The Tigris–Euphrates river system is a large river system in

West Asia West Asia (also called Western Asia or Southwest Asia) is the westernmost region of Asia. As defined by most academics, UN bodies and other institutions, the subregion consists of Anatolia, the Arabian Peninsula, Iran, Mesopotamia, the Armenian ...

that flows into the

Persian Gulf The Persian Gulf, sometimes called the Arabian Gulf, is a Mediterranean seas, mediterranean sea in West Asia. The body of water is an extension of the Arabian Sea and the larger Indian Ocean located between Iran and the Arabian Peninsula.Un ...

. Its primary rivers are the

Tigris The Tigris ( ; see #Etymology, below) is the eastern of the two great rivers that define Mesopotamia, the other being the Euphrates. The river flows south from the mountains of the Armenian Highlands through the Syrian Desert, Syrian and Arabia ...

and

Euphrates The Euphrates ( ; see #Etymology, below) is the longest and one of the most historically important rivers of West Asia. Tigris–Euphrates river system, Together with the Tigris, it is one of the two defining rivers of Mesopotamia (). Originati ...

, along with smaller

tributaries A tributary, or an ''affluent'', is a stream or river that flows into a larger stream ('' main stem'' or ''"parent"''), river, or a lake. A tributary does not flow directly into a sea or ocean. Tributaries, and the main stem river into which the ...

. From their sources and upper courses in the

Armenian highlands The Armenian highlands (; also known as the Armenian upland, Armenian plateau, or Armenian tableland)Robert Hewsen, Hewsen, Robert H. "The Geography of Armenia" in ''The Armenian People From Ancient to Modern Times Volume I: The Dynastic Periods: ...

of eastern

Turkey Turkey, officially the Republic of Türkiye, is a country mainly located in Anatolia in West Asia, with a relatively small part called East Thrace in Southeast Europe. It borders the Black Sea to the north; Georgia (country), Georgia, Armen ...

, being Lake Hazar for the Tigris and Karasu along with the

Murat River The Murat River, also called Eastern Euphrates (, , ), is a major source of the Euphrates River. The Ancient Greeks and Romans used to call the river ''Arsanias'' (). It originates near Mount Ararat north of Lake Van, in Eastern Turkey, and flows ...

for the Euphrates, the two rivers descend through valleys and gorges to the uplands of Syria and northern Iraq and then to the

alluvial plain An alluvial plain is a plain (an essentially flat landform) created by the deposition of sediment over a long period by one or more rivers coming from highland regions, from which alluvial soil forms. A ''floodplain'' is part of the process, bei ...

of central Iraq. Other tributaries join the Tigris from sources in the

Zagros Mountains The Zagros Mountains are a mountain range in Iran, northern Iraq, and southeastern Turkey. The mountain range has a total length of . The Zagros range begins in northwestern Iran and roughly follows Iran's western border while covering much of s ...

to the east. The rivers flow in a south-easterly direction through the central plain and combine at Al-Qurnah to form the Shatt al-Arab and discharge into the Persian Gulf. The rivers and their tributaries drain an area of , including almost the entire area of

Iraq Iraq, officially the Republic of Iraq, is a country in West Asia. It is bordered by Saudi Arabia to Iraq–Saudi Arabia border, the south, Turkey to Iraq–Turkey border, the north, Iran to Iran–Iraq border, the east, the Persian Gulf and ...

as well as portions of Turkey,

Syria Syria, officially the Syrian Arab Republic, is a country in West Asia located in the Eastern Mediterranean and the Levant. It borders the Mediterranean Sea to the west, Turkey to Syria–Turkey border, the north, Iraq to Iraq–Syria border, t ...

Iran Iran, officially the Islamic Republic of Iran (IRI) and also known as Persia, is a country in West Asia. It borders Iraq to the west, Turkey, Azerbaijan, and Armenia to the northwest, the Caspian Sea to the north, Turkmenistan to the nort ...

and

Kuwait Kuwait, officially the State of Kuwait, is a country in West Asia and the geopolitical region known as the Middle East. It is situated in the northern edge of the Arabian Peninsula at the head of the Persian Gulf, bordering Iraq to Iraq–Kuwait ...

