In the south portion of the Dutch coast is located the Sand Engine, a 21.5 million m3 experimental mega-nourishment that was built in 2011. This intervention created a discontinuity in the previous straight sandy coastline, altering the local hydrodynamics in a region that is influenced by the Rhine River ROFI. Estimates of the centrifugal acceleration directly after construction of the Sand Engine showed that its curved shape impacted the cross-shore flow, suggesting that the Sand Engine might have played a role in controlling the cross-shore exchange currents during the first three years after the completion of the nourishment. Presently, the curvature effects are minute owned to the morphodynamic evolution of the Sand Engine. Observations document the development of strong baroclinic-induced cross-shore exchange currents dictated by the intrusion of the river plume fronts as well as the classic tidal straining which are found to extend further into the nearshore (from 12 to 6 m depth), otherwise believed to be a mixed zone.

In the inner shelf, shoaling waves are as effective in mobilizing sediment as the other co-existing flows. The influence of stratification on the hydrodynamics is translated into near-bed shear velocity in the layer immediately above the sea floor. The tide-induced bed shear stress is able to periodically agitate the bed near the peaks of flood and ebb cycles mostly during spring tides. Results from observations suggested that, under stratified conditions, relatively high values of bed shear stress are sustained for a prolonged period of time. The results also revealed that the non-tidal flow, such as the wind-induced flow, plays a role in controlling the bed mobility. However, wave-induced bed shear stress in general does not set sediment in motion during fair weather conditions and thus the stirring role of the waves is mostly important during storms.

The co-exiting near-bed flows in the inner shelf are responsible for moulding the seafloor so that the resulting types of bedforms can reveal important information on the hydrodynamic forcings that dictate the sediment mobility. Observations showed that 56% of the ripples in the Dutch inner shelf are classified as current ripples. Wave ripples occur only during storm conditions, comprising 3%. The frequency of occurrence of transitional bed types composes 23% and poorly developed ripples is found to develop mostly during neap tides making up 15% of the observed bed types. The feedback of the different types of bedforms on the overlying boundary layer plays a fundamental role in the dynamics of the sediment load.

The morphological response of the bed to the stratified and non-stratified tidal flow leads to differentiations of the ripple migration as well as the sediment transport modes (bedload and suspended load). The bedforms at the measurement site are strongly controlled by tides so that their behavior exhibits not only a spring-neap signature, but also a distinct semi-diurnal fluctuation. Under the influence of the Rhine ROFI, the bedform mean dimensions (ripple height and wavelength) are reduced, indicating that their development is affected by the stratified tidal flow. In the absence of (ambient) stratification, the tidal current ripples are more developed, attaining relatively larger dimensions. The net alongshore bedload transport is south-directed, whereas the net alongshore suspended load is north-directed regardless of stratification. Moreover, the net alongshore bedload transport is higher during stratified conditions but the net alongshore suspended transport is smaller. Regarding the cross-shore sediment transport, the findings show that ambient stratification promotes onshore-directed bed- and suspended load net transport. The gross suspended transport rates are 10 times greater than the gross bedload transport rates.","stratification; bedforms; sediment transport","en","doctoral thesis","","","","","","","","","","","","","","" "uuid:b51ea764-4e48-4247-b24a-37e05b7fa7d6","http://resolver.tudelft.nl/uuid:b51ea764-4e48-4247-b24a-37e05b7fa7d6","Modeling the Transition to High Sediment Concentrations as a Response to Channel Deepening in the Ems River Estuary","Dijkstra, Y.M. (TU Delft Mathematical Physics); Schuttelaars, H.M. (TU Delft Mathematical Physics); Schramkowski, G.P. (TU Delft Mathematical Physics; Flanders Hydraulics Research); Brouwer, R.L. (TU Delft Mathematical Physics; Flanders Hydraulics Research)","","2019","Many estuaries are strongly modified by human interventions, including substantive channel deepening. In the Ems River Estuary (Germany and Netherlands), channel deepening between the 1960s and early 2000s coincided with an increase in the maximum near-bed suspended sediment concentration from moderate (∼1 kg/m

multi-fraction sediment transport due to subtidal and subaerial processes simultaneously. The Windsurf framework couples separate model cores for subtidal morphodynamics related to waves and currents and storms and aeolian

sediment transport. The Windsurf framework bridges three gaps in our ability to model long-term coastal morphodynamics: differences in time scales, land/water boundary and differences in meshes.

The Windsurf framework is applied to the Sand Motor mega-nourishment. The Sand Motor is virtually permanentlyexposed to tides, waves and wind and is consequently highly dynamic. In order to understand the complex

morphological behavior of the Sand Motor, it is vital to take both subtidal and subaerial processes into account. The ultimate aim of this study is to identify governing processes in aeolian sediment transport estimates in coastal environments and improve the accuracy of long-term coastal morphodynamic modeling.

At the Sand Motor beach armoring occurs on the dry beach. In contrast to the dry beach, no armor layer can be established in the intertidal zone due to periodic flooding. Consequently, during low tide non-armored intertidal beaches are susceptible for wind erosion and, although moist, may provide a larger aeolian sediment supply than the vast dry beach areas. Hence, subtidal processes significantly influence the subaerial morphology and both need to be accounted for to understand the long-term aeolian morphodynamic behavior of the Sand Motor.","hydrodynamics; sediment transport; morphodynamics; dunes and ecomorphology; numerical modelling; coasts and climate","en","conference paper","","","","","","","","","","","","","","" "uuid:c939962d-1cef-4701-9840-ae005595ac47","http://resolver.tudelft.nl/uuid:c939962d-1cef-4701-9840-ae005595ac47","Beach growth driven by intertidal sandbar welding","Cohn, Nicholas (Oregon State University); Ruggiero, P (Oregon State University); de Vries, S. (TU Delft Coastal Engineering); García-Medina, Gabriel (Oregon State University)","Aagaard, T. (editor); Deigaard, R. (editor); Fuhrman, D. (editor)","2017","Seasonal variability in wave conditions drive corresponding cycles of erosion and accretion along sandy beaches. Despite the fact that these oscillations are well documented at numerous sites throughout the world, the physical processes driving beach recovery remain poorly understood. Using field data from a low sloping, dissipative beach in the U.S. Pacific Northwest we show that the onshore migration of intertidal sandbars contributes to beach growth in a rapidly prograding system. Over a six week period two intertidal sandbars are shown to migrate onshore resulting in the generation of a low relief berm and local beach width increases of up to 20 m. Although significant alongshore variability of intertidal morphological change was observed, a 2.5 km stretch of coast is shown to experience beach growth as a result of intertidal bar welding.","beach recovery; intertidal sandbars; sediment transport; morphodynamics; shoreline change","en","conference paper","","","","","","","","","","","","","","" "uuid:547d2dfd-672e-4b6d-aa96-45ef67b05023","http://resolver.tudelft.nl/uuid:547d2dfd-672e-4b6d-aa96-45ef67b05023","Tidal and sediment dynamics in a fine-grained coastal region: A case study of the Jiangsu coast","Yao, P.","Stive, M.J.F. (promotor); Wang, Z.B. (promotor)","2016","The Jiangsu coast is located in eastern China bordering the South Yellow Sea. It is strongly affected by the semi-diurnal tides. Both the tidal range and the tidal current vary greatly in space due to local tidal wave systems and morphologies. The radial tidal current pattern identified at the central coast is suggested to play a primary role in the evolution of a large-scale radial-shape sand ridge system. Another feature of the Jiangsu coast is the diversity of the bottom sediments with pronounced silt content. Inspired by the characteristics of both the hydrodynamics and sediment dynamics throughout the Jiangsu coast, this thesis focuses on advancing our understanding of the coastal tidal dynamics and the resulting sediment transport. Regarding the radial tidal current pattern at the central Jiangsu coast, there have been plenty of studies exploring relevant formation mechanisms. A generally accepted inference is that the radial tidal current pattern is a consequence of the interaction between the northern rotating tidal wave system and the southern progressive tidal wave. In this study, we examine the emergence of the radial tidal current in a schematized semi-enclosed tidal basin by introducing the tidal Current Amphidromic Point (CAP) and the tidal current inclination angles. After comprehensive numerical experiments, we find that the overall basin scale and the cross-basin phase difference play roles in the emergence of the radial tidal current. The radial tidal current only has an opportunity to emerge in a basin where the basin length (L) is larger than width (B) (i.e. L/B>1), a lateral depth difference exists or the offshore incoming tidal wave has an oblique angle. The Yellow Sea is featured by these aforementioned prerequisites favouring the emergence of the radial tidal current. Furthermore, we discover that the radial tidal current is related to the cross-basin CAP distribution pattern. When the radial tidal current emerges, the focal point is the CAP related to the velocity vectors rotating anti-cyclonically in the Northern Hemisphere. The CAP distribution deserves more attention for the identification of the radial tidal current pattern. To understand the sediment dynamics in a silt-enriched environment in more detail, we have carried out a series of flume experiments under various wave and current conditions with field-collected silt-sand mixtures. According to the experiments, we find that the silt fraction has different features originating from both the sand fraction and the clay fraction. A high concentration layer is observed near the bottom together with ripples under pure wave conditions. Sediment concentrations inside the high concentration layer are quasi-stationary with the bulk Richardson number approaching a constant value. The thickness of the high concentration layer can be scaled with approximately two times the damped wave boundary layer thickness. Thus, the wave motion induced turbulence is considered to be the main reason generating the high concentration layer. Moreover, suspensions inside the high concentration layer have a certain amount of sand content, which is different from the fluid mud in the cohesive muddy bed. For the vertical concentration profile, the silt fraction is also distributed differently from the sand fraction, since the silt concentration decreases logarithmically within high concentration layer, while it is homogeneously distributed outside the high concentration layer. Considering the specific features of the silt fraction, we recalibrated the formulations of van Rijn (2007a, b) based on our experiments and further developed a multi-fraction sediment transport model to predict the vertical concentration profile for silt and sand classes, and then tested the existing sediment formulations. The results show a promising agreement with the measurements, for both wave-only and wave-with-current conditions. Finally, the Jiangsu Regional Model is set up utilizing the aforementioned findings on tides and sediments. The Jiangsu Regional Model is used to examine whether our existing knowledge can be integrated for a relatively long-term (i.e. time scale of years) predictions on the sediment transport and the morphological changes of the Jiangsu coast. To this end, we first reasonably construct the bed composition throughout the model domain. Subsequently, the model is calibrated and validated against two independent measurements on water level, flow velocity and the sediment concentration. The results indicate that the present model can produce good results. The simulated annual-averaged SSCs depict a high value in the coastal region between the Old Yellow River Delta and the northern Radial Sand Ridge Field. The simulated morphological changes show a spatially distributed alternating-erosion-sedimentation pattern in the Old Yellow River Delta rather than pure erosion. Over the Radial Sand Ridge Field, the ridges are continuously growing and the adjacent tidal channels are deepening. The simulated annual-averaged tide-induced sediment budget shows that the northern (i.e. the Old Yellow River Delta) and southern (i.e. the southern Radial Sand Ridge Field) Jiangsu coast are under erosion, while the central coast (i.e. the northern and central Radial Sand Ridge Field) is still in progradation. Furthermore, the simulated sediment bed in the Old Yellow River Delta shows a gradually coarsening trend while an overall fining trend is pronounced in the northern Radial Sand Ridge Field. All these long-term results are in good agreement with observation-based estimations. The present modelling framework indeed has the ability for simulating sediment transport and morphological changes over a relatively long time span (i.e. time scale of years). This thesis addresses series of findings on the radial tidal current pattern, characteristics of the silt-dominated sediments as well as the sediment transport and morphological changes along the Jiangsu coast. The proposed modelling approaches can serve as a basis and provide information on large-scale hydrodynamics and sediment dynamics for the management and planning of the Jiangsu coast. Future studies may be focused on (1) detailed investigation on the influencing factors on the emergence of the radial tidal current by the CAP system distribution; (2) the physics of the layered-bed system (i.e. the hard layer under ripples) for silt dominated mixtures; (3) improving the computational efficiency of the Jiangsu Regional Model for longer time scale (i.e. tens of years).","tides; tidal wave system; tidal current system; silt dynamics; sediment transport; Jiangsu coast","en","doctoral thesis","","","","","","","","2016-03-21","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:d9e3f248-06fb-48d6-a767-8589ec4b6091","http://resolver.tudelft.nl/uuid:d9e3f248-06fb-48d6-a767-8589ec4b6091","Development and Extension of An Aggregated Scale Model: Part 1 – Background to ASMITA","Townend, I (University of Southampton); Wang, Zhengbing (TU Delft Coastal Engineering); Stive, M.J.F. (TU Delft Coastal Engineering); Zhou, Z. (Hohai University)","","2016","Whilst much attention has been given to models that describe wave, tide and sediment transport processes in sufficient detail to determine the local changes in bed level over a relatively detailed representation of the bathymetry, far less attention has been given to models that consider the problem at a much larger scale (e.g. that of geomorphological elements such as a tidal flat and tidal channel). Such aggregated or lumped models tend not to represent the processes in detail but rather capture the behaviour at the scale of interest. One such model developed using the concept of an equilibrium concentration is the Aggregated Scale Morphological Interaction between Tidal basin and Adjacent coast (ASMITA). In this paper we provide some new insights into the concepts of equilibrium, and horizontal and vertical exchange that are key components of this modelling approach. In a companion paper, we summarise a range of developments that have been undertaken to extend the original model concept, to illustrate the flexibility and power of the conceptual framework. However, adding detail progressively moves the model in the direction of the more detailed process-based models and we give some consideration to the boundary between the two. Highlights

• The concept of aggregating model scales is explored and the basis of the ASMITA model is outlined in detail;

• The relationship between dispersion as used in fast-scale process-based models and the horizontal exchange used in aggregated models is explored;

• The basis for formulating suitable equilibrium relationships is explained; • Alternative ways to include advection and dispersion are examined.

