Field-scale induced polarization (IP) data remain underutilized due to the challenges of data acquisition and interpretation of the resulting observations for near surface environmental applications. We use measurements at a test site and the principle of IP reciprocity to demonstrate that the primary factor controlling the quality of IP data acquired using standard resistivity/IP imaging systems is the signal to noise ratio (SNR), i.e., the recorded signal strength. This factor favors the use of nested arrays, where one or two of the potential electrodes fall between the current electrode pair, that guarantee a high primary voltage ( V
p
) versus Dipole-Dipole type arrays where voltage differences rapidly decay away from the current injection pair. Comparison of data acquired using stainless steel, Cu-CuSO
4
porous pot and graphite electrodes demonstrates that electrode material is a significant second order factor but only for measurements where the SNR is relatively low (for the instrument used in this study when V
p
< 30 mV). We also propose a simple framework for interpretation of environmental IP datasets whereby the acquisition of IP data is used to remove the inherent ambiguity in the interpretation of standalone resistivity data such that the subsurface distribution of the surface conductivity and electrolytic conductivity contributions to the total conductivity can be resolved. We demonstrate this approach on a field site within a first order catchment where a high surface area formation likely limits vertical transport and promotes interflow. Sharp contrasts in electrical structure between the two slopes of the catchment are observed.
Recently, Wadi El Natrun and its surroundings have witnessed intensive investments in land reclamation, including the arbitrary drilling of hundreds of groundwater wells. Currently, serious hydrogeological and environmental problems have been addressed, such as groundwater quality degradation and water head drop. Electrical resistivity measurements were performed at six locations across the study area to assess its ability to reveal the heterogeneous subsurface stratigraphic and hydrogeological setting of groundwater aquifer(s). The geoelectrical results successfully reflect the current vulnerable hydrogeological setting of the study sites. The current study highlights the current practice in which farmers rely on isolated 1-dimensional vertical electrical sounding (1D VES), which is not the only exploration tool for such electrically conductive stratigraphic succession. One of the main findings is addressing the advantage of applying 2-dimensional electrical resistivity imaging (2D ERI), where it offers a more robust view of both vertical and lateral variation of the investigated subsurface section (Case 3). On the other hand, the Geographic Information System (GIS) could mirror the present groundwater potentiality status, where both GIS analysis and resistivity results coincide, and where the good potentiality zone is restricted to the west and southwest directions of the study area (area of interest (aoi)), where the resistivity values of water bearing are relatively high and lie on the main drainage (Cases 2, 5, and 6). On the contrary, poor potentiality zones are deemed because of their proximity to tiny attributers, and are characterized by low resistivity values (Cases 1, 3 & 4), Finally, the current research study demonstrates the significance of combining morphometrical analysis with geophysics techniques for such environmental problems, where groundwater is primarily controlled by geomorphological features and geological conditions, including lithology and geological structures.
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