Evaluating Ground-Penetrating Radar use for water infiltration monitoring

International audienceGround-Penetrating Radar (GPR) was tested to monitor water infiltration in sand. Water was injected down an 81 cm long tubed hole, with a piezometer recording the depth of water and a tap valve used to adjust it to 15 cm ± 2 cm above the bottom of the tube. During the 20 minutes of infiltration a GPR system recorded a trace every second with its transmitter and receiver antennae at a fixed offset position on the surface. The signal, enhanced by differential correction, allows for tracing the evolution of top and bottom limits of the water bulb in space and time. Comparison with hydrodynamic model of the infiltration process and simulated radargrams prove that the GPR reflections trace the wetting front and the saturation bulb. A quantified estimation of the evolution of the top border of the wetting zone is provided