Nagarjuna Sagar Dam

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Nagarjuna Sagar Dam
Nagarjuna Sagar Dam
నాగార్జునసాగర్ ఆనకట్ట
नागार्जुन सागर बांध
Nagarjuna Sagar Dam is located in India
Nagarjuna Sagar Dam
Location of Nagarjuna Sagar Dam
Official name నాగార్జునసాగర్ ఆనకట్ట
Nagarjuna Sagar Dam
नागार्जुन सागर बांध
Location Nalgonda district, Telangana and Guntur district, Andhra Pradesh
Coordinates 16°34′32″N 79°18′42″E / 16.57556°N 79.31167°E / 16.57556; 79.31167Coordinates: 16°34′32″N 79°18′42″E / 16.57556°N 79.31167°E / 16.57556; 79.31167
Construction began 10 December 1955
Opening date 1967
Construction cost 1300 crore rupees
Dam and spillways
Impounds Krishna River
Height 124 metres (407 ft) from river level
Length 1,550 metres (5,085 ft)
Creates Nagarjuna Sagar Reservoir
Total capacity 11,560,000,000 m3 (9,371,845 acre·ft)
Active capacity 5,440,000,000 m3 (4,410,280 acre·ft)[1]
Catchment area 215,000 square kilometres (83,000 sq mi)
Surface area 285 km2 (110 sq mi)
Power station
Commission date 1978-1985
Turbines 1 x 110 MW (150,000 hp) Francis turbines, 7 x 100.8 MW (135,200 hp) reversible Francis turbines
Installed capacity 816 MW (1,094,000 hp)

Nagarjuna Sagar Dam was built across the Krishna River at Nagarjuna Sagar where the river is forming boundary between Nalgonda district of Telangana state and Guntur district of Andhra Pradesh state in India. The construction duration of the dam was between the years of 1955 and 1967. The dam created a water reservoir whose gross storage capacity is 11,472,000,000 cubic metres (4.051×1011 cu ft). The dam is 490 feet (150 m) tall from its deepest foundation and 0.99 miles (1.6 km) long with 26 flood gates which are 42 feet (13 m) wide and 45 feet (14 m) tall.[2] Nagarjuna Sagar was the earliest in the series of large infrastructure projects initiated for the Green Revolution in India. It is also one of the earliest multi-purpose irrigation and hydro-electric projects in India. The dam provides irrigation water to the Prakasam, Guntur, Krishna, Khammam, West Godavari and Nalgonda districts along with hydro electricity generation.

Foundation stone of Nagarjuna Sagar


The proposal to construct a dam to use the excess waters of the Krishna river was planned by the Nizam of Hyderabad and engaged British Engineers in 1903 to irrigate Telangana. Since then, various competing sites in Siddeswaram, Hyderabad and Pulichintala were identified as the most suitable locations for the reservoirs. The perseverance of the Raja Vasireddy Ramagopala Krishna Maheswar Prasad (Raja of Muktyala) who donated 55000 acres of his land and fifty five million British Pounds in wealth paved way for the site identification, design and construction of the dam.[3][4][5] Nagarjunasagar was the earliest in the series of "modern temples" taken up to usher in the Green Revolution in India.[4] The dam was built with local know how under the able engineering leadership of K.L. Rao.

Project construction was officially inaugurated by Prime Minister Jawaharlal Nehru on 10 December 1955 and proceeded for the next twelve years. The reservoir water was released into the left and right bank canals by Prime Minister Indira Gandhi in 1967.[6] Construction of the hydropower plant followed, with generation increasing between 1978 and 1985, as additional units came into service.

The construction of the dam submerged an ancient Buddhist settlement, Nagarjunakonda, which was the capital of the Ikshvaku dynasty in the 1st and 2nd centuries, the successors of the Satavahanas in the Eastern Deccan. Excavations here had yielded 30 Buddhist monasteries, as well as art works and inscriptions of great historical importance. In advance of the reservoir's flooding, monuments were dug up and relocated. Some were moved to Nagarjuna's Hill, now an island in the middle of the reservoir. Others were moved to the mainland.[7]


Nagarjuna Sagar right Earth Dam
  • Catchment Area : 215,000 km2 (83,000 sq mi)
  • Location of dam : Nalgonda District and Guntur District
  • Reservoir
    • -+Water spread area at FRL of dam : 285 km2
  • Masonry dam
    • Spillway of dam : 471 m
    • Non-over flow dam : 979 m
    • Length of Masonry dam : 1450 m
    • Maximum height : 125 m
  • Capacity in TMC's : 157.61
  • Earth dam
    • Total Length of Earth dam : 3414 m
    • Maximum height : 128 m
  • Power Generation
    • Power Units : 1 No. conventional (110 MW capacity), 7 nos Reversible (100 MW capacity)
  • Canal power house
    • Right side : 3 units 30 MW (each)
    • Left side : 2 units 30 MW (each)[8]

Effect of the project[edit]

The right canal (Jawahar canal) is 203 km (126 mi) long with 400 cumecs capacity and irrigates 1.113 million acres (4,500 km2) of land in Guntur and Prakasam districts. The left canal (Lalbahadur Shastri canal) is 295 km (183 mi) long with 400 cumecs capacity and irrigates 0.32 million acres (1,300 km2) of land in Nalgonda, Krishna, West Godavari and Khammam districts. The project transformed the economy of above districts. 52 villages were submersed in water and 24000 people were affected. The relocation of the people was completed by 2007.[5]

Power generation[edit]

The hydroelectric plant has a power generation capacity of 815.6 MW with 8 units (1x110 MW+7x100.8 MW). First unit was commissioned on 7 March 1978 and 8th unit on 24 December 1985. The right canal plant has a power generation capacity of 90 megawatts (120,000 hp) with 3 units of 30 megawatts (40,000 hp) each. The left canal plant has a power generation capacity of 60 megawatts (80,000 hp) with 2 units of 30 MW each.[9] The tail pond is under advanced stage of construction to put to use the pumped storage features of 7x100.8 MW units.

