Lake Vogorno

Lake Vogorno
Lake Vogorno as seen from Mergoscia, with Lake Maggiore in the background
Location: Ticino Tributaries: Verzasca Drain: Verzasca Larger places on the shore: Corippo , Vogorno , Mergoscia
Canton Ticino , Switzerland
Coordinates	708 938  /  117 484 coordinates: 46 ° 12 '0 "  N , 8 ° 51' 0"  O ; CH1903:  seven hundred and eight thousand nine hundred and thirty-eight  /  one hundred seventeen thousand four hundred and eighty-four
Data on the structure
Lock type:	Arch dam
Construction time:	1961-1965
Height of the barrier structure :	220 m
Height above the river bed :	204 m
Height of the structure crown:	470  m
Building volume:	660,000 m³
Crown length:	380 m
Crown width:	7 m
Base width:	25 m
Power plant output:	105 MW
Operator:	Verzasca SA officina Idroelettrica
Data on the reservoir
Water surface	1.68 km²
Reservoir length	5.5 km
Total storage space :	105 million m³
Catchment area	233 km²
Design flood :	1 300  m³ / s
Lake Vogorno

The Lago di Vogorno is unused for electricity generation reservoir in the Swiss canton of Ticino . It is located at the exit of the Valle Verzasca (Verzasca Valley) near the municipality of Gordola . Two kilometers downstream, the Verzasca flows into Lake Maggiore . The lake is dammed up by the Contra Dam (also known as the Verzasca Dam), which was completed in 1965 . With its height of 220 meters, it is the fourth highest dam in Switzerland after those of the Lac des Dix , Lac de Mauvoisin and Lago di Luzzone reservoirs .

Building

Dam wall

The dam is an arch dam of concrete m with a height of 220 meters and a length of crown 380 for sale. The barrier is 25 meters thick at the foundation base and 7 meters thick at the crown. It contains 660000 m³ of concrete and has a surface of 44500 m². The dam is slender and has an elliptically shaped horizontal curve. The horizontal curvature decreases from the center towards the foundation base, while the vertical curvature increases from the crown to the base. The thickness is constant except for the part where the dam meets the foundation to reduce pressure on the rock. This carries up to 70 kg / cm². The thickness increases vertically from the crown downwards and describes a slight curve from the center towards the crown. This will reduce the tension if the reservoir is not full. The bottom outlet of the dam consists of two pipes. One leads into a tunnel that diverted the water during the construction of the dam, the other is at the foot of the dam and leads into the river.

Flood reliefs

The dam has two flood reliefs with a capacity of up to 1300 m³ / s. This is especially necessary because the water flow of the Verzasca is subject to very strong seasonal fluctuations and can be up to 1000 m³ / s. Each flood relief has six weirs , each 12 meters wide. From each opening the water flows to a jump, which hurls the water into the middle of the valley 200 meters below. The flood reliefs were later rebuilt in order to improve functionality by enlarging the pillars and adding additional lateral deflectors.

power plant

Up to 50 m³ / s of reservoir water are fed from the reservoir with a storage target of 470 meters above sea level to three vertical 35 MW Francis turbines and one horizontal 4.3 MW Pelton turbine , which are housed in a cavern power station at 193 meters above sea level. From there it is led through a 1.9 km long tunnel into Lake Maggiore . The annual electricity generation is approx. 230  GWh .

Verzasca SA is the builder and owner of the power plant. It has an 80-year license to operate the power plant until 2046. Two thirds of the shareholders are the city of Lugano and one third of the canton of Ticino.

Building history

Verzasca SA was founded on May 6, 1960 to build the Contra Dam as the heart of the Verzasca hydroelectric complex. Construction began in 1961. Planning and construction supervision was carried out by Lombardi & Gellaro Ltd. Because the Contra dam is relatively low compared to other dams in Switzerland, the construction work could be carried out all year round. In order to divert the river and drain the construction site, cofferdams were built and the river diverted through a tunnel that could hold 200 m³ / s. Since the river can carry significantly more water than the tunnel, this was a risk for the engineers.

The concrete work lasted 19 months, with up to 3,100 m³ of concrete being processed per day. The aggregate for the concrete was extracted from a nearby quarry . The gneiss was crushed in a crusher and mixed with the concrete . To make it easier for the concrete to harden, it was cooled using steel pipes that ran through the concrete. It was only waived for the top 30 meters of the dam. A sealing veil was also placed under and around the dam. In August 1964, the reservoir began to be filled. Part of the village of Vogorno was flooded in the summer of 1965; the houses were rebuilt on the slope above the lake. In September 1965 the reservoir was full and construction was completed.

