River bed changing in the Lower Potenza Valley (Mid-Adriatic Italy). A geo-archaeological approach to historical documents,

This paper presents the results of an integrated survey project aiming to achieve the diachronic reconstruction of changes in river beds during historical times in the Potenza Valley, in mid-Adriatic Italy. Here intensive surveys are being carried out by a team from Ghent University (dir. F. Vermeulen), especially in and around the Roman colony of Potentia, at the mouth of the river. They are aimed at studying occupation history and the relationship man-landscape in this valley between the Apennines and the Adriatic Sea. Interdisciplinary approaches include low altitude aerial photography, systematic archaeological field walking, artefact studies, re-study of excavated evidence, detailed geomorphologic field mapping, geophysical surveys and fine topographic mapping. Thanks especially to active oblique and vertical aerial photography, geomorphologic fieldwork and corings it is now possible to reconstruct a complete frame of the important changes that have affected the river bed during the last two millennia. The archaeological evidence concurs explicitly with the environmental data to understand and determine the general timing of this evolution, allowing us to measure the interaction between mankind and environment through time. Newly found archive documents can now contribute to shed light on the exact chronology of the river bed shifts, giving details on the events of the last centuries, when human interference was much more consistent. These documents belong to the wide family of pre-geodetic maps (such as the so called "cabrei") and the first cadastres (19th century). The georeferenciation of these cadastre maps (including those from the well-known 19th century "Catasto Gregoriano") in the GIS of the Potenza Valley Survey-project offers now the possibility to date several palaeo-channels detected among the aerial imagery and with the help of intensive and integrated geomorphologic survey.