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The relationship between linearised 3D and 2DH models for tidally dominated shallow waters

Rozendaal, M.C. (author), Dijkstra, Y.M. (author), Schuttelaars, H.M. (author)

The water motion computed using 3D and 2DH models in tidally dominated shallow waters can, in some cases, differ significantly. In 2DH models, bed friction is typically parametrised in terms of the depth-averaged velocity, whereas in 3D models, typically the near-bed velocity is used. This difference causes the bed shear stress in 2DH models...

journal article 2024

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Estuarine Adjustment: Dependence of Salinity Delay on the Forcing Timescale and Magnitude

Dijkstra, Y.M. (author)

The salinity in estuaries continuously adapts to varying forcing for example, by discharge and tidal conditions. The changes in salinity lag behind the changes in forcing. Previous work has mostly related this delay to the adjustment time, which depends on an average background state of the estuary. Payo-Payo et al. (2022), https://doi.org/10...

journal article 2024

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Evolution of multi-annual and large-scale phytoplankton patterns in the Scheldt estuary: The disappearance of phytoplankton accumulation in the brackish region

Horemans, D.M.L. (author), Dijkstra, Y.M. (author), Tackx, Michèle (author), Meire, Patrick (author), Cox, Tom J.S. (author)

Estuaries often show regions in which Chlorophyll-a (Chl-a) accumulates. The location and magnitude corresponding to such accumulation result from a complex interplay between processes such as river flushing, salinity, nutrients, grazing on phytoplankton, and the light climate in the water column. An example is the multi-annual evolution of...

journal article 2023

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Multiscale Temporal Response of Salt Intrusion to Transient River and Ocean Forcing

Payo-Payo, Marta (author), Bricheno, Lucy M. (author), Dijkstra, Y.M. (author), Cheng, Weicong (author), Gong, Wenping (author), Amoudry, Laurent O. (author)

Salt intrusion in surface waters endangers freshwater availability, influences water quality, and affects estuarine ecosystem services with high economic and social values. Salt transport and the resulting salinity distributions result from the non-linear interactions between salt and water dynamics. Estuaries are often considered under ...

journal article 2022

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Turbidity maxima in estuarine networks: Dependence on fluvial sediment input and local deepening/narrowing with an exploratory model

Wang, Jinyang (author), Dijkstra, Y.M. (author), de Swart, Huib E. (author)

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...

journal article 2022

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Influence of Wind on Subtidal Salt Intrusion and Stratification in Well-Mixed and Partially Stratified Estuaries

Jongbloed, Hendrik (author), Schuttelaars, H.M. (author), Dijkstra, Y.M. (author), Donkers, Paul B. (author), Hoitink, Antonius J.F. (author)

An idealized width-averaged model is employed to study the influence of wind stress on subtidal salt intrusion and stratification in well-mixed and partially stratified estuaries. We show that even in mild conditions, wind forcing can influence the estuarine salinity structure in a substantial way. By studying the role of wind forcing on...

journal article 2022

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Mechanisms Controlling the Distribution of Net Water Transport in Estuarine Networks

Wang, Jinyang (author), Dijkstra, Y.M. (author), de Swart, Huib E. (author)

Net water transport (NWT) in estuaries is important for, for example, salt intrusion and sediment dynamics. While NWT is only determined by river runoff in single channels, in estuarine networks, it results from a complex interplay between tides and residual flows. This study aims to disentangle the various contributions of these physical...

journal article 2022

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Salt Transport Regimes Caused by Tidal and Subtidal Processes in Narrow Estuaries

Dijkstra, Y.M. (author), Schuttelaars, H.M. (author), Kranenburg, W.M. (author)

Tidally averaged transport of salt in estuaries is controlled by various subtidal and tidal processes. In this study, we show the relative importance of various subtidal and tidal transport processes in a width-averaged sense. This is done for a large range of forcing and geometric parameters, which describe well-mixed to salt wedge estuaries...

journal article 2022

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Adjustment and Extension of the Hansen and Rattray Estuarine Classification Diagram

Dijkstra, Y.M. (author), Schuttelaars, H.M. (author)

The classification diagram developed by Hansen and Rattray is one of the classic papers on classification of estuarine salinity dynamics. However, we found several inconsistencies in both their stratification–circulation and estuarine classification diagrams. These findings considerably change the interpretation of their work. Furthermore, while...

journal article 2021

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A unifying approach to subtidal salt intrusion modeling in tidal estuaries

Dijkstra, Y.M. (author), Schuttelaars, H.M. (author)

The salinity structure in estuaries is classically described in terms of the salinity structure as well mixed, partially mixed, or salt wedge. The existing knowledge about the processes that result in such salinity structures comes from highly idealized models that are restricted to either well-mixed and partially mixed cases or subtidal salt...

journal article 2021

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Seasonal Variations in Flocculation and Erosion Affecting the Large-Scale Suspended Sediment Distribution in the Scheldt Estuary: The Importance of Biotic Effects

