78 results on '"de Swart, Huib E."'
Search Results
52. Nonlinear modelling of shoreface-connected ridges
- Author
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de Swart, Huib E., Walgreen, M, Calvete Manrique, Daniel|||0000-0002-5402-5137, and Vis-Star, N C
- Subjects
Dunes ,Física [Àrees temàtiques de la UPC] ,Sediments marins ,Sand waves ,Sediment transport - Abstract
The evolution of shoreface-connected sand ridges on micro-tidal inner shelves and the variations in the mean grain size over these ridges are investigated with process-based models. A review of previous studies is presented, as well as new results that concern the influence of grain sorting on the finite-amplitude behaviour of the ridges, the application of the model to La Barrosa beach and the role of wave-topography feedbacks. The ridges initially form due to morphodynamic self-organisation, in which the presence of waves and a storm-driven current are crucial. Predicted growth time scales, migration speeds, topography and spatial pattern of the mean grain size agree with field data collected on micro-tidal shelves in the case that both bedload and suspended load sediment transport are accounted for, together with spatially non-uniform wave orbital motion. The model can not successfully explain the presence of large-scale ridges observed on La Barrosa inner shelf, because strong and complex behaving tidal currents occur in that area. Nonlinear model simulations show that on the long term the height of the ridges evolves towards a finite, constant value, whilst their migration speed hardly changes during the evolution. In the saturated stage the ridges have asymmetrical profiles, with steep slopes on the downstream sides. The maximum variation in mean grain size also tends to a constant value and during the evolution the spatial lag between the patterns in the mean grain size and topography decreases. The processes that cause these changes are identified and explained. Model results can be obtained for transverse bottom slopes up to 50% of their observed values on micro-tidal shelves. Extrapolation of results to realistic values of the inner shelf slope yields, in case of Long Island shelf, a final height that agrees with observed ridge heights, but the modelled variation in mean grain size is small compared to field data. Finally, the response of ridges to large-scale interventions is considered. Experiments reveal that extraction of sand on the inner shelf causes a decrease of the sand volume stored in the surf zone.
- Published
- 2008
- Full Text
- View/download PDF
53. Non-linear response of shoreface-connected sand ridges
- Author
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de Swart, Huib E., Calvete Manrique, Daniel, Universitat Politècnica de Catalunya. Departament de Física Aplicada, and Universitat Politècnica de Catalunya. DF - Dinàmica No Lineal de Fluids
- Subjects
Dunes ,Física [Àrees temàtiques de la UPC] ,Sand waves - Abstract
A non-linear morphodynamic model of a microtidal coastal shelf is used to study the response of shoreface-connected sand ridges and the net sand balance of the shelf to large-scale interventions. The model describes the interaction between storm-driven currents and the erodible bottom. The transport of sediment comprises both bedload and suspended load contributions and is due to the joint action of waves (stirring of sediment from the bed) and net currents (causing transport). Three basic types of interventions are studied: extracting sand from ridges, nourishing sand at the shelf and constructing navigation channels. The model results indicate that for all interventions studied a relatively fast local recovery (time scale of decades to centuries) of the disturbed bathymetry to its original pattern takes place. Readjustment of the global system to its original equilibrium state (the saturation process) occurs on a longer time scale (several centuries). During the adjustment stage, significant net sand exchanges between inner shelf and adjacent outer shelf and near-shore zone occur. The results further suggest that extraction of sand from the shelf and dredging of navigation channels have negative implications for the stability of the beach (its sand volume decreases).
