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Monitoring Hydraulic Experimfnts By Complex Conductivity Tomography
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 10th EEGS Symposium on the Application of Geophysics to Engineering and Environmental Problems, Mar 1997, cp-204-00076
Abstract
Complex electrical conductivity tomography has been applied to monitor hydraulic experiments<br>in a research facility for in-situ remediation of contaminated soils and aquifers.<br>Arrays of electrodes were installed in a flume where infiltration experiments with non-aqueous<br>phase liquids (NAPL) were performed. Data sets of about 500 configurations have been acquired<br>with a computer-controlled equipment for spectral induced polarization.<br>The tomographic algorithm used for interpretation is based on the simultaneous iterative<br>reconstruction technique (SIRT). As in other inversion techniques, the Jacobian or sensitivity<br>matrix has to be known. The three-dimensional forward modelling is performed by the ftite<br>difference method using complex values of conductivity and potential.<br>The resulting tomographic images show the distribution of complex conductivity inside the tanks.<br>They reflect both the spatial variability of soil and aquifer properties and changes between<br>different stages of the experiments. These images were successfully used to determine the state of<br>the multiphase system consisting of silicate matrix, water, NAPL and air.