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European Flood Alert System (EFAS)

The European Flood Alert System is a flood forecasting system currently under development and testing at the European Commission DG Joint Research Centre in close collaboration with National Hydrological and Meteorological Services. The system was launched by the European Commission following the devastating Elbe and Danube floods in 2002 with the aim to provide National Hydrological Services with medium-range flood forecasting information on river basin scale across Europe.

Technically, EFAS is based on the physically-based distributed hydrological model LISFLOOD and is driven by observed meteorological data and medium-range weather forecasts including full sets of Ensemble Prediction System. Its output consists of probabilistic information on floods in the medium-range (3-10 days) for trans-national river basins in Europe. In case that a high probability of flooding is forecasted in 3-10 days, the partner organizations are contacted with detailed information from the EFAS system.

EFAS outputs are also evaluated against historic observations and skill is assessed through case study analysis and statistical skill score assessments. One important objective of EFAS is to further research in probabilistic flood forecasting in operational applications. It is planned that the pre-operational system will be transferred to an operational entity by 2010.

Appropriate Use EFAS results are not public information but provided only to experts, e.g. hydrological experts in the National Hydrological Services, as early flood warning information. EFAS ensures that the partners are informed about EFAS output through training documents and workshops and understand how to understand the probabilistic results.
Scope EFAS covers medium-large trans-national river basins in Europe.
Key Output Medium-range flood probability maps, ensemble streamflow output, meteorological rainfall information, media-monitoring on floods made accessible through a web-based interface.
Key Input Key input can be split into dynamic data, e.g. observed meteorological data, rainfall, temperature, evaporation, weather forecast data including EPS, observed discharge data, and static data, e.g. maps of topography, land-use, soil, river network.
Ease of Use EFAS information consists of specific products for flood forecasting experts and therefore requires a good understanding of flood forecasting and hydrological processes. The information is made accessible through a web-interface which is easy to use. Concise manuals and training documents guide the user through the different applications and online explanation is also provided directly through the web interface.
Training Required Expert knowledge on hydrological forecasting is required to understand the specific products and how to use them. Training is provided through documents, meetings and discussions.
Training Available Training documents, manuals, meetings.
Computer Requirements In order to run EFAS as a system a Linux cluster is needed, a database and a substantial file storage system for model input/output (capacity in the order of several TBytes). The system is programmed in a dynamic GIS language (PCRaster) and Python scripting. In order to view the results, the EFAS web-interface is based on Windows and accessible through any web browser.
Documentation Can be found on the EFAS webpage

Since 2005 EFAS information is provided to about 24 National hydrological services across Europe in case flooding is forecasted more than 3 days in advance. The system was active and successful during a number of serious floods in the past, including the Danube floods in 2005 and 2006, the Elbe floods in 2006, Rhine floods 2007. Medium-smaller scale floods were also covered by EFAS and reported to the partner organizations.

Contacts for Framework, Documentation, Technical Assistance

General information can be found at

Contact points for specific questions on EFAS at the Joint Research Centre are and

Cost General Information on EFAS and its research results are provided free of charge. Flood forecast information can only be provided on formal agreement to experts in National Hydrological Services and are free of charge.

De Roo, A., B., Gouweleeuw, J. Thielen, P. Bates, A. Hollingsworth, et al. 2003. Development of a European Flood Forecasting System. International Journal of River Basin Management 1(1):49-59.

De Roo, A., J. Thielen and B. Gouweleeuw. 2002. LISFLOOD, a distributed water balance, flood simulation and flood inundation model. User manual. Version 1.0. Report of the European Commission, Joint Research Centre, Special Publications No. I.02.131.

De Roo, A., M.H. Ramos, J. Thielen, G. Franchello, J. Bartholmes, K. Wachter, S. Niemeyer, M. Kalas, G. Laguardia and J. van der Kniff. 2006. The Alpine floods of August 2005. What did EFAS forecast, what was observed, which feedback was received from end-users? EFAS Post-event summary report, European Commission, EUR 22154 EN, 94pp.

Feyen, L., J.A. Vrugt, B. Ó Nualláinc, J. van der Knijff and A. de Roo. 2007. Parameter optimisation and uncertainty assessment for large-scale streamflow simulation with the LISFLOOD model. Journal of Hydrology 332(3-4):276-289.

Gouweleeuw, B., J. Thielen, G. Franchello, A. de Roo and R. Buizza. 2005. Flood forecasting using medium-range probabilistic weather prediction. Hydrological and Earth System Sciences 9(4):365-380.

Gouweleeuw, B., P. Reggiani and A. De Roo (eds.). 2004. A European Flood Forecasting System EFFS. Full Report. European Report EUR 21208, EC DG JRC & WL Delft Hydraulics, 304pp.

Kalas M., M.H- Ramos, J. Thielen and G. Babiakova. In press. Evaluation of the medium-range European flood forecasts for theMarch - April 2006 flood in the Morava River. Journal of Hydrology and Hydromechanics.

Ramos. M.H., J. Bartholmes, J. Thielen-del Pozo. Development of decision support products based on ensemble forecasts in the European Flood Alert System, submitted to Atmospheric Science Letters.

Thielen, J., J. Bartholmes, M.-H. Ramos, M. Kalas, J. van der Knijff and A. de Roo. 2006. Added value of ensemble prediction system products for medium-range flood forecasting on European scale. In: Proceedings of the workshop “Ensemble Predictions and Uncertainties in Flood Forecasting”, International Commission for the Hydrology of the Rhine Basin (CHR), Bern Switzerland, 30-31 March 2006, p.77-82.

Thielen J., M.H. Ramos, J. Bartholmes, A. de Roo H. Cloke, F. Pappenberger and D. Demeritt. 2005. Summary report of the 1st EFAS workshop on the use of Ensemble Prediction System in flood forecasting, 21-22nd November 2005, Ispra. European Report EUR 22118 EN, European Commission 2005, 23pp.

Van Der Knijff, J. and A. de Roo .2006. LISFLOOD – distributed water balance and flood simulation model. User manual (2006), European Commission Report EUR 22166 EN, 60pp.

For an updated list of references find information on the EFAS webpage: