Rapid Estimation of Volumetric Groundwater Recharge in the Vadose Zone via Ground Penetrating Radar

Abstract

Saturation in the vadose zone is known to reduce the ground penetrating radar (GPR) electromagnetic wave velocities. We examine the impact of increased water content in highly-permeable beach and dune systems on GPR velocities along coastal margin of Perth, Western Australia. We acquire repeat GPR transects in May and August before and after annual high rainfall periods. The assumption of exceedingly flat water table reflector permits us to estimated change in GPR velocity at successive dates. This change in velocity can be translated to an estimated change in water saturation via the Topp relationship which is an imperial mapping of water saturation to dielectric permittivity.