A Comprehensive Introduction to Water Footprints

Crop water useGreen water use by crop =min (crop water requirement, effective precipitation)Blue water use by crop =min (irrigation requirement, effective irrigation)Green water use refers to the volume of rainwater that evaporates from a cropfield during the growing period. Blue water use refers to the volume of irrigationwater (withdrawn from surface or ground water) that evaporates from a crop fieldduring the growing period. The distinction between green and blue water hasbeen introduced by Malin Falkenmark, Swedish hydrologist.10