- Published
- 2003
54. Role of asymmetric tidal mixing in the subtidal dynamics of narrow estuaries
- Author
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Cheng, Peng, primary, de Swart, Huib E., additional, and Valle‐Levinson, Arnoldo, additional
- Published
- 2013
- Full Text
- View/download PDF
55. Linear stability analysis - tidal sandbanks
- Author
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Hulscher, Suzanne J.M.H., de Swart, Huib E., O'Connor, B.A., and Faculty of Engineering Technology
- Published
- 1997
56. EFFECT OF SURFACE ROLLERS ON THE FORMATION OF CRESCENTIC BARS
- Author
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Calvete, Daniel, primary, Ribas, Francesca, additional, De Swart, Huib E., additional, and Falques, Albert, additional
- Published
- 2012
- Full Text
- View/download PDF
57. Effects of navigational works on morphological changes in the bar area of the Yangtze Estuary
- Author
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Jiang, Chenjuan, primary, Li, Jiufa, additional, and de Swart, Huib E., additional
- Published
- 2012
- Full Text
- View/download PDF
58. A numerical study of residual circulation induced by asymmetric tidal mixing in tidally dominated estuaries
- Author
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Cheng, Peng, primary, Valle-Levinson, Arnoldo, additional, and de Swart, Huib E., additional
- Published
- 2011
- Full Text
- View/download PDF
59. Residual Currents Induced by Asymmetric Tidal Mixing in Weakly Stratified Narrow Estuaries
- Author
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Cheng, Peng, primary, Valle-Levinson, Arnoldo, primary, and de Swart, Huib E., additional
- Published
- 2010
- Full Text
- View/download PDF
60. The generation of offshore tidal sand banks and sand waves
- Author
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Hulscher, Suzanne J.M.H., de Swart, Huib E., de Vriend, Huib J., Sub Physical Oceanography, Marine and Atmospheric Research, Sub Physical Oceanography, Marine and Atmospheric Research, and Faculty of Engineering Technology
- Subjects
Scale (ratio) ,Flow (psychology) ,Mode (statistics) ,Geology ,Mechanics ,Aquatic Science ,Ellipse ,Oceanography ,Physics::Geophysics ,IR-20593 ,Amplitude ,METIS-124196 ,Submarine pipeline ,Geotechnical engineering ,Astrophysics::Earth and Planetary Astrophysics ,Sediment transport ,Linear stability - Abstract
A simple morphological model is considered which describes the interaction between a tidal flow and an erodible bed in a shallow sea. The basic state of this model describes a spatially uniform tide over a flat bottom where the flow vector is represented as a tidal ellipse. The linear stability of this solution is analysed with respect to bed form perturbations. Results are presented for both a uni-directional and circular tide. In the former case the wave-length and the orientation of the fastest growing bed mode agree well with those of tidal sand banks. However, this model only predicts the growth of large-scale sand ridges. With a simplified numerical model we tentatively show that the effects of secondary currents on the sediment transport trigger the formation of instabilities at an essentially smaller scale, viz, sand waves. Another limitation of a model with uni-directional tides is that no selective modes found are the first to become unstable if the model parameters are varied. In the case of a circular tide, critical model parameters are found below which the basic state is stable. We conclude that this provides a starting point for the development of a weakly non-linear analysis, which will yield information on the amplitude behaviour of marginally growing bed forms.
- Published
- 1993
61. Effect of bottom stress formulation on modelled flow and turbidity maxima in cross-sections of tide-dominated estuaries
- Author
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Schramkowski, George P., primary, de Swart, Huib E., additional, and Schuttelaars, Henk M., additional
- Published
- 2009
- Full Text
- View/download PDF
62. Long bed waves in tidal seas: an idealized model
- Author
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BLONDEAUX, PAOLO, primary, DE SWART, HUIB E., additional, and VITTORI, GIOVANNA, additional
- Published
- 2009
- Full Text
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63. 91. THE ROLE OF THE DEPTH-AVERAGED CONCENTRATION IN COASTAL MORPHODYNAMICS
- Author
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Calvete, Daniel, primary, Falqués, Albert, additional, de Swart, Huib E., additional, Dodd, Nicholas, additional, Ribas, Francesca, additional, and Garnier, Roland, additional
- Published
- 2009
- Full Text
- View/download PDF
64. Modelling lateral entrapment of suspended sediment in estuaries: The role of spatial lags in settling and M4 tidal flow.
