Electrical resistivity tomography was used in Beauce (France) to assess the
water extraction by corn plants (evapotranspiration). The acquired pseudos
ections show conductive anomalies under the plants. A 2D inversion of measu
rements led us to identify clear resistive features associated with the wat
er losses under the corn-plant rows. New models have been calculated with t
wo different 3D algorithms (finite-difference and moment-method) to take in
to account 3D structure of the ground and to confirm that periodic resistiv
e features may generate shifted apparent-resistivity anomalies.