Regional-scale debris-flow modelization for hazard mapping in alpine basins using a high-resolution DTM and events geodatabase

A very detailed geodatabase of floods, landslides and debris flows is available and kept up to date for the territory of the Autonomous Province of Bolzano, in northeastern Italy (7400 km2). The database is fed by field surveys carried out after the occurrence of instability phenomena and reports locations and attributes of the events for the last 15 years. The on-site analysis grants the gathering of important information and documentation resulting from field measurements and interviews to witnesses of the events. Particular attention is paid to the recognition of location, magnitude and path of landslides and debris flows. Data on shallow landslide locations and debris-flow initiation sites have provided the input to a regional-scale debris flow model aimed at the assessment of debris flow paths and inundation areas. A simple mass propagation model based on topographic attributes (Huggel et al., 2003) has been applied to simulate mass movement phenomena for selected basins using initiation sites listed in the regional database. In the model, debris-flow propagation is given in probability-related values representing the hazard potential for the selected locations. All the simulations have been carried out using a high-resolution (2.5m) LiDAR-derived Digital Terrain Model (DTM). The combination of a georeferenced database of landslides and debris flows and a simple topography-based model constitutes therefore a reliable tool for a fast and preliminary debris-flow hazard estimate, assessment and mapping. References: Huggel C, Kääb A, Haeberli W, Krummenacher B. 2003. Regional-scale GIS-models for assessment of hazards from glacier lake outbursts: Evaluation and application in the Swiss Alps. Natural Hazards and Earth System Sciences 3(6):647-662.