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departmentresearch group programmeprojectcoordinates)uuid:f6b1db4a8b9b4798bcb686b46dbe82fcDhttp://resolver.tudelft.nl/uuid:f6b1db4a8b9b4798bcb686b46dbe82fc`Developments in the management of flood defences and hydraulic infrastructure in the Netherlands{Jonkman, S.N. (TU Delft Hydraulic Structures and Flood Risk; Ministry of Infrastructure and the Environment); Voortman, H.G. (TU Delft Hydraulic Structures and Flood Risk; Arcadis); Klerk, W.J. (TU Delft Hydraulic Structures and Flood Risk; Deltares); van Vuren, B.G. (TU Delft Hydraulic Structures and Flood Risk; Ministry of Infrastructure and the Environment; HKV Consultants)!This article highlights recent developments in flood risk management in the Netherlands and presents approaches for reliability analysis and asset management for flood defences and hydraulic infrastructure. The functioning of this infrastructure is of great importance for the country as large parts of it are prone to flooding. Based on a nationwide flood risk assessment, new safety standards for flood defences have been derived in the form of maximal acceptable failure probabilities. A framework for the reliabilitybased analysis of the performance of hydraulic infrastructure is introduced. Within this context, various challenges are discussed, such as the dynamic nature of loads, resistance and reliability requirements over time. Various case studies are presented to highlight advances and challenges in various application fields. The first case illustrates how structural health monitoring contributes to a better characterisation of the reliability of the defences and how innovative measures can enhance the reliability. The second case discusses how the river system can be managed in the context of the new safety standards. The third case shows how upgrades and reinforcements of hydraulic structures can be evaluated taking into account (uncertain) future developments, such as sea level rise.oasset management; dikes; flood defences; Flood risk; hydraulic structures; reliability; risk management; riversenjournal article#Hydraulic Structures and Flood Risk)uuid:de9b3e6aaf954af58be20dd1088fd1f7Dhttp://resolver.tudelft.nl/uuid:de9b3e6aaf954af58be20dd1088fd1f7\Potential contribution of hydro power plants to the energy consumption of East Asian islands@Hoes, O.A.C.; Meijer, L.J.J.; Sarfianto, D.R.; Van der Ent, R.J.Population growth, increasing energy demand and depleting fossil fuel reseives put a pressure on conventional methods of electricity generation. Hydropower is an alternative energy source that is known to have a large capacity potential. However, previous estimations of the potential capacity have been inconsistent and incomplete. In this study we identified all locations on East Asian islands (from Japan, Taiwan Phillipines to Indonesia) which are suitable for hydropower. For this we combined USGS's HydroSHEDS elevation data with Global Runoff data from the Global Runoff Data Centre. Such large spatially data gives especially unique information which was not available before. We computed that the total gross hydropower capacity potential is about 2885 TWh per year. Large hydropower accounts for over 27% of this potential, around 39% by small plants, 28% by mini hydropower plants, while micro hydropower only accounts for 6 % of the total potential capacity. Overall this study provides spatially detailed global data that allows both a quick comparison of hydropower potential between regions as well as detailed information on specific hydropower locations, which is especially unique new information for micro hydropower.)runoff; hydropower plants; energy; riversconference paper8Institute of lowland and marine Research Saga University!Civil Engineering and GeosciencesWater Management)uuid:f12389ee9ae94c7ebb99a27da0449f6fDhttp://resolver.tudelft.nl/uui< d:f12389ee9ae94c7ebb99a27da0449f6fNClassifying sediments on Dutch riverbeds using multibeam echosounder systemsEleftherakis, D.Simons, D.G. (promotor)@The economic importance of the Dutch rivers is very high as they are heavily used for inland waterway transport between the Netherlands and their neighbouring countries. A minimum depth must be guaranteed to keep the rivers navigable but also to ensure that the ships can carry maximum cargo. An attractive system for obtaining information about the riverbed bathymetry is the multibeam echosounder (MBES). Furthermore, the MBES received echoes due to acoustic backscatter from the sediments in theory also allow for discriminating between different sediments. The aim of the research presented in this thesis was to develop methods for discriminating between different river sediments using MBES measurements. In order to fulfil this aim, MBES surveys were performed in the Rhine river and the Meuse river between 2007 and 2010. The research shows that indeed the MBES system can be used for discriminating between the different sediments present in the river areas. In addition an important finding is that areas differing in