China has launched construction of a massive hydropower complex on the Yarlung Zangbo river in Tibet. With a projected capacity of 60 gigawatts, it would become the largest dam system in the world, prompting scrutiny from downstream nations that rely on the river. China has launched construction of a massive hydropower complex on the Yarlung Zangbo river in Tibet. With a projected capacity of 60 gigawatts, it would become the largest dam system in the world, prompting scrutiny from downstream nations that rely on the river.