Dissertations / Theses: 'Sedimentation'

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Yeoh, Jin Shaun. "Reservoir sedimentation control." Thesis, University of Bristol, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.412359.

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Siyam, Ahmed Musa. "Reservoir sedimentation control." Thesis, University of Bristol, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324265.

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Fonseca, Fonseca Frank Rodolfo. "Sedimentation of oblate ellipsoids." [S.l.] : [s.n.], 2004. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB11244205.

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Paulos, Yonas Kinfu. "Sedimentation between parallel plates." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/30055.

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Settling basins can be shortened by using a stack of horizontal parallel plates which develop boundary layers in which sedimentation can occur. The purpose of this study is to examine the design parameters for such a system and to apply this approach to a fish rearing channel in which settling length is strictly limited. Flow between parallel rough and smooth plates has been modelled together with sediment concentration profile. Accurate description of boundary layer flow requires the solution of Navier-Stokes equations, and due to the complexity of the equations to be solved for turbulent flow some assumptions are made to relate the Reynolds stresses to turbulent kinetic energy and turbulent energy dissipation rate. The simplified equations are solved using a numerical method which uses the approach given by the TEACH code. The flow parameters obtained from the turbulent flow model are used to obtain the sediment concentration profile within the settling plates. Numerical solution of the sedimentation process is obtained by adopting the general transport equation. The lower plate is assumed to retain sediments reaching the bottom. The design of a sedimentation tank for a fish rearing unit with high velocity of flow has been investigated. The effectiveness of the sedimentation tank depends on the uniformity of flow attained at the inlet, and experiments were conducted to obtain the most suitable geometric system to achieve uniform flow distribution without affecting other performances of the fish rearing unit. The main difficulties to overcome were the heavy circulation present in the sedimentation tank and the clogging of the distributing system by suspended particles. Several distributing systems were investigated, the best is discussed in detail. It was concluded that a stack of horizontal parallel plates can be used in fish rearing systems where space is limited for settling sediments. Flow distribution along the vertical at the entrance to the plates determines the efficiency of the sediment settling process and a suitable geometrical configuration can be constructed to distribute the high velocity flow uniformly across the vertical. Numerical modelling of sediment removal ratio for flow between smooth and rough parallel plates has been calculated. The results show that almost the same pattern of sediment deposition occurs for both the smooth-smooth and rough-smooth plate arrangements.
Applied Science, Faculty of
Civil Engineering, Department of
Graduate

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Rothwell, Robin Guy. "Sedimentation on basin plains." Thesis, University of Southampton, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240961.

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Couch, Matthew. "Aggregation, sedimentation and compaction." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260616.

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Dittmers, Klaus Hauke. "Late Weichselian to Holocene sedimentation in the inner Kara Sea : qualification and quantification of processes = Sedimentationsprozesse in der inneren Kara-See (Spät-Weichsel bis Holozän) /." Bremerhaven : Alfred-Wegener-Inst. für Polar- und Meeresforschung, 2006. http://www.gbv.de/dms/goettingen/510037178.pdf.

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Wünsch, Olaf. "Schwingungsinduzierte Sedimentation in viskoplastischen Fluiden." Kassel Univ.-Bibliothek, 2008. http://nbn-resolving.de/urn:nbn:de:hebis:34-2008011419992.

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Campos, RogeÌrio. "Three-dimensional reservoir sedimentation model." Thesis, University of Newcastle Upon Tyne, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.421172.

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Blanchette, François Alain 1978. "Sedimentation in a stratified ambient." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/29986.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mathematics, 2003.
Includes bibliographical references (p. 147-156).
We study the interaction between settling particles and a stratified ambient in a variety of contexts. We first study the generation of large scale fluid motions by the localised release of a finite mass of particles in the form of plumes or gravity currents. We present the results of a combined theoretical and experimental study describing the evolution of particle clouds formed by the release of heavy particles. In the early stages of motion, particle clouds behave as turbulent fluid thermals; however, their radial expansion eventually stops and particles settle from the base of the cloud at their individual settling speed. We focus on deducing a criterion for the various modes of particle deposition from particle clouds in a stratified ambient. We proceed to study the deposition patterns resulting from particle-laden gravity currents that spread horizontally when released in a particle-free ambient. Using a box-model, we focus on bidisperse gravity currents and examine the resulting particle distribution and maximal deposit length. We then turn to suspensions where particles are initially present throughout the fluid. The simultaneous presence of particles and of a stratified ambient may lead to behaviour analogous to double-diffusive systems, with particles playing the role of a diffusing component. We examine the linear stability of the settling of a particle concentration gradient in a stratified fluid. Numerical simulations allow us to determine the stability of the system for a broad range of particle settling speeds and diffusion coefficients. We then report on layering arising from sedimentation in a density stratified ambient beneath an inclined wall.
(cont.) From our experimental study, we describe the series of horizontal intrusions formed by particle-free fluid intruding at its level of neutral buoyancy. We present numerical models describing the time evolution of the concentration of particles and the layer formation. Finally, we present an experimental and theoretical study of the combined influence of hindered settling and settling speed variations due to an ambient stratification. We develop a criterion for the stability of a suspension settling in a stratified ambient and experimental observations allow us to qualify the main features of this instability.
by François Alain Blanchette.
Ph.D.

