Uma Oya Hydropower Complex

The Uma Oya Hydropower Complex (also internally called Uma Oya Multipurpose Development Project or UOMDP) is a irrigation and hydroelectric complex currently under construction in the Badulla District of Sri Lanka. Early assessments of project dates back to 1989, when the first studies was conducted by the country's Central Engineering and Consultancy Bureau. The complex involves building a dam across Dalgolla Oya, and channelling water over a 3,975 m (13,041 ft) tunnel to Mathatilla Oya, both of which are tributaries of the Uma Oya. At Mathatilla Oya, another dam is constructed to channel 145,000,000 m3 (5.1×109 cu ft) of water per annum, via a 15,290 m (50,160 ft) headrace tunnel to the Uma Oya Power Station, where water then discharged to the Alikota Aru via a 3,335 m (10,942 ft) tailrace tunnel. The Alikota Aru is a tributary of the Kirindi Oya.[1][2]

Uma Oya Hydropower Complex
Location of Uma Oya Hydropower Complex in Sri Lanka
Official nameUma Oya Multipurpose Development Project
CountrySri Lanka
LocationUva Province
CoordinatesPD: 06°54′51″N 80°56′00″E
DD: 06°53′13″N 80°57′23″E
PurposeIrrigation and Power
Construction beganApril 2008
Dam and spillways
Type of damGravity dams
ImpoundsPD: Dalgolla Oya
DD: Mathatilla Oya
Height (foundation)PD: 45 m (148 ft)
DD: 50 m (160 ft)
LengthPD: 175 m (574 ft)
DD: 165 m (541 ft)
Dam volumePD: 50,000 m3 (1,800,000 cu ft)
DD: 70,000 m3 (2,500,000 cu ft)
SpillwaysPD: 3
DD: 3
Spillway typeChute spillways
Spillway capacityPD: 2,828 m3/s (99,900 cu ft/s)
DD: 2,161 m3/s (76,300 cu ft/s)
Reservoir
CreatesPuhulpola Reservoir/Dyraaba Reservoir
Total capacityPR: 634,826 m3 (22,418,700 cu ft)
DR: 970,135 m3 (34,260,000 cu ft)
Uma Oya Power Station
Operator(s)Ceylon Electricity Board
TypeConventional
Turbines2 × 60 MW
Installed capacity120 MW
Annual generation231 GWh

The construction of the complex was inaugurated in April 2008 by former President Mahinda Rajapaksa and President Mahmoud Ahmadinejad.[3] The total project cost is estimated to be approximately US$529 million (approximately Rs. 80 billion), 85% of which is provided by the Government of Iran.[4]

History

In 2008 Sri Lankan government began the project with Iranian funding and the foundation stone for the project without obtaining Environmental Clearance for the project. Environmental Impact Assessment (EIA) Report of the Uma Oya Project was prepared by the University of Sri Jayawardhanapura and was submitted in November 2010. During the 30 working days the EIA was open to the public for review and comments Central Environmental Authority received many letters from environmental organizations who called the EIA inadequate. However despite the objections CEP gave clearance for the project.[5][6]

Puhulpola Dam
Puhulpola Dam under construction in March 2018.

Dalgolla Oya is impounded by the roller-compacted concrete Puhulpola Dam (PD), which is a gravity dam measuring 175 m (574 ft) and 45 m (148 ft) in length and height, respectively. The damming of this river creates the Puhulpola Reservoir (PR), which has a gross storage of 634,826 m3 (22,418,700 cu ft). The dam has a volume of approximately 50,000 m3 (1,800,000 cu ft), and consists of three chute spillways, allowing a combined discharge of up to 2,828 m3/s (99,900 cu ft/s).

Water from the Puhulpola Reservoir is channelled to the Dyraaba Dam's reservoir via a 3,975 m (13,041 ft) horse-shoe shaped free-flow conveyance tunnel, measuring 4.10 m (13.5 ft) and 3.95 m (13.0 ft) in width and height respectively, and with a discharge capacity of 15 m3/h (530 cu ft/h). Construction of the tunnel was completed on 14 January 2017.[7] To build the tunnel, a drill-and-blast excavation method was used to displace approximately 55,000 m3 (1,900,000 cu ft) of earth.[8]

Dyraaba Dam
Dyraaba Dam under construction in March 2018.

With a concrete volume of more than 70,000 m3 (2,500,000 cu ft), the Dyraaba Dam (DD) measures 165 m (541 ft), 50 m (160 ft), and 6 m (20 ft), in length, height, and crest width, respectively. It is constructed 986 m (3,235 ft) above mean sea level (MSL), and can withstand an estimated flood level of 995 m (3,264 ft) MSL. Just like the Puhulpola Dam, the Dyraaba Dam consists of three chute spillways, allowing a combined discharge of up to 2,161 m3/s (76,300 cu ft/s).