Many times, it happens that power generation from the 150 MW canal based units is not optimised when the Nagarjunasagar reservoir is overflowing on its spillway and very less water is required for irrigation from the canals during the monsoon floods. Power generation from canal based hydro units can be optimised by running these units during the flooding period by releasing the water fully in to the canals. The unwanted canal water can be released in to the natural stream when it is crossing the major stream. Thus run off power can be generated from the water going down unutilised in to the river by the canal based power units also.

The water level in the Nagarjunasagar reservoir shall be maintained above the minimum level required for these units in most of the time by releasing water from the upstream Srisailam reservoir to optimise the power generation from the canal based units during dry season.

Tapping dead storage potential[edit]

The left and right bank canals sill level is fixed at 490 feet (150 m) MSL to supply irrigation water to two million acres. The unutilized storage capacity is nearly 180 TMC below the canals sill/bed level.[10] Nagarjuna Sagar reservoir also meets the Krishna delta water requirements to the extent of 80 TMC by letting water down stream into the river. Nearly 1.3 million acres (5,300 km2) is irrigated under Krishna Delta Canals. There is a possibility to utilize most of this idle dead storage capacity to store the river flood water further and to use as carry over storage. Nearly 150 TMC idle storage up to 380 ft MSL, can be used leaving 30 TMC for silt settlement. This is possible by installing Water Powered Pump[11] (WPP) units at the base of the dam.

WPP units are to be located at the toe of the Nagarjuna Sagar dam with tail water level of 240 ft MSL on either side of the river. The WPP units can be connected below 380 ft MSL level to the reservoir with the technique called under water reservoir / lake tapping.[12] Under water lake tapping method was implemented successfully in Koyna Hydroelectric Project to install additional hydroelectric units without emptying the Koyna reservoir. The cost would be Rs 15 billion for utilizing 150 TMC storage additionally. If the same storage is created under a new reservoir, it would cost not less than Rs 50 billion. Water can be supplied to high level canals at sill 580 ft MSL on both right and left banks without consuming electricity with WPP units to irrigate dry lands further in Nalgonda, Warangal, Khammam, and Guntur districts

Alternatively, floating/barge mounted pumps can be installed along with associated piping on the reservoir bed to pump water from the reservoir dead storage in to left and right bank canals and the approach channel of the existing pump house of Hyderabad water supply scheme during drought years. During the good monsoon years, when the reservoir water level is above the dead storage level, the same barge mounted pumps can be used regularly to pump water in to the existing high level (flood flow) canal (near 16°39′27″N 79°15′43″E / 16.65750°N 79.26194°E / 16.65750; 79.26194) located on the left bank of the reservoir in Nalgonda district. Similarly, during the good monsoon years, a lift irrigation scheme can be taken up with the help of the same barge mounted pumps to lift water from the reservoir (near 16°21′41″N 79°14′31″E / 16.36139°N 79.24194°E / 16.36139; 79.24194) by 45 m high for irrigating nearly 200,000 acres of uplands situated adjacent to the reservoir in Guntur district. Thus all the installed barge mounted mobile pump houses can be used for regular pumping needs to maximise the water use from the reservoir in every year.

Godavari water transfer via Nagarjuna Sagar left canal[edit]

Nagarjuna Left Canal deep cut before entering the gravity tunnel

The Nagarjuna Sagar left canal is presently supplying nearly 130 TMC water for irrigation needs in Telangana and Andhra Pradesh states. This is a contour gravity canal with gradual downward gradient (≃ 1:10,000) along the water flow direction. This canal can be used for transferring nearly 80 TMC Godavari river water in to the Nagarjuna Sagar reservoir in addition to supplying the Godavari water under its entire command area. Thus total 210 TMC Godavari water can be used in the Krishna basin of Telangana state from Srisailam and Jurala reservoirs for the new projects with 100% water dependability. Godavari water transferred in to Nagarjuna Sagar reservoir/Krishna main river can also be used for the proposed Palamuru lift irrigation and Nakkalagandi lift irrigation schemes in Telangana.

This is possible by re-engineering of the left canal to reverse its water flow direction from the location (near 17°22′13″N 80°21′43″E / 17.37028°N 80.36194°E / 17.37028; 80.36194) where Godavari water would be pumped in to this canal. The canal embankments would be raised to facilitate flow reversing towards Nagarjuna Sagar reservoir and intermediate pumping stations (with low head & high flow concrete volute pumps) would be installed near the Paleru balancing reservoir, Pedda Devulapalli balancing reservoir, present tunnel inlet near the Nagarjuna Sagar reservoir and the existing major aqueducts across Halia, Musi and Munneru tributaries. The cost of this canal redesigning and the associated pump houses would be one third of a new scheme to transfer Godavari river water in to Nagarjuna Sagar reservoir at its FRL 590 feet MSL with least possible total pumping head.[13] The above re-engineering of the canal is similar to modifications carried out to reverse the water flow of ancient Grand canal under Eastern Route project of South to North Water Transfer in China.[14]

See also[edit]


External links[edit]

Media related to Nagarjuna Sagar Dam at Wikimedia Commons