Quantitative assessment of groundwater resources using airborne electromagnetic remote sensing

High-resolution airborne electromagnetic (AEM) remote sensing data have been used for the quantification of hydrological properties of a catchment-scale clay-sand-gravel aquifer. The AEM data have been integrated with limited ground-based electrical resistivity and borehole data to infer the sub-surface electrical conductivity distribution. By using theoretical models to connect microscale electrical properties with macroscale conductivity inferred from the AEM data, it is possible to estimate the in situ porosity distribution in clay-sand-gravel mixtures after calibration with measurements of cation exchange capacity, grain size distribution and pore fluid salinity at a borehole. The approach provides constraints on the estimation of a three-dimensional hydraulic conductivity distribution at catchment scale using models linking grain size distribution, porosity and electrical conductivity with hydraulic conductivity. The AEM data have assisted with the identification and quantification of groundwater resources in a clay-sand-gravel aquifer but require calibration even if this consists only of limited surface electrical resistivity, electromagnetic and hydrogeological data.