- Author
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Zhongyong Yang, de Swart, Huib E., Heqin Cheng, Chenjuan Jiang, and Valle-Levinson, Arnoldo
- Subjects
- *
SUSPENDED sediments , *TIDES , *SETTLING basins , *ESTUARIES , *HYDRODYNAMICS - Abstract
The effect of the joint action ofM2andM4tidal flow, residual flow and spatial settling lag on the lateral entrapment of sediment is examined in tidally dominated estuaries with an idealized model that assumes along-estuary uniform conditions. Approximate solutions are obtained for arbitrary cross-channel bed profiles by scaling and perturbation analysis. The hydrodynamics include externally drivenM2tidal flow, externally and internally drivenM4tidal flow and residual flow driven by horizontal density gradient, river discharge and nonlinear advection. The sediment concentration includes a mean component, anM2component driven by bed erosion and anM2component driven by both bed erosion and inertial terms. Sediment availability is calculated by imposing a morphodynamic equilibrium condition. The model is applied to a transect in the James River estuary where data of flow and suspended sediment concentration are available. Two types of sediment are separately considered, viz., fine silt and coarse silt. Residual advective transport of sediment by the lateral flow induces trapping of sediment over the left shoal (looking landward). Model results also show that the incorporation ofM4tidal flow and spatial settling lag leads to a second sediment trapping region over the right shoal. Model results are qualitatively in good agreement with the observations. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
65. Residual Currents Induced by Asymmetric Tidal Mixing in Weakly Stratified Narrow Estuaries.
- Author
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Peng Cheng, Valle-Levinson, Arnoldo, and de Swart, Huib E.
- Subjects
OCEAN currents ,TIDAL currents ,WATER currents ,GULF Stream ,OCEANOGRAPHY - Abstract
Residual currents induced by asymmetric tidal mixing were examined for weakly stratified, narrow estuaries using analytical and numerical models. The analytical model is an extension of the work of R. K. McCarthy, with the addition of tidal variations of the vertical eddy viscosity in the longitudinal momentum equation. The longitudinal distribution of residual flows driven by asymmetric tidal mixing is determined by the tidal current amplitude and by asymmetries in tidal mixing between flood and ebb. In a long channel, the magnitude of the residual flow induced by asymmetric tidal mixing is maximum at the estuary mouth and decreases upstream following the longitudinal distribution of tidal current amplitude. Larger asymmetry in tidal mixing between flood and ebb produces stronger residual currents. For typical tidal asymmetry, mixing is stronger during flood than during ebb and results in two-layer residual currents with seaward flow near the surface and landward flow near the bottom. For reverse tidal asymmetry, mixing is weaker during flood than during ebb and the resulting residual flow is landward near the surface and seaward near the bottom. Also, the residual flow induced by tidal asymmetry has the same order of magnitude as the density-driven flow and therefore is important to estuarine dynamics. Numerical experiments with a primitive-equation numerical model [the Regional Ocean Modeling System (ROMS)] generally support the pattern of residual currents driven by tidal asymmetry suggested by the analytical model. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
66. Effect of advective and diffusive sediment transport on the formation of local and global bottom patterns in tidal embayments.
- Author
-
Van Leeuwen, Sonja M. and De Swart, Huib E.
- Subjects
- *
TIDAL basins , *SEDIMENTATION & deposition , *SAND bars , *INLETS , *HYDRODYNAMICS - Abstract
Bathymetric field data of tidal basins reveal two main classes of bottom patterns: (1) tidal bars, located near the entrance of the basin (length scale determined by the embayment width) and (2) global channel-shoal patterns which scale with the basin length. Previous models were able to describe only either one of these patterns. In this paper it is shown that both of them can be investigated within the framework of an idealised model of a rectangular tidal embayment, with fixed side walls and an erodible bed. The water motion is described by the depth-averaged shallow-water equations and is forced by a prescribed vertical tide at the seaward entrance. Sediment is transported as suspended load and only realistic values of the bottom friction parameter are considered. By assuming the ratio of embayment length over tidal wave length to be small, the model allows for a morphodynamic equilibrium, characterised by a spatially uniform tide moving over a bottom which slopes upwards toward the landward boundary. This equilibrium is unstable for a range of values of the model parameters, such that growth of bedforms occurs. Both global and local bottom patterns are found. In this study particular emphasis is laid on the mechanism governing the growth of a new type of localised bottom pattern. These patterns consist of small bars located near the entrance of the basin, resembling multiple row bars, and are found when advective sediment fluxes prevail over diffusive sediment fluxes. The formation process of these new bedforms is discussed in detail. The results agree well with field data. Comparison of the results with those obtained with a process-based, numerical model shows that, although the idealised model is strongly simplified, it is capable of producing the essential morphodynamics. Therefore, the idealised model is a useful tool to investigate mechanisms of bottom pattern growth. [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