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Tolouie, Esmaiel. "Reservoir sedimentation and de-siltation." Thesis, University of Birmingham, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.551025.

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An attempt has been made to review and summarize available knowledge pertaining to sedimentation and de-siltation of storage reservoirs. Additional data have been collected on Sefid - Rud Reservoir (Iran), during its normal and de-siltation operation periods. Some supplementary measures have been introduced to increase the de-siltation efficiency of flushing operations, based on field observations and experiments made during de- iltation operation of Sefid - Rud Reservoir. These measures seem to be a practical and cheap tools for conservation and rehabilitation of large - capacity reservoirs. It is hoped that the subject of resevoir sedimentation may be advanced as much as its importance warrants.

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Roberts, Jennifer Carter. "Vegetative Response to Hurricane Sedimentation." ScholarWorks@UNO, 2009. http://scholarworks.uno.edu/td/986.

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This research investigated the response of the dominant salt marsh macrophyte Spartina alterniflora var. Loisel to sedimentation from Hurricanes Gustav and Ike. A range of sedimentation was used to track the above and belowground plant response, as well as the volume of mineral and organic matter, in the upper reaches of the marsh soil from September 2008 to April 2009. Where storm sedimentation was greatest (~3.5 cm), there were significant increases in live aboveground biomass. Although live belowground biomass did not change significantly over time, the volumetric contribution of both mineral and soil organic matter in the shallow marsh soil increased. These results indicate that hurricane sedimentation may benefit subsiding coastal marshes by stimulating aboveground vegetation mass as well as soil organic matter volume. However, these results imply that there may be a sediment thickness threshold that must be met before such positive effects are expressed.

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JUFFROY, CORINNE. "Sedimentation d'une suspension - effet boycott." Paris 7, 1994. http://www.theses.fr/1994PA077323.

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L'objectif de cette etude est de mettre en evidence les consequences de l'effet boycott en rheologie des milieux disperses. Il est possible d'augmenter le rendement du mecanisme de la sedimentation en realisant des dispositifs constitues de recipients a parois inclinees. On a pu ainsi verifier que le processus de sedimentation s'effectuait beaucoup plus rapidement dans une cuve inclinee que dans une cuve verticale dans les memes conditions. En effet, une fraction des particules se depose sur la paroi inferieure du recipient sous l'effet de la gravite et forme ainsi une fine couche de sediment. Simultanement, il apparait le long de la paroi superieure du recipient une couche marginale de fluide anime d'un mouvement de convection ascendant. On observe alors une acceleration du processus de sedimentation. Ce phenomene est connu sous le nom d'effet boycott. Nous avons pu l'observer lors de l'etude de la sedimentation entre deux cylindres coaxiaux en rotation. L'acceleration normale a l'axe du cylindre induit la formation d'une couche de sediment le long de la paroi externe du cylindre et d'une couche marginale de fluide le long de la paroi interne. Nous avons, dans un cadre experimental et theorique, mis en evidence l'effet boycott pour des suspensions concentrees de spheres rigides et de particules susceptibles de floculer. Nous avons ensuite etudie la fluidisation solide-liquide dans une colonne verticale puis dans une colonne inclinee afin de montrer l'analogie existant avec le phenomene de la sedimentation

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Volentik, Alain C. M. "Tephra transport, sedimentation and hazards." [Tampa, Fla] : University of South Florida, 2009. http://purl.fcla.edu/usf/dc/et/SFE0002949.

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Roop, Heidi Anne. "Sedimentation in a proglacial lake : interpreting intra- and inter-annual sedimentation in Linnévatnet, Spitsbergen, Norway /." Connect to online version, 2007. http://ada.mtholyoke.edu/setr/websrc/pdfs/www/2007/235.pdf.

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Undergraduate honors paper--Mount Holyoke College, 2007. Dept. of Earth and Environment.
Includes one CD-Rom appendix of 2005-2006 grain size data. Includes bibliographical references (leaves 125-129).

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Garis, Sargon. "Sedimentation of stormwater from construction activities." Thesis, KTH, Hållbar utveckling, miljövetenskap och teknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-224318.

