The evolution of the Po river near Trino (Prov. of Vercelli - Piedmont, NW Italy) from the Bronze Age to the XVIIth Century

Abstract

The study of the morphological features and sediments of the Po river bed and its banks, allowed the identification of several phases of erosion and deposition beginning from a period prior to the Middle Bronze Age. Radiometric datings of wooden poles found in the river bed give an indication of the fluvial evolution from the XIII century up to the present. A phase of stability of the river bed, inferred from geological proxy-data, seems to be typical of the period prior to the XIII century, and of the time interval including the XIII-XIV centuries and part of the XV century. During the same period, historical data report a limited number of flood events. There is a correlation between the sedimentation phases begun in the XV century which lasted until at least, the XVII century, and a period characterized by many huge floods, causing great changes in the riverbed. The depositional phase which started in the XV century was probably caused by the climatic changes that produced the so-called Little Ice Age. This period, characterized by a fresh and humid climate, lasted until the second half of the XIX century. During the XIII-XIV centuries phase, which represents the late part of the so-called "Medieval Climatic Optimum" and its phases of transition towards the Little Ice Age, no major depositional processes, nor erosion episode occurred.