The growth of the world's urban population is posing an ever growing challenge to provide city dwellers access to clean water and sanitation, dpa cited a study released Sunday as saying. The World Wildlife Fund (WWF) report - titled Big Cities, Big Water, Big Challenges - was published as delegates assembled for the annual World Water Week in Stockholm. The overriding theme for this year's conference, which opens officially on Monday, is water in an urbanizing world. About half the world's population currently lives in urban areas and by 2050 that portion is projected to be two thirds, the WWF report said, citing the UN Habitat agency. Cities with more than 10 million people are increasing in number in Asia, Africa and Latin America, further straining scarce water resources. The WWF study cited various examples of these pressures. In Mexico City, the risk of flooding has increased as has "the dependence on distant water supplies" and energy costs since the water has to be pumped over 1,000 metres in elevation. The Riachuelo river that flows through Argentina's capital Buenos Aires could be called "an open sewer," the report said, citing levels of lead, zinc and chrome that were well over the legal limit. Over half the population in Kenya's capital Nairobi live in informal settlements, lacking access to clean water and having to buy water from private vendors. They also lack sanitation which threatens their health as well as river systems. In China, Shanghai was suffering from water stress due to the rising demand of its 23 million inhabitants. The report recommended that cities prepare water risk assessments, work to protect and restore ecosytems, and plan how to manage scarce water resources. Later this week, US researcher Stephen R Carpenter is to accept the 2011 Stockholm Water Prize for his research on lake ecosystems. Carpenter's research has helped increase understanding about how lakes are affected by nutrient loading, fishing and the introduction of exotic species, the jury said at an earlier announcement. Last year the 150,000-dollar prize was awarded to US researcher Rita Colwell for her work on infectious waterborne diseases like cholera.
