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Iraq
30 Years of Progress
Iraq
Land and People
The
Physical Elements
Three primary
factors must be known about Iraq before any physical,
human or economic elements can be sorted and evaluated.
Information about where Iraq is, how large it is, and
what shape it has is essential at the beginning of such
geographic study. Each plays a significant role in the
geography of the country and the region as a whole.
A.
Location
Iraq, in terms of
latitude and longitude, lies between 29°15’N, and
38°15’N, 38°45 and 48°45 E. That means it is located
entirely within the north temperate zone where it enjoys
stimulus seasonality of climate.
The country is
bounded by several Arab and non-Arab States: Turkey on
the north, Iran on the east, Syria and Jordan on the west
and Saudi Arabia, Kuwait and the Arab Gulf on the south.
Throughout history, Iraq’s inhabitants have entered
into peaceful relations with their neighbours, and their
civilization originally based on agriculture should
gradually have given way to one in which trade had a
major part. This is more true at the present time. With
an immense agricultural and mineral wealth, there is no
necessity or inducement not to assert the same historical
relations. There is no need to speak about the brotherly
ties that bind Iraq with the surrounding Arab states and
its sincere efforts for Arab aspirations to become true.
At the regional and
global levels, Iraq has had extraordinary importance
since its early days. Its location is at the meeting
place of Asia, Africa and Europe, and along the shortest
land span between the Indian Ocean and the Mediterranean
making Iraq on of the pivot area in the world.
The Euphrates and
the Tigris not only supplied water for irrigation and man’s
more immediate personal needs, but were also used for
movement, which is always along the lines of least
resistance. It was comparatively easy to pass from
Mediterranean shores across the Euphrates.
With the advance of
civilization and as the conditions of living improved,
the location of Iraq has become an increasingly important.
Modern land roads are crowded with vehicles carrying
goods from far away places to various destinations. Clear
blue skies are crossing-points for international air
routes.
B. Area
Iraq has a total
area of 438,317 square km. The extent of its national
territory, compared with that of European countries,
exceeds all but the former Soviet Union, France and Spain.
Gifted with a
variety of natural resources, it can support a large
population and enables the country to attain its maximum
strength. The land is able to produce its
fruits on greater scale than in the past, and Iraq will
be as prosperous as ever.
C.
Shape
The shape of the
area is an advantage to Iraq. It has almost an ideal
circular plan, and Baghdad, the capital city is located
at the centre. Such a compact shape is an asset from the
point of view of economic, cultural and national unity.
This has helped to minimize the difficulties of travel,
to decrease diversity of physical environment and the
length of the boundary to be guarged. It is unusually
easy to travel in Iraq. No more than a few hours are
needed to travel by car from Baghdad to any place in the
country.
D. Climate
Lying in land,
continental extremes are climatic characteristic in Iraq.
Dry and hot summers and cooler wet winters are the main
features. For the most time of the year, Iraq is under
the influence of high pressure, with northerly dry and
warm winds. In summer, this steady air movement from the
north and northwest, forms a hot, dry wind which often
blows.
In winter, this
inflow is frequently interrupted by cyclonic activities,
a part of the irregular westerly circulation of middle
latitude which dips southward with the oscillation of the
subtropical high pressure belt in the direction. The
yearly average number of these east moving cyclones
amounts to 120. Most precipitation is associated with
these weak cyclones.
Occasionally, a well
-developed cyclone may remain stagnant over the country
for several days. This draws in large amount of maritime
air associated with considerable amount of rain lowlands,
and heavy snowfalls in the mountains. In general, there
is gradual rain increases in a north east direction, from
50mm in the south-western corner to a 1000mm in the high
mountainous area of the northeast. In the latter areas,
precipitation is influenced by a combination of cyclonic
activity and orographic barrier. The 200 mm line is an
important line. This isohyet, in general, indicates the
southern limit of the rain-fed agricultural zone. But the
annual variation of the rainfall is very high, and the
southern limit of the rain-fed agricultural zone dose not
have a fix position. Some winters are dry, while others
are much wetter. Accordingly, isohyets shift to the north
east in dry years, and to the south-west in the wet ones.
