Human Actions Drive Tigris-Euphrates Water Loss
A University of Tehran-led study finds human interventions account for far more water degradation in the basin than climate change does.
Updated on Nov. 2, 2026 in Environmental
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Researchers led by Dr. Ali Darvishi Bolourani of the University of Tehran, with academics from Kuwait, Italy and Australia, report human interventions account for 39.3% of water resource degradation in the Tigris-Euphrates basin, compared with 13.6% for climate change. The study appears in the journal Environmental Science and Policy.
Why it matters
The findings shift attention from climate alone toward dam construction, resource management and agricultural expansion as drivers of the basin's decline. Iraq's water reserves have fallen sharply, and the researchers' projections point to a looming shortfall for a region that depends on these rivers.
The study integrated multi-source satellite data, hydro-climatic analyses and water balance equations over four years, finding average basin precipitation fell 9.6% between 1984 and 2022. Projections point to a water deficit of roughly 10 billion cubic meters by 2035, though the models' assumptions about future policy were not detailed.
The players
Dr. Ali Darvishi Bolourani
A researcher at the University of Tehran who led the study on water degradation in the Tigris-Euphrates basin, with collaborators from Kuwait, Italy and Australia.
University of Tehran
A major public research university in Iran whose academics led the basin study published in Environmental Science and Policy.
The details
The researchers traced the basin's evolution from 1984 to 2022, finding that reservoir storage in upstream dams more than doubled in thirty years and that flow into Iraq fell 25% between 1990 and 2016. Massive dam construction in Turkey, including the 22-dam Southeastern Anatolia Project, along with Iraqi resource management and agricultural expansion, favored upstream development over environmental flows.
Timeline
• 1984 to 2022: Four-decade period of basin change analyzed in the study
• 1990 to 2016: Tigris and Euphrates flow into Iraq falls 25%
• 2025: Iraq records its driest year on record, with reserves below 4 billion cubic meters
• 2035: Projected water deficit of about 10 billion cubic meters and loss of roughly 25,000 hectares of farmland per year
Big Picture
Turkey's Southeastern Anatolia Project, with 22 dams and 19 hydroelectric plants, anchors the upstream storage expansion the study identifies as a leading cause of downstream decline. The findings place transboundary dam operations at the center of a regional water dispute that climate models alone would not explain.
Readers following water prices, food supply or regional stability should note that falling river flows threaten farmland, with roughly 25,000 hectares projected to be lost each year by 2035. Transboundary disputes over dam operations can affect commodity supply chains and humanitarian needs across the region.
The takeaway
Water security in shared river basins depends as much on upstream dam and agricultural decisions as on climate conditions. Policymakers and the public alike should weigh management choices alongside weather when assessing future scarcity.
Further reading
Explore more in Environmental for context on how human activity reshapes river systems.
Source note: This article includes information reported by Tiredearth.
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