Salal Dam

Salal Dam (Hindi: सलाल बाँध Salāl Bāndh), also known as Salal Hydroelectric Power Station, is a run-of-the-river hydropower project on the Chenab River in the Reasi district of the Jammu and Kashmir.[1] It was the first hydropower project built by India in Jammu and Kashmir under the Indus Water Treaty regime.[2] After having reached a bilateral agreement with Pakistan in 1978,[3] with significant concessions made to Pakistan in the design of the dam, reducing its height, eliminating operating pool, and plugging the under-sluices meant for sediment management, India completed the project in 1987. The concessions made in the interest of bilateralism damaged the long-term sustainability of the dam, which silted up in five years. It currently runs at 57% capacity factor.[note 1] Its long-term future is uncertain.[4][5][6]

Salal Dam
View of Salal Dam from Jyotipuram-Salal road
Location of Salal Dam in Jammu and Kashmir
Official nameSalal Hydroelectric Power Station
CountryIndia
LocationJammu and Kashmir
Coordinates33°08′33″N 74°48′37″E
StatusOperational
Construction began1970
Opening date1987
Construction cost₹ 928.89 crores
Dam and spillways
Type of damGravity dam
ImpoundsChenab River
Height113 m (370.7 ft)
Length487 m (1,597.8 ft)
Dam volume1,450,000 m3 (51,210,000 cu ft)
Spillways12
Spillway typeOgee
Spillway capacity22,427 m³/s
Reservoir
CreatesSalal Lake
Total capacity280,860,000 m3 (228,000 acre⋅ft)
Active capacity12,000,000 m3 (10,000 acre⋅ft)
Surface area3.74 km2 (1.44 sq mi)
Normal elevation487.68 m FRL
Power Station
Operator(s)NHPC
Commission dateStage I: 1987
Stage II: 1995
TypeConventional
Hydraulic head94.5 m (310 ft)
TurbinesStage I: 3 x 115 MW Francis-type
Stage II: 3 x 115 MW Francis-type
Installed capacityStage I: 345 MW
Stage II: 345 MW
Total: 690 MW
Annual generation3082 million kWh
Website
nhpcindia.com

Conception

The project is located on the Chenab River in the Reasi District, a few kilometres south of Matlot, where the river turns to a southerly course. Pakistan's Marala Headworks is 72 km (45 mi) downstream, from where the Marala–Ravi Link Canal and the Upper Chenab Canal carry water to various parts of Pakistani Punjab.[7]

The Salal project was conceived in 1920. Feasibility studies on the project commenced in 1961 by the Government of Jammu and Kashmir and a project design was readied by 1968.[8] Construction was started in 1970 by the Central Hydroelectric Project Control Board (under the Government of India's Ministry of Irrigation and Power). The design of the project contained a two stage powerhouse generating 690 MW power making use of the head created by the dam.[7]

Indus waters dispute

Under the Indus Waters Treaty of 1960, the Chenab River is allocated to Pakistan for exploitation (one of the 'Western Rivers' – Indus, Jhelum and Chenab). India has rights to use the river for "non-consumptive" uses such as power generation. India is obliged under the treaty to inform Pakistan of its intent to build a project six months prior to construction and take into account any concerns raised by the latter.[8]

Since Pakistan lost the three eastern rivers to India by the treaty, its dependence on the Chenab river increased. It viewed the Salal project with great concern. Even limited storage in a relatively low dam upstream was viewed as a flood risk, even a threat, whereby India could flood Pakistan's farm lands by a sudden release of water. Equally, India could hold back water in its reservoir starving them of water. Zulfiqar Ali Bhutto, foreign minister and later prime minister, argued that the dam could be used strategically as an instrument of war to bog down Pakistan's armour. After the two wars of 1965 and 1971, all such theories were easily believable.[8][9][10]

