GCOS has recognized a new affiliate to its global observation network for river system observations
The Global Climate Observing System (GCOS) regularly assesses the states of global climate observations of the atmosphere, land and ocean and produces guidance for their improvement. In March, GCOS recognized a new affiliate to its global observation network, for river system observations.
River systems are an integral part of the global water cycle, linked to many local, regional and global Earth system processes. River discharge is an important driver in the climate system, recognized as Essential Water Variable (EWV, GEOSS, 2014) as well as an Essential Climate Variable (ECV) as defined by GCOS (GCOS-245, 2025). The statistical properties of river discharge are an indicator for climatic change and variability, reflecting changes in precipitation and evapotranspiration. Such statistics are also required for the calibration and validation of satellite data, global models, trend analysis and socioeconomic investigations.
The Global Runoff Data Centre (GRDC) is an international data repository, which collects historical river discharge data at a global scale. Established in 1988, the GRDC holds the most substantive collection of quality assured river discharge data worldwide. GRDC operates under the auspices of WMO at the German Federal Institute of Hydrology (BfG) in Koblenz, Germany. The collection and dissemination of long-term hydrological data and information on a global scale is the principal reason for its operation. Key partners for the provision of river discharge data are National Meteorological and Hydrological Services (NMHS) of WMO Members.
Since its inception, GRDC has been part of the Global Terrestrial Network - Hydrology (GTN-H), supporting the hydrological observation components of both of GCOS and WMO. In the early 2000s, the Global Terrestrial Network for River Discharge (GTN-R) was established as a component of GTN-H. GTN-R represents a subset of GRDC river discharge stations located near the mouths of the world's major rivers to quantify the amount of riverine freshwater flowing from the continents into the oceans. Currently the GTN-R includes more than 300 river discharge stations with long-term discharge time series of up to more than 200 years. The dataset is fundamental for assessing water resources at the global level and their changes due to climate variability and change. By providing freshwater flux data into the oceans, GTN-R also provides valuable information for marine observations such as ocean salinity and circulation.
In March, the GTN-R successfully completed the accreditation process to be recognized as a GCOS Affiliated Network. Though they are not an integral part of GCOS, GCOS Affiliated Networks are overseen by GCOS, annually report to GCOS and have representation at GCOS Meetings. The GTN-R dataset can be found as a special dataset as part of GRDC using the following link:
