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Wiberg, Patricia Louise. "Mechanics of bedload sediment transport /." Thesis, Connect to this title online; UW restricted, 1987. http://hdl.handle.net/1773/10988.
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Weltmer, Micah A. "Bedform evolution and sediment transport under breaking waves." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Mar%5FWeltmer.pdf.
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Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, March 2003.Thesis advisor(s): Timothy P. Stanton, Edward B. Thornton. Includes bibliographical references (p. 79-83). Also available online.
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Wilcock, Peter R. (Peter Richard) 1953. "Bed-load transport of mixed-size sediment." Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/14866.
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Inpasihardjo, Koensatwanto. "Bed load transport of nonuniform size sediment in mountain rivers." Thesis, University of Newcastle Upon Tyne, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316082.
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Schmelter, Mark L. "Applications of Bayesian Statistics in Fluvial Bed Load Transport." DigitalCommons@USU, 2013. http://digitalcommons.usu.edu/etd/1515.
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Fluvial sediment transport is a process that has long been important in managing water resources. While we intuitively recognize that increased flow amounts to increased sediment discharge, there is still significant uncertainty in the details. Because sediment transport---and in the context of this dissertation, bed load transport---is a strongly nonlinear process that is usually modeled using empirical or semi-empirical equations, there exists a large amount of uncertainty around model parameters, predictions, and model suitability. The focus of this dissertation is to develop and demonstrate a series of physically- and statistically-based sediment transport models that build on the scientific knowledge of the physics of sediment transport while evaluating the phenomenon in an environment that leads us to robust estimates of parametric, predictive, and model selection uncertainty. The success of these models permits us to put theoretically and procedurally sound uncertainty estimates to a process that is widely acknowledged to be variable and uncertain but has, to date, not developed robust statistical tools to quantify this uncertainty. This dissertation comprises four individual papers that methodically develop and prove the concept of Bayesian statistical sediment transport models. A simple pedagogical model is developed using synthetic and laboratory flume data---this model is then compared to traditional statistical approaches that are more familiar to the discipline. A single-fraction sediment transport model is developed on the Snake River to develop a probabilistic sediment budget whose results are compared to a sediment budget developed through an ad hoc uncertainty analysis. Lastly, a multi-fraction sediment transport model is developed in which multiple fractions of laboratory flume experiments are modeled and the results are compared to the standard theory that has been already published. The results of these models demonstrate that a Bayesian approach to sediment transport has much to offer the discipline as it is able to 1) accurately provide estimates of model parameters, 2) quantify parametric uncertainty of the models, 3) provide a means to evaluate relative model fit between different deterministic equations, 4) provide predictive uncertainty of sediment transport, 5) propagate uncertainty from the root causes into secondary and tertiary dependent functions, and 6) provide a means by which testing of established theory can be performed.
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Ayyoubzadeh, Seyed Ali. "Hydraulic aspects of straight-compound channel flow and bed load sediment transport." Thesis, University of Birmingham, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391507.
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Figueiredo, Fabíola Tocchini de. "Caracterização do escoamento no limite de mobilização de um leito granular cisalhado por um fluido." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264086.
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Orientadores: Eugênio Spanó Rosa, Erick de Moraes FranklinDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
Made available in DSpace on 2018-08-20T18:21:08Z (GMT). No. of bitstreams: 1 Figueiredo_FabiolaTocchinide_M.pdf: 4897680 bytes, checksum: 594ff391035bd0cca23d8d6ccc9465f2 (MD5) Previous issue date: 2012
Resumo: O transporte de grãos por um fluido em escoamento é frequentemente encontrado na natureza e na indústria. Está presente, por exemplo, na erosão das margens de rios, na migração de dunas no deserto e no transporte de areia em dutos. O mecanismo de transporte se dá através da transferência da quantidade de movimento do fluido para os grãos. Quando a força exercida pelo fluido no leito granular é capaz de mover alguns grãos, mas é relativamente pequena comparada ao peso dos grãos, o escoamento não é capaz de transportar os grãos como suspensão. Forma-se uma camada móvel de grãos em contato com a parte fixa do leito, conhecida como leito móvel (em inglês, 'bed-load'). Se o fluido é um líquido, a espessura desta camada móvel é de apenas alguns diâmetros de grão. A transferência de quantidade de movimento do fluido para os grãos altera o campo de escoamento tornando o perfil de velocidades diferente do caso de leito fixo. Este trabalho está interessado em entender as mudanças que acontecem no escoamento de um líquido turbulento devido à presença de um leito granular móvel, este fenômeno é conhecido como 'feed-back effect'. Os experimentos foram realizados em um canal horizontal de seção retangular e o equipamento de medida PIV (em inglês, 'Particle Image Velocimetry') foi usado para medir o escoamento turbulento de água sobre leitos granulares fixos e móveis. Os perfis de velocidade sobre leito granular fixo e móvel foram medidos para dois diferentes tamanhos de grãos, 160 'mi'm e 360 'mi'm, para a mesma vazão, em condições próximas ao limite de mobilidade dos grãos. Esta é a primeira vez que esta perturbação é experimentalmente medida no caso de escoamento turbulento de líquidos em regime hidraulicamente liso
Abstract: The transport of granular matter by a fluid flow is frequently found in nature and in industry. It is present for example, in the erosion of river banks, in the displacement of desert dunes and on the transport of sand in hydrocarbon pipelines. The entraining mechanism is the momentum transfer from the fluid flow to the grains. When the forces exerted by the fluid flow on the granular bed are able to move some grains, but are relatively small compared to the grains weight, the flow is not able to transport grains as a suspension. Instead a mobile layer of grains, known as bed-load, takes place. If the fluid is a liquid, the bed-load thickness is only a few grains diameters. The momentum transfer from the fluid to the mobile layer alters the fluid flow itself, i. e., the fluid flow is different from that if the bed were static. In this work we are interested in quantifying the changes (perturbation) caused by a mobile layer of grains (granular transport as bed-load) on a turbulent liquid flow. The experiments were performed on a horizontal closed-conduit channel of rectangular cross section and a PIV (Particle Image Velocimetry) device was used to measure the turbulent water flow over fixed and mobile granular beds. The turbulent fully-developed velocity profiles over fixed and mobile granular beds were measured for two different diameter of grains, 160 'mi'm and 360 'mi'm, for roughly the same water flow rates, in conditions near the threshold of the bed-load. The spatial resolution of the measurements allows the experimental quantification of this perturbation and comparison with bed-load theories. The mean flow profiles were obtained, so that the effects of bed-load on the shear stress could be determined. This is the first time that this perturbation is experimentally measured in the case of turbulent flows of liquids
Mestrado
Termica e Fluidos
Mestra em Engenharia Mecânica
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Santos, Bruno José Oliveira. "Coherent structures in open channel flows with bed load transport over an hydraulically rough bed." Master's thesis, Faculdade de Ciências e Tecnologia, 2013. http://hdl.handle.net/10362/11204.
