DARFLIS-Distributed quantitative risk Analysis for Rapid Flow-like Landslides induced by high Intensity Storms

The mountainous areas of the Lombardia region (Italy) are characterized by a heavily landslide-prone topography, as mountain and hilly territories represent more than 50% of the total area. Rapid flowlike landslides, defined in the scientific literature as flow slides, fast soil movements and debris flows are the most frequent types of landslides occurring in such region (about 41%). These landslides are triggered by heavy rainfall and water plays an important role both in the triggering and the propagation phase. As well known, these landslides are particularly destructive events. This is due to the fragile response of the material when the process initiates, to the limited or no premonitory signs, and to the enormous potential damage associated with i) the large volumes of mobilized soil, ii) the high velocity reached by the fluidized materials and iii) the long travelling distances. These events can cause serious social, environmental and economic consequences, and can be found with similar features in numerous regions of the world, such as Eastern United States, South-East Asia, and South-America. Despite the significant progress made in the last two decades in the understanding of the triggering processes and of the hydro-mechanics of free surface gravitational flows of granular materials, numerous knowledge gaps still exist in i) the quantitative evaluation of the hazard and risk assessment associated with this kind of natural phenomena, ii) the reduction of the mitigation costs. The aim of the project is to improve the current state of knowledge of the areas at risk and to develop a reliable strategy for quantitative hazard assessment of rainfall-induced flow slides and debris flows. In particular, the project will provide a methodological path to define the potential unstable volumes, the propagation distance, and the possible interaction with existing structures and infrastructures. The successful implementation of these goals can represent a major step forward with respect to common rainfall thresholding, as it would allow public agencies to differentiate landslide source areas according to the triggering probability and the expected type of post-failure evolution (e.g., sliding or flowing).