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Vattenhantering i infrastrukturprojekt är ett viktigt ämne eftersom det kan påverka den omgivande miljön på ett negativt sätt. I projekt med förorenat mark kan vattnet innehålla allt från metaller till polyaromatiska kolväten, vilket medför svårigheter att hantera. Vattenföroreningarna orsakas av utgrävning, grundläggning, injektering, betonggjutning och bergsprängning. Vattnet kan delvis bildas av regnvatten som faller på byggarbetsplatsen eller genom schaktning under grundvattennivån. Det vatten som genom pumpning avleds från en arbetsplats eller uppfodras är känt som länsvatten. Syftet med detta examensarbete är att undersöka hur urvalet och tillämpningen av metoder för länsvatten kan förenklas och optimeras för att passa svenska förhållanden. Vidare är syftet att utvärdera hur informationen om olika tekniker är relaterad till hur entreprenörer arbetar i praktiken under vissa förhållanden. Avhandlingen består av tre delar. Den första delen är en teoretisk beskrivning av svenska lagar och utsläppskrav som gäller för länsvatten, vanliga reningsmetoder som används och hantering av länsvatten i Washington. Den andra delen är en fallstudie med ett studiebesök på byggarbetsplatsen Marieholmförbindelsen. Den tredje delen består av analytiska beräkningar och jämförelser mot provdata. Resultaten visar att vanliga container behållare bör endast användas för sedimentering av sandpartiklar eftersom ytområdet är begränsat vilket ger en kortare sedimenteringstid. De har också en begränsad flödeskapacitet vilket måste tas till hänsyn för att få en effektiv sedimentering. Specifika krav på övervakning och underhåll av container behållare bör finnas för entreprenören. I fall med mindre partiklar som till exempel silt bör användning av container behållare uteslutas, förutom vid användnings som försedimenteringssteg. Resultaten visar även att vid sedimentering av partiklar mindre än medelsilt är det nödvändigt med en uppehållstid på minst 10 timmar. Uppehållstiden kan däremot skilja sig från 10 timmar till allt uppemot 100 timmar för till exempel fin silt, som har en partikelstorlek mellan 0,0063 mm-0,002 mm. För lera skulle detta innebära en uppehållstid på minst 100 timmar vilket motsvarar mer än 4 dagar. Genom att använda traditionell sedimentering som reningsteknik skulle man antingen behöva ett stort sedimentationsområde eller ett mycket lågt flöde. Detta innebär att traditionell sedimentering är orimlig att använda sig av på grund av ekonomiska aspekter, rymdbegränsningar och effektivitet. Baserad på resultat och slutsatser, föreslås följande rekommendationer: •Vanliga container behållare som kräver hög underhållning och övervakning, rekommenderas inte att användas i större utsträckning än som ett försedimenteringssteg för partiklar som är mindre än grovsilt som har en partikeldiameter mellan 0,02-0,063 mm. •Det är viktigt att ha en helhetssyn genom att skapa tydliga riktlinjer för entreprenörerna. •Det är lämpligt att använda den hydrauliska effekten, A, för att säkerställa en korrekt konfiguration och god separationskapacitet.
Water management in infrastructure projects is an important topic since it could affect the surrounding environment in a negative way. In projects with contaminated land, the water could contain everything from metals to polyaromatic hydrocarbons which entails difficulties in managing. The water can be formed partly by rainwater that falls on the construction site or by excavation below the water level. The water pollution is caused by excavation, foundation, grouting, concrete castings and rock blasting. This water is known as stormwater discharges from construction activities. The aim of the thesis is to investigate how the selection and application of methods for stormwater management from construction activities can be simplified and optimized in order to suit Swedish conditions. Further the aim is to evaluate how the information available about different techniques relates to how the contractors work in practice under some conditions. The thesis consists of three parts. The first part theoretical description of Swedish laws and requirements dealing with stormwater discharge from construction activities, common purification methods that are used and management of stormwater discharge in the state Washington. The second part is a case study with a study visit at the construction site of Marieholmförbindelsen. The third part consists of analytical calculations and comparisons to measured data. The results show that regular containers should only be used to sediment sand particles since the surface area is limited which gives a reduced sedimentation time. They also have a limited flow capacity, which must be followed to work properly. The requirement of self-monitoring and maintenance for the contractor should be increased. In other cases, with smaller particles to settle such as silt, regular containers should not be used greater than as a pre-sedimentation step. The results also show that for sedimentation of particles smaller than medium silt it is necessary with a residence time of minimum 10 hours. This means that for the soil type fine silt, which has a particle range between 0.0063mm-0.002mm, the residence time can differs between 10-100 hours. For the soil type clay this would mean a residence time of at least 100 hours which equals more than 4 days. By using traditional sedimentation as purification technique one would either need a huge sedimentation area or a very small flow. Either of these solutions is unreasonable due to economic aspects, space limitations and efficiency. Based on the results and conclusions, the following recommendations can be proposed: •Regular containers demands a high maintenance and self-monitoring, and isn’t recommended to use in greater occurrence than as a pre-sedimentation step for particles smaller than course silt, which has a particle diameter between 0.02-0.063mm. •Use a holistic approach by creating clear guidelines for the contractors. •Use the hydraulic efficiency, λ, to ensure a proper configuration and a good separation capacity.

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Spedding, Nick. "Meltwater controls on ice-marginal sedimentation." Thesis, University of Edinburgh, 1999. http://hdl.handle.net/1842/26959.

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This thesis explores the influence that meltwater exerts on styles of ice-marginal sedimentation, using past and present examples from Iceland. The study glaciers display marked contrasts in form, size and composition of moraines which are unlikely to reflect differences in rates of subglacial erosion. This is because the study glaciers occupy a similar climate, show similar relief, sit above similar bedrock, and are inferred to flow at similar speeds. The observed variation in moraine properties must reflect some other process which intervenes to modify sediment transport relationships prior to the arrival of debris at the ice edge. I argue that this key factor which controls sediment transport - and, as a result, the potential to form moraines - is the behaviour of subglacial meltwater flows. Studies of the sediment load of its outlet river show that Sólheimajökull is a highly erosive glacier, yet the quantity of debris carried by the ice is extremely small. Consequently, present-day moraine formation is extremely limited. This can best be explained as the product of an aggressive subglacial drainage network which captures and evacuates the bulk of debris generated by subglacial erosion. This state of high efficiency subglacial flushing is likely to dominate the sediment budget of many temperate glaciers. Whereas the present-day margin of Sólheimajökull is debris-poor, the present-day margins of Gígjökull and Steinholtsjökull are debris-rich. This debris consists of two major populations: 1) rounded closets set in a sorted coarse sand and gravel matrix, derived from a series of englacial debris bands, and 2) sub-angular clasts in a poorly-sorted matrix, derived from unusually thick sequences of basal ice.

