Public thesis defense Ny Riana Randresihaja - ELIE
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Modelling storm surges in the Scheldt-North Sea continuum under present and future climate conditions
Wednesday November 18th, 2026 - 4:15pm - Ocean Room, de Serres building (B002) - Place Croix du Sud, 2 - 1348 Louvain-la-Neuve
Estuaries are a key component of coastal systems, influencing hydrodynamics, ecosystem functioning and local socio-economic activities. At the interface between the Scheldt River and the North Sea, the Scheldt estuary forms a strongly convergent channel bordered by intertidal flats and marshes, with the port of Antwerp at its head. The estuary has been extensively modelled for its morphological evolution, dredging strategies and flood management, but storm surges have received less attention, and the estuary and the adjacent sea have rarely been resolved within a single domain. In this thesis, we use the 2D version of the multiscale hydrodynamic model SLIM to study how storm surges propagate and amplify along the Scheldt–North Sea continuum. We first build and validate a configuration that resolves the continuum on a single mesh, from the tidal channels of the upper estuary to the open shelf, over five continuous years. We then assess, for Storm Xaver (2013), how the resolution of the atmospheric forcing affects the simulated estuarine surge, and find that spatial resolution matters more than temporal resolution in this case. Finally, we simulate a panel of plausible future storms under a high-emission scenario up to the end of the 21st century. The panel shows no robust intensification of the meteorological surge over the century, and surge severity varies more with position along the continuum than with storm track, extreme flood levels increasing several-fold from the open sea to the head of the estuary. In this panel, positive and negative surges behave as distinct hazards: the rarest flood levels approach an upper limit, whereas the rarest low waters keep deepening, and Antwerp ranks among the most exposed gauges for both. This thesis provides a single-domain representation of the Scheldt–North Sea continuum and underlines the need to consider both signs of the surge when assessing estuarine hazard.
Jury members
Prof Emmanuel HANERT (UCLouvain), Supervisor
Prof. Marilaure GRÉGOIRE (ULiège), Supervisor
Prof. Marnik VANCLOOSTER (UCLouvain), Chairperson
Dr. Jonathan LAMBRECHTS (UCLouvain), Secretary
Dr. Olivier GOURGUE (Royal Belgian Institute of Natural Sciences)
Prof. Xavier FETTWEIS (ULiège)
Prof. Emil STANEV (Helmholtz-Zentrum Hereon)