Infiltration and Drainage Analysis in a Heterogeneous Soil by Electrical Resistivity Tomography

Abstract

Petrocalcic horizons are a common feature of soils in many regions. As a result of their presence, the soils acquire a noticeable stratified profile that may severely restrict water infiltration. Therefore, assessing infiltration and drainage becomes a complex task due to the heterogeneous nature of these kind of soils. In the present study, infiltration and drainage were evaluated by means of electrical resistivity tomography (ERT) in a Paleudol soil with a petrocalcic horizon at 90 cm depth. A field infiltration test was performed on an 11.2-m-long transect that was implemented with tensiometers and time domain reflectometry (TDR) probes. Successive measurements using ERT allowed determining resistivity changes as infiltration progressed. Resistivity values were converted into soil water content values by means of functions obtained after laboratory experiments. The soil water contents calculated were validated with the numerical modeling of pressure heads and with TDR water contents. The results showed soil horizon heterogeneities and the behavior of the preferential flow of water. These results further demonstrated the strong control that petrocalcic horizon heterogeneities exert on the water flow at field scale. Less indurated zones favored preferential flow to develop.