The Himalayas, the world's highest mountain range, may soon hold another record: it could become home to the greatest density of dams in the world. More than a thousand are either already operating, under construction or being planned in northern India, Nepal and Bhutan. Besides providing clean energy, they could improve flood control and access to drinking water. But they will also pose a serious threat to indigenous species.
Hydroelectricity supplies about one-fifth of India's power, but even so nearly 300 million of the country's inhabitants have no access to electricity. More dams could help plug the energy shortfall: India's hydropower potential is estimated to be four times its current production of 39 gigawatts.
Maharaj Pandit at the University of Delhi, India, and R Edward Grumbine at the Chinese Academy of Sciences in Kunming, have now studied the impact 292 of the planned Himalayan dams will have. They used satellite imagery and published data on Himalayan species richness to estimate how each dam's location would affect forest cover and biodiversity.
"We project that about 1700 square kilometres of forests would be submerged or damaged by dams and related activities", says Pandit. He and Grumbine predict that such deforestation will result in the likely extinction of 22 flowering plants and 7 vertebrate species by 2025. This number would rise to 1505 flowering plants and 274 vertebrates by 2100 if construction work continues.
Another recent study suggests the dams will be bad news for many of the Himalayas' 300 species of fish. Jay Bhatt and colleagues at the University of Delhi studied distribution of fish species in 16 Himalayan rivers, and found that those richest in biodiversity, with the greatest number of endemic species, were also those where dams will be concentrated.
"Dozens of dam projects are already caught up in litigation due to faulty environmental impact assessments, displacement of people, inadequate compensation, destruction of traditional water and livelihood sources, and loss of biodiversity," says Himanshu Thakkar, coordinator of the South Asia Network on Dams, Rivers & People, an informal group of organisations and individuals interested in the impact of dam-building. The combined effect of several hundred new dams would be gargantuan, he adds.
Journal references: Pandit and Grumbine study: Conservation Biology, doi.org/j3z; Bhatt study: PLoS One, doi.org/j3x
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