Tidally Induced Transport Dynamics in a Wadden Sea Tidal Basin and Its Changes Under Future Sea Level Rise Scenarios
Coastal systems in the Wadden Sea are shaped by the interplay between tidal dynamics, basin geomorphology, and atmospheric forcing. These interactions create spatial structures of hydrodynamic connectivity that govern transport processes, ecological functioning, and the interpretation of long-term observations. However, the persistence of these structures under future sea level rise and changing wind conditions remains uncertain.
This dissertation investigates the organisation of tidally induced transport in the Sylt-Rømø Bight, a semi-enclosed tidal basin in the northern Wadden Sea, and its response to future climate forcing. Using high-resolution hydrodynamic modelling with FESOM-C, Lagrangian particle tracking, network-based connectivity analysis, and long-term environmental observations, the study establishes a mechanistic link between physical transport structure, ecological variability, and climate change.
The results show that the basin is organised into distinct hydrodynamic regions with characteristic residence times and exchange pathways. Under sea-level rise, this spatial organisation remains largely intact, but transport efficiency decreases. Reduced tidal asymmetry leads to weaker net transport, longer residence times, and a shift toward more internally retentive, lagoon-like behaviour, despite an increasing tidal prism.
Wind forcing acts primarily as a short-term modifier of transport processes. Summer winds enhance dispersion without altering dominant pathways, while stronger winter winds increase resuspension and short-term variability but do not reorganise basin-scale transport.
Analysis of long-term monitoring data demonstrates that observational stations reflect their local connectivity context. A shallow station responds rapidly to local forcing, whereas a deeper station integrates signals over larger spatial and temporal scales. Suspended matter variability is controlled mainly by physical forcing in winter, while biological processes increasingly dominate toward spring and summer.
Methodologically, the thesis provides a multi-scale framework for analysing connectivity in tidal basins. This approach is transferable to other coastal systems and supports improved monitoring strategies under changing environmental conditions.
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