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Dissertação para obtenção do Grau de Mestre em
Engenharia Civil – Perfil de EstruturasThe degradation of forests through the impacts of devastating wildfires increase unprotected soils area which consequently favours soil erosion processes. The sediment production is continuously reaching water courses in these areas which may result in important impacts in the flow morphodynamics and hydrodynamics. Sediment overfeeding induces important changes in the turbulent structure of the flow, mainly in momentum fluxes and exchange of momentum and mass between different layers in the flow structure, consequently affecting its ecological features. Coherent structures play an important role on sediment transport and mixing processes which are important in the fluxes that govern the turbulent structure. This study is aimed at evaluating the impacts of sediment transport on flow hydrodynamics, namely on the statistics characterizing coherent movements. In order to accomplish the purposed objective, experimental tests were undertook in laboratorial environment where two-dimensional instantaneous flow velocity fields in both directions, streamwise and vertical, were measured through means of Particle Image Velocimetry (PIV) technique. Two laboratory tests were simulated, consisting on a framework gravel bed with sand matrix and a framework gravel bed with sediment transport imposed at near capacity conditions. For both tests, the quadrant threshold analysis technique was employed and shear stress distribution statistics were analysed and discussed in what concerns their contribution and persistence. The results show that, in the near bed region, mobile bed conditions make sweep events assume a major role in the shear stress production processes. Also, larger events become less frequent in the pythmenic region, comparing with the immobile bed results. The impacts of mobile sediment in the near bed region over the flow structure are analysed and discussed in detail through probability density function distributions, in dimensional and non-dimensional data.
Fundação para a Ciência e Tecnologia - PTDC/ECM/099752/2008 ; undo de Europeu de Desenvolvimento Económico e Regional(FEDER) através do Programa Operacional Factores de Competitividade(COMPETE)FCOMP 01 0124 FEDER 009735
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Shaw, Susan Calder. "Bedload transport of mixed-sized sediments by wind /." Thesis, Connect to this title online; UW restricted, 1994. http://hdl.handle.net/1773/6742.
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Ngusaru, Amani S. "Cross-shore migration of lunate megaripples and bedload sediment transport models /." Internet access available to MUN users only, 2000. http://collections.mun.ca/u?/theses,37433.
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Pulcuoglu, Basar. "Comparative Study On Sediment Transport Equations For Delta Formations In Reservoirs." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/2/12610577/index.pdf.
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In this study, a qualitative and comparative investigation on sediment transport equations used in prediction of rserevoir sedimentation is presented. 32 sediment transport equations, which are selected by literature review on sand and gravel size ranges, grouped according to the median particle sizes on which their derivation based. In order to compare these equations computer program DELTA, which is a one dimensional simulation program developed by Graf and Altinakar (1998) for the prediction of delta formation in resrvoirs, is used. Computer simulation is performed within each group of sediment transport equations in order to determine the most suitable equation for corresponding median diameter of sediment particles. 8 of the equations gave simulation results that are in good agreement with average values related to delta deposition extent, height and location in the reservoir. The effects of river slope change and median diameter change on delta deposition also investigated and simulation results are compared with previous model studies.
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Mekonnen, Muluneh Admass. "Modeling flow and sediment transport in water bodies and watersheds." Doctoral thesis, KTH, Vattendragsteknik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4703.
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The research focus is on the various modeling aspects of flow and sediment transport in water bodies and watersheds. The interaction of flow with a mobile bed involves a complex process in which various turbulent scales characterized by coherent structures cause a chaotic sediment motion. In many rivers and natural waterways secondary flows that are dominating flow struc-tures bring about more complications. In estuaries and open waterbodies thermal stratification and internal mixing control the flow structure besides the flow interaction with the mobile bed. To adequately model these processes 3D coupled flow and transport models are needed. The research is based on use and adaptation of open source codes for 3D hydrodynamic and sediment transport model known as Estuarine Coastal Ocean Model (ECOMSED) and the Soil and Water Assessment Tool (SWAT) model. A bed load transport model was developed and coupled to ECOMSED. The flow and sediment transport characteristics in a curved channel and a river reach were successfully captured by the model. Improvements in ECOMSED were made to study the effect of wind and basin bathymetry on mixing and flow exchange between two estuaries. Using spectral analysis the hydrological component of SWAT model was investigated for its applicability under limited data conditions in three Ethiopian catchments.QC 20100827
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Wilbers, Antoine. "The development and hydraulic roughness of subaqueous dunes /." Utrecht : Koninklijk Nederlands Aardrijkskundig Genootschap, 2004. http://www.loc.gov/catdir/toc/fy0708/2004464077.html.
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Ipson, Mark K. "Analysis of the Sediment Transport Capabilities of FESWMS FST2DH." Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1542.pdf.
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Admass, Muluneh. "3-D numerical modeling of flow and sediment transport in rivers." Licentiate thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-323.
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Cecchetto, M. "The development of stochastic based transport models to predict the advection and diffusion of bed-load sediment." Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/17584/.
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Many morphological and environmental problems in rivers are associated with the transport of sediment, in particular with the movement of material along the stream bed. The complex nature of turbulent flow and the variability inherent within granular beds, along with the mutual influence one plays on the other, can only be described using the concepts of probability. It follows that the intermittent motion of bed-load particles can be termed by random variables. The stochasticity of key variables has been recently identified as a source of diffusion, i.e. suggesting that a plume of bed-load grains tends to spread while moving in the main flow direction. In this study the application of a Lagrangian analysis to existing high-frequency measurements of moving natural gravel particles contained in a tracking database helped to identify and scale the diffusive regimes related to different stages of grains' motion. Lagrangian tracking data allowed for an in-depth, study of the stochasticity of the particle step length, i.e. the single longitudinal distance computed by a grain from the entrainment to the deposition. The information on the distributed step lengths is then incorporated into a modified version of the Exner mass balance equation which has been developed to model the experimental advective and diffusive transport observed in long duration flume experiments with graded bed deposits comprised of natural sand and crashed marble gravel that have been previously reported. The modelling results indicate that the relative size of bed roughness, together with the thickness of the mixing surficial layer of the bed, play a major role in dictating the pattern of behaviour of particle motion. As the time-dependent burial depth of grains influences the vertical mixing and therefore the downstream diffusion of particles, concentrating the research only on the surficial motion of particles appears restrictive. In order to attain an insight view of the bed and to overcome the previous experimental limitations in terms of the description of the particle step distribution, a non-intrusive technique has been implemented in an annular flume to track the time history of tracing grains subject to intermittent motion in a bed made of transparent glass beads. In the light of the new information on particle transport, a more general Exner-based model incorporates the idea that tracer particles arriving at position x at time t started their random hops r at many different times. Its application to the latest sediment tracer concentration data has proven to be promising in that convincing detailed descriptions of the observed advective and diffusive behaviour of bed-load transport were obtained.
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Brummer, Christopher Jon. "Influence of mass wasting on bed-surface armoring, lag formation, and sediment storage in mountain drainage basins of western Washington State /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/6738.
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Cope, Michael James. "How the Choice of Bed Material Load Equations and Flow Duration Curves Impacts Estimates of Effective Discharge." BYU ScholarsArchive, 2017. https://scholarsarchive.byu.edu/etd/6378.
