Geophysical Research Letters

Hysteresis of the self-potential response associated with harmonic pumping tests



[1] Harmonic pumping tests performed in an unconfined aquifer are responsible for a non-linear and phase shifted behavior of the self-potential response recorded at the ground surface with respect to the change in the pressure heads of the aquifer. The observed non-linearity of the transfer function can be reproduced with a petrophysical model in which the permeability, the capillary pressure curve, and the streaming potential coupling coefficient are modelled inside a unified framework approach based on the van Genuchten parametrization including a hysteretic behaviour with the water saturation. The field equations for the hydraulic heads and the self-potential signals are solved with a finite-element code, which is used to compute the time variation of the self-potential variations over time for two numerical experiments accounting or not for hysteresis. Only the model with hysteresis can reproduce the field observations.