Variations of self-potential and unsaturated water flow with time in sandy loam and clay loam soils

Accurate assessment of soil–water fluxes is essential in soil physics due to its direct implications in environmental, agronomical or hydrological applications. Field estimations of soil–water fluxes by ‘classical’ hydraulic methods are often difficult to obtain. Moreover, water fluxes are highly variable in space and time. The obtainment of a reasonable estimate for this variable would require numerous measurement sites. However, such a requirement is rarely met. Thony et al. [CR Acad. Sci. Paris, Earth Planetary Sci. 325 (1997) 317] presented the experimental evidence of a linear relationship between the self-potential (SP) and the unsaturated soil–water flux. Therefore, this relationship would allow the indirect assessment of the water flux using electrical measurements. Such an approach would appear much more flexible and easier to perform than the current hydraulic measurements. The aim of this study is to experimentally investigate the existence and robustness of the flux–SP relationship for different soil types and pedoclimatic conditions.