Short description and objective of the project:
With increasing sea level rise, increasing volumes of sand are required to nourish the Dutch coast. To satisfy this demand, increasing volumes of sediment are extracted from the Netherlands Continental Shelf (NCS). To ensure future availability of sediment, make efficient use of limited space on the NCS and reduce sailing costs, the policy has now changed to allow for deep sand extraction with a pit depth exceeding two meters. However, the impact these deep extraction pits have on their environment may be severe.
Firstly, the extraction pits directly change the local topography and the local flow characteristics. Secondly, these extraction pits may disturb already present bedforms; in this study, we specifically focus on sand waves: wave-shaped bedforms with a wavelength of hundreds of meters, height of several meters and migration rate of multiple meters per year. Thirdly, the low flow velocities in the promote settling of fine (possibly cohesive) sediment, changing the sediment composition in the pit.
All these effects combined have a large impact on the seabed, and with that on the suitability for various organisms that live in and around extraction pits. These so-called benthic organisms are known to be sensitive to the sediment composition, but also to flow-induced shear and local topography.
In this thesis, we therefore aim to investigate the interaction between sand wave dynamics, sediment composition and benthic organisms. Although there is still some freedom in the exact shaping and formulation of this assignment, possible research questions could address:
- Exploring how benthic organisms change sand wave evolution
- How the sand wave topography and sediment composition change suitability for benthic organisms
Currently, a model is available to model the temporal evolution of sand waves and cohesive sediment. We foresee that this thesis extends the model to also include the evolution of benthic organisms.
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