document.

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En Bretagne, les « marées vertes » sont récurrentes depuis le début des années 70 et occupent une place importante dans le débat public en terme sanitaire, politique et économique. Lors de cette thèse, une large revue bibliographique a été réalisée sur l’export d’azote et une méthodologie innovante a été mise en place afin d’étudier la variabilité spatio-temporelle de l’export de nutriments dans 2 bassins versants à algues vertes à une échelle intra-annuelle et pendant des évènements extrêmes (évènements pluvieux, période touristique de basses eaux,…). Les bassins versants sélectionnés pour les expérimentations de terrain sont l’Ic et le Frémur (Côtes d’Armor). 3 types d’expérimentations ont été réalisées sur ces bassins versants : 1) Des campagnes de prélèvements ponctuels par temps sec et par temps de pluie (32 stations, 27 campagnes) ; 2) des prélèvements automatiques en crue (3 stations, 8 crues) ; et 3) la mesure haute fréquence (2 stations, en continu). Les paramètres hydrologiques et physico-chimiques classiques, les matières en suspension, les spectres UV et toutes les formes de macronutriments (carbone, azote, phosphore) ont été analysés lors de ces expérimentations. Les résultats obtenus confirment pour une part un certain nombre de résultats de la littérature. D’autre part, il met en lumière la relation carbone/nitrates, jusqu’à présent peu étudiée à différentes échelles spatio-temporelles et pendant des évènements pluvieux, qui semble pourtant primordiale dans la compréhension des phénomènes d’export de nitrates à l’échelle de l’année. Enfin, l’analyse de toutes les formes de nutriments révèle l’importance des formes particulaires issues de l’érosion des sols. Ces résultats soulèvent de nombreuses questions de recherche qui mériteraient un approfondissement afin d’améliorer la connaissance des transferts de nutriments dans les bassins versants et prioriser les actions de remédiations. Les perspectives de ce travail sont à la fois scientifiques et pratiques. Au niveau scientifique, les efforts de recherche sur la relation carbone/nitrate et l’identification de la fraction de carbone organique assimilable par les organismes dénitrifiants doivent être poursuivis. De même, l’amélioration des connaissances sur l’export de nutriments en crue passe par l’identification précise des sources de nutriments particulaires pendant les crues printanières. Au niveau pratique, il doit contribuer à l’amélioration des pratiques agricoles, à la reconnaissance de l’intérêt des zones humides naturelles et à l’amélioration des types de traitement utilisés par les stations d’épuration. Les résultats obtenus lors de cette étude devraient notamment être mis en relation avec la dynamique des nutriments observée dans l’estran pendant la période de développement des algues vertes. Enfin, un effort d’amélioration de l’accès à certains type de données sur les bassins versants est nécessaire afin d’améliorer la compréhension des transferts de nutriments
In Brittany (Western France), "green tides" are recurrent since the early 70s and have an important place in public debate in health, political and economic terms. In this thesis, a wide bibliographic review was performed on the export of nitrogen, and an innovative methodology has been set up to study the spatial and temporal variability of nutrient export in two coastal watersheds on an intra-annual basis and during extreme events (rainfall events, tourist periods of low water, ...). Watersheds selected for the field experiments are Ic and Frémur (Côtes d'Armor). 3 types of experiments were performed on these watersheds: 1) Campaigns of grab samples by dry and wet weather (32 stations, 27 campaigns); 2) automatic sampling during floods (3 stations, 8 floods); and 3) high frequency measurement (2 stations, continuous). Conventional hydrological and physicochemical parameters, suspended solids, UV spectra and all forms of macronutrients (carbon, nitrogen, phosphorus) were analyzed during these experiments. The results confirm in part a number of results of the literature. Furthermore, it highlights the relationship carbon / nitrates far little studied at different spatial and temporal scales and during rainfall events, which however seems to be crucial in understanding of nitrate export. Finally, the analysis of all forms of nutrients reveals the importance of particulate forms from soil erosion. These results raise many research questions that merit further development in order to improve knowledge on nutrient transfers in watersheds and prioritize remediation actions. The prospects of this work are both scientific and practical. At the scientific level, research efforts on the relationship carbon / nitrate and identification of the assimilable fraction of organic carbon by denitrifying organisms must be continued. Similarly, the knowledge on nutrient export must be improved through the precise identification of particulate nutrient sources during the spring floods. On a practical level, it should contribute to the improvement of agricultural practices, the recognition of the interest of natural wetlands and improvement of the types of treatment used by treatment plants. The results obtained in this study should in particular be linked to the dynamics of nutrients in the foreshore observed during the development of green algae. Finally, an effort to improve access to certain types of data on watersheds is needed to improve understanding of nutrient transfers

