Downscaling sea-level rise effects on tides and sediment dynamics in tidal bays

Abstract. Sea-level rise (SLR) not only increases the threat of coastal flooding, but also may change tidal regimes in estuaries and coastal bays. To investigate such nearshore tidal responses to SLR, a hydrodynamic model of the European Shelf is downscaled to a model of a Dutch coastal bay (the Eastern Scheldt) and forced by SLR scenarios ranging from 0 to 2 m. The results indicate that SLR induces larger increases in tidal amplitude and stronger nonlinear tidal distortion in the bay compared to the adjacent shelf sea. Under SLR, the basin shifts from a mixed flood- and ebb-dominant state to complete ebb-dominance, causing enhanced sediment export and accelerated loss of tidal flats. In this case study, we find that local impacts of SLR can be highly spatially-varying and nonlinear depending on basin geometry. Our model downscaling approach is widely applicable for establishing local SLR projections in estuaries and coastal bays.