Characterizing hydraulic parameters in a small-scale tank experiment, using Self-Potential, DC Resistivity and Induced Polarization methods.

Abstract

As part of a larger project that is concerned with the characterization of hydraulic parameters from electrical surface measurements, this thesis covers self-potential, DC resistivity and induced polarization measurements taken on a medium-scale setup. This writing aims to research whether it is possible to obtain hydraulic parameters (such as permeability) from transient SP experiments and from DC resistivity and IP measurements taken on a steady-state setup. This setup was constructed inside a fish tank and consisted of a bulk material of medium sand. Two sand columns were placed inside the medium sand and were of a finer and respectively coarser material than the bulk material. The transient recovery experiment has shown that the self-potential method is able to show subsurface heterogeneities. The subsurface sand columns in the experiment are even outlined by the raw SP data. A forward model for the transient SP recovery experiment was successfully built. The Pearson linear correlation coefficients between the modeled and measured data for the full $800 s$ timespan, all lie within the 0.95 to 1.00 range and have an average of +/- 0.99. The model can now be used in future inversion efforts. The DC resistance data have been corrected for four insulating boundaries. The two short-side boundaries, however, have a water reservoir. Those might have influenced the DC resistivity data. An improvement can be made in those data. The resistivity has values between 30 and 60 \textit{$\Omega$m}. The IP data roughly shows the outlines of the coarse grained column and somewhat the finer grained column in the inverted data. Following this work, the SP data should be inverted. Using inversion codes for a combination of the SP and the DC resistivity and IP data sets should enable us to obtain higher quality information about permeability distributions in the aquifer.