Assessment studies for dam and hydropower projects in India attempt to look closely at the impacts of river-inhibiting civil works, but the full impact of tunneling is often evaded, or at best understated. This is just one reason why run-of-river hydropower projects (HEP) are wrongly labeled relatively benign as compared to reservoir dam-toe HEPs.
The Himalayan mountains are littered with run-of-river projects, most of which start at a weir, barrage or dam across a river. The water is then diverted to a tunnel, bored through the mountainside, typically several meters in diameter. For large projects, above 25-megawatt capacity, the shaft runs within the mountain, with a minimal gradient, while the river descends with a steeper gradient towards the plains. Lengthier the tunnel, often more than 10 kilometers, greater the height differential and thus pressure in vertically downward delivering water to run one or more turbines.
In this megawatts game, the hardships braved by the resident population are often ignored, with more than 100 families directly affected in some cases. Houses develop cracks, while water sources dry up. We observed this time and again in the West Sikkim hills, a northern Indian region we visited April 20th through the 28th earlier this year. Throughout the West Sikkim Hills and other Himalayan states, bumper-to-bumper hydropower projects are not only planned but under construction.
The West Sikkim hills serve as the catchment for the Rangit River, a major right-bank tributary of the Teesta, which drains towards the Bay of Bengal. Although there is only one commissioned HEP in the basin, projects under construction (some presently abandoned or stalled), with their several-kilometer-long tunnels, are impacting the flow of streams, a source of drinking and irrigation for hundreds and thousands of villagers in the Rangit River basin. Many perennial streams in the area are now either dry or shadows of what they used to be.
India’s Ministry of Environment and Forests requires that Environment Impact Assessments of hydropower projects include: “Adverse impact on land stability, catchment soil erosion, reservoir sedimentation and spring flow (if any) due to (a) considerable road construction/ widening activity (b) interfere of reservoir with the in-flowing streams (c) blasting for commissioning the HRT (headrace tunnel), TRT (tailrace tunnel) and some other structures should be studied.” But such reports often underestimate those impacts.
Many villagers have lodged protests with government agencies, project developers, and media. In one case, residents of the village ‘Middle Sumin’ filed a public interest litigation to stop construction of a 12 km long tunnel. Madhya Bharat Power Corporation, a private developer implementing the 97 MW Rongnichu HEP, is building the tunnel. The villagers claim that the tunnel has impacted houses, fields and their water sources. A 2013 report by the Department of Mines, Minerals and Geology recognized the loss of a perennial stream in the area. The case went to the Supreme Court of India, where the petitioners have requested the state government to carry out a study on how the tunneling impacts wildlife, seismicity, and water supply in the region.
We also spent an entire day hiking in the nearby hills overlooking the 97 MW Tashiding hydroelectric project (HEP) on the Rathong Chu River, a major tributary of the Rangit. In 1994, the state government of Sikkim expressed concern over a 30 MW project, up-river from where we were positioned, on religious grounds. Protests by activists and monks led the state government to scrap the project in 1997. It was then argued that no other project should be allowed on the sacred river. Two other upstream projects, the 96 MW Lethang and 99 MW Ting Ting HEP, were subsequently scrapped.
Yet, construction on the Tashiding HEP is now in full swing. The coffer dam, around 100 meters downstream from the confluence of the Rimbi and Rathong Chu Rivers, has diverted water temporarily for the barrage to be built. Since work began on the tunnel, consequences for the adjacent hillside villages have become apparent. In Singertam village, a 45-minute hike from the nearest road, many walls cracked from the impact of blasting into the hillside. Villagers received no compensation or help with reconstruction. Some abandoned their homes, while others did their own repair work. Some villagers even kept the cracks in their walls to serve as reminders to the project developers. Their paddy fields have mostly dried up, due to the altered path of natural mountain streams. The villagers also point out that blasting and tunneling work in the area has caused land subsidence.
A long tunnel in the upper reaches of a river that hurtles to the plains creates potential for considerable energy generation. But such run-of-river hydropower projects have serious impact on nearby residents’ quality of life. To conduct meaningful Environmental Impact Assessments, Indian government agencies, along with their counterparts in other regional Himalayan nations, must take into consideration such concerns raised by project-affected people.
International Rivers’ South Asia Team and our partner organizations continue to collect a growing body of anecdotal evidence from different parts of the Himalayan region. For a blog and photo essay capturing the impacts of tunneling in Kinnaur district of Himachal Pradesh, click here. For an essay of impacts from the same state, click here. Such impacts are braved by project affected poeple in river basins across the length and breadth of the Himalayas.