Water storage mapping of pyroclastic covers through electrical resistivity measurements

Abstract

The knowledge of the geological setting of pyroclastic covers and their water content distribution represents crucial information for stability analyses of slopes potentially subject to debris-flow phenomena. The study we here present would provide a contribution to this issue by means of an approach based on electrical resistivity measurements. Specifically, we describe the results of high-resolution 2D resistivity surveys carried out in a test area on Sarno Mountains (Campania Region – Southern Italy), where shallow landslides involving pyroclastic soils periodically occur triggered by critical rainfall events. We discuss the results in relation to the geology of the area in order to locate characteristic horizons of pyroclastic soils below the ground surface. Then, on the basis of a laboratory characterization of pyroclastic samples collected from the same test area at representative depths, we provide an estimation of the soil water content distribution in the field. Finally, we analyze temporal variations of the soil water content distribution by comparing the data of two surveys carried out in the autumnal and spring seasons , respectively. ► Water is the main driver of pyroclastic debris-flow phenomena. ► We examine changes of soil water content in the field using electrical resistivity tomography. ► Empirical relationships between soil resistivity and effective saturation are found. ► Geoelectric monitoring can identify the thickness of pyroclastic layers in saturated condition.