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Reeve, Glen M. D. "Sedimentation And Hydrodynamics of Whitianga Estuary." The University of Waikato, 2008. http://hdl.handle.net/10289/2344.

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Whitianga Estuary is a bayhead barrier type estuary located on the east of the Coromandel Peninsula, North Island, New Zealand. The catchment has undergone many land-use changes since pre-European settlement. In some areas of the catchment land-use has changed from native forest to grasslands to forestry and back to pasture. These changes in catchment land-use all contribute to increased sedimentation into the estuary. Development of the estuary itself has also occurred in recent times. Much growth has been focussed around the estuary due to Whitianga town-ship having a large boating community, and includes a 170 berth marina and wharf situated at the tidal inlet entrance to the estuary. These, and the extensive canal development engineering works can have substantial impacts on the sedimentation regime, and may modify tidal circulation, flushing, and sediment deposition within the estuary. The principle aim of this research is to assess hydrodynamics and sedimentation of the estuary for future management and development purposes, and also to model different scenarios in order to determine the most cost effective, and least obtrusive design for a proposed boat-ramp and approach channel near the marina. To determine sedimentation rates, sediment cores from four locations were collected to depths of 1 m. Coring locations were chosen based on preliminary model run results, selecting areas that appeared to be long-term sediment sinks of a stable nature. Cores were divided into 10 mm sections and prepared for 210Pb dating and heavy metal analysis, to make an assessment of the vertical sedimentation rates. Recent sedimentation rates were found to be as high as 9 mm/yr post-1950s and past sedimentation rates as high as 30 mm/yr pre-1950s. The use of heavy metal analysis for dating proved difficult as the background levels of the conservative elements used to normalise results varied, making the geochemical analysis approach inappropriate. As bathymetry is one of the most important aspects of modelling, a large amount of surveying was undertaken for this study. LiDAR, singlebeam data, and recent rectified aerial photographs were interpreted for the creation of a bathymetric grid file to be used for hydrodynamic modelling of the estuary. The 3DD numerical model was used to determine tidal flows and current velocities. From this initial hydrodynamic model a particle-tracking model was created to determine sediment transport pathways within the estuary. From the initial 20 m model it was then possible to create a number of nested model grids for the purpose of determining the best practice scenario for the creation of a proposed boat ramp and associated approach channel near the harbour entrance. Hydrodynamic results suggest that residual circulation in Whitianga Estuary is nearly in balance, with a low ebb tidal domination present. Particle tracking results suggest that sediment entrained and carried into and within the estuary will accumulate on the intertidal flats. Sediment transport modelling indicates that the impact of a proposed boat-ramp will result in sedimentation of the dredged approach channel due to reductions in residual and tidal velocities.

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Buckland, David Gyula. "Electrokinetic sedimentation of Welland River sediment." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0002/MQ42132.pdf.

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Wortmann, Heid. "Sedimentation and desiccation of gold mines." Pretoria : [s.n.], 2007. http://upetd.up.ac.za/thesis/available/etd-11052007-152710.

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Abubakar, Muhiddin. "Controlled sedimentation of concentrated colloidal suspensions." Thesis, Imperial College London, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.439508.

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Gray, Thomas Edward. "Sedimentation at subaqueous breaks in slope." Thesis, University of East Anglia, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.410044.

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Cronin, Sean Peter. "Quaternary sedimentation in Welsh lacustrine environments." Thesis, Aberystwyth University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321621.

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Taylor, Mark P. "Holocene sedimentation in River Severn catchments." Thesis, Aberystwyth University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337496.

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Amarasinghe, B. M. W. P. K. "Sedimentation behaviour of complex polydisperse suspensions." Thesis, University of Manchester, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293935.

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van, der Vegt Paul. "Glacial systems sedimentation and tunnel valleys." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610766.

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Schuster, Hannah Samantha. "Asphyxiation by sedimentation? : a sponge's perspective." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/377300/.

