Flood history in the karst environment of Castellana-Grotte (Apulia, southern Italy)

Karst environments are characterized by peculiar hydrologic features, and in particular by a very limited, if not absent, surface hydrography. Water tends to infiltrate rapidly underground through the complex network of fractures and karstic conduits in the rock mass. However, on the occasion of concentrated rainfall, as well as in case of prolonged precipitation, such network might not be able to allow flowing of large amounts of water, which causes the occurrence of floods. This contribution illustrates the flood history in a classical karst area of Southern Italy, the town of Castellana-Grotte, in Apulia. The oldest part of the town lies at the bottom of a karst valley, which was hit by many flood events in the last centuries. More than twenty of these are here documented, starting from critical analysis of existing publications and documents, integrated with additional historical researches. Aimed at reconstructing the flood history at Castellana-Grotte, the best-documented events are described, together with the main factors, which played a role in distribution and gravity of the related damage. Eventually, some engineering works realized during the first decades of the last century, in order to avoid further damage on the occasion of catastrophic floods, are also described.