"uuid","repository link","title","author","contributor","publication year","abstract","subject topic","language","publication type","publisher","isbn","issn","patent","patent status","bibliographic note","access restriction","embargo date","faculty","department","research group","programme","project","coordinates"
"uuid:8bd55ce1-adc7-486d-9bfa-7aa7b929bbe3","http://resolver.tudelft.nl/uuid:8bd55ce1-adc7-486d-9bfa-7aa7b929bbe3","Sand-Mud Morphodynamics","Colina Alonso, A. (TU Delft Coastal Engineering)","Wang, Zhengbing (promotor); van Maren, D.S. (promotor); Delft University of Technology (degree granting institution)","2024","The world’s coasts and deltas offer a multitude of valuable ecosystem services, providing safety against flooding and economic benefits. Many of these systems are, however, under pressure by climate change and increasing human activities. Protecting these systems and preservation of their multiple functions requires a thorough understanding of their morphodynamic behaviour. The sediment bed in many coastal systems worldwide is composed of two sediment types: sand and mud. While most previous research focused on the individual sediment dynamics of sand and mud, little is still known about how combined sand-mud morphodynamics differs from the sum of individual sediment fractions. In order to assess the impacts of anthropogenic interventions and climate change, we thus need to better understand sand-mud morphodynamics.
This research aims to improve the understanding of large-scale morphodynamics in sandmud tidal systems. This is done by investigating processes related to long-term deposition, sediment supply, sand-mud interaction, and segregation of sand and mud. We focus on generic idealized cases, as well as on case studies in the Wadden Sea — an example of a heavily-impacted system whose existence is threatened by sea level rise (SLR). Unique long-term data sets of its hydrodynamics, bathymetry and sediment composition are available, making this an excellent area to study the morphological responses to human interventions in detail, and to improve our understanding of sand-mud morphodynamics.
Analysis of the morphological evolution after a closure in the Western Dutch Wadden Sea (Chapter 2) illustrates the importance of distinguishing between the response of sandy and muddy sediments when analyzing the morphodynamic impact of an intervention. Our findings reveal that sand and mud respond on different temporal and spatial scales. Moreover, the results show that the contribution of mud to the total infilling was much larger than the average mud content in the top layer of the bed, because mud preferentially deposits in areas with high net sedimentation rates. This demonstrates that the contribution of sediment types to morphological change is not necessarily reflected by the spatial bed composition.
Up to now, the availability of mud to the Wadden Sea was poorly known, while we know that this availability is crucial for predicting the response to future climate change. Therefore, a first system-wide mud budget of the Wadden Sea has been developed (Chapter 3), revealing a nearly closed balance between the sources and the sinks. This observation implies that disturbing the mud balance at one location will impact downdrift areas. Anthropogenic sediment extraction provides the second largest sink, even surpassing salt marsh deposition. Field data suggest that a mud deficit already exists in some areas of the Wadden Sea, which will only become more pronounced with increased SLR rates. Mud is thus a finite resource similar to sand, and should be treated as such in sediment management strategies. Furthermore, local interventions may have consequences in downdrift areas, stressing the need for a cross-bordering perspective.
The influence of small-scale sand-mud interaction on large-scale modeled morphodynamic development has been studied by implementing two abiotic interactions (erosion interaction and roughness interaction) in a process-based model (Chapter 4). Model output was converted into metrics that describe the macro-scale configuration of the modeled systems, allowing a quantitative comparison of scenarios. The results demonstrate that sand-mud interaction can significantly impact tidal basin evolution, especially having a large influence on the intertidal flat shape, size and composition.
Lastly, we have seen that the mud content of the sediment bed in tidal systems is often bimodally distributed, indicating a preferential sand-mud segregation (Chapter 5). Bimodality represents the existence of two stable equilibrium conditions, which result from sediment deposition processes (and not erosion processes), and can be expected for a large range of suspended sediment concentrations in sand-mud systems. In order to correctly reproduce this bimodal character in process-based models, and therefore correctly modeling the bed sediment composition, one must account for erosion interaction in the model set-up — despite the role of deposition as a driving mechanism.
