Case study on river management: Yangtze
The river and the floodplain wetlands it feeds undergo extreme seasonal changes. During the summer rainy season, the swollen waters of the Yangtze flood into the surrounding lake basins, while during winter and spring, when water levels are low, the lakes drain back into the river.
Fish and animals have adapted to these changes and - under natural conditions - move freely among areas connected by seasonal flooding.
Four hundred million people - one-third of China's population - live in the Yangtze basin. The alluvial soil is so fertile that it permits two harvests per year.
In the lower reaches of the river, the abundance of flat land and water has facilitated the growth of densely populated and heavily industrialized cities.
The central Yangtze is known as China's 'home of rice and fish'.