The Euphrates (Firat or Furat as it is called in Turkey) is an international river shared by Turkey, Syria and Iraq. The Tigris (Dicle as it is called in Turkey and Digla in Iraq) is an international river basin shared by Turkey, Iraq and Iran, with Syria as a minor riparian. The Euphrates and the Tigris have almost completely separate basins which unify only in their last 190 km at the Shatt al-Arab; but as Iraq, Syria and Turkey share both rivers, it is customary to treat the two separate basins as one unit.
Table 2.1 presents the length of the Euphrates and Tigris and their tributaries and describes international participation in the main channel of the Euphrates 3,000 km long, which is shared by Iraq (36 per cent), Syria (23 per cent) and Turkey (41 per cent). Syria also has almost total control over the springs of the Khabour and Balikh, and controls some 70 per cent of their drainage basins. The Tigris is only 1,850 km long and most of it (77 per cent) is in Iraq followed by Turkey (22 per cent) and Syria which has 44 km in the main river channel (and a small tributary), constituting its border with Turkey (about 36 km) and with Iraq (about 8 km). Iran becomes a partner in the Tigris basin because of its part in the Lesser Zab and Diyalah, both important tributaries to the Tigris, and Iran also contains the Kharun which discharges its waters into the Shatt al-Arab. The Shatt al-Arab is unequally shared by Iran and Iraq and it constitutes the border between the two.
The Tigris-Euphrates system has the following particular hydro-political features. First, the two rivers are shared by Turkey, Syria and Iraq. Equitable allocation of their waters can take advantage of this fact by apportioning the waters of the Euphrates to one riparian while the waters of the Tigris and its tributaries can be allocated to other riparians. Second, the relations between Syria and Turkey and Syria and Iraq have gone through moments of crisis and tension in the past, a fact which poses difficulties for the readiness of the co-riparians to negotiate agreements in a spirit of trust. Third, Iraq, like Egypt, has possessed ancient rights to the Tigris-Euphrates waters for 6,000 years being