In conclusion, this dissertation illustrates the importance of a sand-mud perspective in morphodynamic studies, considering the contribution of both sediment types to the morphodynamic development as well as their interactions. We have seen that advancing our understanding of sand-mud morphodynamics requires combined data-based and modeling approaches, adopting a system-wide perspective, and considering the interactions between the various spatial and temporal scales. Morphological metrics, such as the ones that have been presented, are essential for the evaluation and comparison of model results and coastal morphology worldwide. Enabling successful and sustainable management of coasts and deltas will require further increasing our understanding of sand-mud morphodynamics through additional measurements and modeling studies. Developing a system understanding should be at the heart of all of these studies.","sand-mud; morphodynamics; tidal basins; Wadden Sea; numerical modeling","en","doctoral thesis","","78-94-6366-816-3","","","","","","","","","Coastal Engineering","","",""
"uuid:e0759412-1437-4585-8227-5a2c1ae92981","http://resolver.tudelft.nl/uuid:e0759412-1437-4585-8227-5a2c1ae92981","Modelling and analysis of the horizontal configuration of tidal fences in barrages","Verbeek, Merel C. (TU Delft Environmental Fluid Mechanics); Talstra, H. (Svašek Hydraulics); Labeur, R.J. (TU Delft Environmental Fluid Mechanics); Uijttewaal, W.S.J. (TU Delft Environmental Fluid Mechanics)","","2024","Tidal stream turbines are becoming an affordable option for harvesting sustainable energy in coastal areas. They can be retrofitted in barrages, providing an integral solution for flood protection and emission-free power generation, within environmental constraints. To optimize the turbine-barrage configuration with respect to these objectives, simulation tools are needed to predict the efficiency of the turbines as well as their impact on the adjacent tidal system. These tools should be based on an accurate representation of the underlying flow processes, which cover a wide range of spatial scales — from meters at the barrage and turbines to tenths of kilometers in the tidal basin. This article presents the development of such a tool by linking an analytical model for turbine fences in barrage gates to a regional flow model. The turbine model is validated with experimental data, and data from a thoroughly monitored tidal energy pilot project. Simulations reveal how clustering the turbines in small arrays can increase their efficiency, owing to array blockage effects, with only little effect on the tidal exchange. We also demonstrate the potential of using turbine fences to manipulate the tidal jet, issued from the barrage, with benefits for coastal — and wildlife protection in the basin. The presented research helps understanding how turbine fences in barrages can be configured with high energy yield and calculated impact to the environment.","Modelling; Sub-grid calculation; Tidal barrage; Tidal basin hydrodynamics; Tidal fences","en","journal article","","","","","","","","","","","Environmental Fluid Mechanics","","",""
"uuid:c89d09f0-22d8-4120-8e27-5f2524a76eee","http://resolver.tudelft.nl/uuid:c89d09f0-22d8-4120-8e27-5f2524a76eee","Adaptation timescales of estuarine systems to human interventions","van Maren, D.S. (TU Delft Environmental Fluid Mechanics; East China Normal Univeristy; Deltares); Colina Alonso, A. (TU Delft Coastal Engineering; Deltares); Engels, A. (Niedersächsischer Landesbetrieb für Wasserwirtschaft); Vandenbruwaene, W. (Flanders Hydraulics Research); de Vet, P.L.M. (TU Delft Coastal Engineering; Deltares); Vroom, J. (Deltares); Wang, Zhengbing (TU Delft Coastal Engineering)","","2023","Many estuaries and tidal basins are strongly influenced by various human interventions (land reclamations, infrastructure development, channel deepening, dredging and disposal of sediments). Such interventions lead to a range of hydrodynamic and morphological responses (a changing channel depth, tidal amplitude and/or suspended sediment concentration). The response time of a system to interventions is determined by the processes driving this change, the size of the system, and the magnitude of the intervention. A quantitative understanding of the response time to an intervention therefore provides important insight into the processes driving the response. In this paper we develop and apply a methodology to estimate the response timescales of human interventions using available morphological and hydraulic data. Fitting an exponential decay function to data with sufficient temporal resolution yields an adaptation timescale (and equilibrium value) of the tidal range and deposited sediment volumes. The method has been applied in the Dutch Wadden Sea, where two large basins were reclaimed and where long-term and detailed bathymetric maps are available. Exponential fitting the morphological data revealed that closure of a very large part of a tidal basin in the Wadden Sea initially led to internal redistribution and import of coarse and fine sediments, and was followed by a phase of extensive redistribution while only fine-grained sediments are imported. Closure of a smaller part of a smaller basin led to shorter response timescales, and these response timescales are also more sensitive to rising mean sea levels or high waters. The method has also been applied to tidal water level observations in the Scheldt and Ems estuaries. Exponential fits to tidal data reveal that adaptation timescales are shortest at the landward limit of dredging. The adaptation time increases in the landward direction because of retrogressive erosion (Scheldt) or lowering of the hydraulic roughness (Ems). The seaward increase in adaptation time is related to the seaward widening of both systems.","human interventions; morphological adaption; response timescales; estuaries; tidal basins","en","journal article","","","","","","","","","","","Environmental Fluid Mechanics","","",""
