Nile water control

Year:1902 & 1970

Duration:4 years & 10 years

Cost:Aswan High Dam: $1.1bn (about £11.5bn today)

Country: Aswan, Egypt

What did this project achieve?

Construct a dam to control flooding, generate hydroelectricity and irrigate farmlands

The Aswan dam – also known as the Aswan high dam – was built across the river Nile in southern Egypt near the city of Aswan.

The dam is 3,830m long and 111m tall. It’s 980m wide at the base, tapering to 40m wide at its crest. The structure contains 43 million m3 of material – mostly rock and clay.

It was designed to control the flooding of the river Nile just like its 1902 predecessor, the Aswan low dam. Egyptians have relied on the annual flood seasons of the river both for drinking water and to irrigate farmlands for thousands of years.

The Aswan high dam created Lake Nasser, a reservoir named after Egyptian president Gamal Nasser. At 550km long and 35km at its widest, the lake has a surface area of 5,250km² and holds 132km³ of water.

The high dam was designed to replace the function of the Aswan low dam further downstream. The lower dam was 1,950m long and stood 22m high. It had a navigation lock on the western bank to let ships through.

At the time it was built the low dam was the largest masonry dam in the world, built from locally-sourced Aswan granite.

Engineers built the 1902 dam with 180 2m wide under-sluices at its base. These channels allowed water and silt to pass through the dam when the Nile flooded. The technique stopped the reservoir from silting up.

The growing Egyptian cotton industry and its need for water saw the Aswan low dam raised twice, between 1910 and 1933. The additions brought it up to a height of 36m, boosting the amount of water it could hold to 58m³.

Egypt’s growing population and the government’s desire to modernise had made the low dam less effective by the 1950s. There were also fears that the low dam’s higher wall could result in the flooding of the ancient Philae temple upstream. Plans were drawn up for a second, higher, dam upstream.

Building the Aswan high dam was needed to control flooding of the Nile more efficiently, provide more water for irrigation and generate more hydroelectricity. All these factors were crucial to the country’s plans for industrialisation.

The high dam scheme was funded by a loan of $1.1bn (about £11.5bn today) from the Soviet Union which was keen to win influence in the region at the time.

Soviet engineers also helped designed the scheme through the Moscow-based Hydroproject Institute.

Difference the dams have made

As Egypt has virtually no rainfall its agriculture industry depends almost entirely on irrigation. The Aswan high dam releases around 46km² of water into irrigation canals every year.

Approximately 33,600km² of the Nile valley and delta benefit from the water the high dam scheme provides.

Both the low and high dams have protected Egypt from floods and droughts as well as boosting electricity production. The high dam has become a tourist attraction that brings revenue to the local economy.

How the work was done

The Aswan high dam was designed as a rock fill dam by engineers at the Moscow-based Hydroproject Institute. The Soviets also provided technicians and heavy machinery for the scheme.

Unlike a masonry dam, a rock fill dam relies on compacted dirt and the friction between small particles of stone and soil for its stability.

Engineers sited the high dam in a bed of rock to provide a solid foundation for the structure which was mostly constructed from stone and clay.

The project team built a series of emergency spillways – overflow channels – around the structure. These aimed to deal with the increased volumes of water that heavy rainfall might bring in the future.

Project workers had to relocate more than 90,000 people from areas the high dam was set to flood. Some were moved as far as 45km away from their original homes.

Around 25,000 Egyptian engineers and other workers played a part in the scheme.

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The eighth wonder of the world

Nikita Khrushchev

Soviet president, at a ceremony to divert the course of the Nile during construction of the Aswan high dam. May 1964.

Fascinating facts

At just over 4,000 miles long, the Nile is the longest river in the world.

22 of Egypt’s ancient monuments and temple complexes were moved to save them being flooded by the rising waters that would be created by the Aswan high dam.

Teams of engineers and archaeologists moved structures including the Abu Simbel temples in the south of the country. The complex included 4 statues of King Rameses 2 - each of them 21m tall.

The Abu Simbel complex was shifted to ground 65m higher and 200m further back from its original location near the banks of the Nile. The project cost $40m (about £300m today).

People who made it happen

  • Client: the Egyptian government
  • Chief engineer: Sir Benjamin Baker, ICE president
  • Contractors: John Aird & Co

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