Large hydroelectric dams: impacts on biodiversity and indigenous communities, with case studies

Introduction

A large hydroelectric dam submerges a stretch of valley to store water and generate power. Its costs fall heavily on two groups that have little say in the project: the species of the river and the valley, and the indigenous and tribal people who live there.

Impacts on biodiversity

• Lost forest. Large areas of forest and farmland go under water, and with them the plants and animals that depended on them.
• Blocked movement. Dams displace animal populations, damage their habitat and cut their migration routes.
• A changed river. A dam fragments and physically transforms the river, which seriously affects riverine ecosystems. Fishing suffers along with the fish.
• Wider emissions. Vegetation rotting in reservoirs releases greenhouse gases, an impact recognised only recently.

Impacts on indigenous communities

• Displacement out of proportion. Of the 16 to 18 million people displaced by dams in India, 40 to 50 per cent were tribal, though tribal people are only about 8 per cent of the population, taken at one billion.
• Loss of a whole way of life. Large dams have harmed their lives, livelihoods, cultures and spiritual existence, and they have often been left out of the benefits.
• Failed resettlement. Most dam projects have been unable to resettle those displaced, and no ready solution exists.

Case study: the Narmada and Sardar Sarovar

The Narmada River Project has hit the livelihoods of very poor forest dwellers. Poor tribal people have lost their homes and traditional way of life, and fishermen at the estuary stand to lose their livelihood, while rich landholders downstream take most of the economic gain. It is a question of social and economic equity, along with the environmental loss of biological diversity in the flooded Narmada forests. The Narmada Bachao Andolan is India's example of a movement against large dams.

Case study: the Tehri dam

The Tehri dam in the outer Himalayas was sanctioned in 1972, and the textbook's account says that, when finished, it would submerge Tehri town and nearly 100 villages and uproot nearly a lakh people, with little hope of rehabilitation because no alternative land was available. Local people, scientists and environmentalists all opposed it. The emotional cost of leaving a home held for centuries counts as well.

Conclusion

Power from large dams is clean at the point of use, but biodiversity and indigenous people pay a heavy price. Projects need honest impact assessment, real resettlement, and a shift towards smaller dams wherever these can do the job.