Researchers red-flag world’s tallest Pancheshwar dam

| | New Delhi
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Researchers red-flag world’s tallest Pancheshwar dam

Saturday, 11 May 2019 | Archana Jyoti | New Delhi

After locals and environmentalists, it is now researchers including from the government sector who have red flagged the ambitious  5,040-MW Pancheshwar multi-purpose project proposed  on the Kali river bordering northern Nepal and India’s environmentally-sensitive Uttarakhand region.

A pet project of Prime Minister Narendra Modi,  the dam will be the world’s tallest dam (315m high) on completion and is expected to submerge land owned by close to 30,000 families spread over 62 villages in the Hill State. 

After “evaluating risks associated with the project in the light of environmental impact observed for the Tehri  dam in the region and the geological understanding developed over the years”, a team of researchers has called for “re-assessment of its (project’s) geo-environmental implications in the ecologically sensitive Kaliganga valley.”

The study has been published in the recent issue of Current Science. The researchers analysed in detail three major factors related to sediment mobilisation from glacial-paraglacial zones and unstable slopes, infrastructure development and seismicity and their likely impacts. They concluded since there has been no major earthquake in Uttarakhand Himalaya region for long now, the next one to hit this area could be a really big one with magnitude above 8.

The researchers were SP Sati from the Department of Environment Science, Uttarakhand’s VCSG University of Horticulture and Forestry and  Shubhra Sharma, from the Department of Earth and Environmental Science, IISER-Mohali, Naresh Rana from National Centre for Seismology, Ministry of Earth Sciences,  Harsh Dobhal from the School of Media and Communication Studies, Doon University, Dehradun and Navin Juyal, who is associated with the Physical Research Laboratory in Ahmedabad.

Citing various studies, they pointed out that while during the last 100 years, earthquakes of magnitude  more than 7.5 jolted Assam (1950), Bihar (1934) and Kangra (1905), Uttarakhand Himalaya is yet to face high magnitude earthquakes (more than 7.5 on ritcher scale) as being part of the Central Himalayan seismic gap.

“The probability of a high magnitude earthquake in the gap areas is more, yet the precise timing of the earthquake cannot be predicted accurately,” said the researchers as they pointed out that in the Nepal Himalaya most of the hydropower projects are run-of-the river type and lack any major reservoir and yet majority of them were damaged during the 2015 Gorkha earthquake.  Keeping this probable threat in mind, the researchers noted that as the project area lies in Zone IV of seismic zone map of India where various faults around the proposed site are suggested to be currently active, it therefore highlights the increased vulnerability of the site to seismic hazard.

The dam will have a drainage area of  12,000 square km, out of which 2700 square km lies in the glacial and paraglacial zones. The rock fill dam will create a reservoir of 116 square km, out of which 76 square km would be in India. There have been doubts regarding the impact of this project on the terrain and its ecosystem besides concerns on the disruption of the socio-economic conditions of the people living in Uttarakhand’s Pithoragarh and Champawat districts.

Finally, said the researchers, we are yet to develop a reasonable understanding of the behaviour of the Himalayan cryosphere in response to climate variability and changing precipitation trends. “This calls for a complete re-evaluation of the methodology employed for assessing hydropower potentials of the glacial and snow fed Himalayan rivers.

“This is important considering that majority of the hydropower projects are planned in higher Himalaya, implying that these would be sustaining largely on the melt water discharge with subordinate contribution from ISM (as the contribution of ISM decreases northward of MCT).”

 This is also true for Pancheshwar dam project. Recent study from Hindu Kush Himalaya region indicates that a majority of the glaciers has retreated and lost ice mass since the mid-19th century. As a consequence, the melt water contribution into rivers would be adversely impacted, which if, not accounted for, will lead to under-performance of the hydropower project.

Besides locals in the affected region, various green activists and organisations including South Asia Network on Dams, Rivers and People (SANDRAP), a network of organisations and individuals working on issues related to the water sector, have been up in arms against green signal given to the project.

Himanshu Thakkar, coordinator of the SANDRP said, “Seismicity and Reservoir Induced Seismicity(RIS) are not the only hazards that the Pancheshwar Dam faces.

“Key point  is to first assess the inherent disaster potential of the area. The next step would be how the project construction and operation would change the disaster potential of the area and third step would be to assess how the project will perform in these circumstances. None of these are included in the EIA.”

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