MODELLING THE EFFECT OF SALT MARSHES FOR COASTAL PROTECTION

Salt marshes are populated in the East Frisian Wadden Sea behind the barrier islands and in the foreland areas, functioning as a coastal protection measure and carbon sink, and enhancing biodiversity and ecology. Increased understanding of the interactions of salt marshes with hydro-morpho-dynamics supports to use them as a nature-based-solution (NBS) for the coastal protection. The main objective of this study within the framework of the EU REST-COAST project is to quantify the role of salt marshes in wave attenuation and mitigation of coastal erosion for different present and future scenarios, and to increase awareness of policy/coastal managers using salt marsh as a potential NBS for coastal protection. This investigation is being carried out using the exemplary salt marsh community in Ley Bay, which has dimensions of about 5 km × 5 km, and is located in the tidal basin behind Borkum and Juist barrier islands, adjacent to the Ems-Dollard estuary. The salt marsh community covers about 1⁄3 of the bay area lying around +2 m NN attached to the foreland dyke (Fig. 1b and c: green-polygon). The study area is characterised by semi-diurnal meso-tides (mean tidal range ~2.5 m) and high waves (Hs) from the N-W sector reaching up to about 6 m (at 20 m depth) (Herman et al., 2009).