On the operational implementation of the European Flood Awareness System (EFAS)

Within Europe severe flood events are often transboundary, requiring collaboration between several national and regional authorities who are responsible for water and flood management. In these situations, inconsistent or erroneous information may arise, for example, from incomplete communication between authorities or different forecasts, resulting in diverging assessments of the flood event. This chapter discusses the European Flood Awareness System (EFAS), which operates on a pan-European scale to provide coherent flood forecasts and related information at a range of timescales. EFAS serves as an independent reference forecast for most of the hydrological services responsible for flood forecasting in Europe as well as the European Civil Protection. The forecasts produced by EFAS are discussed along with the systematic approach used to ensure the information is beneficial to users. This approach includes an organizational structure that allows experts to focus on their specializations, a modeling chain that takes advantage of the latest developments in hydrometeorological and computational sciences, and an increased focus on user engagement. Since the system is constantly evolving, a snapshot of EFAS as of April 2024 is provided. Alongside an overview of the managerial and technical aspects of the system, case studies are used to illustrate the effectiveness of this system in providing early warning of the potential for flooding to authorities.