How do trees and forests prevent floods?

Answer 1

Answer

They don't. If the ground level is low enough, a flood can occur regardless of what is on the ground. They can help prevent mud slides though. Their roots help hold the soil together.

additional info:

It helps through falling leaves, these leaves serve as a giant sponge which controls the water to flow in lower level areas.

Answer 2

Forests prevent soil erosion and floods . Roots of trees help to control soil erosion as roots bind the soil particles together and prevent the soil from being washed or blown away.