Forests cover approximately 26% of the world's land surface area and represent a distinct biotic community. They interact with water and soil in a variety of ways, providing canopy surfaces which trap precipitation and allow evaporation back into the atmosphere, thus regulating how much water reaches the forest floor as through-fall, as well as pull-water from the soil for transpiration.

The discipline -forest hydrology- has been developed throughout the 20th century. During that time human intervention in natural landscapes has increased, and land use and management practices have...