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The purpose of this study is to analyze how estimates of an important geomorphic parameter, effective discharge, are impacted by the choice of bed material load equations and flow duration curves (FDCs). The Yang (1979), Brownlie (1981), and Pagosa equations developed by Rosgen (2006) were compared for predicting bed material load. To calculate the bed material load using the Pagosa equations, the bedload and suspended load are calculated separately and the results are added together. To compare the effectiveness of the equations, measured bed material load data from the USGS Open-File Report 89-67 were used. Following the calculations, the equation results were compared to the measured data. It was determined that the Pagosa equations performed the best overall, followed by Brownlie and then Yang. The superior performance of the Pagosa equations is likely due to the equations being calibrated. USGS regression equations for FDCs were compared to a method developed by Dr. David Rosgen in which a dimensionless FDC (DFDC) is developed. Weminuche Creek in southwestern Colorado was used as the study site. Rosgen's DFDC method requires the selection of a streamgage for a stream that exhibits the same hydro-physiographic characteristics as the site of interest. An FDC is developed for the gaged site and made dimensionless by dividing the discharges by the bankfull discharge of the gaged site. The DFDC is then made dimensional by multiplying by the bankfull discharge of the site of interest and the resulting dimensional FDC is taken as the FDC of the ungaged site. The USGS regression equations underpredicted the discharges while Rosgen's DFDC method overpredicted them. Rosgen's DFDC method produced more accurate results than the USGS regression equations for Weminuche Creek. To calculate the effective discharge, the FDC was used to develop a flow frequency curve which was then multiplied by the sediment rating curve. Effective discharge calculations were performed for Weminuche Creek using several combinations of bed material load prediction equations and FDCs. The USGS regression equations, Rosgen's DFDC method, and streamgage data were all used in conjunction with the Yang and Pagosa equations. The Brownlie equation predicted zero bed material load for Weminuche Creek, and was thus not used to calculate the effective discharge. When the USGS regression equations were used with the Yang and Pagosa equations, the calculated effective discharge was approximately 4.5 cms for both bed material load prediction equations. When Rosgen's DFDC method and streamgage data were used with the Yang and Pagosa equations, the effective discharge was approximately 13.5 cms. From these results, it was determined that the bed material load prediction equations had little impact on the effective discharge for Weminuche Creek while the FDCs did influence the results.
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Liu, Xin. "Numerical Modelling of Shallow Water Flows over Mobile Beds." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/35131.
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This Ph.D. thesis aims to develop numerical models for two-dimensional and three-dimensional shallow water systems over mobile beds. In order to accomplish the goal of this dissertation, the following sub-projects are defined and completed.
1: The first sub-project consists in developing a robust two-dimensional coupled numerical model based on an unstructured mesh, which can simulate rapidly varying flows over an erodible bed involving wet–dry fronts that is a complex yet practically important problem. In this task, the central-upwind scheme is extended to simulation of bed erosion and sediment transport, a modified shallow water system is adopted to improve the model, a wetting and drying scheme is proposed for tracking wet-dry interfaces and stably predict the bed erosion near wet-dry area. The shallow water, sediment transport and bed evolution equations are coupled in the governing system. The proposed model can efficiently track wetting and drying interfaces while preserving stability in simulating the bed erosion near the wet-dry fronts. The additional terms in shallow water equations can improve the accuracy of the simulation when intense sediment-exchange exists; the central-upwind method adopted in the current study shows great accuracy and efficiency compared with other popular solvers; the developed model is robust, efficient and accurate in dealing with various challenging cases.
2: The second sub-project consists in developing a novel numerical scheme for a coupled two-dimensional hyperbolic system consisting of the shallow water equations with friction terms coupled with the equations modeling the sediment transport and bed evolution. The resulting 5*5 hyperbolic system of balance laws is numerically solved using a Godunov-type central-upwind scheme on a triangular grid. A spatially second-order and temporally third-order central-upwind scheme has been derived to discretize the conservative hyperbolic sub-system. However, such schemes need a correct evaluation of local wave speeds to avoid instabilities. To address such an issue, a mathematical result by the Lagrange theorem is used in the proposed scheme. Consequently, a computationally expensive process of finding all of the eigenvalues of the Jacobian matrices is avoided: The upper/lower bounds on the largest/smallest local speeds of propagation are estimated using the Lagrange theorem. In addition, a special discretization of the bed-slope term is proposed to guarantee the well-balanced property of the designed scheme.
3: The third sub-project consists in designing a novel scheme to estimate bed-load fluxes which can produce more accurate results than the previously reported coupled model. Using a pair of local wave speeds different from those used for the flow, a novel wave estimator in conjunction with the central upwind method is proposed and successfully applied to the coupled water-sediment system involving a rapid bed-erosion process. It was demonstrated that, in comparison with the decoupled model, applying the proposed novel scheme to approximate the bed-load fluxes can successfully avoid the numerical oscillations caused by simple and less stable schemes, e.g. simple upwind methods; in comparison with the coupled model using same flux-estimator for both hydrodynamic and morphological systems, the proposed numerical scheme successfully prevents excessive numerical diffusion for prediction of bed evolution. Consequently, the proposed scheme has advantages in terms of accuracy which are shown in several numerical tests. In addition, analytical expressions have been provided for calculating the eigenvalues of the coupled shallow-water-Exner system, which greatly enhances the efficiency of the proposed method.
4: The fourth sub-project consists in developing a three-dimensional numerical model for the simulation of unsteady non-hydrostatic shallow water flows on unstructured grids using the finite volume method. The free surface variations are modeled by a characteristics-based scheme which simulates sub- and super-critical flows. Three-dimensional velocity components are considered in a collocated arrangement with a sigma coordinate system. A special treatment of the pressure term is developed to avoid the water surface oscillations. Convective and diffusive terms are approximated explicitly, and an implicit discretization is used for the pressure term. The unstructured grid in the horizontal direction and the sigma coordinate in the vertical direction facilitate the use of the model in complicated geometries.
5: The fifth sub-project consists in developing a well-balanced three-dimensional shallow water model which is able to simulate shock waves over dry bed. Due to the hydrostatic simplification of the vertical momentum equation, the governing system of equations is not hyperbolic and can not be solved using standard hyperbolic solvers. That is, one can not use a high-order Godunov-type scheme to compute all fluxes through cell-interfaces. This may cause the model to fail in simulations of some unsteady-flows with discontinuities, e.g., dam-break flows and floods. To overcome this difficulty, a novel numerical scheme for the three-dimensional shallow water equations is proposed using a relaxation approach in order to convert the system to a hyperbolic one. Thus, a high-order Godunov-type central-upwind scheme based on the finite volume method can be applied to approximate the numerical fluxes. The proposed model can also preserve the ``lake at rest'' state and positivity of water depth over irregular bottom topographies based on special reconstruction of the corresponding parameters.
6: The sixth sub-project consists in extending the result of the fifth sub-project to development of a three-dimensional numerical model for shallow water flows over mobile beds, which is able to simulate morphological evolutions under shock waves, e.g. dam-break flows. The hydrodynamic model solves the three-dimensional shallow water equations using a finite volume method on prismatic cells in sigma coordinates based on the scheme prposed in sub-project 5. The morphodynamic model solves an Exner equation consisting of bed-load sediment transportation. The performance of the proposed model has been demonstrated by several laboratory experiments of dam-break flows over mobile beds.
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Schnick, Lori H. "Using a geographic information system (GIS) and the water erosion prediction project model (WEPP) to obtain soil erodibility parameters for predicting sediment yields from urbanizing sub-basins in Montgomery County, Maryland, U.S.A." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 1.59 Mb., 90 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:1430750.
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Gharbi, Mohamed. "Etudes des crues et du transport sédimentaire associé - Application au bassin versant de la Medjerda." Thesis, Toulouse, INPT, 2016. http://www.theses.fr/2016INPT0008/document.
