Exploring changes in tidal dynamics in intertidal environments under sea level rise scenarios in the Wadden Sea (SE North Sea)

Recent studies in the Wadden Sea (SE North Sea) indicate a complex non-linear feedback between sea-level rise (SLR), tidal dynamics and geomorphology, posing a threat to the functioning of coastal ecosystems and the provision of ecosystem services in particular. This study focuses on the SLR-related changes in intertidal dynamics, specifically tidal inundation, tidal asymmetry, and circulation patterns. The Sylt-Rømø Bight has been selected as a case study site. The scenarios based on the projected bathymetric evolution and on mean SLR under low and high emission pathways (RCP 2.6 and RCP 8.5) were simulated using the coastal hydrodynamic model FESOM-C running on an unstructured, high-resolution mesh (up to 2 m in wetting-drying zones). Analysis reveals that only 2.2% to 3.4% (13∙10⁶ and 21∙10⁶ m²) of intertidal flat areas will be permanently submerged until 2050 under low and high emissions scenarios, respectively. On the contrary, by the end of the century, submergence increases up to 4.8% to 13.9% (29∙10⁶ and 84∙10⁶ m²). Remarkable are also the results showing that the main tidal channels experience different, even opposing, changes in mean and peak current velocities, which point to changes in transport pathways and possible changes in local erosion rates. Such spatial inhomogeneity is also depicted in shifts in the tidal asymmetry, indicating an overall transition towards a lagoon-like system as SLR accelerates. These findings underscore the importance of understanding the complex interplay of the hydrodynamic processes driving coastal dynamics and habitat change.

Primary Presenter: Gaziza Konyssova, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (gaziza.konyssova@awi.de)

Authors:

Gaziza Konyssova, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research  (Gaziza.Konyssova@awi.de)

Vera Sidorenko, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research  (Vera.Sidorenko@awi.de)

Alexey Androsov, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research  (Alexey.Androsov@awi.de)

Sara Rubinetti, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research  (Sara.Rubinetti@awi.de)

Lasse Sander, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research  (Lasse.Sander@awi.de)

Karen Wiltshire, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research  (Karen.Wiltshire@awi.de)