NEWS NOTES ON SUSTAINABLE WATER RESOURCES  Large Cities Water Footprint  http://journals.plos.org/plosone/article/file?id=10.1371/jour...

NEWS NOTES ON SUSTAINABLE WATER RESOURCES  Large Cities Water Footprint  http://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0202301&type=printable  Mahjabin T, Garcia S, Grady C, Mejia A , Large cities get more for less: Water footprint efficiency across the US, PLoS ONE 13 (8): e0202301, April 23, 2018.  Many urban indicators and functional citywide properties have been shown to scale withpopulation due to agglomeration effects. We hypothesize that scaling relations may alsoexist for water-related urban indicators such as the water footprint. The water footprint is anindicator of water use that measures humans' appropriation of freshwater resources.   We analyze the scaling of the water footprint for 65 mid- to large-sized US cities using bothempirical estimates and a social interaction network model of city functioning. The networkmodel is used to explain the presence of any scaling exponent in the empirical estimates ofthe urban water footprint by linking to previous theories of urban scaling. We find that theurban water footprint tends to approximately show sublinear scaling behavior with both population and gross domestic product. Thus, large cities tend to be more water footprint efficient and productive than mid-sized cities, where efficiency and productivity are quantified,in a broad sense, as deviations from a linear scaling exponent.   We find the sublinear scaling may be linked to changes in urban economic structure with city size, which lead to large cities shifting water intensive economic activities to less populated regions. In addition, we find that green water contributes to the scaling both positively by transferring the dependence of food consumption on population into the water footprint and negatively by increasing heterogeneity.  Overall, the proposed scaling relations allow for the comparison of water footprintefficiency and productivity of cities. Comparing these properties and identifying deviationsfrom the expected behavior has implications for water resources and urban sustainability.  This study will also be linked on the 2018 Reports Page 02 of the Sustainable Water Resources Site at https://sites.google.com/site/sustainablewaterresources/  Tim SmithSustainable Water Resources CoordinatorGovernment Web Site, https://acwi.gov/Sustainable Water Resources Site, https://sites.google.com/site/sustainablewaterresources/