Evaluating Land Cover-Based Roughness Scenarios for Fluvial Flood Inundation Modelling

Hodnotenie scenárov drsnosti povrchu založených na krajinnej pokrývke pre modelovanie fluviálnych povodní

Matej Vojtek, Jana Vojteková, Petra Hačková, Zuzana Jakabová

In: Geografické informácie (Geographical Information), Ročník (Volume) 30, Číslo (Issue) 1, 2026, p. 64-76, ISSN 1337-9453

DOI: 10.17846/GI.2026.30.1.64-76

Abstract

Land cover and the derived surface roughness are important parameters affecting the accuracy of hydraulic flood inundation models, as they control flow resistance, depth, and velocity. This study evaluates the impact of land cover-based roughness scenarios on fluvial flood inundation modelling for an 8.8 km reach of the Kysuca River in northern Slovakia. A two-dimensional MIKE+ hydraulic model was developed using a 1 m resolution LiDAR-derived digital elevation model and detailed land use/land cover data from 2023. Manning's roughness coefficients were assigned to individual land cover classes using reference values from the literature and two alternative scenarios representing a 20% decrease and a 20% increase in roughness. Model outputs were compared in terms of flood extent, flow depth, and flow velocity for a 100-year flood event. The results demonstrate that decreasing roughness increases flow velocities while reducing flood depths and inundation extent, whereas increasing roughness produces deeper, more extensive flooding and lower flow velocities. Although the overall spatial pattern of flooding remained similar across all scenarios, notable differences occurred along the main river channel and adjacent floodplain. The findings highlight the importance of accurate land cover-based roughness parameterization for improving hydraulic model reliability and reducing uncertainty in flood hazard assessments.

Keywords: fluvial floods, land cover, surface roughness, hydraulic modeling, scenarios

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