Executive Summary 

The Shatt al Arab River is formed by the confluence of the Euphrates and Tigris Rivers near the city of Qurnah in southern Iraq. Downstream of Qurnah, the area draining to the Shatt al Arab region is shared between Iran and Iraq. In addition to the Euphrates and Tigris Rivers, the Karkheh and the Karun sub-basins contribute water to the Shatt al Arab. Both the Karkheh and the Karun Rivers originate in the Zagros Mountains in Iran and discharge into the Shatt al Arab.

The Shatt al Arab River forms the main source of freshwater for the Persian Gulf and plays an important role for marine habitats in the Gulf's north-eastern coastal areas. However, the large-scale development of upstream water regulation and dam structures, together with the drainage of the Mesopotamian Marshes have caused severe salinization of the river. This not only threatens marine ecosystems in the Gulf, but also jeopardizes agricultural activity along the Shatt al Arab.

There are no water agreements in place for the Shatt al Arab, Karun or Karkheh Rivers. However, Iran and Iraq have agreed to cooperate on issues of common concern.

Key Concerns 

Water Quantity

Intensive water resource development (mainly dams and irrigation infrastructure) in the upstream areas of the Euphrates and Tigris Basins has resulted in a reduction of flows to the Shatt al Arab River and Mesopotamian Marshes.
Iraq has voiced concern over recent Iranian plans to construct a levy along the Iran-Iraq border through the Haweizeh Marshes. Such a levy would reduce freshwater flow to Iraq, further threatening the marsh ecosystems.

Water Quality

The drainage of the Mesopotamian Marshes has had a negative impact on the Shatt al Arab and the Persian Gulf: the increase in salinity levels in the Shatt al Arab has caused noticeable degradation of coastal areas in Kuwait due to the presence of toxic sediments in the Gulf. Increased pollution from agricultural, industrial and domestic effluents forms an additional problem.

  • The Shatt al Arab, Iraq, 1992. Source: Ed Kashi/VII.
  • The Karun-3 Dam on the Karun River, Iran, 2008. Source: M. Samadi.
  • The Shatt al Arab, Iraq, 1992. Source: Ed Kashi/VII.

Basin Facts 

River Shatt al Arab River Karkheh River Basin Karun River Basin
Riparian Countries Iran, Iraq Iran, Iraq --
Basin Area Shares -- Iran, Iraq Iran
Basin Area -- 51,110 km2 71,980 km2
River Length 192 km 964 km 867 km
Mean Annual Flow Volume -- 5.8 BCM 24.5 BCM
Dams -- 2 (max. storage capacity 7.9 BCM) 6 (max. storage capacity 12.4 BCM)
Projected Irrigated Area -- -- --
Basin Population -- 4 million 3.5 million