Numerical and Experimental Mapping of Root Zone Using Surface and Borehole Resistivity Tomography

The global water shortage in terms of quality and quantity demands a sustainable management of water and land use which in turn demands a better mapping of roots and monitoring their process. Generally, roots can be divided in soft, fine branches that cause electrically conductive anomalies and thick, isolated branches that produce electrically resistive anomalies within the soil material. Electrical resistivity tomography at the ground surface and in boreholes allows mapping root zones. But the resolution generally increases by increasing number of measurements and accordingly the time and costs. We numerically tested different non-standard, standard and the new approach of optimised electrode configurations in different survey designs. We have studied the resolution of the different configurations to find the optimum dataset of practical size and high resolution. We have applied forward and inverse modelling of different setups on 2D models of the root zone with conductive/absorbing and resistive/transporting roots, respectively. The best resulting models are presented and discussed as a function of the different applied configurations and survey designs.