Hoover Dam

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Hoover Dam
Hoover Dam
Hoover Dam
Tributaries: Colorado River
Drain: Colorado River
Larger cities on the shore: Boulder City
Major cities nearby: Las Vegas
Hoover Dam (USA)
Hoover Dam
Coordinates 36 ° 0 ′ 56 "  N , 114 ° 44 ′ 16"  W Coordinates: 36 ° 0 ′ 56 "  N , 114 ° 44 ′ 16"  W
Data on the structure
Construction time: 1931-1935
Height of the barrier structure : 221.46 m
Height above the river bed : 180 m
Building volume: 2.6 million m³
Crown length: 379.2 m
Crown width: 14 m
Power plant output: 2,080 MW
Data on the reservoir
Altitude (at congestion destination ) 372.28 m
Water surface 639 km²dep1
Reservoir length 170 kmdep1
Storage space 35,154 million m³
Hoover dam.jpg
The Hoover Dam
Presa Hoover3013.JPG
Water intake towers
Inside Hooverdam.jpg
Generators of the Hoover Dam
Firing channel in Hoover Reservoir, Arizona 2015.jpg
Weft gutter (overflow) of the Hoover Reservoir, 2015
HooverDamm.jpg
View from the dam into the canyon and the Mike O'Callaghan-Pat Tillman Memorial Bridge

The Hoover Dam is a dam on the border between the US states of Nevada and Arizona , about 45 kilometers east-southeast of Las Vegas in the Black Canyon. His dam dams the Colorado River , which forms the border between Arizona and Nevada here, to Lake Mead . The dammed lake has an area of ​​63,900 hectares (other information: 69,000 hectares), a length of around 170 km and a maximum depth of around 180 meters. With its storage capacity of around 35 billion cubic meters, it is the largest reservoir in the USA.

The main purpose of the dam is to provide controlled water delivery in Arizona, Nevada, and California. Prior to construction, regular flooding of the Colorado and periods of drought affected the lives of settlers in the southwestern states, particularly in agriculture. Another purpose of the dam is to generate electrical energy. The project finances itself through the sale of this energy and bears the ongoing maintenance costs itself. The water flow is regulated depending on the amount of water required downstream.

Construction of the dam

The Hoover dam was built between 1931 and 1935 as an arched weight wall with a height of 221 meters and a crown width of about 14 meters. The bottom width is 201 meters. The dam consists of around 2.6 million cubic meters of concrete and 43,500 tons of steel. It was not cast in one piece, but made from many individual trapezoidal, 1.50 meter high concrete blocks. One-inch-thick water pipes were tied into the blocks to circulate chilled water. In this way, the heat of hydration generated during the setting of the concrete could be reduced, thus reducing the formation of cracks. If the wall had been cast as one block, it would have taken more than 100 years for the cooling process to finally subside. The cooling systems were able to produce 1,000 tons of ice a day.

Photo from 1942

The then very new method of glass fiber reinforcement was used to improve strength . The concreting lasted from June 1933 to March 1935. In order to dry out the construction site, two tunnels were driven through the rock walls of the gorge on each side of the river and the Colorado was passed through them. The diameter of the tunnels was 17 meters, each tunnel was 1,200 meters long, with about 14 meters being excavated per day during the construction period. Until the Vajont dam was built in Italy in 1961, the dam was the tallest barrier in the world. The dam cost $ 49 million to build. $ 165 million flowed into the overall Boulder Canyon project, which includes the Hoover Dam, Imperial Dam and American Canal. During the construction of the dam, 96 of the approximately 5,000 workers involved in construction died as a result of work accidents , heat strokes or exhaustion. A total of around 16,000 people worked on realizing the project.

The first generator started delivering energy on October 26, 1936. Then the others were gradually put into operation.

Naming

The dam and its dam was named after Herbert C. Hoover , the 31st President of the USA. The dam was originally supposed to be built in Boulder Canyon , so the project began with the designation Boulder Dam , which was still used in the official instruction to start construction on July 7, 1930 by Ray Lyman Wilbur , Hoover's Secretary of the Interior . Ultimately, however, the decision was made to build the structure in the Black Canyon, about 16 km upstream , because the rocky subsoil there allowed a higher dam wall; At the beginning of the official construction phase, Wilbur ensured that the project was renamed Hoover Dam . Herbert C. Hoover stood for re-election as president at this point; the connection of his name with this construction project, which during the Great Depression created jobs several thousand should help to increase his election chances.

Hoover did not win the election, however, and on May 8, 1933, Harold L. Ickes , the interior secretary of the new President Franklin D. Roosevelt , arranged for the project to be renamed Boulder Dam again . Under President Harry S. Truman , this step was reversed again: On April 30, 1947, Truman ordered that the dam should again bear the name of the President under whose tenure the construction project was started.

