Dendrohydrology is the application to the study of river dynamics, particularly useful for reconstruction and dating of floods in areas without historical documentation. The study is carried on, as in the case of river Magra (fig. 1), analyzing the stresses suffered by trees (fig. 2-3), folded from flooding, the impact scars on the upstream side and plants with new sprout (fig. 4). Within the flood plain areas, coeval vegetation zones gives information on the geomorphological evolution of the watercourse (fig. 5).