BEYOND DENSE Flow AVALANCHES (bDFA)

Abstract

The final report summarizes - primarily the progress that has been achieved during the second project year (April 1, 2017 to July 31, 2018) of the ESS project bDFA – beyond dense flow avalanches (Quantifying the destructive reach of snow avalanches beyond the dense flow regime) - and highlights the major achievements that have been gained during the entire project period April 1, 2017 to July 31, 2018. The project aims at the analysis and improvement of avalanche simulation tools, primarily of the Swiss tool RAMMS::AVALANCHE and the Austrian tool SamosAT. At first, damage back-calculations of documented events and a damage catalogue have been completed. Additional data have been investigated on damages of avalanche gullies and on the recent avalanche disaster in Farindola, Italy. Furthermore, the expert interview conducted in the first project year was completed and evaluated. In total 51 participants from various countries have participated. Major results are about to be published. Progresses could be achieved at the Vallee de la Sionne test site. Here, the installation of pressure sensors was completed and in cooperation with the Ruhr-Universitat Bochum (RUB) a novel radar system has been developed to measure snow concentration and density in powder snow clouds. First measurements of artificially released avalanches could be made. Findings within the second project period suggest that the flow variable – pressure relation represents the he missing link between current bDFA models and impact pressures and therefore bDFA damages. Therefore, three-dimensional Eulerian multiphase fluid dynamic simulations with OpenFOAM have been performed and a unified framework for snow avalanches has been established. The finalization of Back-calculations of avalanches from Switzerland and Austria has been realized within the second and third project year. Therefore, 9 avalanches from both countries have been simulated using RAMMS and SamosAT. Because of a new version release of SamosAT, the calibration of an adjusted parameter has been pushed forward and implemented in a preliminary form. Further a comparison between the two simulation tools has been initiated. Finally, vulnerability functions describing the aversive effects of powder snow avalanches on massive constructed buildings as they are typical for the Alpine region have been derived. The basis of that work is a wide investigation of documented damage events in Tirol. An approach that relates classified damages to monetary values.