EFAS provides different flash flood indicators based on two main concepts: 1) ERIC, generated from high-resolution numerical weather predictions with a lead time of up to 5 days, and 2) ERICHA, based on radar-based precipitation monitoring and nowcasting for the next 6 hours. In addition another flood impact product called TAMIR is provided, combining radar precipitation products and ensemble medium range precipitation forecasts

ERIC - Numerical weather prediction based flash flood indicator

The ERIC flash-flood indicator is generated by comparing the forecasted surface runoff accumulated over the upstream catchment with a reference threshold. It is based on the 20-member COSMO-LEPS ensemble precipitation and soil moisture forecasts from the LISFLOOD hydrological model and provides indicators of flash flooding for the next 5 days.

The ERIC flash flood indicators modelling chain.
The ERIC flash flood indicators modelling chain.

 

Two ERIC products exist:

  • Reporting points (“ERIC Reporting Points” layer): points in the river network where flash flooding is possible. Enlarged triangles highlight where the flash flood forecast probability over the next 5 days meets the notification criteria in terms of threshold exceedance probability and lead time of threshold exceedance (Find the criteria in the EFAS Wiki under ERIC reporting points). The ERIC reporting points provide the fundamental information upon which Flash Flood Notifications are generated and then distributed to the EFAS partners.
  • Affected area (“ERIC Affected Area” layer): river network which contributes to each ERIC reporting point, i.e. areas at risk from flash flooding. Read more in the Wiki under ERIC Affected Area
     

ERICHA - Radar-based precipitation monitoring and nowcasting flash flood indicators

The ERICHA flash-flood indicator is generated from radar-based precipitation monitoring and nowcasting product, based from the European OPERA radar composite. It aims to capture very localised events difficult to predict from numerical weather prediction systems.

The chain of the updated ERICHA system producing precipitation and flash flood hazard nowcasts.
The chain of the updated ERICHA system producing precipitation and flash flood hazard nowcasts.

Three ERICHA products exist:

  • Hourly precipitation maps: Hourly precipitation totals from the OPERA radar composite for the previous ~48 hours and the predicted precipitation for the next 6 hours, updated every 15 minutes  (“ERICHA hourly accumulation precipitation” layer). Read more in the Wiki under ERICHA Hourly Accumulated Precipitation.
  • Daily precipitation maps: Daily gauge-adjusted radar rainfall accumulation over the preceding 24 hours, , only available for the past 7 days, generated at 00 and 12 UTC every day ("ERICHA 24-h accumulations" layer). Read more in the Wiki under ERICHA 24-h accumulations.

Advanced Tools for pro-Active Management of Impacts and Risks induced by convective weather, heavy rain and flash floods in Europe


In addition to the ERIC and ERICHA products, there are several TAMIR products available in the EFAS Map Viewer, combining radar precipitation products (OPERA) and ensemble medium range precipitation forecasts, and translating it into a flood impact product. 

For more information

Alfieri, L., Thielen, J., 2015: A European precipitation index for extreme rain-storm and flash flood early warning. Meteorol. Appl., 22(1), 3–13, doi:10.1002/met.1328

Berenguer, M., Sempere-Torres, D., Pegram, G.G.S, 2011: SBMCast - An ensemble nowcasting technique to assess the uncertainty in rainfall forecasts by Lagrangian extrapolation. Journal of Hydrology 404 (3-4), 226-240, doi:https://doi.org/10.1016/j.jhydrol.2011.04.033

European Rainfall-InduCed Hazard Assessment system (ERICHA) - http://www.crahi.upc.edu/ericha/index.php?option=com_content&view=article&id=44&Itemid=29&lang=en

Fundel, F., Walser, A., Liniger, M.A., Frei, C., Appenzeller, C., 2010: Calibrated precipitation forecasts for a limited-area ensemble forecast system using reforecasts. Monthly Weather Review, 138(1), 176-189, https://journals.ametsoc.org/doi/10.1175/2009MWR2977.1

Park, S.; M. Berenguer, and D. Sempere-Torres, 2019: Long-term analysis of gauge-adjusted radar rainfall accumulations at European scale. Journal of Hydrology, 573, 768–777, https://doi.org/10.1016/j.jhydrol.2019.03.093

Raynaud, D., Thielen, J., Salamon, P., Burek, P., Anquetin, S., Alfieri, L., 2015: A dynamic runoff co-efficient to improve flash flood early warning in Europe: Evaluation on the 2013 central European floods in Germany. Meteorological Applications, 22(3), 410–418, doi:10.1002/met.1469