"uuid:7e34bc5c-fc0e-4001-8dfb-2fe93191d4e2","http://resolver.tudelft.nl/uuid:7e34bc5c-fc0e-4001-8dfb-2fe93191d4e2","Morphodynamic Modeling of Tidal Basins: The Role of Sand-Mud Interaction","Colina Alonso, A. (TU Delft Coastal Engineering; Deltares); van Maren, D.S. (TU Delft Environmental Fluid Mechanics; Deltares; East China Normal University); van Weerdenburg, R.J.A. (Deltares); Huismans, Y. (TU Delft Coastal Engineering; Deltares); Wang, Zhengbing (TU Delft Coastal Engineering; Deltares)","","2023","The morphology of tide-dominated systems is progressively influenced by human activities and climate change. Quantitative approaches aiming at understanding or forecasting the effects of interventions and climate change are often aggregated, thereby simplifying or schematizing the investigated area. In this work, we advance on the knowledge of sediment transport processes shaping tidal systems and on methodologies translating schematized model output into physically realistic variables. In terms of improved physics, we systematically evaluate the influence of sand-mud interaction processes. Most tidal systems are shaped by a mixture of sand and mud. Morphological models typically compute transport of sand and mud independently, despite studies clearly demonstrating that their physical behavior is mutually dependent. We investigate the effects of two interaction mechanisms (erosion interaction and roughness interaction, applied with varying mud erodibility) with a schematized process-based morphodynamic model. We convert model output into metrics that describe the meso-scale configuration of the modeled systems, allowing a quantitative comparison of scenarios. Modeled patterns and intertidal flat shape, size and composition widely vary with mud erodibility settings, but equally depend on the evaluated sand-mud interaction mechanisms (with erosion interaction having a larger effect than roughness interaction). Sand-mud interaction thus needs to be accounted for from a physical point of view, but also to improve predictions of tidal basin evolution models, particularly the (bimodally distributed) sediment composition of intertidal flats.","Delft3D; modeling; morphodynamics; morphological evolution; sand-mud interaction; tidal basins","en","journal article","","","","","","","","","","","Coastal Engineering","","",""
"uuid:a18267d7-1894-40e7-9997-19154b2f525c","http://resolver.tudelft.nl/uuid:a18267d7-1894-40e7-9997-19154b2f525c","Reclamation of Tidal Flats Within Tidal Basins Alters Centennial Morphodynamic Adaptation to Sea-Level Rise","Guo, Leicheng (Shanghai Estuarine and Coastal Science Research Center); Zhu, C. (TU Delft Coastal Engineering; Shanghai Estuarine and Coastal Science Research Center); Xu, Fan (Shanghai Estuarine and Coastal Science Research Center); Xie, Weiming (Shanghai Estuarine and Coastal Science Research Center); van der Wegen, Mick (IHE Delft Institute for Water Education; Deltares); Townend, Ian (University of Southampton); Wang, Zhengbing (TU Delft Coastal Engineering; Deltares); He, Qing (Shanghai Estuarine and Coastal Science Research Center)","","2022","Reclamation of low-lying tidal flats and floodplains adjacent to present shorelines has been implemented worldwide for both coastal defense and development. While it is technically feasible to monitor the short-term impact of tidal flat embankments, it is challenging to identify long-term and cumulative morphodynamic impact, particularly considering centennial sea-level rise (SLR). In this study, we construct a process-based hydro-morphodynamic model for a schematized tidal basin and examine its morphodynamic evolution under the combined influence of SLR and tidal flat embankments. We see that rising sea levels lead to inundation of low-lying floodplains just above high water, creating new intertidal flats that mitigate the drowning impact of SLR. This mitigation effect is lost if the low-lying floodplains and tidal flats are reclaimed, preventing any shoreline migration under SLR. Removing a large portion of intertidal flats within the tidal basin induces significant changes in basin hypsometry and potentially, a reversal of flood/ebb dominance. The resulting hydro-morphodynamic impact of large-scale tidal flat embankment is more significant than SLR at a centennial time scale. This suggests a need for much greater management awareness regarding the cumulative impact of human activities. These findings imply that allowing lateral shoreline migration under SLR sustains tidal basin's inherent morphodynamic buffering capacity, whereas reclaiming tidal flats significantly alters hydro-morphodynamic adaptation at the decadal to centennial time scales. It highlights the importance of conserving low-lying floodplains and tidal flats in tide-dominated systems to counteract the drowning impact of SLR.","embankment; morphodynamic modeling; sea-level rise; tidal basin","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2022-12-17","","","Coastal Engineering","","",""
"uuid:831ef593-b474-4678-9cb7-5cdafd91f111","http://resolver.tudelft.nl/uuid:831ef593-b474-4678-9cb7-5cdafd91f111","The Existence and Origin of Multiple Equilibria in Sand-Mud Sediment Beds","Colina Alonso, A. (TU Delft Coastal Engineering; Deltares); van Maren, D.S. (TU Delft Environmental Fluid Mechanics; Deltares; Shanghai Estuarine and Coastal Science Research Center); Herman, P.M.J. (TU Delft Environmental Fluid Mechanics; Deltares); van Weerdenburg, R.J.A. (Deltares); Huismans, Y. (TU Delft Coastal Engineering; Deltares); Holthuijsen, S. J. (NIOZ Royal Netherlands Institute for Sea Research; Waardenburg Ecology); Govers, L. L. (NIOZ Royal Netherlands Institute for Sea Research; University Medical Center Groningen); Bijleveld, A. I. (NIOZ Royal Netherlands Institute for Sea Research); Wang, Zhengbing (TU Delft Coastal Engineering; Deltares)","","2022","The sediment composition of the seabed governs its mobility, hence determining sediment transport and morphological evolution of estuaries and tidal basins. Bed sediments often consist of mixtures of sand and mud, with spatial gradients in the sand/mud content. This study aims at increasing the understanding of processes driving the sediment composition in tidal basins, focusing on depositional processes. We show that bed sediments in the Wadden Sea tend to be either mud-dominated or sand-dominated, resulting in a bimodal distribution of the mud content where the two modes represent equilibrium conditions. The equilibria depend primarily on the sediment deposition fluxes, with bimodality originating from the dependence of suspended sand/mud concentrations on the local bed composition. Our analysis shows that bimodality is a phenomenon that is not only specific for the Wadden Sea; it can be expected for a wide range of suspended sediment concentrations and thus also in other systems worldwide.","bed composition; morphodynamics; sand-mud; sand-mud segregation; tidal basins; Wadden sea","en","journal article","","","","","","","","","","","Coastal Engineering","","",""
