Supporters of the usefulness of WFs might also read "Water Footprints: Path to enlightenment or false trail", Ag Water Management, 134, 2014. https://dx.doi.org/10.1016/j.agwat.2013.12.004
Dennis Wichelns analyses are (to me) persuasive in demolishing the usefulness of WFs as a policy guide; my paper adds the further dimension of showing how technically flawed the computational analysis typically is. ET is assumed to be at potential levels; no allowance is made for the ET that would naturally occur in the absence of the crop being assessed. For much of Europe, WFs are actually NEGATIVE -- because the alternative natural vegetation would consume more water than the agricultural crop. the much publicised flooding in the west of England last year was in part blamed on the conversion of woodlands into arable farmland, precisely indication that the crops grown in this areas have a negative footprint.
Tony Allan's original insight that countries make up for severe water deficits by importing "virtual water" was a helpful insight. The subsequent industry of computing tomes of numbers that are (a) wrong and (b) meaningless in policy terms has added nothing further.
Supporters of the usefulness of WFs might also read "Water Footprints: Path to enlightenment or false trail", Ag Water Management, 134, 2014. https://dx.doi.org/10.1016/j.agwat.2013.12.004
Dennis Wichelns analyses are (to me) persuasive in demolishing the usefulness of WFs as a policy guide; my paper adds the further dimension of showing how technically flawed the computational analysis typically is. ET is assumed to be at potential levels; no allowance is made for the ET that would naturally occur in the absence of the crop being assessed. For much of Europe, WFs are actually NEGATIVE -- because the alternative natural vegetation would consume more water than the agricultural crop. the much publicised flooding in the west of England last year was in part blamed on the conversion of woodlands into arable farmland, precisely indication that the crops grown in this areas have a negative footprint.
Tony Allan's original insight that countries make up for severe water deficits by importing "virtual water" was a helpful insight. The subsequent industry of computing tomes of numbers that are (a) wrong and (b) meaningless in policy terms has added nothing further.