TIME-LAPSE ELECTRICAL RESISTIVITY TOMOGRAPHY APPLIED TO SOIL INFILTRATION

Soil infiltration plays a fundamental role in the agricultural field. Standard methodologies for determining basic infiltration rate are altered by the presence of preferential flow paths in the soil. This problem is important when it comes to intensive livestock farms where the pollutant load of effluents is high. The objective of this work was to detect and characterize possible preferential flow pathways in two situations with different degrees of animal trampling intensity: a site with pasture, with no animals present (control); and a transit site, where effluents flow from Corrals that are in a higher topographic situation. An irrigation sheet was applied with saline water during a certain time periods; simultaneously, time-lapse electrical resistivity tomography (TLERT) was used as the water flow penetrated the soil. The distribution of electrical resistivity anomalies with respect to the initial situation before irrigation (sensitive to salt water ingression), observed at different time periods, showed the advance of the solution through the porous space. In site 1 (control), water advance was characterized by a more homogeneous front; in site 2, channeling was detected with a greater and faster flow, which could have given rise to soil and groundwater contamination detected in previous studies. It is concluded that this methodology has promising results that suggest the need to deepen our knowledge in this area.