sediment type require different classification approaches.,classification; sediments; rivers; multibeamdoctoral thesisAerospace EngineeringAir Transport and Operations)uuid:118445fc66964fe2abae53272b80db43Dhttp://resolver.tudelft.nl/uuid:118445fc66964fe2abae53272b80db43An intercomparison of sediment classification methods based on multibeam echosounder backscatter and sediment natural radioactivity dataNSnellen, M.; Eleftherakis, S.; AmiriSimkooei, A.; Koomans, R.L.; Simons, D.G.This contribution presents sediment classification results derived from different sources of data collected at the Dordtse Kil river, the Netherlands. The first source is a multibeam echosounder (MBES). The second source is measurements taken with a gammaray scintillation detector, i.e., the MultiElement Detection System for Underwater Sediment Activity (Medusa), towed over the sediments and measuring sediment natural radioactivity. Two analysis methods are employed for sediment classification based on the MBES data. The first is a Bayesian estimation method that uses the average backscatter data per beam and, therefore, is independent of the quality of the MBES calibration. The second is a modelbased method that matches the measured backscatter curves to theoretical curves, predicted by a physicsbased model. Medusa provides estimates for the concentrations of potassium, uranium, thorium, and cesium, known to be indicative for sediment properties, viz. mean grain size, silt content, and the presence of organic matter. In addition, a hydrophone attached to the Medusa system provides information regarding the sediment roughness. This paper presents an intercomparison between the sediment classification results using the abovementioned methods. It is shown that although originating from completely different sources, the MBES and Medusa provide similar information, revealing the same sediment distribution.backscatter; Bayes methods; geochemistry; geophysical techniques; hydrophones; natural radioactivity hazards; rivers; scintillation counters; sediments; soil pollutionAcoustical Society of America
20140201Control & Operations)uuid:fdd34e7403a7458fbb8940640a312e74Dhttp://resolver.tudelft.nl/uuid:fdd34e7403a7458fbb8940640a312e74tMethodology for dense spatial sampling of multicomponent recording of converted waves in shallow marine environments7El Allouche, N.; Drijkoningen, G.G.; Van der Neut, J.R.NA widespread use of converted waves for shallow marine applications is hampered by spatial aliasing and field efficiency. Their short wavelengths require dense spatial sampling which often needs to be achieved by receivers deployed on the seabed. We adopted a new methodology where the dense spatial sampling is achieved in the commonreceiver domain by reducing the shot spacing. This is done by shooting one track multiple times and merging the shot lines in a< n effective manner in a separate processing step. This processing step is essential because positioning errors introduced during the field measurement can become significant in the combined line, particularly when they exceed the distance between two adjacent shot positions. For this processing step, a particular shot line is used as a reference line and relative variations in source and receiver positions in the other shot lines are corrected for using crosscorrelation. The combined shot line can subsequently be regularized for further processing. The methodology is adopted in a field experiment conducted in the Danube River in Hungary. The aim of the seismic experiment was to acquire properly sampled convertedwave data using a multicomponent receiver array. The dense spatial sampling was achieved by sailing one track 14 times. After correcting for the underwater receiver positions using the direct arrival, the crosscorrelation step was applied to merge the different shot lines. The successfully combined result is regularized into a densely sampled data set free of visible spatial aliasing and suitable for convertedwave processing.9geophysical techniques; rivers; seismic waves; seismology$Society of Exploration GeophysicistsGeoscience & Engineering)uuid:ef2c2b63c4e44e3fbed257ed98e4454cDhttp://resolver.tudelft.nl/uuid:ef2c2b63c4e44e3fbed257ed98e4454cXDynamics of shallow lateral shear layers: Experimental study in a river with a sandy bed3Sukhodolov, A.N.; Schnauder, I.; Uijttewaal, W.S.J.Shallow lateral shear layers forming between flows with different velocities, though essential for mixing processes in natural streams, have been examined only in laboratory settings using smooth, fixed?bed channels. This paper reports the results of an experimental study of a shear layer in a straight reach of a natural river where the layer, in contrast to the two?dimensional structure observed in the laboratory, is highly three?dimensional. The study included pronounced transverse pressure gradients, which influenced shear layer structure compared to flume experiments. It also introduces an analysis that complements conventional theory on mixing layers. The lateral velocity gradient