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MESSAITFA, AMAR. "Transfert d'eau, des sediments et des polluants associes sur le bassin de l'ill : cas du mercure." Strasbourg 1, 1997. http://www.theses.fr/1997STR13148.

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Le bassin versant de l'ill, est pollue par les metaux lourds, notamment le mercure, suite aux rejets industriels sur la thur. Les mesures effectuees sur l'axe fluvial thur-ill au cours de quatre missions montrent que le mercure est plus concentre dans les matieres en suspension (mes) et les sediments de fond (sf) que dans les phases dissoutes ou sa teneur est souvent inferieure a la limite de detection (5 ng). Les variations de concentration observees sont controlees par la teneur en mercure dans le rejet industriel, par les conditions hydroclimatologiques et par la physico-chimie des eaux. En periodes de basses eaux, l'augmentation de la temperature et la faible hauteur de la colonne d'eau dans la riviere favorisent les processus de methylation du mercure adsorbes sur les sf. En periodes de hautes eaux, la teneur en mercure n'est controlee que par des phenomenes de dilution (mes, debits). L'analyse granulometrique des sf montre que les teneurs en mercure dans les differentes fractions sont fortement controlees par la taille des particules. Les concentrations sont plus elevees dans les particules fines (< 50 m : argiles et limons) que dans les fractions grossieres (> 50 m : sables). Mais la distribution totale du mercure dans les sf est aussi controlee par l'abondance des differentes fractions. D'autre part, lorsque la concentration en chlorures augmente dans la riviere, la teneur en mercure diminue dans la phase dissoute et augmente dans les phases particulaires (mes et sf). Au laboratoire, les experimentations que nous avons realisees pour tester l'effet des chlorures sur le mercure en solution suggerent que le mercure peut etre adsorbe sur les (hydr)oxydes de metaux presents dans les sediments. Cependant, en presence de phosphate (na#2hpo#4), il y a competition entre hgcl#4#2#-, les pertes en mercure dans la solution sont alors comprises entre 30 et 60% seulement. Le suivi amont-aval des autres metaux associes ou non a la pollution mercurielle, a permis d'identifier l'origine des metaux (naturelle et anthropique). A l'exception du sr et du zr qui sont plus concentres respectivement dans les fractions grossieres (> 50 m) et dans les limons (2 a 50 m), les autres metaux suivent le meme comportement que le mercure.

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Uber, Magdalena. "Suspended sediment production and transfer in mesoscale catchments : a new approach combining flux monitoring, fingerprinting and distributed numerical modeling." Thesis, Université Grenoble Alpes, 2020. http://www.theses.fr/2020GRALU011.