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Naturally occurring sedimentation is an important habitat-structuring factor. Increased sedimentation through anthropogenic actions can result in adverse effects to organisms and communities. With industrial activities moving further offshore, new habitats and organisms are affected. Particular in the North-East Atlantic, anthropogenic activities including oil and gas exploration and trawling have been recognised as major hazards to organisms that are sensitive to sedimentation. Sessile filter-feeders, such as sponges, provide vital functions to benthic habitats in many ecosystems and are believed to be adversely affected by turbid waters and settling particles. This project aimed to investigate the effects of sedimentation events from natural and anthropogenic sources on three different sponge species from contrasting habitats, Suberites ficus (shallow water, high sedimentation rates), Sycon ciliatum (shallow water, low sedimentation rates) and Phakellia ventilabrum (deep water, low sedimentation rates). The responses of the three species to increased concentrations of sediment were assessed on a physiological and a transcriptional level. Exposure to drill cuttings from oil exploration was investigated in Sycon ciliatum and Phakellia ventilabrum. It was shown that contrary to the expectations, respiration rates of all investigated sponges were not affected by sedimentation. However, on a molecular level the genes of the stress protein heat shock protein (hsp70) and the enzyme nitric oxide synthase (nos) were significantly regulated during exposure to sediment. Surprisingly, the expression pattern of hsp70 and nos was not consistent between the sponge species. Hsp70 transcription did not change in Suberites ficus, it was down-regulated in Sycon ciliatum and up-regulated in Phakellia ventilabrum. The expression of nos was down-regulated in Suberites ficus and up-regulated in Sycon ciliatum and Phakellia ventilabrum. Stress reaction seemed to be specific to each sponge species and might be dependent on the exposure to sedimentation that naturally occurs in their habitat.

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Warrilow, Ian Mark. "Some sedimentation problems in Stokes flow." Thesis, University of Surrey, 1989. http://epubs.surrey.ac.uk/848546/.

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This thesis explores a number of hydrodynamic sedimentation problems in which the fluid motion is governed by the quasi-steady Stokes approximation. In Chapter Two potential-theoretic methods are used to solve the axisymmetric sedimentation problem of a small slowly rotating and translating particle moving through a fluid-filled circular pore of finite length. In such an approach the velocity and pressure fields, governing the fluid motion, are expressed in terms of relevant harmonic functions, a method which is also applicable to linear elasticity. To give the motivation behind the selection of these harmonics and the analytic methods used, Chapter One discusses two electrostatic problems possessing analogous boundary conditions. In both chapters each problem is reduced to the solution of coupled infinite systems of linear equations and solved by truncation to coupled finite sets. The numerical solutions of these equations are then used to compute approximations to the resistive torque and drag experienced by the sedimenting particle. Chapter Three is divided into two parts. Part I treats the application of the method of subareas to some model electrostatic problems. In Part II we utilize the Oseen integral representation of solutions of the Stokes equations to develop a boundary-integral method for the study of further sedimentation problems. The method involves the discretization of the linear integral equations of the first kind, whose unknowns comprise boundary-stress components, using the method of subareas, thus reducing the integral equations to a system of linear equations. Problems solved using this method include the axial translation of a small particle towards a rigid square plate, an investigation of the flow field development for an axially translating small body moving through a hollow and constricted circular cylinder of finite length, the broadside motion of a circular disk through a circular cylinder and an investigation of a curious phenomenon, known as 'overshooting', in the developing axial velocity profile within a finite-length circular cylinder, given certain inlet and outlet velocity profiles.

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Michalková, Monika. "Human influences on floodplain lake sedimentation." Lyon 3, 2010. http://www.theses.fr/2010LYO31027.

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L'érosion latérale du fleuve Sacramento, Californie: les influences humaines et les conséquences sur l'habitat des lônes L'étude est basée sur l'analyse spatiale et temporelle d'un chenal actif et des lônes associées. On a utilisé une série de photographies aériennes (prises en 1942, 1962, 1985 et 1999) représentant plus de 140 km de longueur. Les changements planimétriques ont été analysés longitudinalement (analyse synchronique) et temporellement (analyse diachronique) pour souligner les structures spatiales et leur évolution temporelle. La révitalisation du Haut Rhône et les premiers résultats de la sédimentation dans les lônes : Des travaux de revitalisation sur le Rhône ont été réalisés en Chautagne, en Belley et Brégnier-Cordon. L'étude des formes et des processus permet d'en évaluer la sédimentation. On considère notamment les trois points suivants: i) la définition du nombre de connexions par an (la fréquence de connexion débordante); ii) les mesures des taux de sédimentation; iii) les analyses statistiques des relations et l'analyse intra-bras (caractérisant les fréquences de connexion et définissant l'espérance de vie des bras morts). Les différents groupes ont été définis par des analyses en composantes principales normées (ACPn). Morphodynamic de la sortie du cut-off méandre: l'analyse expérimentale du terrain et d'études en laboratoire Les expérimentations sur l'évolution morphodynamique à l'embouchure aval d'un bras mort connecté par l'aval et pas par l'amont ont été menées sur un modèle physique de méandres recoupés de la Morava, au VUVH à Bratislava. Les fonnes d'écoulement et de dépôt/érosion pour deux géométries contrastées d'embouchure aval ont été observées, mesurées et simulées par modélisation hydrosédimentaire 2D
Lateral Erosion of the Sacramento River, California: Human influences and consequences for floodplain lake habitats This study is based on a spatial and temporal analysis of the active channel and associated flood plain lakes using aerial photographs spanning five decades (1942, 1962, 1985, 1999) over the entire 140 km long reach. Planimetric changes were analysed longitudinally (synchronic analysis) and temporally (diachronic) to highlight the spatial structures and their evolution through time. Revitalisation of Ht. Rhône and First Feedbacks on Revitalised Floodplain Lakes Sedimentation along the Rhône River The revitalisation work on Rhône River has been done on three different localities: Chautagne, Belley and Brégnier-Cordon. The morphologic form as a result of processes become consequently the control factor. Three steps were considered: i) to define the number connexions by year (the frequency of overbank connexion) ; ii) the measurement 1 of the sedimentation rates iii) the statistical analysis of the relationships and inter-lake analysis (the characterise of connexion frequency and to define the life expectancy of floodplain lakes). The diffèrent groups were defined by nPCA analysis. Morphodynamics of the Exit of a Cut-off Meander: Experimental Findings from Field and Labora tory Studies The morphological evolution of the entrances and exits of abandoned river channels govems their hydrological connectivity. The study focusses on flow and sediment dynamics in the exit of a cut-off meander where the downstream entrance Îs still connected to the main channel, but the upstream entrance is closed. Two similar field and laboratory cases were investigated using innovative velocimetry techniques (acoustic Doppler profiling, image analysis). Laboratory experiments were conducted with a mobile-bed physical model of the Morava river (Slovakia). Field measurements were performed in the exit of the Port-Galland cut-offmeander, Ain river (France)