200 kg/m3) and primarily Newtonian, turbulent flows (van Maren et al., 2009a). This reach is characterized by two special, and possibly unique, hydrodynamic and sediment transport phenomena that are associated with hyperconcentrated flow: a downstream increasing peak discharge (at a rate far exceeding the contribution from tributaries) during hyperconcentrated floods, and a downstream decreasing runoff due to water diversions. Assuming spatially continuous diversions along a constant-width channel, previous studies suggest a longitudinally convex bed at the equilibrium state. However, the validity of a convex bed profile, for discrete diversions in natural channels of longitudinally varying width, remains to be justified. Also, such equilibrium analysis does not reveal the morphological time scale (MTS) associated with water diversions. Moreover, though many explanations have previously been proposed for the peak discharge increase, they have focused on only one possible mechanism (e.g., bed roughness change, bed erosion, floodplain influences) and no consensus has been achieved. The underlying physics still remain largely unknown. Research efforts are therefore needed to further investigate these two issues, which comprise the main work of the present PhD research and this thesis. For the study of the downstream peak discharge increase phenomenon, mathematical modelling is the main research method, together with the field data analysis. High-resolution morphodynamic modelling of complex fluvial processes, such as in a hyperconcentrated flood, has so far been limited by model accuracy or computational efficiency. In order to account for the strong interactions during the hyperconcentrated flood and to acquire accurate and efficient solutions in the field scale, a fully coupled morphodynamic model has first been developed using the finite volume method for structured grids. Physically, this model is based on the concept of non-capacity sediment transport, and it incorporates the effects of sediment density and bed deformation on the flow (both in mass and momentum), as well as the influences of turbulence and sediment diffusions. Numerically, this model combines the high accuracy of high-order upwind schemes and the efficiency of centered schemes by the extension of a recent upwind-biased centered (UFORCE) scheme (Stecca et al., 2010) originally developed for clear flow and scalar transport over a fixed bed, to sediment-laden flows over an erodible bed. For stability, a two-stage splitting approach together with a second order Runge-Kutta method is used for the source terms. Moreover, the full set of governing equations is solved at one time to obtain synchronous solutions in mathematics. The model is verified in a number of dam-break tests, covering a wide range of complex (sediment-laden) flows. It is demonstrated to accurately simulate shock waves and reflection waves, as well as rapid bed deformations at high sediment transport rates. Using this model, the relative role of bed roughness change and bed erosion on the downstream peak discharge increase is then investigated in schematized 1-D channels for two hyperconcentrated floods. The results reveal that although erosion effects may contribute to the downstream discharge increase (especially in case of extreme erosion), for most cases the increase is mainly due to a reduction in bed roughness during peak discharge conditions. Additionally, based on the concept of channel storage reduction, the effects of decreasing bed roughness and (very strong) bed erosion can be integrated in the explanation of the peak discharge increase. Later, this model is also applied to reveal the floodplain influences on the peak discharge increase in schematized 2-D channel-floodplain reaches. The results indicate that the cross-sectional changes of channel erosion and floodplain deposition during hyperconcentrated floods are often limited and that it is difficult to drive a peak discharge increase in the downstream direction. For the study of the water diversion impact, a general theoretical framework is proposed to predict the equilibrium state of the fluvial system, which is applicable to both continuous and discrete water diversions in a longitudinally width-varying channel. Numerical experiments by the SOBEK-RE software (version 2.52.005, Delft Hydraulics, 2005) complement the MTS studies for water diversions. The effects of diversion intensity, diversion placement (discrete and continuous) and diversion schemes (pure water and water-sediment mixture) are also systematically studied. The present work confirms the previous findings that water diversions lead to a decrease of the equilibrium depth with respect to natural conditions and a convex bed in a constant-width channel. Moreover, it reveals that in a widening channel a convex bed also develops under conditions of water diversions, while convex, concave or quasi-linear beds may occur in a narrowing channel. Non-monotonic beds may develop in a strongly narrowing channel, depending on the diversion schemes. On a large spatial scale, diversion placement is less important for the equilibrium development. The MTS for water diversions and natural development are very similar and large, indicating considerable influences of water diversions on river morphology. The present thesis advances our understanding of the long-term impact of water diversions on the evolution of a river.","mathematical modelling; morphology; hyperconcentrated flow; sediment transport; water diversions; dam break","en","doctoral thesis","VSSD","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:9a701423-8559-4a44-be5d-370d292b0df3","http://resolver.tudelft.nl/uuid:9a701423-8559-4a44-be5d-370d292b0df3","Physics of Blown Sand and Coastal Dunes","De Vries, S.","Stive, M.J.F. (promotor)","2013","","sediment transport; wind; dunes; coast","en","doctoral thesis","","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:3d12158b-9940-4d69-a870-4311839ed68b","http://resolver.tudelft.nl/uuid:3d12158b-9940-4d69-a870-4311839ed68b","Detailed simulation of morphodynamics: 3. Ripples and dunes","Nabi, M.; De Vriend, H.J.; Mosselman, E.; Sloff, C.J.; Shimizu, Y.","","2013","We present a 3-D physics-based high-resolution modeling approach to the dynamics of underwater ripples and dunes. The flow is modeled by large eddy simulation on a Cartesian grid with local refinements. The sediment transport is modeled by computing pickup, transport over the bed, transport in the water column, and deposition of rigid spherical particles in a Lagrangian framework. The morphological development of the bed is modeled by a sediment balance equation in which the pickup and deposition from the sediment motion submodels appear as source and sink terms. The model realistically replicated the formation and migration of dunes. Model results showed a good agreement with data from five flume experiments. We subsequently applied the model to investigate the effect of sediment grain size on ripples. Finer sediments were found to yield more superimposed ripples than coarser sediments. Moreover, under the same hydrodynamic conditions, the finer sediments yielded two-dimensional bed forms, whereas for coarser sediment irregularities increased. We extended the tests to pronounced 3-D morphologies by simulating the development of local scour at a pier. The results agreed well with experimental data. The model contributes to unraveling the complex problem of small-scale morphodynamics and may be used in a wide range of applications, for instance, to develop more reliable parameterizations of small-scale processes for application in large-scale morphodynamic models.","river morphodynamics; dunes; ripples; sediment transport; large eddy simulation; pier scour","en","journal article","American Geophysical Union","","","","","","","2014-03-20","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:bafec7d8-2c1c-4ee5-85d6-3353397e3fe3","http://resolver.tudelft.nl/uuid:bafec7d8-2c1c-4ee5-85d6-3353397e3fe3","Detailed simulation of morphodynamics: 2. Sediment pickup, transport, and deposition","Nabi, M.; De Vriend, H.J.; Mosselman, E.; Sloff, C.J.; Shimizu, Y.","","2013","The paper describes a numerical model for simulating sediment transport with eddy-resolving 3-D models. This sediment model consists of four submodels: pickup, transport over the bed, transport in the water column and deposition, all based on a turbulent flow model using large-eddy simulation. The sediment is considered as uniform rigid spherical particles. This is usually a valid assumption for sand-bed rivers where underwater dune formation is most prominent. Under certain shear stress conditions, these particles are picked up from the bed due to an imbalance of gravity and flow forces. They either roll and slide on the bed in a sheet of sediment or separate from the bed and get suspended in the flow. Sooner or later, the suspended particles settle on the bed again. Each of these steps is modeled separately, yielding a physics-based process model for sediment transport, suitable for the simulation of bed morphodynamics. The sediment model is validated with theoretical findings such as the Rouse profile as well as with empirical relations of sediment bed load and suspended load transport. The current model shows good agreement with these theoretical and empirical relations. Moreover, the saltation mechanism is simulated, and the average saltation length, height, and velocity are found to be in good agreement with experimental results.","river morphodynamics; sediment transport; particles; sediment pickup; saltation; large eddy simulation","en","journal article","American Geophysical Union","","","","","","","2014-02-07","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:9a06cb7d-c6fe-41e1-9e05-63d30bce6dbf","http://resolver.tudelft.nl/uuid:9a06cb7d-c6fe-41e1-9e05-63d30bce6dbf","Morphological modeling using a fully coupled, total variation diminishing upwind-biased centered scheme","Li, W.; De Vriend, H.J.; Wang, Z.; Van Maren, D.S.","","2013","High-resolution morphological modeling of fluvial processes with complex, rapidly varying flows has been limited so far by model accuracy or computational efficiency. One of the most widely used numerical algorithms is based on the total variation diminishing method, solved by either upwind or centered approaches. An upwind scheme preserves high accuracy but is complex and computationally demanding, whereas the simplicity and efficiency of a centered approach compromise the accuracy. The present paper extends a recent upwind-biased centered scheme originally developed for clear water and scalar transport over a rigid bed, to sediment-laden flows over an erodible bed. It does so by developing a fully coupled 2-D mathematical model using a finite volume method for structured grids. The complete set of noncapacity-based governing equations, involving the effects of bed deformation and sediment density variation, as well as the influences of turbulence and sediment diffusion, and the temporal and spatial scales needed for sediment adaptation, is solved at one time to obtain synchronous solutions for the entire computational domain. For stability, a two-stage splitting approach together with a second-order Runge-Kutta method is employed for the source terms. The model is verified in a number of tests covering a wide range of complex (sediment-laden) flows. The model is demonstrated to accurately simulate shock waves and reflection waves, but also rapid bed deformations at high sediment transport rates. The combination of high numerical accuracy and computational efficiency makes the model an important tool to forecast flood events in morphologically complex areas.","morphological modeling; coupled solution; upwind-biased centered scheme; finite volume method; sediment transport; erodible bed; dam break","en","journal article","American Geophysical Union","","","","","","","2013-12-20","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:2b5daf66-7525-4dd7-8a61-2a5ca8a494e9","http://resolver.tudelft.nl/uuid:2b5daf66-7525-4dd7-8a61-2a5ca8a494e9","Modeling Swash zone sediment transport at Truc Vert beach","Van Rooijen, A.; Reniers, A.; Van Thiel de Vries, J.S.M.; Blenkinsopp, C.; McCall, R.","","2012","A one-dimensional hydrostatic version of the XBeach model (Roelvink et al., 2009) is applied to hindcast swash morphodynamics measured during an accretive, and an erosive tide at Le Truc Vert beach (France) in early spring 2008 (Masselink et. al, 2009; Blenkinsopp et al., 2011). Swash hydrodynamics are solved by applying the nonlinear shallow water equations, and sediment transport rates are obtained from a combined intra-wave Nielsen and Bagnold type transport model. Reasonable predictions of morphological change in the swash were obtained. Nevertheless, the model underpredicts the water level setup and/or wave