Hydrology and Earth System Sciences www.hydrol-earth-syst-sci.net 1027-5606 1607-7938 13 2 2009 10.5194/hess-13-125-2009 http://www.hydrol-earth-syst-sci.net/13/125/2009/ http://www.hydrol-earth-syst-sci.net/13/125/2009/hess-13-125-2009.html http://www.hydrol-earth-syst-sci.net/13/125/2009/hess-13-125-2009.pdf 125 140 2009-02-05 The European Flood Alert System – Part 1: Concept and development J. Thielen jutta.thielen@jrc.it J. Bartholmes M.-H. Ramos A. de Roo EC, Joint Research Centre, Institute for Environment and Sustainability, Via Fermi 2749, 21027 Ispra (VA), Italy Parc de Tourvoie, BP 4492163 Antony Cedex, France This paper presents the development of the European Flood Alert System (EFAS), which aims at increasing preparedness for floods in trans-national European river basins by providing local water authorities with medium-range and probabilistic flood forecasting information 3 to 10 days in advance. The EFAS research project started in 2003 with the development of a prototype at the European Commission Joint Research Centre (JRC), in close collaboration with the national hydrological and meteorological services. The prototype covers the whole of Europe on a 5 km grid. In parallel, different high-resolution data sets have been collected for the Elbe and Danube river basins, allowing the potential of the system under optimum conditions and on a higher resolution to be assessed. Flood warning lead-times of 3–10 days are achieved through the incorporation of medium-range weather forecasts from the German Weather Service (DWD) and the European Centre for Medium-Range Weather Forecasts (ECMWF), comprising a full set of 51 probabilistic forecasts from the Ensemble Prediction System (EPS) provided by ECMWF. 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