Key issues in 3d rockfall modeling, natural hazard and risk assessment for rockfall protection in hřensko (Czechia)

The growing urban development in mountain areas together with climate change increased the need for rockfall research and modeling. Determining rockfall processes and related hazard is still a difficult task because of the complexity and intrinsic stochastic nature of the physics involved. In recent years, numerical simulations of rockfall trajectories became common procedure for evaluating rockfall hazard. Increasing of model accuracy leads to the need for more specific complex calibration, appropriate combination of rockfall modeling tools, as well as careful assessment of rockfall sources, block and slope characteristics. Rockfall modeling issues have been tested in local study areas in Hřensko (Czechia) through HY-STONE 3D software. The Hřensko area is characterised by sandstone landscape with rock plateaus, deep canyons with several levels of steep cliffs, which forms favourable conditions for rockfalls. Different modeling approaches, calibration problems, dependency of model results to parameters, and proposed appropriate countermeasures are discussed. The aim of this paper is to provide a knowledge base for researchers and practitioners involved in projects dealing with rockfall protection