Spatio-temporal variability of landslides as indicator of climate change impact: Towards an Italian national scale integrated procedure for the rainfall role analysis in landslide dynamics

Ground instabilities such as landslides, subsidence, sinkholes, and soil liquefaction are highly sensitive to climate change. In Italy, these phenomena represent a major component of hydrogeological risk, particularly in mountainous and hilly regions where recent extreme events have highlighted the growing influence of climatic stressors on slope instability. Intense and prolonged rainfall act both as a preparatory factor, gradually weakening slopes, and as a triggering factor, directly inducing failures. Despite the increasing frequency and severity of rainfall extremes, a comprehensive conceptual framework integrating extreme precipitation behaviour into landslide dynamics is still lacking. This work reviews current knowledge on rainfall induced landslide processes, with specific attention to the distinction between preparatory and triggering mechanisms and to their sensitivity to evolving climatic conditions. Focusing on shallow landslides, where rainfall exerts a more direct and immediate influence than in deep seated processes, we analyse the spatio-temporal variability of landslide occurrence as an indicator of climate change impacts. Building on this review, we develop a national scale conceptual framework composed of standardized toolchains designed to assess and systematically integrate the role of rainfall in landslide dynamics. The toolchains are evaluated through virtual test beds, which provide a controlled yet geomorphologically realistic environment for exploring multi hazard interactions and assessing the internal coherence of modelling workflows. This conceptual validation highlights both the potential and the limitations of existing approaches, particularly the difficulty of translating rainfall information into soil moisture and pore pressure conditions -an essential but still critical step for reliably modelling preparatory processes.