Coastal groundwater systems: mapping chloride distribution from borehole and geophysical data

Abstract Information on chloride (Cl) distribution in aquifers is essential for planning and management of coastal zone groundwater resources as well simulation validation density-driven models. We developed a method to derive concentrations from borehole information helicopter-borne electromagnetic (HEM) data the aquifer Elbe-Weser region where observed electrical conductivity reveal that horizontal salinity not uniform does correlate with coastline. The integrated approach uses HEM resistivity data, petrography information, grain size analysis samples estimate Cl distribution. approch straightforward due complex nature geology clay silt are present. Possible errors uncertainties involved at different steps discussed.