Aswan High Dam
| Aswan High Dam | |||||||||
|---|---|---|---|---|---|---|---|---|---|
 |
|||||||||
|
|||||||||
|
|||||||||
| Coordinates | 23 ° 58 '14 " N , 32 ° 52' 40" E | ||||||||
| Data on the structure | |||||||||
| Construction time: | 1960-1971 | ||||||||
| Height of the barrier structure : | 111 m | ||||||||
| Building volume: | 44.3 million m³ | ||||||||
| Crown length: | 3,830 m | ||||||||
| Crown width: | 40 m | ||||||||
| Base width: | 980 m | ||||||||
| Power plant output: | 2,100 MW | ||||||||
| Data on the reservoir | |||||||||
| Altitude (at congestion destination ) | 183 m | ||||||||
| Water surface | 5,248 (5,860 / 5,500 / 6,000?) Km² | ||||||||
| Storage space | 168.90 km³ | ||||||||
The Aswan High Dam (also known as the Aswan High Dam ), called es-Sadd el-Ali ( Arabic السد العالي, DMG as-Sadd al-ʿālī 'high dam'), is located in southern Egypt ( Upper Egypt ) about 13 kilometers south or upstream of the city of Aswan and dams the Nile to Lake Nasser , which extends into Sudan , where it Nubia -See is called. The reservoir has a capacity of 135 to 169 cubic kilometers of water.
Old dam wall
The old dam is located about seven kilometers southwest of Aswan . It was built between 1898 and 1902 by the company John Aird & Co. to a design by William Willcocks and plans by Benjamin Baker and William Edmund Garstin . The aim was to regulate the water mass of the Nile, especially during the annual flood, in such a way that sufficient water was available for the fields that had already been switched to year-round canal irrigation in the subsequent low water phase . The old dam was put into operation on December 10, 1902.
The structure consists of granite blocks and quarry stone masonry, is 35 meters wide at the bottom, 9 meters wide at the crown and around 1965 meters long. In the years 1907-1912 and 1929-1933 the dam was increased to 36 meters. The water level could be regulated through 180 passages and the very fertile Nile mud , which is important for Egyptian agriculture , was able to pass through the barrier.
The largest structure of its kind in the world at the time turned out to be too small. Despite the two subsequent increases to a storage volume of 5000 million m³ (five cubic kilometers), it was hardly able to meet the need for year-round canal irrigation. It was not able to compensate for a low tide or even to bridge two years with particularly low water levels - events that had repeatedly led to great famines since the Pharaonic times and which would have had catastrophic consequences for the population, which had increased many times over.
New dam
prehistory
As early as 1900, the British were considering how low water levels could be compensated for and additional water supplied to the fields in Egypt. Already at that time, a damming of Lake Tana and Lake Victoria, a canal along the Sudds and a reservoir in the White Nile above Khartoum were considered. However, these measures met with various opposition, only the Jebel-Aulia-Damm was built and put into operation in 1937 to compensate for low water levels.
Harold Edwin Hurst took up these ideas again. In 1915, as head of the natural sciences department of the Ministry of Public Works, he began researching and documenting the hydrological conditions of the Nile and its tributaries for decades. Based on this huge collection of data, shortly before his retirement in 1946, he presented a concept to Century Storage with which a low water period, as it is expected to occur on a statistical average once every hundred years, is bridged by the measures mentioned on the two source rivers and thereby immense Egypt Damage could be saved.
When determining the storage volume required for this, Hurst discovered the phenomenon that was later named after him, that his empirical data clearly resulted in a larger volume than would have been expected from the theoretical calculation methods used at the time. Hurst developed his findings on this phenomenon in publications in 1951, 1952 and 1965, which led to adjustments in mathematical statistics and prompted Benoît Mandelbrot to work on the Hurst phenomenon, which ultimately led to the Hurst exponent .
