In March 2016, a groundwater monitoring transect was installed in a north-south direction on the Ostplate of Spiekeroog to investigate the simultaneous development of dunes and accompanying freshwater lenses. The observation wells were placed on the beach as well as north and south of the dune ridge. In addition, three piezometers were placed in the salt marsh south of the dunes to investigate the near-surface groundwater.
The wells were also used to investigate the extent of fresh groundwater and iron sulphide formation at the land-sea transition zone.
Groundwater levels and, in some cases, electrical conductivity continue to be measured at the observation wells.