Rising sea levels are increasingly bringing nature-based solutions to the fore. The construction of dunes in front of the dike are an example of such a nature-based solution. These protect us from flooding, but also provide other ecosystem services such as a pleasant environment for recreation, increased biodiversity, reduced sand nuisance behind the dunes, etc.
However, these solutions themselves require a lot of sand, while sand resources in the North Sea are rapidly depleting. Moreover, sand extraction also has an impact on the marine ecosystem. The SUSANA project (Sustainable Use of SAnd in NAture-based solutions) will develop a coupled ecosystem services model to weigh up the pros and cons of a dune in front of the dike (dune-by-dike). This model will support the development of a long-term strategy for the sustainable use of sand in nature-based solutions. The project focuses on two aspects of sustainability: (1) the (re)use of lower-quality sandy material and (2) striving to reduce the impacts of sand extraction.
The specific research questions are:
- To what extent can alternative sand sources also provide the necessary ecosystem functions and services in a dune-by-dike?
- What is the impact of different sand extraction regimes on the ecosystem functions and services of the bottom ecosystem on the different sandbanks, and on the more distant valuable gravel beds?
Based on these research questions, a linked ecosystem services model will be developed, which will allow us to weigh up the advantages and disadvantages of constructing a dune-by-dike, and the sand extraction required to do so, respectively.
The fieldwork has already started. This video (RBINS/Vera Van Lancker) illustrates the work on board the RV Simon Stevin (VLIZ) during a campaign at sea in early March 2023: taking vibrocores where sediment samples were extracted from the bottom via drilling to a depth of 2.5m. For RBINS, the aim was to map dredge dumping areas as an alternative source area of sand. Dumping leaves mainly sandy material at the site as the fine material is washed out by currents. The study sites were mainly situated in the coastal zone. However, sand quality here is considerably lower than in the more seaward reclamation areas, but possibly sufficient for the construction of nature-based coastal protection such as dune-by-dike. At night, the seabed and upper subsurface layers were mapped using acoustic measurement techniques.
The SUSANA project started in February 2023, lasts for 3 years and is financially supported by VLAIO/The Blue Cluster.
The project team consists of the following partners: Universiteit Antwerpen (coordinator), Universiteit Gent, Katholieke Universiteit Leuven, ILVO (Research Institute for Agriculture, Fisheries and Food) and RBINS (Royal Belgian Institute of Natural Sciences).