between the flows downstream from a splitter plate placed in the river, the principal controlling factor, was adjusted for three experimental runs to determine the influence of different gradients on shear?layer dynamics. In each run, detailed three?dimensional measurements of mean and turbulent characteristics were obtained at five cross sections downstream from the splitter plate. Although experimental results agreed with conventional mixing?layer theories with respect to turbulence, the dynamics of the shear layers were dominated by the mean lateral fluxes of momentum. After re?examining the governing equations, we developed a parabolic equation describing the shear layer evolution and several scaling relations for essential terms of the energy budget: mean and turbulent lateral fluxes of momentum, turbulent kinetic energy, and dissipation rates. The study also provides insight into the spectral dynamics of turbulence in the shear layer and clarifies previous observations reported for confluences in natural streams.rivers; confluences; shear layers; turbulenceAmerican Geophysical UnionHydraulic Engineering)uuid:829e0d8afa6d4b098ba5793da681e725Dhttp://resolver.tudelft.nl/uuid:829e0d8afa6d4b098ba5793da681e725ORiverbed sediment classification using multibeam echosounder backscatter dataAmiriSimkooei, A.; Snellen, M.; Simons, D.G.SA method has recently been developed that employs multibeam echosounder backscatter data to both obtain the number of sediment classes and discriminate between them by applying the Bayes decision rule to multiple hypotheses [ Simons and Snellen, Appl. Acoust. 70, 1258 1268 (2009) ]. In deep water, the number of scatter pixels within the beam footprint is large enough to ensure Gaussian distributions for the backscatter strengths and to increase the discriminative power between acoustic classes. In very shallo< w water (<10?m), however, this number is too small. This paper presents an extension of this highfrequency methodology for these environments, together with a demonstration of its performance using backscatter data from the river Waal, The Netherlands. The objective of this work is threefold. (i) Increasing the discriminating power of the classification method: highresolution bathymetry data allow precise bottom slope corrections for obtaining the true incident angle, and the highresolution backscatter data reduce the statistical fluctuations via an averaging procedure. (ii) Performing a correlation analysis: the dependence of acoustic backscatter classification on sediment physical properties is verified by observing a significant correlation of 0.75 (and a disattenuated correlation of 0.90) between the classification results and sediment mean grain size. (iii) Enhancing the statistical description of the backscatter intensities: angular evolution of the Kdistribution shape parameter indicates that the riverbed is a rough surface, in agreement with the results of the core analysis.acoustic signal processing; backscatter; Bayes methods; correlation methods; fluctuations; Gaussian distribution; rivers; sediments; signal classificationRemote Sensing)uuid:42616303ea1041dead13fbce2c1f8739Dhttp://resolver.tudelft.nl/uuid:42616303ea1041dead13fbce2c1f8739tA modelbased method for reducing the sound speed induced errors in multibeam echosounder bathymetric measurements%Snellen, M.; Siemes, K.; Simons, D.G.rWe present a method for accurately estimating the bathymetry from multibeam echosounder (MBES) traveltime measurements in environments with large variations in the water column sound speeds (both temporally and spatially). In this type of environments the water column sound speeds at the time of the MBES transmission are often not known, preventing a reliable conversion from the measured traveltimes to bathymetry. In addition, accurate sound speed information is required for the MBES beamsteering process. Situations where information regarding the prevailing sound speeds is insufficient occur, for example, in estuaries where fresh river water mixes with seawater. The method fully exploits the redundancy in the MBES measurements obtained from the overlap of adjacent swathes. It searches for those water column sound speeds that result in a maximum agreement in the bathymetry along the overlapping swathes. The GaussNewton method is employed for the optimization. This method is very efficient, requiring a few iterations only and therefore very well suited for processing the large datasets as typically obtained by the MBES. From simulations it is shown that the method performs well and allows for an almost exact determination of the bathymetry and sound speeds. In principle, the method eliminates the need for sound speed measurements, as long as sufficient overlap exists.