WadSed

WadSED is a NWO funded research project in the Wadden Sea and Western Scheldt enhancing knowledge in system dynamics and sediment management under climate change. Within this project, the one PhD student at WUR will work on salt march survival.

Stakeholders of estuaries and tidal basins are faced with challenges of silting up of ports and waterways and rapidly shifting channels that destabilize waterways and dikes. Dredging costs for navigation are rapidly rising to untenable levels, but high long-term sedimentation is needed to keep up with sea level rise (SLR). The Wadden Sea is a UNESCO World Heritage Site where SLR in the early 22nd century (RCP8.5) will drown about half the valuable habitat that is essential for migratory bird foraging, and enhances coastal safety against storms. Key in these conflicting functions is sediment: is there enough, too much, or insufficient sediment; how fast is it moving or must be moved towards preferred locations; and how will this change in the future? The fundamental scientific problem is to understand and quantify rates and patterns of sand and mud transport and biogeomorphic interactions along the scale cascade from channel-flat unit to entire tidal system. WadSED will take advantage of similarities between the Wadden tidal basins and the Ems and Western Scheldt estuaries.

Aims
WadSED will develop innovative tools for data analysis and provide improved and new numerical models valid for these diverse tidal systems. Contrary to present digital technology, our novel tools will cover all spatial and timescales (from weeks to a century). New big data tools will enable extraction and quantification of channel-flat dynamics and objective channel networks. Models will be innovated to include sand, mud, and interactions with biota, capable of predicting present dynamics and future development under SLR. Desired impacts of WadSED are that expert stakeholders apply our leading-edge tools and numerical models, and non-expert stakeholders make informed decisions on short- and long-term development in and around tidal systems, based on our co-created knowledge and state-of-the-art participatory governance.

Individual projects
Salt marshes play a vital role in estuaries and coastal lagoons, by offering intertidal storage space that influences the tidal prism and tidal asymmetry. Survival of salt marshes depends on feedbacks between plant growth and sediment accumulation, which in turn are governed by marine boundary conditions. On a global scale, these boundary conditions are subject to changes dominated by SLR and intensified storms. Storms play an ambivalent, understudied role in the salt marsh sediment balance by delivering sediment and cause lateral salt marsh erosion. Detailed processes controlling the long-term residual sediment exchange between salt marshes and the adjacent tidal basin are still poorly understood. Consequently, it is unclear whether salt marshes will act as a source of sediment, or as a sink.

The PhD candidate will take up the challenge to simulate and predict salt marsh development governed by changing boundary conditions and human influence, and, ultimately, to determine prerequisites for salt marsh survival and the resulting coastal protection.