The Dutch coastal zone is prone to flooding. The Netherlands has chosen to protect the coast by means of soft adaptive solutions such as (mega) nourishments with the aim of maintaining the coastline. At present the sediment volume in the Wadden Sea coastal zone is insufficient due to the export towards the tidal basins. This is exacerbated by the accelerated sea-level rise and subsidence and subsequently larger nourishment volumes are requiered in the near future. Mega-nourishments like the Sand Motor turned out to be efficient. However, the morphological and ecological impacts of such a large-scale intervention in a complex system as the ebb-tidal delta of the Wadden Sea are insufficiently known. This is all the more critical, as the anticipated mega-nourishments will be in the vicinity of the protected World Heritage area. Within SEAWAD, we develop the system knowledge and tools to predict the effects of mega-nourishments on morphology and ecology (benthos distribution).
Tidal flats are worldwide at risk due to human disturbances and climate change. These habitats sustain coastal food webs and provide essential ecosystem services such as coastal protection. Their conservation and restoration is a major coastal management issue. For example, ‘soft’ measures like sand nourishments and ‘hard’ measures like biogenic reef structures are being proposed and experimented with to mitigate the loss of tidal flats in the Oosterschelde (SW Netherlands). However, the behavior of tidal flats under different external and internal forcing and their morphological and ecological response to different conservation/restoration measures are still poorly understood.
The EMRGO project provides the scientific background on tidal flat eco-morphodynamics, aiming at improving and optimizing future management of tidal flats. Two PhD students study and develop a model for tidal flats, in which hydrodynamics, sediment dynamics, geo-morphodynamics and ecology are integrated, and that evaluates the morphological and ecological effects of management measures at different scales. We make use of the different management regimes in Oosterschelde and Westerschelde, to elucidate and model large and medium scale management measures on tidal flat dynamics. In addition, we use results from running pilots (nourishment, biogenic reefs), together with newly collected data on forthcoming pilots, to evaluate the effects of local-scale mitigation measures. A postdoc integrates the scientific findings, develop guidelines and management tools and run scenarios that assess the morphological and ecological tradeoffs of different management strategies and mitigation measures. This is being done in close collaboration with our non-academic partners.