Due to inability to entirely prevent debris flow and snow avalanches, it is reasonable to develop
mathematical models that allow us to predict and design sufficient protection measures in endangered
areas. One dimensional model PLAZEM15 allows analysis of unsteady flow of fluids, such as free
surface water flow, debris flow and snow avalanches. Theoretical background for mathematical
modeling of unsteady flow of fluids and their impact force is described in the first part of the thesis.
Further on the thesis describes results of sensitivity analysis of the model in which the initial shear
stress, viscosity of the debris material and topographic parameters, including changes in the slope of
the channel bed and gradual extension of channel width, were modified. The impact of changes in
topography was examined for debris flow and snow avalanches. These simulations were already made
in 1980 in the frame of the Chair of Fluid mechanics of the faculty, and the results were compared. In
the last part of the thesis calculations of the impact force of flow were made for selected cases of
debris flow and snow avalanches.
The final results of the analysis showed, that tested numerical models give basically good results,
however, further verification will be necessary before final applications. Comparison with results of
some field measurements, not available in this study, would be very important.