Induced polarization as a tool to non-intrusively characterize embankment hydraulic properties

Characterizing key petrophysical parameters of dams and embankments (including water content, specific surface area or cation exchange exchange capacity, and permeability) is an important task in estimating their degree of safety. So far, induced polarization tomography has not been investigated to check if it can play such a role. We have conducted a time domain induced polarization profile along the embankment of a canal in the South East of France. The profile is 560 m long. It comprises 1696 apparent resistivity and chargeability data and was accomplished by separating the current and voltage electrode cables to improve the signal-to-noise ratio. In order to complement the study, we performed induced polarization measurements on six core samples (including a clayey material and five carbonate rocks) collected from outcrops. A petrophysical induced polarization model called the dynamic Stern layer model is tested to see how the electrical conductivity and the normalized chargeability can be both connected to the porosity, the cation exchange capacity (CEC), and permeability of these materials. Then, these results are applied to interpret the electrical conductivity and normalized chargeability tomograms into water content and CEC tomograms. In turn, these two parameters are used to compute a permeability index.