Impacts of temporal variations in sediment availability on the long-term ability of coastal salt marshes to adapt to global sea level rise

• Applicant: Dr. Mark Schürch
• Subject Area: Physical Geography ; Palaeontology
• Term: from 2015 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 272052902

The proposed project aims to investigate how the morphological development of coastal salt marshes along tidally influenced coasts responds to the expected future global sea level rise (SLR) and possible changes in storm activity. Previous research has shown that coastal salt marshes in most places around the world are able to adapt to low and moderate SLR scenarios but will likely disappear under constantly accelerating or very high SLR scenarios. Tidal range and sediment supply have been identified as the most important parameters affecting the adaptive capacity of coastal salt marshes to rising sea levels. Sediment supply is the result of a chain of complex interactions taking placing in the coastal environment. It strongly depends on external sediment sources, originating from riverine sediment input and coastal erosion, for example, and local intertidal sediment dynamics, which are subject to large temporal and spatial variability and take place in close vicinity of the coastal salt marshes. To a large extent, temporal variations in local sediment characteristics and storm activity are responsible for the variability in sediment delivery to the salt marshes. The major hypothesis of the proposed project is that predictions for the future development of coastal salt marshes are strongly influenced by temporal variations of sediment availability. The project aims to investigate how temporal variations in the near-field external sediment supply and the intertidal sediment dynamics influence the sediment supply of the marshes and their future long-term development. The major driver for such temporal variations is assumed to be changes in the local storm climate, inducing increased hydrodynamic energy along the coast and on the intertidal flats, hence, increased sediment transport. A special focus is put on the impact of waves and currents as well the prevailing water level that may control the amount of sediment being supplied to the coastal salt marshes. An extensive field campaign will be conducted to collect data on the prevailing sediment dynamics at the example study site Freiston Shore (UK East coast), which has previously been extensively investigated by the host institution. A wide range of state-of-the-art measurement devices will be employed to monitor the near-field external sediment supply, the sediment dynamics on the intertidal flat, and the resulting sediment supply of the marsh for a period of one year. The collected data will be used to develop a coupled salt-marsh model for simulating how decadal variations in storm activity affect the sediment supply of the salt marsh and its vertical growth. Simulation runs will be performed using a wide range of sea level rise (SLR) and storm climate scenarios to assess how these changes influence the ability of coastal salt marshes to adapt to future SLR.

• DFG Programme: Research Fellowships
• International Connection: United Kingdom
• Host: Dr. Tom Spencer