67. A model for grain-size sorting over tidal sand ridges.
- Author
-
Walgreen, M., De Swart, Huib E., and Calvete, D.
- Subjects
- *
SAND waves , *SEDIMENTARY structures , *TIDES , *OCEAN circulation , *OCEANOGRAPHY - Abstract
A model was developed and analyzed to quantify the effect of graded sediment on the formation of tidal sand ridges. Field data reveal coarse (fine) sediment at the crests (in the troughs), but often phase shifts between the mean grain-size distribution and the bottom topography occur. Following earlier work, this study is based on a linear stability analysis of a basic state with respect to small bottom perturbations. The basic state describes an alongshore tidal current on a coastal shelf. Sediment is transported as bed load and dynamic hiding effects are accounted for. A one-layer model for the bed evolution is used and two grain size classes (fine and coarse sand) are considered. Results indicate an increase in growth and migration rates of tidal sand ridges for a bimodal mixture, whilst the wavelength of the ridges remains unchanged. A symmetrical externally forced tidal current results in a grain-size distribution which is in phase with the ridges. Incorporation of an additional external M4 tidal constituent or a steady current results in a phase shift between the grain-size distribution and ridge topography. These results show a general agreement with observations. The physical mechanism responsible for the observed grain-size distribution over the ridges is also discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
68. Non-linear channel--shoal dynamics in long tidal embayments.
- Author
-
Schramkowski, George P., Schuttelaars, H. M., and De Swart, Huib E.
- Subjects
TIDES ,OCEAN circulation ,EQUILIBRIUM ,HYDRODYNAMICS ,ESTUARIES - Abstract
The dynamics of finite-amplitude bed forms in a tidal channel is studied with the use of an idealized morphodynamic model. The latter is based on depth-averaged equations for the tidal flow over a sandy bottom. The model considers phenomena on spatial scales of the order of the tidal excursion length. Transport of sediment mainly takes place as suspended load. The reference state of this model is characterized by a spatially uniform M
2 tidal current over a fixed horizontal bed. The temporal evolution of deviations from this reference state is governed by amplitude equations: these are a set of non-linear equations that describe the temporal evolution of bed forms. These equations are used to obtain new morphodynamic equilibria which may be either static or time-periodic. Several of these bottom profiles show strong similarity with the tidal bars that are observed in natural estuaries. The dependence of the equilibrium solutions on the value of bottom friction and channel width is investigated systematically. For narrow channels (width small compared to the tidal excursion length) stable static equilibria exist if bottom friction is slightly larger than rcr . For channel widths more comparable to the tidal excursion length, multiple stable steady states may exist for bottom friction parameter values below rcr . Regardless of channel width, stable time-periodic equilibria seem to emerge as the bottom friction is increased. [ABSTRACT FROM AUTHOR]- Published
- 2004
- Full Text
- View/download PDF
69. The effect of velocity veering on sand transport in a shallow sea.
- Author
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Shapiro, Georgy I., Van der Molen, Johan, and De Swart, Huib E.
