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Iraq
Index
Figure 5. Topography and Drainage
Most geographers, including those of the Iraqi government,
discuss the country's geography in terms of four main zones or
regions: the desert in the west and southwest; the rolling upland
between the upper Tigris and Euphrates rivers (in Arabic the
Dijlis and Furat, respectively); the highlands in the north and
northeast; and the alluvial plain through which the Tigris and
Euphrates flow
(see fig.5). Iraq's official statistical reports
give the total land area as 438,446 square kilometers, whereas a
United States Department of State publication gives the area as
434,934 square kilometers.
The desert zone, an area lying west and southwest of the
Euphrates River, is a part of the Syrian Desert, which covers
sections of Syria, Jordan, and Saudi Arabia. The region, sparsely
inhabited by pastoral nomads, consists of a wide, stony plain
interspersed with rare sandy stretches. A widely ramified pattern
of wadis--watercourses that are dry most of the year--runs from
the border to the Euphrates. Some Wadis are over 400 kilometers
long and carry brief but torrential floods during the winter
rains.
The uplands region, between the Tigris north of Samarra and
the Euphrates north of Hit, is known as Al Jazirah (the island)
and is part of a larger area that extends westward into Syria
between the two rivers and into Turkey. Water in the area flows
in deeply cut valleys, and irrigation is much more difficult than
it is in the lower plain. Much of this zone may be classified as
desert.
The northeastern highlands begin just south of a line drawn
from Mosul to Kirkuk and extend to the borders with Turkey and
Iran. High ground, separated by broad, undulating steppes, gives
way to mountains ranging from 1,000 to nearly 4,000 meters near
the Iranian and Turkish borders. Except for a few valleys, the
mountain area proper is suitable only for grazing in the
foothills and steppes; adequate soil and rainfall, however, make
cultivation possible. Here, too, are the great oil fields near
Mosul and Kirkuk. The northeast is the homeland of most Iraqi
Kurds.
The alluvial plain begins north of Baghdad and extends to the
Persian Gulf. Here the Tigris and Euphrates rivers lie above the
level of the plain in many places, and the whole area is a delta
interlaced by the channels of the two rivers and by irrigation
canals. Intermittent lakes, fed by the rivers in flood, also
characterize southeastern Iraq. A fairly large area (15,000
square kilometers) just above the confluence of the two rivers at
Al Qurnah and extending east of the Tigris beyond the Iranian
border is marshland, known as Hawr al Hammar, the result of
centuries of flooding and inadequate drainage. Much of it is
permanent marsh, but some parts dry out in early winter, and
other parts become marshland only in years of great flood.
Because the waters of the Tigris and Euphrates above their
confluence are heavily silt laden, irrigation and fairly frequent
flooding deposit large quantities of silty loam in much of the
delta area. Windborne silt contributes to the total deposit of
sediments. It has been estimated that the delta plains are built
up at the rate of nearly twenty centimeters in a century. In some
areas, major floods lead to the deposit in temporary lakes of as
much as thirty centimeters of mud.
The Tigris and Euphrates also carry large quantities of
salts. These, too, are spread on the land by sometimes excessive
irrigation and flooding. A high water table and poor surface and
subsurface drainage tend to concentrate the salts near the
surface of the soil. In general, the salinity of the soil
increases from Baghdad south to the Persian Gulf and severely
limits productivity in the region south of Al Amarah. The
salinity is reflected in the large lake in central Iraq,
southwest of Baghdad, known as Bahr al Milh (Sea of Salt). There
are two other major lakes in the country to the north of Bahr al
Milh: Buhayrat ath Tharthar and Buhayrat al Habbaniyah.
The Euphrates originates in Turkey, is augmented by the Nahr
(river) al Khabur 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 sixteen kilometers in width, until it flows out on the
plain at Ar Ramadi. Beyond there the Euphrates continues to the
Hindiyah 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, the Great Zab, the Little Zab, and the Uzaym, all
of which join the Tigris above Baghdad, and the 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 Gharraf,
which was once the main channel of the Tigris. Water from the
Tigris thus enters the Euphrates through the Shatt al Gharraf
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 had been superseded by a
greater obstacle to river traffic, however, namely the presence
of several sunken hulks that had been rusting in the Shatt al
Arab since early in the war.
The waters of the Tigris and Euphrates are essential to the
life of the country, but they may also 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 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.
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.
Data as of May 1988
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