The river Nile is the major source of water for Egypt . Since antiquity, the Egyptians, realizing the importance of the Nile, have established annual storing projects like Aswan Reservoir and Jabal Al-Awlyaa Reservoir on the Nile to control the changing river yield. Regulators were built to regulate irrigation through different river reaches. However, annual storing was no more than a partial solution for Nile control. The river yield differs largely from year to year; for it may reach 151 billiard cubic meters or fall down to 42 milliard cubic meters annually. Such huge disparity makes dependence on annual storage an extremely dangerous matter for it may subject arable lands to be waste in the low-yield years. Therefore there arose a trend to constructing a colossal dam on the Nile to save water in high-yield years to be used in low-yield years.
The High Dam Location
The site of the High Dam was chosen to be in its current place which is 6.5 km. south of Aswan Reservoir owing to the relative narrowness of the Nile stream in this location.
The High Dam Components :
The Dam Body
Following numerous international researches and studies, the High Dam was designed to be an aggregate dam that is equipped with a solid core from silt and a cutoff vertical barrier.
Level of the Dam Top ......................................... 85 m.
Level of the Dam Top ......................................... 196 m.
Dam Length at the Top.........................................3830 m.
Dam Length in the Nile 's Main Stream....................520 m.
Width of Dam Base..............................................980 m.
Dam Width at Top................................................40m.
Depth of Vertical Injection Curtain..........................170m.
Storage Lake
Water is kept in front of the High Dam in a large artificial lake whose characteristics are as follows:
Lake Length.......................................500 km.
Average Lake Width...........................10km.
Total Storage Capacity........................162 milliard cubic meter.
Dead Storage Capacity.........................32 milliard cubic meter.
Toshka Spillway Canal
Water exceeding the level of 178.000 meters in Naser Lake is discharged to the natural depression known as Toshka Depression west of the Nile via a canal connecting Naser Lake and Toshka Depression through khor Toshka.
The hydraulic specifications of the Canal Sector are as follows:
Canal Length........................................22 km.
Bottom width at Intake.........................750 m.
Bottom width at Tailescape...................275 m.
Bottom Level at Intake.........................178 m.
Bottom Declination..............................15cm./km.
Maximum Canal Discharge...................250 million cubic meter/day.
Diversion Canal
The Diversion Canal was drilled in the eastern bank of the Nile to pass the required discharges from downstream the dam to upstream. It comprises an open upstream canal connected to an open downstream canal through the six main tunnels underlying the right side of the dam.
Upstream Canal Length.......................................1150m.
Upstream Canal Width at the Intake....................50m.
Upstream Canal Width at the Tailescape..............230m.
Downstream Canal Length..................................485m.
Downstream Canal Width at the Intake...............278.5 m.
Downstream Canal Width at the Tailescape.........40m.
Tunnels
The Upstream Canal is connected to the Downstream Canal through six main tunnels. The tunnels are lined with reinforced concrete and are controlled by gates operating by an electrical lifter.
Average Tunnels Length.......................282 m.
Tunnel Diameter.................................15m.
Maximal Tunnel Discharge....................11.000 cubic meter/second.
Power Station
The Power station lies at the exits of the tunnels. Every tunnel is divided into two branches, each is equipped with a turbine for power generation:
Turbines Number....................................12 turbines
Turbine Capacity....................................175 kilowatt
Total Station Capacity............................ 2.1 million kilowatt
Produced Electrical Power...................... 10 milliard kilowatt hour/year.
The High Dam Financing Sources
President Jamal Abdel-Nasser nationalized the Suez Canal Corporation on 26 July 1956 so that the Canal's revenues would be dedicated to finance the High Dam after the World Bank withdrew its offer to finance the project owing to imperialistic pressures exerted by Britain and the United States of America . The Soviet Union lent Egypt two loans with a sum of 113.2 Million Egyptian Pounds as a funding for the High Dam. Total costs of constructing the High Dam and the Power Station reached 45 million Egyptian Pounds. The High Dam is considered one of the projects producing extremely high economic proceeds if compared with other similar international projects. Returns of ten years - since the dam was established - amounted to at least twenty times of the Project's expenditure.
The High Dam Construction Period
Work in constructing the High Dam started on 9 January 1960. Implementation of the first phase was completed on 16 May 1964. Completion of the second phase was on 15 January 1971.
The High Dam Economical Benefits
• Increase Egypt 's share of Nile water which became 55.5 milliard cubic meter annually.
• Increase the agricultural area in Egypt to 1.2 million feddans.
• Change 970 thousand feddans from basin irrigation system to permanent irrigation system which led to an increase in productivity per feddan.
• Expand cultivating rice to 700 thousand feddans annually.
• Improve river navigation round the year.
• Generate new electrical power amounting to 10 milliard kilowatt/year that was used in lighting villages and cities and for purposes of agricultural and industrial expansion.
• Protect the country from drought in low-yield years as the case in the period from 1979 to 1987.
• Protect Egypt from high floods dangers like the devastating flood that occurred in 1964 and the most dangerous flood in 1975.
Water Flow into Toshka Spillway
Water was released into Toshka Spillway for the first time on 15/10/1996 where water level upstream reached 178.55m.
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