Nikachhu Dam Site

The Nikachhu Dam is the primary structure of the Nikachhu Hydropower Project, a 118 MW run-of-river scheme on the Nikachhu River in Trongsa District, central Bhutan. The dam sits between the confluences of the Nikachhu with the Chhunabchhu and the Nikachhu with the Mangdechhu, roughly three kilometres downstream of the Chhunabchhu junction. Built by Tangsibji Hydro Energy Limited (THyE), a wholly owned subsidiary of Druk Green Power Corporation, the project was Bhutan's first hydropower scheme financed partly through the Asian Development Bank and Indian commercial banks rather than purely through bilateral India–Bhutan agreements.

Technical Specifications

The dam is a 38-metre-high concrete gravity structure impounding a reservoir of approximately 0.537 million cubic metres. Water is diverted through a 12,144-metre (12.1 km) head race tunnel with a diameter of four metres, feeding into an underground powerhouse equipped with two Pelton turbines. The design annual generation capacity is 491 million kilowatt-hours (units). After passing through the turbines, the tailwater discharges into the reservoir of the Mangdechhu Hydroelectric Project downstream, integrating the two schemes hydraulically.

Key figures: installed capacity 118 MW (2 × 59 MW Pelton turbines); dam height 38 m; head race tunnel 12,144 m; design generation 491 GWh per year; total project cost approximately BTN 12 billion (approximately US

Installed capacity: 118 MW (2 × 59 MW Pelton turbines)

Dam height: 38 m (concrete gravity)

Head race tunnel: 12,144 m

Design generation: 491 GWh/year

Total project cost: ~BTN 12 billion (~US$143.9 million)

43.9 million).

Financing and Development

THyE was incorporated on 25 April 2014 as a special purpose vehicle to implement the project. Financing came from a mix of sources: the Asian Development Bank committed approximately US$120.5 million, while the State Bank of India provided INR 2.5 billion and India's Exim Bank contributed INR 1.03 billion. The total project cost was estimated at approximately BTN 12 billion (about US$143.9 million). This financing model — blending multilateral development bank loans with Indian commercial lending — was a departure from the conventional bilateral grant-and-loan arrangements that funded earlier Bhutanese hydropower projects such as Chhukha and Tala.

Construction and Commissioning

Civil works began in mid-2016. The project encountered delays due to geological conditions — the rock quality at the head race tunnel site proved worse than the geological baseline predicted, substantially slowing tunnelling progress. The COVID-19 pandemic created further setbacks, as both civil and hydro-mechanical contractors had difficulty mobilising skilled and unskilled workers from their home countries to the site. Originally expected to finish by 2020, the project was eventually commissioned in 2023.^[1] In December 2025, the 70th Je Khenpo, Trulku Jigme Choedra, conducted blessing ceremonies at the completed plant alongside other major hydropower facilities.

Significance

The Nikachhu project added 118 MW to Bhutan's installed hydropower capacity, supplementing the 720 MW Mangdechhu plant in the same river system. Its ADB-backed financing model served as a test case for diversifying Bhutan's hydropower financing beyond bilateral Indian arrangements — a model subsequently discussed for other planned projects.

References

1. Nikachhu plant set to commission by December — Kuensel Online
2. Bhutan: Second Green Power Development Project — Asian Development Bank
3. Power Plant Profile: Nikachhu, Bhutan — Power Technology
4. Nikachhu Hydropower Project Instrumentation — Encardio Rite
5. Tangsibji Hydro Energy Limited — Official Website