Urban flood prevention based on ensemble precipitation forecasts

Abstract

Sophisticated strategies are required for flood warning in urban areas regarding convective heavy rainfall events. An approach is presented to improve short-term precipitation forecasts by combining ensembles of radar nowcasts with the numerical weather predictions COSMO-DE-EPS of the German Weather Service. The combined ensemble forecasts are produced operationally every 5 min. Applications involve the Flood Warning Service Hamburg (WaBiHa) and real-time hydrological simulations with the model KalypsoHydrology. Ensemble forecast flood hydrographs for the urban catchment Kollau are presented in this work. The range and quantiles are illustrated for a convective storm event in summer 2016. A flood management measure is improved by using precipitation forecasts in a flood control reservoir.