Hydrogeological framework of minor aquifers in Central Italy (Alto Sangro area) and potentialities' assessment for drinking purposes

Drinking-water supply in high altitude villages in central Apennines is ensured by springs with a limited and seasonal discharge. These allow villages self-sufficiency with some summer deficit in water availability because they can not take advantage from lower elevations’ springs which are used for coastal areas supply. In the Alto Sangro area, that includes the south-eastern portion of the Abruzzo region’s mountain area and the north-western part of Molise region, many springs located at altitude higher than 1000 m are tapped for drinking purpose. However, their use is still limited because of the managing companies’ exploitation and distribution strategies; in fact, investing in springs or well fields with major potentials is preferred, even if a more energetically demanding for water distribution is required. In this work, features, potential and residual capabilities of these aquifers have been highlighted and described. The structural set-up is peculiar: tectonic relationships between formations occur mainly through faults and low angle thrusts, which put in contact terrigenous lithologies with different permeability, within the so-called "coltre molisana", and with the mainly carbonatic succession of the central Apennines and the Sicilidi calcareous-clayey. The complex stratigraphic and tectonic relations between these formations allow groundwater to emerge as springs, which are mainly classified as “for permeability limit” (Civita, 1973). The coltre molisana’s calcarenites or the Apennines limestone formations usually represent the calcareous hydrogeological complex, while the aquiclude correspond to the clayey complex of the Sicilidi or the coltre molisana’s clay. Sometimes, the coarse slope deposits serve as aquifers, too: they come from carbonate deposits located at higher altitude, and lie over impervious complex. The first results about groundwater potentialities of these high-altitude springs, have been obtained through infiltration coefficient and it shows recharge volumes of about 100 Mm3, over a 615 Km2-wide area; this can be coupled with numerical modeling, using MODFLOW with Model Muse interface, for a more accurate quantification.