Answer: The rivers are one of the biggest contributors to erosion. With its movement, the water manages to break down the rocks and move them away from their initial location. The faster a river is, the more erosion it will cause, and the slower a river is, the lower the erosion it will cause.
The dams are changing the natural process. By constructing dams on the rivers, lakes are formed, the water is becoming is deeper, but also because of the barrier that is set it becomes slower. By becoming slower, the velocity drops down, which in turn means that the power of the water is significantly lower and its ability to break down the rocks and move them away goes down, thus the rate of erosion decreases.
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