"uuid:fc23b78b-1f57-449d-9158-49b8e6bf1d53","http://resolver.tudelft.nl/uuid:fc23b78b-1f57-449d-9158-49b8e6bf1d53","Coastal Dynamics","Bosboom, J. (TU Delft Coastal Engineering); Stive, M.J.F. (TU Delft Coastal Engineering)","","2021","This textbook on Coastal Dynamics focuses on the interrelation between physical wave, flow and sediment transport phenomena and the resulting morphodynamics of a wide variety of coastal systems. The textbook is unique in that it explicitly connects the dynamics of open coasts and tidal basins; not only is the interaction between open coasts and tidal basins of basic importance for the evolution of most coastal systems, but describing the similarities between their physical processes is highly instructive as well. This textbook emphasizes these similarities to the benefit of understanding shared processes such as nonlinearities in flow and sediment transport. Some prior knowledge with respect to the dynamics of flow, waves and sediment transport is recommended.","coasts; tidal basins; waves; tides; sediment","en","book","TU Delft OPEN Publishing","978-94-6366-370-0","","","","","","","","","Coastal Engineering","","",""
"uuid:1015fbeb-5d11-4a71-96cb-7a49571687e1","http://resolver.tudelft.nl/uuid:1015fbeb-5d11-4a71-96cb-7a49571687e1","Morphodynamic Equilibria in Double-Inlet Systems: Existence and Stability","Deng, X. (TU Delft Mathematical Physics); Meerman, C. (Universiteit Leiden); Boelens, T. (Universiteit Gent); De Mulder, T. (Universiteit Gent); Salles, P. (Universidad Nacional Autónoma de México); Schuttelaars, H.M. (TU Delft Mathematical Physics)","","2021","The existence of morphodynamic equilibria of double-inlet systems is investigated using a cross-sectionally averaged morphodynamic model. The number of possible equilibria and their stability strongly depend on the forcing conditions and geometry considered. This is illustrated by considering a rectangular double-inlet system forced by M2 tidal constituents only. Depending on the M2 amplitudes and phases at both entrances, no equilibrium, one equilibrium or multiple morphodynamic equilibria may exist. In case no equilibrium is found, the minimum water depth becomes zero somewhere in the system, reducing the double-inlet system to two single-inlet systems. In the other cases, the location of the minimum water depth and the direction of the tidally-averaged sediment transport, as well as their actual values, depend strongly on the M2 tidal characteristics. Such parameter sensitivity is also observed when including the residual and M4 forcing contributions to the water motion, and when allowing for width variations. This suggests that, when considering a specific system, the number and stability of morphodynamic equilibria, as well as the characteristics of these quantities, can only be assessed by investigating that specific system in detail. As an example, the Marsdiep-Vlie inlet system in the Dutch Wadden Sea is considered. It is found that, by using parameter values and a geometry characteristic for this system, the water motion and bathymetry in morphodynamic equilibrium are qualitatively reproduced. Also the direction and order of magnitude of the tidally-averaged suspended sediment transport compare well with those obtained from a high-complexity numerical model.","bifurcations; double inlet systems; morphodynamic equilibria; process-based models; tidal basins","en","journal article","","","","","","","","","","","Mathematical Physics","","",""
"uuid:cf351f80-caca-482c-985a-2fb14480ae40","http://resolver.tudelft.nl/uuid:cf351f80-caca-482c-985a-2fb14480ae40","The contribution of sand and mud to infilling of tidal basins in response to a closure dam","Colina Alonso, A. (TU Delft Coastal Engineering; Deltares); van Maren, D.S. (TU Delft Environmental Fluid Mechanics; Deltares; East China Normal University); Elias, E. P.L. (Deltares); Holthuijsen, S. J. (NIOZ Royal Netherlands Institute for Sea Research); Wang, Zhengbing (TU Delft Coastal Engineering; Deltares)","","2021","Human interventions and climate change can heavily influence the large-scale morphological development of tidal basins. This has implications on sediment management strategies, as well as ecological and recreational purposes. Examples of heavily impacted tidal basins are those in the Western Dutch Wadden Sea. The closure of a large sub-basin in 1932 triggered a shift in the sediment budgets of the remaining basins, leading to sediment infilling that is still ongoing. This paper presents a quantitative analysis of the post-closure sediment volumes, differentiating between sand and mud. Analysis of historical sediment composition data combined with bathymetry data revealed that the intervention caused a redistribution of sand and mud sedimentation. The responses of both sediment types differ spatially and temporally. The total infilling of the basins over the last century was substantially caused by mud (~32%, which is much larger than the average mud content in the bed). Initially, large mud volumes accreted in abandoned channels. At present, mud sedimentation along the mainland coast is still ongoing with nearly constant sedimentation rates over the past century, while the net import of sand significantly decreased over time and has been fluctuating around 0 over the last two decades. This research shows the importance of distinguishing between the response of sandy and muddy sediments when analysing the morphodynamic impact of an intervention, since they operate on different time and spatial scales. Sea level rise is currently a major threat for the existence of the Wadden Sea; its future fate will depend on whether the tidal flats are able to keep pace. Our results show that the supply of mud is sufficient to keep pace with the current sea level rise rates.","Closure dam; Human interference; Morphodynamics; Sediment budgets; Tidal basins; Wadden Sea","en","journal article","","","","","","","","","","","Coastal Engineering","","",""
