Abstract

WEINZETTEL, Pablo; VARNI, Marcelo; DIETRICH, Sebastián  and  USUNOFF, Eduardo. Evaluation of electrical tomography arrangements to identify petrocalcic layers in soils. Cienc. suelo [online]. 2009, vol.27, n.1, pp.135-146. ISSN 1850-2067.

The electrical resistivity tomography (ERT) is an important tool in the characterization of the soil and in the infiltration and/or contamination processes. Its constant development through the improvement of equipment to obtain data as well as that of the inversion programs for interpretation makes its use more frequent in the study of soils and aquifers. The investigations of multielectrodic devices that will be more suitable for each particular case is relevant to obtain satisfactory determinations, therefore in this case the results of the electrical tomography application are presented with different arrangements to study the soil will the presence of petrocálcico horizons. Nine ERT were carried out over a soil with shallow levels of petrocalcic layers. The tomographies were obtained by means of a resistivimeter with 56 electrodes 30-cm apart. Such an arrangement was laid out along three transects. At each transect, the multi-electrode arrangement Wenner, Schlumberger, and dipole-dipole were applied. The results were interpreted by means of an inversion computer program. Comparisons among the methods applied were able to assess their advantages and drawbacks and to define the method that better fits the study of soils with petrocalcic layers by means of electrical tomography. The conclusion is that the Schlumberger and Wenner methods discriminate the horizontal layers better, whereas the Dipole-Dipole method is much more time-consuming, and is very sensitive to the electrode contacts. On the other hand the latter presented a slight over estimation in the depth of such horizon. On the contrary the other two methods showed great precision in the location of the petrocalcic horizon, consistent with the controls made in the field. The errors in the process of inversion were between 12 and 20% for dipolo-dipolo and below 3.5% for the other two arrangements.

Keywords : Geophysics; Soil physical properties.

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