Distribution, discharge, geological and physical-chemical features of the springs in the Turin Province (Piedmont, NW Italy)

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 ??S/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.