Time and geographic
variation of rainfall are important factors for dry
farming. Some additional rain in spring can favourably
influence the yield of wheat and barely. There are also
differences in the monthly rainfall data. The number of
rain days in Basra, Rutba, Baghdad and Mosul are 51,55,48
and 59 respectively.
Temperature
A large daily and
annual temperature range is a pronounced continental
climatic characteristic. The annual average temperature
in Baghdad is 22.5° C while the mean daily minimum
temperature in January is 4° C the mean maximum of
temperature in August is 43.2° C.
The air humidity is
rather low. In Baghdad, the relative humidity in August
ranges from 44 percent at the highest to 21 percent at
the lowest. With clear days ranging from 198 in Mosul to
207 in Baghdad, Iraq is an area of high thermal energy,
and an intense solar energy becomes a renewable national
resource. A long growing season (frost-free period)
enables the country, with available water resources, to
grow almost anything that can be grown in middle and
lower latitudes.
Climatic Types
The climate of Iraq,
in terms of temperature and rainfalls, may be classified
into three main types.
- Mediterranean
Climate
This type is characterised by cool,
wet winters, and hot, dry summers. It is more
restricted to the mountainous areas. Therefore
snowfall is not uncommon, and the amount of
rainfall varies from 400mm at the lower area to
1000mm on highest ones. The average summer
temperature doses not exceed 35° C on the lower
slope s, but it is much less on the higher slopes.
- Steppes
Climate
This type is transitional one between
the Mediterranean type in the north and the
desert in the south. High temperature and small
amount of rain are the main limiting factors.
Rainfall range between 200mm to 400mm. It comes
during the cool season of the year where the
evaporation rate is the lowest. This is a natural
pasture area for a large number of sheep flocks.
- Hot Desert
Climate
Lowlands in Iraq are
a hot desert. This is an area of a high thermal energy.
With clear air in summer, solar isolation becomes
intense, and air temperature rises to a maximum of 45-50°
C. the daily range of temperature is very large. Nights
are rather cool, and the people find it very refreshing
to sleep in the open air. In winter times, warm and sunny
weather prevails, and the temperature rarely drops under
freezing point.
E.
Physiography
Mountains, plateaus,
hills and valleys, planes and inland water-covered areas
are the major geomorphic forms, which, in varying
combinations, make the topography of Iraq. These
geomorphic forms exert a strong influence upon the
cultural and economic patterns of the country and,
together with the climate, provide a permanent back-drop
against which the history of Iraq is enacted. It is very
interesting to find in a limited area, like that oIraq,
good example of land forms of the earth's surface.
Iraq, together with
the Arab Gulf, is a down-dropped block, like that of the
Red Sea, trending also in the same direction. The country
was lying, millions of years ago, in a shallow sea.
Marine sediments, mainly limestones, were deposited, and
streams from the surrounding land surface brought
alluvium deposits into it. Thus, the sea area became
gradually restricted.
A mountain movement
starte50 to 30 million years ago, and a series of
sedimentary beds, lying at the bottom of the shallow sea,
has been regularly bent into arches and troughs, that is,
into anticlines and synclines. The arches formed the
mountains, and troughs formed the valleys. The mountain
building movement is still going on, but a very slow rate.
During the three
main pluvial periods in Iraq, associated with glacial
ages in Europe, climate was more humid than at present
and a considerable period of river erosion modified the
land surface. The mountains were cut down and the valleys
as well as the southern part of the extensive geocycline
were filled up with pebbles, gravel, sand, silt and clay.
Inter-pluvial phases, with a climate similar to that of
the present time, interrupted the erosional process, and
river terraces have been formed along the rivers and
their tributaries in central and northern Iraq. Three
broad erosional river terraces, for example, can be seen
in Tikrit along the eastern banks of the Tigris.
Four broad
topographic regions, in terms of area altitude, can be
distinguished in Iraq. They are:
- Mountain
Region
Bold,
majestic mountain scenery covers an area of
92,000Km or about 21 percent of the total area.
