The World’s First Tallest Dam – ‘Nurek Dam’ was built across the Vakhsh River in Tajikistan- a country land locked by mountains in central Asia. The construction of the dam began in 1961, when Tajikistan was a part of a socialist federation of Europe and Asia called ‘Union of Soviet Socialist Republic’ or USSR as it was most commonly known.
The project was completed in 1980; making the Nurek Dam the tallest of all the dams in the world during that period with a height of 300 mtr (980 ft). The dam is mainly a hydroelectric project; though, the water stored in the reservoir is also used for irrigational and other domestic purposes.
Recently in 2013 the completed Jinping-I Arch Dam on Yalong River in Liangshan China, reaching a height of 305 mtr (1001 ft); has surpassed the Nurek Dam making it the second tallest in the world. The Nurek Dam is likely to become the third tallest dam in the world after the completion of ‘Rogun Dam’ in Tajikistan with a maximum height of 335 meters (1099 ft) which is planned to be completed in 2018.
The Nurek Dam is owned and operated by ‘Barqi Tojik’- the national integrated power company of Tajikistan.
Vakhsh River also known as Surkhob is a major river in the landlocked Republic of Tajikistan. It flows from north central Tajikistan to south west and is filled by some of the largest glaciers of Tajikistan. Due to the mountainous terrain of Tajikistan the River passes through many mountains and narrow gorges and the fertile low lands of Tajikistan.
In one of the gorges in western Tajikistan, around 75 km east of its capital Dushanbe is where the Nurek Dam is located. The Dam is build on 300 meters deep Pulsanguin canyon with channel width of around 40 meters. Around 70 kilometers south east of Dushanbe and near to the dam’s site; is the town of ‘Nurek’ which was constructed in 1960 to accommodate engineers and workers employed for the dam’s construction. Nurek town is located in the Khatlon district on the border of Khatlon and Districts of Republican Subordination (13 districts in Tajikistan directly under central rule).
The drive from Dushanbe to Nurek is a pleasant one with many Russian styled country houses called Dacha or vacation homes spanning along the way.
The construction of the Nurek Dam began in 1961 and the dam was commissioned in 1980, when Tajikistan was still a part of Soviet Union. The dam is an earth and rock filled embankment dam which was constructed using locally found materials. The dam was designed by a notable Russian architect, Armen Chaltykjan.
The dam is constructed in the shape of a pyramid with a vertical core in centre to provide additional strength against the forces; the central core consists of clay and stones. The shells on both the upstream and downstream sides of the dam are made up of gravel and pebbles and have a surcharge layer of 20-40 meters and 5-10 meters respectively. The dam consists of 70.6 million cubic yards of earth and concrete.
The height of the dam is 300 mtr (980 ft) and its length is 700 meters (2300 ft). The dam consists of a high level spillway with two radial gates and a low level spillway. The high level spillway consists of two radial gates with a total capacity of 2020 cubic meter/second at Full Supply Level (FSL). The low level intake emergency spillway is located 100 meters below FSL and has a roller gate of specification 8m X 11.5m X 100m.
The Reservoir
The reservoir of the Nurek Dam is also simply known as ‘Nurek’ and is the largest reservoir in Tajikistan with a total capacity of 10.5 cubic kilometers and a surface area of 98 square kilometers. The reservoir spans to over 70 km (40 miles) in length and has a catchment area of 30700 square km. The Dead Storage Level of the reservoir is 6 cubic kilometers. The Full Storage Level and Lowest Level of the reservoir in masl (meters above sea level) are 910 masl and 857 masl respectively.
The water from the reservoir is supplied to the generation plant and also for irrigation through a 14 km long Dangra irrigation tunnel to irrigate nearly 700 square kilometers of farm lands.
The reservoir is also suspected of causing low magnitude earthquakes and other seismic activities.
The Nurek Hydroelectric Power Plant
The Nurek Hydroelectric Power Plant is located at the downstream foot of the dam and supplies almost 98% of the country’s total electricity needs. The power plant by plan is 200m X 50 m and consists of nine vertical axis Francis Turbines of capacity 335 MW each; which, till 1988 had only a capacity of 300 MW each before they were redesigned and reconstructed.
The Power Plant now has a total installed capacity of 3015 MW and a total hydroelectric generating capacity of 4 Giga Watts. The water to the Power House is supplied by a network of tunnels and steel conduits. The power stations first and last generators were commissioned in 1972 and 1979 respectively.
RIS or Reservoir Induced Seismicity
Nurek Dam has long been considered an ideal site to study the Reservoir Induced Seismicity (RIS) i.e. the effect of the huge size of reservoir in causing seismic activities. The geological location of the dam in midst of a narrow and deep canyon make the surroundings more prone to seismic activities given to the huge reservoir capacity and to the length to which it spans.
The Nurek site is one of the jointly monitored sites for RIS; both by the United States of America (USA) and the Soviet Union (USSR).
