A classic example of a water system severely affected by hu- man development is the Aral Sea, fed by the Amu Darya and Syr Darya. The Aral Sea was once the fourth largest inland body of water in the world, after Lake Superior, supporting 24 unique species of fish and a large fishing population. The Soviet Union built a series of dams and irrigation systems to divert river flows in order to grow cotton on around 3 million hectares of new farmland, but these massive freshwater withdrawals (first order impacts) led to the shrinking of the Sea and a corresponding increase in.
