Extreme heavy rain — flow velocities

Maximum flow velocities (in m/s) for extensive block rain with 180 mm in 6 h, based on the main phase of the extreme severe weather of 14.7.2021 in the Ahr Valley. The determination was carried out using the hydrodynamic-numeric software HYDRO_AS-2D, which is based as a 2D simulation on the numerical solution of the flat water equation using the finite volume method (DGM as of 2019, consideration of evaporation, leaching, sewerage by flat-rate reduction of precipitation in abh. from land use); Lockwitzbach/Weißeritz with HQ 20; see also explanation in the themed city plan).