"uuid:7722accf-fb33-4781-8348-c85810927b94","http://resolver.tudelft.nl/uuid:7722accf-fb33-4781-8348-c85810927b94","Morphodynamic adaptation of a tidal basin to centennial sea-level rise: The importance of lateral expansion","Guo, Leicheng (East China Normal University); Xu, Fan (East China Normal University); van der Wegen, Mick (IHE Delft Institute for Water Education; Deltares); Townend, Ian (University of Southampton); Wang, Zhengbing (TU Delft Coastal Engineering; East China Normal University; Deltares); He, Qing (East China Normal University)","","2021","Global climate changes have accelerated sea-level rise (SLR), which exacerbates the risks of coastal flooding and erosion. It is of practical interest to understand the long-term hydro-morphodynamic adaptation of coastal systems to SLR at a century time scale. In this work we use a numerical model to explore morphodynamic evolution of a schematized tidal basin in response to SLR of 0.25–2.0 m over 100 years with special emphasis on the impact of lateral basin expansion. Starting from a sloped initial bed, morphodynamic development of the system leads to the formation of alternating bars and meandering channels inside the tidal basin and an ebb-tidal delta extending seaward from the basin. Imposing rising sea level causes progressive inundation of the low-lying floodplains, found along the basin margins, inducing an increase in basin plain area and tidal prism, as well as intertidal area and storage volume. Although the overall channel-shoal structure persists under SLR, lateral shoreline expansion alters the basin hypsometry, leading to enhanced sediment export. The newly-submerged floodplains partly erode, supplying sediment to the system for spatial redistribution, hence buffering the impact of SLR. The vertical accretion rate of the tidal flats inside the tidal basin lags behind the rate of SLR. However, lateral shoreline migration under SLR creates new intertidal flats, compensating intertidal flat loss in the original basin. In contrast, a constrained tidal basin without low-lying floodplains is subject to profound drowning and tidal flat losses under SLR. Overall, the model results suggest that an unconstrained tidal system allowing lateral shoreline migration has buffering capacity for alleviating the drowning impact of SLR by evolving new intertidal areas, sediment redistribution and morphodynamic adjustment. These findings suggest that preserving tidal flats located along the margins of tidal basins (instead of reclaiming them) sustains the system's resilience to SLR.","Accommodation space; Morphodynamic modeling; Sea-level rise; Tidal basin","en","journal article","","","","","","Accepted Author Manuscript","","2022-07-12","","","Coastal Engineering","","",""
"uuid:0c9f7e18-af25-4fad-b50a-a43917c550d7","http://resolver.tudelft.nl/uuid:0c9f7e18-af25-4fad-b50a-a43917c550d7","Influence of geometrical variations on morphodynamic equilibria in short tidal basins","Meerman, C.J. (Universiteit Leiden); Rottschäffer, Vivi (Universiteit Leiden); Schuttelaars, H.M. (TU Delft Mathematical Physics)","","2019","The existence of cross-sectionally averaged morphodynamic equilibria of tidal inlets is investigated, using a cross-sectionally averaged model, and their sensitivity to variations of geometry, deposition parameter, frictional effects and advective sediment transport is analysed. Different geometries, from exponentially converging to exponentially diverging, are considered for inlets with lengths typical for the Dutch Wadden Sea. Standard continuation techniques are employed to numerically obtain morphodynamic equilibrium solutions, i.e. solutions for which the tidally averaged bed level does not change anymore. It is known that when the water motion at the entrance of the inlet is only forced by a M2 tidal constituent assuming the water level to be spatially uniform and only diffusive sediment transport is considered, the morphodynamic bed equilibrium has a constantly sloping profile for a rectangular inlet. We find that the bed profile in equilibrium becomes convex (concave) when we change the frictionless embayment geometry to a diverging (converging) geometry. Upon letting the deposition parameter depend on the depth, a more convex bed profile for all geometries considered is found. Including frictional effects in the momentum equation has a minor effect when only diffusion is considered, but the bed profile changes significantly when advection is included. When the tidal forcing of the sea surface elevation depends on a M4 tidal constituent as well, the morphodynamic equilibrium bed varies from very deep to shallow, depending on the relative phase. For a diverging inlet geometry, there are combinations of the relative phase and tidal basin length for which we show the existence of multiple equilibria. This implies that for these geometries, the cross-sectionally averaged bed profile in morphodynamic equilibrium can change significantly when the relative phase or the embayment length is changed. The magnitude of the perturbation necessary to actually evolve towards the other equilibrium and the time scale associated with this change can not be inferred from the analysis presented in this paper.","Idealised model; Morphodynamic equilibrium; Multiple equilibria; Sediment transport; Tidal basin","en","journal article","","","","","","","","","","","Mathematical Physics","","",""
