Deforestation impacts the water cycle by releasing water vapor back into the atmosphere. Without trees and the other vegetation needed to maintain soil integrity, forested land can quickly become a barren desert that lacks the moisture needed to maintain local lakes and rivers.
The water cycle is a complex system that keeps the Earth's water in a state of continuous circulation. Trees and forested areas play an important role within the water cycle and can be a major factor in determining local climate and precipitation and maintaining the soil conditions that determine streamflow and even area evaporation rates. The loss of a forested areas may have a profound affect on how the water cycle transfers water between the ground and atmosphere on a regional or even global scale.
Trees not only play an important role in maintaining water quality, but they also pass moisture from the soil back to the atmosphere through a process known as transpiration. Trees are also repositories for moisture, with the trees and vegetation of the Amazon rainforest holding more than half the water of the local ecosystem. Deforestation results in faster soil erosion and can result in major disruptions in the runoff needed to replenish local streams and rivers.