I had the chance to see one of these rivers – and the proposed site of one of the country’s most controversial dams – on a recent trek through the stunning Tiger Leaping Gorge, north of the town of Lijiang in northern Yunnan. On its descent from the roof of the world, the Jinsha River, tributary of the mighty Yangtze, cascades through this ten-mile gorge on its way to Shanghai and the East China Sea.