REFINEMENT OF SEEPAGE VULNERABILITY ESTIMATE IN NATIONAL LEVEE DATABASE OF ITALY

Piping induced by seepage is a frequent cause of failure for earthen levees. The probability that the seepage line in the levee body intercepts the landside slope provides an important indication of the levee vulnerability to seepage. Nevertheless, the definition of the seepage paths associated to assigned water levels is affected by the difficulty in estimating the hydraulic parameters that control the filtration process, chiefly the soil hydraulic conductivity. The ideation of expeditious and operational methods, able to analyse extended levee systems quickly and to identify the most vulnerable portions of the systems, is therefore of paramount importance. To this purpose, an existing practical procedure for the evaluation of levee vulnerability to seepage, based on the definition of a vulnerability index (Camici et al., 2015), is here enhanced and it is used to produce 'synthetic diagrams', easily applicable to derive the seepage probability of the dykes whose hydraulic conductivity is unknown. The procedure is applied for the Tiber River (central Italy) and the Tanaro River (northern Italy). The Italian levee database (DANTE) is briefly presented in the final part of the paper: it is conceived as a dynamic geospatial tool, addressed to collect all the available information on levee systems and to usefully support authorities involved in hydraulic risk mitigation.