run-up during the accretive tide, which is hypothesized to be related to 2D-effects.","numerical modeling; swash zone; sediment transport; XBeach; bed load; suspended load; le Truc Vert","en","conference paper","Coastal Engineering Research Council","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:d4692a80-8847-47ee-a85d-0da44abeb74e","http://resolver.tudelft.nl/uuid:d4692a80-8847-47ee-a85d-0da44abeb74e","Computational modelling of small-scale river morphodynamics","Nabi, M.","De Vriend, H.J. (promotor); Mosselman, E. (promotor)","2012","Alluvial open channel beds often exhibit statistically periodic irregularities, known as dunes. Dunes have considerable effects on sediment transport and flow resistance. When growing during a flood, the dunes create more resistance and flood levels may rise significantly. Accurate prediction of dune properties therefore contributes to effective flood risk management. Recently, significant progress has been made in understanding bedform dynamics, thanks to significant advances in monitoring flow and bedform morphology in laboratory and field, as well as in their numerical modelling. Nowadays, numerical modelling captures not only the characteristics of the mean flow field, but also those of turbulence, including coherent flow structures above non-flat beds. These advances enable radical progress in modelling and understanding the behaviour of alluvial bedforms. Sediment motion can nowadays be measured and simulated in detail. The effect of turbulent flow on sediment particles can be understood in a more physics-based way. Sediment transport can be linked to bed topography and the bed deformations can be studied by considering the motion of sediment particles in the flow. This gives insight into the evolution and migration of ripples and dunes under turbulent flow and the effects they have on floods. Generation and migration of dunes are determined by sediment transport, which in its turn is influenced by the turbulence structures above and behind the dunes. This kind of physical phenomena involves a wide range of time scales. Often, the measurements cannot capture the smallest time scales, whence many experimental studies consider only statistical properties under homogenous steady-state conditions. Consequently, models based on such measurements can only be empirical. They usually fall short in computing the physical nature of the phenomena in unsteady flows. Therefore, a rigorous physics-based numerical model is needed. This study concentrates on detailed simulations of flow, sediment transport and bedform morphodynamics. Based on these simulations the governing physics behind these phenomena are studied. This is achieved by developing a detailed three-dimensional numerical model for hydrodynamics, sediment transport and morphodynamics. The model simulates the time- dependent water flow by Large Eddy Simulation (LES) on a locally refined Cartesian grid. The sediment is considered as rigid spherical particles moving in the water under gravity and flow-induced forces. The change of bed (morphodynamics) is the net result of pick-up and deposition of sediment on each portion of the bed. The model is validated against theoretical and experimental results of previous studies published in the literature. The resulting model is complex and time-consuming, especially in time-varying flow conditions, such as a flood wave. Therefore, the insights and data obtained with it were used to develop parametric models that can be used operationally at larger spatial and temporal scales. In a number of three-dimensional simulations over two-dimensional bedforms the form drag resulting from the bedforms is compared with existing theoretical, empirical and semi-empirical formulae. It is found that the numerical results agree very well with these formulae. Bedforms in nature, however, are usually three-dimensional. When comparing simulated flows over three-dimensional dunes and with the two-dimensional case, the form drag on three-dimensional dunes turns out to be very different. Based on this finding, the form drag is parameterized for two- and three-dimensional dunes. Furthermore, the generation and migration of dunes under steady flow conditions is studied, and the results are compared with former experimental studies. This comparison shows a very good agreement between the numerical and experimental findings. Dune evolution during floods often shows a hysteresis, with different dune heights at the same discharge during the rising and falling stage of the flood wave. As flow resistance in the main channel of a river is mainly controlled by dune dimensions, the hysteresis in dune height is reflected in the time-evolution of the flow resistance during floods, thus yielding a dynamic roughness. Limited knowledge on this phenomenon, combined with computational limitations, usually keep dynamic roughness behaviour from being included in flood simulation models. To understand the physics behind this hysteresis effect, channels with different discharges and different grain sizes are simulated. It is shown that the hysteresis in the form drag is a function of both variables. Extension of the simulations to the upper flat bed regime shows that the model captures most of the physical phenomena in this regime and yields a flat bed as observed in experiments and in the field.","river morphodynamics; sediment transport; hysteresis; hydrograph; large Eddy simulation; turbulent flow; multigrid; unstructured Cartesian grid; immersed boundaris","en","doctoral thesis","Ipskamp Drukkers B.V.","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:f112b25d-bfc6-4771-8201-2ad5860cf373","http://resolver.tudelft.nl/uuid:f112b25d-bfc6-4771-8201-2ad5860cf373","Macrophytes in estuarine gradients: Flow through flexible vegetation","Dijkstra, J.T.","Stive, M.J.F. (promotor); Uijttewaal, W.S.J. (promotor)","2012","Aquatic plants –or macrophytes- are an important part of coastal, estuarine and freshwater ecosystems worldwide, both from an ecological and an engineering viewpoint. Their meadows provide a wide range of ecosystem services: forming a physical protection of the shoreline, enhancing water quality and harbouring many other organisms. Unfortunately, these vegetations such as salt marshes, seagrasses or mangroves have been on the decline as a result of anthropogenic pressure and climate change, despite costly conservation and restoration efforts. The low success rate of these efforts might partially be due to a lack of understanding of the complex bio-physical interactions between plant properties, plant growth, hydro- and morphodynamics and water quality. The capability of plants to alter their abiotic environment via these interactions is referred to as ‘ecosystem engineering’. Many experimental studies, both in the field and in laboratory flumes, have been performed to unravel these interactions. Since such experiments are always hampered by practical limitations such as flume dimensions, available time, or uncontrolled conditions, this knowledge cannot always be generically applied. Therefore, the primary objective of this study is to develop a generically applicable model for feedbacks between flexible macrophytes and their physical environment. To warrant this general applicability under the various circumstances occurring in estuaries, the model development follows a process based approach; a data-orientated approach is merely applicable to known conditions. Modelling starts out on the scale of one plant to finish at the scale of a meadow. The focus is on seagrass, as seagrasses are well studied, highly flexible, have a relatively simple shape and are among the most productive as well as threatened ecosystems. The first step was to create the numerical model called ‘Dynveg’, by combining a novel dynamic plant bending model based on a Lagrangian force balance to an existing 1DV k-? turbulence model (Chapter 2). The plant bending model is based on measurable biomechanical properties of plants: length, width, thickness, volumetric density and the elasticity modulus. Because very flexible plants can assume a position almost parallel to the flow direction, friction too needed to be incorporated rather than pressure drag alone. Flume measurements on strips of eelgrass-like proportions provided the actual values for drag- and friction coefficients, as well as validation data for predicted strip positions and forces. The effect of multiple plants on hydrodynamics was incorporated by assuming that all plants in a meadow do the same, and by defining two turbulence length scales: One for internally generated turbulence, related to the wakes behind individual stems, and one for larger eddies created in the shear layer above, penetrating the canopy depending on the space between the stems. Dynveg compared favourably with the measurements of hydrodynamic characteristics in mimicked eelgrass by Nepf & Vivoni [2000]. Next, Dynveg was combined with the large-scale hydro- and morphodynamic model Delft3D to simulate two-dimensional spatial processes in and around meadows of flexible macrophytes (Chapter 3). The leading principle for this integration is the conditional similarity between flow characteristics in flexible vegetation and those in rigid vegetation: If the rigid vegetation has i) the same height as the deflected vegetation, ii) its plant volume redistributed over the vertical accordingly and iii) a drag coefficient representative of the streamlined shape, the flow is practically analogous for a range of plant properties and hydrodynamic conditions. This modelling method was validated by comparing model results with flume experiments on two seagrass species, showing good agreement for canopy height, flow velocity profile and flow adaptation length. A field measurement campaign in a French macrotidal bay bordered by an eelgrass meadow provided validation data for application to real meadows (Chapter 5). Along with a detailed bathymetry survey by jetski, time-series of flow velocity and sediment dynamics inside a meadow and over a bare adjacent area were measured over two tidal periods. The applied sediment transport formula [van Rijn, 1993] deals with vegetation effects on sediment pick-up and transport via the effects of plants on hydrodynamics. Vegetation-specific interactions such as particle trapping by blades or flow intensification directly around shoots were not taken into account. Nevertheless, the three-dimensional numerical model was able to reproduce the main features of the observations, indicating that the processes of vegetation bending in non-stationary flow and sediment transport through vegetated areas are incorporated correctly. Thus, the objective of making a model for feedbacks between flexible macrophytes and their physical environment has been met. The model can be applied as a tool in conservation and restoration studies or in long-term biogeomorphological feedback studies. Recommended extensions are the incorporation of plant-wave interactions, more intricate plant morphologies and a vegetation-specific transport formula. The second objective of this thesis was to use the developed model(s) as a tool to learn more about biophysical interactions under different conditions. In Chapter 4, Dynveg and the two-dimensional model were used to assess the ecosystem engineering capacities of three plant species that partly co-occur in temperate intertidal areas: the stiff Spartina anglica, the short flexible seagrass Zostera noltii and the tall flexible seagrass Zostera marina. The flow velocity inside the canopy, the canopy flux and the bed shear stress were used as proxies for the species’ ability to respectively absorb hydrodynamic energy, the supply of nutrients or sediment and the ability to prevent erosion. This analysis showed that a species’ eco-engineering capacities depend on its spatial density, its size, its structural rigidity and its buoyancy, but also on environmental conditions. Therefore, biomass, leaf area index or other lumped parameters that neglect structural properties are no good generic indicators of ecosystem engineering capacities. Rigid plants have more potential to trap sediment due to a higher canopy flux than flexible plants. This canopy flux showed to be inversely related to spatial density along the entire natural range. For flexible plants, the canopy flux is only related to density in relatively sparse meadows; in denser meadows the canopy flux is constant with increasing density. Flexible plants are better at preventing erosion because they are more efficient in reducing bed shear stresses than rigid plants. For very thin plants, buoyancy is the most important determinant of position in given flow conditions. For intermediate flexible plants, the structural rigidity is the most influential parameter, whereas for (nearly) rigid plants, the spatial density is dominant. In Chapter 