Towards a global approach to scan earthen levees

The recent occurrence of floods in Northern and Central Italy as well as in the entire Europe caused important damages to agriculture, industry and infrastructures, to residential buildings and in some cases were also reported several casualties. Among these the November 2010 event, mostly occurred in the plain area of the Veneto Region (North-Eastern Italy), was particularly severe reaching a maximum rainfall intensity of more than 200 mm in 10 hours and causing the failure of 15 river embankments. The structure and the stratigraphy of earthen levees and of their geological basement represent a vital information and the eventuality of a collapse, also of minor embankments, frequently involves unaffordable social cost. The standard approach of monitoring the levees using sparse geotechnical tests and visual analysis is no longer satisfactory as the recent changes in the flood regime increased the stress on these structures and the associated risk of failures. An high resolution geophysical imaging procedure (namely EMAR), based on electromagnetic induction (FDEM) and multichannel radar (GPR), has been developed, tested and validated on a large scale survey of the embankments of a major river in North-eastern Italy. Using this procedure it was possible to investigate more than 100 km of embankments in 5 working days showing great potentials to cost-effectively monitoring earthen levees.