The International Centre for Water Resources and Global Change (ICWRGC) has contributed to the World Meteorological Organization (WMO) State of Global Water Resources 2025 report through two of the global water data centres jointly operated with the German Federal Institute of Hydrology (BfG): the International Soil Moisture Network (ISMN) and the GEMS/Water Data Centre (GWDC). BfG also hosts the Global Runoff Data Centre (GRDC), which contributed river discharge data to the report.
Published annually by WMO, the State of Global Water Resources report provides a comprehensive science-based assessment of the global hydrological cycle, its variability and water-related extremes. The 2025 edition brings together observations, satellite products and modelling results to provide a global picture of water resources and support evidence-based water management and decision-making.
Global observations for a global assessment
ICWRGC’s contribution demonstrates the important role of global data centres in bringing together observations from national and regional monitoring networks and making them accessible for international assessments.
For the 2025 report, the International Soil Moisture Network (ISMN) contributed in situ soil moisture observations and analysis. Around 800 in situ measurements from ISMN across North America, Europe and Australia were used to validate the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) Satellite Application Facility on Support to Operational Hydrology and Water Management (H SAF) global root-zone soil moisture product used in the report.
The report additionally presents an ISMN-based case study of observed soil moisture anomalies in the United States, illustrating conditions at different soil depths. In 2025, soil moisture conditions showed strong regional and seasonal contrasts, with dry conditions across much of South America, the Middle East, Europe and parts of North America, while wetter-than-normal conditions occurred in India and parts of Africa (see pages 33–34 of the report).
The GEMS/Water Data Centre, which operates GEMStat, the global water quality database, contributed to the assessment of observed water quality. The 2025 report presents observed river water-temperature conditions based on data compiled from national water agencies. Following quality and data-coverage requirements, observations from 432 stations across five countries were included in the assessment. The report shows persistent above-normal river temperatures across Asia and the Middle East, while South America and major river basins in Africa showed near-normal river temperatures (see pages 44–45 of the report).
The Global Runoff Data Centre (GRDC), hosted by BfG, contributed river discharge observations to the assessment. The resulting global assessment shows that 2025 was one of the driest years for river discharge in the past 35 years, continuing a period of unusually variable river flows.
From national observations to global knowledge
The contributions highlight a central function of ICWRGC and the data centres it hosts: facilitating the flow of hydrological information from monitoring networks and national institutions into globally accessible datasets, analyses and international assessments.
“Through global water data centres, we build a bridge between national monitoring networks and global analyses. Our contribution to the WMO Report 2025 demonstrates how international cooperation transforms fragmented observations into accessible knowledge in order to sustainably protect and manage water resources worldwide. The report clearly demonstrates growing water-related risks that require enhanced resilience through better water management, preparedness and adaptation.”
– Dr. Stephan Dietrich, Director ICWRGC
Reliable assessments of global water resources depend on sustained observations and effective international data exchange. Global data centres help connect data providers, researchers, international organizations and users while supporting the harmonization, quality control and long-term availability of observations.
This becomes increasingly important as water conditions become more variable and extreme. The 2025 WMO report documents substantial anomalies across different components of the global water cycle, including river discharge, terrestrial water storage, glaciers, soil moisture and water quality. At the same time, although global water-data availability continues to improve, important observational gaps remain, particularly in regions strongly affected by water-related hazards.
Strengthening international cooperation on water data
Through its global data centres and its cooperation with WMO, UNESCO and national and international partners, ICWRGC supports efforts to strengthen the observational basis for understanding changes in the global water cycle.
“Germany contributed to this report through four global data centres. We do not own these data centres solely for our own benefit; Germany firmly believes in open data and open science.”
– Amb Antje Leenderste, German Permanent Representative to UN and International Missions
Such international cooperation enables observations collected locally and nationally to contribute to a broader understanding of water resources at regional and global scales. In turn, this knowledge provides an important scientific basis for water-resources management, climate adaptation, drought and flood preparedness, ecosystem protection and sustainable development.
The contribution to the WMO State of Global Water Resources 2025 report therefore reflects a wider objective of ICWRGC: bridging water-data gaps and transforming fragmented observations into accessible global knowledge that can support more informed and sustainable water management.
Further information:
The WMO State of Global Water Resources 2025 report is published by the World Meteorological Organization (WMO).
