Southern Research Station Headquarters - Asheville, NC
![[Images] Five photos of different landscape](/images/imstr1.jpg "[Images] Five photos of different landscape")
Issue 10
Forests and Water Supply
Water yield can be defined as the difference between the amount of water received from rain and that returned to the atmosphere through evaporation from soil and water surfaces and transpiration from plants. The water supply-and-demand model developed by researchers from the SRS Southern Global Change Team is designed to take into account how much water is evapotranspired (the combination of evaporation and transpiration) and used by forest ecosystems.
“When it rains over a forest, over half of that water will be moved back into the atmosphere, where it will eventually form clouds and come down as rain somewhere else,” says Steve McNulty, leader of the climate change team. “The rest ends up in streams or in deep aquifers—water reservoirs underground. Intact forests supply 40 percent of the municipalities in the United States with water, so the role of forests in water supply cannot be overestimated.”
Forests ensure water quality by slowing runoff, stabilizing soils, preventing erosion, and filtering out pollutants. According to Forest Service data, over 180 million people nationwide depend on forests for their drinking water. Forests and their water systems also provide habitat for unknown numbers of species of animals, plants, birds, insects, fish, reptiles, amphibians, and other life forms.
