Home Magazines Conservation Are Big Dams Leaving India High And Dry? By Neeraj Vagholikar

Are Big Dams Leaving India High And Dry? By Neeraj Vagholikar

Are Big Dams Leaving India High And Dry? By Neeraj Vagholikar

April 2011: The author is one of India’s most knowledgeable experts on the impact of large development projects such as dams and  mines on ecosystems and people. He has travelled extensively across India and has been reporting and writing for Sanctuary for over 15 years. He writes here of India’s planned destruction of the Brahmaputra valley.


The Lower Subansiri project under construction on the Assam – Arunachal Pradesh border. After the commissioning of the 2,000 MW project, flows in the Subansiri river in the downstream (in winter) will fluctuate drastically on a daily basis from six cubic metres per second (cumecs) for around 20 hours (when water is being stored behind the dam) to 2,560 cumecs for roughly four hours when the water is released for power generation in the evening. – Neeraj VagholikarOn a sunny January morning this year, I was in the vast floodplains of the river Siang in Arunachal Pradesh (AP). The river is called Yarlung Tsangpo in upstream China and enters downstream Assam to form the Brahmaputra after its confluence with the Lohit and Dibang rivers at a unique tri-junction. Accompanied by local friends, I was on a small country boat crossing over to one of the riverine islands in the midst of the braided river, 30 to 35 km. downstream of the proposed 2,700 MW Lower Siang hydroelectric project in the highlands upstream.


Further east, contiguous riverine islands and tracts – a mix of grasslands, wetlands and forests – form part of the Daying Ering Wildlife Sanctuary, an area which has been identified as an Important Bird Area (IBA) and a potential Ramsar site by the Bombay Natural History Society (BNHS). The area is also home to the tiger and wild water buffalo, and serves as a vital elephant migration corridor.




As we moved downstream, our boatman, Bhudan Sahni, pointed to a wooden post on the right bank of the river, which rose well over 300 cm. (10 feet) above the water level. Bhudan said this was put up by the proposed Lower Siang project authorities to indicate the height to which the water levels will rise when the turbines of this mega project turn each evening to generate ‘peak load’ electricity. Official data suggests that in the winter months downstream waters would recede to 25-30 per cent of normal flows for 20-21 hours each day as the dam is filled and then rise to 500-600 per cent of normal flows for three to four hours when power is generated.


In January, for instance, the flow would fluctuate between 328 cumecs (cubic metres per second) and 5,063 cumecs on a daily basis, as opposed to a uniform flow of approximately 800-1,000 cumecs in a no-dam situation. Where we were and in the neighbouring tracts of the Daying Ering Sanctuary, this would translate into an unnatural daily fluctuation of around four metres (over 13 feet) by the company’s own admission.


The natural flow pattern of a river is like its ‘heart beat’ and the alternate starving and flooding of  the Siang by the proposed Lower Siang hydel project would leave critical floodplain ecosystems in the downstream and their inhabitants  ‘high and dry’ – literally!




The downstream impacts of dams in the Brahmaputra river basin has been an issue of major concern in recent years in Assam and Arunachal Pradesh, even as plans unfold to develop as many as 135 large hydropower projects to produce approximately 57,000 MW of electricity in Arunachal Pradesh alone. When large dams block the flow of a river, they also trap sediments and nutrients vital for fertilising downstream plains. They alter the natural flow regimes which drive the ecological processes in the downstream areas. The fragile and magical connection between the upstream and downstream waters is disrupted by large dams, with a disastrous effect on the economy of people in the floodplains whose lives have been tailored to river flows.


Some downstream impact concerns in the Northeast include: loss of fisheries; changes in beel (wetland) ecology in the floodplains; impacts on agriculture on the chapories (riverine islands and tracts); impacts on various other livelihoods due to the blockage of rivers by dams (e.g. driftwood collection, sand and gravel mining); increased flood vulnerability due to massive boulder extraction from river beds for dam construction and sudden water releases from reservoirs in the monsoons; dam safety and associated risks in this geologically-fragile and seismically-active region.




