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We discuss a strategy capable of a quantitative long‐term monitoring of water saturation and volume variation of light non‐aqueous phase liquids in the soil. The goal was reached monitoring a controlled sand cell contaminated with classical gasoline over 124 days, using geophysical methods such as electrical resistivity tomography, induced polarization and ground penetrating radar. We show that empirical relations, linking the water saturation to the physical parameters measured as resistivity from electrical resistivity tomography and travel time from georadar with advanced processing, are good tools for this purpose. The consistence of the proposed process is validated by both good overlap of results carried out from electrical resistivity tomography and georadar and theoretical models simulating the actual experiment. [ABSTRACT FROM AUTHOR]

ABSTRACT In this study, a new two-dimensional inversion algorithm was developed for the inversion of cross-hole direct current resistivity measurements. In the last decades, various array optimisation methods were suggested for resistivity tomography. However, researchers have still collected data by using classical electrode arrays in most cross-hole applications. Therefore, we investigated the accuracy of both the individual and the joint inversion of the classical cross-hole arrays by using both synthetic and field data with the developed algorithm. We showed that the joint inversion of bipole-bipole, pole-bipole, bipole-pole, and pole-tripole electrode arrays gives inverse solutions that are closer to the real model than the individual inversions of the electrode array datasets for the synthetic data inversion. The model resolution matrix of the suggested arrays was used to analyse the inversion results. This model resolution analysis also showed the advantage of the joint inversion of bipole-bipole, pole-bipole, bipole-pole, and pole-tripole arrays. We also used sensitivity sections from each of the arrays and their superpositions to explain why joint inversion gives better resolution than the any individual inversion result. [ABSTRACT FROM AUTHOR]