Geoelectrical analysis for evaluating the groundwater characteristics of wadi El Madamud Area, Southeast Luxor, Egypt

Abstract

In this work, the totally 31 Vertical Electric Soundings (VESes) were carried out at wadi El Madamud, Southeastern Luxor city. These are processed and interpreted the forms of geologic models composed of five geoelectric layers of varying resistivities, lithologies, depths and thicknesses. They are surfacial unconsolidated dry silts, sands and gravels, consolidated silts, sandy gravels, sandstone and clay saturated with water, clay with unsaturated sand intercalations and chalky limestone with chert bands. The surficial layer, dry silts, sands and gravels layer (Quaternary) is cropped out on the surface of the whole area with a very small thickness range (0.5-2.2 meter (m.)) and average thickness 1.1 meters. The surficial layer, Unconsolidated wadi deposits composed of silts, sands and gravels which show the highest resistivity range (3073-90,581 Ω.m.) with average value 27,968 Ω.m. throughout the whole study area. The consolidated silt, sandy and gravels is the second geoelectric layer, which has decreasing resistivity values than the first layer. Thickness of the second geoelectric layer ranges from 1–14 meter. The third geoelectric layer is sandstone and clay saturated with groundwater, which has resistivity range from 4 to1887 Ω.m. and average value 234 Ω.m. and thickness range from 18 to 41 meters with average 21.3 meters. The main target is the shallow aquifer which represented in third geoelectric layer. The clay with unsaturated sandstone intercalation is forth geoelectric layer and has resistivity range from 11 to 10,700 Ω.m. and thickness ranges from 44 to 83 m. The last geoelectric layer is the chalky limestone with chert band, having a wide resistivity range (264–37,045 Ω.m.) with non-defined thickness. The thickness and true resistivity maps of the different layers and 2D geoelectric cross sections are generated for the represented layers to delineate their spatial distribution. The aquifer hydraulic characteristics; such as hydraulic conductivity and transmissivity within the salty aquifer, as well as the groundwater quality (salinity) are estimated, utilizing the true resistivity values acquired on the surface through the geoelectric resistivity survey.