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REGIONAL ROCKFALL HAZARD ASSESSMENT IN THE BENASQUE VALLEY (CENTRAL PYRENEES) USING A 3D NUMERICAL APPROACH (2002)
Rockfall hazard assessment is a fundamental land planning tool in high mountain area. In this paper, a new rockfall hazard methodology is applied, based on the results of a 3D rockfall numerical model performed through an original simulation code. This is based on a lumped mass algorithm and allows to simulate rockfall motions in a spatially distributed way on a 3D topography described by a DTM. Model results can be combined in a GIS in order to produce physically based rockfall hazard maps according to a 3D matrix approach providing both a positional “hazard index” and a “hazard vector”. The method has been tested at a regional scale in the Benasque basin, a 290 km2 mountain area in the Huesca Province (Central Pyrenees, Spain). A DEM with cell size of 25*25 m has been used to describe topography. Information concerning lithology, geomorphology and vegetation of the area have been combined in a unique condition map to characterise the different slope materials and to identify outcropping areas and rockfall source areas. The model has been run with a stochastic approach and calibrated by geomorphological observations. Results have been combined in a 3D hazard rating matrix to obtain positional and vector hazard indexes. Different hazard maps has been produced in order to outline the exposed areas and to evaluate possible land planning solutions.
Mediterranean Storms (Proceedings of the 4th EGS Plinius Conference held at Mallorca, Spain, October 2002)
Instituto Geologico y Minero de Espana