Application of Time Laps Resistivity Survey to Find the Fractured Zones

Geophysical surveys have both applications to measure time variation as much as space. Based on the scope of the study, subsurface resistivity variations with time is so important. Nosoud region is one of the most complex geological areas in the West of Iran. Different tectonic processes are made this area so complex. Flowing water into the tunnel from fractured zone is the challenging problem. In this study, effect of extraction of water with pumping from the tunnel is evaluated by time laps resistivity survey to locate fractured zones. In order to resistivity survey Wenner-Schlumberger array is used in time laps mode with three months interval along one profile. Measured data processed in both 1D and 2D mode by IPI2Win and Res2dInv softwares respectively. The results of 1D interpretations show change in resistivity value in both pseudo cross-sections and resistivity sections as result of pumping water. However, location of the fractured zone could not be resolved in 1D data processing. Here, 2D interpretation is carried out to find the exact location of this zone. Result of 2D interpretation shows positive percentage changes in resistivity that locate fractured zone that increases the hydraulic conductivity and water channeled from this zone to tunnel.