6, the three-dimensional model of the macrotidal bay was used to study the effects of different types of macrophytes on (residual) sediment transport and light availability. The effects of the real, relatively sparse eelgrass meadow were compared to those of a meadow with rigid plants of the same spatial density, with a dense eelgrass meadow, and with a bare bed. Though the differences between these four vegetation scenarios were small –only a few percent- the consequences on long timescales can be considerable. In deep water, sparse flexible vegetation kept more sediment inside the bay than rigid or denser plants. When vegetation only occupies a small part of the water column, plants prevent erosion rather than promote deposition and they have more effect on bed-load transport than on the transport of suspended sediment. Stiff and denser plants affect the bed-load more than sparse flexible vegetation, thereby blocking the transport from outside to inside. The presence of dense or stiff macrophytes increased the light availability at the bed over a tidal cycle up to 7% with respect to a bare bed. The increase of light availability was less pronounced for the relatively open eelgrass meadow: up to 3%. Overall, this study has resulted in a widely applicable model for the interactions between flexible aquatic plants, flow and sediment transport and in more insight in some of these interactions. Other researchers are encouraged to use this tool complementary to fieldwork and laboratory experiments, and to extend it with other functionalities, e.g. for wave attenuation or vegetation development.","macrophyte; flexible vegetation; estuary; hydrodynamics; turbulence; ecology; sediment transport; light climate; seagrass","en","doctoral thesis","","","","","","","","2012-03-06","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:3fa8d72d-c3aa-4786-a321-41433ad1df78","http://resolver.tudelft.nl/uuid:3fa8d72d-c3aa-4786-a321-41433ad1df78","Transport of suspended particles in turbulent open channel flows","Breugem, W.A.","Uijttewaal, W.S.J. (promotor); Stelling, G.S. (promotor)","2012","Two experiments are performed in order to investigate suspended sediment transport in a turbulent open channel flow. The first experiment used particle image velocimetry (PIV) to measure the fluid velocity with a high spatial resolution, while particle tracking velocimetry (PTV) was used to measure the velocity of individual sediment particles. The sediment particles were injected in the flume close to the free surface at different distances from the measurement section. In this way, the development of a sediment plume towards an equilibrium situation could be studied. The results were compared with direct numerical simulations, in which the particle equation of motion was used to calculate the movement of individual sediment particles. The second experiment used refractive index matching, in order to make the sediment particle invisible. In this way, a PIV experiment could be performed in order to determine changes in the flow and turbulence structure due to high sediment concentrations.","sediment transport; PIV; PTV; refractive index matching; coherent structures; turbulence; DNS; two way coupling","en","doctoral thesis","","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:d9b27e21-5cc0-41e8-a6bc-c6e9d4e6d103","http://resolver.tudelft.nl/uuid:d9b27e21-5cc0-41e8-a6bc-c6e9d4e6d103","DVR toolbox for sediment management in the Rhine delta","Sloff, C.J.","","2011","The DVR Toolbox is a modeling system developed to be used as an operational model for long-term morphological assessment of the Rhine branches in the Netherlands (10 to 50 years). The Toolbox consists of a 2D computational core (containing the Delft3D modeling system), a shell that controls input- and output, and a system for time/simulation management. The effects of different processes, e.g. helical flow and sediment sorting, on time-dependent bed topography and dredging-operations can be simulated. It has been designed and optimized to allow for relative short computation times: 40 year simulations for the full delta can be run in less than 1 week. The Toolbox is mostly used to calculate morphological impacts that affect the navigability of the Rhine, and the impact of measures to affect them. It is now also widely used as an official tool to study the impacts of flood-lowering measures in the Room for the River program. Also for future studies in the Rhine River this Toolbox will be widely used.","sediment transport; Rhine river; Delft 3D","en","conference paper","Rheinisch-Wesfälische Technische Hochschule (RWTH) Aachen","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:db31899c-ca91-47a1-879e-4f4fa1d004e8","http://resolver.tudelft.nl/uuid:db31899c-ca91-47a1-879e-4f4fa1d004e8","A process-based approach to sediment transport in the Yangtze estuary","Chu, A.; Wang, Z.B.; De Vriend, H.J.; Stive, M.J.F.","","2010","A process-based model for the Yangtze Estuary is constructed to study the sediment transport in the estuary. The proposed model covers the entire tidal region of the estuary, the Hangzhou Bay and a large part of the adjacent sea. The dominant processes, fluvial and tidal, are included in the model. The calibration of the model against extensive flow, water level, salinity and suspended sediment data shows a good representation of observed phenomena. With the present calibrated and validated model, the residual flow field and the residual sediment transport field are obtained. The residual sediment transport pattern gives insight into the morphological behaviour of the mouth bars.","Yangtze Estuary; mouth bar; morphology; sediment transport; process-based model","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:677a707f-7554-4db5-9139-9f1e9d1d25ef","http://resolver.tudelft.nl/uuid:677a707f-7554-4db5-9139-9f1e9d1d25ef","Heavy metal pollution and sediment transport in the rhinemeuse estuary, using a 2D model Delft3D: Water quality and calamities. Case study Biesbosch","Jose Alonso, J.J.","","2010","Different measures will be executed in the framework PKB “Room for the River” in order to lower the water levels in the river area during normative high discharges. The plan Ontpoldering Noordwaard is one of them and has as aim to inundate parts of the Noordwaard during high discharges. Water coming from the Nieuwe Merwede as result of high water levels will flow into the Noordwaard and leave the area through the south part. As consequence the creeks in the Brabantse Biesbosch will process more water and flow velocities will increase. This may result in higher sediment transport en possible erosion of the gullies. Dankers et al. (2008) studied the flow velocities in the Brabantse Biesbosch under different discharge conditions and the possible effects of the velocities on erosion and transport of contaminated bed material. This study was a combination of computer model simulations and expert judgment. The model simulations were obtained with the combination of boundary conditions for discharges with a return period of once in 100 year for the Rhine and Meuse and a water level of the sea of 1 m above normal. In this case flow velocities higher than 1 m/s and shear stresses higher than 1 N/m2 were found at different locations of the Brabantse Biesbosch. This means that a transition may occur from a situation without spreading of contaminated bed material towards a situation where spreading can occur. By comparing the quality of the top layer of the areas with risk of erosion according to De Straat (2004) with the intervention values for river beds (“Circulaire Sanering Waterbodems 2008”) and the MACsediment (Maximum Allowed Concentration in the Sediment), Dankers et al. (2008) found that different areas in the Brabantse Biesbosch may exceed the intervention values and/or the MAC for sediments. The areas Gat van de Visschen, Gat van Den Kleine Hil and Gat van de Noorderklip present concentrations of metals in the top layer that are higher than the intervention values and the MAC. In the areas Gat van Van Kampen, Gat van de Binnennieuwensteek and Spijkerboor a small violation of the MACsediment was observed. This study concluded that there are unacceptable risks of spreading of contaminated mud to the surface water.","heavy metal; pollution; sediment transport; rhine; meuse; 2D model; Delft3D; water quality and calamities; case study; Biesbosch; river; room for the river; ontpoldering Noordwaard; high water levels; serosion; computer model simulations; Delft Cluster; CT04.20; waterkwaliteit; CT04.24.11; risicomanagement van calamiteiten; waterquality","en","report","Delft Cluster","","","","","","","","","","","","","" "uuid:76b7747c-5b46-49a3-8cb1-1881f388718a","http://resolver.tudelft.nl/uuid:76b7747c-5b46-49a3-8cb1-1881f388718a","Effect of bottom stress formulation on modelled flow and turbidity maxima in cross-sections of tide-dominated estuaries","Schramkowski, G.P.; De Swart, H.E.; Schuttelaars, H.M.","","2009","A three-dimensional numerical model with a prognostic salinity field is used to investigate the effect of a partial slip bottom boundary condition on lateral flow and sediment distribution in a transect of a tidally dominated channel. The transect has a symmetrical Gaussian cross-channel bottom profile. For a deep, well-mixed, tidally dominated channel, partial slip decreases the relative importance of Coriolis deflection on the generation of cross-channel flow patterns. This has profound implications for the lateral distribution of residual salinity that drives the cross-channel residual circulation pattern. Transverse sediment transport, however, is always found to be governed by a balance between advection of residual sediment concentration by residual lateral flow on the one hand and cross-channel diffusion on the other hand. Hence, the changes in the cross-channel distribution of residual salinity modify the lateral sediment distribution. For no slip, a single turbidity maximum occurs. In contrast, partial slip gives a gradual transition to a symmetrical density distribution with a turbidity maximum near each bank. For a more shallow, partially mixed tidal channel that represents the James River, a single turbidity maximum at the left bank is found irrespective of the near-bed slip condition. In this case, semi-diurnal contributions to sediment distribution and lateral flow play an important role in cross-channel sediment transport. As vertical viscosity and diffusivity are increased, a second maximum at the right bank again exists for partial slip.","turbidity; estuary; sediment transport; morphodynamic equilibrium","en","journal article","Springer","","","","","","","","Electrical Engineering, Mathematics and Computer Science","Delft Institute of Applied Mathematics","","","","" "uuid:62e2183b-3dcc-489c-8020-56a250febe77","http://resolver.tudelft.nl/uuid:62e2183b-3dcc-489c-8020-56a250febe77","Modeling equilibrium bed profiles of short tidal embayments: On the effect of the vertical distribution of suspended sediment and the influence of the boundary conditions","Ter Brake, M.C.; Schuttelaars, H.M.","","2009","In many tidal embayments, bottom patterns, such as the channel-shoal systems of the Wadden Sea, are observed. To gain understanding of the mechanisms that result in these bottom patterns, an idealized model is developed and analyzed for short tidal embayments. In this model, the water motion is described by the depth- and width-averaged shallow water equations and forced by a prescribed sea surface elevation at the entrance of the embayment. The bed evolves due to the divergence and convergence of suspended sediment fluxes. To model this suspended-load sediment transport, the three-dimensional advection–diffusion equation is integrated over depth and averaged over the width. One of the sediment fluxes in the resulting one-dimensional advection–diffusion equation is proportional to the gradient of the local water depth. In most models, this topographically induced flux is not present. Using standard continuation techniques, morphodynamic equilibria are obtained for different parameter values and forcing conditions. The bathymetry of the resulting equilibrium bed profiles and their dependency on parameters, such as the phase difference between the externally prescribed M2 and M4 tide and the sediment fall velocity, are explained physically With this model, it is then shown that for embayments that are dominated by a net import of sediment, morphodynamic equilibria only exist up to a maximum embayment length. Furthermore, the sensitivity of the model to different morphological boundary conditions at the entrance of the embayment is investigated and it is demonstrated how this strongly influences the shape and number of possible equilibrium bottom profiles. This paper ends with a comparison between the developed model and field data for the Wadden Sea’s