During the negotiations, Pakistan raised technical objections to the design and capacity of the dam. It argued that the 40-foot gates on the spillways gave the dam more storage than allowed by the treaty. It also argued that the under-sluices included for sediment clearing were not permitted under the treaty.[11][note 2] Indians argued that the flood risk that Pakistanis expressed was unreasonable. Any intention on India's part to flood Pakistan would involve causing much more damage to its own territory.[11] In the face of Pakistan's unwillingness to relent, the Indian negotiators wanted to take it to arbitration by a neutral expert, as provided for in the treaty.[14]

However, after signing the 1972 Simla Agreement with Pakistan, India wanted to steer the relations towards bilateralism. Its foreign policy establishment ruled out going to a neutral expert. In further bilateral talks in October 1976, India made significant concessions in the dam's height and other issues. An agreement was reached in 1977, but deferred till after the elections in Pakistan. Soon afterwards, change of government occurred in both India and Pakistan, but the understanding survived.[note 3]

A formal agreement was signed in Delhi on 12 April 1978 by Indian foreign minister Atal Bihari Vajpayee and Pakistan's foreign secretary Agha Shahi.[15][16] The height of spillway gates was reduced from 40 ft to 30 ft. The under-sluices designed for sediment management were permanently plugged.[17][18] The agreement was hailed as a triumph of bilateralism, facilitating an atmosphere of trust and confidence between the two countries.[11][19] But the agreement also seriously damaged the sustainability of the dam and the Indian engineers viewed it as too high a price to pay for bilateralism.[20]

Final construction
Spillway at the top of the Concrete Dam

After signing the agreement in 1978, the construction of the project was entrusted to National Hydroelectric Power Corporation (NHPC) on an agency basis.[21] NHPC was incorporated by the Government of India in 1975, with an authorised capital of Rs. 200 crore. The Salal project was its first project.[22]

The Stage-I of the powerhouse was commissioned in 1987; Stage-II between 1993–1995. The final commissioning of the project took place in 1996.[21]

Salal power Station

After completion, the Salal project was transferred to NHPC on an ownership basis.[22] The Government of Jammu and Kashmir is said to have had a Memorandum of Understanding with the Government of India to receive the project at a depreciated cost.[23] However, according to the National Conference party, the coalition government in power at 1985, run by the Ghulam Mohammad Shah-wing of the National Conference and the Indian National Congress, surrendered the state's rights over the project.[24]

The state of Jammu and Kashmir receives 12.5 percent of the energy generated from the project.[25] The rest is transmitted to the Northern Grid where it is distributed to the states of Punjab, Haryana, Delhi, Himachal Pradesh, Rajasthan, and Uttar Pradesh. Jammu and Kashmir also purchases additional power at regular prices.[24][26]

Siltation

Sediment is a serious problem among Himalayan rivers (since the Himalayas are young mountains).[27] The Chenab river, especially, carries more silt than the others even among the 'Western Rivers'. Its annual silt load is estimated to be 32,000,000 m3 (26,000 acre⋅ft).[28]

The silted reservoir, with the crest of the dam to the right

From the very first year of operation, the reservoir of the Salal dam started silting up. Two severe floods in 1988 and 1992 further accelerated the siltation.[29] Within five years, the reservoir got silted up almost entirely.[30] As a result, the reservoir capacity got reduced from the intended 231,000 acre⋅ft (285,000,000 m3) to 7,000 acre⋅ft (9,000,000 m3).[29]

As per the 1978 Salal agreement, the reservoir had to be maintained at Constant Full Reservoir Level at 487.68 m asl. Six under-sluices that were provided during the construction had to be plugged at the beginning of operation. Consequently, the 9.14 m (30 ft) high spillway gates form the only live storage of the reservoir. The rest is dead storage, which ended up acting as a siltation tank.[31] To alleviate the problem, the spillway gates are being opened at least once a month during the monsoon season as a desilting mechanism, with a discharge of about 4,250 cumecs. This is reported to have recovered some of the reservoir capacity, increasing it to 10,000 acre⋅ft (12,000,000 m3).[32]

