How Does Deforestation Affect The Water Cycle?

Transpiration from trees is the main source of water vapor for the water cycles.without trees  an area can become much drier.

Well,

1. Less trees to suck up water.
2. Less trees to keep the ground moist and stuff.
3. It basically throws everything off balance.

Lack of shrubs and trees allows the sun to dry-up the earth more quickly, as the shade shed by protecting crowns of trees or shrubbery is missing. Often small rivulets and springs - that existed while the forest was still intact, will wither away, not even reaching the next greater river.
Trees, and plants in general, affect the hydrological cycle in a number of significant ways:

a) Crowns of trees intercept precipitation, some of which evaporates back to the atmosphere (canopy interception);
b) Their litter stems and trunks slow down surface soil to be blown away by wind or washed away by rain;
c) Their roots create macro-pores - large conduits - in the soil that increase infiltration of water; - deeper down into the earth where it can stay longer to enable more growth -
d) Bush and trees that are cut down reduce soil moisture by transpiration;
e) Litter of trees or bush and other organic matter falling on the ground change soil properties that affect the capacity of soil to store water.

Following this, it is quite obvious that the presence or absence of trees can change the quantity of water on the surface, in the soil or groundwater, or in the atmosphere. This in turn changes erosion rates and the availability of water for either ecosystem functions or human services.

The forest may have little impact on flooding in the case of large rainfall events, which overwhelm the storage capacity of forest soil if the soils are at or close to saturation. Deforestation in mountain areas is known to cause increase in avalanges, earth-slides etc.;