Resilience to climate change: adaptation strategies for the water supply system of Formia and Gaeta (Province of Latina, Central Italy)

The aqueduct serving the municipalities of Formia and Gaeta (Latina province, Italy), an area under the enforcement and control responsibility of “ATO 4” Autorità d'Ambito Territoriale Ottimale – (Integrated Urban Water Management Agency), is supplied by two important karst springs. These springs, fed by the western Aurunci Mountains system are known as Mazzoccolo and Capodacqua having an average flow rates of 1100 l/s and 1300 l/s, respectively. Although these sources have been used since ancient Roman times and the quality of their water is excellent, variations in the precipitation regime, possibly related to worldwide climate changes, has exacerbated the following problems: a decrease in the flow rates of the springs caused by the reduction in winter rainfall, and an increase of turbidity due to concentrated rainfall events. In order to mitigate these problems, which affect a resident population of about 150,000 inhabitants, Acqualatina S.p.A. - the water utility company - promoted a series of geological and hydrogeological surveys. These studies aim at increasing the knowledge on the geological setting and to find additional sources to improve the existing supply. Within the framework of these activities, we studied a strategy aimed at diversifying the water supply by identifying new exploitable aquifers in the area, to reduce the aforementioned problems. This paper presents the results of research carried out before and during the construction of the water well field “25 Ponti” located in the coastal area of the plain of Formia. The research consisted in laboratory analyses of 130 groundwater samples and in monitoring of piezometric trends. The data show a seasonal variation in groundwater chemical composition caused also by aquifer exploitation, which in some periods of the year affects the regulated reserves. This seasonal phenomenon was however present in absence of pumping.