19 results on '"de Swart, Huib E."'
Search Results
2. Sensitivity of tidal characteristics in double inlet systems to momentum dissipation on tidal flats: a perturbation analysis
- Author
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Hepkema, Tjebbe M., de Swart, Huib E., Zagaris, Antonios, and Duran–Matute, Matias
- Published
- 2018
- Full Text
- View/download PDF
3. Longitudinal variation in lateral trapping of fine sediment in tidal estuaries: observations and a 3D exploratory model
- Author
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Chen, Wei and de Swart, Huib E.
- Published
- 2018
- Full Text
- View/download PDF
4. Turbidity maxima in estuarine networks: Dependence on fluvial sediment input and local deepening/narrowing with an exploratory model
- Author
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Wang, Jinyang, Dijkstra, Yoeri M., de Swart, Huib E., Sub Physical Oceanography, Marine and Atmospheric Research, Sub Physical Oceanography, and Marine and Atmospheric Research
- Subjects
Global and Planetary Change ,sediment trapping ,turbidity maximum ,sediment overspill ,tidal network ,Ocean Engineering ,Aquatic Science ,Environmental Science (miscellaneous) ,Oceanography ,sediment transport ,Water Science and Technology - Abstract
An estuarine turbidity maximum (ETM) results from various subtidal sediment transport mechanisms related to, e.g., river, tides, and density gradients, which have been extensively analysed in single-channel estuaries. However, ETMs have also been found in estuaries composed of multiple interconnected tidal channels, where the water and suspended fine sediments are exchanged at the junctions with possible occurrence of sediment overspill. The overall aim of this study is to understand the processes that determine the ETM dynamics in such channel networks. Specifically, focusing on the ETMs formation due to sediment transport by river flow and density-driven flow, the dependence of ETM locations in an idealised three-channel network on fluvial sediment input and the local deepening and narrowing of a seaward channel is investigated. It is found that the ETM dynamics in channels of a network is coupled, and hence, changes in one channel affect the ETM pattern in all channels. Sensitivity results show that, keeping river discharge fixed, a larger fluvial sediment input leads to the upstream shift of ETMs and an increase in the overall sediment concentration. Both deepening or narrowing of a seaward channel may influence the ETMs in the entire network. Furthermore, the effect of either deepening or narrowing of a seaward channel on the ETM locations in the network depends on the system geometry and the dominant hydrodynamic conditions. Therefore, the response of the ETM location to local geometric changes is explained by analysing the dominant sediment transport mechanisms. In addition to the convergence of sediment transport mechanisms in single-estuarine channels, ETM dynamics in networks is found to be strongly affected by net exchange of sediment between the branches of a network. We find that considering the sensitivity of net sediment transport to geometric changes is needed to understand the changing ETM dynamics observed in a real estuarine network.
- Published
- 2022
5. Influence of the back-barrier basin length on the geometry of ebb-tidal deltas
- Author
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Ridderinkhof, Wim, de Swart, Huib E., van der Vegt, Maarten, and Hoekstra, Piet
- Published
- 2014
- Full Text
- View/download PDF
6. 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., de Swart, Huib E., and Schuttelaars, Henk M.
- Published
- 2010
- Full Text
- View/download PDF
7. Emerging crescentic patterns in modelled double sandbar systems under normally incident waves
- Author
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Coco, Giovanni, Calvete, Daniel, Ribas, Francesca, De Swart, Huib E., Falqués, Albert, Dep Natuurkunde, Sub Physical Oceanography, Marine and Atmospheric Research, Dep Natuurkunde, Sub Physical Oceanography, Marine and Atmospheric Research, Universitat Politècnica de Catalunya. Departament de Física, and Universitat Politècnica de Catalunya. DF - Dinàmica de Fluids: formació d'estructures i aplicacions geofísiques
- Subjects
Ones ,010504 meteorology & atmospheric sciences ,lcsh:Dynamic and structural geology ,Surf zone ,Double sandbar systems ,010502 geochemistry & geophysics ,01 natural sciences ,Linear stability analysis ,lcsh:QE500-639.5 ,Beach erosion ,Conservation of mass ,Geomorphology ,Seabed ,0105 earth and related environmental sciences ,Earth-Surface Processes ,Shore ,geography ,geography.geographical_feature_category ,Morphodynamic stability of double-barred beaches ,Física [Àrees temàtiques de la UPC] ,Shoal ,Sand bars ,Amplitude ,Geophysics ,Waves ,Submarine pipeline ,Sediment transport ,Geology ,Platges -- Erosió - Abstract
Double sandbar systems often characterize the surf zone of wave-dominated beaches and display a variety of poorly explained spatial configurations. Here, we explore the morphodynamic stability of double-barred beaches using a model based on linear stability analysis. Surf zone hydrodynamics are described by coupling depth and wave-averaged conservation of mass and momentum with the wave energy and phase equations, including roller dynamics. A simplified sediment transport formulation relates flow to seabed changes. Under normal wave incidence, an alongshore uniform coast with a cross-shore profile characterized by the presence of two sandbars can be unstable, thereby resulting in the development of crescentic and/or rip channel patterns. Our study demonstrates that sandbar coupling can be either in phase (highs and lows of both sandbars are at the same alongshore position) or out of phase (highs and lows of one sandbar correspond to lows and highs of the other sandbar). In line with observations, results of simulations show a large variability in the possible emerging bottom patterns. Our analysis indicates that modes of which the amplitude of the inner sandbar perturbation is larger than that of the outer sandbar are dominant for large height–depth differences between the two sandbar crests and small offshore wave heights. Patterns related to the outer sandbar dominate for small values of the difference in sandbar depth. For intermediate differences between the two sandbar depths, patterns on both longshore bars appear to be fully coupled (similar growth rates and strongly correlated pattern shapes). For relatively large waves and large depth over the outer sandbar, patterns can also develop close to the shoreline and/or inner surf zone together with patterns in the inner or outer sandbar.
