China has begun construction of what is set to become the world’s largest hydroelectric station, built along the Yarlung Tsangpo river in southeastern Tibet. The project carries an estimated cost of around 170 billion dollars.
The station is expected to generate roughly 300 billion kilowatt-hours of electricity per year, nearly three times the output of the Three Gorges Dam.
The announcement has drawn renewed attention to a 2005 NASA study. Geophysicist Benjamin Fong Chao found that filling the Three Gorges reservoir on the Yangtze River, which held about 44 billion tonnes of water, shifted enough mass to increase Earth’s day by approximately 0.06 microseconds and move its rotational axis by around two centimetres. Later research suggested the combined effect of thousands of dams worldwide may have shifted Earth’s axis by close to one metre over recent decades.
Physicists say they cannot yet determine whether the new dam will produce a measurable effect on Earth’s rotation.
The project also raises environmental concerns. Downstream, the Yarlung Tsangpo becomes the Brahmaputra, flowing through India and Bangladesh. Experts warn that altering the river’s flow could affect fish migration, sediment transport, and seasonal flooding for millions of people.
