The secrets of travelling sand
Sandy beaches and coastal regions all around the world are kept in place by adding sand: so-called sand nourishments. When applied in synergy with the natural forces of currents, waves and tides, these are nature-based solutions that help us strengthen our coastlines in the face of climate change. To design more effective and sustainable nourishments, we need knowledge on where the nourished sand actually goes and how it interacts with coastal ecosystems. Withing the NWO-funded project TRAILS (Tracking Ameland Inlet Living Lab Sediment), researchers from Wageningen University and Research, TU Delft and NIOZ tried to answer these questions.
The Ameland inlet, the entrance of the Wadden Sea between the islands of Ameland and Terschelling, was their field laboratory. For the first challenge, distinguishing nourished sand from native grains, so-called luminescence-based tracing might hold a solution. Luminescence is an inherent signal of sand grains that resets when the grain is exposed to light. In this way, each sand grain has its own unique fingerprint. This new tracing method can help to improve models that predict the pathways of the sand. Eventually, knowing where the sand ends up does not only help us to efficiently strengthen the coast, but also to predict impacts on coastal ecosystems ecosystem. Where sand ends up, it may affect the seafloor animals, which are dependent on the sediment type they live in. Vice versa, these animals can also influence sand transport themselves. Knowing more about this interaction will help us make even better predictions of sand pathways and the ecological effects of nourishments, so that we can keep both our feet dry and our ecosystems healthy in the years to come.