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L’étude des mécanismes d’érosion hydrique des sols et de transfert de matières en suspension (MES) des bassins versants vers les rivières revêt des enjeux environnementaux et socio-économiques prégnants face à une pression anthropique grandissante et au changement climatique. L'objectif de cette thèse est de comprendre comment la variabilité de la pluie contrôle l’activation de différentes zones sources de MES et la dynamique des flux hydro-sédimentaires dans deux bassins versants méditerranéens de méso-échelle, la Claduègne (42 km²) et le Galabre (20 km2) membres de l’infrastructure de recherche sur la zone critique OZCAR.Dans la première partie, les contributions des zones d'érosion aux MES à l’exutoire de la Claduègne ont été quantifiées à haute résolution temporelle avec une approche low-cost de traçage. Deux ensembles de traceurs (spectres colorimétriques et de fluorescence X) et trois modèles de mélange ont été comparés pour évaluer la sensibilité des contributions de sources à ces choix méthodologiques. Les principales sources de MES identifiées sont les zones de badlands marno-calcaires. Une approche similaire conduite sur le bassin versant du Galabre a mis en avant la dominance des badlands sur molasses dans les flux de MES. La comparaison des traceurs et des modèles de mélange, a montré que les choix méthodologiques génèrent des différences importantes, qui amènent à recommander une approche d’ensemble multi-traceurs-multi-modèle pour obtenir des résultats plus robustes. L’application de cette approche à un grand nombre d’échantillons de MES a souligné l’importante variabilité inter et intra évènements des contributions des différentes sources de MES, soulevant des questions sur les processus hydro-sédimentaires à l'origine de la variabilité des flux de MES.Le concept de connectivité hydrosédimentaire a été testé en posant l’hypothèse que cette variabilité résultait de distributions des temps de transfert des MES très variables contrôlées par i) les caractéristiques inhérentes aux bassins versants comme la localisation des différentes sources de MES et la façon dont elles sont liées à l’exutoire (i.e. connectivité structurelle) et ii) les caractéristiques spatio-temporelles des évènements pluvieux qui activent et impactent les vitesses de transfert (i.e. connectivité fonctionnelle). Ainsi, dans la deuxième partie, un modèle numérique distribué basé sur la résolution des équations de Saint Venant couplé à un module d’érosion multi-sources de MES, a été utilisé pour évaluer les rôles respectifs des connectivités structurelle et fonctionnelle. L’analyse de sensibilité aux choix de discrétisation et de paramétrisation (i.e. seuil d’aire drainée pour distinguer la rivière des versants, valeurs de coefficients de frottement sur les versants et la rivière) a montré que la localisation des sources de MES dans le bassin versant était plus importante que les choix de modélisation à condition que les paramètres soient dans une gamme réaliste et limitée. Un schéma général de réponse temporelle du bassin versant par type de sources a été observé, cohérent avec les résultats de l’approche de traçage et la distribution des distances des sources à la rivière et à l'exutoire. Ce même schéma persiste pour différentes durées ou intensités des précipitations mais devient beaucoup plus variable lorsque des hyétogrammes bimodaux ou des précipitations variables dans l'espace sont appliquées. En outre, la localisation de la pluie par rapport aux sources détermine les contributions moyennes des sources et donc les différences entre les événements de pluie.Les deux approches de traçage des MES et de modélisation numérique se sont avérées complémentaires et leur application combinée présente un fort potentiel pour comprendre comment les interactions entre connectivité structurelle et fonctionnelle contrôlent la dynamique des flux de MES aux exutoires de bassins versants de méso-échelle
The study of soil erosion by water and the transfer of suspended solids from watersheds to rivers is crucial given the environmental and socio-economic issues with regards to growing human influence and the expected intensification of these processes under climate change. The objective of this thesis is to understand how rainfall variability controls the activation of different sediment source zones and the dynamics of hydro-sedimentary flows in two mesoscale Mediterranean catchments, i.e. the Claduègne (42 km², subcatchment of the Ardèche) and the Galabre (20 km2 , subcatchment of the Durance) which are members of the OZCAR critical zone research infrastructure.In the first part, the contributions of the erosion zones to sediment fluxes at the outlet of the Claduègne catchment were quantified at high temporal resolution with a low-cost sediment fingerprinting approach. Two sets of tracers (Color and X-ray fluorescence tracers) and three mixing models were compared to assess the sensitivity of estimated source contributions to these methodological choices. Marly-calcareous badlands were identified as the main sediment source. A similar approach carried out on the Galabre catchment area showed that badlands on molasses were the main source. The comparison of tracer sets and mixing models, showed that the methodological choices generated important differences. Thus, we suggest a multi-tracer-multi-model ensemble approach to obtain more robust results. The application of this approach to a large number of sediment samples highlighted the important within and between event variability in the contributions of different sediment sources, raising questions about the hydro-sedimentary processes that cause this variability.We hypothesized that this variability resulted from variable suspended sediment transit time distributions governed by the interplay of (i) catchment characteristics such as the location of different sources and how they are linked to the outlet (referred to as structural sediment connectivity) and (ii) the spatio-temporal characteristics of rain events that activate and impact transfer velocities (i.e. functional connectivity).Thus, in the second part, a distributed numerical model based on the resolution of Saint Venant equations coupled to a multi-source erosion module was used to evaluate the respective roles of structural and functional connectivity. Sensitivity analysis of the discretization and parameterization choices (i.e. threshold of contributing drainage area to identify the river network, values of roughness coefficients on hillslopes and the river) showed that the location of the sediment sources in the watershed was more important than the modeling choices when the parameters were limited to realistic range. A general temporal pattern of source contributions was observed. This was consistent with the results of the fingerprinting approach and the distribution of distances from the sources to the river and the outlet. The same pattern persists for different rainfall durations or intensities but became much more variable when bimodal hyetographs or spatially variable precipitation was applied. In addition, the location of the rainfall with respect to the sources determined the average contributions of the sources and thus differences between rainfall events.The two approaches, sediment fingerprinting and numerical modeling, were found to complement each other and their combined application has a high potential for understanding how interactions between structural and functional connectivity control the dynamics of sediment fluxes in mesoscale catchments

