Debris flow run-out simulation and analysis using a dynamic model

Abstract

Abstract.Only two months after a huge wildfire occurred in the upper part of a valley located in Central Portugal, several debris flows were triggered by intense rainfall. The event caused infrastructural and economical damage, although no life was lost. The present research aims to simulate the run-out of two debris flows occurred during the event as well as to calculate by back-analysis the rheological parameters and the excess rain involved. Thus, a dynamic model was used, which 10 integrates surface runoff, concentrated erosion along the channels, propagation and deposition of flow material. The rheological and entrainment parameters obtained for the most accurate simulation were then used to perform three scenarios of debris flows run-out at the basin scale. Due to the lack of quantitative information to validate these models, the results were compared with historical references of debris flow events in the study area. Six streams were identified, where debris flows occurred in the past and caused material damage and loss of lives. The worst-case scenario carried out at the basin 15 scale shows a potential inundation that may affect 345 buildings at the present day.