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En Tunisie, les problèmes des inondations et du transport sédimentaire se posent de façon critique, en particulier au niveau du bassin versant de la Medjerda. En effet, depuis la mise en service du barrage de Sidi Salem (1981) sur le bassin de la Medjerda, des modifications du régime d’écoulement en aval sont apparues sous la forme d’une diminution de la débitance. Cette diminution a eu pour conséquence d’abaisser la capacité de l’Oued à transporter les sédiments et de favoriser leur dépôt. Ceci a provoqué un engraissement du lit, et par conséquent, une occurrence accrue des inondations. Le recours à la modélisation numérique s’avère nécessaire pour mieux comprendre ce risque. Une première partie de ce travail se rapporte à une étude expérimentale menée au niveau d’une installation expérimentale de l’Institut National Agronomique de Tunisie (INAT). L’objectif est de visualiser l’évolution morphologique du fond d’un canal constitué de sable fin sous l’effet d’un écoulement permanent à faible pente. Des simulations numériques ont été effectuées avec différentes lois de transport solide par charriage sur des données expérimentales. L’objectif est de vérifier l’applicabilité de ces lois pour la prédiction de la capacité du transport solide par charriage. Des tests de l’effet du diamètre des matériaux sur la variation du taux de sédiments transportés ont été réalisés. Enfin, des simulations avec différentes formules disponibles sous SISYPHE couplé avec TELEMAC 2D ont été effectuées, pour prédire l’évolution de la couche de sable fin dans le canal. Dans une seconde partie, des simulations de la Medjerda avec des modèles hydrauliques 1D et 2D ont été réalisées. Ces simulations ont concerné les crues récentes pour lesquelles des données sont disponibles, en particulier la crue spectaculaire de janvier 2003, et la crue la plus récente survenue en février 2012. Dans un premier temps, des simulations numériques 1D ont été réalisées via les deux logiciels MIKE 11 et HEC RAS afin de contrôler le comportement de la ligne d’eau lors de ces crues. Dans un second temps, des modélisations hydrauliques bidimensionnelles 2D via le code TELEMAC 2D ont été effectuées ; le but était de déterminer l’étendue de la crue et d’identifier les zones sensibles à l’inondation. La dernière partie de ce travail porte sur l’étude du transport sédimentaire au niveau de la Medjerda. Dans un premier temps, une modélisation unidimensionnelle (1D) du transport solide total lors de la crue de 2003 le long de la moyenne vallée de la Medjerda. Une analyse de l’influence des quantités de matériaux transportés lors des crues sur l’évolution géomorphologique de la Medjerda a été faite. Dans un second temps, une modélisation bidimensionnelle (2D) du transport solide a été réalisée en utilisant SISYPHE couplé avec TELEMAC 2D. Enfin, une nouvelle approche de calcul du transport sédimentaire par charriage, basée sur le modèle d’érosion-déposition de Charru, (2006) a été testée. À l’issue de ce travail, une étude comparative entre les différents résultats obtenus, pour vérifier la validité de ces approches pour le cas de la Medjerda, a été effectuéeIn Tunisia, the problem of floods and sediment transport is critically arising, especially in the Medjerda watershed. Since the construction of Sidi Salem dam, there is a remarkable morphological change, especially on the downstream side. We note a gradual enhancement of the river bed in the downstream direction and therefore, increased occurrence of floods. So, the use of numerical modeling is needed to better understand this risk. An experimental study carried out in a rectangular inclinable flume at the National Institute of Agronomy of Tunisia (INAT). The aim is to visualize the morphological evolution of the channel bottom consisting of fine sand under permanent flow. In the first part, a comparative analysis was conducted between bed load transport rates models with experimental data, in order to test and validate the new bed load model proposed by Lajeunesse et al. (2010), then to check the grain size effect on the sediment transport capacity. After that, we are interested in the study of the morphological evolution in rivers. It was performed through numerical modeling using SISYPHE coupled with TELEMAC 2D. The aim is to analyze the morphological changes in the channel bottom. In the second part, several simulations have been conducted between 1D and 2D hydraulic models. These simulations concerned the recent floods for which data are available, especially the flood in January 2003 and the latest floods occurred in February 2012. Initially, a 1D hydraulic model using the MIKE 11 and HEC RAS software was performed in order to control the behavior of the water line profile during these floods. Secondly, a twodimensional hydraulic model was conducted using the code TELEMAC 2D in order to determine flood extent and to identify flood sensitive areas. The last part of this work will focus on the study of sediment transport at the Medjerda. Initially, we conducted a one-dimensional modeling (1D) of the total sediment transport along the middle valley of the Medjerda river. An analysis of the influence of the amounts of the materials transported by the Medjerda during flood was performed to determine their effects on the river morphological evolution. Secondly, a two-dimensional modeling was performed (2D) of sediment transport using the code SISYPHE coupled with TELEMAC 2D was also performed. We became interested in the study of sediment transport by thrusting only, to see the effect of this transport mode to the morphological evolution. In addition, we opted for a new approach to calculation of bed load sediment transport model based on the erosion -deposition Charru (2006). At the end of this work, a comparative study between the different results to see the validity of this new approach to the case of Medjerda was considered
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Johnson, Charley R. "Migration of Dredged Material Mounds: Predictions Based on Field Measurements of Waves, Currents, and Suspended Sediments, Brunswick, GA." Thesis, Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-04082005-145658/unrestricted/johnson%5Fcharley%5Fr%5F200505%5Fmast.pdf.
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Thesis (M. S.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2005.F. Michael Saunders, Ph.D., Committee Member ; Kevin Haas, Ph.D., Committee Member ; Paul A. Work, Ph.D., Committee Chair. Includes bibliographical references.
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Ashiq, Mohammad. "Bed load transport models for coarse bed material rivers." Thesis, University of Newcastle Upon Tyne, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336301.
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Arthur, Scott. "Near bed solids transport in combined sewers." Thesis, University of Abertay Dundee, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309761.
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Meigh, J. R. "Transport of bed material in a gravel-bed river." Thesis, University of East Anglia, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382828.
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O'Neil, Sean. "THREE DIMENSIONAL MOBILE BED DYNAMICS FOR SEDIMENT TRANSPORT MODELING." The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1032548958.
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Li, Qiang. "Numerical simulation of non-equilibrium graded sediment transport." Thesis, University of Glasgow, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320622.
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Clayton, Jordan Arthur. "Sediment transport and channel form in gravel-bed river meanders." Diss., Connect to online resource, 2005. http://wwwlib.umi.com/dissertations/fullcit/3178363.
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Wolcott, John Fredric. "Flume studies of gravel bed surface response to flowing water." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/31033.
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Almost all sediment transport equations incorporate the Shields parameter, which is a ratio of the total boundary shear stress as a driving force and the particle weight as a resisting force. Shields (1936) equated particle resistance to entrainment with particle weight, which is proportional to particle diameter, or bed texture. The present work analyses the particle resistance term in the Shields parameter.
As the bed material adjusts to a given flow condition, bed stability increases. The arrangement of particles into more stable configurations is here termed geometric structure, and includes the formation of pebble clusters, and imbrication. After an initial surface coarsening, here termed textural structure, particle resistance to movement is a function primarily of geometric structure. The Shields number for entrainment is thus a measure of particle resistance due to both types of bed structure rather than the conventional notion of particle resistance due to particle weight.
The response of a mobile bed surface composed of < 8 mm diameter gravels to flowing water was explored in a 6 meter by 0.5 meter flume using four different slopes and various water depths. Corrected bed shear stresses varied between 0.05 and 2.79 Pa. Step increases in discharge with a constant slope caused the bed surface to develop a structure which was more stable at the end of a run than at the beginning. Under these conditions, the Shields number for incipient motion was found to vary between 0.001 and 0.066. This variability can be explained by the degree of geometric structure present. Previous studies, including Shields' work (1936), have implicitly included the effects of geometric structure on incipient motion.
Surface coarsening develops with very low flows, but subsequent coarsening in higher flows is minor, with less than 5% increase in median diameter following a 50% increase in bed shear stress. Calculations of Manning's n based on depth, slope, and velocity measurements show an increase in flow resistance as structure develops. The development of a coarse surface layer appears to be limited by flow characteristics near the bed which are in turn modified by the development of structure. Measurements of the area occupied by the largest stones show that they do not cover more than 14% of the surface during maximum coarsening. Froude scaling of the flume data indicates that the time necessary for development of maximum strength is on the order of a month for natural rivers under steady flow conditions. This suggests that gravel river beds are rarely in equilibrium with natural flow conditions.Arts, Faculty of
Geography, Department of
Graduate
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Teakle, Ian Alan Lester. "Coastal boundary layer and sediment transport modelling /." [St. Lucia, Qld.], 2006. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe19317.pdf.