It extends mainly in the northern and north-eastern
parts of the country. The mountains consist
mainly of parallel anticlinal ridges separated by
elongated synclinal valleys. But they are united
by narrow gorges, the outlets of the drainage of
the interior basins. The mountains for the
greater part are eroded, and the detrital
material has been deposited in the valleys and in
the area in front of the mountains. The mountains
consist of various folded limestone layers
varying from simple foldings in the south to
complicated foldings in the north. Sindy, Zab and
Rawandooz geosycline separates
them. The average elevation of the former area
ranges from 5,000 to 6,000 feet, while it reaches
an elevation of 7,000 to 10,000 feet in the
complicated folded one. Faults, metaphoric rocks
and glacial landforms are not uncommon in this
area. The highest mountain peak in the country is
Hassarrost, it stands 3,607 meters above sea
level.
Water-falls,
casades, rapids and deep gorgeo are common
geomerphic phenomena in the area. Plains of a
considerable size, such as Rania and Shahrazoor,
separate two mountain areas. The former, is a
kidney-shaped plain, in the Lesser Zab area, with
an elevation ranging from 1,600 to 2,000 feet. It
extends for 30 Km and its width varies from 20 to
30 Km. A basin-like Shahrazoor plain varies in
elevation from 1,500 to 2,000 feet above sea
level. From east to west, Shahrazoor extends for
45 km, but it narrows down to 50 Km in the north-south
direction.
Natural
vegetation in these mountainous areas reflects in
a very clear way local climatic conditions. The
lower treeeline has thermal and rainfall
limitation. It is found in areas about 1,000
meters high and with an amount of annual rainfall
not less than 500. Juniper trees draw at the
upper parts of the forest belt, while maple,
walnut, ilmond and ash trees are widely grown at
the middle altitudes. The pistachio and olive
trees thrive in dryer places. The inner treeline
is more restricted to areas of 1,500 meters above
sea level, and the annual amount of rainfall is
not less than 500 mm. Alpine graces grow at
higher elevations. These are natural grazing
areas for large herds of
sheep
and goats. In summer times, shepherds, following
the slow melting snow, may drive their herds as
high as 9,000 feet. This can be seen on the slops
of Hassarrost mountain north-east of Rawandooz.
In the fall, the process of migration is reversed.
Agriculture
of extensive type is dominant in the lowlands.
Arable lands in Rania and Shahrazoor plains are
mainly fields of wheat and barley in winter.
While mixed intensive farming is the major
practice during the rest of the year, vegetables,
fruits, sugar beet and diary products are
becoming the main cash crops in the area.
Cool climate.
Snow-clad peaks, deep river valleys, forested
slops and water falls provide a very good bases
for thriving resorts. Long and hot summer months
encourage a large number of people from the
cenrte and southern parts of the country to
travel northward. Here they may enjoy a
refreshing cool weather and relax beside a
charming mountain scenery. Some of these places
have their charm even in winter times, such as
Haj Umran (Arbil Province) a resort located on
the side of Hassarrost mountain at about 1,780
meters above sea level. The temperatures in
winter may drop sharply as low as 15 degrees
centigrade below zero. Nearby smooth and gentle
slopes, covered with powdery snow make them ideal
for skiing and other winter sports.
- Undulating
Lands
A
fairly hilly landscape located south and west of the
mountain region. It covers an area of about 42,000Km, or
nearly 9.6% of Iraq's total area. Although there are some
similarities with the former region, general landscape
differences stand sharp. The area is somewhat folded in
the later phase of folding. It consists of low parallel
hill ridges, wide shallow valleys and extensive plains,
in which various streams have cut their valleys. In
general, average altitude varies from 200 to 1,000 metres.
Local relief is more than 500 feet per square kilometer,
but less than 2,500 feet. Beds of gravel, conglomerate
and sandstone make up the area. It can be divided, in
terms of geomorphic landforms structure, surface rocks
and degree of erosional process, into a number of plains,
plateaus, mountains and hill ridges. A briefly discussed
example of each may summarize the whole picture of the region.
The mountains are
relatively low. Sinjar, is an anticlinal range, extending
in a north-easterly direction. Its elevation varies from
4,800 to 2,800 feet. The southern
edge of the mountain range is a highly dissected part.
