From hydro-meteorological thresholds towards an operational warning model for landslides at regional scale: A real-case application

Landslide prediction is essential for developing a landslide early warning system. Recently, hydro-meteorological thresholds combining rainfall and hydrological variables have demonstrated their effectiveness in enhancing the predictive capability of landslide occurrences. However, most territorial landslide early warning systems operational worldwide are primarily developed using only rainfall thresholds, totally neglecting the hydrological process that contributes to landslide initiation. In this study, we propose a three-step procedure aimed at developing a hydro-meteorological warning model intended for operational use employing multiple hydrometeorological thresholds derived from a probabilistic analysis, using soil saturation and precipitation data retrieved from the ERA5-Land product. The model developed herein was tested in one of the warning zones defined by civil protection for the management of geo-hydrological risk in Campania region, Italy. Performance indicators derived adopting the "event, duration matrix, performance" (EDuMaP) method highlight that the hydro-meteorological warning model developed in this study-using real-time forecasts from the Integrated Forecasting System - High-Resolution (IFS-HRES) product-outperforms the current implemented warning model, which depends exclusively on precipitation forecasts. Specifically, the inclusion of soil saturation into the warning model leads to a significant reduction of false alarms. The results achieved herein demonstrate that hydro-meteorological thresholds can be effectively employed within landslide early warning systems for realworld applications at regional scale.