Towards improved hydro-meteorological ensemble forecasting for flood warning in small catchments in Saxony, Germany

Flood forecasting and warning for small catchments are challenging due to the short response time of the catchments on heavy rainfall events. Thus, disaster managers are interested in extended lead times to initiate flood defence measures, which can be obtained by employing forecasts of numerical weather models as driving data for hydrological models. To portray the inherent uncertainty of weather model output, ensemble hydro-meteorological forecasts can be used.

By this contribution, we introduce the next steps to improve our operational web-based demonstration platform for ensemble hydrological forecasting in small catchments of Saxony, Germany (http://howa-innovativ.hydro.tu-dresden.de/WebDemoLive/). In its current configuration, it uses the Icon-D2-EPS numerical weather prediction product of the German Weather Service (DWD) and provides a hydrologic forecast ensemble of 20 members each three hours, for lead times up to 27 hours. The system is established for three pilot regions with different hydrological settings in Saxony, Germany. Within the second funding period of the HoWa-project improvements are planned for three main parts of the hydro-meteorological ensemble prediction platform considering a) the for observed and forecasted precipitation input, b) the hydrological forecast modelling, and c) the post-processing, visualisation and communication of results including their uncertainty.

In terms of precipitation input we are going to incorporate radar based nowcasting for short term forecasts of the next two hours. Furthermore, we will enlarge the maximum forecast period to 48 hours by exploring the full range of the Icon-D2-EPS NWP forecasts. In addition, forecasts will be updated more frequent. Regarding the hydrological forecasting features will be implemented for flood reservoir operation, and the numbers of catchments/regions will be increased. Finally, a new web-based visualisation dash board will be developed to allow for user oriented analysis and configuration. First steps towards these improvements will be presented.