Distribution, Discharge, Geological and Physical–Chemical Features of the Springs in the Turin Province (Piedmont, NW Italy)

Abstract

Numerous exploited springs (1571) have been investigated in the Turin Province. They have been mapped with a GIS on a new, specially drafted, geolithological map and statistically examined with regard to areal distribution, discharge, use and lithological composition of their catchment basin. One spring every 4 km² occurs in this area. In detail, the spring density is greater in the mountains (1 spring every nearly 3 km²) than in the plains and in the hills (1 spring every 10–53 km²). These springs are well-distributed in the different altitude ranges, with two peaks at 800–1,100 m and at 140–300 m. They are mostly used for drinking water supply (65 %), irrigation (23.5 %), sanitary use (6 %) and, subordinately (5.5 %), industries, fish farms, production of electric energy and unknown use. The 54.7 % of the springs has discharge lower or equal to 1 l/s, while only the 2.7 % (43 springs) has discharge greater than 10 l/s. A 81 l/day drinking water supply each inhabitant is estimated per capita. The spring areal distribution into the different geolithological units and their discharge values (linked to the aquifer typology) are synthetized. A sample of 28 analyzed springs has bicarbonate to sulfate alkaline-earth facies. Their electric conductivity (100–400 μS/cm) is due to content of bicarbonates (mean value of 100 mg/l) and sulfates (mean value of 15 mg/l). In a single basin (Dora Riparia) the Total Hardness exceeds 25 French Degrees.