Ameland and Frisian inlets. When the model is forced with the observed M2 and M4 tidal constituents, morphodynamic equilibria can be found with embayment lengths similar to those observed in these inlets. However, this is only possible when the topographically induced suspended sediment flux is included. Without this flux, the maximum embayment length for which morphodynamic equilibria can be found is approximately a third of the observed length. The sensitivity of the model to the topographically induced sediment flux is discussed in detail.","tidal basin; estuary; idealized model; morphodynamic equilibrium; sediment transport; boundary condition","en","journal article","Springer","","","","","","","","Electrical Engineering, Mathematics and Computer Science","Delft Institute of Applied Mathematics","","","","" "uuid:fcb49e4d-b0e0-45a4-9d67-be7ec4430ffd","http://resolver.tudelft.nl/uuid:fcb49e4d-b0e0-45a4-9d67-be7ec4430ffd","A Hybrid Approach to Combine Physically Based and Data-Driven Models in Simulating Sediment Transportation","Sewagudde, S.","","2008","The objective of this study is to develop a methodology for hybrid modelling of sedimentation in a coastal basin or large shallow lake where physically based and data driven approaches are combined. This research was broken down into three blocks. The first block explores the possibility of approximating a physically based model using a data driven model to predict suspended particulate matter (SPM) concentrations. It identifies the necessary input variables and data manipulation operations to expose maximum information to a data driven modelling tool. The second block investigates the effect of specifying time varying open boundary condition instead of fixed boundary conditions on the simulation of (SPM) along the Dutch coast. First, a methodology for generating time varying open boundary conditions using a data driven model is developed. Local hydrodynamic and meteorological conditions are used as input variables. Secondly the improvement of the time varying open boundary conditions (OBC) on the simulation results is studied The third block examines how knowledge gained in modelling sediment transport along the Dutch coast can be transfer to understand sediment transport in Lake Victoria. This part lays ground for more accurate and reliable modelling of sediment transport in Lake Victoria in future through transfer of methods developed in the preceding sections.","hybrid approach; physically based; data driven; simulating sediment transportation; hybrid modelling; sedimentation; coastal basin; shallow lake; model; suspended particulate matter; SPM; simulation; Dutch coast; hydrodynamic; meteorological; open boundary conditions; OBC; sediment transport; Lake Victoria; North sea; Delft Cluster; CT05.20; Noordzee & kust; CT05.24.11; morfodynamiek van Noordzee en kust en kustverdediging","en","report","Delft Cluster","","","","","","","","","","","","","" "uuid:cd32f46a-607d-437b-a748-810f87b46533","http://resolver.tudelft.nl/uuid:cd32f46a-607d-437b-a748-810f87b46533","The effect of sediment transport on eelgrass development – and vice versa","Dijkstra, J.T.","","2007","By changing flow patterns and sediment transport, aquatic vegetation can affect the development of estuarine bed topography. Besides, since the sediment transport also determines the amount of light available for photosynthetic growth, the presence of vegetation can also affect its own development. This selfsupporting interaction should be taken into account in long-term modelling studies. A process-based model offers the possibility to study this interaction and improve the predictability of eelgrass restoration attempts.","vegetation; photosynthesis; seagrass; sediment transport","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:43dae97c-431c-4ed3-8064-35686940a32a","http://resolver.tudelft.nl/uuid:43dae97c-431c-4ed3-8064-35686940a32a","Transport modelling in coastal waters using stochastic differential equations","Charles, W.M.","Heemink, A.W. (promotor)","2007","In this thesis, the particle model that takes into account the short term correlation behaviour of pollutants dispersion has been developed. An efficient particle model for sediment transport has been developed. We have modified the existing particle model by adding extra equations for the suspension using a probabilistic concepts (the Poisson distribution function) to determine the actual number of particles to suspend in each cell. The deposition is modelled by an exponential decaying ordinary differential equation. In order to get accurate results from Monte Carlo simulations of sediment transport, a large number of particles is often needed. However, computation time in a particle model increases linearly with the number of particles. Thus, we have developed a high performance particle model for sediment transport by considering three different sediment suspension methods. Parallel simulation experiments are performed in order to investigate the efficiency of these three methods. We conclude that the second method is the best method on distributed computing systems (e.g., a Beowulf cluster), whereas the third maintains the best load distribution. Using variable time stepping to integrate the particle track in this thesis, has also proved to be efficient.","Wiener process; dispersion coefficient; coloured noise forces; stochastic differential equation; lagrangian particle model; pollution; sediment transport; parallel processing; speed up; load balance; efficiency","en","doctoral thesis","","","","","","","","","Electrical Engineering, Mathematics and Computer Science","","","","","" "uuid:dd582270-dc42-4219-a404-a93d22c02367","http://resolver.tudelft.nl/uuid:dd582270-dc42-4219-a404-a93d22c02367","Morphodynamic instabilities of planar beaches: Sensitivity to parameter values and process formulations","Klein, M.D.; Schuttelaars, H.M.","","2005","The initial growth of bed perturbations on planar sloping beaches under the forcing of obliquely incident, breaking waves is investigated using a state?of?the?art numerical model. This allows for a systematic investigation of the sensitivity of the spatial structures of the bed perturbations and their growth and migration rates to different model formulations and parameterizations. If the sediment is only transported in the direction of the net current velocity and sediment stirring is taken proportional to the wave height squared, growing up?current oriented crescentic bars are found with a preferred spacing of 800 m and a down?current migration rate of 10 m d?1. Varying the angle of wave incidence, drag coefficient and bed slope results in qualitatively similar growing bed forms. Using an Engelund and Hansen transport formula, very oblique down?current oriented bars are obtained that grow in time. No preferred wavelength, however, is found. Using the Bailard transport formula results in growing, up?current oriented bars with a preferred spacing smaller than 300 m for wave angles smaller than 7°. When using either the Engelund and Hansen or Bailard sediment transport formulation, it is essential to take the transport in the direction of the wave orbital velocity into account in order to have growing bed perturbations.","linear stability analysis; planar beaches; sediment transport","en","journal article","American Geophysical Union","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:3c9b630e-37ef-4c49-9a3f-a4a471353c85","http://resolver.tudelft.nl/uuid:3c9b630e-37ef-4c49-9a3f-a4a471353c85","Analytic solutions for flow in tidal inlets with tributary inflow","Lam, N.T.; Verhagen, H.J.; Van der Wegen, M.","","2004","Hydraulic characteristics of flow in a tidal inlet act an important role in morphological changes of the inlet. In normal conditions, inlet currents flush sediment out of the inlet to maintain its opening against longshore sediment transports that tend to close the inlet. The currents in the inlet are contributed by the tides and also from upstream river inflows as can be seen in many tidal inlets in tropical areas. Stability analysis for those tidal inlets can be done based on analytic solutions of inlet hydraulics. This paper presents a new analytic solution of tidal inlet hydraulics with inertia term and contribution of tributary inflow. The solution is compared with other studies. Based on the analytic solution, stability analysis for tidal inlets can be carried out.","tidal inlet; tidal lagoon; sediment transport","","journal article","WRU- Hanoi","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:1107be41-27fb-430c-a63c-09fe839fc928","http://resolver.tudelft.nl/uuid:1107be41-27fb-430c-a63c-09fe839fc928","Sediment exchange between the main channel and the groyne fields of a river","Yossef, M.F.M.","","2003","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.","groynes; rivers; river morphology; sediment transport; Delft Cluster; DC 03.03.04","en","report","Delft Cluster","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:5cf30bdd-d81f-438d-86ec-bcddb1fa1b07","http://resolver.tudelft.nl/uuid:5cf30bdd-d81f-438d-86ec-bcddb1fa1b07","Ontmenging van granulaire materialen bij toepassingen in waterbouwkundige constructies: Voorspelling en beoordeling van ontmengingsinvloeden in praktijksituaties","Vrijling, J.K.; Hauer, M.; Van der Meulen, T.","","1998","Het verschijnsel ontmenging is al sinds lang een bekend fenomeen bij ontwerpers en constructeurs van granuiaire constructies. Desalniettemin is nog altijd erg weinig bekend over de aard en de omvang van de gevolgen die het optreden van dit verschijnsel voor het functioneren van een constructie kan hebben. Tot op heden bleven de beschouwingen over ontmenging beperkt tot hoofdzakelijk kwalitatieve beschouwingen, waaruit voor de Nederlandse bouwwereld enkele praktische richtlijnen voor de uitvoering van granuiaire constructies voortkwamen. Numerieke schattingen voor effecten van ontmenging ontbreken echter. Deze studie is geschreven als eerste stap op weg naar een situatie waarin dergelijke numerieke schattingen wel tot de mogelijkheden zullen gaan behoren. Daarbij is ook aandacht besteed aan de mogelijke gevolgen van de effecten van ontmenging voor het functioneren van granuiaire constructies. Aangezien allereerst nog een goede, kwantificeerbare definitie van het verschijnsel ontmenging ontbrak is begonnen met de opstelling van een dergelijke definitie. Het verschijnsel ontmenging is in deze studie op zodanige wijze omschreven dat men met behulp van deze definitie tijdens een analyse van steekproefresultaten van meerdere monsters uit één partij stenen altijd binnen een zekere nauwkeurigheid kan vaststellen of in die partij wel of geen ontmenging is opgetreden. De niet door ontmenging veroorzaakte toevalsgebonden fluctuaties in kentallen worden daarbij als maatstaf gebruikt.","ontmenging; korrels; granulair materiaal; filters; sediment transport","nl","report","TU Delft, sectie waterbouw","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:759597b8-ed4c-435b-97f3-3ac7a17859c0","http://resolver.tudelft.nl/uuid:759597b8-ed4c-435b-97f3-3ac7a17859c0","Erosie onder een geometrisch open filter","Booij, R.","","1998","Deze notitie beschrijft de resultaten van een inleidend onderzoek naar de mechanismen van de erosie van de basislaag onder geometrisch open filters. Hierbij wordt in eerste instantie uitgegaan van de beter onderzochte erosie van de bodem van een waterloop zonder beschermende filterlaag. Op basis van metingen van Van Os (1998) in een inleidend onderzoek wordt daama de stroming in een filterlaag geanalyseerd. De stroming tussen de filterelementen blijkt qua karakter sterk te verschillen van de strorning in de waterloop. Gemiddelde snelheid en schuifspanning zijn gering. Bij de relatief sterke fluctuaties van de snelheid kunnen twee duidelijk verschillende schalen onderscheiden worden: kortdurende fluctuaties die te maken hebben met de turbulentie in de porien tussen de filterelementen en langdurende fluctuaties die lijken samen te hangen met de grootschalige turbulenties in de waterloop. Gebaseerd op de analyse van de metingen in de filterlaag is het volgende beeld van het mechanisme van de erosie van de basislaag onder een filter ontwikkeld. Drukkrachten samenhangend met de kortdurende fluctuaties maken de zandkorrels los uit de basislaag en de langdurende fluctuaties zorgen voor het transport van de zandkorre1s over de filterlaag. Aangetoond wordt dat in elk geval bij de besproken metingen dit laatste transport bepalend is voor de uiteindelijke erosie van de basislaag. Op grond van het geschetste model van de erosie onder filters lijkt het goed mogelijk tot ontwerpregels voor verschillende soorten waterlopen en stromingssituaties te komen. Een schatting geeft aan dat deze erosie de toepasbaarheid van de gebruikelijke geometrisch open filters beperkt. Om de vele vragen en onzekerheden die op grond van deze uitwerking