RECONSTRUCTION OF RUNOFF DRIVEN DEBRIS FLOW IN THE ITALIAN APLS: A STUDY OF EROSION AND DEPOSITION PATTERNS OF DEBRIS FLOW

Código

IV-END0186

Autores

Leonardo Rodolfo Paul, Gean Paulo Michel, Vittoria Scorpio

Tema

08 - Movimentos de massa

Resumo

Debris flows are high magnitude sediment transport processes that entail deep landscape changes and evolution. Processes of erosion and deposition are widely acknowledged in the investigation of debris flow dynamics, as they impact the natural hazards in mountain areas. As a result, efforts are being made to develop robust models that encompass erosion and entrainment processes into debris flow dynamics. Nevertheless, the capacity of the model to reproduce the patterns of debris flows are seldom evaluated. This study reconstructs 7 debris flow events in the Stolla creek catchment, Italian Alps, triggered in 2017 and assesses the reliability of a physically based model to reproduce the erosion and deposition processes. To calibrate the model and verify the agreement between erosion and deposition areas, a DTM of difference of the topography before and immediately after the event is utilized. First a sensitivity analysis was carried out to identify how the entrainment volume would vary and to check the range in which parameters would still reproduce a verisimilar behavior. Then, the model was calibrated to match the observed total volume and the affected area. The best-fit scenario was selected based on performance metrics and the simulation was evaluated in terms of agreement of deposition and erosion areas. We found that entrainment volume is more sensitive to input parameters than the affected area, and without the entrainment, the volume error increases. The model reached deposition/erosion agreement rate up to 79% and in terms of area agreement, True Positive Ratios ranging from 60% to 90%.