Satellite data reveal the human fingerprint on water storage
A NASA analysis links water storage changes in 40 regions to irrigation, reservoirs and land use. The more detailed map also has a temporal-resolution tradeoff.
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Irrigation, reservoirs and changes in land use leave a measurable fingerprint on terrestrial water storage. On 20 October, NASA Earth Observatory presented an analysis of satellite data covering April 2002 to November 2025.
Researchers use measurements of Earth's gravity from the GRACE and GRACE-FO missions. They identify 40 regions where water storage changes are statistically associated with human activities as well as climatic factors.
Combining years of observations provides five to ten times more spatial detail. The tradeoff is less temporal detail: the map shows long-term trends, not the amount of water available on a particular day.
Examples include groundwater declines in California and northern India associated with irrigation. Elsewhere, water storage increases because of reservoirs or changes in land use. This does not mean all human interventions have the same effect.
The findings were published in the scientific journal PNAS. The analysis is not a forecast for water supplies in Bulgaria.
Sources: NASA Earth Observatory; O’Neill and colleagues, PNAS, 2026.
Illustrative photo: Luis Tosta / Unsplash, Unsplash License. A tap with a drop of water, not the satellite image from the study. Cropped to 1200×675 px.