Planning, financing, construction
Adrian Daninos developed the idea for a project for a single large dam above Aswan in 1947 and presented it to the Egyptian government under King Faruq the following year . However, this initially showed no interest in implementation. It was only after Faruq's fall in 1952 that the proposals received attention. Muhammad Nagib and Gamal Abdel Nasser quickly decided on the idea of a large dam that could be controlled solely by Egypt, instead of several reservoirs on the territories of other states.
In the meantime, Hurst had determined the necessary storage volume of 37 km³ for irrigation during one year, 90 km³ for storage ( Century Storage ) and 30 km³ for provision for sedimentation losses. Later the total volume was expanded by a further 6 km³ to a total of 163 km³. Large-scale measurements, including by air, have shown that this volume is at a maximum storage height of 183 m above sea level. d. M. was available. As it turned out, it was possible to dispense with an additional volume for the safety reserve that is usual with dams to protect against extreme floods, since a wadi to the Toshka Depression about 260 km upstream could serve as a flood relief channel.
In 1954 there were negotiations about an offer from Hochtief and Rheinstahl Union Bridge Construction for a rock embankment and a power plant with eight turbines. However, there was no funding for the project, which was estimated to total 2.1 billion DM , and which should also include a nitrogen factory. The USA and Great Britain announced a contribution of 70 million US dollars in December 1955. The USA withdrew their willingness seven months later because the Egyptian government officially recognized the People's Republic of China in 1956 and its neutrality policy aroused the displeasure of the USA. Financing by the World Bank was therefore no longer up for discussion. Nasser then nationalized the Suez Canal , among other things in order to be able to finance the construction of the dam, survived the Suez crisis and received the support of the Soviet Union , which tried to gain influence on the African continent and regarded the dam as a prestige project, as did the Egyptian government.
Since the reservoir would also flood large parts of the Nile valley south of the national border, Egypt concluded an agreement with Sudan in 1959 : On the basis of an assumed annual inflow of 84 km³ and an evaporation of 10 km³, the remaining 74 km³ were divided between the two countries, where Egypt should be entitled to 55.5 km³ and Sudan 18.5 km³. In addition, Egypt had to bear the cost of resettling the affected population. In this context, the Khashm-el-Girba dam was built in order to give a new livelihood to the approximately 50,000 mainly Nubian inhabitants from the area of Wadi Halfa in the New Halfa project .
The roughly 50,000 inhabitants displaced from the Egyptian part of the Nile were mainly settled in Kom Ombo .
In addition to financing, the support from the Soviet Union also included the planning of the dam by the Russian Hydroproject Institute , the dispatch of around 2,000 Soviet engineers and the delivery of a large part of the construction equipment required. On the Egyptian side, Osman Ahmed Osman and his company Arab Contractors played a key role in carrying out the construction work, which employed around 30,000 workers.
On January 9, 1960, construction of the Aswan Dam began with a blast. Four years later, after completion of the first construction phase, water from the Nile was introduced for the first time to fill the reservoir. At a ceremony on May 14, 1964, President Nasser and Soviet head of state Nikita Khrushchev, as well as Presidents Abd as-Salam Arif ( Iraq ) and Abdullah as-Sallal ( Yemeni Arab Republic ) together operated a switch to blow up a sand wall, bringing the Nile in the intended pool was diverted.
The dam was completed on July 21, 1970. But it was only officially opened on January 15, 1971 by Nasser's successor Anwar el-Sadat . The filling of the reservoir, later called Lake Nasser , was not completed until 1976.
The project cost the equivalent of around 2.2 billion euros. 451 people lost their lives in connection with the construction work.
dam
The barrier structure consists of a huge gravel embankment with a clay sealing core and a concrete shell. The dam is more than 3800 meters long and 111 meters high, 980 meters at the bottom and around 40 meters wide at the top.
At the western end of the dam there is a concrete monument in the shape of a lotus flower with a centrally arranged gear wheel - as a sign of Egyptian-Soviet friendship. A viewing platform is located here at a height of 74 meters.
Hydroelectric power plant
The hydropower plant has twelve Francis turbines with a maximum output of 175 megawatts each, a total of 2100 megawatts. The electricity generated is conducted to Cairo. At the time the power plant went into operation, it provided almost half of Egypt's electricity needs, and today it still accounts for 10% of Egypt's electricity generation.
