NHESS Natural Hazards and Earth System Sciences NHESS Nat. Hazards Earth Syst. Sci. 1684-9981 Copernicus Publications Göttingen, Germany 10.5194/nhess-10-699-2010 Evaluation of a 3-D rockfall module within a forest patch model Rammer W. 1 Brauner M. 2 Dorren L. K. A. 3 4 Berger F. 3 Lexer M. J. 1 Institute of Silviculture, Department of Forest and Soil Sciences, University of Natural Resources and Applied Life Sciences, Peter Jordanstraße 82, 1190 Vienna, Austria Institute of Mountain Risk Engineering, Department of Civil Engineering and Natural Hazards, University of Natural Resources and Applied Life Sciences, Peter Jordanstraße 82, 1190 Vienna, Austria Cemagref Grenoble, 2 rue de la Papeterie, 38402 Saint Martin d'Héres Cedex, France current address: Division for Hazard Prevention, Federal Office for the Environment (FOEN), 3003 Bern, Switzerland 12 04 2010 10 4 699 711 Copyright: © 2010 W. Rammer et al. 2010 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://nhess.copernicus.org/articles/10/699/2010/nhess-10-699-2010.html The full text article is available as a PDF file from https://nhess.copernicus.org/articles/10/699/2010/nhess-10-699-2010.pdf

Many slopes in the Alps are prone to rockfall and forests play a vital role in protecting objects such as (rail) roads and infrastructure against rockfall. Decision support tools are required to assess rockfall processes and to quantify the rockfall protection effect of forest stands. This paper presents results of an iterative sequence of tests and improvements of a coupled rockfall and forest dynamics model with focus on the rockfall module. As evaluation data a real-size rockfall experiment in the French Alps and two 2-D rockfall trajectories from Austria and Switzerland were used. Modification of the rebound algorithm and the inclusion of an algorithm accounting for the sudden halt of falling rocks due to surface roughness greatly improved the correspondence between simulated and observed key rockfall variables like run-out distances, rebound heights and jump lengths for the real-size rockfall experiment. Moreover, the observed jump lengths and run-out distances of the 2-D trajectories were well within the stochastic range of variation yielded by the simulations. Based on evaluation results it is concluded that the rockfall model can be employed to assess the protective effect of forest vegetation.

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