The sediment exchange between the Dutch Wadden Sea and the North Sea coastal zone is of key importance to Dutch coastal management. By managing our coastal sediment more effectively, we will set the stage for a more sustainable future, in spite of the challenges that lie ahead. This dissertation also points forward to numerous opportunities for further investigation, including the continued development of the connectivity framework and SedTRAILS. We foresee that the main impacts of this project will be to improve nourishment strategies, numerical modelling, and field data analysis. The techniques developed here are useful in a wider range of coastal settings beyond Ameland, and are already being applied in practice. We also established a quantitative approach for looking at and thinking about sediment pathways via the sediment connectivity framework, and developed a Lagrangian model to visualize and predict these pathways efficiently. These include a method for analyzing the stratigraphy and mapping the morphodynamic evolution of ebb-tidal deltas, a new metric for characterizing suspended sediment composition, and innovative use of sediment tracers.

Before we could begin to tackle this challenge, we needed to develop new tools and techniques for analyzing a combination of field measurements and numerical models. To reach this goal, we focused our analyses on Ameland ebb-tidal delta in the Netherlands. The main goal of this project was to describe and quantify the pathways that sediment takes on an ebb-tidal delta. However, insufficient knowledge of sediment transport pathways at tidal inlets and ebb-tidal deltas prevents an informed response in these areas. Strategic sand nourishments could mitigate the threat of coastal erosion and sea level rise on barrier island coasts while limiting ecological impacts. In an era of rising seas and other challenges posed by climate change, coastal regions like the Netherlands are facing ever graver threats. According to the low-end scenario, there will be hardly any effect due to SLR until 2100, whereas according to the high-end scenario the effect will be noticeable already in 2050. Over the long term, by the year 2100, the effect depends on the SLR scenarios. These maximum rates are compared to the combined scenarios of SLR and extraction-induced subsidence, in order to explore the future state of the Dutch Wadden Sea.įor the near future, up to 2030, the effect of accelerated SLR will be limited and hardly noticeable. These models are used to evaluate the maximum rates of sediment import into the tidal basins in the Dutch Wadden Sea. The height of the tidal flats is the result of the balance between sand supply by the tide and resuspension by waves.Īt present, long-term modelling for evaluating the effects of accelerated SLR mainly relies on aggregated models. The interaction between tidal channels and tidal flats is governed by both tides and waves. In the Dutch Wadden Sea, residual flow, tidal asymmetry and dispersion are dominant. The residual sediment transport between a tidal basin and its ebb-tidal delta through the tidal inlet is influenced by different processes and mechanisms.

The barrier islands, the ebb-tidal deltas and the tidal basins that comprise tidal channels and flats together form a sediment-sharing system. The intertidal flats in all tidal basins increased in height to compensate for SLR. The large sediment imports are predominantly caused by the damming of the Zuiderzee and Lauwerszee rather than due to response to this rise in sea level. The average accretion rate since 1926 has been higher than that of the local relative SLR. The Dutch Wadden Sea has been accreting by importing sediment from the ebb-tidal deltas and the North Sea coasts of the barrier islands.

Sustainable management of the system to ensure safety against flooding of the hinterland, to protect the environmental value and to optimise the economic activities in the area requires predictions of the future morphological development. The development of this system is under pressure of climate change and especially the associated acceleration in sea-level rise (SLR). The Wadden Sea is a unique coastal wetland containing an uninterrupted stretch of tidal flats that span a distance of nearly 500km along the North Sea coast from the Netherlands to Denmark.

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