As the spillway and the power intake are continuously passing sand, they cause abrasion damage to the spillway concrete structure and the turbine equipment.[33] Studies report erosion in the civil structures such as the concrete sill of the spillway, the glacis and the bucket;[34] damage to the turbine components such as cracks in the turbine blades, knife edging of the outer edges and washing out of other components;[35] damage to the cooling system such as tubes being choked with stator faults encountered.[35] NHPC has been using various technical remedies to address these problems.[36]

The silt accumulation has essentially converted the reservoir into an elevated river bed.[28] The situation is reported to be alarming and the future of the project uncertain.[5] "During winters when water level goes abysmally down, it does not generate much [power]," according to a state official.[4] In 2014–2015, the two powerhouses reported producing 3491 million KWH,[37] representing 57% capacity factor.[note 1]

Technical parameters
Penstocks, used to move gushing water from dam to turbine

The original Indian design provided for a 130 metre-high dam up to an elevation of 1627 ft above sea level, a 40 ft gated spillway at the top (between elevations 1560–1600 ft) and six under-sluices at elevation 1365 ft.[3] The under-sluices would have enabled the 'drawdown flushing' of sediments.[note 4] However, at Pakistan's insistence, the under-sluices were permanently plugged with concrete, and the gates were reduced from 40 ft to 30 ft. This meant that the only live storage is between elevations 1570–1600 ft, and the storage below that level has gotten silted up, forming an elevated river bed. The level of the bed now varies between 477 m (1,565 ft) and 484 m (1,588 ft).[39]

Dam
  • Top elevation : 495.91 m (1,627 ft) asl
  • Maximum water level : 494.08 m (1,621 ft) asl
  • Full Reservoir level : 487.68 m (1,600 ft) asl[40]
  • Dead storage level : 478.68 m (1,570 ft) asl[40]
  • Operating pool : Nil[3]
  • Length of power dam : 105 m
  • Length of non overflow dam : 125 m
  • Type of gate : Radial
  • Deepest foundation level : 383 m
  • No of river sluices : 6 of 3.35 m x 4.57 m

Tailrace tunnel
  • Number : Two
  • Length Stage I : 2.463 km
  • Stage II : 2.523 km
  • Shape : Horseshoe
  • Diameter : 11 m (finished)
  • Design discharge : 412 m³/s
  • Velocity : 4.2 m/s[26]

Transmission lines
  • Name of Grid : Northern grid
  • Transmission Voltage : 220 kV
  • Total length of lines : 446 km
  • Double circuit Salal - Kishenpur : 2 lines
  • Single circuit Salal - Jammu : 2 lines
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See also

Notes
  1. At full capacity, a power station generates 8.76 million units (kWh) per megawatt of installed capacity. In early 1990s, Chenab projects produced 6.93 million units per installed MW. In 2012–13, Salal produced only 4.74 million units, [38] with a small improvement to 5.06 million units in 2014–15.
  2. The Indus Waters Treaty actually states (Annexure D, Paragraph 8): "There shall be no outlets below the Dead Storage Level, unless necessary for sediment control or any other technical purpose; any such outlet shall be of the minimum size, and located at the highest level, consistent with the sound and economical design and with satisfactory operation of the works."[12][13]
  3. In Pakistan, General Zia-ul-Haq came to power overthrowing Zulfikar Ali Bhutto's government. In India, the Janata Party won the elections in 1977.
  4. Drawdown flushing is a technique of sediment management, whereby the reservoir is drawn down to some level above that of under-sluices ("minimum drawdown level") before a flooding season. The gates of the spillway are kept open as the flood arrives, allowing it to wash away settled sediment.[13]