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Waterhouse, Emma Kate. "Interactions between coarse sediment transfer, channel change, river engineering and flood risk in an upland gravel-bed river." Thesis, Durham University, 2008. http://etheses.dur.ac.uk/2056/.

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Coarse sediment transfer in upland gravel-bed river systems is often neglected in the design and operation of river management schemes. Yet, it is increasingly attributed to problems within upland environments including bank erosion and enhanced flood risk. Developing a sufficient understanding of coarse sediment transfer and channel change requires strategic field monitoring. Predicting future channel change and flood risk under varying management options requires numerical modelling. This thesis employs a combined field monitoring and numerical modelling approach to explore the relationship between coarse sediment transfer, lateral channel change, river engineering and flood risk. Intensive field monitoring is used to understand sediment transfer and channel change. Methods include repeat cross-sectional resurvey, bank erosion pins and bank-top surveys, and sediment impact sensors. These data are used to illustrate the spatial and temporal variability of in-channel sedimentation and rates and mechanisms of bank erosion. When analysed further, these data explain patterns of sedimentation and demonstrate implications of coarse sediment accumulation for flood risk. The data are then used in the development and application of a quasi two-dimensional model of channel change. The model couples a one-dimensional sediment routing model with a lateral adjustment component to simulate patterns of downstream fining alongside vertical and lateral channel changes. By using a split channel approach, asymmetrical width adjustments are simulated based on critical shear stress thresholds. Lateral differences in bed elevation and curvature are used to distribute shear stress across the channel. Simulations are run to explore scenarios including changing the flow regime, removing bank protection and implementing a river engineering scheme on a reach with high sedimentation and bank erosion problems. The results highlight the potential impact that poor river management can have on upland rivers, demonstrating enhanced bank erosion upstream and greater sedimentation downstream of the engineered reach. The accumulation of sediment results in increased flood risk.

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Perks, Matthew Thomas. "Spatial and temporal dynamics of fine fluvial sediment transfer : implications for monitoring and management of upland river systems." Thesis, Durham University, 2013. http://etheses.dur.ac.uk/7307/.

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Although the impacts of changing land use on the magnitude and timing of erosion in lowland catchments are well documented, much less is known about the transfer dynamics of fine sediment through the upland hydrological networks. Using a novel distributed monitoring approach, this thesis examines the magnitude, timing and physical characteristics of fluvial fine sediment in two adjacent upland rivers in North Yorkshire (UK). Annual suspended sediment yield (SSY) estimates range from 33.92 t km-2 in the 131 km2 Upper Derwent catchment to 57.91 t km-2 in the 96 km2 River Esk catchment. Infrequent events were found to be of greatest importance, transferring up to 38% of the annual load in under two days. Simple annual and seasonal rating curves were constructed and are effective in predicting SSC with relative errors of less than 15%. Analysis of within-storm fine sediment dynamics indicated the dominance of sources proximal to the channel in the Esk catchment, whereas sediment sources in the Upper Derwent were more variable. Distributed time-integrated fine sediment sampling identified high SSYs in the headwaters of the Upper Derwent whereas in the headwaters of the Esk the minimum SSY was found with tributaries draining the central valley having maximum SSYs. Analysis of the absolute particle size observed significant downstream fining in both catchments and strong positive relationships between flow and particle size of the transported sediment. The data collected are also applied to four real-world scenarios to demonstrate the effectiveness of this approach. This research has enhanced our understanding of fine sediment delivery to upland channels through the assessment of the fine sediment dynamics at a range of temporal and spatial scales rarely studied in these environments.

