Saturday, July 26, 2008
Aswan High Dam , Egypt
The Aswan High Dam, replacing earlier dams, contains the River Nile nearly 600 miles (1,000 kilometers) upstream from Cairo by a massive embankment 375 feet (114 meters) high and 3,280 feet (1,003 meters) long, built of earth and rock fill with a clay and concrete core. It impounds Lake Nasser, one of the largest reservoirs in the world, covering an area more than 300 miles (480 kilometers) long and 10 miles (16 kilometers) wide, that holds enough water to irrigate over 7 million acres (2.8 million hectares) of farmland for many years. Its economic and social impact on the lower reaches of the Nile (that is, in the north of Egypt) makes it an engineering feat of some importance, although not necessarily always beneficial.
The annual flooding of the Nile has been the historical life source of Egypt, in what is almost a rainless region. Almost all the population lives within 12 miles (20 kilometers) of the river. The flooding—13 billion to 169 billion cubic yards (12 billion to 155 billion cubic meters)—is caused by late-summer rains on Ethiopia’s plateaus that find their way into the Nile’s tributaries. Late in the nineteenth century, regional population growth was outstripping agricultural production, and the river had to be controlled to recover stability. The first Aswan Dam was built from 1899 to 1902 and raised in 1907–1912 and again in 1929–1934. When its potential to generate the power needed in industrializing economies was realized, hydroelectric installations were added in 1960. But its inadequate storage capacity meant that in years of extreme flooding, sluices would have to be opened to protect the structure, thereby, ironically, inundating the very areas the dam was meant to protect. Designs for the High Dam, 4 miles (6.4 kilometers) south of the existing structure, were put in hand in 1952. Egypt and Sudan signed the Nile Water Agreement in November 1959.
President Gamal Abel el Nasser initiated the Aswan High Dam project. Because of his connections with the Communist bloc, the United States and Britain refused to secure loans, so the Soviet Union provided civil engineers to design the earthen dam and supplied the equipment and 400 technicians and electrical engineers to build the hydroelectric power station. Moreover, almost a third of the estimated U.S.$1 billion cost was met by the Soviet Union, and the remainder was funded by Egypt’s controversial nationalization of the Suez Canal. Construction, commenced in 1960, was complete by mid-1968. The last of the twelve turbines was installed in 1970, and President Anwar Sadat officially inaugurated the High Dam.
Despite causing some ecological problems, the dam brought good outcomes for the people of the Nile valley. For example, with a regulated agricultural system in place, through multiple cropping the nation’s agricultural income has increased by 200 percent. For all that, the poor drainage of the newly irrigated lands has led to increased salinity, and more than half of Egypt’s arable soils are now medium to poor in quality. Village communities were provided with water and electricity. A fishing industry was established, with an annual production target of 112,000 tons (101,600 tonnes) by the year 2000. The hydroelectric scheme generates 2,100 megawatts, about half of Egypt’s annual needs at the time of construction; demand has since increased, and the Aswan High Dam now provides a little over 20 percent. Egypt was untouched by the drought over much of Africa in the late 1980s, and during the following decade the land was saved from several unusually high floods. In 1996 Lake Nasser rose above the spill level for the first time, and plans are in hand to open up more irrigated farmland, even recovering parts of the Sahara Desert.
Nevertheless, the construction of the Aswan High Dam has caused some problems, mostly as cumulative effects of impeding the flow of the river. Farmers have had to turn to artificial fertilizers to replace the nutrients that no longer reach the floodplain. Before the High Dam was built, half the water flowing in the Nile reached the Mediterranean; the millions of tons of silt it once carried to the sea are now mostly trapped behind the dam; consequently the ocean is eroding the coastline. The now-stagnant waters in the Delta destroyed long-standing ecological systems, and the loss of nutrients from the river has drastically damaged the sardine industry in the Mediterranean: 20,000 tons (18,288 tonnes) were caught in 1962; that figure was reduced to only 670 tons (609 tonnes) in 1969. Other branches of the Mediterranean fishing industry were similarly affected. Thankfully, for whatever reasons, there has since been a complete recovery.
The Aswan High Dam also had social and cultural implications. Not least traumatic of these was the displacement of population. More than 90,000 Nubians had to be relocated; those living in Egypt were moved about 28 miles (45 kilometers), but Sudanese Nubians had to move to new homes 370 miles (600 kilometers) away. Much of Lower Nubia was submerged under Lake Nasser, including archeological sites between the First and Third Cataracts of the Nile. At the urging of UNESCO, a rescue program named the Nubia Salvage Project was started in 1960 by the Oriental Institute, University of Chicago. As a result, twenty monuments from the Egyptian part of Nubia (including the front of the rock-hewn tomb at Abu Simbel) and four others from the Sudan were dismantled, relocated, and reerected. Others were documented before their inundation, but some were lost forever without being recorded.