Aswan Dam
| Aswan Dam Old Aswan Dam |
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| Coordinates | 24 ° 2 ′ 0 ″ N , 32 ° 52 ′ 0 ″ E | ||||||||
| Data on the structure | |||||||||
| Lock type: | Gravity dam | ||||||||
| Construction time: | 1898-1902, 1907-1912, 1929-1934 | ||||||||
| Height of the barrier structure : | 21.5 m → 26.5 m → 35.5 m | ||||||||
| Crown length: | 1965 m | ||||||||
| Crown width: | 9 m | ||||||||
| Power plant output: | 592 MW | ||||||||
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The Aswan Dam (also age Aswan Dam , English Aswan Low Dam ) is a completed in 1902 and 1912 and 1934 increased dam on the Nile above Aswan and below the Aswan Dam ( Aswan High Dam ) in Egypt .
The Aswan dam, together with the Asyut dam , which was also completed in 1902 and located approx. 540 km downstream, served to supply large areas of Egyptian agriculture with water even outside the flood of the Nile. After the Delta Barrages, they were the first major project to convert seasonal irrigation in flood basins, which is dependent on the Nile flood, to year-round canal irrigation .
The Aswan Dam was the largest in the world when it was completed. Their hydropower plant , installed in 1934, was the first in Egypt. With the construction of the Aswan High Dam in 1971, it largely lost its importance. Today it is mainly used to generate electricity and as a road link across the Nile.
description
The Aswan Dam is a gravity dam with a straight floor plan and a 1965 m long dam crest. The dam wall was originally 21.5 m high; it was 24.5 m wide at the base and 7 m wide at the crown. Between 1907 and 1912 it was increased to 26.5 m and from 1929 to 1934 to 35.5 m. It consists of granite - stone blocks with a core of rubble masonry . Today a two-lane road leads over the now 9.42 m wide dam crest, which offers the shortest route between Aswan and the airport.
The Aswan dam wall had 140 bottom outlets with 14 m² each and 40 higher arranged outlets with 7 m² each, which were operated by a large portal crane on the dam crest. The pillars between the culverts were 5 m thick. Support pillars 10 m wide stood between groups of ten drains each. A 1600 m long shipping channel and a lock with four chambers measuring 75 mx 9.5 m were installed on the west side . The lock gates, based on the model of the Panama Canal, are between 9 and 19 m high.
During the rising tide, 15,080 m³ / s of water including the Nile mud could pass. As soon as the water became clearer, the gates were largely closed, so that a storage volume of 1000 million m³ (last of 5000 million m³) accumulated by March / April, which was drained during the low water period from May to July to fill the irrigation channels has been.
The Aswan dam led to the flooding of the sections of the First Cataract above Aswan . Shipping on the Nile was able to overcome the dam and the cataract through the lock and sail unhindered to Wadi Halfa . While the height of the original dam wall was limited with regard to the temples on the island of Philae , the later heights of the dam wall also flooded the island, the temples of which were finally relocated to a neighboring, higher island from 1977 to 1980.
The Aswan I and Aswan II power plants are located in the rocks of the western bank and on the underwater side .
history
prehistory
The Arab scholar Abu Ali al-Hasan ibn al-Haitham ( Alhazen ), who worked at the court of Caliph Al-Hakim in Cairo around 1011, is said to have had the idea of regulating the Nile by a dam near Aswan, but this was not implemented.
In modern times, with the construction of the Delta Barrages ordered by Muhammad Ali Pascha (1805–1848 Viceroy of Egypt), irrigation of the canals independent of the Nile flood was introduced in the Nile Delta and used for the cultivation of cotton . Ismail Pasha (1863–1879 viceroy) had the 320 km long Ibrahimiyya Canal , which began in Asyut and was completed in 1873, built, which led the as yet unregulated Nile water with numerous side canals, particularly to the viceroy's sugar cane fields.
planning
Even during the British rehabilitation of the Delta Barrages , the possibility of enormously expanding the year-round irrigated fields became apparent. For this, however, a sufficient storage volume had to be created in order to be able to channel enough water into the canals even during the low water period from May to July.