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Taddei, Dorothée. "TRANSFERT DE MATIERE ET D'ENERGIE DANS LES SEDIMENTS D'UN COMPLEXE RECIFAL ANTHROPISE (ÎLE DE LA RÉUNION, OCEAN INDIEN)." Phd thesis, Université de la Réunion, 2006. http://tel.archives-ouvertes.fr/tel-00472730.

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Les récifs coralliens sont des écosystèmes très productifs. Lieu de stockage, transformation, et production de matière, les sédiments pourraient également jouer un rôle dans le fonctionnement du récif. L'objectif était d'évaluer ce rôle dans le transfert de matière et d'énergie du récif de La Saline (île de la Réunion). Trois axes de recherches ont été développés : la caractérisation de la zone via des analyses physicochimiques, l'étude du métabolisme des sédiments (production et statut trophique), et, de la composante biologique, macrofaune et mégafaune (holothuries). Les mesures physicochimiques ont montré un état de perturbation limité, même si localement, des enrichissements par les eaux douces en éléments nutritifs sont bien réels (arrière-récifs de Planch'Alizé et Grand Trou d'Eau). Á l'échelle du récif (9 stations, 2 saisons), les sédiments sont hétérotrophes (production nette = 31.6, respiration R = 109.6, production brute Pg = 77.9 mmolC m-2 j-1 et Pg/R = 0.7). La macrofaune ne constitue pas un groupe important dans le réseau trophique (134 taxons, avec en moyenne, 32.86 individus 0.2 m-2 et 0.059 gPS 0.2m-2). Par comparaison, les biomasses des populations de Holothuria atra et H. leucospilota, atteignent 7.92 gPS m-2. L'hétérogénéité spatiale du métabolisme des stations est en accord avec des caractéristiques physicochimiques du milieu reflétant la double influence océan - terre (enrichissement par eaux douces). Les stations les plus productives et hétérotrophes se situent dans l'arrière-récif où l'influence océanique est minime. La macrofaune est sous l'influence du facteur hydrodynamisme alors que les holothuries se développent dans les zones très productives. Le compartiment sédimentaire joue donc un rôle essentiel de filtre pour la matière organique importée. Ce fonctionnement est influencé par l'hydrodynamisme qui conditionne les pertes de matière et d'énergie. Ces pertes sont limitées par l'action des holothuries (forte densité 3 ind m-2) qui stockent la matière organique sous forme de biomasse, et stimulent probablement la production locale (excrétion et bioturbation). En conclusion, à l'échelle de l'écosystème, les sédiments assurent un recyclage essentiel, fonction renforcée par les holothuries qui limitent les pertes de matière et d'énergie dues à l'hydrodynamisme.

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Patault, Edouard. "Analyse multi-échelle des processus d’érosion hydrique et de transferts sédimentaires en territoire agricole : exemple du bassin versant de la Canche (France)." Thesis, Ecole nationale supérieure Mines-Télécom Lille Douai, 2018. http://www.theses.fr/2018MTLD0003/document.