van het inleidend onderzoek van Van Os kunnen worden geformuleerd op te lossen is aanvullend onderzoek nodig. Hiervoor worden suggesties gedaan.","erosion; filter; geometrically open filter; sediment transport","nl","report","TU Delft","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:0d091907-22d3-41d2-b08d-56073ac6ae17","http://resolver.tudelft.nl/uuid:0d091907-22d3-41d2-b08d-56073ac6ae17","Modeling Shoreface Profile Evolution","Stive, M.J.F.; De Vriend, H.J.","","1995","","evolution; sea-level rise; sediment transport; beach equilibrium","en","journal article","","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:a7275bc5-566f-4121-b6ef-9c898b578fef","http://resolver.tudelft.nl/uuid:a7275bc5-566f-4121-b6ef-9c898b578fef","Sand transport in oscillatory sheet-flow; a literature review","Janssen, C.M.","","1995","This literature review is part of the ongoing research on sand transport in oscillatory sheet-flow, as taking place at the coast during storms. Because sheet-flow corresponds to conditions of high shear stress, large amounts of sand are transported. Therefore it is an important part of the total sand transport (sheet-flow and suspended load). Sand transport is a very important phenomenon in almost all coastal engineering problems. When a harbour is to be developed it is important to know how much sand is transported and in what direction, in order to prevent sedimentation problems in the entrance channel or in the harbour itself. Another example deals with coastal defence measures to prevent erosion of a beach. Either the use of coastal structures, like breakwaters, groynes etc., or a beach nourishment scheme requires information about the magnitude and direction of the general and local sand transport. Unlike the sand transport in rivers, which can be assumed to occur in a merely one- dimensional, steady uniform flow, the sand transport at the coast is the result of a complex interaction of steady currents and a wave-induced unsteady oscillatory flow at an arbitrary angle to the current. In order to predict the resulting sand transport, many different models have been developed. The aim of this literature study is to present an overview of the models, that predict the unsteady sand transport in sheet-flow conditions. Some of the models are specifically derived for sand transport under sheet-flow conditions, while others have a more general basis. A comparison is made between the capability of the different existing models in predicting the sand transport in sheet-flow conditions. Moreover also the different experimental studies on sand transport in oscillatory flow are presented. As a result of the comparison the most encouraging direction for the ongoing research is determined.","sediment transport; waves","en","report","TU Delft","","","","","","","","Civil Engineering and Geosciences","","","","","" "uuid:4c00f467-0997-4361-a724-cab28d4ac01d","http://resolver.tudelft.nl/uuid:4c00f467-0997-4361-a724-cab28d4ac01d","Technical note for sediment transport rate: Analysis of delta flume data and calculations","Zhang, C.K.","","1994","Data analysis of Delta flume observations and calculationsThe objective of the present study is to analyse the measurement data of profiles and velocity moments, to derive the measured cross-shore sediment transport rates from the profile records and to compare the observed transport rates with the results from several existing prediction models of cross-shore sediment transport. This report is a summary of preliminary analysis and calculations of 2 tests with test number 2A and 2B. The report includes profile analysis, the derivation of measured transport rates, the computations of cross-shore transport rate by Bailard's formula and t h e comparison between the measured and the computed results.","sediment transport; waves; cross-shore transport","en","report","","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:52da5065-10a7-4d5a-ad77-15f1ed462c1d","http://resolver.tudelft.nl/uuid:52da5065-10a7-4d5a-ad77-15f1ed462c1d","Cross-shore sediment transport; analysis of Delta Flume data and mathematical modelling","Zhang, C.","","1994","In the last decade, several mathematical models for cross-shore sediment transport have been developed under the assumption that the instantaneous sediment transport is directly related to the instantaneous horizontal velocity just above the boundary layer. Although some models took beach slopes into account, most of the calibrated data were from flat-bed experiments, and most experiments were carried out on a rather small scale. Under the framework of the European Large Installation Plan, to achieve high quality and high resolution data on hydrodynamics and sediment transport dynamics on a natural 2DV beach under equilibrium, erosive and accretive conditions, a programme of detailed measurements of hydrodynamics and sediment transport in the surf zone has been carried out in DELFT HYDRAULICS' Delta Flume in the period from April to June 1993 (DELFT HYDRAULICS 1994). Hence a set of new data about beach evolution and acting velocity moments has become available. The objectives of the present study are: (1) to derive the measured crossshore sediment transport rates from the profile measurements, (2) to predict cross-shore sediment transport rates from measured velocity moments by using several existing mathematical models, (3) to compare the results between measured and computed data and [ if (3) yields a poor comparison ] (4) to propose a modified model. This report is a summary of the work. The report includes profile analysis, the derivation of measured transport rates, the computations of cross-shore transport rates by three selected prediction models and the comparison between measured data and computed results as well as the calibration and verification of the proposed model.","sediment transport; dune erosion","en","report","TU Delft","","","","","","","","Civil Engineering and Geosciences","","","","","" "uuid:61147e1f-effd-408c-a9d6-6ea4c7e7ebef","http://resolver.tudelft.nl/uuid:61147e1f-effd-408c-a9d6-6ea4c7e7ebef","In search of a better sediment mixing coefficient model","Voorendt, M.; Van de Graaf, J.","","1994","Results of sediment transport calculations are often necessary in solving practical coastal engineering problems. (Sediment transport due to waves and currents). Many transport formulae have been proposed in literature in the past. Selection of the proper one while solving a particular problem, is a difficult task for a coastal engineer. In considering sediment transport under wave-current conditions it is worthwhile to make a distinction between two situations, viz.: The fluctuations in the orbital motion have to be fully taken into account in order to find the resulting sediment transport (intra-wave type of description; often: cross-shore sediment transport); - It is sufficient to take time-averaged effects of the waves into account in order to find the resulting sediment transport rate (intra-wave type of description is not required; often: longshore sediment transport). For the longshore sediment transport mode, transport formulae based on time-averaged velocity distributions and time-averaged sediment concentration distributions over the water depth can often be used. The present paper is restricted to this type of formula.","sediment transport; mixing coefficient","en","report","TU Delft","","","","","","","","Civil Engineering and Geosciences","","","","","" "uuid:eccee569-9391-48e4-a550-06ffae10de39","http://resolver.tudelft.nl/uuid:eccee569-9391-48e4-a550-06ffae10de39","Analysis of basic equations for sediment-laden flows","Sloff, C.J.","","1993","Derivations and analyses of basic equations for I-dimensional sediment-laden flow (concentrations up to about 10% of volume) on a mobile bed are presented . Equations of mass and momentum conservation have been derived by means of a control section as well as by depth integration. Therefore a three-layer approach has been used (i.e., bed layer, bed-load layer, and suspended-load layer). Despite the assumptions of uniform sediment, fixed banks and constant width the derivations can easily be extended for more general models. Analysis of the basic equations b means of the method of characteristics showed that with increasing concentration wave celerities alter, and showed that critical flow occurs at Froude numbers less than unity. A stability analysis of the equations showed that the criterion for occurrence of roll waves in supercritical flow is also modified by the increased concentration. Due to increased concentrations roll waves can occur in sediment-laden flow at lower Froude numbers than in clear water flow.","sediment transport","en","report","TU Delft","","","","","","","","Civil Engineering and Geosciences","","","","","" "uuid:2ec6784e-288e-4d87-b7d0-56a9223ebee1","http://resolver.tudelft.nl/uuid:2ec6784e-288e-4d87-b7d0-56a9223ebee1","An entrainment model for fluid mud","Kranenburg, C.","","1993","An entrainment model for fluid mud is derived by integrating the equation for turbulent kinetic energy across the mixed layer and introducing some modelling assumptions. The resulting entrainment model is similar to models of mixed-layer deepening in lakes and reservoirs, but in addition accounts for the work needed to entrain bed material. Two basically different flow conditions are considered: (1) flow in the water layer but no flow in the fluid-mud layer, and (2) flow in both layers driven by a tide-induced streamwise pressure gradient. In the first case, which applies to laboratory experiments in an annular flume, for example, the water layer is the turbulent mixed layer that erodes the quiescent fluid-mud layer. In the second case the fluid-mud layer is the mixed layer, which deepens because of entrainment of water from the overlying water layer. The water layer then is the quiescent layer. The viscous drag of the quiescent layer due to the flow in the mixed layer, which effect can play a part in laboratory experiments, is accounted for. Empirical model coefficients are obtained from the literature.","sediment transport; mud","en","report","TU Delft","","","","","","","","Civil Engineering and Geosciences","","","","","" "uuid:8f759809-4a01-4407-bad3-d1f63b081a04","http://resolver.tudelft.nl/uuid:8f759809-4a01-4407-bad3-d1f63b081a04","Bed-levelling experiments with suspended load","Talmon, A.M.; De Graaff, J.","","1991","Bed-levelling experiments are conducted in a straight laboratory channel. The experiments involve a significant fraction of suspended sediment transport. The purpose of the experiments is to provide data for modelling of the direction of sediment transport on a transverse sloping alluvial river bed, specifically in presence of suspended sediment transport. The transverse slope parameter for these experiments is determined.","suspended load; experiments; bed-levelling; suspended sediment; morphology; sediment transport; transverse slope","en","report","TU Delft, Department of Hydraulic Engineering","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:755509c5-6453-4a63-a397-e6faf60f272f","http://resolver.tudelft.nl/uuid:755509c5-6453-4a63-a397-e6faf60f272f","Laboratory observations of the velocity field in the entrance of a tidal harbor and the exchange of heat between harbor and river","Langendoen, E.J.","","1990","The research that has been presented in this report is a part of an ongoing study on the siltation of tidal harbors. The study deals with the water motion in the harbor entrance, which motion causes the siltation. As yet, too little is known about this complicated time-dependent water motion. The data obtained during the research will be used to calibrate the 3-D numerical model Trisula, so that this model can be used as a tool to predict the water motion in a harbor entrance. With the present knowledge of the transport of cohesive sediments, a better prediction of the siltation of a particular harbor entrance will then be possible. Experiments have been performed in a physical model at the Laboratory of Fluid Mechanics of the Delft University of Technology. In these experiments the influences, on the flow patterns in the harbor entrance and the exchange of heat between harbor and river, of the geometries of the harbor and the harbor entrance, the tidal period and tidal water level changes were examined. Measurements of the time-dependent velocity and temperature fields were made in five model harbors. In the experiments without tidal water level changes three harbors had their length axes perpendicular to the length axis of the river, namely (1) a square harbor of 1 m2, (2) a rectangular harbor of 1 x 2 m2 and (3) a square harbor of 1 m2 with a narrowed entrance of 0.5 m; one harbor, (4), of 1 m2 and an entrance width of 1 m had its length axis at an angle of 45 degrees to the length axis of the flume. In the experiment with tidal water