"Shanghai and the Yangtze river estuary, satellite image. North is at top. Shanghai, visible as a purple-grey conurbation towards bottom left, is one of the largest cities in the world, with a population of around 23 million. The Yangtze river drains much of China, carrying sediment and silt (brown) over 6000 kilometres from the remote, westerly, highland regions of China until it reaches the East China Sea, just above Shanghai."