In their first study in 1894, William Willcocks and William Edmund Garstin came to the conclusion that only a dam on the rocky subsoil of the First Cataract near Aswan could be considered. In order to prevent the reservoir from being filled with sediments in the shortest possible time, the dam had to have so many culverts that the flood could pass almost unhindered. For a project of this type and size, apart from the Delta Barrages, there was no model. Nevertheless, a technical commission headed by Benjamin Baker approved the plans unconditionally. But she pointed to the flooding of the temples of Philae associated with the dam. To avoid them, the commission suggested dismantling the temples and moving them to a higher island. The government decided on a dam with a reduced storage target of only 20 m above the underwater.
construction
However, the plans remained in place until Sir Ernest Cassel provided funding in 1898. The Aswan dam was then built by Sir John Aird & Co. together with the Asyut dam, which is about 540 km downstream . Deputy Building Minister William Gerstin acted as the client, Benjamin Baker was the consulting engineer. The Asyut weir was used for the regulated discharge of water from the Nile into the Ibrahimiyya Canal, which begins there, and to the fields that it irrigated and extends around 350 km to the north.
The foundation stone was laid on February 12, 1899 in the presence of the Duke of Connaught . Up to 23,000 workers were employed on both construction sites. The opening ceremony took place on December 10, 1902, in the presence of the Duke of Connaught and his wife.
Follow-up time
Immediately after the opening, all available water quantities were allocated. The coveted conversion of additional areas from seasonal irrigation in flood basins to year-round canal irrigation was hardly possible. The world's largest structure of this type at the time turned out to be too small. It was therefore increased for the first time between 1907 and 1912. For this purpose, a 5 m thick wall was placed in front of the existing dam on the underwater side so that a 5–15 cm wide gap remained open. Only after the temperature of the new wall had adjusted to that of the existing wall in the following two years, the gap was grouted with mortar. Then the uniform elevation of the dam was built on. In 1934 the dam was increased again so that the storage volume was about five times as large as it was originally. In addition, the dam received the first Egyptian hydropower plant at this time .
Even after it was raised, the old Aswan dam was only able to store sufficient water for the low water period of the respective year. However, their storage volume was too small to compensate for a low tide or even to bridge two years with particularly low water levels. This led to the construction of the Aswan High Dam, with which enough water can be dammed up to compensate for a minimum water flow that is expected to occur once every hundred years on a statistical average. Since its construction between 1960 and 1971, the old Aswan dam has largely lost its function. To relieve the dam, the water level was lowered again a little.
Hydroelectric power plant
The two hydropower plants have a total installed capacity of 592 MW . The first power plant has seven turbines of 46 MW each and a total output of 322 MW. It was put into operation in 1960. The second power plant has four turbines of 67.5 MW each and a total output of 270 MW. It was put into operation in 1985.
See also
Web links
Individual evidence
- ^ A b c William Willcocks, James Ireland Craig: Egyptian Irrigation . Volume I ; Egyptian irrigation . Volume II. 3rd edition. Spon, London / New York 1913.
- ^ O. Schulze: The dams of the Nile valley. In: Zeitschrift für Bauwesen, Volume 1, Issue VII – IX, 1900, Sp. 361, 373 ( digitized version ) and Atlas , sheet 50 ( digitized version on digital.zlb.de)
- ^ Greg Shapland: Rivers of Discord: International Water Disputes in the Middle East. C. Hurst & Co., London 1997, ISBN 1-85065-214-7 , p. 64. ( excerpts on Google books )
- ^ A b c d e William Willcocks, James Ireland Craig: Egyptian Irrigation . Volume II. 3rd edition. Spon, London / New York 1913. pp. 678 f
- ↑ Hydropower plants on the website of the Deutsches Museum, Munich
- ^ A b Maurice Zimmermann: Achèvement des grands barrages du Nil. In: Annales de Géographie, Volume 12, No. 62, 1903, pp. 191–192. (on Persee, Revues Scientifiques. PDF, 269 kB)
- ^ Roshdi Rashed: A Polymath in the 10th Century . In: Science . tape 297 , no. 5582 , February 8, 2002, p. 773-773 , doi : 10.1126 / science.1074591 , PMID 12161634 .
- ^ Major Robert Hanbury Brown: The Delta Barrage of Lower Egypt . National Printing Department, Cairo 1902 ( digitized from archive.org ).
- ↑ Willcocks and Craig name sediment transports in the Nile of 11.44 and 11.95 tons per second for August and September and 85 million tons per year ( Egyptian Irrigation , Volume II, p. 679)
- ^ Aswan Dam 1 Hydroelectric Station Egypt. Global Energy Observatory, accessed September 28, 2017 .
- ^ Aswan Dam 2 Hydroelectric Station Egypt. Global Energy Observatory, accessed September 28, 2017 .