In German, the terms Hoover-Damm , Hoover-Staudamm and Hoover-Talsperre as well as, with regard to the construction, Hoover-dam wall are also found as translations .

power

The electrical output of the generators driven by the 17 turbines is around 2,080  MW . About 56 percent of the energy produced is supplied to southern California. High-voltage pylons had to be built as a crooked construction on the edge of the vertically sloping gorge . The 2,080 megawatts of output were only achieved after an increase in output. The original turbines only had an output of 80 megawatts each; Between 1986 and 1993 new turbines with an output of 130 megawatts each were installed. Today's output consists of 13 turbines with 130 MW each, two 127 MW, one 68.5 MW and one 61.5 MW turbine. Each of these new turbines is made of 35 tons of stainless steel, has a diameter of 5 meters and a height of 2 meters. The maximum of 100 cubic meters of water flow per second (m³ / s) ensure a speed of 180 revolutions per minute. The dam generates around 4 billion kWh of electricity annually.

Ecological side effects

The actually warm Colorado River with a high sediment load (cloudy-brown color) loses its original character due to the damming. In the reservoir, the fine particles of the dammed up river sediment on the bottom of the reservoir. The turbined water is usually taken from greater depths, where the water is significantly colder due to the stratification of the lake. As a result, the Colorado River continues to flow through the canyon as a clearer, cooler river in the course of the underwater. This displaces native fish of the Colorado River; some are threatened with extinction (e.g. Ptychocheilus lucius ). Another ecological effect of the dam is the homogeneous runoff regime. Since naturally occurring floods are buffered by the dam, there are no clearing processes in the river bed. This colmatises ("clogs") the water bed , which, for example, hinders or prevents the development of certain fish eggs. The lack of redistribution of rocks and the thus suppressed dynamics of this system have a lasting effect on flora and fauna. To alleviate this problem, an artificial flood is created every few years if there is sufficient water capacity.

Others

The Hoover Dam was added to the List of Historic Civil Engineering Landmarks by the American Society of Civil Engineers in 1984. In August 1985 it was given the status of a National Historic Landmark .

The city of Las Vegas owes its current appearance to the construction of the dam, because only through the construction project, which was around 50 km away, for which thousands of workers were needed, did the small desert settlement founded in 1905 become today's gaming metropolis. In Boulder City , which was built especially for the workers and their families , gambling and alcohol were forbidden, so that many of the workers were drawn to nearby Las Vegas in their free time, which in a short period of time had more and more bars and casinos to offer.

The border between the states of Arizona and Nevada runs exactly in the middle of the dam. As a result, the eastern half of the Hoover Dam falls in the time zone of Mountain Time (UTC-7 in Arizona), the western half in the zone of Pacific Time (UTC-8 in Nevada). The time difference of one hour can be read on two clocks located on the front extraction towers - in summer, however, the times displayed are the same because there is no daylight saving time in Arizona.

To relax the traffic, the " Mike O'Callaghan-Pat Tillman Memorial Bridge " (US 93) was built, which was originally supposed to be finished in June 2008. In September 2006, two construction cranes overturned due to strong winds, so that completion was delayed. Traffic was opened on October 19, 2010 at 10 p.m. local time.

media

  • World wonder of technology. The Hoover Dam. Documentation, GBR, 2004, 45 min., Written and directed by Mark Everest, production: BBC , first broadcast: January 3, 2005
  • The Hoover Dam. Documentation, 44 min., Production N24 , first broadcast: August 19, 2009, and by N24
  • The Hoover Dam. Documentation, 2004, 14:29 min., Milestones in science and technology, episode 67

The Hoover Dam is a popular setting in films such as Superman , Transformers , Universal Soldier and San Andreas , as well as many computer games such as Fallout: New Vegas , Duke Nukem Forever , Rainbow Six Vegas , GTA San Andreas and Freeciv . It also served as a model for the dam wall of the fictional Black Mesa Research Facility in the computer games Half Life and Black Mesa .

See also

literature

Web links

Commons : Hoover Dam  - collection of pictures, videos and audio files

Individual evidence

  1. ↑ a b c Hoover Dam Answers to FAQ's, Trivia and Facts. In: SunsetCities.com
  2. ^ Construction History of Hoover Dam - A Brief Overview of Hoover Dam Construction. In: arizona-leisure.com
  3. ↑ Hoover Dam 75th Anniversary History Symposium  ( page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. , Google Books, accessed November 9, 2011@1@ 2Template: Dead Link / books.google.co.uk  
  4. ↑ Bureau of Reclamation: Hoover Dam chronology ( Memento of May 13, 2009 in the Internet Archive ), accessed on October 7, 2011
  5. ↑ Hoover Dam FAQ's and Answers, Hydropower at Hoover Dam ( Memento of the original from March 23, 2010 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. In: usbr.gov @1@ 2Template: Webachiv / IABot / www.usbr.gov
  6. ↑ this corresponds to an average turbine output of 456.6 megawatts.
  7. ↑ Listing of National Historic Landmarks by State: Nevada. National Park Service , accessed August 17, 2019.
  8. ↑ table of contents. In: 3sat.de , accessed on January 15, 2012
  9. ↑ Table of contents ( Memento of the original from February 20, 2010 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.n24.de
  10. ↑ Video stream ( Memento of the original from June 22, 2011 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / mediencenter.n24.de