Global River Discharge Dropped to 35-Year Low in 2025
Satellite and ground-based data reveal a seven-year trend of declining water levels and shrinking glacial mass.
Updated on Sept. 30, 2026 in Environmental
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In 2025, global river discharge reached one of the lowest levels recorded in 35 years. This retrospective assessment confirms that 36% of river basins experienced below-normal flows, marking seven consecutive years of water levels failing to meet the 1991-2020 historical average.
Why it matters
The persistent decline in terrestrial water storage and the fourth consecutive year of global glacial mass loss threaten water security across multiple continents. These shifting hydrological patterns are increasingly linked to extreme events, with Asia and Africa suffering the highest mortality rates.
Findings were aggregated from more than 3,000 monitoring stations across 68 countries. Data integration relied on satellite observations and hydrological modeling to track shifts in terrestrial water storage, which has seen a sustained decline since the 2014-2016 period.
The players
Global Hydrological Monitoring Network
An international coalition of 68 countries and 3,000 monitoring stations that provide satellite and ground-based observations.
The details
Researchers utilized satellite remote sensing and ground-level hydrological monitoring to map river discharge and water storage anomalies. The process involves measuring terrestrial water storage—the total amount of water stored on the Earth's surface and in the soil—to quantify shifts away from historical norms. With two-thirds of monitored global boreholes showing significant deviations, the model highlights a multi-year trend of depleting subterranean and surface water reserves.
Timeline
1991-2020: Historical baseline period for normal river basin states.
2014-2016: Beginning of the decline in terrestrial water storage.
2023-2025: Period of cumulative glacial mass loss totaling 1,400 gigatonnes.
2025: Year of historically low global river discharge.
The Tech Race
This assessment updates the established trend relative to the 1991-2020 hydrological baseline period. It marks a critical departure from historical norms, as water levels have failed to return to the baseline average for seven consecutive years.
Communities in Asia and Africa remain the most vulnerable to water-related disasters, accounting for over 80% of deaths in the last five years. These hydrological changes signal increased pressure on regional infrastructure and local agricultural water security in affected areas.
The takeaway
The data demonstrates a clear, multi-year degradation of global water stability that has persisted well beyond previous short-term fluctuations. Watch for future updates from the monitoring network to see if 2026 flow rates show any deviation from this downward trajectory.
Further reading
For broader context on these shifts, see our coverage of Environmental trends.
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