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Splitting up Dutch boezem systems to increase flood safety : A case study on the Friese Boezem
Rodenhuis, G.I. (2025) Splitting up Dutch boezem systems to increase flood safety : A case study on the Friese Boezem.
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| Abstract: | Climate change is increasing the flood risk in The Netherlands, because of sea level rise and heavier precipitation events. This is especially the case for the Dutch boezem systems, which are large interconnected water systems that discharge the water from the Dutch polders into a sea, lake or river. While these systems have a target water level, maintaining this water level becomes more and more difficult when the amount of water they need to discharge increases. One possible solution to keep Dutch boezem systems flood safe is to split up a boezem into two separate systems. The idea behind this intervention is that when a boezem is split, the water level in one of the new boezems can be lowered which increases the water storage capacity. In this report it was researched whether splitting up Dutch boezem systems increases flood safety, using the Friese Boezem as a case study. In order to test whether a split of the Friese Boezem improved flood safety, five alternatives for a split were simulated using a Python model. This model simulated splits of the Friese Boezem in its current scenario without sea level rise or wind effects. The results of these simulations were then compared to the results of the current situation of the Boezem without a split. After that, a sensitivity analysis was performed by conducting fixed-value tests in order to test how the models react to small changes of the parameters, and a degenerate test was performed to test whether the model gives the expected results when simulating with no in- or outflows. In the sensitivity analysis, it was also tested what happens to the models when factoring in 0.92 meters of sea level rise. Lastly, the alternatives were compared using the Analytical Hierarchy Process (AHP) to find the best option. The alternatives were compared on how much they increase flood safety and on how many other impacts they have on shipping, nature and agriculture and the built environment. In the end, all of the alternatives showed an increase in flood safety compared to the current scenario. The alternative that showed the highest increase in flood safety was an alternative where the Friese Boezem was split up into a Northern Boezem and a Southern Boezem of roughly equal size, with a new sea pump for the Northern Boezem. When modeling the Northern Boezem and the Southern Boezem in this alternative they reached a highest water level of -0.51m NAP and -1.48m NAP respectively. These are only slightly higher than their target water levels of -0.52m NAP and -1.5m NAP. The simulation of the current scenario saw a way higher peak, which reached -0.29m NAP with a target water level of -0.52m NAP. The sensitivity analysis revealed that most alternatives were not sensitive to small changes in the parameters, and all alternatives gave the expected results during the degenerate test. When modeling with sea level rise, all alternatives still performed better than the current scenario. When comparing the alternatives, the aforementioned alternative with a full split of the boezem with a new sea pump came out on top. This is because while most other alternatives had less effects on shipping, nature and the built environment, they did not increase the flood safety by as much. So, splitting up Dutch boezem systems does increase flood safety, even when factoring in sea level rise. However, this is assuming that the wind has no effect on the water levels in the boezems. |
| Item Type: | Essay (Bachelor) |
| Faculty: | ET: Engineering Technology |
| Programme: | Civil Engineering BSc (56952) |
| Link to this item: | https://purl.utwente.nl/essays/107222 |
| Export this item as: | BibTeX EndNote HTML Citation Reference Manager |
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