Samenvatting

In the following thesis, research is conducted on the effect of sea-level rise and expected hydraulic load levels for the Scheldt Estuary, currently and in the future. As climate changes advances and the sea-level rises, insight into the effects of the rise on our coastal area's is essential. Rijkswaterstaat wants an overview of the expected impacts for their involvement in the research program "zeespiegelstijging" using the new WBI2017 instruments. Now, this information is lacking and have asked several students to research it, with this thesis focusing on the Scheldt Estuary. The goal is to find and visualise the extent of the impact on dykes along the estuary using WBI2017 software, as well as providing insight into the impact that changing the wind statistics station from Vlissingen to Cadzand. The goal is divided into several sub-questions to answer its central question accurately. The first to aim to find out what the hydraulic load levels are being experiences in 2023, 2050 and 2100, relating the answer to the required crest heights for the w+ scenario. Third and fourth questions aim to determine which sections experience the most substantial loading and how significant the differences between sight years are for these locations. Lastly, a look was taken into the alternative wind data, and how significant the difference is between the two for the three years.
Answering these questions was done by a quantitative software analysis using Hydra-NL and statistical analyses on the calculation results. Each dyke segment was calculated on the water levels and hydraulic load levels for 2023, 2050 and 2100. These calculations resulted in a large quantity of information, which was then summarized using excels pivot tables. From the pivot table, several different graphs and tables were created all presented in chapter 5. Results and the data were also used as input for the GIS maps. The maps are situated at the end of results sub-section highlight the segments on the representing side and indicating the varying hydraulic loads and the explanation of it. The chapter sections summarise the results of the calculations, which are then related to each other in the representing maps per segment.
The results compared to the current dyke heights resulted in transgression percentages of at the lowest 3% in the south side of the Eastern Scheldt. At the highest 78% in the south of the Western Scheldt. With required dyke heights ranging from 4 meters to 14 at the most, depending on their location and orientation compared to the contributing wind direction. Then specific to the Western Scheldt, the different wind statistics show an average difference ranging from 4 cm to 70 cm, though the difference ranges further of -10 cm up to 1.2 meters. Even though a select few locations on the northern side show a decrease when using Cadzands data, the majority shows an increase in calculated hydraulic load levels.
The results presented show a global overview of the expected hydraulic load levels for a worst-case scenario in the W+ OI scenarios. However, there are a few discussion points mainly focussed on the Eastern Scheldt where several locations were missing in the calculations, and the results were therefore generalised per section. Also, the available profiles are somewhat out-dated as indicated by the waterboard the data lack the latest adjustments to the dykes as the last measurement was in 2010. Moreover, the results are challenging to validate as the used software is new, and these students performed assessments are the first indications. These points, the conclusions and recommendations formed from them are discussed at length in the final three chapters of the thesis.