Rising saltwater, caused by either anthropogenic or natural effects, can threaten freshwater aquifers that are used for water supply. The strong resistivity contrast between saltwater and freshwater due to ion concentration allows for detecting and monitoring changes of water quality early by means of electric methods. The project SaMoLEG uses steel-cased boreholes for large-scale ERT monitoring.
The second step involved surveys on two test sites to show the feasibility of the developed method on different scales and a monitoring. An optimisation algorithm based on the sensitivities increased the information content of the surveys. A monitoring was installed on a medium-scaled test site (500x300m) with support of BLM-Storkow. Inversion was done with BERT (Günther et al., 2006). A saltwater contamination was verified and results of the monitoring showed a decreasing salinity (figure 3). Finally, the developed method was successfully applied on a large scaled 4x4 km test site.