Avaliação da suscetibilidade à rutura e propagação de fluxos de detritos na bacia hidrográfica do rio Zêzere (Serra Da Estrela, Portugal)

Abstract

In the framework of the landslide susceptibility assessment the maps produced should not only include the landslide initiation areas, but also those potentially affected by the mobilized material. To achieve this purpose the susceptibility analysis must be separated in two distinct components: (i) the first one, which is also the most discussed in the literature, deals with the susceptibility to failure; (ii) the second component refers to the run-out modeling using the initiation areas as an input. Therefore, this research presents the debris-flow susceptibility assessment in the Zêzere river basin (Serra da Estrela, Portugal). The debris-flow initiation areas are modeled using a bivariate statistical method (Information Value) and the run-out areas are simulated using a simple hydrological algorithm (D-infinity downslope influence). The Area Under the Curve (AUC) determined for the Information Value models ranges from 0.94 to 0.96, which reflect an excellent predictive capability. The most relevant predictor variables are: burned areas, slope above 30º, soil depth less than 75 cm and concave plan curvatures. The run-out modeling of the 36 ruptures areas included in the debris flow inventory delivered a true positive rate of 80.5%, reflecting a good performance of the model.