References
  1. "NHPC investment crosses Rs 18,800 crore in J&K". The Tribune. 7 May 2016.
  2. Muhammad Jehanzeb Masud Cheema and Prakashkiran Pawar, Bridging the Divide, Stimson Centre, 2015, Table 2 (p. 14).
  3. "Agreement between the Government of India and the Government of the Islamic Republic of Pakistan regarding the Salal Hydroelectric Plant" (PDF). commonlii.org. Commonwealth Legal Information Institute. 14 April 1978. Retrieved 13 June 2018.
  4. Kishanganga could have larger impact than expected, The Economic Times, 21 February 2013.
  5. Siltation renders Salal hydro-power project's future uncertain, Outlook, 31 July 2002.
  6. Ramaswamy R. Iyer, Arbitration & Kishenganga project, The Hindu 25 June 2010.
  7. Dar, Power Projects in Jammu & Kashmir (2012), p. 7.
  8. Raghavan, The People Next Door (2019), pp. 142–143.
  9. Zawahri, India, Pakistan and cooperation (2009), p. 11.
  10. B. G. Verghese, Ideology Threatens Indus Treaty, The South Asian Journal, 25 March 2010.
  11. Akhtar, Emerging Challenges to Indus Waters Treaty (2010).
  12. Raymond Lafitte, Baglihar Hydroelectric Project: Expert Determination (12 February 2007), Ministry of Water Resources, Government of Pakistan.
  13. Guidelines for Sediment Management in Water Resources & Hydropower Projects, Central Water Commission, Government of India, February 2019.
  14. Raghavan, The People Next Door (2019), pp. 143–144.
  15. Raghavan, The People Next Door (2019), p. 144.
  16. Jayapalan, N (2000), India and Her Neighbours, Atlantic Publishers & Dist, p. 79, ISBN 978-81-7156-912-0
  17. Bakshi & Trivedi, The Indus Equation (2011), p. 78.
  18. Extracts from Rajya Sabha debates, 3 August 1978.
  19. Tabassum, The Role of CBMs (2001), pp. 396–397.
  20. Raghavan, The People Next Door (2019), pp. 144–145.
  21. Dar, Power Projects in Jammu & Kashmir (2012), pp. 7–8.
  22. Dar, Power Projects in Jammu & Kashmir (2012), pp. 19–20.
  23. Dar, Power Projects in Jammu & Kashmir (2012), pp. 23–24.
  24. Salal power project has NC-PDP tripping down each other, Hindustan Times, 7 June 2011.
  25. Dar, Power Projects in Jammu & Kashmir (2012), p. 24.
  26. "Projects: Salal". nhpcindia.com. NHPC Limited. 2016.
  27. Akhter 2013, p. 25.
  28. Visvanathan, Silt Disposal from Reservoirs (2000), p. I-7.
  29. Visvanathan, Silt Disposal from Reservoirs (2000), p. I-7; Darde, Detrimental effects of tiny silt particles (2016), pp. 144–145
  30. Alam, Sedimentation management in hydro reservoirs (2013): "The reservoir is full of sediment, to the water surface level at the upstream end and to the spillway crest level at the downstream end."
  31. Darde, Detrimental effects of tiny silt particles (2016), p. 144; Visvanathan, Silt Disposal from Reservoirs (2000), p. I-7
  32. Visvanathan, Silt Disposal from Reservoirs (2000), p. I-7; Darde, Detrimental effects of tiny silt particles (2016), p. 144
  33. Alam, Sedimentation management in hydro reservoirs (2013).
  34. Darde, Detrimental effects of tiny silt particles (2016), pp. 144–145.
  35. Darde, Detrimental effects of tiny silt particles (2016), p. 145.
  36. Dhar, D. P. (2002), "Silting Problems in Hydro Plants and their Remedial Measures", in S.P. Kaushish; B.S.K. Naidu (eds.), Silting Problems in Hydropower Plants, CRC Press, pp. 176–184, ISBN 978-90-5809-238-0
  37. Review of Performance of Hydro Power Stations, 2014-15, Central Electricity Authority, p. 44.
  38. Hydropower Generation Performance in Chenab River Basin, South Asia Network on Dams, Rivers and People (SANDRP), 21 June 2013.
  39. Darde, Detrimental effects of tiny silt particles (2016, pp. 144–145)
  40. Visvanathan, Silt Disposal from Reservoirs (2000), pp. I-7–I-8; Darde, Detrimental effects of tiny silt particles (2016), p. 144

Bibliography


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