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Hinton, Darren D. "Complexity of Bed-Load Transport in Gravel Bed Streams: Data Collection, Prediction, and Analysis." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3384.
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Bedload transport has long been known for its complexity. Despite decades of research, significant gaps of understanding exist in the ability to assess and predict bedload movement. This work introduces a comprehensive bedload database that is a compilation of field samples collected over the past 40 years; compares prediction formulae using a subset of the database; evaluates the influence of the armor layer on stream response to sediment input based on a hypothesis linked to one of the tested formulae, presents a mathematically manipulation of the empirical Pagosa Good/Fair formula for bedload transport into a format similar to the semi-empirical Parker Surface-Based 1990 formula; and addresses the complications of bedload transport by collecting bedload samples on a stream in Central Utah. A comprehensive review of available bedload data resulted in a publicly available database with more than 8,000 individual bedload samples on gravel bed streams. Each measurement included extensive and detailed information regarding channel, site, and hydraulic characteristics. A subset of this database was used to compare four calibrated (a single calibration point of a measured bedload transport rate near bankfull discharge is used to improve formula prediction accuracy) and two un-calibrated bedload prediction formulae. The four calibrated formulae include three semi-empirical (a theoretical treatment adjusted to fit bedload measurements) formulae and one empirical (solely based on regression of bedload measurements) formula; the two un-calibrated formulae are both semi-empirical. Of the formulae compared, the empirical Pagosa Good/Fair formula (a calibrated formula) provided the most accurate prediction results with an overall root mean square error of 6.4%, an improvement of several orders of magnitude over the un-calibrated formulae. The Pagosa Good/Fair formula is cast in a form similar to the Parker 1990 formula, suggesting that criticisms stating that the empirical Pagosa method lacks a theoretical basis are unfounded. The hypothesis of equal mobility that states the gradation of the average annual gravel bedload yield for a given stream matches the particle size distribution of the subsurface material is evaluated with relation to the armor layer. Equal mobility is found to correlate to armor layer such that lower armor ratios indicate a greater tendency to uphold the equal mobility hypothesis and increasing armor ratio values tending to move toward supply limited conditions. This correlation provides an upper limit for lightly armored streams. Bedload sampling efforts described in this work compare the Helley-Smith sampler with the net trap sampler and duplicate previous observations that bedload transport collected using net traps increase more rapidly with discharge than for data collected using Helley-Smith samplers. An alternative, relatively low-cost method for collecting bedload during relatively high discharges on highly urbanized streams is also proposed.
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Shim, Jaeho, and Jaeho Shim. "Experimental and Numerical Studies of Grain Scaled Bed-Load Transport." Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/623162.
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Accurately calculating bed load transport rate has been a challenge in hydraulic engineering for decades. Bed load transport depends on the interaction between flow and sediment particles. Analyzing the characteristic of sediment particles motion and determining the velocity of sediment particles on a river bed is essential to quantify the transport rate. Therefore, this dissertation reports on the methods and results of a three-phased investigation to analyze the bed-load transport at the grain scale. The first research phase focused on the experimental study of bed-load transport using particle motion tracking. A series of experiments were conducted in a flume to study bed-load transport. The motion of bed-load particles was captured by a series of images taken by a high-speed camera. A novel particle motion tracking method was developed to automatically detect all the moving particles and calculate the instantaneous particle velocities. The instantaneous bed load transport rate was calculated based on particle velocity and the volume of moving particles. To verify this method, bed load transport rate based on the image processing technique was compared to the manually measured ones as well as data from other experiments. Results showed that the new technique made it possible to quantify the spatial and temporal variations of bed load transport rate at the individual particle scale. The second research study focused on the theoretical study of bed load particle velocity and its distribution. A theoretical equation was derived for calculating the particle velocity and distribution at the equilibrium transport state. It was found the mean particle velocity is a function of average bed shear stress, and the instantaneous velocity of a bed load particle is dependent on the instantaneous bed-shear stress. The PDFs of particle velocity and bed shear stress both vary with the turbulence intensity. Results showed that the newly derived theoretical equation accurately predicted the average particle velocity. The PDF of particle velocity is a log-normal function at high Reynolds number, while it is close to an exponential distribution at low Reynolds number. The third research study focused on the numerical investigation of bed-load transport at the grain scale. In detail, this study was carried out mainly on sediment transport around a bridge pier. Bridge scour is commonly calculated based on the steady flow assumption. In practice, the peak discharge of a 100-year event is used for calculating the bridge scour depth. This will overestimate the scour depth, especially in arid and semi-arid region where the typical storms are high-peak and short duration flash floods. Therefore, the numerical test for simulating sediment transport around a bridge pier in unsteady condition was conducted by using the Smooth Particle Hydrodynamics (SPH) model. The simulation obtained by the DualSPHysics showed the scour process around bride pier in dam break flow. The results showed the local scour depth is affected by the large sediment load accompanying the dam break flow. The maximum scour depth was reached quickly, but only lasted for a few seconds before being back-filled by sediment. The maximum scour depth occurring under unsteady flow is much smaller than the calculated value using peak-flow discharge. In other words, using the peak-flow discharge for designing can overestimate the maximum scour depth in comparison to the actual conditions under a flash flood or any unsteady hydrograph.
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Yeganeh-Bakhtiary, Abbas. "Computational mechanics of bed-load transport at high bottom shear." Kyoto University, 1999. http://hdl.handle.net/2433/181776.
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Tait, Simon Joseph. "The physical processes of bed armouring in mixed grain sediment transport." Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources, 1993. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=59561.
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Yuill, Brendan Thomas. "Sediment Transport and Bed Mobility in a Low-ordered Ephemeral Watershed." Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/195269.
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This dissertation reports the results of a field based study examining sediment transport and bed mobility in a low-ordered, ephemeral watershed. Runoff and sediment transport concentrations were sampled at the watershed outlet to determine flow discharge and sediment flux during approximately 21 flow events, from 1998 - 2007. Sediment collected in flow was measured for grain-size distribution to determine if specific grain-size fractions behave differently while in transport. The coarse sediment yield was measured for mass and grain-size distribution at the watershed outlet for two years, 2005 - 2006. Further, the arrangement and composition of the channel bed material was comprehensively mapped using terrestrial-based photogrammetry for the years, 2005 - 2006. Results show that patterns of sediment transport are complex, controlled in part by flow hydraulics but also by other phenomena. Some of the variation in sediment transport is determined by grain-size. Grain-sizes with different sources within the watershed and that transported by different transport modes were observed to follow different patterns of transport. Also, the channel bed, which serves as the source for the coarse fraction of the sediment transport, was observed to change in grain composition during periods of flow. This tendency for the bed material to evolve in time likely affected the amount and composition of the sediment grains that were entrained from it.An additional objective of this dissertation was to determine how unique the observed patterns of sediment transport were to low-order ephemeral channels. Sediment transport and yield were modeled using bed load transport formulae designed to capture the physical mechanics of transport as observed in perennial streams. Results show that contemporary transport models predict transport within the field site with similar accuracy as that in many perennial systems but not well enough to rely on their predictions for many engineering applications.
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Wang, Le. "Bedload sediment transport and bed evolution in steady and unsteady flows." Thesis, Heriot-Watt University, 2016. http://hdl.handle.net/10399/3099.