. The region has historical importance as part of the

Fertile Crescent The Fertile Crescent () is a crescent-shaped region in the Middle East, spanning modern-day Iraq, Israel, Jordan, Lebanon, Palestine, and Syria, together with northern Kuwait, south-eastern Turkey, and western Iran. Some authors also include ...

, where

Mesopotamia Mesopotamia is a historical region of West Asia situated within the Tigris–Euphrates river system, in the northern part of the Fertile Crescent. Today, Mesopotamia is known as present-day Iraq and forms the eastern geographic boundary of ...

n civilization first emerged.

Geography

The Tigris–Euphrates Basin is shared between Turkey, Syria, Iraq, Iran, and Kuwait. Many tributaries of the Tigris river originate in Iran, and the Shatt al-Arab, formed by the

confluence In geography, a confluence (also ''conflux'') occurs where two or more watercourses join to form a single channel (geography), channel. A confluence can occur in several configurations: at the point where a tributary joins a larger river (main ...

of the Euphrates and Tigris rivers, makes up a portion of the Iran–Iraq border, with Kuwait's Bubiyan Island being part of its delta. Since the 1960s and in the 1970s, when Turkey began the GAP project in earnest, water disputes have regularly occurred in addition to the associated dam's effects on the environment. In addition, Syrian and Iranian dam construction has also contributed to political tension within the basin, particularly during drought. The

ecoregion An ecoregion (ecological region) is an ecological and geographic area that exists on multiple different levels, defined by type, quality, and quantity of environmental resources. Ecoregions cover relatively large areas of land or water, and c ...

is characterized by two large rivers, the

and

. The high mountains in the upper watershed receive more rain and snow than the lower watershed, which has a hot and arid subtropical climate. Annual snow melt from the mountains brings spring floods, and sustains permanent and seasonal marshes in the lowlands. The plain between the two rivers is known as

. As part of the larger

, it saw the earliest emergence of literate urban

civilization A civilization (also spelled civilisation in British English) is any complex society characterized by the development of state (polity), the state, social stratification, urban area, urbanization, and symbolic systems of communication beyon ...

in the

Uruk period The Uruk period (; also known as Protoliterate period) existed from the protohistory, protohistoric Chalcolithic to Early Bronze Age period in the history of Mesopotamia, after the Ubaid period and before the Jemdet Nasr period. Named after the S ...

. For this reason, it is often described as a "

Cradle of Civilization A cradle of civilization is a location and a culture where civilization was developed independent of other civilizations in other locations. A civilization is any complex society characterized by the development of the state, social strati ...

". There is a large floodplain in the lower basin where the Euphrates, Tigris, and Karun rivers converge to create the Mesopotamian Marshes, which include permanent lakes, marshes, and

riparian forest A riparian forest or riparian woodland is a forested or wooded area of land adjacent to a body of water such as a river, stream, pond, lake, marshland, estuary, canal, Sink (geography), sink, or reservoir. Due to the broad nature of the definitio ...

s. The

hydrology Hydrology () is the scientific study of the movement, distribution, and management of water on Earth and other planets, including the water cycle, water resources, and drainage basin sustainability. A practitioner of hydrology is called a hydro ...

of these vast marshes is extremely important to the ecology of the entire upper

History

Some of the first civilizations emerged from the confluence of the Tigris and Euphrates rivers. From ancient times empires arose and fell in the river basin, including

Sumer Sumer () is the earliest known civilization, located in the historical region of southern Mesopotamia (now south-central Iraq), emerging during the Chalcolithic and Early Bronze Age, early Bronze Ages between the sixth and fifth millennium BC. ...

