Depicting of groundwater potential in hard rocks of southwestern Saudi Arabia using the vertical electrical sounding approach

Abstract

In the hard rock terrains of southwestern Saudi Arabia, vertical electrical soundings (VES) were used to demarcate groundwater potential zones. To map the groundwater potential zones, 16 VES were done using a Schlumberger electrode array arrangement. Zond-IP computer software was used to analyze and interpret field measurements. The pseudo and resistivity cross-sections have been processed. The evaluation of the 1D geoelectrical curves revealed that the area is characterized by three geoelectrical resistivity layers. The topmost layer of unconsolidated alluvium deposits, which has a wide range of resistivities (42.28 to 297.97 Ω·m) and a thickness of up to 6 m, is the first of these layers. This range of resistivity is linked to changes in the layer's lithology and humidity. The second layer's resistivity values range from 372 to 3625 Ω·m, while the third layer's resistivity values range from 1015.37 to 21113 Ω·m. The second layer's resistivity implies fractured and weathered/jointed basement rocks, and the third layer's resistivity indicates broken to huge basement rocks. According to the findings, the worn and fractured horizons of basement rocks found in the vicinity are acceptable groundwater potential aquifers. The degree of weathering and fracture of the foundation rocks, and thus their water saturation, can be linked to vertical and horizontal variations in resistivity.