Delineation for groundwater occurrences and potentialities

• Motivation:

The aim for which the investigation is planned and conducted is to estimate the under-groundwater potentiality and the capability to use, and consequently recommend places for future digging water wells. The field program conducted in the study area to achieve the investigation’s objectives is Electrical Resistivity Tomography (ERT) and, Earth Resistivity in form of Vertical Electrical Soundings (VES’s). Geoelectric methods are well known that can be successfully employed for groundwater investigations.

• Survey Details

The survey was conducted by 4^th Domain Geophysical Services at the studied site. It was decided that 3ERT profiles and 6 VES’s were needed so the area of will be covered probably and the potential zones will be studied perfectly as shown in figure (1). Applying the Schlumberger Wenner array which showed the best protocol to detect and get reliable result in such area.

• Result and Interpretation

The results from resistivity and chargeability have a good coherency and confirm each other in the survey the result of the three profiles indicate that there are two main geoelectric layers. This layer has a thickness ranging from 25 to 40 m and high resistivity greater than 500 ohms.m. The second layer is characterized by moderate resistivity ranging from 35- 85 ohm.m, low chargeability and, depth from the start from 20m-35m reached more than 100 m in depth this layer is saturated by water. In addition, these layers are confirmed in VES and it gave as vertical resolution reached 250m. From all data, the recommended location for drill is in the middle of profile 3 and profile 1 with 200-230m depth which allow to get the maximum out of the ground water reservoir.