When instrument location makes the difference on rainfall thresholds definition: Lessons learned at Cancia, Dolomites

Since debris flows represent one of the most dangerous natural hazard in mountain areas, Early Warning Systems (EWSs) play a crucial role reducing risk these hazardous processes. Robust event pre-alert usually relies on long time series local rainfall measures. Oftentimes regional rain gauge networks present an insufficient spatial density to grasp highly variable spatio-temporal dynamics debris-flow triggering events and thus relying such for developing thresholds might lead relatively low estimates. The paper reports development operational Cancia EWS, Dolomites (NE Italy). instrumentation configuration led derivation implementation set that significantly enhanced pre-alarm reliability thanks optimal distribution multiple gauges within catchment. Notwithstanding small number occurred during calibration period, were derived considering whole population showcasing statistical properties those initiation. Finally, validation period served as proof work proposed with no raised false alarms identification few minor, but correctly detected, flows.