Sustainable and efficient allocation of limited blue and green water resources

Freshwater stems from precipitation over land, which differentiates into a blue water flow (groundwater and surface water) and a green water flow (evaporation). Both flows are partially allocated to serve the economy, resulting in blue and green water footprints (WF). There are maximum sustainable levels to the blue and green WF, since rainfall is limited and part of the flows need to be reserved for aquatic and terrestrial biodiversity. Water scarcity, the degree to which the actual approaches the maximum sustainable WF, is becoming increasingly important due to increasing water consumption but limited water availability. The goal of this research is to broaden the discourse on freshwater scarcity in two respects. First, by assessing how Water Footprint Assessment (WFA) for a country can contribute to more sustainable and efficient allocation of blue water resources. Second, by assessing the allocation of the world’s green water resources with respect to maximum sustainable levels.