, Akkad,

Babylonia Babylonia (; , ) was an Ancient history, ancient Akkadian language, Akkadian-speaking state and cultural area based in the city of Babylon in central-southern Mesopotamia (present-day Iraq and parts of Kuwait, Syria and Iran). It emerged as a ...

Assyria Assyria (Neo-Assyrian cuneiform: , ''māt Aššur'') was a major ancient Mesopotamian civilization that existed as a city-state from the 21st century BC to the 14th century BC and eventually expanded into an empire from the 14th century BC t ...

, and the

Abbasid Caliphate The Abbasid Caliphate or Abbasid Empire (; ) was the third caliphate to succeed the Islamic prophet Muhammad. It was founded by a dynasty descended from Muhammad's uncle, Abbas ibn Abd al-Muttalib (566–653 CE), from whom the dynasty takes ...

. Being part of the

, the river system is recognized as the site of one of the world's first agricultural centers, with archeological sites containing preserved grain dating up to 12,500 years ago. The river system was used by major cities including Ur and Babylon to promote trade and the sharing of cultures. As a result of its invention of the qanat system thousands of years ago which uses gravity to transport water through subterranean tunnels, Iran has a history as an agricultural nation, despite its aridity.

Ecology

The most abundant fishes are species of barbs ('' Barbus''), some of which can reach up to two meters in length. Some species have been important food sources for residents for thousands of years. Specifically, the Mangar fish has been harvested for food in the Tigris-Euphrates basin. Many species move seasonally between the river and the marshes for spawning, feeding, and overwintering. The Hilsa shad (''Tenualosa ilisha'') is an important food fish that lives in the coastal waters and spawns in the lower reaches of the basin. Other ocean species occasionally visit the lower reaches of the rivers; bull sharks (''Carcharhinus leucas'') used to swim up the Tigris as far as Baghdad."Lower Tigris & Euphrates". ''Freshwater Ecoregions of the World''. Accessed 30 June 2020

/ref> Endemism, Endemic fish species in the lower basin include '' Glyptothorax steindachneri'' and '' Hemigrammocapoeta elegans'', and as well as two cave fishes, '' Caecocypris basimi'' and the Iraq blind barb (''Typhlogarra widdowsoni''), from a cave habitat near Haditha on the Euphrates. One-third of the fish species in the upper watersheds are endemic, including species of '' Aphanius, Glyptothorax, Cobitis, Orthrias'', and '' Schistura''. Two blind fish species, the Iran cave barb (''Iranocypris typhlops'') and the Zagros blind loach (''Eidinemacheilus smithi''), are endemic to cave systems in Iran's upper Karun River watershed."Upper Tigris & Euphrates". ''Freshwater Ecoregions of the World''. Accessed 30 June 2020

/ref> The Batman River loach (''Paraschistura chrysicristinae'') is a

Critically Endangered An IUCN Red List critically endangered (CR or sometimes CE) species is one that has been categorized by the International Union for Conservation of Nature as facing an extremely high risk of extinction in the wild. As of December 2023, of t ...

fish species endemic to the

Batman Batman is a superhero who appears in American comic books published by DC Comics. Batman was created by the artist Bob Kane and writer Bill Finger, and debuted in Detective Comics 27, the 27th issue of the comic book ''Detective Comics'' on M ...

and Ambar rivers, Turkish tributaries of the Tigris. The species is endangered by drought,

habitat destruction Habitat destruction (also termed habitat loss or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease ...