Strike valleys and minor scraps are common.
Plateaus are small
in number, and the best known are those of Mosul and
Kirkuk. The surface of Mosul plateau is dissected by
shallow valleys with hills rise to 1,000 feet above the
surrounding valley bottoms.
Plains are found
within the area such as the plain of Sinjar and Arbil.
The latter is a synclinal triangle basin filled with
alluvium deposits. Its elevation varies from about 1,800
feet at the eastern edge to 1,000 at the western parts.
Fertile soils together with an adequate amount of winter
rain provide a good basis for agricultural land use.
Wheat and barely are the main crops in winter, while
underground water resources supply enough irrigation
water for many agricultural products during the other
seasons.
The economic
importance of this region may be summarized as follows:
- Mineral wealth,
mainly oil and sulphur: large oil fields are
found in Kirkuk are and Ain Zalah, while sulphur
deposits are mined in two major areas namely, Al-mishraq
and Fatha.
- Agricultural
products, such as wheat, barely, sugar beet,
cotton, vegetables, fruits and dairy products,
from the basis of a solid agricultural economy.
- During the
winter a significant growth of annual grasses and
legumes, depending on rainfall, provides good
natural pasture lands. Sheep and cattle raising
industry is widely-spread throughout the area.
Agricultural
industries (sugar, cotton and woolen textiles, diary
products, cigarettes, etc.) enjoying special government
attention are found in different localities throughout
the region.
3. The
Depositional Plain
It is the plain of
the twin rivers, the Tigris and the Euphrates, referred
to in ancient as Shinar and later on was called Asswwad,
because of its high agricultural productivity. The plain
is located in central and southern Iraq with a numbeof
distinct landscapes. The undulating lands are to the
north, the western plateau to the west, Zagros mountain
to the east and the Arab Gulf to the south. The plains (including
marshland and lakes) cover an area of 132,500 Km or 30.2
of the total national area. It has a northwest-southeast
orientation, trending in the same direction of the
Tigris, Euphrates and Shatt al-Arab.
Geologically, the
plain occupies the southern part of an extensive
geosycline. It was filled up by sedithe rivers brought in
during the quarternary and recent geological periods.
Besides the fluviatile sediments which are carried by the
twin rivers, some material of aeolian origion, blown out
of the desert, is accumulated and mixed with fluviatal
deposits. As a result of flood and irrigation, rather
thick layers of mud have been deposited on top of the
original soils. Nearly the whole plain is now covered by
this silty material.
The elevation of the
region increases gradually from south to north. From mud
at sea level along the Arab Gulf coast, to more than 32
metre around Baghdad, a distance about 654 Km away. But
the increase is rather sharp in a west-east direction.
The elevation increase from 5 metres above sea level, at
the basin-like area north of Basra, to 100 metres in both
directions within a much shorter distance.
Along the eastern
borders, rivers tumbling down from the eastern mountains
helped to form a number of alluvial fans. A series of
adjacent fans coalesced to form an extensive piedmont
alluvial plain. The material comprising these fans varies
in texture, from coarse boulders and pebbles at its head
to find material down its slope. On such alluvial fans
Mendile and Badra are located. Here is a good example of
a successful agricultural land use. Gentle slopes,
fertile loamy soils, good air drainage in winter and flow
irrigation were utilized in an excellent way to grow date
palms and citrus fruits.
Most of the plain
appears to be dead flat. In areas away from rivers or
cultivated land, one may look to the full circle of the
horizon without seeing any perceptible slope. But natural
levees, irrigation canals, low lying hills may break the
monotony of the land.
Rivers flow with a
gentle gradient and are unable to carry all their load of
sediment. For this reason, natural levees capped with
dikes border the Tigris and Euphrates. Flow irrigation
canals can be easily led away from the rivers. Many parts
of the plain have poor drainage, especially in the basin-like
area in its southern part north of Basra.
Marshlands occupy an
area of more than 35,000 square Km. Their geographic
distribution may be seen in three distinct bells. One
east and west of the Tigris, the other
is Al-Hammar lake and the third between the Hilla canal
and the Euphrates.
