Assessment of groundwater conditions, using electrical resistivity method: A case study from south-west Iran

This research deals with the detection of the aquifer boundaries, depth to the water table, aquifer thickness, potential zones, source of salinity and subsurface geology of the Shirin Ab Basin by simultaneous use of electrical resistivity and borehole data. In this area, due to high population, demands for new water resources are increased and the current drinking and agricultural water resources are at risk. Hundred and seventy Vertical Electrical Sounding (VES) measurements were carried out in 19 profiles by Schlumberger array configurations. The maximum distance between current electrodes (AB) set is 1000 m. The following results have been achieved in this study. 1- Study area is an alluvial aquifer, divided into north and south parts by the Khohanak Anticline. 2- Interpretation of one-dimensional (1D) inversion of measured apparent resistivity curve was used for mapping fresh and brackish water, and separation of their boundaries. 3- Good agreement between conductivity and chloride concentration in water samples indicates that the salinity is the most important factors controlling resistivity. 4- Electrical resistivity of the aquifer was calculated and is about 13-380 Ohm-m in the northern part and 4-219 Ohm-m in the southern part of the aquifer. 5-Regarding the source and course of the Shoor Ab River, and ground water flow direction, it seems that the marly-sand of the Aghajari Formation is the main source of the salinity. 6- Transverse resistivity (RT) is calculated and interpreted in terms of the transmissibility and potentiality of the aquifer.