The number of large cities prone to insufficient water supplies could increase over the next 25 years — even without accounting for climate change.

Julie Padowski and Steven Gorelick at Stanford University in California used projected urban population growth and increasing agricultural demands to assess changes in water needs. They focused on 71 cities around the world that depend on water from surface rivers or reservoirs, and estimate a 28% increase in the number of cities that will suffer supply vulnerability in 2040 compared with 2010. Among the most vulnerable are Ouagadougou, Burkina Faso; Guangzhou, China; and Dublin, Ireland.

Redistributing water from agriculture and from other non-urban areas could mitigate water shortages, the duo says.

Environ. Res. Lett. 9, 104004 (2014)