A Monitoring System for Time-lapse Electrical Resistivity Tomography (ERT) and Time Domain Reflectometry (TDR) Measurements

A permanent monitoring system for time–lapse acquisition of 2D Electrical Resistivity Tomography (ERT) and Time Domain Reflectometry (TDR) measurements was installed in a test site affected by a landslide in Basilicata region (southern Italy). Time-lapse acquisition allows us to monitor in real time the variation of resistivity values in the first layers of the subsoil, closely connected with variation of the water content and potentially associated to the reactivation of the landslide. A weather station installed in the test site gives information about the rainfall intensity and frequency and suggests the acquisition time interval. Resistivity trend analysis was carried out in different ways: at first acquiring many sets of data that were inverted by the software RES2DINV, in order to obtain a series of ERT representative of the resistivity distribution in the subsoil during different periods of the year; then, considering resistivity data coupled with TDR ones and rainfall, realizing a statistical study in the time and space. Statistical study has been made by using a MATLAB script specifically created for this work. The installed system and the results are presented.