level changes a rectangular harbor, (5), with an entrance width of 1 m and a storage area of 8 m2 had its length axis perpendicular to the length axis of the river. It can be concluded that: details of circulating flows and gyres depend markedly on the geometry of the harbor. the progress of the phenomena after slack water in model harbor (2), that is the development of a new primary gyre, does not seem to depend on the tidal period. As a consequence, the phase difference between the development of the gyre and the accelerating flow in the river increases as the period decreases. the flow pattern in the harbor is highly influenced by the orientation of the harbor entrance. An explanation for this phenomenon is deficient at the moment. in the model harbors, except harbor (3), a quite strong secondary current is present in the gyre. The maximum velocity in the secondary current is on the average 15 per cent of the main flow. This means that a three-dimensional numerical model will be necessary to simulate the flow pattern in the harbor correctly. close to the downstream sidewall, in all model harbors, larger water velocities (20 to 50 per cent larger) were observed near the bottom than higher in the water column. Near the bed high-momentum fluid from the mixing layer between harbor and river appears to be transported into the harbor. tidal water level changes cause an acceleration in the development of the new gyre towards high tide. Towards low tide the development of the new gyre is hindered by the emptying of the basin. in harbors (1), (2) and (4) a large increase in advective exchange takes place around slack water. The influence of turbulence seems to be of secondary importance during this phase of the tide. a narrowed entrance highly reduces the exchange of mass between harbor and river at slackwater. if the flow pattern in the harbor comprises various gyres, in this research harbor (2), the normalized exchange will be less because the secondary,tertiary, etc. gyres do not contribute to the exchange process. wgen the current in the river is around maximum,the flow is quasi-steady for a quite large duration. The exchange then takes place through the mixing layer between river and harbor, that is, it is caused by turbulent motions only. although during slack water a less refined turbulence model is sufficient in a numerical model, the modeling of turbulence is important during the quasi-steady phase of the tide, especially when the geometry of the entrance is more complex (e.g. harbor (4)).","siltation; tidal harbor; water motion; sediment transport; harbor entrance; velocity field; laboratory observations","en","report","TU Delft, Department of Hydraulic Engineering","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:2dbed657-4801-4c34-a139-7d9d95ae6583","http://resolver.tudelft.nl/uuid:2dbed657-4801-4c34-a139-7d9d95ae6583","Suspended-load experiments in a curved flume, run no. 3","Talmon, A.M.; De Graaff, J.","","1989","A laboratory experiment in a 180 degree curved flume with a mobile bed and suspended sediment transport is described. The flow is steady. The bed topography is measured by means of a profile indicator. The bed topography is characterized by a slowly damped oscillation of the transverse bed slope. Downstream of the bend entrance a pool and a submerged point-bar are present, here the radial bed slope is maximal. Further downstream the transverse bed slope decreases and subsequently increases again. No axi-symmetrical part is present. The bed topography is very similar to the topography of an earlier experiment. Suspended sediment concentrations are determined by the method of siphoning and by optical measurement. Concentration verticals are measured throughout the whole bend (at 1/4, 1/2 and 3/4 of the channel width). At one specific location a denser measuring grid is used.","suspended-load; experiments; curved flume; morphology; bed topography; suspended sediment; sediment transport","en","report","TU Delft, Department of Hydraulic Engineering","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:b6eda6ca-cab6-4ffb-9669-66233613856f","http://resolver.tudelft.nl/uuid:b6eda6ca-cab6-4ffb-9669-66233613856f","Coastal Engineering","Van der Velden, E.T.J.M.","","1989","Introduction, waves, sediment transport, littoral transport, lonshore sediment transport, onshore-offshore sediment transport, coastal changes, dune erosion and storm surges, sedimentation in channels and trenches, coastal engineering in practice.","coastal engineering; coastal morphology; sediment transport","en","lecture notes","TU Delft, Department Hydraulic Engineering","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:ae972b2c-176a-4833-b5a6-6f58a938d4c9","http://resolver.tudelft.nl/uuid:ae972b2c-176a-4833-b5a6-6f58a938d4c9","Laboratory observations and calculations of the depth averaged flow patterns in a square harbor on a tidal river","Langendoen, E.J.","","1989","Many harbors in the world suffer from siltation in their basins and in many cases removal of the deposited sediment leads to high costs. This siltation results from a net transport of sediment into the harbor caused by the water motion in the harbor entrance. The water motion is very complex and of a three-dimensional nature. Three main mechanisms can be distinguished: (1) exchange in consequence of water flowing along the mouth of the harbor and the resulting eddies in the harbor entrance, (2) exchange in consequence of variations in water level of the adjacent waterbody (e.g. sea, estuary or river) , and (3) exchange in consequence of a density difference between harbor and adjacent waterbody. For a more extensive discussion of the problem see Langendoen (1988). The first two mechanisms are being examined in a physical model in the Laboratory of Fluid Mechanics of the Delft University. Measurements were made to generate a dataset by which numerical models of the flow in harbor entrances can be tested. A more distant goal of this project is to obtain insight in the influence of the geometry of the entrance on siltation of the harbor. The first part of the research is discussed in this report. It concerns the water motion in a square harbor due to an oscillatory flow in the adjacent waterbody (here a tidal river). The time-varying depth averaged flow patterns in the harbor have been measured. These flow patterns are then compared to the results of preliminary calculations with a numerical model that solves the shallow water equations. In this report a simple geometry of the tidal river and the harbor was considered as a first step. Depth averaged flow patterns were measured and calculated. The phenomena which occurred in the harbor entrance around and after slack water may be important for the exchange of matter between harbor and river. Large parcels of water from the river are exchanged with water from the harbor. This convective exchange is much larger than the exchange around maximum current in the river, when there is only a turbulent transport through the shear layer at the transition between harbor and river. The mathematical model ESTRA, which has been used to study the exchange of a well-mixed solute, also predicted this behavior.","flow pattern; harbor; tidal river; siltation; sediment transport; laboratory observations","en","report","TU Delft, Department of Hydraulic Engineering","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:f92bed59-83dd-43ba-aaa2-0f1d50f0c425","http://resolver.tudelft.nl/uuid:f92bed59-83dd-43ba-aaa2-0f1d50f0c425","Morphological computations","De Vries, M.","","1987","Lecture notes on morphological computations","sediment transport; morhpodynamics","en","book","TU Delft","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:2cf67a5b-d2c4-4287-8ed2-16f1b27bdbcc","http://resolver.tudelft.nl/uuid:2cf67a5b-d2c4-4287-8ed2-16f1b27bdbcc","A depth integrated model for suspended transport","Galappatti, R.","","1983","A new depth averaged model for suspended sediment transport in open channels has been developed based on an asymptotic solution to the two dimensional convection-diffusion equation in the vertical plane. The solution for the depth averaged concentration is derived from the bed boundary condition and the computation of transport rate and entrainment rate are performed therefore. Expressions are derived for adaptation length and time. The model is economical and easy to apply even in unsteady flow situations and compares favourably with the full two dimensional solution for steady flow. The stability of bed level change calculations including numerical effects can be analysed prior to application of the model. The extension to three-dimensions is outlined.","sediment transport; suspended transport","en","report","Delft University of Technology","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:a80c8586-9b32-4b9f-8b93-e71094637ac4","http://resolver.tudelft.nl/uuid:a80c8586-9b32-4b9f-8b93-e71094637ac4","Experiments with non-uniform sediment in case of bed-load transport","Ribberink, J.S.","","1983","An experimental study was carried out in the framework of a research project concerning the development of a mathematical model for morphological computations in rivers in case of non-uniform sediment. The study consists of a series of laboratory experiments in a straight flume under steady, uniform (equilibrium) conditions with a restriction to bed-load transport and dune regime. The flume was fed upstream by different mixtures of two very narrow sieved size fractions. During one experiment the total amount and composition of the input mixture, the water discharge and the downstream water level were kept constant. When equilibrium was reached besides regular registrations of water and bed level the dunes were extensively sampled. The latter occurred in such a way that vertical probability distributions of the size fractions could be determined. The main results of the experiments are: (i) Vertical sorting of the size fractions occurred in all experiments: at the steep lee side of the dunes the coarse size fraction is generally deposited at a lower level than the fine size fraction. Differences in volume concentration per size fraction until 30% occur between upper and lower layers. (ii) A transition layer was found which is generally below the propagating dunes; it has a relatively coarse composition (vertical sorting:) and has a thickness of 0.1 - 0.5 H (H = average dune height). Exchange of size fractions between this layer and the upper bed layer occurs at a time scale much larger than the dune period. (iii) Because of the phenomena described above several assumptions in a mathematical model for non-uniform sediment (Ribberink, 1980) concerning the transport layer and the deposition/erosion of size fractions to/from non-moving bed are generally not fulfilled. (iv) Data are obtained for the verification and development of semi empirical components in the mathematical model (i.e. transportformula per size fraction, predictors for dune height and bed roughness).The theory of Egiazaroff (1965) concerning the critical bed shear stress per size fraction seems to be useful in a bed-load formula per size fraction of the type of Meyer-Peter & Mueller (1948). (v) A bed sampling technique was developed and suggestions are made concerning the conditions of a non -equilibrium experiment which has the aim to verify the above-mentioned mathematical model for non-uniform sediment.","sediment transport; bed load transport; sediment transport measurement","en","report","Delft University of Technology","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:42dc0cb5-c452-4c0c-a1bb-d8e47b9ce011","http://resolver.tudelft.nl/uuid:42dc0cb5-c452-4c0c-a1bb-d8e47b9ce011","Probabilistic approach on course material transport under waves: Vol. 1 Theory and experiment.","Katsui, H.","","1982","The probabilistic design method of a cover layer of pipe line under the horizontal bottom is described. By assuming that the water velocity at the bottom is Rayleigh distributed, probability of bottom shear stress was derived. With a combination of the probability function of bottom shear and a simple sediment transport formula given by Madsen and Grant (1976), the expected transport rate was calculated. The results gave a warning that conventional design methods have a risk to underestimate the amount of loss.of covering material. To confirm the established formulas about inception of motion of particles and sediment transport under waves, some experiments were carried out. As for inception of particle motion, comparison between steady flow condition and wave condition was, done. It turned out that the one gives lower value than the other, and that Shields' curve gives the lower limit of the total experimental data. The data of critical velocity under waves agreed to Komar-Miller's formula which involves the factor of wave period. The critical velocity in the