FloodHub diachronic mapping service in the transboundary Evros river basin

Among the natural disasters, flood had the highest occurrence in 2022 (176 in a total of 387), the second highest death toll (7.954 in a total of 30.704), and the second highest human impact (57.1 in a total of 185) according to the most recent annual report “2022 Disasters in numbers” published by the Centre for Research on the Epidemiology of Disasters (CRED) Université Catholique de Louvain, and the United States Agency for International Development (USAID). Decision makers and civil protection authorities need reliable flood situation awareness in order to improve flood resilience and rapid response during a severe flood. For this purpose, the FloodHub Diachronic Mapping Service has been developed by the Operational Unit “BEYOND Center of Earth Observation and Satellite Remote Sensing”, IAASARS, National Observatory of Athens (NOA). It is implemented operationally in the transboundary river basin of Evros (Greece-BulgariaTurkey), in the framework of the Balkan Flood Pilot of the Working Group Disasters of the Committee on Earth Observation Satellites (CEOS). Evros is a river basin where severe floods occur almost every year, and it was recently affected by a catastrophic wildfire which burnt around 94,000 hectares in August 2023. The FloodHub Diachronic Mapping Service is based on a fully automated system that searches, downloads and preprocesses Sentinel-1A/B SAR data and then, using machine learning, automatically maps water surfaces in a user-defined area. It uses the Copernicus Dataspace Ecosystem and covers the time period since 2018. It also includes the burnt scar mapping produced by the FireHub Diachronic Mapping Service, which is a fully automated system since 1984 using Sentinel-2 (now) and Landsat (earlier) data. This is very important in order to examine the impact of the wildfires on the floods. The FloodHub Diachronic Mapping Service is a reliable flood mapping tool in line with the requirements for the implementation of the EU Floods Directive 2007/60/EC, the Sendai Framework for Disaster Risk Reduction, the UN SDGs, as well as the GEO’s Societal Benefit Areas.