Caratteristiche geomorfologiche ed evoluzione recente della piana del T. Polcevera: Rapporti con gli interventi antropici

Abstract

The terminal portion of the Polcevera valley, one of the widest coastal plains in central Liguria, is the main urban and industrial area in the western part of the city of Genoa. An attempt has been made to reconstruct the possible evolution of the area during Quaternary and Holocene times, on the basis of a large-scale geomorphological survey. The survey takes into consideration residual marine and fluvial surfaces. The reconstruction is also based on a great number of stratigraphic data, obtained from direct and indirect investigations and palseobotanical analyses in the plain and along the coastal area, currently under construction. The impact on environment dependent upon the increansingly intensive anthropization of the area has been analysed from a historical and present-day point of view. Over the past 150 years urban and industrial settlements, road, railways, new basins and port facilities initially involved the coastal plain; in more recent decades this has extended also to the hilly region. The above-mentioned infrastructures caused a progressive search of a new coastal outlet, with the construction of big embankments and protective walls, completely transforming the littoral landscape. Such changes brought about the disappearance of 3.6 km of beach and the reduction of the bed width in the terminal stretch of the Torrente Polcevera, from 450 m to less than 100 m. Large discharges have been located along the shoreline in front of Cornigliano and Sampierdarena, exploited for touristic purposes up to the first decade of this century. Such new artificial new areas have caused the displacement of millions of cubic metres of detritus pushed to the bathymetric line of 15/20 m. Consequently the coastline has advanced by 700/1000 m. The interference between anthropic morphogenesis and natural geomorphological conditions has given rise to new environmental features, which are often near and sometime even beyond the endurance capacity of the territory, with increasing natural and industrial hazards. Nowadays there are many possibilities for the re-utilisation of abandoned or semi-abandoned areas, at present occupied by siderurgical installations and by petroleum warehouse.