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Egypt, which has very little rainfall, has always depended for its existence on water brought by the Nile from the distant uplands of Abyssinia and Central Africa. During the summer the flow of the Nile is very low. Therefore it was necessary to build a dam across the Nile. This dam would form a reservoir in which part of the winter waters could be stored and then released to the farmers’ fields during the summer by a system of irrigation canals.
So, between 1899 and 1902, the Egyptians built a dam, which they called “The Aswan Dam”. It was about 917 km south of Cairo. Between 1929 and 1933, the dam was heightened. It was then 34.4 m high and 2.1 km long. As the population grew, the demand for water continued to increase. So, further conservation of the flood waters of the Nile was essential. In 1959, the construction of the “Saad-El-Aali” (High Aswan Dam) was begun and was completed by 1969.
The new dam is sited nearly 6.4 km south of the original Aswan Dam. It is built of sand, clay, and rockfill, and is 111 m high and 3.8 km long. It is one of the largest dams in the world. The reservoir, 500 km long and an average of 8 km wide, is large enough to store a high Nile flood of one year against the possibility of a low flood in the succeeding year.
The High Aswan Dam is a very good example of man's constant efforts to overcome unfavorable natural conditions. It has helped develop the country's agriculture by increasing the area of cultivated land by about 30%.
Oxford Junior Encyclopedia (Volume 8)