The drastic daily fluctuation in river flows will be seen virtually across all major rivers such as the Subansiri, Dibang and Lohit in the Brahmaputra river basin. For example, the average winter (lean season) flow in the Subansiri river in its natural state is approximately 400 cumecs. Both the ecology of the downstream areas and people’s use of the riverine tracts in winter is adapted to this ‘lean’ but relatively uniform flow of water on any particular day. Chapories for example, which are exposed and drier in winter, are used by wildlife, as well as for agriculture and cattle grazing purposes by local communities. After the commissioning of the 2,000 MW Lower Subansiri project, flows in the Subansiri river in winter will fluctuate drastically on a daily basis from six cumecs for around 20 hours (when water is being stored behind the dam) to 2,560 cumecs for around four hours when the water is released for power generation in the evening hours.


The floodplain of the Brahmaputra and its major tributaries will become exceedingly dangerous for people and animals such as elephants, tigers, wild water buffalos, hog deer and river dolphins due to upstream dams. – Dhritiman MukherjeeIn other words, hydropower projects technologically lend themselves to be operated as peaking power plants, but this ruins downstream ecology. This can be pictured another way. Peak load water releases in the Subansiri river in winter will mimic the average monsoon flows, causing ‘winter floods’ every single day! The impact on both people and wildlife can be imagined! Fishing, flood-recession agriculture (such as mustard), river transportation and livestock rearing will all be adversely affected and the floodplain will become exceedingly dangerous for people and animals.




The chapories of rivers such as the Lohit, Dibang and Siang are home to a variety of grassland flora and fauna. These house several IBAs and potential Ramsar sites. There is a presence of a number of globally threatened avian species such as the Bengal Florican (global population less than 500), Swamp Francolin, Lesser Adjutant and the White-winged Duck, besides a number of other grassland and wetland birds. Many of these birds including the critically-endangered Bengal Florican and vulnerable Swamp Francolin breed in the grasslands in the chapories and lay their eggs on the ground or reed beds. Their breeding is seasonal and is dependent upon ground moisture and the status of grasslands and swamps in January, February and March, the prime mating and egg-laying months when the habitat is ‘dry’. Hatching and rearing takes place early-April onwards.


Wildlife biologist and grassland expert Dr. Goutam Narayan reiterates:


The massive flow fluctuations in winter in the downstream reaches of hydropower projects in the Eastern Himalayan foothills will be catastrophic, particularly for ground flora and fauna. Mammals, birds, reptiles and amphibians that live on the ground of these chapories will be severely affected and some of them will either be drowned or obliterated. The eggs or young ones of the breeding animals will suffer badly. Normally these chapories do experience seasonal flooding due to change of river flow in rainy season, but at those times most of the animals move away to drier areas. In the dry season there is no flooding for several months and this is the time when most of these birds and animals occupy these chapories and often breed there. The massive increases in water flow for a few hours even in the dry season will cause daily floods in large parts of these low-lying chapories. The behaviour of ground breeding birds, reptiles and mammals is not adapted to this level of daily flooding in the breeding season. Remnant populations of highly threatened species like the Bengal Florican and Swamp Francolin will certainly lose even these tiny pockets of suitable habitat surviving only because they are so inaccessible and remote.


Other wildlife impacted by flow fluctuations would include the tiger, elephant, wild water buffalo, hog deer and Gangetic river dolphin. Many are likely to be washed away due to sudden rises in water levels to which wildlife is not adapted. The Subansiri is only one of two tributaries of the Brahmaputra that have a resident population of the Gangetic river dolphin. Scientists from the Dibrugarh University as well as conservation groups from Assam have raised concern about the serious impacts on the national aquatic animal due to massive fluctuation in water levels once the under-construction 2,000 MW Lower Subansiri hydroelectric project is operational.


Biologist and fish expert Lakhi Prasad Hazarika who has been involved in extensive studies on the Subansiri river says, “Particularly vulnerable due to these flow fluctuations are fish in the transition zones in the foothills. For example, in the winter, some species breed in the shallow waters (Barilius species), while others such as the golden snake head Channa burca and Channa orenmacunatus hibernate along the shorelines. Such massive flow fluctuations will destroy these natural processes for many such species.




While the 2,000 MW Lower Subansiri project is currently under construction amidst strong protests downstream, projects on all major rivers such as the Siang, Dibang, Lohit and Manas are undergoing various stages of “green clearances”. The decision-making process at the Ministry of Environment and Forests (MoEF) in New Delhi is in denial of a basic fact of nature – that a river flows downstream. After widespread protests in Assam, the MoEF and its Expert Appraisal Committee (EAC) on River Valley and Hydroelectric projects have in recent months finally acknowledged downstream impacts but we have no indication that this will lead them to act with courage and intelligence.


