Observation of Infiltration Processes by 3D- ERT Measurements: Results and Problems

At two sites 3D electrical resistivity tomography (ERT) is used to study the process of infiltration of water through the soil. After the infiltration the sites are excavated and the water content and the water tensions are measured. Characteristic reference functions are derived and these will be fed into a soil water transport model aiming at remodelling the infiltration experiment. The soil type at the field sites is podsol under a plough layer. For the first experiment 110 l of water is infiltrated within 4.6 h on an area of 1.6m x 0.4m. The ERT inversion shows that about 1 day after the infiltration 46 l of water has reached the groundwater table (1.7m). During the second experiment 80 l of coloured water is infiltrated on an area of 1m x 0.4m within 8 h. The ERT inversion reveals that the water is kept relatively close to the surface for the first three hours. Then the infiltration plume moves deeper and seems to come close to the groundwater table (3.2m) 8 h after the start of the infiltration.