The 1915 Mud-Debris Flow at San Fruttuoso Di Camogli: Modeling the Collapse Effects in the Portofino Pilot Area of the H2020 Reconect Project

In mountainous areas during intese rain events shallow landslides are often triggered adding their effect and enhancing the damaging consequences of flash flood. Many coastal area of the Mediterranean are exposed to such events, as recently largely happened in Italy, France, Spain and Greek. Large portions of the coastline mountainous territories have been settled and modified since ancient times with agricultural terraces, in order to practice the subsitence cultivation. This kind of anthropogenic modification of the slopes may be considered as an artificial immobilization of debris cover along steep slopes and, particularly after their abandonment, they can turn into sources of shallow landslides. Then terraces from belonging to soil and water conservation measures may represent a source of hazard if not properly mainteined. Considering the intense rain event that hit the Portofino promontory in 1915 causing strong damage to the Medieval monk Abbey in the iconic small San Fruttuoso village in northern Italy, a numerical modeling has been applied basing on historical testifying and the available evidences. A possible terraced area has been highlighted as a source area for the debris/mud flow that hit the Abbey and the model has been applied to assess its effect. This reconstruction allows to test the modeling technique in order to furtherly assess possible risk scenario even in other areas and in the framework of the H2020 RECONECT project, where recovering ancient terraces is considered in the framework of the Nature Based Solutions to riduce geo-hydrological risk.

Automated summary

Intense rain events in mountainous areas can trigger shallow landslides, causing additional damage during flash floods. Coastal areas in the Mediterranean are particularly vulnerable to such events. Ancient agricultural terraces, which were commonly practiced for subsistence farming, can become a source of hazard if not properly maintained. In this study, numerical modeling was used to assess the effect of a terraced area on a mud/flow event that occurred in San Fruttuoso village in northern Italy in 1915. The results of this modeling can be applied to assess similar risk scenarios in other areas, particularly in the context of the H2020 RECONECT project that focuses on using nature-based solutions to reduce geo-hydrological risks.