\bathymetry; oceanographic techniques; rivers; seafloor phenomena; seawater; underwater soundIEEE)uuid:234c6156f82841e6ad32f5e8e2816989Dhttp://resolver.tudelft.nl/uuid:234c6156f82841e6ad32f5e8e2816989UThe impact of changes in sediment supply and sealevel on fluviodeltaic stratigraphyHoogendoorn, R.M.Kroonenberg, S.B. (promotor)Studies in stratigraphy are often driven by the predicted climate change and possible gains for the oil and gas industry. Because, at present predictions of the development of future deltaic architecture are insufficient. This thesis addresses the problem of qualitative and quantitative understanding of sedimentary systems in two stages. In the first stage the stratigraphy of Holocene delta deposits of the Kura and Mahakam deltas (respectively in Azerbaijan en Indonesia) are studied. Results from these studies provide insights as an analogue to ancient systems and serve as an example for expected future conditions. The results form the Kura delta show a prominent role for the rapid sealevel change of the Caspian Sea, while the results of Mahakam delta suggest an important role for the eustatic Holocene sealevel cu< rve and the absence of floods of the Mahakam River. Information obtained from studies in a similar context have the potential to reduce uncertainties and increase confidence in models. The second stage of this thesis covers the development of a processresponse simulation model to assess the impact of changes in sediment supply and sealevel on fluviodeltaic stratigraphy. Anticipating on the dominant role of sediment supply on fluvial dominated deltas, a choice is made for a detailed investigation in how to incorporate good estimates of sediment supply in the numerical model, that enable to explore the possibilities of using a probabilistic approach instead of a deterministic output or geostatistical analysis.Hdeltas; rivers; caspian sea; borneo; stochastic modelling; probabilities)uuid:1107be4127fb430ca63c09fe839fc928Dhttp://resolver.tudelft.nl/uuid:1107be4127fb430ca63c09fe839fc928KSediment exchange between the main channel and the groyne fields of a riverYossef, M.F.M.Report on a physical scale model test in the Fluid Mechanics lab on the effect of groynes on the bed and sediment transport in rivers.Qgroynes; rivers; river morphology; sediment transport; Delft Cluster; DC 03.03.04report
Delft Cluster)uuid:ae661060550947de8f83bf110c77a4e6Dhttp://resolver.tudelft.nl/uuid:ae661060550947de8f83bf110c77a4e6hEnvironmental flow requirements for rivers: An integrated approach for river and coastal zone managementMarchand, M.#rivers; coasts; environmental flows)uuid:115c96a36c4e48c1a698f831829d184cDhttp://resolver.tudelft.nl/uuid:115c96a36c4e48c1a698f831829d184cSA linear approach for the evolution of coherent structures in shallow mixing layers&Van Prooijen, B.C.; Uijttewaal, W.S.J.rThe development of large coherent structures in a shallow mixing layer is analyzed. The results are validated with experimental data obtained from particle tracking velocimetry. The mean flow field is modeled using the selfsimilarity of the velocity profiles. The characteristic features of the downstream development of a shallow mixing layer flow, like the decrease of the velocity difference over the mixing layer, the decreasing growth of the mixing layer width, and the transverse shift of the center of the mixing layer layer are fairly well represented. It turned out that the entrainment coefficient could be taken constant, equal to a value obtained for unbounded mixing layers: ? = 0.085. Linearization of the shallow water equations leads to a modified Orr Sommerfeld equation, with turbulence viscosity and bottom friction as dissipative terms. Growth rates are obtained for each position downstream, using the model for the mean flow field. For a given energy density spectrum at the inflow boundary, integration of the growth rates along the downstream direction yields the spectra at various downstream positions. These spectra provide a measure for the intensity and the length scale of the coherent structures (the dominant mode). The length scales found are in good agreement with the measured ones. The length scale of the most unstable mode appears much larger than the length scale of the dominant mode. Obviously, the longevity of the coherent structures plays a significant role. Three growth regimes can be distinguished: in the first regime the dominant mode is growing, in the second regime the dominant mode is dissipating, but other modes are still growing, and in the third regime all modes are dissipating. It is concluded that the development of the coherent structures in a shallow mixing layer can fairly well be described and interpreted by the proposed linear analysis.crivers; channel flow; mixing; turbulence; flow instability; flow visualisation; hydrology; fractalsAmerican Institute of Physics)uuid:b9545ba724234c20ace20e1cd799d18aDhttp://resolver.tudelft.nl/uuid:b9545ba724234c20ace20e1cd799d18a2The effect of groynes on rivers: Literature review Groynes are structures constructed at an angle to the flow in order to deflect the flowing water away from critical zones. They are made of stone, gravel, rock, earth,< or piles, beginning at the riverbank with a root and ending at the regulation line with a head. They serve to maintain a desirable channel for the purpose of flood