Characterization of spatial and temporal soil water status in vineyard by DC resistivity measurements

We performed a DC resistivity monitoring experiment during eight months in 2003. Low, medium and high resolution measurements have been carried out at various locations of a vineyard. General apparent resistivity mapping evidences the spatial variations of the summer drying of the subsurface.
Three experiments have been conducted in the studied area :
– parallel 2-D dipole-dipole sections (96 electrodes at 1 meter spacing). The sections are orientated in the long direction of the studied area and located between the vine rows. After inversion, these sections allow to describe the vertical variations of the electrical resistivity and help to specify the 3D geological sketch of the studied area down to three meters.
– high resolution « borehole like » tomographic sections obtained with a custom electrode set. Three PVC rods, two of them vertically placed and one horizontal between the two vertical carry 48 stainless steel electrodes, 0.13 m spaced. This allows to investigate a 4 squared meters section with electrodes on three sides of it. Two of these devices were placed within the sudied area. Moisture measurements were performed in the investigated section with time domain reflectivity probes. High resolution cross borehole tomography shows moisture variation at the vine stock scale, and short time interval such as the diffusion af a rainfall.