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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.

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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



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.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


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)
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
The headwaters of Iraq's two main rivers, the Tigris and the Euphrates, originate in the eastern Turkish highlands.
Baghdad's river today is a stew of industrial chemicals, untreated sewage and poisonous agricultural runoff, the Save the Tigris civil society campaign said in a 2018 report.
The volume of the Tigris in Iraq has dropped by eight billion cubic metres since last year, clocking in at 17 billion cubic metres as the scorching summer sets in.
The Tigris River is the second largest river in Western Asia.
And for JP McManus, Tigris River was a second Galway Hurdle winner, the owner having had seven runners in all this year.
"We, the undersigned, call on the United Nations and UNESCO to respond to the worrying situation of indigenous peoples and their water rights on the Tigris and Euphrates river basin.
The Gore Tigris device, which gained CE Mark approval in 2011, is a third generation, self-expanding stent.
Iranian forces seized the MV Maersk Tigris on April 28 after firing warning shots across its bridge as it traversed the
"We are continuing our efforts to obtain more information about the Iranian authorities' seizure -- in international waters -- of Maersk Tigris. We are not able at this point to establish or confirm the reason behind the seizure."
The CMA CGM TIGRIS will be a chartered bareboat sailing under the Malta flag and the result of collaboration between the Chinese shipyards NTS (New Times Shipbuildings Jiangsu Province People's Republic of China) CIMC group and the CMA CGM Group experts.
The Energy Market Regulatory Agency (EPDK) recently approved three hydroelectric power plant projects to be constructed jointly by the Ministry of Environment and Urban Planning and the State Waterworks Authority (DSy) on the Tigris River.