Horemans, Dante M.L. (author), Dijkstra, Y.M. (author), Schuttelaars, H.M. (author), Sabbe, Koen (author), Vyverman, Wim (author), Meire, Patrick (author), Cox, Tom J.S. (author)

Many estuaries exhibit seasonality in the estuary-scale distribution of suspended particulate matter (SPM). This SPM distribution depends on various factors, including freshwater discharge, salinity intrusion, erodibility, and the ability of cohesive SPM to flocculate into larger aggregates. Various authors indicate that biotic factors, such...

journal article 2021

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Dependence of tides and river water transport in an estuarine network on river discharge, tidal forcing, geometry and sea level rise

Wang, Jinyang (author), de Swart, Huib E. (author), Dijkstra, Y.M. (author)

Estuaries are often characterised by a complex network of branching channels, in which the water motion is primarily driven by tides and fresh water discharge. For both scientific reasons and management purposes, it is important to gain more fundamental knowledge about the hydrodynamics in such networks, as well as their implications for...

journal article 2021

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Unraveling the essential effects of flocculation on large-scale sediment transport patterns in a tide-dominated estuary

Horemans, D.M.L. (author), Dijkstra, Y.M. (author), Schuttelaars, H.M. (author), Meire, Patrick (author), Cox, Tom J.S. (author)

Sediment transport in estuaries and the formation of estuarine turbidity maxima (ETM) highly depend on the ability of suspended particulate matter (SPM) to flocculate into larger aggregates. While most literature focuses on the small-scale impact of biological flocculants on the formation of larger aggregates, the influence of the...

journal article 2020

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Regime shifts in sediment concentrations in tide-dominated estuaries

Dijkstra, Y.M. (author)

Within estuaries one can often observe areas where the concentration of fine suspended sediments is higher than in the surrounding waters, called estuarine turbidity maxima (ETM). ETM play an important role in the natural and socio-economic value of estuaries. The suspended sediments can for example greatly diminish the value of the estuarine...

doctoral thesis 2019

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Modeling the Transition to High Sediment Concentrations as a Response to Channel Deepening in the Ems River Estuary

Dijkstra, Y.M. (author), Schuttelaars, H.M. (author), Schramkowski, G.P. (author), Brouwer, R.L. (author)

Many estuaries are strongly modified by human interventions, including substantive channel deepening. In the Ems River Estuary (Germany and Netherlands), channel deepening between the 1960s and early 2000s coincided with an increase in the maximum near-bed suspended sediment concentration from moderate (∼1 kg/m ³ ) to high (>10...

journal article 2019

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A Regime Shift From Low to High Sediment Concentrations in a Tide-Dominated Estuary

Dijkstra, Y.M. (author), Schuttelaars, H.M. (author), Schramkowski, G.P. (author)

Many estuaries are strongly deepened to improve navigation, with sometimes large and poorly understood consequences to suspended sediment dynamics. To improve understanding of such large changes, we study the Ems River Estuary, where a regime shift from low to high sediment concentrations was observed after deepening. The aim of this study is...

journal article 2019

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Can the Scheldt River Estuary become hyperturbid?: A model analysis of suspended sediment concentrations and transport in response to channel deepening

Dijkstra, Y.M. (author), Schuttelaars, H.M. (author), Schramkowski, G.P. (author)

We investigate the hypothesis by Winterwerp and Wang (Ocean Dyn 63:1279–1292, 2013) that channel deepening in the Scheldt River Estuary could lead to a large increase in suspended sediment concentrations, with subsequent severe consequences to primary production and navigation. To this end, we use an idealised model to investigate the long...

journal article 2019

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Factors Controlling Seasonal Phytoplankton Dynamics in the Delaware River Estuary: an Idealized Model Study

Dijkstra, Y.M. (author), Chant, Robert J. (author), Reinfelder, John R. (author)

Phytoplankton biomass in estuaries is controlled by complex biological and chemical processes that control growth and mortality, and physical processes that control transport and dilution. The effects of these processes on phytoplankton blooms were systematically analyzed, focusing on identifying the dominant controlling factors out of river...

journal article 2019

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The hyperturbid state of the water column in estuaries and rivers: The importance of hindered settling

Dijkstra, Y.M. (author), Schuttelaars, H.M. (author), Winterwerp, J.C. (author)

Over the last few decades, some estuaries have undergone a transition to a hyperturbid state, characterised by suspended sediment concentrations of several grammes per litre averaged over the water column. To improve our understanding of this transition and of naturally hyperturbid estuaries, we systematically identify the processes allowing...

journal article 2018

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Time Evolution of Estuarine Turbidity Maxima in Well-Mixed, Tidally Dominated Estuaries: The Role of Availability- and Erosion-Limited Conditions

Brouwer, R.L. (author), Schramkowski, G.P. (author), Dijkstra, Y.M. (author), Schuttelaars, H.M. (author)

Using an idealized width-averaged process-based model, the role of a mud pool on the bed and time-varying river discharge on the trapping of fine sediment is systematically investigated. For this purpose, a dynamically and physically motivated description of erodibility is presented, which relates the amount of sediment on the bed to the...

journal article 2018