control, improved navigation and erosion control. In the River Rhine, which is considered the backbone of Northwestern European waterways network, the primary objective of groynes is to provide a fairway of sufficient depth and width. For example the River Waal, the most important branch of the Rhine River in the Netherlands is regulated by around 500 groyne. Within the framework of the research project "Space for the Rhine Branches" several measures have been devised to achieve a decrease of the water levels at peak discharges, one of those measures, is lowering of the existing groynes. The rationale behind this proposal is that; due to largescale erosion of the lowwater bed through the past decades, the groynes are now higher than necessary for keeping the main channel at depth. Lowering the groynes along certain reaches of the river would result in a reduction of the effective roughness during high water conditions thus, increasing the river's flood conveyance capacity. If the groynes are lowered, however, the balance of hydrodynamic forces acting on the groynefields will change, and there will be a largescale morphological impact. To identify this impact, a thorough understanding to the effect o f groynes on the morphology of the river is necessary. The sediment exchange between the groynefields and the main channel needs to be more comprehensible. The purpose of this report is to acquire the background knowledge required to study the effect of groynes on a river. The characteristics of the existing groynefields along the Waal River are presented. The hydrodynamic and morphological impact of groynes on a river is described. Moreover, because navigation plays an important role in the interaction between the groyne fields and the main channel, the navigation induced water motion and its effect on the flow in groynefields is described. Finally, a review of some prediction attempts to the interaction between the groynefields and the main channel is presented.+groynes; rivers; Delft Cluster; DC 03.03.04)uuid:40545be39d3241f39674cd817fa8ca52Dhttp://resolver.tudelft.nl/uuid:40545be39d3241f39674cd817fa8ca524Onedimensional models for mountainriver morphology
Sieben, A.In this report, some classical and new simplifications in mathematical and numerical models for river morphology are compared for conditions representing rivers in mountainous areas (high values of Froude numbers and relatively large values of sediment transport rates). Options for simplification are summarized based on time scale of hydrographs and length scales of river geometry. This results in concepts based on quasisteady and/or quasiuniform flow assumptions. Additionally, the behaviour of frictionless, critical flow with a mobile bed is considered. The nonlinear interaction between changing flow and morphology is investigated for different values of the Froude number. Neglecting this interaction in numerical solution procedures appears to affect the solution. Also, mass and momentum contributions of sediment in transport on the mixture of water and sediment are analyzed. It is shown that errors due to simplification in numerical models for river morphology vary with the different up or downstream propagating waves that are part of the solution. Conclusions further refer to the importance of wave nonuniformity (wave length, dominance of friction), Froude number and bed mobility on the error made when using simplified modelling concepts. Application of simplified modelling concepts based on subcritical lowland rivers in the modelling of transcritical and supercritical flows can result in significant errors.morphology; riversTU Delft)uuid:ae7133834e7643a19d1148f08ae7e66dDhttp://resolver.tudelft.nl/uuid:ae7133834e7643a19d1148f08ae7e66d5Advection models of longitudinal dispersion in riversKranenburg, C.A derivation is presented of a general crosssection averaged model o< f longitudinal dispersion, which is based on the notion of the advection of tracer particles. Particle displacement length and particle travel time are conceived as stochastic variables, and a joint probability density function is introduced to arrive at an integral advection model for the crosssection averaged concentration. Starting from this model special advection models known from the literature are obtained in a consistent way. These models, in which only the travel time is a stochastic variable, predict skewed tracer concentration contributions of the kind observed in the field, but satisfy the condition of approach to Gaussian behaviour for large spreading times. A relationship between the particle displacement length and the longitudinal dispersion coefficient is derived. The application of advection models to nonuniform rivers and the relationship with the deadzone model are outlined.)uuid:5e46fc03dde34decb97ac00ef4c9dffbDhttp://resolver.tudelft.nl/uuid:5e46fc03dde34decb97ac00ef4c9dffbIA study on onedimensional and discontinuous river flows with mobile bedsThis report focusses on discontinuous behaviour of hydraulics and morphology in rivers. The varying