Numerical Investigation of Distortions due to Quadripole Acquisition Time during ERT Monitoring of Leachate Injection in Landfills

Surface electrical resistivity tomography (ERT) has been used to monitor resistivity variation during infiltration process including leachate injection in Municipal Solid Waste (MSW) experiments with a relative success. Today, ERT inversion has been improved by some advanced procedures, but the impact of quadripoles acquisition time compared to the grown up rate of the affected infiltration surface is often evicted This paper highlight, by a classical numerical modelling approach, that distortions induced by the measurement may occur during ERT monitoring infiltration. This study was done on hypothetical resistivity model and on resistivity model derived from hydrodynamical modelling of a leachate injection experiment. We show that, even with advanced inversion procedure, some distortions on bulb geometry and resistivity artefact can exist. Even if complementary studies are necessary to characterize distortions created in various flow configurations, this study put forward that the ERT data acquisition sequence and electrode array should be carefully chosen to minimize distortions when studying very fast infiltration processes, as observed in leachate recirculating MSW landfills.