Estimating saturated hydraulic conductivity from ground-based GPR monitoring Porchet infiltration in sandy soil

Abstract

In this study we present a Porchet infiltrometer experiment monitored by a Ground Penetrating Radar (GPR). The modeled radargram is compared with experiment and a first step into retrieving hydraulic parameters is shown. The experiment was carried out in a quarry of Fontainebleau sand, using a Malå RAMAC system with antennae centered on 800 MHz. Numerical models of the infiltration were made using SWMS-2D, numerical GPR data of the infiltration were computed using GprMax suite of programs. We generated 2D water content profiles associated with a set of Mualem-van Genuchten parameters, at each experimental time step with SWMS-2D. Then we converted those profiles to 2D permittivity profiles using the Complex Refractive Index Method relation, to solve the Maxwell's equation using GprMax2D. We found that on ground surface GPR is sensitive to the shape of the bulb and to variations of the Mualem-van Genuchten parameters. We propose a first step into an inversion of the saturated hydraulic conductivity by comparing the experimental and modeled two way travel time of the reflection on the top of the infiltration bulb.