Aswan
High Dam
This
huge dam was a vast and
ambitious project. It was built to hold back the waters of the
world’s longest
river, the Nile. The dam has helped to create a steady flow of water
all year
round, and provides electricity for the country's factories and towns.
NILE
FLOODS
Since ancient times, the River
Nile has flooded every year. The floods spread fertile mud over the
land
helping farmers to grow their crops. But often big floods destroyed
homes and
farmland. At other times of the year there was drought.
CONTROLLING
THE
NILE
In 1902 engineers built a dam
just south of Aswan to control the floods. This dam was made higher in
1912 and
again in 1933. But this first Aswan Dam was still not enough to control
the
Nile fully.
Building work started on the
Aswan High Dam in 1960. The dam is made of earth and granite rock-fill,
with a
core of clay and cement. It is over 3.6 kilometers wide, 111 meters
high and 40
meters thick at the too. At its base on the river bed it is a massive
925
meters thick. The dam took ten years to build.
LAKE
NASSER
Aswan High Dam was officially
opened in 1971. During the rainy season, the dam holds back the Nile's
rising
waters. As the waters rose behind the dam, they gradually formed a
reservoir
more than 500 kilometers long. The new reservoir was called Lake Nasser
after
the Egyptian president.
CREATING
THE LAKE
Around 50,000 people had to
leave their homes to make way for the reservoir. They were taken to a
new
farming region 50 kilometers north of Aswan. Several ancient temples
and
islands were flooded, but some were rescued. In a huge-scale operation,
the
temples of Ramses II and Nefertari were cut into 30-tonne blocks and
put
together again, piece by piece on hills overlooking the river. This
difficult
work took four years. Other small temples were also moved from an
island in the
Nile which was to be totally submerged.
BENEFITS
The water stored in Lake Nasser
is used to irrigate farmland during dry periods and throughout the
year. More
crops can now be grown every year, producing more food to feed the
growing
population. As the water pours through the dam, it also drives
turbines, which
generate half of Egypt's electricity.
PROBLEMS
This
human attempt to control nature has brought
many problems as well as benefits. The dam stops fertile mud from
moving
downstream. So that farmers have to use more chemicals to fertilize
their land.
Since the dam was built, there has also been an increase in a disease
carried
by tiny worms in the Nile's water snails. Yearly floods used to keep
the
numbers of snails down. A rise in the water table has also brought
salts to the
surface, which makes the land infertile.