Anthropogenic changes in the alluvial plains of the Tyrrhenian Ligurian basins

Riverbeds and floodplains in the Mediterranean area have been largely affected by anthropogenic modifications mainly with incision, narrowing and channeling of the riverbed. In many cases these changes have also involved the river network, from braided to single thread. The Ligurian coastal floodplains are historically affected by flooding. In recent decades, an increase in floods has been observed either for the variation of the rainfall regime and for man-made landforms that influenced the geomorphological processes. This paper provides a first analysis of the morphological evolution of the ‘floodplain-riverbed’ system in the recent past in Ligurian Tyrrhenian basins. Human activities have modified the environment of the coastal floodplains: in all the analyzed cases the narrowing and the culverting of the riverbed have been found above all in the terminal stretch. Other changes concern diversion of watercourses and progradation of the coastline due to embankment. In many cases, the extent of the changes obliterated the presence of watercourses, reducing or eliminating the perception of risk. The knowledge of anthropic changes should therefore be used as a management and planning tool in the framework of risk reduction activities.