widths, slopes and bed levels that can be observed in mountain rivers can induce rapid, or discontinuous changes at a short lengthscale. When present, these discontinuities have a major impact on changes in water and bed levels during floods. In this study, existing theories on discontinuous solutions are applied to river flows with mobile beds. The propagation rate and stability of a discontinuity are analysed with the Lax shockwave criterion. Effects of transitions in flow regime are described qualitatively by solving the RankineHugoniot relations. Attention is paid to the effect of river bed mobility on discontinuous flows.)uuid:e659e47c740b45119442f1a2adfdfaebDhttp://resolver.tudelft.nl/uuid:e659e47c740b45119442f1a2adfdfaeb?Notes on the mathematical modelling of alluvial mountain riversThe ability of describing and predicting hydraulic and morphological phenomena in mountain rivers is limited, partially due to the limits of deterministic approaches where stochastic effects in sediment supply and water inflow are extremely significant, and partially due to the very specific conditions that can be observed in mountain rivers, that complicate the modelling. The dynamics of morphology and hydraulics of mountain rivers must be known when applying numerical modelling procedures to mountain rivers. Simplifying a complex, nonuniform geometry significantly affects the behaviour of the model at high values of the Froude number. The number and type of boundary conditions to be prescribed at a boundary can change with flow regime. Hydraulic and morphological changes in supercritical flows are coupled and transversal effects are significant. The mathematical models discussed are a singlelayer model and a double layer model conform Ribberink (1987). With the help of the characteristics, the models are analysed and compared. Analysing the characteristic surface yields indispensible insight in the twodimensional behaviour of the mathematical models. To prevent the mathematical model from being elliptical, the thickness of the mixing layer has a maximum. This value is investigated, approximated and evaluated. It appears that the behaviour of the model can be significantly affected by the model parameters (hydraulic as well as morphological). Regarding the selection between onedimensional and twodimensional modelling, it can be concluded that transverse effects have a significant influcence on the behaviour of the model for Froude near unity. Conclusions in this report stress the need for research on the modelling of complex geometry for flow with higher values of Froude and the prediction of the model parameters used (such as mixinglayer thickness and sediment fluxes) at varying flow conditions.)uuid:693de6a8eefa48d0bb1822ba61988e80Dhttp://resolver.tudelft.nl/uuid:693de6a8eefa48d0bb1822ba61988e80aAnalysis of the transport of a pollution cloud in the< UpperRhine River between Lake of ConstanceVan Kuik, C.A.; Van Mazijk, A./ In the onedimensional 'Rhine Alarm Model' differences between the actual travel time of a pollution cloud, originating from an instantaneous release of an accidental spill, and the travel time, based on the flow velocity is represented by a lag coefficient. In the model this lag coefficient is defined by the relative difference between these two travel times. This paper presents the results of a study on the influence of tributaries and suppressed flow by weirs on the lag coefficient in general and on the influence of the River Aare and the suppressed flow by water power stations on this coefficient in the UpperRhine River between Lake of Constance and Basel especially. Also the influence of incompletely transversal mixing in the vicinity of the point of release at a river bank as a special case of a polluted tributary is discussed. In the study analytical and numerical approaches were applied. For the numerical approach a twodimensional transport model of the "Versuchsanstalt fUr Wasserbau (VAW)" (Hydraulic Research Institute) of the ETHZiirich (Federal University of Technology of Zurich) was used. The main conclusion is that the behaviour of the lag coefficient along the UpperRhine River is strongly influenced by sudden increases of the flow velocity at power stations, due to the differences in waterdepth upstream and downstream of the station, and at the AareRhine confluence, due to the large discharge ratio of these river branches. The outcome of these flowvelocity discontinuities is a relatively large negative value of the lag coefficient upstream of the discontinuity and a relatively large positive value downstream. This is because upstream of the discontinuity the transport velocity of the centroid of the pollution cloud is already influenced by the larger flow velocity downstream of the discontinuity as soon as the front of the cloud has passed the discontinuity. Downstream of the discontinuity the transport velocity of the centroid is still influenced by the smaller flow velocity upstream of the discontinuity as long as the tail of the cloud remains upstream of the discontinuity. Case studies on the UpperRhine River between Lake of Constance and Basel show good fits of the calibrated values of the lag coefficient in the Rhine Alarm Model with the results of the twodimensional transport model.dispersion; rivers)uuid:ff77dce819bc461297b13464de96e81aDhttp://resolver.tudelft.nl/uuid:ff77dce819bc461297b13464de96e81aRiver engineeringDe Vries, M.One dimension models  basic eauations, analytical models, numberical models. One dimensional models suspended load, roughness and resistance of river beds. Solving river problems  tools, flood mitigation, bank protection.river engineering; rivers
