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You searched for +publisher:"Delft University of Technology" +contributor:("Dijkstra, Yoeri"). Showing records 1 – 3 of 3 total matches.

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Delft University of Technology

1. Donkers, Paul (author). A theoretical study of the sub-tidal, width-averaged effects of wind stress in estuaries: Dynamics, stratification and salt intrusion.

Degree: 2020, Delft University of Technology

The goal of this thesis is to create a theoreticalmodel that captures the influence of wind on the horizontal and vertical salinity distribution in an estuary, as well as the dynamics that arise within the estuary. A secondary, numerical model, that uses fewer assumptions, will be developed and analysed. This serves to determine whether the implications from the theoretical model hold only because of all the assumptions that are made, or whether the results are equally valid when some of these assumptions are relaxed. The focus of this thesis is on gaining conceptual insight in estuaries subject to wind, rather than on obtaining a high accuracy in describing a specific estuary. This thesis is focused on steady-state solution in partially orwell mixed estuaries. Moreover, the dynamics and salinity averaged over the width of the estuary are considered, such that only dynamics in the vertical and along channel direction are modelled. Estuaries are subject to periodical variations forced by tides. The variation within a tidal period is not studied in this thesis, but the dynamics and salinity averaged over a tidal period are considered. The effects of tides or variation along the width of the estuary are not neglected from this model, but are incorporated in the parametrisation of the model instead. Advisors/Committee Members: Dijkstra, Yoeri (mentor), Schuttelaars, Henk (graduation committee), Delft University of Technology (degree granting institution).

Subjects/Keywords: estuary; bifurcation; wind; analytical; numerical

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Donkers, P. (. (2020). A theoretical study of the sub-tidal, width-averaged effects of wind stress in estuaries: Dynamics, stratification and salt intrusion. (Masters Thesis). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:1705a083-17c0-461c-b17c-231ec28f4860

Chicago Manual of Style (16th Edition):

Donkers, Paul (author). “A theoretical study of the sub-tidal, width-averaged effects of wind stress in estuaries: Dynamics, stratification and salt intrusion.” 2020. Masters Thesis, Delft University of Technology. Accessed October 21, 2020. http://resolver.tudelft.nl/uuid:1705a083-17c0-461c-b17c-231ec28f4860.

MLA Handbook (7th Edition):

Donkers, Paul (author). “A theoretical study of the sub-tidal, width-averaged effects of wind stress in estuaries: Dynamics, stratification and salt intrusion.” 2020. Web. 21 Oct 2020.

Vancouver:

Donkers P(. A theoretical study of the sub-tidal, width-averaged effects of wind stress in estuaries: Dynamics, stratification and salt intrusion. [Internet] [Masters thesis]. Delft University of Technology; 2020. [cited 2020 Oct 21]. Available from: http://resolver.tudelft.nl/uuid:1705a083-17c0-461c-b17c-231ec28f4860.

Council of Science Editors:

Donkers P(. A theoretical study of the sub-tidal, width-averaged effects of wind stress in estuaries: Dynamics, stratification and salt intrusion. [Masters Thesis]. Delft University of Technology; 2020. Available from: http://resolver.tudelft.nl/uuid:1705a083-17c0-461c-b17c-231ec28f4860


Delft University of Technology

2. Bouwman, Dennis (author). The influence of spring-neap cycles on sediment trapping in tide-dominated estuaries.

Degree: 2019, Delft University of Technology

Using an idealized width-averaged model, the influence of spring-neap cycles on the transport and trapping of suspended fine sediment in tide-dominated estuaries is investigated. To this end we introduce a multiple time scale expansion. This provides a mathematically sound argument for treating the fast ebb-flood cycle and the slow spring-neap variations as independent time scales. With this expansion, semi-analytical approximations of the water motion and suspended sediment concentrations can be found as functions of the spring-neap time scale. The advantage of this is that the transport of sediment is then investigated in a tidally-averaged sense using analytically obtained temporal dependencies and model simulations based on the conditions in 2005 of the Ems-Dollard estuary. We found that sediment import is strongly enhanced during spring tide and that a combination of vanishing import processes and sediment export due to river discharge resulted in a net export of sediment during neap tide. Furthermore the spring-neap varying deposition of fine sediment in a bottom pool on the river bed is investigated. We found that the time needed for the system to adjust to new equilibrium conditions can not be neglected within a spring-neap cycle as temporal lag effects are clearly visible in the dynamic behaviour of the bottom pool and suspended sediment concentrations. These temporal lag effects are sensitive to the choice of the parameter governing erosion. Assuming different values of the erosion parameter we have shown that the long-term characteristics of the bottom pool are sensitive to these temporal lag effects. Choosing a low value of the erosion parameter results in the presence of a bottom pool throughout the spring-neap cycle. With a high value of the erosion no bottom pool is formed at any time in the spring-neap cycle.

Computational Science and Engineering

Advisors/Committee Members: Schuttelaars, Henk (mentor), Dijkstra, Yoeri (graduation committee), van Horssen, Wim (graduation committee), Zitman, Tjerk (graduation committee), Delft University of Technology (degree granting institution).