Reeds and bushes
thickly cover the banks and shallow portions of the
marshes. These provide an excellent nestling grounds for
migrating birds in winter. The main crops grown on the
marsh borders are rice, millet and, in winter tomatoes,
while animal husbandry is restricted to raising buffaloes.
This region has a
very important economic role. It provides the country
with large agricultural areas and with sites for its
large cities like Baghdad, Basra and many others. The
level land is easily titled and it yields abundant crops.
It may be that agriculture has been carried on here
longer than any where else on earth . in addition to the
above mentioned crops, wheat , barley, cotton, corn,
sugar cane, fruit and vegetables are produced in large
quantities. The Shatt-al-Arab is the largest date-palm
area in the world. Dairying and poultry farms are widely
spread.
Minerals are also
found. Oil fields in Basra and Misan are among the major
oil fields in the world. Oil, natural gas, salt,
limestones, sand and clay are row materials for many
flourishing industries in the region.
Inland lakes, such
as Al-Habbaniya on the Euphrates constitute a fine
holiday resort ideal for swimming, fishing, boat-racing
and sunbathing. Marshlands such as Al-Hammar, Huwaiza and
Sanaya attract many tourists.
Environmental pecularities as well as sunny and warm
weather in winter encourage large numbers of people to go
boating, fishing and duc hunting. It was on the marigins
of these marsh lands that human history began.
Everywhere you go in
this region there are traces of achievement of ancient
civilizations. Every historical period has its own
characteristics and its own geographical distribution. It
is a cultural mosaic nicely arranged from the southern
part of the plain, where Sumerian civilization
flourished, to the Babylonian civilization in centre and
a widely Arab-Islamic heritage spread in between.
These have become
cultural centres visited all the years round.
The Western
Plateau (Deserts)
This is the largest
physiographic region in the country. It occupies and area
of 171,817 square Km, or about 39.2% of Iraq total area.
The surface rises gradually from 400 feet in the east to
2,000 feet in the west. While rock formations change to
be of a younger geological period as one goes from west
to east. Surface drainage takes a west-east direction in
general, but manty streams bring large amounts of water
from Sinjar mountain to be drained southward to the Wadi
Tharthar, the largets depression in Iraq. since 1956, it
has been used to store excess Tigris water diverted near
the Samarra Barrage. It was lately connected with the
Euphrates and the Tigris by two feeding canals to divert
enough irrigation water back to the rivers.
Within this very
extensive region, there is a number of different plains;
al-Widian (valleys), Jezira (island), al-Hijara (rock),
al-Hamad and Dibdibba. The differences are based on
physical factors such as relief and rock formations. A
brief informative discussion of each may be useful to
comprehend the whole picture.
The Widian Plain,
developed in an area of limestone and gypsum rock level
to undulating with shallow to rather deep valleys which
have a dendirtic pattern. In the northern Widian area is
the large Ga'ara depression north of Rutba.
The Jezira is what
has remained of an old inlandsea. It a dissected up land
area across which the rivers flowing in a well-developed
valley. At present it is a large desert and steppe area.
In winter and spring, especially after a good rainy
season, the northern portion is covered by desert grasses
which provide grazing land for camel sand sheep. There
are many saline lakes, marshes and depressions. Wadi
Tharthar is the largest one.
Al-Hijara is a flat,
stony plain with some shallow valleys.
Al-Hamad plain is at
the extreme western corner of the country.
It developed on limestone rock formations. The plain is
nearly level and featureless.
Dibdibba plain
occupies the southern portion of this region west of
Basra. It developed on sand and gravel and the surface
varies from level to slightly rolling land. amid such a
flat plain Sanam mountain rises to 300 feet. It is some
sort of a lacolithis dome with a limited area. Tamarask
bushes are planted for different purposes.
Landforms of
wrappings, foldings and faults are found throughout the
region. Al-Ga'ara and Assalman basins occupy eroded
domes, while geomorphic arid landforms are found in many
localities. Buttes and mesas are characteristics of
isolated remnants of hard resistant limestone. Sand dunes
30 metres high m, as well as low Burkhan ones, are
typical desert features. Caves, dry underground channels
and springs are hard topographis phenomena associated
with limestone area, Water-springs in Ain al-Tamur and
bituman and sulphorated briane springs near Hit.
