A global perspective on changing sustainable urban water supplies

Ensuring the sustainable supply of water for the world's largest cities has been and is a current challenge. Future trends in urban water consumption patterns will be determined by changes in population concentration, per-capita water use, climate, and the proportion of water retained for the production of instream ecosystem services. The objective of our research was to identify patterns of renewable water availability and urban consumption throughout the globe between the years 2000 and 2015. To better understand the interactions between urban consumption and regional availability of renewable water we used a modified ecological footprint (EF) approach. Urban water footprint areas were differentially sensitive to changes in consumption and changes in water availability; our results suggest climate induced reductions in water availability may be more of a concern than population growth or increased per-capita for securing continued supplies of water to large cities. Our results provide a comprehensive description of global urban water demand and highlight the variation between consumption and availability relationships for the 524 largest cities.