During 25 October 2011, an extremely intense rainfall event occurred in Eastern Liguria and Northern Tuscany. Severe damages were registered in the Monterosso and Vernazza basins, located in the famous area of Cinque Terre, which have been affected by hundreds of landslides, mud flows, and erosions. The main feature of the Cinque Terre landscape is the presence of terraced cultivations on steep slopes facing the sea. The area represents a remarkable cultural landscape, is a National Park, and is included in the World Heritage List of the UNESCO. This work aims to analyze the effect of abandoned terraced land on hydrogeological risks and in landslide prevention, by comparing what happened in Cinque Terre to other experiences presented in scientific literature. The cessation of maintenance of dry stone terraces due to the crisis of traditional agriculture was identified as the main cause of failure during the heavy rainfall event. However, we found some contrasting and, in some cases, unexpected results in the literature regarding the effects of the vegetation that develops on abandoned terraces. This paper compares different results in order to better understand what the future of terraced landscapes is and which are the best management strategies for such complex and fragile territories. In particular, where they represent a cultural heritage and a resource for the rural economy.

Agricultural terraces are an important element of the Italian landscape. However, abandonment of agricultural areas and increase in the frequency of destructive rainfall events has made it mandatory to increase conservation efforts of terraces to reduce hydrological risks. This requires the development of new approaches capable of identifying and mapping failed or prone-to-fail terraces over large areas. The present work focuses on the development of a more cost-effective alternative, to help public administrators and private land owners to identify fragile areas that may be subject to failure due to the abandonment of terracing systems. We developed a simple field protocol to acquire quantitative measurements of the degree of damage—dry stone wall deformation—and establish a damage classification system. This new methodology is tested at two different sites in Tuscany, central Italy. The processing is based on existing DTMs derived from Airborne Laser Scanner (ALS) data and open source software. The main GIS modules adopted are flow accumulation and water discharge, processed with GRASS GIS. Results show that the damage degree and terrace wall deformation are correlated with flow accumulation even if other factors other than those analyzed can contribute to influence the instability of dry stone walls. These tools are useful for local land management and conservation efforts.

The Journal of Agricultural Engineering is the official journal of the Italian Society of Agricultural Engineering - AIIA