Protezione idrogeologica di sorgenti in acquiferi fratturati non carsici

The paper deals about the mapping of contribution and well-head protection areas for springs discharging out from non karstic fractured aquifers. In the specifi c case we refer to mainly sedimentary hard rock aquifers occurring in Northern Apennines (Italy): they are represented by turbidites and arenites, and by ophiolites at a lower extent, characterized by high heterogeneity and anisotropy in the hydraulic conductivity distribution. Groundwater fl ow numerical modeling, by the adoption of Equivalent Porous Medium (EPM) approach, is presented as the most suited and robust tool in order to locate, according to a physically based approach, contribution and protection areas of springs; the main mandatory prerequisites are the availability of a reliable geological model derived from a detailed geological survey of the area and the occurrence of multi-year time series of continuous monitoring of spring discharge. The presented case study is about a main public water supply spring and, at the same time, a Groundwater Dependent Ecosystems (GDE) of paramount importance in the area. The application is preceded by a review of different methodologies employed to map non karstic spring contribution and protection areas, updated with recent references. The recharge area derived by numerical modeling has an extension of about 2.40 km2, this area produces an average spring fl ow rate of 12.43 l/s. Spring protection areas were defi ned by the envelop of the 60 days and 365 days travel times. Their extensions are, respectively, 1.6% and 11.4% of the recharge area. Finally, the infi ltration coeffi cient, above the contribution area, resulted equal to 17%. At the end of the article a hybrid methodology to map contribution and protection areas of springs in a mountainous non karstic setting is proposed.