Intrinsic Vulnerability Assessment of a Confined Carbonatic Aquifer: the Brindisi Plain Case (Southern Italy)

Apulia, in the absence of surface water, is one of the Italian regions which satisfy their water requirements by drawing large quantities (over 40%) of its water from underground resources. The large amounts drawn from these resources in the last few years due to increasing human activity on the territory has determined a general and inevitable reduction of the quality of the underground water resources although they circulate in hydrogeological and geostructural environments characterised by a low intrinsic vulnerability. This is particularly true in the Brindisi Plain: a large portion of territory between the Serre Salentine and the Adriatic Sea. The area examined is characterised by the existence of two distinct hydrogeological environments one overlying the other; in the underlying one, made up of Mesozoic carbonate deposits, there is a groundwater body of significant size which satisfies about 30% of the requirements; in the one overlying this, made up of Quaternary calcarenite-sandy deposits, there is a groundwater body of reasonable local importance. For each aquifer, the study evaluated the intrinsic vulnerability using a parametric model, SINTACS, standardised for Italy and modified by the authors in order to adapt it to the particular characteristics of the examined zone. The information obtained in this way was then compared with the quality of the waters circulating in these aquifers. The investigations showed the generally good quality of the waters circulating in the carbonate aquifer and the presence of pollution by nitrates in the vicinity of some wells. By analysing the maps drawn up and from the information collected in situ, it was possible to ascertain that widespread forms of underground water pollution can be blamed on the poor execution of drilled wells and on the lack of suitable management criteria of the groundwater bodies.