Estimation of hard rock aquifers hydraulic conductivity from geoelectrical measurements: A theoretical development with field application

Based on the analogy between Darcy’s law for groundwater flow and Ohm’s law for electric current flow, a methodology has been developed to estimate the hydraulic conductivity and transmissivity of hard rock granite aquifer from geoelectrical parameters. The common parameter, aquifer thickness (t), has been used to combine the two relations and form an analytical equation. Mathematical relation shows a negative correlation between hydraulic conductivity and aquifer resistivity, and a positive correlation between transmissivity and longitudinal conductance. The methodology has been calibrated and validated in hard rock granite aquifers in India. The good agreement between aquifer hydraulic conductivity (K) and transmissivity (T) obtained from the resistivity sounding parameters and those obtained from pumping test analysis proves the potentiality of the methodology. It has been applied to estimate the K and T from the surface electrical resistivity parameters and results were utilized to prepare the K and T maps of Maheshwaram watershed in hard rock terrain in India.