Estimation of Saturated Hydraulic Conductivity during Infiltration Test with the Aid of ERT and Level‐Set Method

Abstract

Core Ideas A new technique for estimating the saturated hydraulic conductivity is developed. It uses a combination of hydrogeophysical and numerical methods. Electrical resistivity tomography and the instantaneous profile method are used. The technique is validated using simple and complex numerical hydrogeological models. Many hydrogeological and geophysical tools have been developed to determine subsoil properties, but they are often limited by sparse datasets and by the portability of the method from one site to another and often underestimate the complexity of the medium. We present a saturated hydraulic conductivity (Ks) estimation scheme, named the KES method, based on hydrogeophysical and numerical methods. The targeted medium of investigation is an unsaturated and heterogeneous soil. Estimation of Ks is accomplished by estimating the position of the wetting front and the distribution and velocity of flow lines during an infiltration test. Using numerical modeling, Ks is determined by minimizing the velocity difference between the measured flow lines and the modeled flow lines. Surface and buried electrodes are used as part of the electrical resistivity survey in determining the position of the wetting front. An instantaneous profile method is used to determine the water retention curve of the medium. The KES method has been tested and validated using data produced from simple and more complex geological models from published case studies. We obtained good reconstruction of the saturated hydraulic conductivity. We have found that the estimated value of Ks in log scale has a mean error <2.5%. Error increases along the boundaries of different hydrofacies.