The dam creates the Dyraaba Reservoir (DR) which has a gross storage of 970,135 m3 (34,260,000 cu ft) and active storage of 600,000 m3 (21,000,000 cu ft). Water from the reservoir is channelled through a 15,290 m (50,160 ft) long circular pressurised-flow headrace tunnel measuring 4.25 m (13.94 ft) in diameter, which has a discharge capacity of 19.5 m3/h (690 cu ft/h). To build the tunnel, a 180 m (590 ft) long TBM was used to displace approximately 222,000 m3 (7,800,000 cu ft) of earth.

Uma Oya Power Station

The two pelton turbine generators of 60 megawatt are fed via a 600 m (2,000 ft) vertical pressure shaft, after passing through the long tailrace tunnel. 68,000 m3 (2,400,000 cu ft) of earth was cleared to create the underground Uma Oya Power Station cavern. The 120 megawatt power station will generate up to 231 GWh per year.[9]

The 5,000 m2 (54,000 sq ft) switchyard premises is built at 504 m (1,654 ft) above MSL. Power from the switchyard is delivered over 21.5 km (13.4 mi) of double-circuit 132KV transmission line, consisting of more than 70 transmission towers, to the Badulla Substation.

The annual discharge of approximately 145,000,000 m3 (5.1×109 cu ft) of water from the power station is distributed out via a 3,335 m (10,942 ft) cross-basin tailrace tunnel for agriculture use on 15 km2 (5.8 sq mi) or existing land and 45 km2 (17 sq mi) of new lands, including irrigation of 14 separate tanks.[1]

Impact

The project is considered as one of the worst environmental disasters in Sri Lanka.[10][11] It has been called the "Multi-destructive" project due its large negative effects. As a result of the project houses began collapsing, land surfaces cracking, wells and brooks drying up, residents being displaced and losing their traditional livelihood. Many mass protests were launched against the project by residents affected by the Uma Oya disaster.[12]

It was revealed that impact of this Uma Oya project mainly because of bad Environmental Impact Assessment (EIA) report. [13] The Rajapaksa regime has also been accused of corruption in the project. Critics have accused that Rajapaksa used the project as an cover up to misuse funds. The costs of the project was increased by USD 248 million which resulted in the Irrigation ministry secretary who refused to sign the agreement resigning and his successor started the project despite heavy opposition.[14][15]

Uma Oya Project temporary stop under Ranil Wikramasinghle Government. Due to the delay of contraction of Uma Oya Power Station, Government had to impose four hours per day power cuts & sign agreement to purchase electricity from private sector at huge cost.

See also

References
  1. Sriyananda, Shanika (27 March 2015). "Uma Oya Project: More damages than benefits?". Daily FT. Retrieved 1 July 2017.
  2. Jayawardena, Dulip (8 April 2015). "Uma Oya Trans–Basin Multipurpose Project – A critical review". Daily Mirror. Retrieved 1 July 2017.
  3. Upadhayay, Shradha. "Uma Oya Multi-purpose Project". International Rivers. Retrieved 1 July 2017.
  4. "Uma Oya Hydropower". Ministry of Power and Renewable Energy. Retrieved 1 July 2017.
  5. Nathaniel, Camelia (15 March 2015). "Uma Oya Project: More Damage Than Benefit!". The Sunday Leader. Retrieved 2 July 2017.
  6. Ismail, Amra (3 January 2017). "Uma Oya Development Project: Multi-purpose or multi-destructive?". Daily Mirror. Retrieved 2 July 2017.
  7. "Major milestone achieved in Uma Oya project". The Island. 29 January 2017. Retrieved 1 July 2017.
  8. Indunil, Isuru. "Uma Oya Multi-Purpose Development Project". The Institute of Engineers, Sri Lanka. Retrieved 1 July 2017.
  9. "Uma Oya Underground Power Plant". Shahran Sazeh. Retrieved 1 July 2017.
  10. Nizam, Ifham (19 September 2016). "Uma Oya Project To Benefit or Ruin?". The Sunday Leader. Retrieved 2 July 2017.
  11. "Uma Oya Multipurpose Development Project & Its Impacts". Department of Forestry and Environmental Science: University of Sri Jayewardnapura. 7 April 2015. Retrieved 2 July 2017.
  12. Dias, Keshala (28 June 2017). "Mass protest in Bandarawela against Uma Oya water project". News First. Retrieved 2 July 2017.
  13. "Uma Oya tragedy is all because of a bad EIA, activists charge". sundaytimes. 16 July 2017. Retrieved 22 October 2017.
  14. "This is how Uma Oya swallowed $248 million". Sri Lanka Mirror. 30 June 2017. Retrieved 2 July 2017.
  15. "Uma Oya project estimate bloated: CaFFE Executive Director". Daily News. 1 July 2017. Retrieved 2 July 2017.
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