, and

habitat fragmentation Habitat fragmentation describes the emergence of discontinuities (fragmentation) in an organism's preferred environment (habitat), causing population fragmentation and ecosystem decay. Causes of habitat fragmentation include geological proces ...

from the construction of the Batman Dam. It had not been observed since 1974 and was feared extinct until a 2021 expedition netted 14 fish living above the Batman Dam.Greene, Graeme (2021) "Batman loach returns: fish feared extinct found in Turkey". ''The Guardian'' 9 December 2021

/ref>

Mesopotamian Marshes

The Mesopotamian Marshes in southern Iraq were historically the largest wetland

ecosystem An ecosystem (or ecological system) is a system formed by Organism, organisms in interaction with their Biophysical environment, environment. The Biotic material, biotic and abiotic components are linked together through nutrient cycles and en ...

of Western

Eurasia Eurasia ( , ) is a continental area on Earth, comprising all of Europe and Asia. According to some geographers, Physical geography, physiographically, Eurasia is a single supercontinent. The concept of Europe and Asia as distinct continents d ...

. The aquatic vegetation includes reeds, rushes, and

papyrus Papyrus ( ) is a material similar to thick paper that was used in ancient times as a writing surface. It was made from the pith of the papyrus plant, ''Cyperus papyrus'', a wetland sedge. ''Papyrus'' (plural: ''papyri'' or ''papyruses'') can a ...

, which support numerous species. Areas around the Tigris and the Euphrates are very fertile. Marshy land is home to water birds, some stopping here while migrating, and some spending the winter in these marshes living off the lizards, snakes, frogs, and fish. Other animals found in these marshes are

water buffalo The water buffalo (''Bubalus bubalis''), also called domestic water buffalo, Asian water buffalo and Asiatic water buffalo, is a large bovid originating in the Indian subcontinent and Southeast Asia. Today, it is also kept in Italy, the Balkans ...

, two

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

rodent Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and Mandible, lower jaws. About 40% of all mammal specie ...

species,

antelope The term antelope refers to numerous extant or recently extinct species of the ruminant artiodactyl family Bovidae that are indigenous to most of Africa, India, the Middle East, Central Asia, and a small area of Eastern Europe. Antelopes do ...

s and

gazelle A gazelle is one of many antelope species in the genus ''Gazella'' . There are also seven species included in two further genera; '' Eudorcas'' and '' Nanger'', which were formerly considered subgenera of ''Gazella''. A third former subgenus, ' ...

s and small animals such as the jerboa and several other mammals. The wetland birds Basra reed warbler (''Acrocephalus griseldis'') and Iraq babbler (''Argya altirostris'') are endemic to the Mesopotamian Marshes. The Basra reed warbler is endangered. Another wetland endemic species, Bunn's short-tailed bandicoot rat (''Nesokia bunnii''), is possibly extinct. Their drainage began in the 1950s, to reclaim land for agriculture and oil exploration.

Saddam Hussein Saddam Hussein (28 April 1937 – 30 December 2006) was an Iraqi politician and revolutionary who served as the fifth president of Iraq from 1979 until Saddam Hussein statue destruction, his overthrow in 2003 during the 2003 invasion of Ira ...

extended this work in the late 1980s and early 1990s, as part of ecological warfare against the Marsh Arabs, a rebellious group of people in Baathist Iraq. However, with the breaching of the dikes by local communities after the 2003 invasion of Iraq and the ending of a four-year drought that same year, the process has been reversed and the marshes have experienced a substantial rate of recovery. The permanent wetlands now cover more than 50% of pre-1970s levels, with a remarkable regrowth of the Hammar and Hawizeh Marshes and some recovery of the Central Marshes.

Ecological threats

Iraq suffers from

desertification Desertification is a type of gradual land degradation of Soil fertility, fertile land into arid desert due to a combination of natural processes and human activities. The immediate cause of desertification is the loss of most vegetation. This i ...

and soil salination due in large part to thousands of years of agricultural activity. Water and plant life are sparse.

