Hydraulic Conductivity Estimation From Spectral Induced Polarisation Data – A Case History

We carried out a spectral induced polarisation (SIP) survey at the Krauthausen hydrogeological test site in Germany. Multifrequency data were recorded along two profiles, and single frequency data along ten densely-spaced profiles with a dipole-dipole configuration and 2 m electrode spacing. The data were inverted with a 2-D inversion code to obtain images of resistivity and phase distribution for each frequency. We used a focusing regularisation scheme that does not suppress sharp boundaries and yields realistic images of the subsurface. From the complex conductivity distribution we calculated the hydraulic conductivity using different empirical equations. The results obtained with the constant phase angle model are encouraging in the sense that the hydraulic conductivities have the same order of magnitude as those determined from grain size analyses. The gross structural features compare well with the known lithology, <br>which consists of an aquifer over an impermeable clay layer at approx. 10 m depth.