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30

Zimmermann, Marc. "Sedimentation de particules en ecoulement oscillatoire." Université Louis Pasteur (Strasbourg) (1971-2008), 1988. http://www.theses.fr/1988STR13005.

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Etude experimentale basee sur le reperage spatio-temporel des particules par camera video. Etude de l'influence de la frequence des oscillations, de l'inertie et de la forme des particules sur leur ralentissement en ecoulement oscillatoire. Modelisation

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31

Lynch, Edward Douglas Herbolzheimer Eric. "Sedimentation in quiescent and sheared suspensions /." Diss., Pasadena, Calif. : California Institute of Technology, 1985. http://resolver.caltech.edu/CaltechETD:etd-03272008-090808.

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32

George, Matthew William. "Reservoir Sedimentation: The Economics of Sustainability." BYU ScholarsArchive, 2016. https://scholarsarchive.byu.edu/etd/5955.

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Despite mounting demand for a more sustainable worldwide water supply system, available reservoir capacity is relentlessly diminishing due to sedimentation. This fact, coupled with a decrease in the rate of dam construction, indicate an impending water supply dilemma. In the future, dams should be designed following a life cycle management approach rather than the typical short-sighted design life technique.Neither sustainable reservoir lifespans nor intergenerational equity is achieved through conventional cost-benefit analyses (CBA), which render all benefits and costs projected to occur more than several decades into a project as negligible. Consequently, future expenditures, including dam decommissioning or retrofitting with sediment management facilities, are regarded as non-factors in an analysis. CBAs have also historically failed to account for the impacts of sedimentation on infrastructure and the environment over time.Alternatives to the traditional application of the CBA do exist, however. These include dam owners establishing retirement funds or insurance policies, beneficiaries paying for rehabilitation or maintenance, and economists incorporating infrastructure damages and potentially declining discount rates into their analyses.To analyze the disadvantages of not managing sediment, a case study of costs caused from sedimentation impacts at Gavins Point Dam was performed. Impacts from sedimentation at Gavins Point Dam include, among many others, upstream municipal flooding and downstream bank stabilization and sandbar construction. The financial analysis considered the time value of money and showed that the value of expenditures to resolve sedimentation impacts is equivalent to 70% of the original construction cost. Including the costs of additional impacts would amplify this result. Design and operations decisions at Gavins Point Dam could have been drastically different, leading to a more sustainable project, if these expenditures from sedimentation impacts had been included in the initial economic analyses.It is recommended that multidisciplinary discussions occur at multiagency levels to consider changes to traditional CBAs for long-term water supply projects. These discussions should investigate the creation of funding to address sediment management at existing dams. The frequency of bathymetric surveys should also be increased, which would lead to a better understanding of the condition of our infrastructure. By pursuing these recommendations and integrating the aforementioned alternatives to the CBA, economic studies for reservoirs will be more accurate, reservoir lifespans will be more sustainable, profits will be extended indefinitely, and the economic burdens passed to future generations will be lessened.

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Rüther, Nils. "Computational Fluid Dynamics in Fluvial Sedimentation Engineering." Doctoral thesis, Norwegian University of Science and Technology, Department of Hydraulic and Environmental Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1917.

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The present dissertation describes the improvement of a numerical model when predicting sedimentation and erosion processes in fluvial geomorphology. Various algorithms and parameters were implemented in a computational fluid dynamic model for simulation of three-dimensional water flow and coupled sediment transport to gain an insight into the capabilities of the numerical model. Within the scope of the test cases the model simulated suspended load concentrations at a water intake, transient bed deformation in a 90º channel bend, grain sorting processes as well as an unsteady flow regime in a 180º channel bend, transient bed deformation in a sine-shaped meandering channel with occurring bed forms and the free-forming meander evolution of an initially straight channel. All results matched well with the measurements. The results also showed that using computational fluid dynamics for modeling water flow and sediment transport is one step closer of having a universal predictor for processes in fluvial geomorphology. However, there are limitations and some uncertainties in computing the water surface location and alluvial roughness as well as in turbulence modeling. These should be clarified in future investigations.

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Johnson, Hunter Neal. "SEDIMENTATION SOLUTIONS FOR THE PORT OF PASCAGOULA." MSSTATE, 2008. http://sun.library.msstate.edu/ETD-db/theses/available/etd-10222008-123300/.

