Deltares scale model testing for stability & wave attenuation
Delta Flume
Due to their low-lying nature, coral atoll islands are widely acknowledged to be amongst the most vulnerable environments to climate change. Most of them are predicted to be uninhabitable by the mid-21st century because of sea-level rise. However, these forecasts are based on relatively simple hydrodynamic models that consider the islands immobile, whereas, when overwashed during storms, the islands can vertically accrete due to sediment deposition. Repeated overwash can enable atoll islands to keep up with rising sea level.
This potentially provides opportunities for island communities to prolong habitability through innovative adaptation strategies, instead of having to construct expensive coastal defences or traumatically relocate to regions with no flood risk.
Wave attenuation testing in Delta Flume
Protecting coastal areas and islands against rising sea levels and the forces of waves requires big equipment and major work. As part of the Artificial Reefs Program from Boskalis we are exploring various possibilities to deploy artificial reefs as a coastal protection mechanism. The reasoning is relatively simple. Because when a coastal reef manages to break waves – thereby reducing their force – less erosion occurs on the coast, potentially also reducing the amount of rock needed to protect the vulnerable coast.
With 11 modular 1:3 scale model reefs from ReefSystems, TU Delft and the University of Plymouth. are currently testing how this Building with Nature solution for coastal protection could contribute to these problems with the aim of putting this solution into practice on a much larger scale.
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Scheldt Flume
Deltares is an independent institute for applied research in the field of water and subsurface. In 2021 ReefSystems has been selected by a jury from Deltares as best contender for two weeks of testing time at one of their facilities. In the Scheldt Flume 3 x 42 MOSES modules (1/20 scale) were placed on baseplates with different weights. Hydraulic Engineering MSc student Carolien Diederen from TU Delft and Menno de Ridder from Deltares have set up a detailed testing plan. Various storm conditions were simulated at different depths to find out when the reefs will start to move. Guided by Marcel van Gent (Deltares), Jeroen van den Bos (Boskalis), Barend van den Bosch (Van Oord) and Mark Voorendt (TU Delft), a useful tool will be developed to determine the minimum necessary weights of our reefs in different conditions. Learning about the effects of different hydraulic conditions on the stability of our reefs will enable us to install reefs to stimulate biodiversity on a bigger scale. For instance as scour protection in offshore wind farms or nearer to shore to prevent coastal erosion.