Water supply and environmental problems in river headwaters: the case of the source area of the Tiber River (Central Italy)

This work reports the results of a study of Mount Fumaiolo (1407 m a.s.l.). This hydrogeological system, covering an area of about 11 km2, is the source area of the Tiber, Savio and Marecchia rivers (Fig. 1). The basin of the Tiber, ca. 17340 km2, is the second largest river basin in Italy, while its average yearly discharge (ca. 240 m3/s) is the third largest. Due to the Tiber river’s highly irregular hydrological regimen, its basin is subject to frequent droughts and floods, and the Tiber constitute a real flooding hazard for the city of Rome. For these reasons the Tiber has been much studied, focusing on floods, droughts and large groundwater systems. As far as we know, there are no recent studies focusing on the hydrogeological setup of the river source area, characterized by many small springs, among which the larger are connected to drinking water aqueducts. These springs, often not shown on official maps, feed small watercourses which, during dry periods, maintain particular habitats for amphibians. The springs are fed by small, perched aquifers, whose discharge is quite sensitive to climatic conditions: due to prolonged drought periods that have occurred in the central-northern Apennines in recent decades and to the exploitation of the main springs, the habitat of these amphibians is in danger, and their survival is endangered. The Mount Fumaiolo plateau is a well defined hydrogeological unit, resting on very low permeability rocks. Thus, the points where groundwater flows out of the system are known, and the plateau is potentially very suitable for studies about continuous water balances. In this framework, the preliminary results here presented seem to be of some importance, also considering the ongoing climatic change.