's government water-control projects drained the inhabited marsh areas east of An Nasiriyah by drying up or diverting streams and rivers. Shi'a Muslims were displaced under the

Ba'athist Ba'athism, also spelled Baathism, is an Arab nationalist ideology which advocates the establishment of a unified Arab state through the rule of a Ba'athist vanguard party operating under a revolutionary socialist framework. The ideology ...

regime. The destruction of the natural habitat poses serious threats to the area's

wildlife Wildlife refers to domestication, undomesticated animals and uncultivated plant species which can exist in their natural habitat, but has come to include all organisms that grow or live wilderness, wild in an area without being species, introdu ...

populations. There are also inadequate supplies of potable water. The

marshland In ecology, a marsh is a wetland that is dominated by herbaceous plants rather than by woody plants.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p More in general ...

s were an extensive natural wetland

, which developed over thousands of years in the Tigris–Euphrates basin and once covered 15–20,000 square kilometers. In the 1980s, this ecoregion was put in grave danger during the

Iran–Iraq War The Iran–Iraq War, also known as the First Gulf War, was an armed conflict between Iran and Iraq that lasted from September 1980 to August 1988. Active hostilities began with the Iraqi invasion of Iran and lasted for nearly eight years, unti ...

. After the 1991

Gulf War , combatant2 = , commander1 = , commander2 = , strength1 = Over 950,000 soldiers3,113 tanks1,800 aircraft2,200 artillery systems , page = https://www.govinfo.gov/content/pkg/GAOREPORTS-PEMD-96- ...

, Iraq's President

initiated a drainage project on these marshes, leading to degradation of ecosystem services that caused economic and social issues for civilians. The Mesopotamian Marshes, which were inhabited by the Marsh Arabs, were almost completely drained. Although they had started to recover after the fall of

Ba'athist Iraq Ba'athist Iraq, officially the Iraqi Republic (1968–1992) and later the Republic of Iraq (1992–2003), was the Iraqi state between 1968 and 2003 under the one-party rule of the Arab Socialist Ba'ath Party – Iraq Region, Iraqi regional bra ...

in 2003, drought, intensive dam construction and irrigation schemes upstream have caused them to dry up once more. According to the United Nations Environmental Program and the AMAR Charitable Foundation, between 84% and 90% of the marshes have been destroyed since the 1970s. In 1994, 60 percent of the wetlands were destroyed by Hussein's regime – drained to permit military access and greater political control of the native Marsh Arabs. Canals, dykes and dams were built routing the water of the Tigris and Euphrates Rivers around the marshes, instead of allowing water to move slowly through the marshland. After part of the Euphrates was dried up due to re-routing its water to the sea, a dam was built so water could not back up from the Tigris and sustain the former marshland. Some marshlands were burned and pipes buried underground helped to carry away water for quicker drying. Riparian entities have constructed dams along the Tigris–Euphrates river system as a method of water management in response to droughts. Turkey, for example, is in control of an estimated 45% of the system's water sources due to its dam constructions for water quantity and hydroelectric power. The drying of the marshes led to the disappearance of the salt-tolerant vegetation; the

plankton Plankton are the diverse collection of organisms that drift in Hydrosphere, water (or atmosphere, air) but are unable to actively propel themselves against ocean current, currents (or wind). The individual organisms constituting plankton are ca ...

rich waters that fertilized surrounding soils; 52 native fish species; the

wild boar The wild boar (''Sus scrofa''), also known as the wild swine, common wild pig, Eurasian wild pig, or simply wild pig, is a Suidae, suid native to much of Eurasia and North Africa, and has been introduced to the Americas and Oceania. The speci ...

red fox The red fox (''Vulpes vulpes'') is the largest of the true foxes and one of the most widely distributed members of the order Carnivora, being present across the entire Northern Hemisphere including most of North America, Europe and Asia, plus ...

, buffalo and

water bird A water bird, alternatively waterbird or aquatic bird, is a bird that lives on or around water. In some definitions, the term ''water bird'' is especially applied to birds in freshwater ecosystems, although others make no distinction from seabi ...

s of the marsh habitat. Climate change also affects the environmental and social well-being. Climate change and human interaction have directly impacted the Tigris–Euphrates river system, leading to a negative trend in water storage capabilities in the river basin. The combination of diminishing water levels in the Tigris–Euphrates river system and rising sea levels indicates the potential for rapid seawater intrusion in the river basin. This is especially concerning as the demand for clean water increases while the water supply decreases. Currently, the Middle East and North Africa are acknowledged as the most water scarce region in the world, with 61% of the population living in areas with high or very high water stress. As climate change worsens and population grows, water scarcity in the region is expected to worsen with 100% of people living in the Middle East and North Africa living in areas with high water stress by 2050.