Reservoir
The approximately 500 km long reservoir is the third largest in the world in terms of content and the seventh largest in terms of area (in each case without taking Lake Victoria into account ). Since the area data vary from 5248 to 5500 and 5860 to 6000 km², it could also be the third largest reservoir. See the list of the largest reservoirs on earth .
aims
The primary goal of the construction of the Aswan High Dam was to protect Egypt, its people and its agriculture from the catastrophic consequences of prolonged periods of drought on the source rivers of the Nile, which resulted in an exceptionally low water flow in the Nile and thus extensive drying up of the irrigated fields would have had. In the same way, the Nile valley below the dam should be protected from damage from floods . Both goals were achieved. During the extreme drought from 1984 to 1985, an outflow of more than 53 km³ per year could be maintained. The high floods of 1975 and 1988 could also be intercepted without damage.
In addition, agriculture and the development of an industry should be promoted by the dam.
The dam therefore serves several purposes:
- Storage of large amounts of water in order to ensure the water supply in dry periods and control of the amount of water flowing off in order to protect the Nile land in the event of severe flooding ;
- Securing the drinking water supply;
- Power generation;
- Improving the navigability of the Nile;
- Building new industries.
In addition, it inevitably took over the function of the old Aswan dam:
- Conversion of the remaining, traditionally seasonally irrigated areas to permanent irrigation, so that instead of the traditional one harvest, two to three harvests were possible everywhere;
- Expansion of the arable land by 535,000 hectares through irrigation ;
- Expansion of rice and sugar cane cultivation to reduce expensive imports.
Relocation of the temple complex
Since the dammed water of the Nile threatened important cultural monuments of ancient Egypt, some were moved to higher elevations with the help of UNESCO . The implementation of the temple of Abu Simbel , the temple of Philae , which was already flooded by the old dam, and the facilities of Kalabsha and Amada became famous .
The following temples have been rebuilt in other countries:
- Temple of Debod in Madrid
- Temple of Dendur in the Metropolitan Museum of Art in New York
- Temple de Taphis in the Rijksmuseum van Oudheden in Leiden
- Temple of Ellesija in the Museo Egizio in Turin
The following systems have been rebuilt in the Sudan National Museum in Khartoum :
- Temple of Ramses II from Aksha
- Temple of Hatshepsut from Buhen
- Khnum temple from Kumma
- Burial chamber of the Nubian prince Djehuti-hotep from Dibeira
- Temple of Dedun and Sesostris III. from Semna
- Granite columns of Faras Cathedral
- Part of the murals in Faras Cathedral; the other part is in the National Museum in Warsaw .
Many other cultural assets sank in the floods.
Problems
The relocation of the mostly Nubian farmers has wiped out much of the Nubian culture.
Due to the lack of nutrients in the water, the fish population from Aswan has decreased drastically. In the eastern Mediterranean off the Egyptian coast, too , fish catches fell by almost half after the construction of the dam, but have recovered somewhat. It remains to be seen to what extent the decline in yields is solely due to the conversion of agricultural methods in Egypt or whether it is an aspect of the general overfishing of the Mediterranean . On the other hand, the fish population in Lake Nasser developed.
It is also lamented that the fertile Nile mud is lacking for agriculture downstream. However, since the conversion of irrigation methods on the Nile to year-round irrigation canals, which began under Muhammad Ali Pasha (1805–1848 Viceroy of Egypt) , the Nile mud has played an increasingly minor role. When the Aswan Dam was built, it was consciously accepted that the mud would remain in the reservoir.
Silting , which is also frequently mentioned, plays a role in reservoirs on the Blue Nile, but is not relevant for the Aswan Dam, as it was taken into account when determining the storage volume and the half-way through the use of the reservoir is not expected for hundreds of years. The Nile mud has been held back there since the construction of the Merowe Dam in Sudan.