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L’érosion hydrique est un processus majeur de dégradation des sols dans le monde avec des conséquences multiples : perte de terres agricoles, envasement des cours d’eau, coulées boueuses. En France, la région Hauts-de-France est la zone la plus touchée par ces pertes en terres qui peuvent dépasser les 10 t ha-1 an-1. Si les processus à l’origine de ces transferts sédimentaires ont été largement étudiés par la communauté scientifique ces dernières années, il reste néanmoins des verrous liés aux variabilités spatio-temporelles. De plus, l’efficacité des politiques récentes de lutte contre l’érosion n’est pas quantifiée. Cette étude propose une analyse de la variabilité spatio-temporelle des transferts sédimentaires selon plusieurs échelles (1-1000 km²), et une première évaluation de l’efficacité des politiques d’aménagement au sein d’un bassin du Nord de la France (la Canche ; 1274 km²). Une station de mesure haute-fréquence, a été implémentée à l’exutoire d’un sous-bassin versant de la Canche (la Pommeroye ; 0,54 km²) pour quantifier les transferts hydro-sédimentaires sur deux années hydrologiques contrastées. Selon nos résultats, les transferts varient de 29,4 à 70 t km-2 an-1. 40% du flux est exporté au cours de 3 épisodes érosifs majeurs (sur 48 enregistrés) et les paramètres forçants sont liés à la durée d’un épisode pluvieux et la quantité de précipitations. Sur ce même bassin, la prédiction spatiale à l’échelle centimétrique des transferts hydro-sédimentaires a pu être effectuée via le nouveau modèle d’érosion des sols WATERSED (BRGM) et l’efficacité d’un plan d’aménagement de lutte contre l’érosion a été quantifiée. Nos résultats permettent de valider l’opérabilité du modèle sur ce territoire. Les transferts sédimentaires à l’échelle du parcellaire agricole peuvent atteindre les 76 t km-2 pour un évènement donné et sont influencés par l’état de surface du parcellaire agricole. Une réduction significative (jusqu’à 84%) des transferts par les aménagements d’hydraulique douce est également observée. A l’échelle du bassin de la Canche, l’utilisation de traceurs chimiques et spectrocolorimétriques dans un modèle de mélange (Sed_Sat ; USGS) a permis d’évaluer d’une part les contributions des affluents de la Canche et d’autre part les contributions des sols et des berges (respectivement 30-70%). Des variations spatio-temporelles significatives ont pu être observées et les résultats tendent à montrer un potentiel impact positif des politiques récentes d’aménagement du territoire. Cette étude montre également que de nouveaux traceurs liés à la signature spécifique des particules magnétiques sont particulièrement prometteurs dans ce contexte pour tracer un signal d’érosion des sols. A terme, ces données pourraient être incluses dans des approches sediment fingerprinting. L’analyse selon plusieurs modalités spatio-temporelles et le couplage expérimentation/modélisation améliore donc notre compréhension de la dynamique des transferts sédimentaires sur le bassin versant de la Canche. Cela fournit des résultats essentiels pour orienter les futures politiques de lutte contre l’érosion des sols
Water erosion is a serious concern in global land degradation leading to multiple consequences: loss of arable lands, siltation of streams, mudflows. In France, the Hauts-de-France region is the most affected area, and soil loss can exceed 10 t ha-1 yr-1. Although hydro-sedimentary processes have been widely studied by the scientific community, there is still a lack of knowledge in the understanding of the spatio-temporal variabilities. Additionally, the effectiveness of recent erosion control policies so far cannot be quantified. This study proposes an analysis of the spatio-temporal variability of sedimentary transfer at different scaling (1-1000 km²), and an initial assessment of the effectiveness of management policies within a northern France catchment (the Canche river, 1274 km²). A high-frequency monitoring station was implemented at the outlet of a Canche sub-catchment (the Pommeroye, 0.54 km²) to quantify the hydro-sedimentary transfer over two contrasted hydrologic years. According to our results, sediment yield varies from 29.4 to 70 t km-2 yr-1. 40% of the flux is exported during 3 major erosive events (out of 48 recorded) and the forcing parameters are related to the duration and the amount of rainfall. In this sub-catchment, the centimeter-scale spatial prediction of the hydro-sedimentary transfer was carried out using the new soil erosion model WATERSED (BRGM) and the effectiveness of an anti-erosion management plan was quantified. Our results validate the operability of the model in this context. For a given event, sediment transfer can reach 76 t km-2 yr-1 in agricultural plots and are strongly depending on the soil surface state. A significant reduction (up to 84%) of sedimentary transfer by the anti-erosion plan was also observed. At the scale of the Canche catchment, the use of chemical and spectrocolorimetric tracers in a mixing model (Sed_Sat tool; USGS) evaluated the contributions of the Canche tributaries and sediment sources contributions (i.e. channel banks and soils; 30-70% respectively). Significant spatio-temporal variations have been observed and the results show a potential positive impact of the recent management policies. This study also shows that new tracers related to the specific signature of magnetic particles are promising in the context to trace soil erosion. For further analyses, this data could be included in sediment fingerprinting approaches. Thus, this study based on several spatio-temporal modalities and the coupling of experimentation and modelling improves our understanding of the Canche hydro-sedimentary dynamics. It provides essential results to guide the future erosion control policies

