Aswan Dam

The Nile is subject to an annual summer flood as waters from Ethiopia flow down the river. The banks of the river have been used in agriculture since antiquity and rely on the flood to provide and maintain fertility. 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 post-revolution, and at first the US was to help finance contruction with a loan of $270 million, the aid offer was withdraw in mid-1956. The Egyptian government intended to continue the project alone and use the revenues of the Suez Canal to help pay for construction. But in the Cold War struggle for influence in Africa the Soviet Union stepped in in 1958 and possibly a third the cost of the dam was paid for as a gift, they also provided technicians and heavy machinery. The enormous rock and clay dam was designed by the Russian Zuk Hydroproject Institute.

Construction began in 1960. The High Dam, El Saad al Aali, was completed in 1970 with the first stage finished in 1964. The reservoir began filling in 1964 and was first filled to capacity by 1976. The reservoir raised concerns from archaeologists and a rescue operation was began in 1960 under UNESCO. Sites were surveyed, excavated and 24 major monuments were moved.

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 a 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. The reservoir is named Lake Nassar, it is 480 km long and 16 km at its widest with a surface area of 6,000 km², 150 to 165 thousand million cubic meters, 137 million acre-feet of water. It flooded much of lower Nubia and over 90,000 people were displaced. The hydroelectric output is 2.1 gigawatts, the dam holds twelve generators each rated at 175 megawatts. Power generation began in 1967 and when the dam first reached peak output it produced around half of Egypt's entire electricity production (about 15% by 1998).

As well as benefits damming the Nile caused a number of environmental problems. The silt which made the Nile region fertile is instead held at the dam, leading to (expected) silting of the reservoir, some erosion of farmland down-river and the need to use artificial fertilizers, indifferent irrigation control has also caused some farmland to be damaged by waterlogging and increased salinity, a problem complicated by the reduced flow of the river allowing salt water further into the delta. Fish stocks are impacted by the dam, Mediterranean catches have decreased by almost half but a new fishing industry has been created around Lake Nasser. The dam has been implicated in a rise in cases of schistosomiasis (bilharzia).