By 2050, more than 1 billion city dwellers may face water shortages if no new infrastructure is built or no new water conservation efforts are undertaken, according to a new study . More than 3 billion may suffer similar water shortages at least one month of every year, says the study. The shortages are projected to hit megacities ranging from Beijing to Delhi, Mexico City, Lagos and Tehran.
The study looks only at water availability within a metropolitan region. Many more people lack access to clean water if problems of inadequate water quality or delivery within cities are taken into account.
To define “water shortage,” the study used a standard of 100 litres per person per day, which the World Health Organization says is the minimum a person needs for “optimum” long-term health and sanitation.
The researchers found that urban population growth will account for most of the big projected increases in water shortage. Climate change may add an additional 100 million more people to live without adequate supplies unless cities take measures on time.
Common infrastructural solutions to address water shortages such as transporting water longer distances, building dams and desalination are all expensive. Better ways to address shortages, says one of the study’s authors Rob McDonaldOne solution, are more efficient water use by agriculture and industry, payments to farmers to reduce areas of irrigated agriculture, and removal of non-native water-hungry vegetation such as eucalyptus.
“The thing I’m really worried about,” says McDonald, “is how the poorest cities are going to be able to afford to get water to their residents. Right now, many poor cities have trouble delivering clean water to their residents, and unless new capital is available for investment the situation will get worse.
“There’s a real shortfall in investment right now in solving this problem, and the developed countries in my opinion need to play a larger role in helping close that shortfall.”
 McDonald, R.I. … [et al.] (2011). Urban growth, climate change, and freshwater availability. PNAS, Published online before print 28 March 2011. DOI: 10.1073/pnas.1011615108 [open access]
Source: Robert Lalasz, Cool Green Science, 28 Mar 2011