Man-made Terraces: From Ancient Anthropic Landscape Modification to
Value at Risk. The Example of 5 Terre and Portofino, Italy
Abstract
Man-made terraces for agricultural purposes are a quite diffuse and
ancient anthropogenic landscape modification in mountainous areas. The
original slope alteration, obtained through a sequence of sub-vertical
and sub-planar surfaces, represents a human interference with the
geomorphic system, altering the original balance of geomorphological and
geo-hydrological factors. Stone walls and soil formed by human activity
have been artificially immobilized on the slopes and are available again
to gravitative processes once in abandonment and may be subject to deep
degradation in case of intense rain events. However, socio-economic
conditions play often a crucial role in the abandonment of terraces,
indirectly contributing to increase gully erosion and walls failure. The
modification of the original slope profile, due to its regular geometry
in respect to the typical more complex natural surface, is rather
suitable to be detected through remote sensing, particularly LIDAR, as
many authors have recently demonstrated. In the present research the
attention has been focused on the assessment of terraces and of the
volume of stones and soil that have been involved by human activity. The
research area is among the most deeply modified by terraces in the
Mediterranean area and internationally famous for this landscape
anthropogenic alteration: The Cinque Terre in Italy is a National Park
intensively visited by tourists all over the year. Then terraces
represent an important economic asset that need to be preserved from
degradation and collapse as partially occurred in 2011 after the intense
rain event that caused flood, hundreds of landslides and consequently
damage. During the 2011 event many terraced slopes have collapsed with
significant loss of soil and stone walls: the research allowed to
evaluate the lost volumes and to estimate the remaining ones in the
Vernazza catchment.