University of Twente Student Theses
Model validation for the evolution of intertidal areas in the Western Scheldt
Paternotte, L. (2024) Model validation for the evolution of intertidal areas in the Western Scheldt.
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| Abstract: | The Western Scheldt is an estuary located in the southwest of the Netherlands. Ecologically valuable intertidal areas are found between the channels and fringing along the shore. These areas can be divided into flats (Dutch: platen) and marshes (Dutch: schorren). Sea level rise threatens the intertidal regions, as the size of this area might decrease with increasing water levels. The research institute Deltares developed a Delft3D (process-based, numerical) model to forecast the morphological evolution of the Western Scheldt with global sea level rise of up to 2.63 m from 2020-2100. However, the model’s skill to predict the development of the intertidal region was uncertain. To study this, hindcasts were done from 1964-2012 using the same model. In this study, the hindcast results are compared to bathymetric data from measurements by Rijkswaterstaat. This report presents an analysis of the differences between the model results and measurement data. The development of the intertidal areas is compared on two spatial scales. First for the total area spanning from the mouth near Vlissingen to the east near Bath, and secondly for the same area split up into western, middle and eastern parts. Measured water level data in the estuary for 1965-2010 is considered to determine the intertidal range. Bed levels are studied from approximately mean low water during spring tide to mean high water during spring tide. Since the difference between low and high water, the tidal range, increases eastward and varies over time, the bed level boundaries of the intertidal zone vary in the analyses. The results show that the model underestimates the total intertidal area both with and without including wave modelling. Besides that, the average height of the intertidal area is also underestimated, except for 2010. In both cases, the hindcast results with waves are generally closer to the bathymetric data than without waves. On average, the no-wave hindcast underestimates the total intertidal area with 8.6 million m2 , which is 12%. This hindcast underestimates the average bed level height with 15.1 cm on average. For the wave hindcast, this is 7.0 million m2 (10%) for the total intertidal area, and 12.9 cm for the average bed level height. In contrast, the shapes of hypsometric curves of the intertidal area based on the hindcast without waves are more similar to the measurements than those based on the wave hindcast. On a smaller spatial scale, changes to the intertidal area over time are more pronounced in the model results than in the measured data. Since the model results show comparable trends in the development of the Western Scheldt’s intertidal region as the measured data for 1965-2010, the Delft3D model seems applicable for predicting the evolution of intertidal areas. However, model assumptions, particularly for dredging and dumping activities, limit the accuracy of the hindcasts. |
| Item Type: | Essay (Bachelor) |
| Faculty: | ET: Engineering Technology |
| Programme: | Civil Engineering BSc (56952) |
| Link to this item: | https://purl.utwente.nl/essays/104482 |
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