- Published
- 2020
8. Sensitivity of tidal motion in well-mixed estuaries to cross-sectional shape, deepening, and sea level rise
- Author
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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 ,Idealised model ,Resonance ,Physics::Fluid Dynamics ,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.
- Published
- 2015
9. Understanding coastal morphodynamic patterns from depth-averaged sediment concentration
- Author
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Ribas, Francesca, Falques, Albert, De Swart, Huib E., Dodd, Nicholas, Garnier, Roland, Calvete, Daniel, Sub Physical Oceanography, Dep Natuurkunde, Marine and Atmospheric Research, Universitat Politècnica de Catalunya. Departament de Física, and Universitat Politècnica de Catalunya. DF - Dinàmica No Lineal de Fluids
- Subjects
Sediment transport ,Sand bars ,BARRIER-ISLAND EVOLUTION ,TRANSVERSE BARS ,Platges -- Aspectes ambientals ,Física [Àrees temàtiques de la UPC] ,MIDDLE ATLANTIC SHELF ,SOUTHERN NORTH-SEA ,SELF-ORGANIZATION ,self-organization ,CONNECTED SAND RIDGES ,coastal morphodynamic patterns ,sand ridges ,INNER SHELF ,beach cusps ,BEACH CUSP FORMATION ,sediment transport coastal morphodynamic patterns nearshore sand bars beach cusps sand ridges self-organization ,PART 1 ,nearshore sandbars ,MORPHOLOGICAL RESPONSE - Abstract
This review highlights the important role of the depth-averaged sediment concentration (DASC) to understand the formation of a number of coastal morphodynamic features that have an alongshore rhythmic pattern: beach cusps, surf zone transverse and crescentic bars, and shoreface-connected sand ridges. We present a formulation and methodology, based on the knowledge of the DASC (which equals the sediment load divided by the water depth), that has been successfully used to understand the characteristics of these features. These sand bodies, relevant for coastal engineering and other disciplines, are located in different parts of the coastal zone and are characterized by different spatial and temporal scales, but the same technique can be used to understand them. Since the sand bodies occur in the presence of depth-averaged currents, the sediment transport approximately equals a sediment load times the current. Moreover, it is assumed that waves essentially mobilize the sediment, and the current increases this mobilization and advects the sediment. In such conditions, knowing the spatial distribution of the DASC and the depth-averaged currents induced by the forcing (waves, wind, and pressure gradients) over the patterns allows inferring the convergence/divergence of sediment transport. Deposition (erosion) occurs where the current flows from areas of high to low (low to high) values of DASC. The formulation and methodology are especially useful to understand the positive feedback mechanisms between flow and morphology leading to the formation of those morphological features, but the physical mechanisms for their migration, their finite-amplitude behavior and their decay can also be explored.
- Published
- 2015
10. Thickness-Weighted Averaging in Tidal Estuaries and the Vertical Distribution of the Eulerian Residual Transport.
- Author
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Klingbeil, Knut, Becherer, Johannes, Schulz, Elisabeth, de Swart, Huib E., Schuttelaars, Henk M., Valle-Levinson, Arnoldo, and Burchard, Hans
- Subjects
ESTUARIES ,TIDAL currents ,SEDIMENT transport ,ARITHMETIC mean - Abstract
This paper presents thickness-weighted averaging (TWA) in generalized vertical coordinates as a unified framework for a variety of existing tidal-averaging concepts in seas and estuaries. Vertical profiles of resulting residual quantities depend on the specific vertical coordinate, which is held fixed during the averaging process. This dependence is demonstrated through the application to one-dimensional analytical tidal flow with sediment transport, to field observations from a tidal channel, and to model results from a two-dimensional estuary. The use of different coordinate systems provides complementary views on the residual dynamics and stresses the importance of a correct interpretation of residual quantities obtained by tidal averaging. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
11. 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
12. Effect of sea level rise and tidal current variation on the long-term evolution of offshore tidal sand ridges.
- Author
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Yuan, Bing and de Swart, Huib E.
