Geoelectrical applications for groundwater exploration in El-Marashda area, Qena, Egypt

The study area is bounded by latitudes 255 and 26 10 N and longitudes 32 and 3240 E. It lies to the southwest of Qena city across the western banks of the Nile River. The investigated area is classified into four main geomorphological units These units are distributed from south to north as follows the limestone plateau the drainage basins pediment plains and the River Valley and agricultural lands. The investigated area comprises surface and subsurface stratigraphic rock units ranging in age from Lower Eocene to Recent. The applied 2-D resistivity imaging was carried out to using Wenner electrode configuration to identify the reasons of water logging in some parts in the study area The obtained results show low resistivity values ranges from 3.5 to 6.0 Ohm.m along the subsurfaceof 2-D image this suggest increases in water content near surface that is full water saturation and attributed to lower permeability is due to the effect of the lithologic composition clay rich alluvium fully saturated and lower degrees of infiltration downward in the water logging parts in the investigated area. The interpretation results of the geoelectrical resistivity sounding measurements using Schlumberger electrode array in the study area led to the detection of three water bearing layers the first one has resistivity values range from 20 to 98 Ohm.m and consists of sand silt and clay intercalation water bearing The thickness of this layer is varies from 11.5m to 54m. The second water bearing layer extends at the western part of the study area has resistivity values ranging from 35 to 115 Ohm.m it consists of sand water bearing The thickness of this layer ranging from 20 to 30 m. The thrid water bearing layer consists of fractured limestone water bearing it has resistivity values ranging from 110 to 270 Ohm.m. The obtained geoelectrical layers show general decrease in thickness towards south and southeast. The geoelectrical profiles revealed that the subsurface succession have been affected by five normal faults.