An interdisciplinary approach to the Arno palaeochannels reconstruction since the X century BC in the Pisa coastal plain (Tuscany, Italy)

We have used a interidisciplinary approach involving archaeology, geomorphology, stratigraphy, sedimentology, chronology, history sources and archaeogeography to infer paleochannels evolution of the Arno River. The traces of a centuriation (a method of land division and assignment used by the Romans), are still identifiable in the plain and constitute an important benchmark that helps to recognize the phases of channel migration across the centuries. A wide shallow subsurface data set mainly coming from MAPPA project (www.mappaproject.org), has been used as reference for stratigraphic correlations. The target of the research looks at the upper 8-10 m of the subsurface succession that dates back to the Iron Age. Two new cores, 9 m long, were drilled and sampled using a percussion drilling technique (Vibracorer Atlas Copco, Cobra model), which supplied smaller diameter cores, qualitatively comparable to standard cores. The description of cores lithofacies includes mean grain size, colour, sedimentary structures and accessory materials (shells and fragments; peat horizons or decomposed organic-rich layers; plant debris; wood fragments and calcareous nodules). Facies analyses, archaeological data, and historical sources, have allowed: i) the identification of a paleo-Arno river branch, likely Roman in age, which flowed southernmost with respect to the present-day course and ii) the evidence of significant processes of meanders migration. Moreover, this data opens up new prospects regarding the relationship between the evolution of the Arno River, in the coastal plain area, and the centuriation created by the romans.