At present the
region has seen considerable changes. Since the 17-30
1986 Revolution a crash development programme has been
put to work. Speedy high ways and new rail way line cris-cross
the region. Dams have been build across a number of
valleys such ah Houran, to store large quantitities of
water flowing after heavy torential rains.
Phosphate deposits
are commercially mined and exported. Sands are used in
the glass industry. Many edxperimental farms and new
settelemnet have been build. Water covered areas the
region, like al-Habbaniya and Tharthar, are surrounded by
well developed recreations centres. All in all, the
region has become an active national area.
Rivers and
Lakes
Water resources in
Iraq are controlled by the twin rivers, the Tigris and
the Euphrates. Both rivers have their headwaters in the
humid mountains of Turkey where much of the precipitation
falls as snow, and both are subject to wide seasonal
fluctuation.
In the rolling
areas, the rivers flow in well-defined valleys so that
irrigation is normally limitto their flood plains. As
soon as they enter the depositional plain they become
meandering rivers. The Euphrates enters the plain near
Hit and becomes irregular south of Hindiya, while the
Tigris' entrance is at Balad and becomes irregular south
of Kut.
South of these
entrance points the rivers flow with a gentle gradient
and their currents are unable to move the sediment
brought down from the hills, deposition follows, and
natural levers are developed. Here the Tigris and
Euphrates flow on lever ridges above the level of their
extensive floods plains, thus making possible the
extensive network of canals which in ancient times
converted into the Garden of Eden, and which
in modern times have made this the greatest date-producing
region in the world.
Rivers in arid
regional lose water by seepage, evaporation and diversion
for irrigation. This is notably true with Tigris and
Euphrates, the law-water discharge of the Tigris past
Baghdad amount to 158 cubic metres per second. The mean
flow is 1236, and in flood it rises to 13,000. So much
water is lost down-river that near the junction with the
Euphrates the corresponding figures are 11,78 and 179
cubic metres. These figures may have changed due to many
river controlling and irrigation schemes, which have been
done lately, but the discharge pattern still holds true.
At their southern ends both rivers enter vast marshlands
areas. To have a more comprehensive picture of each river
some details are required.
The Euphrates
The Euphrates has an
over-all length of 2,900 kilometres, and a drainage basin
of 289,300 square kilometres. It rises in the rugged high
humid mountains of eastern Turkey. Before it enters the
Arab land in Syria near Tarabulus, the river already has
flown for 440 kilometres through Turkey. In Syria the
river flows 675 kilometres in a level and arid land,
where it meets its main tributaries, the Blaikh and
Khabour.
The Euphrates enters
Iraqi territories at Husaiba village to start a long 1015
kilometres journey in a south-east direction. Cutting its
way through the western plateau, the river flows in a
broad, shallow and well-defined valley passing rapids and
cataracts in many places. Islands amid its channel are
not uncommon. Passing Hit the river starts to flow
through its gradational plain. To the south-west of
Ramadi, 36 kilometres south of Hit, is Habbaniya lake. It
is a natural retention basin with a good storage capacity.
Engineering works, now diverts surplus flow into this
reservoir and reduce the likelihood of serious flood. It
has a maximum surface area of 426 square kilometres and a
storage capacity of 3.4 billion cubic metres. Any extra
amount could be discharged to Abu Dibis depression south
of it.
In the northern part
of the depositional plain the topographical position of
the Euphrates is somewhat higher than of the Tigris. Due
to this fact the land northwest and southwest of Baghdad,
that is north of Falluja and Hindiya, is irrigated by the
Euphrates water. Near Faluja the river becomes 40
kilometers away from the Tigris. At Hindiya the Euphrates
branches off into two rivers, Hilla and Hindiya. After a
short distance they meet again to form a single channel
north of Samawa. Still flowing in a southeast direction,
the Euphrates passes through Nassiriya and Suq-ash-shuyukh
before it enters Hammar Lake. There it flows in undefined
channel til it joins the Tigris at Garmat Ali north of
Basra.
