|
Iraq
Major Geographical Features
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 . 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
|