Q1) What is the name of the World’s First Highest Dam?
Ans- ‘Nurek Dam’ located in the central Asian country of Tajikistan.
Q2) In which country is the dam located?
Ans- In the central Asian country of Tajikistan.
Q3) Across which river was the dam built?
Ans- Across Vakhsh River in Tajikistan.
Q4) When did the construction of the dam began?
Ans- The construction of the dam began in 1961.
Q5) When was the dam completed?
Ans- The dam was completed in 1980.
Q6) Which union was Tajikistan part of while dam’s construction and completion?
Ans- Soviet Union or Union of Soviet Socialist Republics (USSR) from 1929 to 1991.
Q7) What is the height of Nurek Dam?
Ans- The height of the Nurek Dam is 300 meters (980 ft).
Q8) Which dam has surpassed Nurek Dam in terms of height and when?
Ans- The height of Nurek Dam is surpassed by Jinping- I Dam (305 mtr or 1001 ft), China in 2013.
Q9) Which other dam after construction is likely to be the tallest dam in the world?
Ans- Rogun Dam, which is also under construction on Vakhsh River in Tajikistan with a maximum height of 335 mtr (1099 ft).
Q10) Who owns and operates the Nurek Dam?
Ans- The Nurek Dam is owned and operated by ‘Barqi Tojik’- the national integrated power company of Tajikistan.
Q11) How far is the dam’s site from capital Dushanbe?
Ans- Around 75 km east of capital Dushanbe.
Q12) What is the name of town built to accommodate dam’s workers and engineers?
Ans- Nurek Town.
Q13) Name the canyon across which the dam is located?
Ans- Pulsanguin Canyon.
Q14) What is the depth and width of the canyon?
Ans- The canyon is 300 meters deep and 40 meters wide.
Q15) In which district of Tajikistan is the dam located?
Ans- In Khatlon district, on the border of Khatlon and Districts of Republican Subordination (13 districts in Tajikistan directly under central rule).
Q16) What type of dam is Nurek Dam?
Ans- Earth and rock filled embankment dam?
Q17) From where the construction materials procured?
Ans- Construction materials were procured locally.
Q18) Who designed the Dam?
Ans- The dam was designed by a Russian architect Armen Chaltykjan.
Q19) Like which monument is the Dam shaped?
Ans- Like a pyramid.
Q20) What is the central core of the dam made of?
Ans- The central core of the dam is made up of clay and stones.
Q21) What width of shell surcharge layer of upstream and downstream side of the dam?
Ans- 20-40 meters and 5-10 meters respectively.
Q22) What is the height and length of the dam?
Ans- Height of the dam is 300 mtr (980 ft) and its length is 700 mtrs (2300 ft).
Q23) What is the high level spillway intake capacity of the dam?
Ans- 2020 cubic meters /second.
Q24) What is the low level spillway intake capacity of the dam?
Ans- 2020 cubic meter/second.
Q25) How much is the total capacity of the reservoir?
Ans- Total capacity of the reservoir is 10.5 cubic kilometers.
Q26) What is the total catchment area of the reservoir?
Ans- Total catchment area of the reservoir is 30700 square km.
Q27) What is the total surface area of the reservoir?
Ans- Total surface area of the reservoir is 98 square km.
Q28) What is the length of the reservoir?
Ans- The length of the reservoir is over 70 km (40 miles).
Q29) What is the dead storage level of the reservoir?
Ans- The Dead Storage Level of the reservoir is 6 cubic kilometers.
Q30) How much is the maximum and lowest level of the reservoir?
Ans- The maximum and lowest level of the reservoir is 910 masl (meters above sea level) and 857 masl respectively.
Q31) What is the length of Dangra tunnel?
Ans- Nearly 40 kilometers.
Q32) How much farmland does the reservoir irrigates?
Ans- Approximately 700 square kilometers of farm land.
Q33) Where is the power plant located?
Ans- The power plant is located in the downstream foot of the dam.
Q34) How many turbines does the power plant houses?
Ans- Nine Francis Turbines of individual capacity of 335 MW.
Q35) What is the total installed capacity of the plant?
Ans- Total installed capacity of the Power Plant is 3015 MW.
Q36) What was the initially installed capacity of the turbines?
Ans- Initially installed capacity of the turbines was 300 MW.
Q37) When were the turbines reconstructed?
Ans- During the period of 1984 to 1988.
Q38) When was the first generator commissioned?
Ans- First generator of the plant was commissioned in 1972.
Q39) When was the last generator commissioned?
Ans- Last generator of the plant was commissioned in 1979.
Q40) How much percentage of Tajikistan’s total power need is supplied by the Nurek Dam?
Ans- The Nurek Hydropower Station meets almost 98% of the total power demand of Tajikistan generating 4 Giga Watts of hydroelectricity annually.
Q41) What has been the point of study on Nurek Dam?
Ans- RIS or Reservoir Induced Seismicity.