Computers & Geosciences, Published Online 17 May 2014

By Davide Tiranti, Roberto Cremonini, Federica Marco, Armando Riccardo Gaeta, and Secondo Barbero

“Highlights:

• A software tool for debris flows forecasting in Alpine environment are described.
• The warning tool merges a new basin classification and the storm tracking by radar.
• The observed/nowcasted rainfall can be compared with a thresholds system.
• The approach is oriented to real-time analysis and nowcasting-derived products.
• Real-time application of GIS tools to predict severe storm ground effects.

“Debris flows, responsible for economic losses and occasionally casualties in the alpine region, are mainly triggered by heavy rains characterized by hourly peaks of varying intensity, depending on the features of the basin under consideration. By integrating a recent classification of alpine basins with the radar storm tracking method, an innovative early warning system called DEFENSE (DEbris Flows triggEred by storms – Nowcasting SystEm) was developed using a Geographical Information System (GIS).

Example of storm tracking and nowcasting. Storm UTC time is shown in the centre of the cells, while colours identify storm severity and the cone represents the forecasted path.

“Alpine catchments were classified into three main classes based on the weathering capacity of the bedrock into clay or clay-like minerals, the amount of which, in unconsolidated material, directly influences the debris flow rheology, and thus the sedimentary processes, the alluvial fan architecture, as well as the triggering frequency and seasonal occurrence probability of debris flows. Storms were identified and tracked by processing weather radar observations; subsequently, rainfall intensities and storm severity were estimated over each classified basin. Due to rainfall threshold values determined for each basin class, based on statistical analysis of historical records, an automatic corresponding warning could be issued to municipalities.”

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