communication mediumÖsterreichische Wasser- und Abfallwirtschaft, Vol.74
The present article summarises the strategy and methodological steps of the HORA 3.0 project, in which flood risk zones have been calculated for all of Austria. The analysis steps include: quality control and correction of the stream network and the catchment boundaries; estimation of flood peaks and volumes of a given return period; establishment of a digital elevation model that matches all relevant flood information, including river bed geometry; unsteady, two-dimensional simulations of flood inundation patterns with consistent return periods. In each step, automatic and manual methods are combined in order to map the local hydrological and hydraulic conditions as accurately as possible in a nationwide project. The flood risk zones with a resolution of 2 m for a total river length of 32,000 km have already been published on the HORA platform (www.hora.gv.at). The methodologies developed can be used for further projects, e.g. for visualizations, damage evaluations and in the future for the mapping of pluvial flood hazards.