The CEMS Hydrological Data Collection Centre Annual Report 2023 : report prepared by the CEMS Hydrological Data Collection Centre in collaboration with the European Commission Joint Research Centre

The Copernicus Emergency Management Service (CEMS) Hydrological Data Collection Centre (HDCC) is responsible for the collection, quality control, harmonisation and internal distribution of hydrological observations (river discharge, water level and reservoir variables) for both the CEMS European Flood Awareness System (EFAS) and the Global Flood Awareness System (GloFAS). The Joint Research Centre (JRC) of the European Commission is the entrusted body overseeing the management, technical implementation and evolution of the CEMS EFAS and GloFAS. Ghenova Digital is the designated contractor responsible for implementing the operational functionalities of the CEMS HDCC. This report contains an analysis of the hydrological data collected throughout 2023, alongside a description of the data-collection and quality-control protocols employed. In 2023, the CEMS HDCC welcomed two new data providers and expanded the number of stations providing near real-time and historical hydrological data for both the European domain (CEMS EFAS) and the global domain (CEMS GloFAS). In 2023, 52 data providers delivered near real-time discharge and water level data to CEMS EFAS, for a total of 2,634 hydrological stations. Additionally, throughout this year the number of stations in the CEMS GloFAS database increased by 675, bringing the total to 3,216 (of which 3,176 with data). In 2023, the processes for collecting and validating reservoir data within the European domain were implemented. Five institutions provided reservoir data and characteristics, contributing data from 88 reservoir stations to the HDCC database. The analysis of near real-time data for the European domain revealed noteworthy findings regarding the hydrological conditions observed in 2023.