- Subjects
SPEED ,SEDIMENTATION & deposition ,EROSION ,OCEAN waves ,HYDRODYNAMICS - Abstract
This study aims at comparing and contrasting two different models for sand transport by currents in a shallow sea to illustrate the effect of velocity veering. The first model uses the Bailard-type formulation, which allows calculation of erosion/deposition rates at a fixed location on the sea floor via the divergence of horizontal sediment fluxes. The second model is a semi-analytical 2.5-dimensional model, which takes into account the time lag between erosion and deposition events and the velocity veering within the sediment-laden (nepheloid) layer caused by the Coriolis force. The velocity veering implies that the direction of the sediment flux is generally different from the direction of the surface flow. The latter model was designed for rapid, semi-analytical computations of sediment transport, using flow fields from 2-DH numerical models. The two models use a matching set of parameters to provide identical values for the bottom stress and suspended sediment load for a uniform steady current at any given surface velocity. The two models were compared in a range of sand grain sizes 50--500 µm and current speeds up to 1 m s
-1 for an idealised square region (100 100 km) of a shelf sea of constant depth. The erosion/deposition patterns and suspension load were examined in three settings: (1) uniform steady flow, (2) straight jet, (3) meandering jet. It was found that both the rates and, in particular,the spatial distribution of the areas of erosion/deposition differ significantly between the models in cases (2) and (3). This difference can be attributed to additional flux divergence due to velocity veering. A comparison of model results with field data, collected at Long Island Shelf, supports the relevance of Coriolis-induced veering of currents on the direction of the sediment flux. [ABSTRACT FROM AUTHOR]- Published
- 2004
- Full Text
- View/download PDF
70. Understanding Coastal Morphodynamics Using Stability Methods.
- Author
-
Dodd, Nick, Blondeaux, Paolo, Calvete, Daniel, De Swart, Huib E., Falqués, Albert, Hulscher, Suzanne J.M.H., Rózyński, Greg, and Vittori, Giovanna
- Subjects
COASTS ,EVOLUTIONARY theories ,SEASHORE - Abstract
Stability methods, as they are applied in describing the initiation, growth and long term evolution of morphological features, are discussed. In particular, their use in describing large-scale, long-term rhythmic morphological features is highlighted. The analysis of such models indicates that many rhythmic bottom features arise from an inherent instability of a morphodynamical system, rather than being forced by external conditions. A synopsis of their theoretical basis is given, and the assumptions commonly pertaining to their use are described. These models, which can be applied more efficiently than many other process-oriented models, are categorized, and the kind of information that they can provide is also described. Finally, their relation to other areas and techniques of long-term, aggregated scale morphodynamics is discussed, and their usefulness to and applicability by the practitioner is summarized. [ABSTRACT FROM AUTHOR]
- Published
- 2003
71. Non-linear response of shoreface-connected sand ridges to interventions.
- Author
-
De Swart, Huib E. and Calvete, Daniel
- Subjects
- *
SAND waves , *SEDIMENTARY structures , *STABILITY (Mechanics) , *COASTS , *SEASHORE - Abstract
A non-linear morphodynamic model of a microtidal coastal shelf is used to study the response of shoreface-connected sand ridges and the net sand balance of the shelf to large-scale interventions. The model describes the interaction between storm-driven currents and the erodible bottom. The transport of sediment comprises both bedload and suspended load contributions and is due to the joint action of waves (stirring of sediment from the bed) and net currents (causing transport). Three basic types of interventions are studied: extracting sand from ridges, nourishing sand at the shelf and constructing navigation channels. The model results indicate that for all interventions studied a relatively fast local recovery (time scale of decades to centuries) of the disturbed bathymetry to its original pattern takes place. Readjustment of the global system to its original equilibrium state (the saturation process) occurs on a longer time scale (several centuries). During the adjustment stage, significant net sand exchanges between inner shelf and adjacent outer shelf and near-shore zone occur. The results further suggest that extraction of sand from the shelf and dredging of navigation channels have negative implications for the stability of the beach (its sand volume decreases). [ABSTRACT FROM AUTHOR]