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Shumskykh, Mykyta. "Release of trace elements from contaminated sediments into surface waters during sediments dynamics : an experimental study." Thesis, Tours, 2019. http://www.theses.fr/2019TOUR4008.

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Dans les systèmes aquatiques, la plupart des éléments traces métalliques (ETM) sont piégés dans les sédiments puis peuvent être relargués en fonction des conditions chimiques et de l’activité microbienne à l’interface eau-sédiment. L’objectif de cette étude était d’évaluer l’impact de remise en suspension des sédiments (lors de crues et d’opérations de gestion de barrages) sur la mobilité de certains ETM. Plusieurs conditions expérimentales de lessivage ont été choisies pour simuler ces événements : conditions oxiques et anoxiques sur des sédiments bruts et d’autres irradiés par rayons gamma. L’utilisation d’eau désionisée a permis de maximiser le processus de relargage. Deux types de sédiments, issus de contextes différents, ont été sélectionnés : le barrage de Villerest (France) et la rivière Xiang (Chine). Des expériences à long terme (30 jours) ont permis d’identifier la dégradation de la matière organique, l’activité microbienne et l’altération (voire la dissolution) de phases porteuses d’ETM comme principaux facteurs de contrôle. L’importance de l’activité microbienne n’a pas pu être quantifiée puisque l’irradiation n’a pas stérilisé totalement les sédiments. Enfin, l’impact de tels évènements parait très limité puisque moins de 1% des ETM contenus dans les sédiments ont été libérés
In aquatic systems, most of trace metals (TM) are buried in sediments and then can be released according to chemical conditions and microbial activity occurring at the sediment-water interface. The aim of this study was to assess the impact of resuspension events (flood or maintenance operations for dam reservoir) on the mobility of some TM. Different batch experiment conditions were chosen to mimic those events: under oxic and anoxic conditions on raw sediments and on gamma-irradiated ones (“sterilized” one). The use of deionized water allowed maximizing the release process. Two sediment types issued from different contexts were selected: the Villerest dam reservoir (France) and the Xiang River (China). Long term experiments (30-day long) allowed identifying that organic matter degradation, microbial activity and alteration/dissolution of trace metal bearing phases were the main controlling factors. The gamma-irradiation did not sterilize sediments but only limited aerobic bacteria and enhanced anaerobic activity. The impact of such 24h resuspension event on reservoir waters and downstream biota is very limited as less than 1% of trace elements was released

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Garyfalou, Aikaterini. "Integrated analysis of mass transport deposits : outcrop data, seismic interpretation & fast Fourier transform analysis." Thesis, University of Aberdeen, 2015. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=227755.

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Allison, Alivia Janeil Niemi Tina M. "Paleoenvironmental reconstruction of late Holocene coastal sediments along the southern Dead Sea transform in Aqaba, Jordan." Diss., UMK access, 2007.

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Thesis (M.S.)--Dept. of Geosciences. University of Missouri--Kansas City, 2007.
"A thesis in urban environmental geology." Typescript. Advisor: Tina M. Niemi. Vita. Title from "catalog record" of the print edition Description based on contents viewed Nov. 13, 2007. Includes bibliographical references (leaves 187-195). Online version of the print edition.

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Dissertations / Theses on the topic 'Sediment transfert'

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