Heatwave analysis of modelled thermal response of intertidal sediments in the Dutch Wadden Sea

This thesis investigates how water-column heatwaves translate into sediment heatwaves in the Dutch Wadden Sea, and how this propagation changes with sediment depth and inundation level. A mechanistic sediment temperature model, TempSED, was applied to analyse the vertical propagation into deep sediment along an inundation gradient from -0.5 to 0.5m NAP. The results show that water-column heatwaves clearly propagated into the sediment, but that their expression changed strongly with depth and bed elevation. Near the surface, sediment heatwaves were more intense and showed stronger short-term variability, especially at less frequently inundated sites. These higher sites experienced stronger absolute temperature peaks, likely because exposed sediment is more directly heated by solar radiation and air temperature during low tide. With increasing depth, heatwave intensity decreased, but events became more persistent. This indicates that sediment heatwaves are not only short surface events, but can develop into longer-lasting subsurface thermal anomalies. In recent warm years, the model suggested the formation of a persistent deep warm anomaly that did not fully dissipate between seasons. This raises the possibility that repeated warm summers and mild winters could reduce the ability of deeper sediment layers to restore to their climatological mean.If you have any questions. Reach out to me at [e-mail]