The Global Flood Monitoring (GFM) Product of the Copernicus Emergency Management Service (CEMS) provides a continuous monitoring of worldwide flood events, by immediately processing and analysing in near real-time (NRT) all incoming Sentinel-1 Synthetic Aperture Radar (SAR) satellite imagery. Key elements of the GFM Product are the use of a historical time-series or “data cube” of SAR backscatter data, enabling high product timeliness, and implementation of an ensemble method comprising three independent, state-of-the-art SAR-based water and flood mapping algorithms, in order to improve the robustness and accuracy of the flood and water extent maps and to build a high degree of redundancy into the service (Matgen et al., 2020; Wagner et al., 2020; Salamon et al., 2021).
The GFM product is designed to deliver, in NRT, critical information on ongoing floods events to users worldwide, including national authorities, emergency units, research centres, decision-makers and other stakeholders.
The GFM product is specifically designed to address three major user requirements, namely:
The GFM Product is also designed to provide a long-term archive of global flood monitoring data, making it an ideal source of information for planning specific mitigation and preparedness measures regarding future flood events, e.g. designing flood protection systems or calibrating hydrological models. Finally, combining data from the GFM product with data from other Copernicus services (e.g. the Copernicus Climate Change Service) can deliver useful information for addressing the challenges in the area of climate change response management.
At the core of the GFM product are three independent, state-of-the-art algorithms developed by three leading research teams (i.e., LIST, DLR and TU Wien) who are members of the GFM consortium for the systematic, automated delineation of flooded areas and water-bodies based on all-weather, day-and-night Sentinel-1 SAR satellite images. As is described in the following sections, the three GFM flood mapping algorithms are implemented in an “ensemble” approach, in order to ensure an optimal accuracy of the derived flood and water extent maps, and to build a high degree of redundancy into the production service.
The operational implementation the GFM product includes the following key elements:
The purpose of this Product User Manual (PUM) is to serve as the reference document for all end-users and stakeholders of the GFM Product. The PUM provides all the basic information to enable the proper and effective use of the GFM Product and associated data output layers, and describes the functions and capabilities of the GFM Product, its applications and alternative modes of operation, and step-by-step guidance on the procedures for accessing and using the GFM Product. Full technical details on the GFM Product are provided on-line in the Product Definition Document (PDD).
The GFM Product has been developed and implemented under a Framework Contract with the European Commission’s Joint Research Centre (European Commission, 2020), by an international consortium (the “Expert Flood Monitoring Alliance”) consisting of six partners:
The GFM partnership represents Europe’s leading group of scientific experts in the field of satellite-based flood monitoring systems, with a wide-ranging and unique experience in global flood mapping services, and with extensive links with the main information services of Copernicus (the EU’s Earth observation programme), including the CEMS and the Copernicus Land Monitoring Service (CLMS). Starting from the earliest days of satellite-based flood mapping and monitoring methods, the individual members of the GFM consortium have built up unprecedented, complementary capabilities for flood mapping, monitoring, and related disaster risk services, and have accumulated a long history of implementing high-quality, successful applications and projects, and developing the related systems for global data processing and access.