Subjects/Keywords: Estuaries; Sediment transport; Idealized modelling

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Bouwman, D. (. (2019). The influence of spring-neap cycles on sediment trapping in tide-dominated estuaries. (Masters Thesis). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:83975ab7-185c-4dd2-b869-5e8fe435fdba

Chicago Manual of Style (16th Edition):

Bouwman, Dennis (author). “The influence of spring-neap cycles on sediment trapping in tide-dominated estuaries.” 2019. Masters Thesis, Delft University of Technology. Accessed October 21, 2020. http://resolver.tudelft.nl/uuid:83975ab7-185c-4dd2-b869-5e8fe435fdba.

MLA Handbook (7th Edition):

Bouwman, Dennis (author). “The influence of spring-neap cycles on sediment trapping in tide-dominated estuaries.” 2019. Web. 21 Oct 2020.

Vancouver:

Bouwman D(. The influence of spring-neap cycles on sediment trapping in tide-dominated estuaries. [Internet] [Masters thesis]. Delft University of Technology; 2019. [cited 2020 Oct 21]. Available from: http://resolver.tudelft.nl/uuid:83975ab7-185c-4dd2-b869-5e8fe435fdba.

Council of Science Editors:

Bouwman D(. The influence of spring-neap cycles on sediment trapping in tide-dominated estuaries. [Masters Thesis]. Delft University of Technology; 2019. Available from: http://resolver.tudelft.nl/uuid:83975ab7-185c-4dd2-b869-5e8fe435fdba


Delft University of Technology

3. de Goede, Roel (author). Regime shift in sediment concentrations in the Loire estuary.

Degree: 2020, Delft University of Technology

A study of five European estuaries by Winterwerp and Wang (2013) showed that tidal ranges increased significantly along with the ongoing narrowing and deepening of these estuaries. In addition to an increase in tidal range, a dramatic increase in suspended sediment concentrations has been observed in the Ems (Germany) and Loire (France) estuaries, often referred to as a regime shift towards hyperturbid state. While it is generally accepted that the increase in tidal range is a consequence of deepening and narrowing, it is not generally true that deepening and narrowing leads to a dramatic increase in sediment concentrations. Whether deepening is a potential cause for the high sediment concentrations observed in the Loire, is still unclear. Although very little observations have been reported over the 20th century, literature clearly shows that sediment concentrations increased drastically over the years. The scarcity of data not only applied for the sediment concentrations over the years but also for bathymetry and hydrodynamics, resulting in uncertainty about the historical states of the estuary. To cope with the large range of uncertainty and variability in the reported observations and model parameters, an idealised model called iFlow has been used. The strength of the iFlow model for this research was twofold. Firstly, iFlow allowed to identify the essential physical processes driving the estuarine sediment dynamics. Secondly, iFlow is computationally efficient, allowing to perform extensive sensitivity studies. In this way, we could determine which processes play a role in the current state of the Loire estuary and how they are affected by deepening. Furthermore, by mapping the effects of the uncertainty on the different physical processes, robust conclusions could be drawn about the effects of deepening despite the given uncertainty. The effects of deepening on the physical processes has been assessed by only varying the depth in the model. Deepening generally resulted in enhanced sediment import or decreased sediment export. Hence, the transport capacity in the Loire became much more favourable for the import of sediment. In order to determine the robustness of these findings, an extensive sensitivity study was performed of 14.157 simulations (1287 conditions for 11 bottom profiles over time) to capture the influence of uncertainties in multiple input parameters. For the bottom profile representing the bathymetry in the year 1900, none of the conditions resulted in a hyperturbid state, whereas independent of the conditions, the likelihood to find a hyperturbid state always increased for increasing depth. From this we can conclude, that the observed regime shift towards high sediment concentrations would not have happened without the deepening of the Loire estuary. Advisors/Committee Members: Dijkstra, Yoeri (graduation committee), Wang, Zhengbing (mentor), van Prooijen, Bram (graduation committee), Delft University of Technology (degree granting institution).

Subjects/Keywords: Loire river-estuary; Hyperturbidity; Idealized modelling; iFlow; Sediment dynamics; Sensitivity Analysis; Proces Based modelling

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

de Goede, R. (. (2020). Regime shift in sediment concentrations in the Loire estuary. (Masters Thesis). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:4d71a8e1-08e9-4663-a7b4-ae514fa59419

Chicago Manual of Style (16th Edition):

de Goede, Roel (author). “Regime shift in sediment concentrations in the Loire estuary.” 2020. Masters Thesis, Delft University of Technology. Accessed October 21, 2020. http://resolver.tudelft.nl/uuid:4d71a8e1-08e9-4663-a7b4-ae514fa59419.

MLA Handbook (7th Edition):

de Goede, Roel (author). “Regime shift in sediment concentrations in the Loire estuary.” 2020. Web. 21 Oct 2020.

Vancouver:

de Goede R(. Regime shift in sediment concentrations in the Loire estuary. [Internet] [Masters thesis]. Delft University of Technology; 2020. [cited 2020 Oct 21]. Available from: http://resolver.tudelft.nl/uuid:4d71a8e1-08e9-4663-a7b4-ae514fa59419.

Council of Science Editors:

de Goede R(. Regime shift in sediment concentrations in the Loire estuary. [Masters Thesis]. Delft University of Technology; 2020. Available from: http://resolver.tudelft.nl/uuid:4d71a8e1-08e9-4663-a7b4-ae514fa59419

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