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Until recently, bedload sediment transport has generally been investigated under steady flow conditions, which does not represent the typical sediment transport scenarios observed within natural fluvial channels. These channels often experience significant variations in bedload transport and bed morphological evolution under unsteady flow conditions, especially during flood hydrograph events. At present, however, there is a distinct lack of understanding of the interaction between hydrograph flow properties and the variability in bedload transport and bed evolution. Within the current study, different series of parametric experiments were conducted in two glass-walled, tilting flume facilities with the main aim of investigating the response of uniform and graded sediment beds to a range of different unsteady flow hydrograph conditions, and compare this to the corresponding response under equivalent steady flow conditions. The novelty of this research against previous studies is highlighted in terms of (i) the identification of the individual influence of hydrograph-related parameters (shape , unsteadiness HG and total water work Wk) on unsteady sediment transport characteristics (e.g. hysteresis and temporal lag) and the resulting bed evolution; (ii) the use of natural-shaped hydrographs (single and double peak) rather than stepped, triangular or trapezoidal hydrographs; (iii) the direct comparison between bedload sediment transport yields and corresponding bed evolution under unsteady hydrograph and equivalent (volume) steady flows; and (iv) enhanced understanding of influence of intergranular effects (e.g. particle exposure and/or hiding) on observed bedload sediment transport behaviour in unsteady and equivalent steady flows. Experiments conducted with both uniform (course sand, d = 1.95mm) and graded (fine gravel, d50 = 2.64mm, 5.00mm) beds not only confirm the clockwise and counter-clockwise hysteresis in measured bed load transport rates, but also reveal no/mixed hysteresis patterns as a transitional condition between these clockwise and counter-clockwise hystereses for bedload transport measured under unsteady flow hydrographs. For graded sediment transport, the intergranular effect on temporal lag and hysteresis patterns for transport of classified fine, medium and coarse size classes within graded (unimodal, bimodal and fine-grained) sediment beds in unsteady flow hydrographs is also revealed. Specifically, the coarse size class tends to respond preferentially to the changing flow and exhibits clockwise hysteresis in general; whereas the fine size class tends to become more active later and demonstrates reduced clockwise, no/mixed or counter-clockwise hysteresis. Corresponding temporal variations and hysteresis patterns in the median db50 size of the bedload transport load are also observed, with the db50 value generally reaching its peaking value during the rising hydrograph limb and indicating a clockwise hysteresis over the hydrograph duration. Bedforms (i.e. dunes and alternate bars) are found to develop only within uniform sediment bed (d = 1.95mm) under both steady and unsteady flows tested. A relevant analysis of the formative conditions under which these bedforms develop is presented. By contrast, no bedforms are observed to form within graded sediment beds; only slight bed evolution (e.g. bed aggradation up to +5mm at upstream) is identified for fine-grained sediment bed (d50 = 2.64mm) runs. Additionally, the median size of the bed surface ds50 is shown to coarsen during the antecedent flow conditions within all graded sediment beds (compared to d50 in specified particle size distributions). This surface coarsening persists over the duration of both steady and unsteady flow events tested in current study [e.g. run-averaged ds50 values: (i) unimodal grading, ds50 = 6.51mm (> d50 = 5mm); (ii) bimodal grading, ds50 = 6.74mm (> d50 = 5mm); and (iii) fine-grained grading, ds50 = 3.62mm (> d50 = 2.64mm)]. The temporal variations in the median bedload size db50 (< ds50 throughout) for both the steady and unsteady flow runs, are also responsible for explaining the development and persistence of the surface armour layer. Bedload transport and bed evolution for uniform and graded sediment beds under steady flows are measured to provide a benchmark for direct comparison with equivalent bedload rates and yields, bedform development, and variations in bedload and bed surface grain size composition under unsteady flows. The difference in effects of unsteady and steady flow is found to be significant for bedload rate (with the unsteady-steady bedload ratio Kq = 0.23 – 14.95), bedload yields (i.e. yield ratio us = 1.11 – 13.56), bedforms (i.e. dunes, alternate bars and etc.) and bedload composition (i.e. db50 ratio Kb = 0.38 – 1.56), but less significant for bed surface composition (i.e. ds50 ratio Ks = 0.92 – 1.33). Further, the individual influence of hydrograph related parameters (shape , unsteadiness HG, total water work Wk) on bedload yields, yield distribution over the rising and falling two limbs of single-peaked hydrographs, and on of bedform characteristics (i.e. type, dimensions) is also evaluated. In more complex flow hydrographs, such as double-peaked hydrographs, the equivalent bedload transport and bed evolution characteristics are also derived. Finally, the presence of specific grain size classes within the graded sediment beds and their influence on the transport of other six classes is considered from comparison of sediment transport characteristics for (i) the unimodal and bimodal sediment mixtures (with the same d50 = 5.0mm), and (ii) the uniform (d = 1.95mm) and fine-grained sediment mixture (d50 = 2.64mm), which arise from relative grain exposure and sheltering effects under the same steady and unsteady flow events. An idealised, theoretical analysis of the hydrodynamic forces and moments associated with these potential impacts is provided. Most importantly, the transport of fine particles is found to vary depending upon the presence state of coarser particle sizes in the surface layer (i.e. stationary or mobile to varying rates), which reveals the mechanism for selective fractional transport within the graded sediment bed under equivalent steady and unsteady hydrograph flow conditions.
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Ashworth, Philip John. "Bedload transport and channel change in gravel-bed rivers." Thesis, University of Stirling, 1987. http://hdl.handle.net/1893/2555.
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Spatial and temporal variations in channel morphology, near-bed velocity, shear stress, bedload transport rate, pebble tracer movement, and bedload and bed material size distribution were measured in seven different channel patterns in two gravel-bed rivers in the Scottish Highlands (the Dubhaig and Feshie) and a proglacial stream in Norway (the Lyngsdalselva). The results showed that there were discernible links between the channel processes and changes which were consistent for all river types. 169 shear stress estimates from velocity profiles with changing discharge showed that Keller's (1971) velocity-reversal hypothesis holds true in different channel patterns of gravel-bed rivers and can be extended to include subunits of the pool/riffle cycle. At discharges near bankfull there is a decrease in the flow strength and amount of bedload movement from the poolhead down to the pooltail (and then riffle). On a broader scale 72 Helley-Smith bedload samples and the movement of over 3700 pebble tracers showed that the entrainment of different size fractions from heterogeneous bed material is inefficient and is overpredicted by the traditional bedload transport equations. Empirical analyses showed that when the armour is mobile/broken large and small particles have almost equal mobility as first proposed by Parker et al. (1982) and Andrews (1983). However for the majority of flow conditions the armour is static and entrainment is selective to a greater or lesser degree depending on the availability of appropriate-sized sediment at the surface and from bank erosion. The magnitude and direction of flow strength and bedload transport helps to explain the location and mode of channel development as revealed by repeated levelling and mapping. The accelerating convergent/decelerating divergent cells of flow alter the channel morphology in predictable ways. The positions of these cells can change with increasing discharge as the channel becomes generally, rather than locally, competent to move coarse sediment. The rates of bank erosion and volumetric scour and fill decreased from the active multi-braided system through to the stable straight channel type.
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Rosier, Burkhard. "Interaction of side weir overflow with bed-load transport and bed morphology in a channel /." Lausanne : EPFL, 2007. http://library.epfl.ch/theses/?nr=3872.
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Thèse Ecole polytechnique fédérale de Lausanne EPFL, no 3872 (2007), Faculté de l'environnement naturel, architectural et construit ENAC, Programme doctoral Environnement, Institut des infrastructures, des ressources et de l'environnement ICARE (Laboratoire de constructions hydrauliques LCH). Dir.: Anton Schleiss.
