The European Flood Alert System – Part 1: Concept and development

Abstract

Abstract. 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 mediumrange 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. The ensemble of different hydrographs is analysed and combined to produce early flood warning information, which is disseminated to the hydrological services that have agreed to participate in the development of the system. In Part 1 of this paper, the scientific approach adopted in the development of the system is presented. The rational of the project, the systems set-up, its underlying components, basic principles and products are described. In Part 2, results of a detailed statistical analysis of the performance of the system are shown, with regard to both probabilistic and deterministic forecasts.

Ensemble flood forecasting in Africa: a feasibility study in the Juba–Shabelle river basin

“…In EFAS, a flood alert is emitted if the discharges exceed critical thresholds (low, medium, high and severe) and if the exceedance has been sufficiently persistent over previous forecasts (the EFAS decision support rules; Ramos et al, 2007;Bartholmes et al, 2009;Thielen et al, 2009). For EPS-based forecasts, an event is defined if a certain number of EPS (i.e.…”

Operational forecast uncertainty assessment for better information to stakeholders and crisis managers

“…They differ in the uncertainty source(s) they take into account, their theoretical grounds and their usability for operational real-time purposes. Thus, methods like the multi-model approach [14,15], the GLUE method [16] or ensemble forecasts [17,18] only consider a few uncertainty sources (respectively, the model uncertainty, the parameter uncertainty, and for the latter the meteorological input uncertainty most often). GLUE is built on a (very) simplified theoretical framework whereas Bayesian approaches [19,20,21] intend to be more rigorous in expliciting assumptions (model error embedded in the likelihood function).…”

Improving Flood Prediction Assimilating Uncertain Crowdsourced Data into Hydrological and Hydraulic Models

“…De Roo et al (2003) developed a European-scale flood forecasting system (EFFS) using ECMWF's deterministic and ensemble prediction system as input for a distributed hydrological-hydraulic modelling framework. Thielen et al (2009) presented the European Flood Alert System (EFAS) in order to provide local water authorities with medium-range (lead time from 3 to 10 days) probabilistic flood forecasting in order to increase preparedness and promote a culture of risk prevention. Jaun and Ahrens (2009) studied the advantages and limitations of probabilistic forecasting systems as opposed to deterministic ones.…”