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The following is a description of the latest operational release of EFAS v4.7. For EFAS v5.0. For an overview of other EFAS releases, please see: EFAS versioning system.

Summary

EFAS v4.7 enables the visualisation of the new Global Flood Monitoring (GFM) products in the CEMS EFAS map viewer. The GFM provides continuous monitoring of floods worldwide, by automatically processing and analysing in near real-time all incoming Synthetic Aperture Radar imagery acquired by the EU’s Copernicus Sentinel-1 satellites. Here is a summary of the main changes:

The GFM product is based on 3 different flood detection algorithms running in parallel and is composed by 11 different layers, roughly grouped into 4 categories: water bodies (Observed Flood Extent, Observed Water Extent, Reference Water Mask), uncertainty-related (Exclusion mask, Uncertainty values, Advisory flags), S1 data specifics (metadata, footprint, schedule) and impacts estimate (Affected population, Affected land cover).

With a spatial resolution of 20m and a revisit time ranging from 3 to 14 days depending on S-1 overpasses, the full dataset of the product output layers is made available in raster format both separately and in bulk.

The information about the specifics of the GFM products and how to access the data are provided through the GFM Product User Manual and the Product Description Document available here

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