Electrical resistivity tomography for delineating groundwater potential zones in fractured metasedimentary rocks, Lesser Himalayas, Pakistan

Abstract Geological discontinuities such as faults and fractures occur in all kinds of rock terrains. Investigation of these discontinuities is important in understanding the geological structures and their potential for groundwater accumulation. In the present study, the surface geology, electrical...
Ausführliche Beschreibung

Abstract Geological discontinuities such as faults and fractures occur in all kinds of rock terrains. Investigation of these discontinuities is important in understanding the geological structures and their potential for groundwater accumulation. In the present study, the surface geology, electrical resistivity tomography technique and borehole datasets were integrated to delineate fracture zones in meta-sedimentary rocks of Malakand, northern Pakistan. Six electrical resistivity tomography (ERT) profiles were acquired using multi-electrode imaging system by adopting Wenner–Schlumberger electrode configuration having 5 m electrode spacing attaining a maximum spread length of 300 m. Three dominant zones of variable resistivity were identified, i.e., the top layer mostly comprised of dry surficial deposit (clay, silt and sand) followed by deformed meta-sediments until bedrock is achieved. The results revealed highly fractured and low resistivity zones surrounding the bedrock of Saidu Formation and Malakand granite. The identified buried fracture zones were associated with east–west trending thrust patterns (controlled by local tectonics). These fractures serve as zones for potential groundwater accumulation/recharge and provide sustainable water resources for the local community. Furthermore, 2D electrical resistivity tomograms have also provided an insight into structural complexity, dipping towards north and south bounding local reservoirs. The techniques used in this study could be opted for other adjacent regions with similar subsurface geological conditions to demarcate the groundwater potential zones. Ausführliche Beschreibung