Upper Kotmale Dam
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The Upper Kotmale Dam (also known as the Upper Kotmale Hydropower Project, or UKHP) is located in Talawakele, within the Nuwara Eliya District, in the Central Province of Sri Lanka. The dam feeds the third largest hydroelectric power station in the country.


History

The project was initially planned in 1968 by the local authorities, before the
Government of Japan The Government of Japan consists of legislative, executive and judiciary branches and is based on popular sovereignty. The Government runs under the framework established by the Constitution of Japan, adopted in 1947. It is a unitary stat ...
funded a study between 1985 and 1987 to further examine the hydroelectric potential in the upper reaches of Kotmale River. The feasibility study included five sites and eight alternative development schemes, and concluded with two sites which were more technically and economically feasible. The two sites were a conventional type at Caledonia, and a
run-of-the-river Run-of-river hydroelectricity (ROR) or run-of-the-river hydroelectricity is a type of hydroelectric generation plant whereby little or no water storage is provided. Run-of-the-river power plants may have no water storage at all or a limited amou ...
type at Talawakele. The project at Caledonia involved the displacement of over 2,700 families and inundation of large areas of land used for tea plantations, and thus the Caledonia site was dropped. Further funding was then provided by Japan for the engineering study, which included a review of the feasibility study, selection of an optimal development plan, development of the detailed design, and the preparation of tender documents and an environmental impact assessment report. The environmental impact assessment report was completed in September 1994, with the final design report completed in March 1995. The environmental assessment identified key issues associated with the project, which includes impact on St. Clair's Falls aesthetics due to stream flow reductions, social impacts due to resettlement of affected people, possible effects on ground water due to tunnelling, impacts on downstream water uses due to de-watering of streams, and impacts on biodiversity. These impacts led large delays in project development. As per the National Environmental Act of 1998, the environmental clearance was then granted to the project. The project initially faced several objections, before being officially permitted by courts of law. Construction work on the project then began in 2006, and is expected to be completed by the end of 2011.


Construction and development

This project is estimated to cost a total of up to Rs.44 billion, of which Rs.5.931 billion was funded by the
Ceylon Electricity Board The Ceylon Electricity Board - CEB ( si, ලංකා විදුලිබල මණ්ඩලය - ලංවිම, Lankā Vidulibala Mandalaya - Lanwima; ta, இலங்கை மின்சார சபை - இமிச), is the largest el ...
, and ¥33.265 billion by the
Japan Bank for International Cooperation The , JBIC, is a Japanese public financial institution and export credit agency that was created on October 1, 1999, through the merger of the Japan Export-Import Bank (JEXIM) and the Overseas Economic Cooperation Fund (OECF). JBIC became the in ...
. The entire project covers an area of approximately , and is developed in five phases: * Phase 1: Site preparations, construction of employers and workers living quarters, construction of access roads, and relocation of affected people. * Phase 2: All key civil engineering works, such as construction of tunnel, dam, underground power house etc. This takes about 50% of the project cost. * Phase 3: Hydro-mechanical works such as construction of spillways, penstocks, intake gates, etc. * Phase 4: Electro-mechanical works such as generation installations, construction of the switchyard, fire fighting system, communication system, etc. * Phase 5: Construction of the double-circuit
power transmission line Electric power transmission is the bulk movement of electrical energy from a generating site, such as a power plant, to an electrical substation. The interconnected lines that facilitate this movement form a ''transmission network''. This is d ...
. A total of 2,250 construction workers are employed at the site, of which 2,100 are locals, and 150 are foreign.


Dam and reservoir

The gravity dam measures tall, and wide, impounding the Kotmale River and creating the Upper Kotmale Reservoir. Once filled, the reservoir will have a surface area of with an average storage capacity of . The minimum and maximum operating water levels are and AMSL respectively, while the
tailwater Tailwater refers to waters located immediately downstream from a hydraulic structure, such as a dam, spillway, bridge or culvert. Generally measured and reported as the average water depth downstream of a hydraulic structure, tailwater can vary ba ...
level is AMSL. Water from the reservoir will be used for both
irrigation Irrigation (also referred to as watering) is the practice of applying controlled amounts of water to land to help grow crops, landscape plants, and lawns. Irrigation has been a key aspect of agriculture for over 5,000 years and has been devel ...
development and hydroelectric power generation.