lecture notes*TU Delft, Department Hydraulic Engineering)uuid:a2433bee65a94deea7ca14cbd11be206Dhttp://resolver.tudelft.nl/uuid:a2433bee65a94deea7ca14cbd11be206?Hydraulics and morphology of mountain rivers; literature survey
Sieben, J.Present knowledge on fluvial processes in mountain rivers should be expanded to enable the development of projects dealing with mountain rivers or mountainriver catchment areas. This study reviews research on hydraulic and morphological features of mountain rivers. A major characteristic of mountain rivers is the variability of the hydraulic and morphological parameters. Flows can change from extremely nonuniform flow over large roughness elements at low stages to relatively uniform flow at high stages. The irregularity of geometry complicates the modelling of the turbulent, nonuniform and/or unsteady behaviour of water and sediment. It can be concluded that, due to the complexity of the conditions observed, a proper, general description of sediment movements in mountain rivers is not possible yet. Description or prediction of morphological developments at present is limited to exceptionally isolated phenomena. Morphological responses of a river to a flood depend on (i) the sizedistribution of the bed< material and (ii) the distribution in time and place of hydrographs and sediment supply. The effects and relevancy of extreme hydraulic conditions have to be investigated, to enable description and prediction of longterm morphological evolution. Considering the importance of extreme, and subsequently lowfrequency variables, the prospect of theoretical simulation models of morphological processes in mountain rivers seems rather remote.)uuid:13b8565a9b494d35889725b430b5a320Dhttp://resolver.tudelft.nl/uuid:13b8565a9b494d35889725b430b5a320 Use of models for river problemsIn Chapter 2 of this report an overview is given on fluvial processes involved in the modelling discussed. Chapter 3 is concerned with scale models, whilst Chapter 4 deals with numerical models. The main problems treated are, firstly, modelling of the water movement, followed by sediment transport and morphology. Attention is also given to the dispersion of dissolved matter and problems associated with ice. The 'tools' for scale models and numerical models are given only little attention. For scale models the tools are instruments and control systems. For numerical models numerical schemes are involved. A good introduction can be found in Vreugdenhil (1989). In Chapter 5 guidance is given on the selection of the type of model for river problems, though this has to be of a general nature.8rivers; hydraulic models; modelling; mathematical modelsUnesco)uuid:4ca0340fa5e447a4a3467c71a7d209d5Dhttp://resolver.tudelft.nl/uuid:4ca0340fa5e447a4a3467c71a7d209d5TModelling of river morphology with nonorthogonal horizontal curvilinear coordinates
Mosselman, E.[A numerical twodimensional model for river morphology is extended with bank erosion. The model is formulated in curvilinear coordinates. This allows the use of a boundaryfitted computational grid, suited for rivers with a curved centreline and a nonuni form width. Dealing with nonhomogeneous bank erodibility is shown to require a nonorthogonal coordinate system. This enables the use of simple algebraic grid generators, but complicates the transformed equations. A main feature of the present study is that all coordinate derivatives in the transformed equations are replaced by grid properties that are invariant for grid rotation, such as local grid skewness and grid line divergences. This facilitates the physical interpretation of transformation terms and the estimation of their contribution to the solution. The model is verified by comparing its results with results from the original model, and by comparing computations on nonorthogonal grids with a computation on an orthogonal grid. An examination of the truncation error reveals the importance of a smooth grid point distribution for accuracy.)uuid:0734f459096b426b9020d9f9a48ddf54Dhttp://resolver.tudelft.nl/uuid:0734f459096b426b9020d9f9a48ddf54(Simulation of meandering river processesCrosato, A.A simple mathematical model for the simulation of river meandering processes is presented and analysed. The model is schematized as follows: computation of steadystate flow field and riverbed topography; and computation of bank erosion rate as a function of the nearbank hydraulic and morphological