For years, sand nourishment has been an important way to protect the Dutch coast against erosion and rising sea levels. But we know surprisingly little about one type of nourishment, shoreface nourishment. A recent scientific review article by the University of Twente maps out existing knowledge in this area and underlines the need for further research.
In shoreface nourishments, sand, dredged from the offshore seabed, is placed just before the coast. This is done to support natural processes and strengthen the coastline sustainably. Shoreface nourishments are crucial to keep the coast safe and attractive, in light of sea level rise and socio-economic developments. However, it appears that much is still unknown about this way of coastal maintenance.
The article, based on tens of field studies, laboratory experiments and computer models, identifies four important knowledge gaps:
1. Uncertainty about sediment transport pathways: It is not yet well known how the nourished sand moves over the seabed and along the coast.
2. Design choices: The influence of the location, size and grain size of the sand on the effectiveness of nourishment has not been sufficiently investigated.
3. Long-term cumulative effects: What is the impact of repeated nourishments on the large scale (tens of kilometres, decades)?
4. Limitations in calculation models: Existing models fall short in reliably predicting the effect of shoreface nourishments.
The international group of authors led by UT researcher (Faculty of ET) Jebbe van der Werf argues for a targeted research agenda that should lead to more in-depth and practically applicable knowledge. Only in this way can nourishment continue to be an effective means of protecting the coast in the future and at the same time keeping it attractive for people and nature. The SOURCE research project is currently working hard to increase knowledge of sand replenishment.
Publication: Eart-Science Review paper Shoreface nourishments: Research advances and future perspectives by Jebbe van der Werf et al.