"uuid:b867135c-0df5-439a-a0f7-702d4f67a593","http://resolver.tudelft.nl/uuid:b867135c-0df5-439a-a0f7-702d4f67a593","On the stability relations between tidal asymmetry and morphologies of tidal basins and estuaries","Zhou, Zeng; Coco, Giovanni (The University of Auckland); Townend, Ian (University of Southampton); Gong, Zheng; Wang, Zhengbing (TU Delft Coastal Engineering); Zhang, Changkuan","","2018","Simple stability relationships are practically useful to provide a rapid assessment of coastal and estuarine landforms in response to human interventions and long‐term climate change. In this contribution, we review a variety of simple stability relationships which are based on the analysis of tidal asymmetry (shortened to “TA”). Most of the existing TA‐based stability relationships are derived using the one‐dimensional tidal flow equations assuming a certain regular shape of the tidal channel cross‐sections. To facilitate analytical solutions, specific assumptions inevitably need to be made e.g. by linearising the friction term and dropping some negligible terms in the tidal flow equations. We find that three major types of TA‐based stability relationships have been proposed between three non‐dimensional channel geometric ratios (represented by the ratio of channel widths, ratio of wet surface areas and ratio of storage volumes) and the tide‐related parameter a/h (i.e. the ratio between tidal amplitude and mean water depth). Based on established geometric relations, we use these non‐dimensional ratios to re‐state the existing relationships so that they are directly comparable. Available datasets are further extended to examine theutility of these TA‐based relationships. Although a certain agreement is shown for these relationships, we also observe a large scatter of data points which are collected in different types of landscape, hydrodynamic and sedimentologic settings over the world. We discuss in detail the potential reasons for this large scatter and subsequently elaborate on the limited applicability of the various TA‐based stability relationships for practical use. We highlight the need to delve further into what constitutes equilibrium and what is needed to develop more robust measures to determine the morphological state of these systems.","tidal basins; estuarine morphologies; tidal asymmetry; stability relationships","en","journal article","","","","","","","","2019-04-01","","","Coastal Engineering","","",""
"uuid:5c00582e-6a20-4e70-8f8e-992d3fbd8076","http://resolver.tudelft.nl/uuid:5c00582e-6a20-4e70-8f8e-992d3fbd8076","Net sediment transport in tidal basins: quantifying the tidal barotropic mechanisms in a unified framework","Gatto, V.M. (TU Delft Coastal Engineering); van Prooijen, Bram (TU Delft Environmental Fluid Mechanics); Wang, Zhengbing (TU Delft Coastal Engineering)","","2017","Net sediment transport in tidal basins is a subtle imbalance between large fluxes produced by the flood/ebb alternation. The imbalance arises from several mechanisms of suspended transport. Lag effects and tidal asymmetries are regarded as dominant, but defined in different frames of reference (Lagrangian and Eulerian, respectively). A quantitative ranking of their effectiveness is therefore missing. Furthermore, although wind waves are recognized as crucial for tidal flats’ morphodynamics, a systematic analysis of the interaction with tidal mechanisms has not been carried out so far. We review the tide-induced barotropic mechanisms and discuss the shortcomings of their current classification for numerical
process-based models. Hence, we conceive a unified Eulerian framework accounting for wave-induced resuspension. A new methodology is proposed to decompose the sediment fluxes accordingly, which is applicable without needing (semi-) analytical approximations. The approach is tested with a one-dimensional model of the Vlie basin, Wadden Sea (The Netherlands). Results show that lag-driven transport is dominant for the finer fractions (silt and mud). In absence of waves, net sediment fluxes are landward and spatial (advective) lag effects are dominant. In presence of waves, sediment can be exported from the tidal flats and temporal (local) lag effects are dominant. Conversely, sand transport is dominated by the asymmetry of peak ebb/flood velocities. We show that the direction of lag-driven transport can be estimated by the gradient of hydrodynamic energy. In agreement with previous studies, our results support the conceptualization of tidal flats’ equilibrium as a simplified balance between tidal mechanisms and wave resuspension.","Wadden Sea; Settling lag; Tidal asymmetry; Residual transport; Tidal basins; Morphodynamics","en","journal article","","","","","","","","","","","Coastal Engineering","","",""
"uuid:dff70d1b-199f-406b-806e-03342e45c4da","http://resolver.tudelft.nl/uuid:dff70d1b-199f-406b-806e-03342e45c4da","Morphodynamic development and sediment budget of the Dutch Wadden Sea over the last century","Elias, E.P.L.; Van der Spek, A.J.F.; Wang, Z.B.; De Ronde, J.","","2012","The availability of nearly 100 years of bathymetric measurements allows the analysis of the morphodynamic evolution of the Dutch Wadden Sea under rising sea level and increasing human constraint. The historically observed roll-over mechanisms of landward barrier and coastline retreat cannot be sustained naturally due to numerous erosion control measures that have fixed the tidal basin and barrier dimensions. Nevertheless, the large continuous sedimentation in the tidal basins (nearly 600 million m3), the retained inlets and the similar channel-shoal characteristics of the basins during the observation period indicate that the Wadden Sea is resilient to anthropogenic influence, and can import sediment volumes even larger than those needed to compensate the present rate of sea-level rise. The largest sedimentation occurs in the Western Wadden Sea, where the influence of human intervention is dominant. The large infilling rates in closed-off channels, and along the basin shoreline, rather than a gradual increase in channel flat heights, render it likely that this sedimentation is primarily a response to the closure of the Zuiderzee and not an adaptation to sea-level rise. Most of the sediments were supplied by the ebb-tidal deltas. It is, however, unlikely that the sediment volume needed to reach a new equilibrium morphology in the Western Wadden Sea can be delivered by the remaining