The chapories (riverine islands and tracts) of rivers such as the Lohit, Dibang and Siang are home to a variety of grassland flora and fauna. These house several IBAs and potential Ramsar sites. Vast tracts of wetland, grassland and woodland ecosystems will be adversely impacted due to drastically altered flow patterns caused by the over 135 large hydropower projects planned in Arunachal Pradesh. – Dhritiman MukherjeeFor example, the 1,750 MW Demwe Lower project on the Lohit river was granted environmental clearance in February 2010 ignoring downstream concerns after which a post-clearance downstream impact study is being conducted! Similar post-clearance studies were earlier commissioned for the 2,000 MW Lower Subansiri and 1,500 MW Tipaimukh projects in the region. These acts, which are clothed with language such as ‘pragmatic’ will be judged by future generations as nothing short of criminal. Hopefully pending forest and wildlife clearances for the Demwe Lower project will not follow in the same fatal footsteps, especially since the project is upstream of sensitive wildlife habitats in the Lohit floodplains. Hydropower projects in the Northeast cannot be treated as a fait accompli and need to be reviewed in light of this serious lacuna – downstream impacts.


Recently the MoEF, for the very first time, prescribed partial downstream impact studies for a handful of projects before granting environmental clearance (3,000 MW Dibang Multipurpose project and 2,700 Lower Siang). But the Terms of Reference in these cases were so sketchy as to be a recipe for dam-related conflicts. Worse, consultants hired by project developers continue to produce all reports, not surprisingly, in favour of their own projects.


Cumulative impacts of multiple projects (including in the downstream floodplains) assumes great significance in the region as over 135 hydropower projects are in the pipeline in Arunachal Pradesh alone. However, though cumulative impact assessments have been commissioned in some of the river basins recently, the environmental clearances of individual hydropower projects in such basins have been specifically de-linked from the results of such cumulative studies, rendering the whole exercise meaningless.




Thus far discussions in MoEF’s EAC have primarily centred around addressing the ‘dry’ part of the flow fluctuations. This has involved exploring the possibility of keeping one turbine running through the day to reduce the effect of starving the river of water for approximately 20 hours prior to peak load water releases. But as mentioned above, one of the most severe downstream impacts will be the unnatural high flows when power is generated. In the Lower Siang project, EIA consultants hired by the developers have laughable, ecologically illiterate, ‘fixes’ to manage downstream impacts on the Daying Ering Sanctuary. They want to build walls around low lying islands! Incredible. The walls will, of course, merely add to wildlife woes when the river levels are both high and low. 


Another idea discussed in the EAC that was rejected for its impracticability was the creation of ‘balancing reservoirs’ downstream of projects such as the Lower Subansiri dam.  Theoretically these reservoirs are meant to absorb the fluctuating flows from upstream powerhouses so as to mimic natural flow patterns. But such techno-fixes, though they sound possible, cannot solve the social and environmental risks of these ill-advised mega dams in the ecologically and geologically fragile, seismically active and culturally sensitive Eastern Himalayas.


Experts from IIT Guwahati, Dibrugarh University and Guwahati University who conducted a downstream study of the under-construction 2,000 MW Lower Subansiri project have opined that the dam is unviable on geological grounds alone.


A third option to address the impact of fluctuating downstream flows might have been to run turbines according to natural flow patterns or allow a minimal departure of flow from natural flow patterns. But this ‘solution’ would render the projects economically unfeasible say economists. So why are the dams being constructed despite such insurmountable problems? Because developers, particularly private developers, are counting on huge anticipated profits from the generation and sale of power at very high prices during the peak load period in the open market (called ‘merchant sales’).


Common sense suggests that the long-term ecological and social security of the ecologically-sensitive floodplains in the Brahmaputra river basin demands that the mega projects being planned on rivers such as the Subansiri, Siang, Dibang and Lohit must be shelved. Smaller projects on their tributaries examined and built on a case-by-case basis, could deliver power to every single family in the Northeast. But that is not and never was the objective of economists, developers and politicians living in far away New Delhi. Their objective is to cash in instantly by superimposing short-term commercial infrastructure on long-term natural infrastructure of the people of the Northeast, leaving millions, literally, high and dry.


by Neeraj Vagholikar 


The author is a member of Kalpavriksh and a Panos South Asia media fellow 2010-11.


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