A Coupled Electrical Resistivity–Infiltration Model for Wetting Front Evaluation

Abstract

A coupled resistivity–infiltration model was developed. The infiltration model relies on the analytical solution of a fully developed and sharp wetting front using the Green–Ampt approximation, thereby reducing the resistivity model to the simple two‐layer case. The Green–Ampt approximation is a highly simplistic soil model that has limited applicability to real soils. The forward model demonstrates the effects of a voltage drop with time for a pole–pole, Wenner, and dipole–dipole electrode arrangement for a moving wetting front. The velocity of the wetting front can be obtained directly from the time series curve by normalizing the measured apparent resistivity to the resistivity of the wet layer (estimated from the voltage at time t = ∞) and plotting against the reciprocal of time multiplied by the electrode separation. Furthermore, if the cumulative infiltration or other parameters are known, then the hydraulic conductivity can be calculated.