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dc.rights.licenseCC-BY-NC-ND
dc.contributor.advisorMaas, L.R.M.
dc.contributor.advisorSwart, H.E. de
dc.contributor.authorVijsel, R.C. van de
dc.date.accessioned2015-08-05T17:01:05Z
dc.date.available2015-08-05T17:01:05Z
dc.date.issued2015
dc.identifier.urihttps://studenttheses.uu.nl/handle/20.500.12932/20803
dc.description.abstractA model for subtidal estuarine salt and flow dynamics in a 2DV (along-channel and vertical) domain is developed, describing the evolution of variables averaged over the estuarine basin. These variables are domain-averaged horizontal and vertical salinity gradient and domain-averaged angular momentum in the 2DV-plane. The latter measures estuarine circulation strength. The model is defined under the assumptions that the lowest-order, in this case spatially linear, salt- and flow-field contributes dominantly to domain-integrals. Domain length is here dynamically related to horizontal salt gradient and defined as the furthest up-estuarine salt intrusion. The methods applied in the current study reduce the governing equations (partial differential equations) to coupled ordinary differential equations (ODE's), i.e. evolution equations for the three basin-averaged variables. A major advantage is that (steady) solutions to ODE's are more easily found and can be readily analysed. All individual terms contributing to the evolution equations have a clear physical meaning. The influence of all terms on the model's analytical and numerical steady state solutions could be interpreted. Yet the complexity of the resulting evolution equations and solutions limits complete physical understanding and comparison to other (modelling) studies. At least one steady state solution is associated with the typical estuarine stratification and circulation and is linearly stable. The estuary evolves into this state when perturbed from a homogeneous rest state by imposing a weak horizontal salinity gradient and angular momentum and a strong vertical stratification. The behaviour of this steady state as a function of depth and river discharge, for the parameter settings of a partially mixed estuary, is qualitatively comparable to other model studies. The vertical stratification is however unrealistically strong, most likely due to the formulated seaward boundary conditions. Suggestions are given to improve the seaward boundary conditions and to reduce the complexity of the model, to further improve understanding of its solutions. With some adaptations, the constructed model has the potential to gain more insight into basin-averaged subtidal estuarine processes and to study its time-evolution.
dc.description.sponsorshipUtrecht University
dc.format.extent3386253
dc.format.mimetypeapplication/pdf
dc.language.isoen
dc.titleEstuarine subtidal flow and salinity dynamics - Modelling the evolution of basin-averaged variables
dc.type.contentMaster Thesis
dc.rights.accessrightsOpen Access
dc.subject.keywordssubtidal estuarine dynamics; estuarine circulation and stratification; basin-avaraged modelling; low-order moments; evolution equations; multiple equilibria
dc.subject.courseuuMeteorology, Physical Oceanography and Climate


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