Mathematical modelling is a common approach when assessing debris-flow hazards. In this study on the mathematical modelling of debris flows, we applied the widely used Flo2D model. The high accuracy ...of the input parameters is essential for obtaining acceptable results. The numerimi grid in the area of the debrisflow movement is generated from topographic data. The aim of our research was to assess the usefulness of public data for debrisflow-modelling and to compare this data to the LiDAR-derived data. In Slovenia, DEM 5 and DEM 12.5 are publicly available data. However, the morphological accuracy of these dataseis is questionable because of their development methods and their low morphologic resolution. A better solution is LiDAR-derived data with higher resolutions and a multiple options for further improvements with different methods and algorithms. The results with LiDAR data are more accurate-, the torrential channel is better expressed. One downside of LiDAR data is its high price, which prevents wider usage of more precise data. Another downside is the much longer computational times of the model. More precise data means a more agitated surface of the computational grid, which results in shorter computational steps to ensure numerical stability. Methods for LiDAR-derived DEMs improvements are proposed in this study. With modified data, computational times are much shorter and results are even more precise than with non-modified DEMs.
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