Originating in Peru, it carries 1,000 million tons of sediment a year into the Atlantic Ocean in Brazil and the patch of brown at its mouth can be seen darkening the South Atlantic in satellite photos. Vast reaches of the Amazon basin are still essentially unmapped and little-known. Massive logging campaigns have dramatically increased erosion and caused international concern that rainforest destruction will contribute to ozone depletion and global warming. While the slow-flowing Amazon has been saved from dam construction, Brazil's official 'Plan 2010' envisages 80 dams on its tributaries. Dams like the Balbina on the Vartna are flooding arable lands, uprooting inhabitants and adding to rainforest destruction.
Watershed stability is threatened by clear-cutting for cattle rearing.
It rises in the Tanglha mountains very near Tibet and flows through Szechwan and Hunan to enter the Yellow Sea near Shanghai. Some of its 600 million annual tons of mud and silt gets deposited on its fertile delta and Chongming Island at the river's mouth. 6 One in 13 people on the planet live in its basin. The Yangtze's dangerous floods have drowned 300,000 people this century alone. For centuries a system of dikes held back floods - some as ancient as the eighth century are still in working order.