Tunnel

The diameter, long Upper Kotmale Tunnel, the longest excavated tunnel in Sri Lanka, will be used to deliver the water to the powerhouse. The tunnel begins at the dam site, and stretches north at a distance of approximately towards Pundaluoya, before stretching a further north-west towards Kumbaloluwa and ending up at its powerhouse at the Kotmale River near Niyamgamdora, at approximately , downstream of the confluence of Pundal River and the Kotmale River. Excavation on the tunnel was completed and ceremonially opened by
President President most commonly refers to: *President (corporate title) * President (education), a leader of a college or university * President (government title) President may also refer to: Automobiles * Nissan President, a 1966–2010 Japanese ...
Mahinda Rajapaksa on 4 November 2010.


Powerhouse

The powerhouse measures long, wide, and tall, and is located underground at Niyamgamdora. It has installed electrical capacity of from two
turbines A turbine ( or ) (from the Greek , ''tyrbē'', or Latin ''turbo'', meaning vortex) is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful Work (physics), work. The work produced by a turbine can be used ...
, capable of producing up to of power annually. Water arrives at the powerhouse from the dam via the long Upper Kotmale Tunnel, which then feeds the
penstock A penstock is a sluice or gate or intake structure that controls water flow, or an enclosed pipe that delivers water to hydro turbines and sewerage systems. The term is inherited from the earlier technology of mill ponds and watermills. H ...
. The initial of the penstock is single-lane, while the latter splits into two lanes, feeding the two generators respectively. The powerhouse consists of the two three-phase , vertical-axis Francis turbine- generators, two three-phase
transformer A transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple circuits. A varying current in any coil of the transformer produces a varying magnetic flux in the transformer' ...
s, and a 220 kV Gas Insulator Switchgear (GIS) substation. An outdoor switchyard measuring by .


Transmission line

The 220kV transmission line of the Upper Kotmale Hydro-power Project connects the power station located at Niyamgamdora, Kotmale, to the national grid via Kotmale switch yard located in Atabage,
Gampola Gampola ( si, ගම්පොල, ta, கம்பளை) is a town located in Kandy District, Central Province, Sri Lanka, governed by an Urban Council. Gampola was made the capital of the island by King Buwanekabahu IV, who ruled for four yea ...
. The line consists of 45 towers and has a length of 15.5 km. The double circuit transmission line has a capacity of 220 MW per circuit.


Social and environmental impact

The construction of the dam, tunnel, and powerhouse, required the relocation of families from 495 houses. New homes were built away from the site with access to vital facilities such as water and power. The relocated families are provided with concessionary loans to start new self-employment ventures, while additional facilities such as the Talawakele Central College, places of worship, a cinema hall, a library, and a community centre, are being established. Similar most other dam's impacts on rivers around the world, the Upper Kotmale Dam will periodically stop the St. Clair's Falls, located downstream of the dam, and a further of the Kotmale River downstream of St. Clairs Falls, before the river is restored by water from the Devon River, the river forming the picturesque Devon Falls. As ordered by the Government Extraordinary, the St. Clair's waterfall will maintain a continuous flow of of water for 10 hours and 30 minutes daily, between sunrise and sunset.


See also

*
Electricity in Sri Lanka The electricity sector in Sri Lanka has a national grid which is primarily powered by hydroelectric power and thermal power, with sources such as photovoltaics and wind power in early stages of deployment. Although potential sites are being id ...
*
Kotmale Dam The Kotmale Dam is a large hydroelectric and irrigation dam in Kotmale, Sri Lanka. The dam generates power from three turbines, totalling the installed capacity to , making it the second largest hydroelectric power station in Sri Lanka. Constru ...
*
List of dams and reservoirs in Sri Lanka The following page lists most dams in Sri Lanka. Most of these dams are governed by the Mahaweli Authority, while the Ceylon Electricity Board operates dams used for hydroelectric power generation. Hydroelectric dams, including small hydros acco ...
*
List of power stations in Sri Lanka Sri Lanka's electricity demand is currently met by nine thermal power stations, fifteen large hydroelectric power stations, and fifteen wind farms, with a smaller share from small hydro facilities and other renewables such as solar. Most hydroe ...


References

{{Inland waters of Sri Lanka 2012 establishments in Sri Lanka Buildings and structures in Nuwara Eliya District Dams completed in 2012 Dams in Sri Lanka Gravity dams Hydroelectric power stations in Sri Lanka