What are the effects of deforestation?
Many areas of tropical rainforest are burned to provide farmland, but the effects of this deforestation can be disastrous. After the forest is burned, new fertile ground is exposed. But after one or two years this new land is exhausted. The clearing process is repeated, eventually destroying the forest and its wildlife. The bare ground becomes eroded because there is little vegetation to slow the run-off of rainwater. The water strips away the topsoil, dumping it into rivers. The end-result is useless, infertile land that is prone to flash floods. Also, the smoke from burning forests contributes to global air pollution.
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Can rivers run backwards?
In the former Soviet Union, the direction of several rivers was diverted or even reversed to provide water for irrigation. Some of the rivers running into the Aral Sea were diverted northwards in a huge water management project to irrigate land north of the region. In some cases the direction of their flow was reversed. The result was that the Aral Sea began to dry up, because no more river water flowed into it.
Picture credit: google