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The purpose of this work, which is designed for the Port of Pascagoula, is to locate sedimentation problems, identify sediment characteristics, and devise a method to decrease the ports dredging costs. In order to understand what sediment problems are typical of the Port of Pascagoula the characteristics that are associated with sediment transportation in the ports harbors are examined. This examination consists of a field investigation followed by an extensive evaluation of the data. Once the characteristics that are unique to the harbors are identified, potential solutions are examined. These potential solutions are evaluated until a feasible and efficient plan is devised to reduce the ports dependency on dredging. Recommendations include agitation, a fluid mud trap, and the practice of active nautical depth. Each of these solutions would allow the port to reduce its dredge costs.

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Traynor, John-Joe. "Arenig sedimentation and basin evolution in Wales." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306613.

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Thoms, Martin C. "Channel sedimentation within urban gravel bed rivers." Thesis, Loughborough University, 1987. https://dspace.lboro.ac.uk/2134/10844.

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Fine substrate sediments are considered to be important in the management of urban river systems. Urban construction activities have been reported to increase sediment loads causing the temporary siltation of channel substrates within the urban area. Nevertheless fine sediment derived from urban areas frequently carry toxic material well in excess of background concentration levels. While the soluble phase of heavy metals and the importance of their association with suspended sediment has received considerable attention, longer term studies of fine urban river-bed sediments are limited. Furthermore studies of heavy pollutants in active stream sediments, below mine waste tips, have shown the channel substrate can provide a long term store for heavy metals in association with fine sediments. This thesis investigates the variety of impacts that urbanisation has upon the sedimentation of gravel bed rivers. A freeze coring technique and infIltration baskets have been used to study the textural-geochemical properties of fme matrix sediment and its development within an urban river-bed framework, within and below a number of contrasting urban catchments in the U.K. Complex urban hydrological and sedimentological regimes are shown to have a variable influence upon matrix sedimentation. The actual volume of matrix present within the urbanised substrate is influenced by the degree of urbanisation within the catchment. Furthermore this sediment is finer in size and associated heavy metal concentrations are well in excess of natural background levels. Although heavy metal levels do correlate slightly with textural characteristics, the presence of maximum concentrations at depth in the substrate indicate possible mobilisation of metals within the urbanised river-bed. The temporal behaviour of matrix development within an urbanised substrate is shown to differ from natural river-beds. Despite high suspended sediment concentrations the magnitude of the potential rate of supply is lower, by 50 percent, and dominated by organic material. This sediment also contains elevated heavy metal cocnentrations. This contrasts to the inorganic sediment ingress of natural river substrates. It is concluded that fine matrix sediments within urban gravel bed rivers should be at least of concern to public health engineers, water authorities and conservationists.

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Douillet, Guilhem Amin. "Flow and sedimentation of pyroclastic density currents." Diss., Ludwig-Maximilians-Universität München, 2015. http://nbn-resolving.de/urn:nbn:de:bvb:19-182857.

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Oliveira, Luis Otavio Aguiar. "Integrated tectonics and sedimentation in extensional basins." Thesis, Royal Holloway, University of London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340598.

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Shi, Shaozhong. "Observational and theoretical aspects of tsunami sedimentation." Thesis, Coventry University, 1995. http://curve.coventry.ac.uk/open/items/0a4c8219-19e9-a6c2-4417-440b0e84702e/1.

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This dissertation presents the detailed results of investigations into the coastal geomorphological effects and sedimentation processes associated with a recent large tsunami event which took place on the 12th December 1992 in Flores, Indonesia, and the stratigraphical and sedimentological study of a widespread sand layer preserved in coastal sedimentary sequences along the eastern coast of Scotland representing a low-frequency, high-energy marine event, which took place at circa 7,000 radiocarbon years B.P. With modern alalogues, established in this dissertation, of both tsunami and storm surge sedimentary characteristics and sedimentation processes as the key, together with high-resolution sedimentological evidence obtained from the circa 7,000 radiocarbon years B. P. event, competing hypotheses of the likely causes of the marine flooding by either a tsunami or storm surge event are tested. It is concluded that the circa 7,000 B. P. marine flooding event was a tsunami, believed to have been generated by one of the world's largest submarine landslides in the Norwegian Sea - the Second Storegga Slide. The particle size composition of tsunami sediments is found to vary from well sorted to poorly sorted and is controlled by both the characteristics of the source sedement (local coastal sediments) and sedimentation processes associated with tsunami inundation. Tsunami sediments deposited on land are believed to form continuous and discontinuous sedimentary sheets ascending up to levels distinctively higher than contemporary sea levels and to contain a general landward-fining trend and multiple sets of grading (fining-upward) sequences, reflecting spatial changes in particle size composition. A conceptual model of coastal tsunami sedimentation is established including processes of seaward and landward sediment movements, episodic rapid deposition, sediment accumulation and erosion.

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Evans, R. "Fan-delta sedimentation in a Spitsbergen fjord." Thesis, University of East Anglia, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378910.

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Yang, Chane-Yuan. "Simulations of colloidal suspensions sedimentation and stabilization." Thesis, University of Leeds, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.446047.