Aerial photograph from July 1964

Civil engineer Giovanni Lombardi describes the lock as one of his finest, mainly because of its slimness and "clean design". As less concrete was used, costs were also reduced.

During the initial filling of the reservoir, seismic activity occurred repeatedly . The earthquakes started in May 1965, and the greatest disturbances occurred between October and November when the reservoir was full. The epicentres were on two faults near the dam. Up to 25 impacts per day were measured. The tremors subsided when the reservoir was emptied and no damage was found to the dam. After refilling, the shocks decreased and it was assumed that an equilibrium was reached that did not react to different water levels. After 1971 no more seismic activity was observed in the area of ​​the dam.

Trivia

Greater awareness gained the dam through the opening scene of the seventeenth James Bond -Streifens Goldeneye (1995): it shows Bond - played by Pierce Brosnan - the dam jumping, which as a double for the fictional chemical weapons factory Arkhangelsk in the Soviet Union during the Cold War served. In fact, the bungee jump was performed by British stuntman Wayne Michaels and was rated by Sky Movies as the best film stunt of all time. Shortly after Goldeneye appeared , the dam's company, Verzasca SA, began lending it to a bungee jump company as a bungee jumping facility. Since then, the dam has been a popular destination for bungee jumpers. According to the company, more than 10,000 visitors have already taken advantage of this offer.

In season 14 of American reality - TV show The Amazing Race dared candidates to bungee jump from the dam.

gallery

• 

  The dam of the Verzasca Dam

• 

  Section through the dam

• 

  Lago di Vogorno from the dam

• 

  Bungee jumping from the dam of Lake Vogorno

• 

  The flood reliefs

• 

  Dam wall

See also

• List of the largest dams on earth
• List of places in Switzerland flooded by reservoirs

Individual evidence

1. ^ Directory of Swiss dams. (No longer available online.) STK Swiss Dam Committee, archived from the original on January 25, 2016 ; accessed on March 16, 2016 . 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.  
2. ^ ^{A b c d e} Henry Gicot Giovanni Lombardo: Some New Arch Dams in Switzerland and Austria . The Japan Dam Association. November 1967. Archived from the original on July 7, 2011. Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. Retrieved October 24, 2010. 
3. ↑ ^{a b} R. Bremen PF Bertola: Increasing the Spillway Capacity at Contra Dam . Lombardi Engineering Inc .. Archived from the original on July 6, 2011. Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. Retrieved October 24, 2010. 
4. ^ Partecipanzione Verzasca ( Italian ) Azienda Elettrica Ticinese. Archived from the original on July 6, 2011. Info: The archive link was automatically inserted and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Retrieved October 24, 2010. 
5. ↑ AIL - Aziende Industriali di Lugano SA - Cenni storici ( Italian ) Archived from the original on September 30, 2007. Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Retrieved May 24, 2007. 
6. ↑ Verzasca SA, 50 years of energy ( Italian ) Corriere de Ticino. May 6, 2010. Archived from the original on May 9, 2010. Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. Retrieved October 24, 2010. 
7. ^ Common Features of the Reservoir-Associated Seismic Activities . Bulletin of the Seismological Society of America. April 1972. Retrieved October 24, 2010.
8. ^ ^{A b c} Roll of Honor , Water Power Magazine. July 9, 1999. Archived from the original on June 14, 2011 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. . Retrieved May 24, 2007.  
9. ↑ ^{a b} Earthquakes Related to Reservoir Filling . National Academies, 1972, p. 14.
10. ↑ NN Ambraseys and SK Sarma: Large Earthquake Forces on Gravity Dam , Nature . September 28, 1968. Retrieved May 24, 2007. 
11. ↑ Seismic Effects at Mangla Dam: Pakistan (PDF; 832 kB) UNESCO . January 1968. Retrieved October 24, 2010.
12. ↑ Jose Oliveria Pedro: Arch Dams: Designing and Monitoring for Safety . International Center for Mechanical Sciences, 1999, ISBN 3-211-3149-5, p. 371.
13. ^ Seismic Activity at Man-made Reservoirs . Proc. Istn Civ. Engineers. September 1971. Retrieved October 24, 2010.
14. ↑ ^{a b c} Matt Munday: For a glad moment I was flying ... then I bombed , The Sunday Times. November 12, 2006. Retrieved November 1, 2010. 
15. ↑ Amazing Race 14 . TV guide. Retrieved February 8, 2009.

Web links

Commons : Lago di Vogorno  - Collection of images, videos and audio files

Commons : Verzasca  - collection of images, videos and audio files

Commons : Contra dam  - collection of images, videos and audio files

• Lago di Vogorno on schweizersee.ch
• Contra dam at the Swiss Dam Committee
• Lake Vogorno. In: Structurae
• Bungee Jumping at the Dam (photographs and video)