Page History

Summary

The following is a description of the latest operational release of EFAS v4 v5.80. For an overview of other EFAS releases, please see: EFAS versioning system.

Summary

EFAS v4.8 integrates changes in its meteorological forcing with the use of the new version of the ECMWF-ENS ensemble forecasting system, introduced by IFS cycle 48r1. This change in the forcing data has the following impacts on EFAS:

• Hydrological monitoring:
  • No change in the observation-forced hydrological reanalysis simulations and the ECMWF-HRES-forced forecast initialisation (the so-called fill-up, where observations not yet available).
• Real time forecasts:
  • The spatial resolution of the forcing increases from 18 km to 9 km for the medium-range EFAS forecasts.
  • The sub-seasonal EFAS forecasts are now produced every day, instead of only twice a week for Mondays and Thursdays. The meteorological forcing comes from the new extended range forecasts in 48r1, produced every day for the 00 UTC cycle, on the same 36 km spatial resolution as before.
• Reforecasts:
  
  • EFAS v4.8 will not have a new 48r1-specific hydrological reforecast data set.
• Seasonal forecasts and seasonal reforecasts:
  • There is no impact on the seasonal hydrological modelling system.

More details on the 48r1 meteorological modelling changes can be found on the Implementation of IFS Cycle 48r1 page.

Technical details

v5.0 introduces a number of major changes to the system, including:

• a higher spatial resolution. EFAS v5.0 has 1 arcmin/ 0.0166667 degrees resolution (~1.4km), as opposed to all the previous EFAS versions having 5-km resolution.
• a different project system, now based on EPSG4326 instead of ETRS89 Lambert Azimuthal Equal Area Coordinate Reference System (ETRS-LAEA) for previous versions.
• a larger modelling domain whose extension has been enlarged to match the river catchments. 
• an entirely new set of 0.0166667 degrees resolution input maps produced using the most recent research findings, remote sensing, and in-situ datasets.
• major improvements to the open-source hydrological model LISFLOOD.
• a new calibration at 1903 in-situ gauging stations, with a parameter regionalisation performed to estimate the parameters of catchments for which in situ discharge observations were not available.
• newreturn period thresholds and snow water/soil moisture anomaly maps based on a climatology from 1992 – 2022. The EFAS v5.0 river discharge climatology is available at the C3S Climate Data Store.
• updated hydrological post-processing models, recalibrated for EFAS v5.0.
• new flood hazard maps, generated using LISFLOOD-FP at 90m resolution and MERIT hydro DM and EFAS v5.0 reference dataset
• new reforecast configuration (medium-range), with the hydrological reforecast datasets being generated during the operational processing chain
• ERIC based on LISFLOOD surface runoff outputs instead of empirical relationships
• ERIC notification points and reporting points shown only for catchments below 1000km²
• additional flood event information available in the Rapid Impact Assessment pop-out table (see EFAS Rapid Flood Mapping and Rapid Impact Assessment)
• updated exposure information used in Rapid Impact Assessment (see CEMS-Flood flood impact forecasting)
• an updated major rivers layer (see Static Layers Overview)
• new rules for defining dynamic reporting points (see EFAS v5.0 - Dynamic Reporting Points)

This upgrade of EFAS has large impacts on the EFAS modelling results.

Other smaller changes include the adjustment of the temperature evolution graph in the reporting point window, which was corrected to show the average temperature of the whole catchment.

Technical details