University of Twente Student Theses
Assessing alternative discharge distributions at the Pannerdensche Kop and IJsselkop to address climate change impacts on the Dutch Rhine system by 2100
Schoonderwoerd, L.M. (2025) Assessing alternative discharge distributions at the Pannerdensche Kop and IJsselkop to address climate change impacts on the Dutch Rhine system by 2100.
|
PDF
6MB |
| Abstract: | The Dutch Rhine branches are among the most heavily engineered river systems in the world. Groynes, weirs, control structures, and flood channels are built to manage the flow and thereby support river functions such as conveyance, water supply, habitat, and transportation. In addition, the river system is affected by climate change. This is evident trough a change in the hydrograph. Extreme discharge events will be more extreme and occur more often. It is therefore questioned how the discharge, both low and high flows, should be distributed over the three distributaries Waal, Nederrijn-Lek and IJssel. This study concluded on performance indicators to include in the evaluation of the river functions. The conveyance capacity is quantified on the water level rise along the length of the river branch from the current design discharge to future design discharge. The fresh water supply of the river has been quantified on the low flows, the low flow durations, and the return periods. The contribution of the river to habitat has been investigated based on both the water depth dynamics in the floodplain, and the area of the floodplain. Lastly, the transportation of the river has been evaluated based on the number of days per year that the minimum water depths are exceeded. Thereafter, this study evaluated the impacts of climate change using the 1D hydrodynamical model SOBEK and a Multi Criteria Analysis. The results have shown that based on the KNMI climate scenarios, the river functionalities will depreciate except from habitat. Moreover, the scenarios showing a trend toward a drier future climate exhibit a larger negative impact on the river functions than the scenarios showing a trend toward a wetter future climate. Overall, the river functions are most vulnerable to a drier future climate in combination with high emissions. The design discharge at Lobith is expected to increase from 16,000 m3 /s to 18,000 m3 /s in the year 2100. The current discharge distribution holds 2/3 towards the Waal, 2/9 toward the Nederrijn-Lek and 1/9 towards the IJssel. Based on literature and expert judgement, two alternative discharge distributions have been proposed where for both the Nederrijn-Lek is spared. The Nederrijn-Lek has relative narrow floodplains, is surrounded by ribbon development, and an increase in water levels along the Nederrijn-Lek will pose the larger flood risks than the Waal and IJssel. One scenario entails allocating 80% of the extra discharge to the Waal and 20% to the IJssel (80-20). The second scenario include a distribution of 60% to the Waal and 40% to the IJssel (60-40). The model results showed that in the context of a drier future climate and high emissions an alteration in the discharge distribution is advantageous. Also, the distribution 60-40 is optimal as this is better for the conveyance, habitat, and transport. A modification to the discharge distribution ratio from the current to 60-40 will result in an increase of discharge toward the Waal and IJssel. For this, three types of river widening measures have been proposed along the IJssel to account for the additional discharge. Including a dike relocation, the excavation of the floodplains and the lowering of the main channel have been investigated. Additionally, the model results showed that a dike relocation and excavation of the floodplain do have a favourable impact on the river functions in the drier climate scenario based on high emissions. Contrary, excavating the main channel will have negative effects on the functions: habitat and transportation. In conclusion, it is important to further investigate the technical feasibility of altering the discharge distribution for the additional 2,000 m3 /s design discharge and investigate the impacts outside of the scope of this study. Lastly, it is advised to critically reserve space for the river and investigate whether smaller interventions can yield the same effect on the river functions as either of two large scale river widening interventions. |
| Item Type: | Essay (Master) |
| Faculty: | ET: Engineering Technology |
| Subject: | 56 civil engineering |
| Programme: | Civil Engineering and Management MSc (60026) |
| Link to this item: | https://purl.utwente.nl/essays/106016 |
| Export this item as: | BibTeX EndNote HTML Citation Reference Manager |
Show download statistics for this publication
Show download statistics for this publicationRepository Staff Only: item control page