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Recently, the use of salt marshes in front of hard structures is increasingly proposed as a more sustainable coastal protection measure. Yet, salt marsh restoration and creation is often hampered by the lack of a thorough understanding of initial vegetation establishment. Recent studies highlight the importance of bed level change for salt marsh development. In this study we continue the examination of the impact of bed level change on salt marsh development, focussing on the prediction of salt marsh establishment and the implications for coastal management. First, a test with Spartina anglica seedlings (Cordgrass) in a wave flume showed that long-term (seasonal) bed level change is more important for seedling survival than direct wave impact at the shoot. Therefore, we subsequently incorporated bed level change in the Windows of Opportunity (WoO) framework. Lastly, this revised WoO framework was applied to the design of the Marconi pioneer salt marsh (The Netherlands). Combining the WoO framework with a morphodynamic model (Delft3D) showed its potential for salt marsh design. The framework can be used to determine whether salt marsh establishment is possible, to find out which conditions are limiting establishment and to design engineering measures creating the conditions that facilitate salt marsh establishment.

Worldwide, buildings are present at the beach and in the dunes for recreation or habitation. Their presence can affect the beach-dune development, because they affect the airflow and Aeolian sediment transport in their surroundings. This might eventually have repercussions for coastal safety. We start examining these effects by studying the local sedimentation and erosion patterns around buildings. Hereto, we placed scale models of buildings on the beach. The sedimentation and erosion patterns around the models were measured using structure-from-motion photogrammetry. In general, the air flow around bluff bodies like buildings forms a horseshoe vortex. This creates deposition and erosion patterns in a horseshoe shape. For nearly all scale models, the upwind part and downwind tails of the horseshoe showed deposition. The horseshoe deposition at the building sides was sometimes visible, also depending on building orientation. Frequently, smaller erosion and/or deposition areas also developed between the horseshoe deposition and the building.

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