Combined application of electrical resistivity and GIS for groundwater exploration and subsurface mapping at northeast Qattara Depression, Western Desert, Egypt

AbstractThe study area is located at northeast of Qattara Depression, Western Desert, Egypt. Geoelectrical resistivity method has been used by measuring twelve vertical electrical soundings using Schlumberger configuration with AB/2 spacing ranging from 1.5m to 500m in order to investigate the shallow groundwater aquifer and to delineate the subsurface structures in this area. The results revealed that the subsurface section consists of three geoelectrical units. The first unit is composed of surface Quaternary wadi deposits with resistivity values ranging from 248 to 1378Ohm.m. and thickness ranging from 5.9 to 34.6m. The second geoelectrical unit is composed of sandstone of Moghra Formation (Lower Miocene) with depth ranges from 5.9 to 34.6m and its resistivity values range from 23 to 188Ohm.m. This unit represents the main aquifer in the study area. The third geoelectrical unit is composed of claystone of Qattrani Formation with depth ranging from 106 to 174.4m and resistivity values range from 0.5 to 9Ohm.m. It extends to the maximum depth of penetration at the central part of the study area.Structurally, the study area is affected by two probable faults trending mainly in NW-SE direction with upthrown side towards the central part of the study area forming a horst structure