Historical Geomorphological Research of a Ligurian Coastal Floodplain (Italy) and Its Value for Management of Flood Risk and Environmental Sustainability

Abstract

The alluvial plain of the Entella River (Eastern Liguria), historically affected by damaging flood events, has been heavily modified over the past 250 years by human activity and natural processes. A qualitative and quantitative analysis of the morphological and land use evolution of the Entella floodplain since the 18th century was carried out using base maps and aerial photos ranging from 1758 to 2016. These diverse sources were Geographical Information System (GIS) georeferenced. Additional information on land-use change was gathered from historical documents and recent research reports. The main transformations to the floodplain include morphological changes, e.g., narrowing, channelization, displacement of the river channel and the advance of the coastal line due to fills and embankments. In addition, there has been very significant urbanization with loss of vegetated and agricultural areas. Our results indicate the primary role of human disturbance on morphological changes and landscape modifications of the coastal floodplain, particularly over the last 200 years. Furthermore, the historical geomorphological and cartographical analysis we adopted to reconstruct the floodplain transformation represents an essential tool in flood risk mitigation and environmental sustainability management, particularly in an urbanized coastal plain historically affected by floods.

Geomorphological Landscape Research and Flood Management in a Heavily Modified Tyrrhenian Catchment

“…This is very evident in the north-western Italian region of Liguria, which has been affected by a significant number of flood events in recent years and it is characterised by widespread geo-hydrological phenomena. Previous research focused on coastal areas, looking at the way in which geomorphic processes due to human interference increased geo-hydrological hazard [25][26][27][28]. Other studies concerned mountain contexts either in the Po Valley catchment, often independent from human interaction [29] and coastal catchments characterised by landscape changes and anthropogenic landforms [30].…”

Large-scale geomorphology of the Entella River floodplain (Italy) for coastal urban areas management

“…The plain is urbanized and occupied by the cities of Chiavari, Lavagna and Cogorno, for a total of about 50,000 inhabitants. Most of these urban areas are long-standing settlements built on ancient prehistoric villages, which gradually developed during the Middle Ages and underwent to rapid urban sprawl due to the socio-economic growths afterwards the industrial revolution, in the nineteenth century, and the World Wars, in the 1930s and 1960s (Del Soldato, 1987Ragazzi & Corallo, 1981;Roccati, Faccini, Luino, Turconi, Piana, et al, 2018). In particular, the floodplain of Chiavari and Lavagna suffered a massive anthropogenic transformation since the latter half of the nineteenth century.…”

“…In particular, the floodplain of Chiavari and Lavagna suffered a massive anthropogenic transformation since the latter half of the nineteenth century. Human interference heavily altered the former landscape and the hydrographical network (Roccati, Faccini, Luino, Turconi, Piana, et al, 2018).…”

Structure-from-Motion (SFM) Photogrammetry as a Non-Invasive Methodology to Digitalize Historical Documents: A Highly Flexible and Low-Cost Approach?

“…Historical documents represent an important source of information about our past as well as an invaluable component of our cultural heritage. In particular, in recent years historical cartography has increasingly become a useful source for many research fields such as geomorphology [1,2], geoarchaeology [3,4] and geoheritage [5] to understand the human-induced modification on the landscape through time. Ageing is the main problem for the conservation of fragile material used to create this kind of geographic datasets.…”