Upstream, Downstream: The Politics of Water in the Tigris–Euphrates Basin

The Tigris and the Euphrates rise in the mountains of eastern Turkey, cross or skirt Syria, and flow through Iraq until they meet at al-Qurna to form the Shatt al-Arab. For millennia they sustained the agriculture of Mesopotamia. Today they sustain one of the region’s most persistent — if least violent — international disputes.

Geography sets the terms#

In any shared river basin, the upstream state holds the physical advantage. Turkey provides the great majority of the Euphrates’ flow and a large share of the Tigris’. Syria is both downstream of Turkey and upstream of Iraq on the Euphrates. Iraq, at the end of both rivers, is the most exposed: what arrives at its borders depends on decisions made in Ankara and Damascus.

That asymmetry would matter less if water were plentiful. It is not. Rising demand for irrigation and electricity, recurrent droughts, and rising temperatures have all made the flow of the rivers a question of national security.

Dams and development#

Since the 1960s, all three states have built dams to store water, irrigate land and generate power. The largest programme by far is Turkey’s Southeastern Anatolia Project (GAP), a regional development scheme that envisaged 22 dams and 19 hydroelectric plants on the two rivers.

Its centrepiece, the Atatürk Dam on the Euphrates, was completed in 1990. When Turkey began filling its reservoir that January, it reduced the river’s flow into Syria for about a month — an episode that alarmed Damascus and Baghdad and demonstrated the leverage the dams provided. On the Tigris, the Ilısu Dam began impounding water in 2019, submerging the ancient town of Hasankeyf and raising new concerns in Iraq.

A near-war in 1975#

Water has come close to provoking armed conflict. In 1975, as Syria filled the reservoir behind its Tabqa Dam and Turkey filled Keban, the flow reaching Iraq fell sharply. Baghdad accused Damascus of endangering its farmers, both sides moved troops towards the border, and the crisis was defused only through outside mediation, including by Saudi Arabia.

Agreements without a regime#

The basin is governed by a patchwork of partial arrangements rather than a comprehensive treaty:

• A 1987 protocol between Turkey and Syria, in which Turkey undertook to release an average of 500 cubic metres per second of Euphrates water at the Syrian border.
• An agreement between Syria and Iraq, concluded at the end of the 1980s, dividing the Euphrates flow entering Syria at roughly 58 per cent for Iraq and 42 per cent for Syria.
• Various joint technical committees and memoranda, which have met intermittently and produced little binding commitment.

None of these arrangements covers the whole basin, and none reflects a shared understanding of how water should be allocated. Turkey has tended to emphasise its sovereign rights over resources originating on its territory and the “optimal utilisation” of water, while Syria and Iraq appeal to principles of equitable use and acquired rights. Turkey was one of only three states to vote against the 1997 UN Convention on the Law of the Non-Navigational Uses of International Watercourses.

Scarcity explains why water matters. Power explains who gets it.

Hydro-hegemony#

A useful framework for understanding the basin is the concept of hydro-hegemony, developed by Mark Zeitoun and Jeroen Warner. It argues that outcomes in shared basins reflect not only geography but also material power, bargaining power and the ability to shape the terms of debate. By this measure Turkey is the basin’s hegemon — upstream, economically stronger and able to present its dams as instruments of development and regional cooperation.

Hegemony, however, is not simply domination. Turkey has also used water as a diplomatic tool, offering releases or cooperation at moments of improved relations with Iraq. The question for the future is whether such ad hoc gestures can become a durable framework.

Looking ahead#

Climate projections for the region point to higher temperatures, more variable rainfall and longer droughts. Combined with population growth and inefficient irrigation, these trends will make the absence of a basin-wide agreement increasingly costly — above all for Iraq. Water politics in Mesopotamia are unlikely to produce war. They are very likely to shape the prosperity, stability and migration patterns of the region for decades to come.