There were fears that downstream, and especially in the Nile Delta, erosion could be a major problem, as the lack of Nile mud that was otherwise transported by the river would wash away farmland and damage bank reinforcements. However, most of the water in the Nile is channeled through irrigation canals, the maintenance of which has been made easier by the absence of sediments.
The fish stocks in the brackish water of the Nile Delta, where a large part of the Egyptian fish were caught, were damaged by the penetrating salty seawater. In addition, there is significant erosion along the coasts of the Nile Delta, as the sand washed into the sea by the Nile is missing. Appropriate measures must be taken to counteract erosion.
The danger of schistosomiasis, which has always existed in Egypt, especially in the Nile Delta, is contained by a wide variety of measures. The water snails that transmit the disease do not seem to be able to live in Lake Nasser.
Due to the rising groundwater level , ancient monuments are acutely threatened.
See also
- List of power plants in Egypt
- List of dams in the world (Egypt)
- List of dams on the Nile
- List of the largest dams on earth
- List of the largest reservoirs on earth
- List of the largest hydroelectric plants in the world
literature
- Günter Meyer: The high dam near Aswan and its consequences: cliché versus reality . In: Günter Meyer (ed.): The Arab world in the mirror of cultural geography . Publications of the Center for Research on the Arab World (ZEFAW) Volume 1, Mainz 2004, pp. 178–185.
- Heinz Schamp (1983) Sadd el-Ali, the high dam of Aswan I - facts, goals, consequences. Geosciences in our time; 1, 2; 51-59; doi : 10.2312 / geosciences.1983.1.51 .
- Heinz Schamp (1983) Sadd el-Ali, the high dam of Aswan II. Geosciences in our time; 1, 3; 73-85; doi : 10.2312 / geosciences.1983.1.73 .
Web links
Individual evidence
- ↑ Construction of the Aswan Dam in 1902
- ^ William Willcocks, James Ireland Craig: Egyptian Irrigation Volume I ; Egyptian Irrigation Volume II. 3rd edition. Spon, London / New York 1913, p. 676 f.
- ^ A b c John V. Sutcliffe, Yvonne P. Parks: The Hydrology of the Nile . International Association of Hydrological Sciences, Wallingford 1999, ISBN 9781901502756 , p. 154 f. ( PDF, 222 kB )
- ↑ Benoît B. Mandelbrot, JR Wallis: Noah, Joseph and operational hydrology. Wat.Resour.Res. 4, 909-918. 1968.
- ↑ Aswan Dam, a dream for a thousand years ( Memento of May 4, 2014 in the Internet Archive ) in Der Spiegel No. 36/1954 of September 1, 1954.
- ↑ Jul 19, 1956: United States withdraws offer of aid for Aswan Dam. On This Day in History .
- ^ January 9, 1960 - Construction of the Aswan Dam begins. Video from the historical film archive.
- ↑ BBC : On This Day, May 14 1964: Nasser and Khrushchev divert the Nile
- ↑ History : This Day in History, July 21 1940: Aswan High Dam completed
- ↑ Memories of a dam, a high dam ... ( Memento from September 6, 2014 in the Internet Archive ) Article from January 10, 2010 on Egypt Independent .
- ↑ Seleshi Bekele Awulachew, Vladimir Smakhtin, David Molden, Don Pede: The Nile River Basin, Water, Agriculture, Governance and Livelihoods. International Water Management Institute, 2012 ( PDF, 59 kB )
- ↑ a b M. A. Abu-Zeid, FZ El-Shibini: Egypt's High Aswan Dam. ( Memento from July 20, 2011 in the Internet Archive ) Water Resources Development, Vol. 13, No. 2, 1997, pp. 209-217. (PDF, 186 kB)
- ↑ Ahmed Saleh (Ed.): Assessment of the current state of the Nile Basin Reservoir Sedimentation Scheme. ( Memento from October 9, 2010 in the Internet Archive ) Nile Basin Capacity Building Network 'NBCBN', 2005 (PDF, 55 kB)
- ^ Hermann A. Schlögl : The old Egypt: History and culture from the early days to Cleopatra. Beck, Frankfurt am Main 2006, ISBN 3-406-54988-8 , p. 18.