Hoover Dam

The Hoover Dam ( English Hoover Dam, originally known as Boulder Dam ) is located on the border between the U.S. states of Nevada and Arizona, about 50 kilometers southeast of Las Vegas in the Black Canyon. Your shut-off dammed the Colorado River, which forms the border between Arizona and Nevada here on to Lake Mead. The pent-up lake has an area of ​​63,900 hectares ( other indication: 69,000 hectares) to a length of about 170 km and a maximum depth of about 180 meters. With its storage capacity of about 35 billion cubic meters, it is the largest reservoir in the United States.

The main purpose of the dam is the controlled release of water in Arizona, Nevada and California. Before the construction of regular flooding of the Colorado and droughts affected the lives of the settlers in the southwestern states, especially in agriculture. Another purpose of the dam is the generation of electrical energy. Through the sale of electricity, the project refinanced and pay the ongoing maintenance costs themselves, the water flow is regulated depending on the amount of water needed downstream. Thus, the amount of electricity produced depends on the water withdrawal.

Translation " Hoover Dam "

Although it is in the shut-off of the Hoover Dam is a dam (English river dam ), the English name " Hoover Dam" mostly wrong with " Hoover Dam " or " Hoover Dam " (English embankment dam) is translated. The distinction depends on the materials used.

Construction of the dam

The Hoover Dam was built 1931-1935 as arch-gravity dam with a height of 221 ​​meters and a crown width of about 14 meters. The bottom width is 201 meters. The dam consists of approximately 2.6 million cubic meters of concrete and 43,500 tons of steel. She was not cast in one piece, but created from many individual, trapezoidal, 1.50 meter high concrete blocks. In the blocks one inch were included strong water pipes, circulating through the chilled water. Thus, the setting of the concrete produced during the heat could be derived much faster. Had poured the wall as a block, they would have been necessary to cool and final decay of the curing process more than 100 years. The cooling systems were to produce 1000 tons of ice in a position every day. To improve the strength, the then very new method of glass fiber reinforcement was used. Concreting lasted from June 1933 to March 1935. To dry out the building site, two tunnels were on each side of the river forced through the walls of the gorge and the Colorado passed through this. The diameter of the tunnel was 17 meters, each tunnel has a length of 1,200 meters, with about 14 meters were excavated per day during the construction of this tunnel. The dam was to the building of Alvaro Obregon Dam in Guanajuato, Mexico, in 1946, the highest shut-off of the earth. The construction of the dam cost $ 49 million. In the overall project Boulder Canyon to the Imperial Dam and even American Canal include in addition to the Hoover Dam, fins $ 165 million. In the construction of the dam 96 of about 5,000 working at the construction workers died as a result of industrial accidents, heat stroke or exhaustion. In total, about 16,000 people worked on the realization of the project.

The first generator supplied from the October 26, 1936 energy. The addition was made ​​gradually into operation.

Naming

The dam and her dam was named after Herbert C. Hoover, 31st President of the United States. After the dam was originally in the "Boulder Canyon " ( 16 km downstream) should be built, but was eventually built for structural reasons in the " Black Canyon " ( the local bedrock allowed a higher dam ), the project began with the name " Boulder Dam " that was still used in the official statement for the start of construction of 7 July 1930 Ray Lyman Wilbur, the Home Secretary Hoover. At the beginning of the official construction phase but Wilbur made ​​sure that the project " Hoover Dam" has been renamed. Herbert C. Hoover stood at this time for re-election as President; the connection of this construction project, which during the Great Depression created several thousand jobs, with the name Hoover should help to increase his chances of re-election.

Hoover but not won the election and on May 8, 1933 Harold L. Ickes made ​​, the Minister of the Interior of the new President Franklin D. Roosevelt, that the project back bore the name "Boulder Dam". Only under President Harry S. Truman, this step was undone. On April 30, 1947, led Truman that the dam again bore the name of the President, under whose tenure the building project was started.

Performance

The electrical output of the driven out of the 17 turbines generators is about 2,080 MW. About 56 percent of the energy generated will be delivered to Southern California. Pylons had to be built as an inclined structure at the edge of the vertical drop of the gorge. However, the 2,080 megawatts of power were achieved only after an increase in performance. The original turbines only reached a capacity of 80 megawatts; 1986-1993 new turbines with a capacity of 130 megawatts were installed. Today's performance is made up of 13 turbines with 130 MW, two 127 -MW, a 68.5 MW and 61.5 MW turbine together. Each of these new turbines consists 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) provide for a speed of 180 revolutions per minute. The dam produces about 4 billion kWh of electricity annually.

Ecological side effects

The really warm and with high sediment load ( dull - brown color ) equipped Colorado River loses its original character through the impoundment. The compartment the finest particles of the dammed river sediment from the lake bottom to the reservoir. Through the turbines the water is usually taken from greater depths, where the water is much colder due to the stratification of the lake. Following the Colorado River flows during the Under water as clear, cooler flow further through the canyon. This native fishes of the Colorado River are displaced; some are threatened with extinction (eg Ptychocheilus lucius). A further ecological impact of the dam is the homogeneous flow regime. Since naturally occurring floods are buffered by the dam, missing clean up operations in the river bed. This kolmatiert ( " clogs " ) the river bed, which, for example, the egg development of certain fish eggs difficult or impossible. The lack of rearrangement of rocks and the unterbundene dynamics of this system influenced the flora and fauna sustainable. To alleviate this problem every few years is to create an artificial flood with sufficient water capacity.

Others

The Hoover Dam was taken by the American Society of Civil Engineers in the List of Historic Civil Engineering Landmarks in 1984.

The city of Las Vegas owes the construction of the dam its present appearance, as were needed only by the 50 km distant construction project for the thousands of workers who became today's players metropolis from the wilderness settlement founded in 1905, small. In -built for the workers and their families Boulder City gambling and alcohol were banned, so it attracted many of the workers in their spare time to the nearby Las Vegas had to offer so within a short time, especially more and more bars and casinos.

The border between the states of Arizona and Nevada runs exactly in the middle of the dam. This has the consequence that the eastern half of the Hoover Dam in the time zone of the Mountain Time falls (UTC -7 in Arizona), the western half of the zone in the Pacific Time ( UTC-8 in Nevada). The time difference of one hour can be seen in two watches, which are located at the front taking towers, and reading - in the summer the days are the same, however, as in Arizona, no DST (Daylight Saving Time) applies.

To relax the traffic, the " Mike O'Callaghan - Pat Tillman Memorial Bridge " ( U.S. 93 ) was built, which was originally supposed to be completed in June 2008. In September 2006 due to heavy winds overturned two construction cranes, so that the completion was delayed. The traffic was released on 19 October 2010 at 22.00 local time clock.

Media

• Wonders 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 minutes, N24 production, first broadcast: August 19, 2009 and N24

The Hoover Dam is a popular Handlungsort in movies such as Transformers and Universal Soldier, as well as many computer games, such as Fallout: New Vegas, Duke Nukem Forever, Rainbow Six Vegas, GTA San Andreas and Freeciv.