Landslide susceptibility map in the green peri-urban context of Rome

The correlation between the absent of forests and the occurrence of landslides is well-know. In fact, the forests provide a protection in the soil degradation and erosion through the trees presence and roots contribution. In shallow terrains, soil cohesion is enhanced by roots while the trees modify the soil moisture through increased evapotranspiration. In addition, in deep soils, the roots create macropores with hydrological drainage networks. However, extreme rainfall can be trigging the soil movement because soil moisture is inversely related to soil cohesion and plasticity. For this reason, identify areas susceptible to landslides is fundamental for territory management especially for the damage they could cause in urban and rural areas. In the light of this, we propose a GIS (Geographic Information System) approach to obtain risk maps for the assessment of landslide susceptibility based on the Shallow Landslides Stability Index (SLSI) model. The SLSI model considering the effect of root cohesion and it based upon the infinite slope stability model. This method was applied in a peri- urban context of Rome, in the green area of Monte Mario, for determining the Landslide susceptibility map. The map shows that close to 27% of the area has a high susceptibility to mass movements, 32% presents medium susceptibility and 41% a low threat. This area is valuated to high hydrogeological risk by the basin authority of the Tiber (Hydrogeological Structure Plan - PAI).