Water dispute

The issue of water rights became a point of contention for Iraq, Turkey and Syria beginning in the 1960s when Turkey implemented a public-works project (the GAP project) aimed at harvesting the water from the Tigris and Euphrates rivers through the construction of 22 dams, for

irrigation Irrigation (also referred to as watering of plants) is the practice of applying controlled amounts of water to land to help grow crops, landscape plants, and lawns. Irrigation has been a key aspect of agriculture for over 5,000 years and has bee ...

and hydroelectric energy purposes. Although the water dispute between Turkey and Syria was more problematic, the GAP project was also perceived as a threat by Iraq. In 1983, the Joint Technical Committee (JTC) was established to solve ongoing data controversies between Turkey, Syria, and Iraq but stopped meeting in the early 1990s after only passing two bilateral agreements. The tension between Turkey and Iraq about the issue was increased by the effect of Syria and Turkey's participation in the UN embargo against Iraq following the

. However, the issue had never become as significant as the water dispute between Turkey and Syria. The 2008 drought in Iraq sparked new negotiations between Iraq and Turkey over trans-boundary river flows. Although the drought affected Turkey, Syria and Iran as well, Iraq complained regularly about reduced water flows. Iraq particularly complained about the Euphrates River because of the large number of dams on the river. Turkey agreed to increase the flow several times, beyond its means in order to supply Iraq with water. Iraq has seen significant declines in water storage and crop yields because of the drought. To make matters worse, Iraq's water infrastructure has suffered from years of conflict and neglect. In 2008, Turkey, Iraq and Syria agreed to restart the Joint Trilateral Committee on water for the three nations for better water resources management. Turkey, Iraq and Syria signed a memorandum of understanding on September 3, 2009, in order to strengthen communication within the Tigris–Euphrates Basin and to develop joint water-flow-monitoring stations. On September 19, 2009, Turkey formally agreed to increase the flow of the Euphrates River to 450 to 500 m³/s, but only until October 20, 2009. In exchange, Iraq agreed to trade petroleum with Turkey and help curb

Kurd Kurds (), or the Kurdish people, are an Iranian peoples, Iranic ethnic group from West Asia. They are indigenous to Kurdistan, which is a geographic region spanning southeastern Turkey, northwestern Iran, northern Iraq, and northeastern Syri ...

ish militant activity in their border region. One of Turkey's last large GAP dams on the Tigris – the Ilisu Dam – is strongly opposed by Iraq and is the source of political strife. The

Southeastern Anatolia Project The Southeastern Anatolia Project (, GAP) is a multi-sector integrated regional development project based on the concept of sustainable development for the 9 million people (2023) living in the Southeastern Anatolia Region, Turkey, Southeastern An ...

(Turkish acronym: GAP) continues to be a source of tension in the region. GAP is a massive hydroelectric project, consisting of 21 dams and 19 hydroelectric facilities. In 2020, Iraqi authorities complained that the Ilısu Dam had decreased the Tigris river inflows and caused water shortages in Iraqi plains.

In media

* '' Dawn of the World'', film, 2008. * ''Zaman, The Man From The Reeds'', film, 2003

References

External links

Persian Gulf image

BBC: Iraq marshes' recovery 'in doubt'
{{DEFAULTSORT:Tigris-Euphrates River System . . Drainage basins of Asia Ecoregions of Asia Ecoregions of Iran Ecoregions of Iraq Ecoregions of Syria Ecoregions of Turkey Geography of Kuwait Freshwater ecoregions Palearctic ecoregions Articles containing video clips