The path of water in relation to human communities: history of a middle-age aqueduct in Apulia (southern Italy)

Availability of freshwater has always played a crucial role in the foundation and establishment of human communities. In regions characterized by arid or semi-arid climates, or in karst areas where surface water is typically lacking or very scarce, this has often been a problem, forcing man to look for water through detailed knowledge of the local hydrogeology. From these issues, the realization of hydraulic works, frequently entirely or in part built underground, started in different epochs. In the research here presented, starting from the outcomes of a project dedicated to ancient underground pipelines in Italy, we describe the hydrogeological setting and the historical framework of the “S. Angelo – Fontana della Stella” water supply system, one of the most remarkable evidence in the territory of Gravina in Puglia (Apulia). As documented by historical sources, the construction of the hydraulic work started in 1743. With an overall length of 3,500 meters, the aqueduct is one of the best preserved underground man-made structures for collection and transport of water resources in southern Italy. It starts from an intake located some kilometers north-west from the town, draining waters coming out at the contact between Plio-Pleistocene calcarenites and the overlying clays. A system of underground galleries, connected to the surface by a number of inspection wells, allowed the waters to flow to the town. The subterranean system ends up at the right valleyside of the Gravina Torrent; to pass the deep canyon, and let the water reach the final destination where, a bridge-channel was built across the torrent. As described from the speleological explorations, and the historical researches as well, the “S. Angelo – Fontana della Stella” water supply system is a very important heritage for the entire region, since it represents one of the most significant ancient subterranean water systems in Apulia, also testifying the hydrogeological knowledge reached at the time of its realization