The Three Gorges Dam in central China is famous as the world's largest dam project by far. When it was completed in the early 2010s, it could handle more than a tenth of the electricity supply for a country of about a billion people.
Over a trillion
But even that mega-construction pales in comparison to Yaxia, also known as Medog or Motuo. Prime Minister Li Qiang was on site in eastern Tibet this summer for the symbolic groundbreaking of a hydroelectric project budgeted at over a trillion yuan (at least 1,400 billion kronor) - equivalent to about the entire Swedish state budget.
When Yaxia is completed in less than ten years, the plant will be able to generate 60 gigawatts. That's as much power as 60 normal nuclear reactors.
The construction is taking place in very sparsely populated mountainous regions, along the Yarlung Tsangpo River, whose sources are in the glaciers of the enormous Tibetan Plateau. But further downstream the river continues into India, where it is called the Brahmaputra or Siang, and then Bangladesh, which calls it the Jamuna.
Called South Tibet
Chinese authorities assure that this does not pose any problems - once the water has flowed through Yaxia's turbines, it is released as usual.
"China has never had, and will never have, any intention to exploit transboundary hydropower on rivers to pressure downstream countries," it said in a statement to the AFP news agency.
But the world's two most populous countries - every third person on earth is Indian or Chinese - do not always have good relations, especially in these mountainous regions. The closest downstream region from Yaxia is Arunachal Pradesh, which serves as India's northeasternmost state but is also claimed by China, and China calls it South Tibet.
11 gigawatts
The regional Indian government chief there, Pema Khandu, has described it as "necessary for national security" for India to take countermeasures. And one such measure is new plans for an Indian dam in Arunachal Pradesh.
India's dam is in the early stages of planning, but is expected to have an output of over 11 gigawatts. It would be a substantial and relatively environmentally friendly addition to India's dirty, coal-dependent electricity system. But that is not the main purpose, admit sources at the state-run power company National Hydropower (NHPC).
It will address water security and flood risks - in case China weaponizes its dam and uses it as a "water bomb," a senior official told AFP on condition of anonymity.
Agreement on hold
India has its own experience of using river water in conflicts. After a bombing in Indian-held Kashmir this spring, "Narendra Modi’s government put a 1960 water agreement with Pakistan on hold and restricted water supplies from the Chenab River to the neighboring country’s farmers," writes Indian political commentator Pranay Sharma in the Swedish magazine Utrikesmagasinet.
He also quotes Brahma Chellaney, professor emeritus of strategic studies in Delhi, who warned earlier this year that the water dispute threatens to "evolve into a slowly unfolding environmental disaster that threatens water availability, ecological balance and geopolitical stability across the Asian continent."
Much of the Earth's freshwater is stored in glaciers on the Tibetan Plateau, also known as the "roof of the world," in Central Asia. The plateau is more than five times the size of Sweden and has an average elevation of about 4,500 meters above sea level.
Meltwater flows down from the plateau and forms several of the world's most famous and important rivers, such as the Yellow River and the Yangtze in China, the Mekong, which flows through Thailand and Vietnam, the Irrawaddy in Myanmar, and the Indus and Brahmaputra in Pakistan, India and Bangladesh.
In total, this water reaches several billion people - one fifth of the world's population is estimated to be more or less dependent on water from the "roof of the world".