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Wose, A. E. "Saline intrusion and sedimentation in sea outfalls." Thesis, University of Liverpool, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241444.

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Tabrez, Ali Rashid. "Slope sedimentation around the NW Indian Ocean." Thesis, University of Southampton, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295607.

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Bell, Andrew. "Silurian sedimentation and tectonics in North Wales." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292896.

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Acosta-Cabronero, Julio. "MRI measurements of gravity-driven sedimentation processes." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614237.

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Zarrebini, Mehran. "Sedimentation from particle laden plumes and jets." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621032.

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Post, Riley Aaren. "Determining Lake Sedimentation Rates Using Radionuclide Tracers." Thesis, University of Iowa, 2011. https://ir.uiowa.edu/etd/4898.

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The objective of this study was to determine the origin of sediment currently collected in Black Lake, an extremely productive salmon fishing environment located along a remote section of the Alaska Peninsula, AK. To meet the goals of this project, soil cores were collected at the site during an extensive field study. The field investigation was based on a prior numerical study, which revealed the most erodible areas and the hydrologic patterns in Black Lake and its tributaries, namely the Alec River. From this study, select locations of the catchment were chosen for coring. These included the Alec River Delta, Black Lake, and four tributaries in the catchment. These samples were analyzed for the radionuclides 137Cs and 210Pb to determine soil deposition rates using Gamma Spectroscopy. To determine the sedimentation rate of each coring location, spikes in the 137Cs activity were connected to the known cesium deposition peak in 1964 and the depth of soil above the peak was divided by the number of years that have passed. This gave a spatially averaged deposition rate within the lake of roughly 0.25 cm/y. This result closely compared to the numerical study of Elhakeem and Papanicolaou (2008) and to a study done in close proximity to Black Lake in the early 1990s (Stihler et al. 1992). The rate of each location was then validated by visually analyzing each core using soil color demarcation lines to determine the soil composition. This analysis resulted in the discovery of a variety of soil types ranging from silts and clays, to coarse sands, to volcanic tephra. It was concluded that the lake flow patterns, the introduction of volcanic material from nearby Mt. Veniaminof, and back water resulting from deposition occurring down stream of Black Lake at the Black River's junction with the West Fork River are some of the main contributors for the deposition in the lake.

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Karl, Joanna Robin. "Gravity Sedimentation: A One-Dimensional Numerical Model." PDXScholar, 1993. https://pdxscholar.library.pdx.edu/open_access_etds/4594.

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A large fraction of the current cost of wastewater treatment is from the treatment and disposal of wastewater sludge. Improved design, energy efficiency, and performance of dewatering facilities could significantly decrease transport and disposal costs. Dewatering facilities are designed based on field experience, trial and error, pilot plant testing, and/or full scale testing. Design is generally time-consuming and expensive. A full-scale test typically consists_ of side-by-side operation of 4 to 5 full-scale dewatering units for several weeks to more than 6 months. Theoretical modeling of the physics of dewatering units such as the belt filter press, based on laboratory determined sludge properties, would better predict dewatering performance. This research developed a numerical computer model of the physics of gravity sedimentation. The model simulated the gravity sedimentation portion of the belt filter press. The model was developed from a physically-based numerical computer model of cake filtration by Wells (1990). As opposed to the cake filtration model, the inertial and gravity terms were retained in the gravity sedimentation model. Although in the cake filtration model, the inertial terms were shown to be negligible, according to Dixon, Souter, and Buchanan (1985), inertial effects in gravity sedimentation cannot generally be ignored. The region where inertia is important is the narrow interface between suspension and sediment. In the cake filtration model the gravity term was negligible due to the relatively large magnitude of the applied pressure; but in the gravity sedimentation model, since there was no applied pressure, it was necessary to consider the effect of gravity. _ Two final governing equations were developed - solid continuity and total momentum with continuity ("momentum"). ·The finite difference equations used a "space-staggered" mesh. The solid continuity equation was solved using an explicit formulation, with a forward difference in time and central difference in space. The "momentum" equation used a fully implicit formulation with a forward difference in time. The modeler could choose either a central difference or forward difference in space. Non-linear terms were linearized. Boundary Conditions and constitutive relationships were determined. Numerical errors in the numerical model were analyzed. The model was calibrated to known data and verified with additional data. The model was extremely sensitive to the constitutive relationships used, but relatively unaffected by the At or the use of central difference or forward difference for the spatial derivative term in the "momentum" equation. Correlations of the calibrated model to data with a low initial concentration show that the constitutive parameters approximate the data, but not very well. Model runs with low initial concentration required the addition of artificial viscosity to remain stable. The gravity term was always significant, whereas the inertial terms were many orders of magnitude less than gravity. However, the lower the initial concentration, the larger the inertial terms. In addition to the belt filter press, the model can also be applied to cake filtration and design of gravity sedimentation tanks as well.

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Wittmann, Thorsten. "Zur Analyse der Grenzdynamik von stochastischen Vielteilchensystemen am Beispiel des Pickard-Tory-Sedimentationsmodells." [S.l. : s.n.], 2003. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB10633968.

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Beckham, Richard Edward. "Confocal microscopy study of colloidal sedimentation and crystallization." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2682.

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Dissertations / Theses on the topic 'Sedimentation'

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