The Lower Subansiri Hydroelectric Project

In contemporary times, most dam construction has shifted from the developed to the developing world, with some countries such as China and India implementing large dam construction programmes. The Northeastern region has been identified as India’s ‘future powerhouse’[i] where about 168 large hydroelectric projects have been proposed. These include 22 projects having potential of 15,191 MW in the Subansiri River Basin.[ii] The 2000 MW Lower Subansiri Hydroelectric Power Project, proposed to come up at Gerukamukh on Assam-Arunachal border is the first large hydroelectric project to be constructed in the Subansiri River Basin which in turn is a major part of Brahmaputra River Basin. The large number of projects in the region have the potential to majorly alter the rivers’ patterns and the landscape along it. Therefore, large dams are emerging as a major issue of conflict in Northeast India.[iii]

The Northeast, especially the state of Arunachal Pradesh, where the majority of the dams are due to be built, is a biodiversity hotspot, ecologically sensitive and prone to earthquakes. It is classed as a seismic Zone V – “most dangerous” – by India’s seismologists.^[iv] Similar dam projects have already provoked controversy. For example, the 405 MW Ranganadi Hydro Electric Project built by North Eastern Electric Power Corporation (NEEPCO) in Arunachal Pradesh caused heavy floods during 2004, 2008, and 2011 in downstream Assam which resulted in loss of agricultural land thereby leading to displacement of residents. There is also a perception among the local inhabitants that the benefits of the projects will not be shared with them though they will be subjected to threats to their livelihoods, environment and culture. This has provoled controversy and is a potential source of future conflict.

The issues of dam proliferation in Northeast India started way back in 2001 when Central Electricity Authority (CEA) in its preliminary ranking study of the nation-wide potential for hydroelectricity gave the highest marks to the Brahmaputra River Basin. The Brahmaputra River System includes Barak and other south flowing rivers like Teesta, Subansiri, Kameng, Kalang, Dihang, Dibang and Lohit. The Brahmaputra is one of the world’s largest rivers, with a river basin of 5,80,000 sq.km of which 33 percent is in India.[v]

As far as the Lower Subansiri Hydroelectric Power Project is concerned, after completing 50 percent of the work, the National Hydroelectric Power Corporation (NHPC) is in a dilemma over the project. In the past seven years, at least six expert committees have raised alarm on the dam’s safety and its possible impact on downstream areas. The latest is a technical experts’ committee of the Planning Commission, set up in January 2011. The committee, comprising former bureaucrats with the Ministry of Water Resource is of the opinion that the project is not scientifically and technologically viable and calls for a major overhaul in the design. Construction remains stalled at the project since May 2012 due to frequent protests and strikes.

Geological concerns also abound as the dam rests on a weak foundation - Shivalik Sandstone, which has a poor strength of 12 to 20 Mega Pascal (MPa) in dry condition and 4 MPa in the presence of moisture. To give an idea, light hammer blows could break anything between 12.5 MPa to 50 MPa, while applying hand pressure could break a stone less than 4 MPa.[vi] In addition to this geological shortcoming, the people of Assam have been fighting for several years against a proposed gargantuan network of dams across the upper reaches of its rivers in Arunachal Pradesh. The anti-dam convulsion in Assam, especially the one against the Lower Subansiri project, has a decade-long history. As the riparian anxiety and the uncertainties about its social and ecological impact grew, the All Assam Students Union (AASU) started campaigning against the mega-dams in 2002. At the same time, a few other NGOs joined the rally and held protest marches. AASU views this campaign not only as an issue in Assam, but part of a wider pan-Northeastern struggle. For that matter, their movement does not limit itself to Lower Subansiri Hydroelectric project, but also encompasses the environmental concerns of other projects such as the Tipaimukh dam on the Barak River in Manipur, or the Kurichu dam in Bhutan.

The Lower Subansiri Hydroelectric Project is a Run-of-the-River (RoR) power station. The Bureau of Indian Standards (BIS) Code IS: 4410 defines a RoR Power Station as “a power station utilising the run of the river flows for generation of power with sufficient pondage[vii] for supplying water for meeting daily or weekly fluctuations of demand. In such stations, the normal course of the river is not materially altered.”[viii] However, analysts have argued that most of the so called RoR hydroelectric projects being developed in the Himalayan region involve large dams which divert the river water through long tunnels before the water is dropped back into the river at a downstream location after passing through a powerhouse. These projects are promoted as being ‘environmentally benign’ as they involve smaller submergences and lesser regulation of water as compared to conventional storage dams. However, as these projects also involve extensive tunneling in a geologically fragile landscape, they have an adverse environmental and social impact that is generally not considered. As an example, the Lower Subansiri Hydroelectric Project will have a ‘dam-toe’ (another type of RoR) powerhouse located immediately downstream of the dam just before entering the plains in Assam. Further, the reservoir of the Lower Subansiri Hydroelectric Project will submerge a 47 km length of the Subansiri River, which will cause drastic daily fluctuation in river flows downstream due to power generation patterns, particularly in winter. This will massively alter daily flow patterns, which in turn will have serious social and environmental impact on the Brahmaputra floodplains.

The movement has attracted the support of all sections of civil society in Assam. In a region where politics is premised on the metaphorical poetics of a river as the lifeline of a nation, the anti-dam mobilisation is here to stay.[ix] The dam, such as the Lower Subansiri Hydroelectric Porject without doubt, could turn the downstream valleys into a desert. But if they collapsed, an apocalyptic flood could swallow all in its path. The concern over dam building in the Brahmaputra River Basin, emanates not only from the likes of Lower Subansiri Hydroelectric Project, but also from China’s plans to dam the Yarlung Tsangpo (Brahmaputra River). The Zangmu Dam is just the first of 28 dams that China plans to build on the Yarlung Tsangpo in Tibet, including a hydel power generation plant at Zangmu on the middle reaches of the Brahmaputra River, less than 200 km from the Indian border. The issue of more serious concern to India is China’s plans of diverting the Brahmaputra River. Since the Brahmaputra originates in Southwestern Tibet as Yarlung Tsangpo with 56.5 per cent of the river’s length and 50.5 percent of the area of the drainage basin, the diversion of the Brahmaputra River will imply environmental devastation of India’s Northeastern plains.^[x]

While Northeast India can be the ‘powerhouse’ of India, environmental concerns need to be taken into account. This should also include agreements on sharing of natural resources like water with its foreign neighbours. Therefore, projects like Lower Subansiri Hydroelectric Project should be executed with due consideration of the scientific viability of such projects while addressing the implications that such projects will have in the livelihood and cultures of the inhabitants along the natural resource.

The author is a Research Assistant at CLAWS

Views expressed are personal