- Subjects
- *
ABSOLUTE sea level change , *TIDAL currents , *SAND waves , *CONTINENTAL shelf , *SEDIMENT transport - Abstract
Tidal sand ridges are large-scale bedforms that occur in the offshore area of shelf seas. They evolve on a time scale of centuries due to tide-topography interactions while being further shaped by wind waves. During their evolution, ridges are also affected by changes in sea level, strength and direction of the tidal current. According to their present-day behavior, ridges are classified as ‘active’ (sand transport everywhere), ‘quasi-active’ (sand transport only on parts of the ridges) and ‘inactive’ (no sand transport anywhere). Using a nonlinear morphodynamic model, the present study extends earlier work by investigating the effect of sea level rise and changes in the amplitude and principal direction of the tidal current on the growth time and height of active tidal sand ridges. Besides, the role of sea level rise and tidal current variation in the presence of quasi-active/inactive ridges is explored. Two specific settings are considered, which are characteristic for the Dutch Banks in the North Sea and for sand ridges in the Celtic Sea. The time range considered here is less than 20,000 years, roughly the period from the Last Glacial Maximum to the present. Generally active tidal sand ridges occur if the tidal current amplitude is larger than 0.5 m/s. For these ridges, with increasing rates of sea level rise, their growth time becomes longer, and the root mean square height keeps on increasing. A smaller initial tidal current amplitude gives rise to a larger growth time, while changes in the principal current direction have a minor effect on the characteristics of the ridges. On the considered time scale, assuming a constant wave climate, quasi-active tidal sand ridges occur mainly as a result of a decreasing tidal current amplitude such that the effective velocity (in the sense of stirring sand) becomes smaller than the critical velocity for sand erosion. The ridges further become inactive on a time scale that depends inversely on the rate of sea level rise. Modeled ridges are compared with observed ridges. Similarities are found and quantitative differences are explained. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
13. 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
14. Long bed waves in tidal seas: an idealized model.
- Author
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Blondeaux, Paolo, De Swart, Huib E., and Vittori, And Giovanna
- Subjects
TIDAL currents ,OCEAN currents ,SEDIMENT transport ,SEDIMENTATION & deposition ,EQUATIONS - Abstract
An idealized model is proposed to explain the appearance of the long bed waves that have been recently observed in shallow tidal seas. The model assumes that these bedforms grow due to tide-topography interaction. The water motion is described by means of the depth-averaged shallow water equations and the bottom evolution is governed by conservation of sediment mass. The sediment transport formulation includes a critical bottom stress below which no sediment moves. Also, anisotropic sediment transport, due to local bottom slopes in the longitudinal and transverse directions, is taken into account. A linear stability analysis of the flat bottom configuration reveals that different bottom patterns can emerge. In accordance with previous analyses, for strong tidal currents, the fastest growing modes are sand banks. However, if the tidal currents are elliptical and the maximum bottom stress is just above its threshold value for the initiation of sediment motion, the model shows the presence of further growing modes which resemble the long bed waves observed in the field. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
15. Effect of advective and diffusive sediment transport on the formation of local and global bottom patterns in tidal embayments.
- Author
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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
16. 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
17. 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
18. On the physics behind coastal morphodynamic patterns
- Author
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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
19. Effects of navigational works on morphological changes in the bar area of the Yangtze Estuary
- Author
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Jiang, Chenjuan, Li, Jiufa, and de Swart, Huib E.
- Subjects
- *
GEOMORPHOLOGY , *RIVER channels , *BATHYMETRIC maps , *HYDRODYNAMICS , *FLOOD control channels , *SEDIMENTATION & deposition - Abstract
Abstract: To improve navigability of the major access channel into Shanghai Harbor, a large-scale Deep Waterway Project was carried out in the North Passage (NP) of the Yangtze Estuary. In this paper, we investigate how the navigational works affected morphological changes of this channel, as well as those of the adjacent North Channel (NC), Hengsha East Shoal (HES), Jiuduansha Shoal (JDS), and the South Passage (SP). Morphological changes were assessed by analyzing digitized bathymetric data of this area prior to and after execution of the engineering works. The qualitative relations between these changes, along with the hydrodynamic changes as a result of the construction of engineering works, were subsequently investigated. The results reveal that the construction of training walls, groins and jetties resulted in decreased ebb transport in the upper reach of the NP and increased ebb transport in the upper reach of the SP. In turn, this led to intensive upstream erosion with large amounts of sediment transported seaward in the SP and associated sedimentation in the downstream area. At the same time, intense siltation occurred in the upper reach of the NP, while the main channel of the NP mainly experienced erosion caused by the construction of training walls and groins that concentrated ebb flow in the main channel. The waterway deepened significantly in previously shallow areas. Small tidal channels in the HES, which used to connect the NP and the NC, were cut off by the northern training wall. Consequently, residual flow in the middle reach of the NC flowed directly toward the northern bank of the HES, leading to local erosion. Flow obstruction by the southern training wall reduced the upstream propagation of the flood tide in the SP. As a result, a collection of small flood channels evolved under the flushing action of flood currents in the JDS, preventing the natural trend of horizontal extension of the JDS. However, the flow obstruction enhanced the vertical accretion of the JDS. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
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