properties. The model is linear for the prediction of flow field and river bed topography, while geometrical nonlinearities arise from the bank erosion equation. The flow and river bed model is derived by fully coupling flow field, bed topography and sediment transport and it (roughly) accounts for the secondary flow momentum convection.)uuid:a1d108a6ecf346c4ae673eb999c51ab3Dhttp://resolver.tudelft.nl/uuid:a1d108a6ecf346c4ae673eb999c51ab3CA theoretical model for suspended sediment transport in river bendsTalmon, A.M.A two dimensional depthaveraged model for the concentration field of suspended sediment in river bend flow is formulated. Transport of suspended sediment in horizontal and vertical directions is modelled. Convection by the main and secondary flow and turbulent diffusion are incorporated. The model is capable of computing the < exchange of sediment with the bedload layer adjacent to the bed. The model is based on the three dimensional convectiondiffusion equation formulated in a cylindrical bed following coordinate system. Nonorthogonality of the coordinate system is included. The concentration field is modelled by a first order asymptotic solution of the convectiondiffusion equation. The zeroth order contribution to the solution is given by equilibrium shape concentration verticals, the first order contribution is due to the convection by the flow. The result is formulated in depthaveraged variables. The time and length scales of the model are computed. These scales are significantly affected by the choice of reference level, the choice of boundary condition at this level, the suspension parameter and the Chezy coefficient. The model will have to be calibrated and verified by measurements and numerical computations.)uuid:1ca904d12b9c4eb3ae7c0e57ba722dafDhttp://resolver.tudelft.nl/uuid:1ca904d12b9c4eb3ae7c0e57ba722dafATheoretical investigation on dischargeinduced riverbank erosion'Bank erosion is incorporated in onedimensional and twodimensional horizontal models for river morphology. The banks are assumed to consist of a fraction of cohesive material, which becomes washload after being eroded, and a fraction of granular material, with the same properties as the material of the bed. The banks are taken to be eroded by discharge flow causing lateral entrainment of lower parts of the banks and nearbank bed degradation, both inducing mass failure of upper parts of the banks. Theoretical analyses are performed in order to reveal the influence of bank erosion on the morphological system. From an analysis of characteristics of the onedimensional model it is concluded that generally river widths cannot be stabilized by protecting certain carefully chosen bank section~ only, and that computations of river planimetry can be decoupled from the computations of flow and bed topography. A linear analysis of the onedimensional model is used to clarify the interactions between bank and bed disturbances, whereas a linear analysis of the twodimensional model is used to demonstrate that the input of bank erosion products decreases transverse bed slopes, but hardly influences the wave lengths and damping lengths of flow and bed topography in natural rivers with moderately migrating banks.)uuid:58bc70ac2d164d9b907db397a3c2544cDhttp://resolver.tudelft.nl/uuid:58bc70ac2d164d9b907db397a3c2544c8Morphological modelling for rivers with nonuniform flowRibberink, J.S.LIn Chapter I a derivation of the equations and an extension of the mathematical model will be carried out. The sedimentmixture is separated in a number of fractions  each with a representative grain size  and the equations describing the sedimentmovement are split up for every fraction separately. In order to get some insight in the new model in Chapter 2 a restriction will take place to sedimentmixtures consisting of only two sedimentfractions. As a result only one extra dependent variable viz. the probability of one of the fractions, comes into the equations. Moreover the characteristic directions and relations belonging to the set of partial differential equations will be derived mainly in order to obtain information concerning the timescales of changes in bedlevel and bedcomposition; also the interaction between these changes and the influence of some determining parameters will be studied. In Chapter 3 specific calculations will be carried out of the characteristic directions and relations and the influence of two possible concepts for a transportformula per fraction is studied. In Chapter 4 four simple applications of the mathematical model for two sedimentfractions are treated. The watermotion is simplified in order to be able to carry out the calculations partly by hand. In Chapter 5 a summary and conclusions are given.=rivers; sedimenttransport; river morphology; nonuniform sand)uuid:e25fd3bd4aeb4fcfbdf3f15ce8e2b340Dhttp://resolver.tudelft.nl/uuid:e25fd3bd4aeb4fcf<bdf3f15ce8e2b340Regulation structuresVan Bendegom, L.?rivers; river regulation structures; groynes; revetments; weirs
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