Percolation monitoring and water content estimation by Ground Penetrating Radar in a controlled environment

We investigated the percolation of water within a controlled environment in order to recover the EM properties and the internal structure of the materials, and to better understand the drainage processes involved. We implemented an analogue model that accurately replicates a green roof, from the construction materials to the geometry. We acquired several common offset GPR data sets on the entire surface of the model, both before and during different irrigation tests. We separately analyzed variations in the reflected amplitudes and in the EM velocities, the latter of which were calculated by combining the measured thickness of the model with the arrival times of the recorded reflections. The signal amplitudes obtained before and during irrigation are compared in order to estimate the attenuation factor at the different stages of the irrigation process. We use the attenuation factor and the EM velocities to estimate the relative permittivity of the topsoil mixture, from which we then calculate the water content, the porosity, and the relative electrical permittivity of the solid matrix by applying well known empirical formulas. The results were validated by comparing them with independent direct measurements. (C) 2021 Published by Elsevier B.V.

Automated summary

This study investigated water percolation in a controlled environment to understand drainage processes, recover internal material properties, and quantify electromagnetic behavior. An analogue green roof model was used to collect and analyze GPR data to estimate water content and permittivity. Empirical formulas were applied to calculate porosity and relative electrical permittivity of the solid matrix, with results validated against direct measurements.