ebb-tidal deltas alone.","Wadden Sea; morphodynamics; tidal basins; ebb-tidal deltas; impact large-scale engineering works","en","conference paper","Netherlands Journal of Geosciences Foundation","","","","","","","2014-11-30","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:9e12cde6-e127-4e5a-aea5-e57fcb6b8a32","http://resolver.tudelft.nl/uuid:9e12cde6-e127-4e5a-aea5-e57fcb6b8a32","Long-term process-based morphological modeling of large tidal basins","Dastgheib, A.","Roelvink, J.A. (promotor)","2012","The morphology of tidal basins includes a wide range of features developing along different spatial and temporal scales. Examples are shoals, channels, banks, dunes and ripples. Coastal engineers use their engineering tools to answer questions on the processes governing the short term (< decades) development of these morphological features. Geologists apply their conceptual models and reconstruction methods to answer questions related to a much longer time scale (> centuries). This two-sided approach has left us with limited understanding of processes occurring on intermediate scales (> decades and < centuries), whereas the morphodynamics of these intermediate scales are of special concern to sustainable coastal zone management. This study is part of a collective effort to bridge the aforementioned gap by extending the use of coastal engineering tools (process-based models) to geological time scales to provide more understanding of the physical processes governing the long-term morphodynamic behavior of tidal basins. A fundamental question addressed is whether or not process-based models can reproduce trustworthy long-term developments. To answer this question the Dutch Waddenzee is chosen as a reference case. This study suggests that the question has a positive answer. By comparing model results with measured developments in the Waddenzee, this study shows that a process-based model can reproduce channel-shoal patterns and their long-term development qualitatively well. Modeled parameters such as area, volume and height of the inter-tidal flats obey the databased equilibrium equations. This study also demonstrates the models' ability to qualitatively assess the impact of large scale human intervention in a tidal basin. For example, the model is able to reproduce the change in tidal transport regime and the ensuing morphodynamic changes due to an extreme impact such as the closure of the Zuiderzee. Although the highly schematized simulations produced qualitatively good results, they also revealed the need for a better process description. As the first step to improve model performance a methodology was developed to account for sediment composition and distribution in the bed. In the next step different methodologies to schematize wave action for long-term morphological simulations were investigated. investigated the wave climate. Model results show that the chronology of wave conditions and the wave schematization approach have a limited effect. The outcome of long-term morphodynamic simulations with different wave and tidal conditions are in good agreement with conceptual models. For the reference case, model results revealed that the morphological impact of wind waves is not only important outside the inlet and at the ebb-tidal delta, but also within the tidal basin. A final conclusion is that adding methodologies for bed composition and wave schematization to the model of the Waddenzee area improved the hindcasting simulations qualitatively.","morphology; tidal basin; tidal inlet; ebb tidal delta; Delft3D; Process-based Modelling; Waddenzee; afsluitdijk; morphological factor; sediment mixture; morphological tide","en","doctoral thesis","CRC Press/Balkema","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:8b88ca00-045c-4541-b2d1-11605f76606c","http://resolver.tudelft.nl/uuid:8b88ca00-045c-4541-b2d1-11605f76606c","Assessment of the effects of the Zuider Sea closure on the hydrodynamics of the Wadden Sea inlets","Vroom, J.; Elias, E.; Lescinski, J.; Wang, Z.B.","","2012","Large hydrodynamic and morphodynamic changes have taken place in the western Dutch Wadden Sea due to the closure of the Zuider Sea in the early 1930s. Hydrodynamic simulations for three situations, viz. just before the closure, just after the closure and at present, have been carried out in order to investigate the hydrodynamic changes since the closure and to improve our understanding of the observed morphodynamic changes. The model results show a large increase in tidal range after the closure of the Zuider Sea. This increase continued to grow after the closure due to bathymetric change and sea level rise. The morphodynamic analysis focuses on the changed behavior of the ebb-tidal deltas of the Texel Inlet and the Vlie Inlet. Both ebb-tidal deltas have undergone a re-orientation in up drift direction. Two possible explanations based on the literature for this change are discussed with the help of the hydrodynamic simulations.","Wadden Sea; Zuider Sea; Delft3D modeling; tidal basins; basin area reduction; tidal asymmetry","en","conference paper","Coastal Engineering Research Council","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"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:88474bf9-2466-41cd-98f7-21cc8b51db03","http://resolver.tudelft.nl/uuid:88474bf9-2466-41cd-98f7-21cc8b51db03","Historical Morphological development of the Eastern Scheldt tidal basin (the Netherlands)","Eelkema, M.; Wang, Z.B.; Stive, M.J.F.","","2009","The Eastern Scheldt tidal basin has changed drastically in the past five centuries under the influence of both human interventions as well as extreme events. In 1530 A.D. a storm-surge inundated large parts in the landward end of the basin, and in the following four centuries local inhabitants reclaimed about as much land as was inundated in that storm. To investigate the effects of these processes on basin morphology, several different simplified geometries of the basin are used in order to gain insight into the evolution of the tidal currents over the centuries. From this model it appears that the large-scale inundations cause the basin to scour to greater depth. This in turn causes