Glen Canyon Dam
The Glen Canyon dam ( Glen Canyon Dam ) is an arch-gravity dam that accumulates the Colorado River in Arizona. Starting from the storage content is the resulting reservoir, Lake Powell to Lake Mead is the second largest reservoir in the United States.
The dam was designed by the Bureau of Reclamation and built from 1956 to 1964; at a cost of 187 million U.S. dollars. With 216 meters construction height (above the bedrock ), it is the fifth highest dam in the U.S.. The height above the former river bed is 178 m. The mural crown is 475 meters long with a width of 7.6 m. The wall is at the lowest point of construction 91 meters wide, the maximum width is reached at the right abutment with 106 m. The wall comprises a concrete volume of 3,750,000 m³. Because of this thickness can no longer be described as pure arch dam. Part of the water load it carries off as a gravity dam; therefore, it is as with the Hoover dam to an "arc weight ( jam ) wall ".
During construction, 4,212,551 cubic meters of sand and rock had to be moved.
Relief and collection facilities
The wall has four openings ( outlet pipes ) diameter of 2 m, can flow per second through 420 cubic meters of water.
Eight -pressure pipes ( penstocks ) with a diameter from 4.6 to 4.3 m per second lead in total 940 cubic meters of water to eight turbines ( 155,550 hp), driving the eight generators with a total capacity of 1,296 MW. Electricity from the Glen Canyon dam supplies the states of Wyoming, Colorado, Utah, New Mexico and Arizona with energy.
On both sides of the dam ever leads a relief channel ( spillway tunnel ) which tapers in diameter from 15 m to 12 m, through the rock. Through both together up to 5,890 m³ of water can be drained per second. The spillways (flood relief ) are needed only if large masses of water must be drained to lower the water level of the reservoir or to prevent flooding of the wall ( at high tide ). With a use of spillways, it was discovered that the exiting water, in contrast to the waters of Lake Powell, a distinct red coloration exhibited. When examined after the closing of the spillways, it was found that the water had led to significant erosion within the tunnel in red sandstone. To prevent further erosion at the next use, you dressed both tunnels with concrete.
The added maximum Abführvermögen the discharge and collection facilities is 5890 420 940 = 7250 m³ / s
History of the dam
The Glen Canyon dam was planned as part of the Colorado River Storage Project and constructed. Purpose of this building was the construction of a water reservoir for the water- poor states of the Southwest. At the same time electricity should be generated for the ever- growing demand. In addition, it was made possible by the dams to prevent the recurrent floods in the downstream regions.
From 1946 to 1948, the Glen Canyon of engineers and geologists of the Bureau of Reclamation has been studied to find the right place for the shut-off. The place they finally chose, united several advantages:
- The area that covered the dam, forming a basin which can hold a large amount of water.
- The walls of the gorge at this point are very steep and are very close together.
- The rock of the canyon walls and the ground is firm enough to give the necessary support to the dam.
- There was near enough sand and rock for the enormous amount of concrete that was required for the construction.
On October 15, 1956 officially started construction work on the dam. To divert the water during the construction of the Colorado River, one blew up on each side of the gorge a tunnel through the red sandstone. Thus, the actual river bed was drained in the field of construction. Since the path for vehicles was from one side of the gorge to the other more than 200 miles, was built in the immediate vicinity of the Glen Canyon Bridge, which was completed in 1959. On June 17, 1960, the concreting of the dam that were not interrupted for three years day and night and ended on September 13, 1963 began. For the construction workers employed and their families built a camp in 1957 in the immediate vicinity, which later became the city of Page. 17 construction workers died during the ten -year construction period. In 1963, then began to dam the river. From 1963, the turbines and generators were installed. The last two generators were commissioned in 1966. On October 22, opened in 1966, Lady Bird Johnson, the wife of U.S. President Lyndon B. Johnson, the dam. It took 17 years, from March 13 1963 until June 22, 1980 to fill the reservoir completely. With a maximum depth of about 171 m at the dam of Lake Powell includes 33.3 billion m³ ( = 33.3 km ³) of water and is therefore entitled under the Lake Mead is the second largest reservoir in the United States. The area of the reservoir is different claims to either 640 km ², 658 km ² and 1627 km ².
Effects on the environment
The construction of the Glen Canyon dam has far-reaching consequences for nature. By regulating the flow, the amount of transported sediment and the seasonal fluctuations of the water temperature changed. As a result, the water quality of the Colorado River has improved considerably below the dam and in the reservoir. Since settles most of the sediments in Lake Powell, the water is now blue - green and clear instead of red and muddy. This made it possible to locate various types of perch in the lake. Below the dam now rainbow trout live in the Colorado River.
On the other hand, the damming of the Colorado River has also brought significant disadvantages for the further course of the river with it, especially in the area of the Grand Canyon.
The reduced number of floods since the regulation has also reduced the size of the sand banks on the banks and allows the vegetation to encroach on the river bed. Debris accumulations that could be deposited in the mouths of the tributaries of the side because of the low water velocity, the flow close one more and the backwater areas where native species of fish, sand gradually. As a flagship species for the changes applies the fish Gila cypha, which is a protected species by the Federal government. To his protection experiments were held with the water level.
Since the construction of the dam more water was only on a few occasions drained from the reservoir than 930 m³ / s, the flow through the pressure tubes:
- On 5 March 2008 a controlled tidal wave for the purpose of studying the impact was discharged on nature again, which lasted 60 hours.
- In May 2012, the plan was presented after evaluating the results of the previous attempts for irregular periods from a few hours up to four days to increase the water flow through the dam up to 1275 m³ / s. This drainage patterns will be maintained through 2020.
- The first flooding the new model took place in November 2012 and November 2013.
Carl T. Hayden Visitor Center
At the western end of the dam is the " Carl T. Hayden Visitor Center ." Owned by the Bureau of Reclamation is ( USBR ) operates the Visitor Center by the National Park Service.
In the large round building, which towers above the dam, you have a unique view of the reservoir, the wall, the bridge and the rest of the Colorado River through the huge panoramic windows. An exhibition documented with images, text and video films, the construction of the Glen Canyon Dam and the Glen Canyon Bridge. Other exhibits show pictures of the local area or find out about arts and crafts of the Native Americans. At the reception you can sign up for a tour of the dam. The Visitor Center is open daily except Thanksgiving, December 25 and January 1.