River blockages formed by rock avalanches appear to pose a higher hazard potential than other landslide dams, given the extreme run-out distances and volumes of rock avalanche deposits. Recent research has identified rock avalanche deposits to have internal sedimentology consisting of a coarse surficial material (carapace) and a finer fragmented interior (body) potentially of critical importance to rock-avalanche dam stability. Physical scale modelling of overtopping failure and breach development in rock avalanche dams was used to quantify the influence of this sedimentology on critical breach parameters, and their prediction using existing embankment dam breach technologies. Results from this study indicate that the time to failure for rock avalanche dams is approximately twice that observed for homogeneous dams due to the armouring properties of the carapace; and that peak discharge is not significantly affected by sedimentology. While application of empirical, parametric, dimensional and physically based models indicated that uncertainty associated with predicted dam break discharges could range from ±19% to ±107%, no modelling technique was able to simulate the armouring phenomenon adequately. Comparison of actual and simulated breach evolution shows linear assumptions of breach depth and width development (as observed in homogeneous dams) to be incorrect. In the context of hazard management, the results suggest that empirical regression relationships should be used for rapid assessment of potential dam break flood magnitude.

The aim of this diploma thesis is to determine the extent of territory endangered by dam break flood wave under Plumlov dam, using 2D mathematic modelling of water flow under the dam and in the inundation nearby. Output results of the model are maps of the extent territory with highlighted flood area.