the ebb-tidal delta to grow, and causes the disappearance of the tidal watershed between the Eastern Scheldt and the Grevelingen tidal basins. Land reclamations have not been able to turn these trends around.","Tidal basin; Eastern Scheldt; Land reclamation; Inundation; Ebb-tidal delta; Tidal watershed","en","conference paper","World Scientific Publishing","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:f99c575b-b76b-4aa7-851d-0dca3d380759","http://resolver.tudelft.nl/uuid:f99c575b-b76b-4aa7-851d-0dca3d380759","Morphodynamic modelling of estuarine channel-shoal systems","Hibma, A.","De Vriend, H.J. (promotor)","2004","In this research, the initial formation and long-term evolution of channel-shoal patterns in schematised basins is simulated using a model based on the software package Delft3D. The resulting channel-shoal patterns are validated with field observations, among which the Western Scheldt estuary. This has proven that a complex model is able to simulate the emergence and evolution of nature-like patterns, on time scales from decades to centuries. Additionally, a comparison with other model types has given insight into the influence of different model assumptions and formulations and into the processes underlying the morphodynamic behaviour of channels and shoals in estuaries. Applying this new knowledge we are able to set up predictive models, which help us to manage our estuaries in a durable way, combining different model types and data, such that optimal use can be made of each research method.","morphology; estuaries; channel; shoal; tidal basin; numerical model","en","doctoral thesis","PrintPartners Ipskamp BV","","","","","","","","Civil Engineering and Geosciences","","","","",""
"uuid:fc9bcc67-48db-4763-a121-86c7656099e4","http://resolver.tudelft.nl/uuid:fc9bcc67-48db-4763-a121-86c7656099e4","Coastal inlets and tidal basins","De Vriend, H.J.; Dronkers, J.; Stive, M.J.F.; Van Dongeren, A.; Wang, J.H.","","2002","lecture note: Tidal inlets and their associated basins (lagoons) are a common feature of lowland coasts all around the world. A significant part ofthe world's coastlines is formed by barrier island coasts, and most other tidal coasts are interrupted by estuaries and lagoon inlets. These tidal systems play a crucial role in the sediment budget ofthe coastal zone and thus influence the long-term coastal evolution. From a morphological point of view, tidal inlets form highly dynamical systems, which are interlinked with the adjacent coast and the tidal basin or backbarrier area to which they give access. Often, the natural morphodynamic behaviour interferes with unnatural constraints (e.g. coastal defence works) and with the effects of human utilisation (e.g. sand mining). Estuaries and tidal lagoons attract a variety of human activities, such as navigation, recreation, fishing and aquaculture, economical activity in the border zone, sand mining, land reclamation and in some cases hydrocarbon mining. On the other hand, many estuaries and lagoons form the basis of highly valuable and sometimes unique ecosystems. They function as nursery grounds for many species and as resting and feeding grounds for many others. Hence human activities which affect the properties of such a system, or put the environmental functions otherwise at risk, may have important environmental implications. For the proper management of these systems, it is therefore most important to be able to predict the impacts of such activities. At a larger scale, a deficit of sediment in the backbarrier area, due to sea level rise, for instance, can have major effects on the sediment budget of the coastal zone. The outer deltas of the inlets seem to act as sediment buffers, but the ultimate source of the sediment which goes to the backbarrier area is the coast. Since long-term coastal zone management should include sediment management, the capability to predict the large-scale exchange of sediment is of great importance to ICZM (Integrated Coastal Zone Management). The inlets and their outer deltas play a key role in this exchange. These lectures intend to develop an insight into the physical functioning of coastal inlets and tidal basins, such that possible engineering inten/entions are executed from a sustainable, holistic and integrated management perspective. The emphasis will be on inlet and basin systems which are subject to a mixed tidal and wave forcing, with negligible fresh water runoff, typical examples being the Wadden Sea and the Zeeland inlets and basins. Foreign examples are typically barrier-inlet coasts, such as found abundantly along the east-coast of the USA. This implies that fresh and salt water dynamics are not of strong relevance, and that the morphodynamics of these systems are largely determined by the interaction between the coarser sediment (fine to medium sands) and the tide and wave induced water motions.","tidal inlet; tidal basin; waddenzee; collegediktaat wa5303","en","lecture notes","TU Delft, Section Hydraulic Engineering","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:84cfca88-c246-4aae-bfaf-6c2d03d005c4","http://resolver.tudelft.nl/uuid:84cfca88-c246-4aae-bfaf-6c2d03d005c4","Principles of Mixing in Tidal Basins in the Netherlands","Dronkers, J.; Zimmerman, J.T.F.","Rijkswaterstaat","1981","Some fundamental notions related to the flushing of tidal basins are reviewed and some important mixing mechanics are discussed. It is shown that the characteristics of mixing and flushing in tidal basins can be described in various but connected ways, introducing the concepts of time scales and dispersion coefficients. For some simple geometrical configurations formulas for the computation of time scales and dispersion coefficients are given. For complex-shaped tidal bas ins field data are necessary in order to obtain quantitative information on time scales, dispersion coefficients or on the contribution of different mixing processes. The theoretical topics dealt with in this paper are illustrated by field data collected in some tidal basins in the Netherlands.","tidal basins; mixing; dispersion","en","report","Rijkswaterstaat, Deltadienst","","","","","","","","","","","","",""