Primary challenge owner: Province of Fryslân
Secondary challenge owner(s): None
A large part of the Dutch coastal zone contains shallow salt/brackish groundwater. Above the saline/brackish groundwater, rainwater lenses will form. This rainwater lens is bordered at the bottom by a barrier, where the freshwater is able to pass relatively quickly to the brackish/saline water present in the subsurface. In areas with strong seepage and in dry summers, this rainwater lens can disappear (the boundary surface rises), causing agricultural crops to face saline groundwater. This has a negative effect on crop size and quality.
With the current measuring methods the displacement of this boundary (and with it the thickness of the rainwater lens) cannot easily be monitored continuously. One consequence is that, as a result, the effects of interventions in the hydrological regime cannot be properly determined.
Develop a measuring instrument, which allows continuous detailed monitoring of the course (profile) of salinity in depth.