direction of wave propagation was found considerably higher than that against it. Sediment transport rate was measured together with velocity. As had been already presented by van de Graaff and Tilmans (1980), the transport-rate could be related to the Fourier components of the velocity. It could also be related to the maximum and minimum velocity. The influence of a phase lag between the first and second terms of the Fourier components, which is closely related to the acceleration and the deceleration of the total velocity, was not clear yet in that specific condition. Critical velocity obtained by the visual observation generally agreed to the limit line of transport-rate (zero line) on both u1 - u2 plane and u(max) - u(min) plane.","sediment transport; course material; probabilistic approach; waves; shear stress","en","report","","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:7e4a0980-f766-470f-8126-542d03abe9d2","http://resolver.tudelft.nl/uuid:7e4a0980-f766-470f-8126-542d03abe9d2","Information on the Arnhem Sampler (BTMA)","De Vries, M.","","1979","The Subcommittee 6 of the Technical Committee 113 of the International Standardization Organization (ISO) is dealing with measurements of sediment transport in open channels. As a back-ground paper for TC113 this report is written on the BTMA, internationally named the Arnhem Sampler. The BTMA has been developped jointly by Rijkswaterstaat, Directorate Upper Rivers in Arnhem and the Delft Hydraulics Laboratory. The BTMA (Bedload Transport Meter Arnhem) has a relatively long history; the prototype was constructed in the thirties of this century. The BTMA is still in use although insight in the mechanism of bedload transport has been increased. Hence also the insight in the measuring problem and in the use of the BTMA has undergone changes.","BTMA; Arnhem Sampler; sediment transport; measurement; measurement device; bedload transport","en","report","TU Delft, Department of Hydraulic Engineering","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:08388ab0-24aa-48d2-b4ce-c42f71374fcc","http://resolver.tudelft.nl/uuid:08388ab0-24aa-48d2-b4ce-c42f71374fcc","Zandtransporten evenwijdig aan de kust, vergelijking zandtransportformules","Van de Graaff, J.; Van Overeem, J.","","1977","Als T.O.W. onderzoek is door het Waterloopkundig Laboratorium een onderzoek uitgevoerd waarbij enkele moderne zandtransportformules zodanig zijn aangepast dat de gecombineerde werking van golven en stroom in rekening kan worden gebracht. Uit dat onderzoek bleek dat de aangepaste White-Ackers formule het beste aansloot bij een serie modelproeven die als vergelijkingsbasis werd gebruikt. De vakgroep Kustwaterbouwkunde van de Technische Hogeschool Delft heeft een vergelijking tussen de uitkomsten van transportberekeningen met verschillende formules en die met de CERC-formule gemaakt. Om transporten te kunnen berekenen zijn daartoe eerst snelheidsverdelingen evenwijdig aan de kust berekend. Hoewel de CERC-formule geenszins als ideale toetsingsgrond kan worden aangemerkt, is de conclusie gerechtvaardigd dat de aangepaste White-Ackers formule in geen enkel opzicht als een verbetering voor berekeningen van prototypegevallen kan worden beschouwd. De inmiddels wel enigszins geëvolueerde, oorspronkelijke Bijker-forrnule verdient verreweg de voorkeur. Omdat een zinvolle beoordeling van alle aspecten van de kwaliteit van een zandtransportforrnule pas kan geschieden aan de hand van prototype situaties , verdient het aanbeveling een deel van de onderzoekinspanningen, te richten op het verkrijgen van dergelijke situaties.","sediment transport; longshore transport; Bijker formula","nl","report","TU Delft, sectie waterbouw","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:2b62ccd2-cf9b-471e-bd0f-0d888d53822b","http://resolver.tudelft.nl/uuid:2b62ccd2-cf9b-471e-bd0f-0d888d53822b","Modelling of sediment transport: Link in a chain","De Vries, M.","","1977","Rather than reporting on a specific topic of current research in the broad field of sediment transport and river morphology, the writer will give a general contemplation on the state of the art. This will not be a review in the usual sense. The alloted space would then be filled easily with references. References will only be made here if it cannot be avoided. Moreover only sediment transport due to currents will be treated. To avoid confusion it is necessary to indicate that modelling of sediment transport is used at present (1977) in at least three meanings: (i) A theoretical framework for sediment transport proper. This mainly implies a relation between hydraulic parameters and the amount of sediment transport. This framework will have to be supplemented with experimental data before a useful transport predictor is attained. (ii) A mathematical framework for morphological processes in rivers, used to forecast morphological changes in rivers e.g. due to human interference (morphological computations). (iii) A scale model with mobile bed of a river in order to carry out similar predictions as under (ii) (mobile-bed scale models). In which follows the vague term ""modelling of sediment transport"" will be avoided if confusion may be introduced.","sediment transport; river morphology","en","report","TU Delft","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:ed331010-c8e8-4f42-9396-9ade25ce17ae","http://resolver.tudelft.nl/uuid:ed331010-c8e8-4f42-9396-9ade25ce17ae","Morphological computations","De Vries, M.","","1976","Lecture notes sediment transport in rivers, formulas and numerical models.","sediment transport; river morphology; bedload transport; river dunes; lecture note f10a","en","lecture notes","TU Delft, Section Hydraulic Engineering","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:2627433e-275e-4327-8841-ae998a6c525c","http://resolver.tudelft.nl/uuid:2627433e-275e-4327-8841-ae998a6c525c","Erosion and transport of bed-load sediment","Fernandez Luque, R.","Hinze, J.O. (promotor)","1974","In this thesis first a general derivation is given of the 'macro'-equations of mass- and linear-momentum balance that govern the mo'mentum transfer from a Newtonian fluid to rigid particles in a fluid-solid mixture. In particular, attention is paid to a) the attenuation of viscous-momentum transfer from the boundary to the interior of a granular bed subject to a surface flow, b) the drag and lift forces exerted by a turbulent shear flow on particles of the bed surface, and, c) the balance of forces acting on a bed load under uniform-flow conditions. It is shown that filter flow driven by shearing along the boundary of a granular sediment bed exerts a drag force on a layer of only two or three particle diameters within the bed. A drag force on the bulk mass of sediment is only exerted by a pore-pressure gradient. Stability conditions are formulated for a loose granular bed subject to erosive flow, at SHIELDS' grain-movement condition and dUring bed-load transport. 'Macro'-stresses acting along 'wavy' surfaces parallel to the bed are defined for that purpose, and an attenuation factor is introduced for the transmission of turbulent fluid shear from the surface towards the interior of the bed. It is shown that SHIELDS' dimensionless expression for the critical bed shear stress at the threshold of continuous sediment motion, 1/Phi , must reach a constant value for low-shear Reynolds' numbers (Re* < O. 5), as long as there is no cohesion between the particles. It is concluded that the bed load, consisting of particles rolling and saltating over the bed, must reduce the maximum turbulent fluid shear at the bed surface, at sufficiently high bed shear stress, to the critical threshold drag that would lead to the initiation of non-ceasing scour.","sediment transport; Shields; bed-load transport; erosion","en","doctoral thesis","Krips Repro, Meppel","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:02dd87f6-a156-4f63-8a97-0dc6b0f6bac2","http://resolver.tudelft.nl/uuid:02dd87f6-a156-4f63-8a97-0dc6b0f6bac2","Sedimenttransport","De Vries, M.","","1974","Collegedictaat f10. In deze handleiding kan slechts een eerste kennismaking met de problemen worden gegeven, die samenhangen met het transport van sedimenten als gevolg van de waterbeweging. Door de interactie van waterbeweging en sedimentbeweging is er sprake van gecompliceerde processen, die zich slecht ten dele theoretisch laten benaderen. Er is derhalve een sterk experimentele benadering nodig. Het sterk empirische karakter van de beschikbare oplossingen voor deelproblemen maakt dat de toepassing bijzonder kritisch moet gebeuren. Steeds moet de vraag worden gesteld of een bepaalde theorie voor het beschouwde geval weI mag worden toegepast.","sediment transport; bodemtransport; spoeltransport; zwevend transport","nl","lecture notes","TU Delft, Section Hydraulic Engineering","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:3979e4b4-83d9-44ae-aa0f-8106e749a9e3","http://resolver.tudelft.nl/uuid:3979e4b4-83d9-44ae-aa0f-8106e749a9e3","Aspecten van zandtransport in open waterlopen","De Vries, M.","","1971","College ""Materiaaltransport B.O."", sedimenttransport in rivieren.","sediment transport; rivieren; collegedictaat f10a","nl","lecture notes","TU Delft, Section Hydraulic Engineering","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:e24ebff9-024b-4fa7-b2e4-9a8c5af1ca30","http://resolver.tudelft.nl/uuid:e24ebff9-024b-4fa7-b2e4-9a8c5af1ca30","Application of luminophores in sandtransport-studies","De Vries, M.","Hinze, J.O. (promotor); Van Spiegel, E. (promotor)","1966","The quantitative determination of bed-material-transport by means of tracers has been considered. For a stationary-stochastical transport-condition the dispersion of tracers has been described by a diffusion-equation of the gradienttype. The parameters of the dispersion-model are derived from the measured concentrations by a least-squares procedure. The measuring-technique has been based on the application of fluorescent tracers (luminophores). Some flume-tests show that the method proposed yields fair quantitative answers.","sediment transport; tracers; bed load transport","en","doctoral thesis","Meinema, Delft","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","","" "uuid:66b299fb-d0f5-438b-bd02-0dd7b4d06c61","http://resolver.tudelft.nl/uuid:66b299fb-d0f5-438b-bd02-0dd7b4d06c61","Analytical and experimental study of bed load distribution at alluvial diversions","Riad, K.","Thijsse, J.T. (promotor)","1961","It has long been observed that at most canal bifurcations the water diverted to the branch does not carry sediment in direct proportion to the rate of flow. Usually, the major part of sediment reaching a bifurcation is diverted into the small branches. This phenomenon has always bothered engineers responsible for the maintenance of irrigation and navigation canals which branch off relatively large alluvial streams. Experimental studies of this problem have usually been limited to the use of fixed bed flumes in which the velocity of flow was measured at different sections in the vicinity of the bifurcation. The distribution of the velocity both vertically and horizontally were then determined and considered as the basis of comparison between different cases. Some investigators studied the pattern of flow near the bed either by the introduction of sediment particles or pottasium permanganate crystals. In the present experimental study, sand was used as bed material and measurements in any run were only taken after the sand movement had reached equilibrium, when the rate of sediment feeding was equal to the sum of the rates of sediment being trapped at the end of main and branch channels. The experimental set-up consisted of a straight flume 20 m long and 0.80 m wide which represented the main canal and a lO m. X 0.50 m flume which branched off the main flume at 45 degrees, 8.20 m. from the upstream end and which represented the branch canal. At first a series of tests was carried out without a sand bed in order to study the wall roughness. Then the sand bed was introduced and a series of tests was carried out to determine the effect of the ratio between branch and main canal discharges upon the sediment behaviour at the bifurcation. In order to control the rate of sediment diversion into a branch, some artificial means have to be applied. In this respect the writer has experimented with the application of dividing walls which direct the bottom flow and guide vanes which direct the surface flow. In general and within the scope of the experiments, the guide vanes gave the better results. Hence, tests were concentrated on the determination of the best location and direction for such vanes, and the results of these experiments led to the recommendations described on fig. 50.","sediment transport; bed load; river diversion; river morphology","en","doctoral thesis","Waltman Delft","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""