Tigris–Euphrates river system Tigris–Euphrates river system The Tigris and Euphrates, with their tributaries, form a major river system in Western Asia. From sources originating in eastern Turkey, they flow by/through Syria through Iraq into the Persian Gulf. The system is part of the Palearctic Tigris–Euphrates ecoregion, which includes Iraq and parts of Turkey, Syria, Iran, Saudi Arabia, Kuwait, and Jordan. From their sources and upper courses in the mountains of eastern Anatolia, the rivers descend through valleys and gorges to the uplands of Syria and northern Iraq and then to the alluvial plain of central Iraq. The rivers flow in a south-easterly direction
Euphrates discharge at Hīt after 1990 has dropped to per second ( per year). The seasonal variability has equally changed. The pre-1990 peak volume recorded at Hīt was per second, while after 1990 it is only per second. The minimum volume at Hīt remained relatively unchanged, rising from per second before 1990 to per second afterward. In Syria, three rivers add their water to the Euphrates; the Sajur, the Balikh and the Khabur. These rivers rise in the foothills of the Taurus Mountains along the Syro–Turkish border and add comparatively little water to the Euphrates. The Sajur is the smallest of