History
As the population along the river grew there came the need to control the flood waters to protect farmland and cotton fields. The British began construction of the first dam in 1899 and it was completed in 1902. A gravity dam, it was 1,900 m long and 54 m high. The initial design was soon found to be inadequate and the height of the dam was raised in two phases, 1907-1912 and 1929-1933.
When the dam almost overflowed in 1946 it was decided that rather than raise the dam a third time a second dam would be built 6 km up-river. Proper planning began in 1952, just after the Nasser revolution, and at first the US was to help finance contruction with a loan of $270 million. Construction began in 1960. The High Dam, El Saad al Aali, was completed on July 21, 1970 with the first stage finished in 1964.
The Aswan High Dam is 3,600 m long, 980 m wide at the base, 40 m wide at the crest and 111 m tall. It contains 43 million m3 of material. At maximum, 11,000 m3 of water can pass through the dam every second. There are further emergency spillways for an extra 5000 m3 per second and the Toshka canal links the reservoir to the Toshka depression. With hydroelectric output of 2.1 gigawatts, the dam holds twelve generators each rated at 175 megawatts. Power generation began in 1967. When the dam first reached peak output it produced around half of Egypt's entire electricity production (about 15% by 1998). The effects of dangerous floods in 1964 and 1973 and of threatening droughts in 1972-73 and 1983-84 were mitigated.
