LONG-TERM TRACING IN KARSTIC AQUIFER RESERVOIR FOR DRINKING WATER: THE EXAMPLE OF CHAIN PEAKS OF THE MUSI MOUNTAIN' (WESTERN JULIAN FORE-ALPS)

摘要

The chain of the Musi mountain (1869.4 m) is one of the most important karst massifs of the Western Julian Fore-Alps (Italy). On the northern slope the Barman spring is located, on the southern slope the Voidizza springs and the Torre springs are located. Almost the whole feeding basin of the above-mentioned springs is placed in a protected area managed by 'Ente Parco Naturale delle Prealpi Giulie'. Therefore, the zone is an important example of an area having high vulnerability due to karst and it is strategic for the water supply for an important part of Friuli. Two tracing tests were carried out injecting Uranine into the Pahor abyss on the northern slope. From these tests it results that the waters of the karst area drain in the Uragano cave and in the underlying Barman spring. Only during heavy low water, when the underground watershed of the massif lowers, is it possible to observe traces of Uranine in the Torre springs, since the most northern underground regions of the massif are drained. The tracer test was supported by a chem icophysical study of the underground waters of the massif, and analysis of the stable isotopes (δ~(18)O, δD) was carried out.