Tracer tests history in the Alburni Massif (Southern Italy).

The Alburni Massif (Campania, southern Italy) is among the most important Italian karst areas, due to high number of caves (about 300), with several karst systems reaching depth of 500 m, and development of some kilometres. This remarkable karst is mainly related to three geological factors: presence of highly karstifiable and low-fractured Cretaceous and Tertiary limestones; peculiar morphological and structural conformation, with four main faults bounding the massif, forming a wide highplain with a variety of infiltration sites; presence of blind valleys and small catchments on flysch deposits, feeding the many swallets at the contact with the limestone rocks. The Alburni Massif represents an important hydrogeological structure, with a potential of about 10 mc/sec. Three basal spring systems are the main outcomes (Castelcivita, Tanagro and Pertosa) while other minor systems are located at higher elevation, as the Auso spring. The Castelcivita and Pertosa caves, located on the Alburni SW and NE foothills, respectively, are of particular importance also for the local economy, since Castelcivita became a show cave in 1930, followed two years later by Pertosa. Since 1950 many cavers have explored the Alburni Massif, due to the high potential of overall karstification, estimated in about 1 300m, and to the presence on its southern slope of the spectacular Auso spring. In this paper, the tracer tests carried out in the Massif are summarized, with the aim to update the available hydrogeological data, with particular regard to the most recent explorations and tests, carried out during the last 5 years, which brought significant new data to the overall knowledge of this remarkable karst area.