Sand Trapping Fences as a Nature-Based Solution for Coastal Protection: An International Review with a Focus on Installations in Germany

Abstract

Sand trapping fences are a widely used nature-based solution to initiate dune toe growth along sandy shorelines for coastal protection. At present, the construction of sand trapping fences is based on empirical knowledge, since only a few scientific studies investigating their efficiency exist. However, the restoration and maintenance of beach-dune systems along the coast requires knowledge of the interaction between the beach-dune system and the sand trapping fences to provide guidance for coastal managers on how and where to install the fences. First, this review gives an overview of the typical aerodynamic and morphodynamic conditions around a single porous fence and the influence of various fence height and porosity values to understand the physical processes during dune establishment. Second, different approaches for evaluating the efficiency of sand trapping fences to trap sediment are described. This review then highlights significant differences between sand trapping fence configurations, nationally as well as internationally, regarding the arrangement, the materials used, and the height and porosity. In summary, it is crucial to enable an intensive exchange among the respective coastal authorities in order to create uniform or transferable guidelines taking local conditions into account, and thus work collaboratively on the idea of sand trapping fences as a nature-based solution in coastal areas worldwide.