|Validation of North Sea models: sub report 2. The impact of sea level rise on hydrodynamics: North Sea and Scheldt estuary|
Chu, K.; Vanlede, J.; Smolders, S.; Decrop, B.; Mostaert, F. (2020). Validation of North Sea models: sub report 2. The impact of sea level rise on hydrodynamics: North Sea and Scheldt estuary. Version 3.0. FHR reports, 19_058_2. Flanders Hydraulics Research/IMDC: Antwerp. VII, 37 + 2 p. app. pp.
Hydraulics and sediment > Hydrodynamics > Tides
Physics > Mechanics > Fluid mechanics > Hydrodynamics
ANE, Noordzee [Marine Regions]; ANE, Schelde-estuarium [Marine Regions]
|Project|| Top | Auteurs |
- AvdTII - Validatie van Noordzee modellen en effecten SLR
: Vlaamse overheid; Beleidsdomein Mobiliteit en Openbare Werken; Vlaams Ministerie van Mobiliteit en Openbare Werken; Departement Mobiliteit en Openbare Werken; Afdeling Maritieme Toegang, meer
The influence of Sea Level Rise (SLR) on the tidal characteristics in the North Sea and in the Scheldt estuary is evaluated in a scenario analysis for three scenarios of SLR: 1 m, 2 m and 3 m respectively. DCSMv6-ZUNOv4 and SCALDIS are selected as the modelling instruments. The models are run for 2 spring-neap cycles in 2015 without wind and pressure forcing (purely harmonic run).
In the North Sea, the M2 tidal amplitude increases in the Southern Bight under SLR. Along the Belgian coast, the M2 amplitude increases with 2 cm, 4 cm and 6 cm with SLR of 1 m, 2 m and 3 m. The M2 tidal phase decreases, consistent with the faster propagation of the tidal wave in deeper water. The southern amphidromic point (closest to the Belgian Coastal Zone - BCZ) is expected to move north-eastwards with SLR of 1 and 2m. In the scenario of SLR of 3m, the amphidromic point shifts to the north-west.
In the Scheldt Estuary, the changes on high water level are generally in proportion to the SLR of 1m, 2m and 3m. However the high water level drops in the Upper Sea Scheldt, mainly because the overflowing dikes of the Flood Control Areas (FCA’s) are represented in the model mesh, and the depoldered areas become drowned with SLR. Note that this corresponds to an initial response without autonomous development. In reality, SLR will not occur overnight, and the estuarine morphology will change on a longer timescale. The redistribution of sediments (erosion/deposition) will modify the hydrodynamics in the estuary, which in turn will change the morphology in a feed-back loop that is difficult to model accurately.
The tidal asymmetry along the thalweg is evaluated based on tidal duration (falling/rising, ebb/flood) and velocities (maximum and mean) under different SLR scenarios. With SLR the initial effect in the estuary is that it becomes less ebb-dominant in terms of duration asymmetry upstream of km 100 (more equal timing of periods of ebb and flood). But the estuary becomes more ebb-dominant in terms of velocity asymmetry. The different results for different definitions of tidal asymmetry does not allow a straightforward interpretation in terms of expected morphological response, and warrants future research, e.g. with a sediment transport model.