Calibration of TDRs and heat dissipation probes in pyroclastic soils

In situ monitoring of the hydrological response probably represents the most effective approach for implementing early warning systems for landslides in pyroclastic covers. To this aim, the chosen devices have to be both reliable and robust, requiring minimal efforts for their maintenance. Among others, two sensors meet such requirements: TDR and heat dissipation probes, used to measure, respectively, volumetric water content and matric suction. Their utilization on large scale is however partially affected by requiring articulated calibration procedures. They have to be provided for each soil type in TDRs and for each probe in dissipation probes. In this paper, for both measurement techniques, the advantages and disadvantages of their use, the procedures developed for their calibration, the evolutions obtained in the subsequent three years of validation of calibration relationships are discussed. Finally, the comparison of the obtained results with those available in the literature for in situ monitoring systems is shown. are shown for in situ monitoring systems. (C) 2014 Elsevier B.V.