application of electrical resistivity prospecting in waste water management: a case study (kharga oasis, egypt)

Electrical resistivity technique has been used to detect the subsurface stratigraphy and structures around Kharga Oasis, Egypt. 1D inversion approaches have been applied to interpret the electrical data obtained along 10 vertical electrical soundings (VES) using electrode spacing from 3 to 400 m. A preliminary quantitative interpretation of the vertical electrical sounding curves was achieved firstly using two-layer standard curves and generalized Cagniard graphs. The manual models were used as initials to prepare the final model using the algorithm IPI2Win program. Model results were used to construct a geoelectrical section. Three geoelectric units were identified: the superficial geoelectrical layer is composed mainly of sand and gravel with relatively high resistivity values (8–372 ohm m) and low thicknesses (0.523–4.92 m). The age of this layer is from late Pleistocene to Holocene (Quaternary deposits). The second geoelectrical layer is composed of shale (Dakhla Shale). It is characterized by relatively very low electrical resistivity values (0.3–4.92 ohm m). The maximum depth to this layer ranges from 13.8 to 45.7 m. The third layer represents the first Nubian Sandstone aquifer with moderate electrical resistivity values (23.9–233 ohm m) detected at the maximum depth of penetration, a great contrast for values according to the lithological content.