GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 3.2 ___ GNGTS 2023 Calibration and comparison of electromagnetic data based on electrical resistivity tomography in levee context O.S. Araújo 1 , F. Bocchia 1 , R.G. Francese 1,2 , M. Rossi ¹ , S. Picotti², M. Giorgi² 1 Università degli Studi di Parma, Parma, Italy 2 National Institute of Oceanography and Applied Geophysics - OGS  Abstract Sand intrusions represent engineering and geological issues for river embankments due to the structural instability provided by the hydraulic flow paths. Proper inspection and evaluation are essential to determine the problem areas in river embankments and repair them before any damage occurs. Geoelectrical surveys are a reliable method used widely and are considered promising for risk mitigation and failure identification. In this context, Electromagnetic Method (EM) is the geophysical method most widely applied as a preliminary zoning on a large scale, while Electrical Resistivity Tomography (ERT) is used for local or detailed surveys. In terms of electrical conductivity values, EM results need some calibration proceedings. Based on ERT data, we performed an Electromagnetic calibration needed to improve the accuracy of procedures in a test area of the Brenta River, located in Campolongo Maggiore (VE). Electromagnetic measurements were carried out using two instruments of low induction number (DUALEM-642S and CMD-Explorer). Results led to mapping sand intrusions, while the correlations and comparisons highlighted the influences of heterogeneities of the ground. Integration of geophysical and geotechnical data allowed the characterization of the inner river embankment structures. Keywords: geoelectric, geotechnics, levee.   1.  INTRODUCTION An embankment or levee can be made of different materials, and various construction methods are used; for this reason, each flood protection embankment is considered unique. These varieties of methods and compositions turn the internal structure of levees into a heterogeneous medium. This represents a challenge for their analysis and the better engineering solution choice related to their vulnerability and instability.