On Feb. 19, the U.S. Geological Survey (USGS) announced that it has mapped long-term evapotranspiration rates across the continental U.S. for the first time. Evapotranspiration is water that is lost to the atmosphere via evaporation and plant transpiration, and it has a large impact on water availability. According to USGS, half of annual rainfall is consumed by evapotranspiration. The map will aid modeling efforts and enable water managers to make sounder, science-based decisions.
The evapotranspiration map is based on data from 1971 to 2000 and includes climate and land-cover data from Landsat satellite imagery, as well as streamflow data from more than 800 watersheds. Using this information, researchers generated a mathematical equation to more precisely estimate long-term evapotranspiration at any location in the continental United States. Read more.