The July 2021 floods across Belgium, Germany, Luxemburg and the Netherlands were unprecedented in the combination of timing and magnitude as well as in casualties and damages. This report presents an assessment of the performance and quality of the service provided by the European Flood Awareness System (EFAS) of the Copernicus Emergency Management Service (CEMS) during such event. 

During the event, EFAS issued 25 notifications: 5 Formal Flood Notifications, 6 Informal Flood Notifications, and 14 Flash Flood Notifications.  The detailed assessment report aimed to evaluate CEMS EFAS service in terms of forecasts accuracy, timely availability, and effective communication.  This report provides a description of the flood event, an analysis of the in-situ hydrological and meteorological observations, an account of CEMS EFAS forecasts, model simulations, and communications. 

The analysis of the report highlighted an overall good performance of the system. Nevertheless, the in-depth investigation of each notification and of the EFAS forecasts and simulations allowed to streamline a number of actions to further improve the service. These actions include the continued update of the EFAS hydrological model set-up to improve simulation accuracy; a review of the criteria for the issue of EFAS notifications; improvements in the communication protocol.

The assessment report is the outcome of the collaboration between EC JRC and the CEMS Hydrological Forecast Centre - Analytics and Dissemination, the CEMS Hydrological Forecast Centre - Computations, the CEMS Meteorological Data Collection Centre, and the CEMS Hydrological Data Collection Centre.