Landscape analysis and Connectivity Index to assess debris flows susceptibility of recently deglaciated catchment (Presanella Group, Rhaetian Alps)

High-altitude Alpine regions are highly sensitive to ongoing climate change, which affects cryosphere dynamics and intensifies slope processes. Since the Last Glacial Maximum, deglaciation has expanded paraglacial environments, increasing susceptibility to mass-wasting processes. Debris flows are particularly frequent and hazardous at higher recently deglaciated elevations but also affect lower catchment areas. We present a debris flow susceptibility map of Valpiana valley (Adamello-Presanella Group, Rhaetian Alps) based on landscape analysis and statistical selection of causal factors. Given the key role of debris flows in sediment transport, we assess connectivity between source areas and downstream sectors. Results indicate a significant rise in debris flow susceptibility from 1983 to 2015, with higher susceptibility classes expanding across 35% of the study area. This increase is pronounced on screes and debris cones, and has substantially intensified on Holocene glacial deposits as well, where 50% of the area belongs to the highest susceptibility class. High-susceptibility zones are increasingly concentrated along debris flow channels and in unconsolidated debris areas, while exposed bedrock sectors show reduced susceptibility. This spatial pattern appears strongly influenced by positive feedback associated with channel evolution following extreme rainfall in 1987, which triggered debris flows in specific areas, and is confirmed by statistical analysis. Among key causal factors, the contributing area remains the primary driver, exerting a growing impact over time. These findings highlight the increasing geomorphic instability of high-altitude Alpine landscapes due to climate-driven changes and emphasize the rising significance of debris flow processes in shaping paraglacial environments.