Destruction of the rainforests wipes out 17,000 plant and animal species each year,most of whom are unique to the area. By destroying the rainforests, humans are snuffing out 50 million years of continuous growth and evolution. On The Water Deforestation leads to erosion which causes massive amounts of silt to wash downstream. The silt clogs canals and dams causing river beds to rise and possibly flood. Flooding and soil and water degradation caused by tropical deforestation periodically disrupts the lives of approximately 1 billion people.
Tropical rainforests provide a natural defense against hurricanes, cyclones, and typhoons.
Because of deforestation, storm damage costs have increased 6 fold in the last 20 years. A single tropical storm can wash 70 tons of soil into a river. Rainforests absorb nearly half of the Earth's rainfall and gradually release it into the rivers and streams. Therefore, when rainforests are intact, the rivers run full and clear. However, when the forests are destroyed, the rivers dry up and become muddy.