New Delhi: In what can be termed as significant headway for cooperation in the hydropower sector between India and Bhutan, the governments of the two South Asian neighbours have finally agreed to recommence construction of the 1,200 MW Punatsangchhu-I Hydroelectric Project (PHEP-I) after work was halted at the initial stage itself due to challenging geological conditions.
The India-funded PHEP-I is by far the biggest hydropower project under construction in Bhutan. It is a landmark bilateral cooperation project between India and Bhutan, aimed at harnessing the immense hydropower potential of Bhutan’s rivers. Located on the Punatsangchhu River in Wangdue Phodrang district, this project holds great strategic and economic significance for both countries.
Construction of the concrete gravity dam started in November 2008 and was initially scheduled to be completed by 2015. However, in 2013, a massive landslide on the right bank of the dam site brought construction work to a complete halt.
Now, after 11 years of deliberations and more than 30 meetings of the Technical Coordination Committee (TCC), the governments of India and Bhutan have reached a consensus to resume construction of the dam, Kuensel news website reported on Saturday.
Where is the PHEP-I located?
The project is an environment-friendly, run-of-the-river scheme with its main components located on the left bank of the Punatsangchhu River in Wangdue Phodrang district. The project will utilise a 357-metre head available in a stretch of about 11 km along the river.
The project components along the left bank are easily accessible from the Wangdue-Tsirang National Highway on the right bank. With various project components located between seven km and 21 km downstream of Wangdue Bridge, the Dam site is about 80 km from Thimphu.
Paro, the international airport in Bhutan, is about 110 km away. The nearest railway station is at Hasimara (West Bengal) on the Siliguri-Alipurduar Broad Gauge line of the Northeast Frontier Railway of India. The project area can also be approached from Bagdogra Airport (near Siliguri, West Bengal) via the Phuentsholing-Thimphu-Wangdue Highway (about 425 km) and also via the Gelephu-Tsirang-Wangdue highway.
What is the project’s financing model?
The bilateral agreement between the Royal Government of Bhutan and the Government of India for the implementation of the 1,200 MW Punatsangchhu-I Hydroelectric project was signed in July 2007.
The project was sanctioned for Rs 35 billion and is funded by the Government of India: 40 per cent grant and 60 per cent loan at 10 per cent annual interest, repayable in 12 equated annual instalments commencing one year after the mean date of operation. According to the agreement, the Government of India shall be providing additional funds, as mutually determined, for the completion of the project, in the same proportion and on the same terms and conditions.
The project is owned by the Royal Government of Bhutan but is being developed by the Punatsangchhu I Hydroelectric Project Authority. The authority was formed in 2007 through a bilateral agreement between the Bhutanese government and the Government of India.
Several companies are involved in the Punatsangchhu-I Hydroelectric Project.
WAPCOS (India) Ltd prepared the detailed project report (DPR) for the project. Bharat Heavy Electricals Ltd (BHEL) supplied turbines and electric generators for the project. Spezialtiefbau GmbH provided a diaphragm wall, drilling, and injection work for the project. Encardio-rite supplied, installed, commissioned, and monitored instruments for the project
What happened after the construction was halted in 2013?
According to an article published in Nature Journal in 2020, several slope failures affected the site since 2013, probably as a consequence of the undercutting of a previously unrecognised active landslide.
“Our results indicate that downslope displacement, likely related to the natural instability, was already visible in 2007 on various sectors of the entire valley flank,” the subtract of the article written by Benedetta Dini, Andrea Manconi, Simon Loew and Jamyang Chophel states. “Moreover, the area with active displacements impinging on the dam site has continuously increased in size since 2007 and into 2018, even though stabilisation measures have been implemented since 2013.”
According to the article, stabilisation measures currently only focus on a small portion of the slope, however, the unstable area is larger than previously evaluated. Highly damaged rock is present across many areas of the entire valley flank, indicating that the volumes involved may be orders of magnitude higher than the area on which stabilisation efforts have been concentrated after the 2013 failure.
Though several rectification measures were taken since the landslide in 2013, these failed again in 2016 and 2019, further delaying the project. There were differences in geological interpretations between the two governments that led to disagreements about the necessary stabilisation measures. Now, the Central Water Commission (CWC) of India has prepared the design for the right bank stabilisation measures and submitted it to the Bhutanese government.
“The CWC’s proposal is still under technical review,” the Kuensel report quoted Bhutan’s Energy and Natural Resources Minister Gem Tshering as saying. “We will evaluate if it meets our requirements, and only then will we discuss with the Indian counterparts the adequacy of the stabilisation measures, based on the geological profile of the hill slope.”
Though a consensus has been reached to resume construction of the dam, actual work can only start after rectification work is carried out on the right bank.
Though initially estimated at around Rs 35 billion, the project’s cost has more than doubled due to unforeseen geological issues and an extended construction timeline and is now estimated to be nearly Rs 100 billion.
Why is hydropower a key pillar of India-Bhutan economic cooperation?
Hydropower cooperation is a key pillar of bilateral economic cooperation between India and Bhutan. For Bhutan, hydropower development continues to be a vital catalyst for socio-economic development. Revenues from hydropower constitute a significant portion of the total revenues of the Royal Government of Bhutan.
The ongoing cooperation between India and Bhutan in the hydropower sector is covered under the 2006 bilateral agreement for cooperation and its Protocol signed in 2009. Four hydroelectric projects (HEPs) totalling 2136 MW are already operational in Bhutan and are supplying electricity to India. These are the 36 MW Chukha HEP, the 60 MW Kurichhu HEP, the 1,020 MW Tala HEP and the 720 MW Mangdechhu. Though the 1200 MW Punatsangchhu-I project is facing construction challenges, the 1,020 Punatsangchhu-II HEP is set for commissioning by the end of this year with two of its turbines already operating.
India's imports of electricity from Bhutan amounted to Rs 2,448 crore in 2022, according to the Government of Bhutan’s data. Bhutan’s hydropower potential gives India strategic leverage in South Asia, where it remains the largest economic and developmental partner of Bhutan. Projects like Punatsangchhu-I provide a counterbalance to Chinese investments in other South Asian countries.
Read more: Ahead of Commissioning, Initial Reservoir Filling of India-Funded Mega Dam in Bhutan Done
