Editing Geography of Iraq (section)

==Tigris–Euphrates river system==
{{main|Tigris–Euphrates river system}}
[[File:Mosul Dam Lake 2019.jpg|thumb|381x381px|[[Mosul Dam]]]]
The Euphrates originates in Turkey, is augmented by the [[Balikh River|Balikh]] and [[Khabur (Euphrates)|Khabur]] rivers in Syria, and enters Iraq in the northwest. Here it is fed only by the wadis of the western desert during the winter rains. It then winds through a gorge, which varies from two to 16 kilometers in width, until it flows out on the plain at [[Ar Ramadi]]. Beyond there the Euphrates continues to the [[Hindiya Barrage]], which was constructed in 1914 to divert the river into the Hindiyah Channel; the present day Shatt al Hillah had been the main channel of the Euphrates before 1914. Below [[Al Kifl]], the river follows two channels to [[As-Samawah]], where it reappears as a single channel to join the Tigris at [[Al Qurnah]].
The Tigris also rises in Turkey but is significantly augmented by several rivers in Iraq, the most important of which are the [[Khabur (Tigris)|Khabur]], the [[Great Zab]], the [[Little Zab]], and the [[Adhaim]], all of which join the Tigris above Baghdad, and the [[Diyala River|Diyala]], which joins it about thirty-six kilometers below the city. At the [[Kut Barrage]] much of the water is diverted into the [[Shatt al-Hayy]], which was once the main channel of the Tigris. Water from the Tigris thus enters the Euphrates through the Shatt al-Hayy well above the confluence of the two main channels at Al Qurnah.

Both the Tigris and the Euphrates break into a number of channels in the marshland area, and the flow of the rivers is substantially reduced by the time they come together at Al Qurnah. Moreover. the swamps act as silt traps, and the Shatt al Arab is relatively silt free as it flows south. Below [[Basra]], however, the [[Karun River]] enters the [[Shatt al Arab]] from Iran, carrying large quantities of silt that present a continuous dredging problem in maintaining a channel for ocean-going vessels to reach the port at Basra. This problem has been superseded by a greater obstacle to river traffic, however, namely the presence of several sunken hulls that have been rusting in the Shatt al Arab since early in the Iran-Iraq war.

The waters of the Tigris and Euphrates are essential to the life of the country, but they sometimes threaten it. The rivers are at their lowest level in September and October and at flood in March, April, and May when they may carry forty times as much water as at low mark. Moreover, one season's flood may be ten or more times as great as that in another year. In 1954, for example, Baghdad was seriously threatened, and [[Dyke (construction)|dikes]] protecting it were nearly topped by the flooding Tigris. Since Syria built a dam on the Euphrates, the flow of water has been considerably diminished and flooding was no longer a problem in the mid-1980s. In 1988 Turkey was also constructing a dam on the Euphrates that would further restrict the water flow.
{{multiple image
 | total_width = 600
 | image1 = MAP THE TIGRIS FROM KUT AL AMARA TO BAGHDAD.jpg
 | alt1 = Yellow cartouche
 | image2 = RIVER TIGRIS BETWEEN ALI GHARBI AND SHUMRAN.jpg
 | alt2 = Red cartouche
 | footer = A stretch of the Tigris from [[Baghdad]] to [[Kut-al-Amara]] and from Shumran bend to Ali Gharbi.
}}
Until the mid-twentieth century, most efforts to control the waters were primarily concerned with irrigation. Some attention was given to problems of flood control and drainage before the revolution of July 14, 1958, but development plans in the 1960s and 1970s were increasingly devoted to these matters, as well as to irrigation projects on the upper reaches of the Tigris and Euphrates and the tributaries of the Tigris in the northeast. During the war, government officials stressed to foreign visitors that, with the conclusion of a peace settlement, problems of irrigation and flooding would receive top priority from the government.

Iraqi [[coastal waters]] boast a living [[coral reef]], covering an area of 28&nbsp;km<sup>2</sup> in the [[Persian Gulf]], at the mouth of the [[Shatt al-Arab]] river ({{Coord|29|37|00|N|48|48|00|E|display=inline}}).<ref name="sr">{{cite journal |author1=Thomas Pohl |author2=Sameh W. Al-Muqdadi |author3=Malik H. Ali |author4=Nadia Al-Mudaffar Fawzi |author5=Hermann Ehrlich |author6=Broder Merkel |title =Discovery of a living coral reef in the coastal waters of Iraq |journal =[[Scientific Reports]]|volume=4 |pages=4250 |doi=10.1038/srep04250|pmid=24603901 |date=6 March 2014|pmc=3945051 }}</ref> The coral reef was discovered by joint Iraqi–German expeditions of scientific scuba divers carried out in September 2012 and in May 2013.<ref name="sr"/> Prior to its discovery, it was believed that Iraq lacks coral reefs as the local turbid waters prevented the detection of the potential presence of local coral reefs. Iraqi corals were found to be adapted to one of the most extreme coral-bearing environments in the world, as the seawater temperature in this area ranges between 14 and 34&nbsp;°C.<ref name="sr"/> The reef harbors several living stone corals, [[octocorals]], [[ophiuroids]] and [[bivalves]].<ref name="sr"/> There are also [[silica]]-containing demo-sponges.<ref name="sr"/>