TY - JOUR

T1 - Projected Responses of Tidal Dynamics in the North Sea to Sea-Level Rise and Morphological Changes in the Wadden Sea

AU - Jordan, Christian

AU - Visscher, Jan

AU - Schlurmann, Torsten

N1 - Funding Information: We gratefully acknowledge the provision of bathymetric data by EMODnet (EMODnet Bathymetry Consortium, 2018), the Rijkswaaterstaat (Wiegmann et al., 2005), the BAW (Sievers et al., 2020a), the WSV (WSV, 2020), and the Kystdirektoratet. We would also like to thank the British Oceanographic Data Centre (BODC), the Service Hydrographique et Océanographique de la Marine (SHOM), the Rijkswaterstaat, the WSV, the Bundesanstalt für Gewässerkunde (BfG), the Danish Kystdirektoratet, and the Norwegian Katverket for providing tidal gauge data. Meteorological data used in this study were obtained from the Hans-Ertel Centre for Weather Research and the Deutscher Wetterdienst (DWD) (Bollmeyer et al., 2015). Sediment data by Wilson et al. (2018) were complemented by data from the BAW (Sievers et al., 2020b), the Rijkswaterstaat (Rijkswaterstaat, 1998), and the Helmholtz-Zentrum Geesthacht (HZG) (Bockelmann, 2017). Coastlines, which are shown in this study, were adapted based on shapefiles by OpenStreetMap (2019). The Matlab toolbox by Rochford (2020) was used to produce the Taylor diagram. Perpetually uniform color maps were used in this study to prevent visual distortion of the data (Crameri, 2018a,b). Special thanks go to Mathias Wien and Marieke Winter for conducting preliminary model simulations.

PY - 2021/6/21

Y1 - 2021/6/21

N2 - This study explores the projected responses of tidal dynamics in the North Sea induced by the interplay between plausible projections of sea-level rise (SLR) and morphological changes in the Wadden Sea. This is done in order to gain insight into the casual relationships between physical drivers and hydro-morphodynamic processes. To achieve this goal, a hydronumerical model of the northwest European shelf seas (NWES) was set-up and validated. By implementing a plausible set of projections for global SLR (SLRRCP8.5 of 0.8 m and SLRhigh−end of 2.0 m) by the end of this century and beyond, the model was run to assess the responses of the regional tidal dynamics. In addition, for each considered SLR, various projections for cumulative rates of vertical accretion were applied to the intertidal flats in the Wadden Sea (ranging from 0 to 100% of projected SLR). Independent of the rate of vertical accretion, the spatial pattern of M2 amplitude changes remains relatively stable throughout most of the model domain for a SLR of 0.8 m. However, the model shows a substantial sensitivity toward the different rates of vertical accretion along the coasts of the Wadden Sea, but also in remote regions like the Skagerrak. If no vertical accretion is assumed in the intertidal flats of the Wadden Sea, the German Bight and the Danish west coast are subject to decreases in M2 amplitudes. In contrast, those regions experience increases in M2 amplitudes if the local intertidal flats are able to keep up with the projected SLR of 0.8 m. Between the different scenarios, the North Frisian Wadden Sea shows the largest differences in M2 amplitudes, locally varying by up to 14 cm. For a SLR of 2.0 m, the M2 amplitude changes are even more amplified. Again, the differences between the various rates of vertical accretion are largest in the North Frisian Wadden Sea (> 20 cm). The local distortion of the tidal wave is also significantly different between the scenarios. In the case of no vertical accretion, tidal asymmetry in the German estuaries increases, leading to a potentially enhanced sediment import. The presented results have strong implications for local coastal protection strategies and navigation in adjacent estuaries.

AB - This study explores the projected responses of tidal dynamics in the North Sea induced by the interplay between plausible projections of sea-level rise (SLR) and morphological changes in the Wadden Sea. This is done in order to gain insight into the casual relationships between physical drivers and hydro-morphodynamic processes. To achieve this goal, a hydronumerical model of the northwest European shelf seas (NWES) was set-up and validated. By implementing a plausible set of projections for global SLR (SLRRCP8.5 of 0.8 m and SLRhigh−end of 2.0 m) by the end of this century and beyond, the model was run to assess the responses of the regional tidal dynamics. In addition, for each considered SLR, various projections for cumulative rates of vertical accretion were applied to the intertidal flats in the Wadden Sea (ranging from 0 to 100% of projected SLR). Independent of the rate of vertical accretion, the spatial pattern of M2 amplitude changes remains relatively stable throughout most of the model domain for a SLR of 0.8 m. However, the model shows a substantial sensitivity toward the different rates of vertical accretion along the coasts of the Wadden Sea, but also in remote regions like the Skagerrak. If no vertical accretion is assumed in the intertidal flats of the Wadden Sea, the German Bight and the Danish west coast are subject to decreases in M2 amplitudes. In contrast, those regions experience increases in M2 amplitudes if the local intertidal flats are able to keep up with the projected SLR of 0.8 m. Between the different scenarios, the North Frisian Wadden Sea shows the largest differences in M2 amplitudes, locally varying by up to 14 cm. For a SLR of 2.0 m, the M2 amplitude changes are even more amplified. Again, the differences between the various rates of vertical accretion are largest in the North Frisian Wadden Sea (> 20 cm). The local distortion of the tidal wave is also significantly different between the scenarios. In the case of no vertical accretion, tidal asymmetry in the German estuaries increases, leading to a potentially enhanced sediment import. The presented results have strong implications for local coastal protection strategies and navigation in adjacent estuaries.

KW - climate change

KW - hydrodynamic model

KW - morphological changes

KW - North Sea

KW - sea-level rise

KW - tidal dynamics

KW - Wadden Sea

UR - http://www.scopus.com/inward/record.url?scp=85109083841&partnerID=8YFLogxK

U2 - 10.3389/fmars.2021.685758

DO - 10.3389/fmars.2021.685758

M3 - Article

AN - SCOPUS:85109083841

VL - 8

JO - Frontiers in Marine Science

JF - Frontiers in Marine Science

SN - 2296-7745

M1 - 685758

ER -