Using a newly developed index and our group’s global hydrological model PCR-GLOBWB Yoshi Wada and Marc Bierkens assessed the amount of groundwater consumption coming from non-renewable sources as well as the amount of surface water consumption exceeding environmental flow limits. They calculated that this non-sustainable blue water use exceeds 30% of the current water consumption and that this number will rise to 40% towards the end of the 21st century. When combined with virtual water use, the index, called the blue water sustainability index (BlWSI), can also be used to assess which part of individual products is from sustainable water.
Wada, Y. and M.F.P. Bierkens, 2014. Sustainability of global water use: past reconstruction and future projections. Environmental Research Letters 9, 104003 (17pp).