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Sohag, Mumtaz. "Sediment tracing, bed structure and morphological approaches to sediment transport estimates in a gravel-bed river : the River South Tyne, Northumberland, UK." Thesis, University of Newcastle Upon Tyne, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358970.
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Argast, Timothy. "Advancements in measuring bed load transport with a magnetic detection system." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/42232.
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A large number of bed load measuring devices have been developed in order to estimate sediment transport in rivers. In spite of that, the geomorphic and engineering communities do not have a reliable method to estimate bed material load. Available techniques suffer from insufficient temporal and spatial resolution to capture the variability inherent in bed load movement. This work involves the design and construction of an in situ magnetic detection device, which shows promise as a method capable of overcoming these limitations. The sensors work by inducing a magnetic dipole in naturally magnetic stones via magnets installed in the bed of the channel. These stones then pass over a coil of wire, inducing a small voltage, which is recorded. The system is installed in a five meter flume and is calibrated using video based particle tracking as well as manual sediment collection and sieving. Initial results indicate the new design performs significantly better than its predecessor.
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Mooneyham, Christian David. "Interaction of Clay Wash Load With Gravel Beds." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/84547.
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This study focuses on the interaction of wash load particles with gravel bed rivers. The effects of excess fine sediment loading to streams on general water quality, contaminant transport, and benthic organism mortality has been well examined. A fundamental assumption in fluvial geomorphology and river engineering is that wash load particles ($d<63mu m$) do not deposit to stream beds, but are instead transported downstream until they deposit in reservoirs or estuaries. The goal of this study is to determine if wash load sized particles can deposit to gravel beds, where within the bed substrate deposition occurs, under what hydraulic conditions it occurs, and how the composition of the bed affects the spatial and temporal deposition pattern. Further, this study attempts to quantify the mass flux of wash load to the bed based on a simple mass conservation model using the aforementioned conditions as model parameters. This was accomplished through a series of experiments in which a mixture of pure kaolinite clay was allowed to deposit at constant shear over an acrylic, gravel, or sand-gravel mixture. Discharge was then increased to determine the effects of increased bed shear stress on deposited material and further wash load interaction with the bed.
Results indicate that wash load will deposit to acrylic, gravel, and sand-gravel beds during conditions where no bedload movement is occurring. Bed composition is the primary factor controlling the mass flux of wash load from the water column to the bed. Deposition on acrylic beds forms clay ripples which translate downstream, while deposition in porous beds occurs primarily within the bed substrate. Shear stress also affects mass flux and the magnitude of its effects are related to the bed composition. Discharge increases below the threshold of bedload movement only cause large scale entrainment of deposited particles over non-porous beds. Periods of higher discharge over porous beds result in continued deposition within the bed substrates.
This research enhances not only our knowledge of sediment processes within fluvial systems, but also allows for the quantification of the wash load portion of those processes given minimal initial condition information. The model developed here may be used within larger hydrologic models when examining contaminant spills or mass loading of stream networks with wash load to estimate the mass deposition to the bed. Instances where wash load is contaminated the mass of contaminated sediment retained by the bed is of great importance to local communities given a reliance of residents on that water source for water, livelihood, and recreation.Master of Science
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Pu, Jaan H. "Velocity Profile and Turbulence Structure Measurement Corrections for Sediment Transport-Induced Water-Worked Bed." MDPI, 2021. http://hdl.handle.net/10454/18465.
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YesWhen using point measurement for environmental or sediment laden flows, there is well-recognised risk for not having aligned measurements that causes misinterpretation of the measured velocity data. In reality, these kinds of mismeasurement mainly happen due to the misinterpretation of bed orientation caused by the complexity of its determination in natural flows, especially in bedload laden or rough bed flows. This study proposes a novel bed realignment method to improve the measured data benchmarking by three-dimensional (3D) bed profile orientation and implemented it into different sets of experimental data. More specifically, the effects of realignment on velocity profile and streamwise turbulence structure measurements were investigated. The proposed technique was tested against experimental data collected over a water-worked and an experimentally arranged well-packed beds. Different from the well-packed rough bed, the water-worked bed has been generated after long sediment transport and settling and hence can be used to verify the proposed bed-alignment technique thoroughly. During the flow analysis, the corrected velocity, turbulence intensity and Reynolds stress profiles were compared to the theoretical logarithmic law, exponential law and linear gravity (universal Reynolds stress distribution) profiles, respectively. It has been observed that the proposed method has improved the agreement of the measured velocity and turbulence structure data with their actual theoretical profiles, particularly in the near-bed region (where the ratio of the flow measurement vertical distance to the total water depth, z/h, is limited to ≤0.4).
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Perret, Emeline. "Transport of moderately sorted gravels at low bed shear stress : impact of bed arrangement and fine sediment infiltration." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1223/document.
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Le but de cette thèse est de comprendre la dynamique des graviers au sein des rivières alpines à faible contrainte en utilisant des expériences en laboratoire. Ces rivières sont souvent composées d’une large gamme de sédiments, allant des argiles aux galets. Ces différentes classes sédimentaires peuvent interagir entre elles, ce qui peut rendre difficile l’estimation du transport solide. Des expériences en laboratoire ont été conduites en écoulements instationnaires dans un canal de 18m de long et 1m de large. Deux types de lits ont été étudiés : lits unimodaux et bimodaux. Une attention particulière a été portée sur la réalisation des lits de graviers dans notre canal. Ils ont été créés dans le but d’approcher au mieux la configuration des lits de rivières alpines, c’est-à-dire avec différents arrangements et degrés de colmatage du lit par des sédiments fins. Les lits unimodaux sont composés de graviers peu triés avec divers arrangements de surface. Les lits bimodaux sont composés d’une matrice de graviers peu triés dans laquelle des sédiments fins se sont infiltrés (sables ou limons). Les processus régissant le transport de graviers ont été mis en avant. Le transport de graviers est impacté par l’arrangement du lit, la concentration de sédiments fins dans la couche de charriage, et par le changement de propriétés du lit due à la présence de sédiments fins (cohésion, perméabilité du lit). Plus le lit est arrangé, plus le transport est difficile. Plus la couche de charriage est concentrée en sédiments fins, plus le transport est facile. La forme des sédiments fins est aussi un facteur important pouvant modifier le transport des graviers. La présence de sédiments fins cohésifs dans la matrice peut considérablement réduire le taux de graviers transportés. Un modèle conceptuel a été développé pour résumer les différents processus contrôlant le transport de graviers. Il décrit le comportement des graviers dans les différentes configurations étudiées. L’outil proposé peut aider à comprendre, estimer et interpréter le transport de graviers. Il a été appliqué et discuté sur un cas de terrain sur la rivière de l’Arc. Basé sur ce modèle, nous avons proposé une nouvelle analyse dimensionnelle pour la construction d’un modèle de prédiction de transport solide prenant en compte des paramètres décrivant l’arrangement du lit, les propriétés géotechniques du lit et la présence de sédiments finsThis PhD thesis aims to understand gravel dynamics in Alpine rivers at low bed shear stress using laboratory experiments. Alpine river beds are often poorly sorted and composed of sediments ranging from clay to pebble. To understand interactions between these classes is an issue for predicting bedload rate. Laboratory experiments were performed in a 18m long and 1m wide flume, under unsteady flows. Two types of bed were investigated: unimodal and bimodal beds. A particular attention was paid to the bed construction, which was conducted in order to obtain a nature-like bed 12with different bed arrangements and degrees of clogging. Unimodal beds were made of moderately sorted gravels with different bed surface arrangements. Bimodal beds were made of moderately sorted gravels in which fine sediments (sand or silt) were infiltrated. Gravel rate was found to be impacted by the bed arrangement degree, the fine sediment concentration within the bedload layer and the changes in bed properties due to fine sediment presence (bed cohesion, bed permeability). The more packed the bed is; the more difficult it is to move gravels. The more concentrated in fine sediment the bedload layer is; the easier the transport of gravels is. The shape of fine sediments can also be an important factor for modifying the gravel rate. The presence of cohesive fine sediments within the bed matrix reduces significantly the gravel rate. A conceptual model was developed to recap the different processes controlling gravel transport. It provides a phenomenological description of the overall bed responses to a hydrograph. This tool is designed to help understanding, estimating or interpreting gravel transport in Alpine rivers. The conceptual model was discussed and applied to a field case made on the Arc River. Using the model, we also suggest a new dimensionless analysis for the construction of a bedload predicting model involving parameters describing bed arrangement, bed properties and fine sediment presence
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Hughes, Zoe Joanne. "Small-scale changes in bed morphology and sediment transport under waves and currents." Thesis, University of Southampton, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274473.
