Barrier islands, formed by the energy of wind, currents and waves are fragile ecosystems. Morphodynamic changes of barrier islands and the consequences for soils and underlying freshwater reservoirs are of major interest for coastal environments and the drinking water supply in coastal areas. Starting as a flat and bare sand flat, the young „Ostplate“ changed within only 80 years to an area covered with vegetation with a elongated west-east running line of high dunes, below which freshwater reservoirs have already formed. This evolution is well documented with aerial images and vegetation maps. The aim of this project is to study the initial pedological and hydrogeological processes associated with the geomorphological changes within a known timeframe. Initial soil developing processes and the chronosequential alterations of the soils from the dunes, salt marshes and central flat sands will be investigated as well as the weather and inundation induced variability for the latter. Thickness, extent, age and dynamics of the freshwater reservoirs will be studied and both past evolution as well as future development will be evaluated by means of numerical modeling. In addition, the hydrochemical processes along a flowpath from infiltration into soils to submarine discharge within the freshwater body will be investigated. The protected „Ostplate“, largely undisturbed by humans, is an ideal site for the planned study, as the timescales of the dynamic evolution are known. The fact that the “Ostplate“ is not a barrier island by itself is irrelevant with regard to pedological and hydrogeological processes.

Soil Sciences, IBU, University of Oldenburg

Geoecology, ICBM, University of Oldenburg

Deutsche Forschungsgemeinschaft (DFG)

2015 - 2019

Dr. Tobias Holt

Dr. Stephan Seibert

Seibert, S.L., Böttcher, M.E., Waska, H., Holt, T., Pollmann, T., Massmann, G. (2021). Hydrogeochemistry of near-surface groundwater on a developing barrier island (Spiekeroog, Germany): The role of inundation, season and vegetation. Journal of Hydrology 597, 126139.

Holt, T., Greskowiak, J., Sültenfuß, J. and Massmann, G. (2021). Groundwater age distribution in a highly dynamic coastal aquifer. Advances in Water Resources 149, 103850.

Holt, T., Greskowiak, J., Seibert, S.L., Massmann, G. (2019). Modeling the evolution of a freshwater lens under highly dynamic conditions on a currently developing barrier island. Geofluids, Article ID 9484657, www.hindawi.com/journals/geofluids/2019/9484657/

Seibert, S.L., Greskowiak, J., Prommer, H., Böttcher, M.E., Massmann, G. (2019). Modeling of biogeochemical processes in a barrier island freshwater lens (Spiekeroog, Germany). Journal of Hydrology 575, 1133-1144

Seibert, S.L., Böttcher, M.E., Schubert, F., Pollmann, T., Giani, L., Tsukamoto, S., Frechen, M., Freund, H., Waska, Simon, H.H., Holt, T., Greskowiak, J., Massmann, G. (2019). Iron sulfide formation in young and rapidly-deposited permeable sands at the land-sea transition zone. Science of the Total Environment 649, 264-283

Seibert, S.L., Holt, T., Reckhardt, A., Ahrens, J., Beck, M., Pollmann., T., Giani, L., Waska, H., Böttcher, M.E., Greskowiak, J., Massmann, G. (2018). Hydrochemical evolution of a freshwater lens below a barrier island (Spiekeroog, Germany): The role of carbonate mineral reactions, cation exchange and redox processes. Applied Geochemistry 92, 186-208

Holt,T., Seibert, S. L., Greskowiak, J., Freund, H., Massmann, G. (2017). Impact of storm tides and inundation frequency on water table salinity and vegetation on a juvenile barrier island. Journal of Hydrology 554, 666–679