Watching Where the Water Goes
"[A] tool developed by the Idaho Department of Water Resources and the University of Idaho is changing the face of water management and conservation by efficiently offering specific measurements of the water consumed across a large region or single field.
Using surface temperature readings from government satellites, air temperature and a system of algorithms, the new method lets officials measure how much water is "consumed" on a certain piece of land through evapotranspiration. Evapotranspiration is a combination of the evaporation of water into the atmosphere and the water vapor released by plants through respiration -- basically, a measurement of the water that leaves the land for the atmosphere, not water that is diverted or pumped onto land but then returned quickly to the water table or river for other users."
By monitoring how much water is naturally reclaimed by the system, researchers can extrapolate how much is being diverted or otherwise used.