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Lane, Stuart Nicholas. "Monitoring and modelling morphology, flow and sediment transport in a gravel-bed stream." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336765.
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Kim, Baeck Oon. "Modeling storm-induced sediment transport on the inner shelf: Effects of bed microstratigraphy." W&M ScholarWorks, 1996. https://scholarworks.wm.edu/etd/1539616714.
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Sediment transport during a storm event on the inner continental shelf was detailed through the development of models based on field experiments conducted at Duck, North Carolina in October 1994. A vertical one-dimensional model (1DV model) was developed by coupling the Grant and Madsen (1986) model with bed stratigraphy to consider real seabeds. Sediment was divided into seven size classes and fractional transport was estimated. Mixing depth and total depth from a simplified sediment conservation equation provided the basis for changing bottom sediment, sediment availability for transport, and armoring processes. These processes involve a feedback between hydrodynamics and bed stratigraphy. A horizontal one-dimensional, depth-resolved model (1DH model) was developed to predict inner-shelf morphological changes. Flow and shear stress fields were calculated using a simple wave transformation model combined with the Jenter and Madsen (1989) model. Sediment flux was computed in relation to fractional transport and armoring processes. The sediment conservation equation was numerically solved to yield bed elevation changes associated with individual size classes. Predictions of suspended sediment concentrations from both models were adjusted by the resuspension coefficient &\gamma\sb0&, resulting in &\gamma\sb0& = 0.001 for the 1DV model and &\gamma\sb0& = 0.002 for the IDH model, respectively. The coupling in the 1DV model was critical to predicting suspended sediment concentrations. Hydrodynamic variables, however, were not significantly affected by changing bottom sediment. Predicted suspended sediment concentrations were higher during the waning phase of the storm than during the erosional phase. Modeled bed stratigraphy showed fining upward sequences. Wind-driven processes on the inner shelf were interpreted using the 1DH model. The magnitude and the direction of horizontal sediment flux were explained in terms of wind-driven currents. Waves produced a sigmoidal-shaped vertical concentration distribution, explaining horizontal gradients of suspended sediment concentrations. The steepness of the sediment flux gradient due to the waves was correlated with wave height. Synchronization of currents and waves was necessary for large flux divergence and morphological changes. During downwelling currents, deposition occurred on the shoreface whereas upwelling currents were accompanied by shoreface/inner shelf erosion. The inner shelf thus responded as either the sink of sediment or the source of sediment.
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Creed, Margaret Julia. "Numerical modelling of sediment transport, bed morphology and porous obstructions in shallow channels." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/28715.
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Many environmental free surface flows involve water and sediment transport. The net changes to the surface level of an erodible bed by sediment entrainment and deposition processes have a feedback effect on the local ow hydrodynamics. Bed morphological change is of great socio-economic and environmental importance in that it affects navigation, flood risk management, water quality, species diversity, and overall river sustainability. This thesis describes a mathematical model of the depth-averaged shallow water-sediment equations based on mass and momentum conservation laws. A 2D numerical model is then presented of the fully coupled, variable-density governing equations, which are solved using a Godunov-type HLLC scheme. Dependent variables are specially selected in the numerical model to handle the presence of the variable-density mixture in the mathematical formulation. The model includes suspended sediment, bedload transport, and bed morphological change. The numerical model is verified against benchmark analytical and semi-analytical solutions for complicated, clear water flows, bedload transport and suspended sediment transport. The well-balanced property of the governing equations is verified for a variable-density dam break flow over a bed step. Simulations of an idealised dam-break flow over an erodible bed, in excellent agreement with previously published results, validate the ability of the model to capture complex water-sediment interactions under rapidly-varying flow conditions and a mobile bed, and validate the eigenstructure of the system of variable-density governing equations. The model is then further validated against laboratory based data for complex 2D partial dam breaks over fixed and mobile beds, respectively. The simulations of 2D dam break flows over mobile beds highlight the sensitivity of the results to the choice of closure relationships for sediment transport. To investigate this further, a parameter study is carried out using a variety of commonly used empirical formulae for suspended sediment transport. The numerical model is also used to inform a theoretical model that predicts the flow through and around a porous obstruction in a shallow channel. This problem is relevant to several practical applications, including flow through aquatic vegetation and the performance of arrays of tidal turbines in a finite-width tidal channel. The theoretical model is used to reinterpret the core flow velocities in laboratory-based data for an array of emergent cylinders in a shallow channel. Comparison with experimental data indicates the maximum obstacle resistance for which the theoretical model is valid. In a final application, the theoretical model examines the optimum arrangement of tidal turbines to generate power in a tidal channel, confirming that natural bed resistance increases the power extraction potential for a partial tidal fence.
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Brown, Anthony Alan. "The self-regulation of a gravel river bed subject to upstream sediment supply." Thesis, University of Aberdeen, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287564.
Full textAbstract:
The aims of this work are to improve the understanding of the way in which a river system approaches equilibrium during and after sediment transporting events and by using experimental data and hypothetical models to gain an insight into mixed grain sized transport and its connection with local bed morphology. Large scale flume experiments were undertaken in a trapezoidal channel where a mixed grain sized river bed is subjected to a variety of imposed sediment loads. The river system was allowed to adjust naturally to the imposed conditions while flow and bed conditions were frequently monitored. Changes to both flow and bed occur at many scales and the superimposition of these changes adds to the complexity of the interpretation of hydraulic and bed data. Three experiments are reported in which the sediment influx differ. One in which no material is added. One in which a feed rate is established equal in magnitude to 50% of the initial transport rate for the equivalent non-fed case. In the third experiment the feed rate is doubled to 100% of the initial transport rate in the degradation experiment. The imposed load is continued for approximately 75% of the duration of the run or until a dynamic equilibrium transport rate is evident within the reach. The river channel is analysed at two distinct scales; grain scale and reach scale. Conclusions about the relative influence of grain and form effects are drawn on the basis of detailed surface texture information and reach scale measurements of the bed surface. A hypothetical model is proposed to show that the transport activity during a degradation experiment can be qualitatively linked to a wave like translation of grain dislodgement through the channel.
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Wittenberg, Lea. "Structural patterns and bed stability of humid temperate, Mediterranean and semi-arid gravel bed rivers." Thesis, University of Newcastle Upon Tyne, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391270.
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Ahmad, Tameez. "Prediction of grain size composition of the armour coat in alluvial bed channels." Thesis, University of Newcastle Upon Tyne, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360275.
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