- Published
- 2003
- Full Text
- View/download PDF
72. Sensitivity of tidal motion in well-mixed estuaries to cross-sectional shape, deepening, and sea level rise
- Author
-
Ensing, Erik, de Swart, Huib E., Schuttelaars, Henk M., Sub Physical Oceanography, and Marine and Atmospheric Research
- Subjects
CURRENTS ,TIDES ,CIRCULATION ,YANGTZE ESTUARY ,Tidal flow ,Oceanography ,Idealised model ,Resonance ,MODEL ,Shallow water equations ,NORTH-SEA ,CHANNEL ,Ems estuary ,ASYMMETRY ,HIGHLY TURBID ESTUARIES ,SEDIMENT TRANSPORT - Abstract
For well-mixed estuaries, key physical mechanisms are identified and quantified that cause changes in characteristics of the semi-diurnal sea surface elevation and lateral velocity due to modifications of the lateral bottom profile, channel deepening, and sea level rise. This is done by decomposing solutions of a new analytical model into components relating to different physical processes. The default geometry and parameter values are representative for the Ems estuary, with a converging width and a reflective landward boundary. The default Gaussian lateral bottom profile is modified to obtain profiles with the same cross-sectional area, but with a different skewness or steepness. Results show that a steeper lateral bottom profile leads to amplification of the sea surface elevation. The width convergence is shown to influence the resonance characteristics. Channel deepening and sea level rise result in amplification of the sea surface elevation until a resonance peak is reached. When flooding is incorporated, the amount of sea level rise at which maximum tidal amplification occurs is found to be about two times lower. When using a symmetric Gaussian bottom profile, the lateral tidal flow is determined by Coriolis deflection of longitudinal flow and lateral density gradients caused by differential salt advection. However, an additional lateral tidal flow component incorporating the effect of continuity related to sea level variations and longitudinal gradients in longitudinal flow is shown to become increasingly important for skewed lateral bottom profiles. Furthermore, the lateral flow due to the lateral density gradient is enhanced for bottom profiles with increased steepness.
- Full Text
- View/download PDF
73. Transverse structure of tidal and residual flow and sediment concentration in estuaries
- Author
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Huijts, Karin M. H., de Swart, Huib E., Schramkowski, George P., and Schuttelaars, Henk M.
- Subjects
Oceanography ,Physics::Geophysics - Full Text
- View/download PDF
74. Effect of shelf morphodynamics on coastline change: modelling free behaviour and response to interventions on the shelf.
- Author
-
de Swart, Huib E., Wolf, Thom B.J., and Nnafie, Abdel
- Subjects
- *
OCEAN waves , *ARTIFICIAL islands , *COASTAL changes , *SAND waves - Abstract
The dynamics of the surf zone strongly depend on the characteristics of incoming sea waves,. The latter are determined by the local wind climate, but also by the bathymetry of the inner shelf, e.g. sand ridges cause wave refraction and dissipate part of the wave energy. As the shelf bathymetry evolves on decadal to centennial time scales, due to spatial variations in tide- and wave-induced sand transport, knowledge on how shelf bathymetry affects the large-scale coastal evolution is important. This study investigates the natural hydro- and morphodynamics of a mesotidal coastal system (shelf and surf zone) and their response to interventions on the shelf. For this, the coupled Delft3D-SWAN numerical model is employed to solve for tides, waves, sand transport and bed level update on the inner shelf. A one-line model is used to calculate large-scale evolution of the coastline from gradients in the longshore sand transport in the surf zone. This transport is given by the CERC formula, where its input is derived from the wave output of the shelf model. Results will be shown for a domain that crudely mimics the Belgian continental shelf. The natural behaviour of the inner shelf is studied by conducting spin-up runs for a period of 1000 years, starting from an initially linear bottom profile in the cross-shore direction. Subsequently, several interventions are created (in particular artificial islands) and the response of the system to these perturbations is studied. It will first be shown that a full process-based morphodynamic model is able to simulate the formation of mature tidal sand ridges on a shelf with a sloping bottom. The variable bathymetry of the shelf has a substantial impact on coastal erosion and accretion patterns. Second, the construction of an island strongly affects the dynamics of the sand ridges and also gives rise to substantial accretion of the coast behind the island and erosion further downstream. Third, shelf dynamics and coastal accretion and erosion rates will be presented for different positions and sizes of the island, as well as for multiple islands. [ABSTRACT FROM AUTHOR]
