This velocity is influenced by the electric properties of the soil water content, mainly by the dielectric permittivity (蔚). The soil electrical conductivity (蟽), which also depends on the soil water content, can be accounted for by electromagnetic (EMI) induction prospecting. A procedure was proposed to thoroughly characterize a circular ditch system by inverting the apparent electrical conductivity (蟽a) measurements from a multi-receiver EMI instrument based on GPR profile data. A fitting procedure allowed to calibrate both the propagation speed of the GPR waves up to the interface between the ditch infilling and the underlying sand and the conductivities of both layers. Integrating the simultaneous EMI measurements and high-resolution GPR depth profiles and - slices improved the non-invasive dimensioning of the circular ditch system.