Integrated soil erosion and mass movement assessment using LISEM in the Vernazza catchment, Liguria, Italy

A disastrous flash flood in the Vernazza catchment, Cinque Terre, Liguria, Italy on the 25th of October 2011 with numerous landslides and severe soil erosion caused fatalities and economic losses amounting to millions of Euros. The area is characterized by a terraced landscape and steep slopes. Most of the terraces are abandoned and used for vine and olive production in former times. The related processes are triggering each other and lead to degradation of the slopes and particularly affect abandoned terraced areas. To study the dynamics and potentially affected areas in terms of source, transport, and deposition of sediments we applied the Limburg Soil Erosion Model (LISEM). LISEM is based on detailed soil, topography and landuse information. We applied the model on a 1m scale using climatic data from two nearby weather stations and detailed soil geotechnical properties collected from the field. LISEM assessed the hydrological dynamics and related processes linked to surface runoff such as soil erosion processes as well as landslides related to the soil water content. The results show the spatial distribution of soil erosion processes and landslides. Moreover, we characterise the sediment transport pathways and depositional zones. The results help to identify critical areas needing interventions and particularly to recognize the abandoned terraces prone to collapsing. Hence, our LISEM approach yield valuable information for basin managers, farmers and environmental protection agencies.