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WEEKLY NEWSLETTER
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Sudan
Index
Except for a small area in northeastern Sudan where wadis
discharge the sporadic runoff into the Red Sea or rivers from
Ethiopia flow into shallow, evaporating ponds west of the Red Sea
Hills, the entire country is drained by the Nile and its two main
tributaries, the Blue Nile (Al Bahr al Azraq) and the White Nile
(Al Bahr al Abyad). The longest river in the world, the Nile
flows for 6,737 kilometers from its farthest headwaters in
central Africa to the Mediterranean. The importance of the Nile
has been recognized since biblical times; for centuries the river
has been a lifeline for Sudan.
The Blue Nile flows out of the Ethiopian highlands to meet
the White Nile at Khartoum. The Blue Nile is the smaller of the
two; its flow usually accounts for only one-sixth of the total.
In August, however, the rains in the Ethiopian highlands swell
the Blue Nile until it accounts for 90 percent of the Nile's
total flow. Several dams have been constructed to regulate the
river's flow--the Roseires Dam (Ar Rusayris), about 100
kilometers from the Ethiopian border; the Meina al Mak Dam at
Sinjah; and the largest, the forty-meter-high Sennar Dam
constructed in 1925 at Sannar. The Blue Nile's two main
tributaries, the Dindar and the Rahad, have headwaters in the
Ethiopian highlands and discharge water into the Blue Nile only
during the summer high-water season. For the remainder of the
year, their flow is reduced to pools in their sandy riverbeds.
The White Nile flows north from central Africa, draining Lake
Victoria and the highland regions of Uganda, Rwanda, and Burundi.
At Bor, the great swamp of the Nile, As Sudd begins. The river
has no well-defined channel here; the water flows slowly through
a labyrinth of small spillways and lakes choked with papyrus and
reeds. Much water is lost to evaporation. To provide for water
transportation through this region and to speed the river's flow
so that less water evaporates, Sudan, with French help, began
building the Jonglei Canal (also seen as Junqali Canal) from Bor
to a point just upstream from Malakal. However, construction was
suspended in 1984 because of security problems caused by the
civil war in the south.
South of Khartoum, the British built the Jabal al Auliya Dam
in 1937 to store the water of the White Nile and then release it
in the fall when the flow from the Blue Nile slackens. Much water
from the reservoir has been diverted for irrigation projects in
central Sudan, however, or it merely evaporates, so the overall
flow released downstream is not great.
The White Nile has several substantial tributaries that drain
southern Sudan. In the southwest, the Bahr al Ghazal drains a
basin larger in area than France. Although the drainage area is
extensive, evaporation takes most of the water from the slowmoving streams in this region, and the discharge of the Bahr al
Ghazal into the White Nile is minimal. In southeast Sudan, the
Sobat River drains an area of western Ethiopia and the hills near
the Sudan-Uganda border. The Sobat's discharge is considerable;
at its confluence with the White Nile just south of Malakal, the
Sobat accounts for half the White Nile's water.
Above Khartoum, the Nile flows through desert in a large Sshaped pattern to empty into Lake Nasser behind the Aswan High
Dam in Egypt. The river flows slowly above Khartoum, dropping
little in elevation although five cataracts hinder river
transport at times of low water. The Atbarah River, flowing out
of Ethiopia, is the only tributary north of Khartoum, and its
waters reach the Nile for only the six months between July and
December. During the rest of the year, the Atbarah's bed is dry,
except for a few pools and ponds.
Data as of June 1991
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