Recent engineering
work has given the river a new appearance and a different
flow region. Seven kilometres north of Haditha, ''Al-Qadissiya
Dam'', 8150 meters long and 54 meters high, has been
recently completed across the river. A long lake will
extend in front, and the variable discharge region of the
river will be well under control.
The Tigris
The Tigris measures
1970 kilometers and has a drainage basin 19,000 square
kilometers. It rises at the humid mountains of southeast
turkey. The river at the upper course has a number of
small creeks. A single channel formed after an eastern
tributary, the Tigris, and western one, Botan Sou, meet
together. Flowing in a south-eastern direction, the river
passes through rugged Turkish areas for 300 kilometers.
Within Iraqi national territory, the Tigris (measured at
1,290 kilometers) first passes through the border village
Fiesh Khabour. Then it passes through Fatha which
separates Hamrin and Makhool uplands. Within this area
the Tigris flows in a well-defined stony banks and a
narrow flood plain. This picture can be seen north of
Samarra. Starting from Balad the river flows in a
featureless depositional plain. Associated with a gentle
gradient, meandres are numerous notably in the area
between Baghdad and Kut.
Above Kut barrage
the Tigris branches off to Garraf and Dujailah canals.
Form both sides, five more canals branch off at Amara
namely, Misharah and Kahlaaon the left and Bitairah,
Mijar Al-Kabir and Mijar Al-Saghir on the right. Due to
this fact, the Tigris channel becomes very narrow and the
volume of its water is very limited. South of Uzair, with
increasing amount of water running back to the river from
the surrounding marshlands, the channels widens again
till it joins the Euphrates at Garmat Ali.
The Tigris level is
usually high in April and May and law in September and
October. This shows a little difference from that of the
Euphrates where the level is high in April and has its
maximum in May. The minimum is usually in September and
October. Another significant difference is that the
Tigris receives an additional amount of water from a
number of tributaries within Iraqi national territory.
These are:
a) Khabour which
rises in the Turkish highlands and joins the tigris at
Fiesh Khabour.
b) Zab Kabir (Greater
Zab ) rises in the Turkish highlands nad joins the
ancient historical city of Namrood. This is the main
tributary in terms of the volume of water. It has been
estimated that 33 per cent of the water that flows in the
trunk river is brought by Zab Kabir.
c) Zab Zaghir (
Lesser Zab) rises in the eastern highlands outside the
country and joins the Tigris south of Sherqat.
d) Adhaim: the
headwaters are entirely within Iraqi national territory.
It joins the Tigris at Balad. Adhaim is a seasonal river.
Winter rains bring large mountains of water heavily
loaded with sediments, but it is merely a dry channel in
summer.
e) Diyala: the
headwaters are partly within Iraqi eastern highlands, and
it joins the Tigris a short distance should of Baghdad.
Like the Euphrates,
the Tigris has its own flood retention basin with a very
large storage capacity. By way of Samarra barrage the
Tigris floodwater can be diverted to a structural basin,
namelt al-Tharthar. The maximum storage capacity of the
depression is 85 billion cubic meters. It is the largest
man-made reservior in the world next to Nasir Lake in
Egypt. Upstream dams, across the Tigris and the
tributaries, also hold back water for irrigation. The
latest to be erected across the Tigris is a 3,500 meters
long and 126 meters high ‘’ Saddam Dam’’ near
Mosul. Others are Derbandikhan and Hamrin dams on Diyala
and Dokan Dam on the Lesser Zab. More dams are planned
such as Bakhma on the Greater Zab and Adhaim dam. All
will be multiple purpose dams.
To the length of he
twin rivers must be added 190 kilometres for the Shatt-al-Arab
formed by their junction. This is to place the Shatt-al-Arab
system among the 16 longest rivers in the world. Karun,
which flows from the east, is the only tributary. With a
depth of 32 feet, oceanic ships can move upstream to a
distance of 80 kilometres away from its outlet at the
Arab Gulf.
Iraq
is the largest date-producing country in the world.
Eighteen million of its 30 million trees grow along the
Shatt-al-Arab where the tidal rise and fall of the lower
river send surge of fresh water into the canals which
properly irrigate the date groves.
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