- Published
- 2019
75. Formation of shoreface-connected sand ridges: effects of rigid-lid approach, quasi-steady approach and wave-topography feedbacks
- Author
-
Nnafie, Abdel, de Swart, Huib E., Garnier, Roland, Calvete Manrique, Daniel|||0000-0002-5402-5137, Universitat Politècnica de Catalunya. Departament de Física Aplicada, and Universitat Politècnica de Catalunya. DF - Dinàmica No Lineal de Fluids
- Subjects
Dunes ,Física [Àrees temàtiques de la UPC] ,Sand waves - Abstract
The initial- and long-term evolution of shoreface-connected sand ridges (sfcr) is investigated with a new nonlinear model (MORFO56) that employs finite difference methods, rather than spectral methods. MORFO56 uses depth-averaged shallow water equations, including sediment transport and bed updating. Moreover, it includes full wave-topography feedbacks, wave shoaling and refraction, and wave radiation stresses. First, effects of relaxing the rigid-lid assumption and quasi-steadiness on the initial growth and migration of sfcr are quantified, by conducting a series of short-term runs. It turns out that assuming a free lid and unsteady flow results in larger wavelengths and larger migration speeds of sfcr. Furthermore, the new model is able to simulate the finite amplitude behaviour of sfcr for more realistic bottom slopes than earlier spectral models. Finally, the role of wave-topography feedbacks in the initial formation of sfcr is examined. Model simulations show that sfcr in the presence of these feedbacks are more trapped to the shoreface, with an offshore extent of approximately 1 km. Moreover, growth of sfcr is enhanced considerably by wave-topography feedbacks. The specific inclusion of radiation stresses does not affect this result.
76. On the physics behind coastal morphodynamic patterns
- Author
-
Ribas Prats, Francesca, Falqués Serra, Albert, de Swart, Huib E., Dodd, Nicholas, Garnier, Roland Charles, Calvete Manrique, Daniel, Universitat Politècnica de Catalunya. Departament de Física, and Universitat Politècnica de Catalunya. DF - Dinàmica No Lineal de Fluids
- Subjects
coastal morphodynamic patterns ,sand ridges ,Física [Àrees temàtiques de la UPC] ,beach cusps ,education ,Enginyeria de costes ,Coast changes ,Sedimentació ,Sediment transport ,Coastal engineering ,self-organization ,nearshore sand bars
77. Modelling the formation of transverse sand bars: application to Duck beach, USA
- Author
-
Ribas Prats, Francesca|||0000-0003-4701-5982, de Swart, Huib E., Calvete Manrique, Daniel|||0000-0002-5402-5137, Falqués Serra, Albert|||0000-0002-3945-1509, Universitat Politècnica de Catalunya. Departament de Física Aplicada, and Universitat Politècnica de Catalunya. DF - Dinàmica No Lineal de Fluids
- Subjects
Platges ,Seashore ,Enginyeria civil::Geologia [Àrees temàtiques de la UPC] ,Sand bars - Abstract
A morphodynamic model has been applied to explain the formation of transverse sand bars at Duck beach, USA. The model describes the feedback between waves, rollers, depth-averaged currents and bed evolution, so that self-organized processes can develop. The wave and bathymetric conditions measured at Duck are used to perform the simulations. Subsequently, modelled bar characteristics are compared with those observed there. Realistic positive feedback leading to formation of the observed bars only occurs if the resuspension of sediment due to bore turbulence is included in the model. Also, the offshore root mean square wave height must be larger than 0.5 m and the offshore wave incidence angle larger than 15o (offshore boundary is at 8 m depth), conditions that occur at Duck only 25% of the time. The modelled shape (wavelength, cross-shore extent and crest orientation) and growth rate agree with data, but the model overestimates the migration rates.
78. THE ROLE OF THE DEPTH-AVERAGED CONCENTRATION IN COASTAL MORPHODYNAMICS.
- Author
-
Calvete, Daniel, Falques, Albert, de Swart, Huib E., Dodd, Nicholas, Ribas, Francesca, and Garnier, Roland
- Subjects
COASTAL changes ,TOPOGRAPHY ,HYDRODYNAMICS ,BARS (Geomorphology) ,BEACHES - Published
- 2009
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