Self Potential Tomographic Technique to Detect Soil Water Movements in the Vadose Zone: Laboratory Measurements

In this work we present the first results of a controlled experiment carried out for evaluating the capability of SP technique for water fluxes detection in the vadose zone. The aim of the research is to improve the detection of water fluxes in the vadose zone by using a self-potential tomographic technique which gives a 4D (3D + time) high resolution image of water movements within the soil subsurface. Several water infiltration experiments were performed in both field and lab conditions. In this case, particularly, the experiments were performed by using a sand box (7.0 x 3.5 x 2.0 meters) which allows to be reproduced a medium-large scale natural environment. SP signals were recorded continuously by using an array of 32 unpo-larizable electrodes connected to a multiplexed high impedance and resolution multimeter. Better results came out from laboratory experiments where most of the so called cultural noise was reduced at a negligible amount. The results have proved that SP tomographic images represent a good tool for monitoring the changes of water fluxes in the vadose zone under the boundary conditions which are discussed in the work.