Srinagar, Aug. 28 -- By Brahma Chellaney

NEW DELHI-The world's largest dam is rising in one of the world's most geopolitically treacherous and seismically unstable regions. Just a few kilometers from the heavily militarized border with India, China is constructing an unprecedented hydropower project in Tibet on the Yarlung Tsangpo, the world's highest-altitude major river, better known internationally as the Brahmaputra.

The super-dam will dwarf China's Three Gorges Dam, currently the world's largest, in power-generating capacity. Its reservoir will impound a gargantuan volume of water above millions of people downstream in India's northeast and deltaic Bangladesh, much of which lies barely above sea level.

Now the most troubling warni...