Modeling of a debris flow from the Hrenovec torrential watershed above the village of Kropa

In this paper, debris-flow modeling is shown specifically on the basis of a potential debris flow from the Hrenovec torrential watershed above the village of Kropa in NW Slovenia. This site was chosen, because in this particular torrential watershed a small surficial landslide turned into a debris flow during a storm on September 18, 2007. Fortunately, the debris flow stopped inside the torrential channel above the village of Kropa. Using public available data on rainfall and topography, we developed two scenarios of debris-flow triggering with an estimated magnitude of 50,000 m3. According the first scenario, a debris flow triggers during rainfall with the 100-year return period, and according the second one, it triggers during extreme rainfall as measured during the storm on September 18, 2007. For both scenarios, we used for debris-flow modeling a commercial two-dimensional mathematical model Flo-2d. The obtained results are shown in the form of computed flow depths and velocities over a cartographic background. The results show to possible catastrophic consequences in the village of Kropa, much worse that set in by torrential flood during the storm on September 18, 2007