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(tī`grĭs), river of SW Asia, c.1,150 mi (1,850 km) long, rising in the Taurus Mts., E Turkey, and flowing SE through Iraq to join the Euphrates River, with which it forms the Shatt al ArabShatt al Arab
, tidal river, 120 mi (193 km) long, formed by the confluence of the Tigris and Euphrates rivers, flowing SE to the Persian Gulf, forming part of the Iraq-Iran border; the Karun is its chief tributary.
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. It flows swiftly and receives many tributaries, including the Diyala, originating in the Zagros Mts., and the Great and Little Zab. The lower Tigris is connected to the Euphrates by semipermanent natural channels and by ancient canals. Much of the marshland along the lower Tigris was drained in the early 1990s; restoration began in 2003. Dams across the river divert water for irrigation.

The Tigris is subject to sudden, devastating floods, and the Wadi Ath Tharthar Scheme, Iraq's largest flood-control project, protects Baghdad and vicinity from floods in addition to irrigating c.770,000 acres (311,600 hectares) of land. Since the 1990s a series of dams has been constructed on the Tigris and Euphrates in Turkey. The plans for the Southeast Anatolia Project ultimately call for 22 dams that altogether will provide water to irrigate more than 3,700,000 acres (1.5 million hectares) of land. A series of hydroelectric power stations is also being built; by 2014 more than half the dams had been completed. It is unclear to what degree the dams and irrigation may cause problems in countries downstream that rely on the river's resources.

The Tigris is navigable to Baghdad for shallow-draft vessels; above Baghdad, rafts carry much of the trade to Mosul. Its importance as a trade artery has declined with improved road and rail connections. BasraBasra
, Arabic al Basrah, city (1987 pop. 406,296), SE Iraq, on the Shatt al Arab. Basra is Iraq's second largest city and principal port. Its commercially advantageous location, near oil fields and 75 mi (121 km) from the Persian Gulf, has made it prosperous, and oil is
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, at the junction of the Tigris and Euphrates, is Iraq's chief port.

In antiquity, some of the great cities of Mesopotamia, including NinevehNineveh
, ancient city, capital of the Assyrian Empire, on the Tigris River opposite the site of modern Mosul, Iraq. A shaft dug at Nineveh has yielded a pottery sequence that can be equated with the earliest cultural development in N Mesopotamia.
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, CtesiphonCtesiphon
, ruined ancient city, 20 mi (32 km) SE of Baghdad, Iraq, on the left bank of the Tigris opposite Seleucia and at the mouth of the Diyala River. After 129 B.C. it was the winter residence of the Parthian kings. Ctesiphon grew rapidly and was of renowned splendor.
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, and SeleuciaSeleucia
, ancient city of Mesopotamia, on the Tigris below modern Baghdad. Founded (c.312 B.C.) by Seleucus I, it soon replaced Babylon as the main center for east-west commerce through the valley.
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, stood on the banks of the Tigris, and the river served as an important transportation route. The Tigris floodplain was cultivated by irrigation from the earliest times; the Sumerians dug a canal from the Tigris to LagashLagash
or Shirpurla
, ancient city of Sumer, S Mesopotamia, now located at Telloh, SE Iraq. Lagash was flourishing by c.2400 B.C., but traces of habitation go back at least to the 4th millennium B.C. After the fall of Akkad (2180 B.C.
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 c.2400 B.C. The Tigris is called the Hiddekil in the Bible.



a river in Turkey and Iraq, part of which flows along the border of these countries with Syria. The Tigris measures approximately 1,900 km in length and drains an area of 375,000 sq km. It originates in the eastern Taurus Mountains of eastern Turkey and flows across the Jazira Plateau and a considerable part of the Mesopotamian Lowland. Near the city of Al-Qurnah, Iraq, it joins the Euphrates River to form the Shatt al-Arab River, which empties into the Persian Gulf. The Tigris has four major tributaries, all on the left: the Great Zab, Little Zab, Diyala, and the Karkheh, which reaches the Tigris during high water.

The Tigris is fed by rain and snow. High water occurs in spring, and the maximum flow rate is in April. Catastrophic floods occur as the water of the Tigris and its tributaries rises on the Mesopotamian Lowland. As a defense against the floods, the Tigris’ channel is fortified for much of its course; some floodwater flows through a canal into Lake Thirthar, northwest of Baghdad and between the Tigris and Euphrates. Rising floodwater also endangers Baghdad. To relieve this danger, Soviet specialists in 1976 helped build the Thirthar-Euphrates Canal, which measures 37 km in length and is capable of diverting 1,100 cu m of water per sec. The Tigris reaches its maximum discharge in its middle course. The mean flow rate at Baghdad is 1,240 cu m per sec; the maximum flow rate is about 13,000 cu m per sec. In the lower course the discharge is less, since some water is used for irrigation and some flows into swamps near the river. An oasis extends along the river’s middle and lower courses.

The flow of the Tigris is regulated by dams located near the population centers of Summara, Samarra, and Al-Kut, all in Iraq. The river is navigable for vessels with a draft of up to 1.2 m as far as Baghdad, and during high water as far as Mosul. The cities of Diyarbakir in Turkey and Mosul, Baghdad, Al-Kut, and Al-Amarah in Iraq are situated on its banks.

The region between the Tigris and the Euphrates is one of the most ancient centers of civilization on earth.


Muranov, A. P. Reki Evfrat i Tigr. Leningrad, 1959.



a river in SW Asia, rising in E Turkey and flowing southeast through Baghdad to the Euphrates in SE Iraq, forming the delta of the Shatt-al-Arab, which flows into the Persian Gulf: part of a canal and irrigation system as early as 2400 bc, with many ancient cities (including Nineveh) on its banks. Length: 1900 km (1180 miles)