Preliminary results of vulnerability assessment of the karst aquifer feeding pertuso spring, in central Italy

Vulnerability assessment of the aquifers is an important tool for the groundwater management and protection. This paper aims to assess the intrinsic vulnerability of the karst aquifer feeding Pertuso spring, which is going to be exploited to supply an important water network of the South part of Rome. The study area is located in the Upper Valley of Aniene river and belongs to an important karst aquifer, mainly composed of dolomitic limestones and dolomites of Cretaceous age. The limestones outcropping in the Upper Valley of Aniene river are deeply fractured and karst erosion has occurred on a large scale in this area. The surface karst activity led to the formation of a typical karst landscape. The hydrogeological framework is therefore closely related to the karst nature of carbonate rocks, constituting the reliefs strongly shaped by surface and underground karst activities. The peculiar fragility of this aquifer, feeding Pertuso spring, requires a special attention to protect catchment area, which is directly affected by the natural hydrogeological budget of the aquifer. Therefore, for the evaluation of vulnerability index and maps COP method was applied considering overlying layers (O), concentration of flow (C) and precipitation regime (P) parameters. The vulnerability of the karst aquifer is classified mainly as moderate, high and very high due to the presence of cemented conglomerates, compact dolomitic limestones and granular limestones, respectively. COP method shows that each factor has a different effect on vulnerability index evaluation, however the highest correlation was observed with O factor due to the absence of soil formations. The results obtained by COP method assess the aquifer vulnerability to contamination and are useful for managing the protection of groundwater resources, especially to avoid contamination of karstic aquifers, and land use planning in the area.