Beijing yesterday received its first flows from the South-North Water Diversion Project, one of the most ambitious engineering projects in the country's history, but critics say it will only temporarily quench the city's thirst and will take much-needed supplies from other areas. After decades of planning and at least 202.32 billion yuan (HK$255.45) in investment, more than a billion cubic metres of water is projected to flow north to the capital every year through more than 1,200km of channels and pipes. Another 8.5 billion cubic metres, equivalent to 3.4 million Olympic-sized swimming pools, will reach provinces along the way, according to planners. "Beijing is now formally receiving water" from the scheme, the city's government said in a text message. The authorities say the project, which will ultimately have three routes and cost an estimated US$81 billion, will solve a chronic water shortage in northern cities. Water availability per person in Beijing is on a par with Middle Eastern countries such as Israel, threatening economic growth. Among the engineering feats involved are a 7.2 km-long tunnel beneath the Yellow River, the country's second biggest waterway, described in official reports as the most enormous river-crossing project in human history. To carry the flow over one river in Henan province , engineers built a 12km long aqueduct, claimed to be the longest in the world. But critics say the scheme's success is jeopardised by declining rainfall in the south and it will only act as a temporary stopgap in the north's insatiable demand for water. The north supports nearly half the country's population and economy alongside two-thirds of its arable land, but has just a fifth its total water supply, according to the World Bank. Looking over the Yellow river in 1952, Mao Zedong is reported to have said: "The north of China needs water and the south has plenty. It would be fine to borrow some if possible." At a time when a single word from Mao could launch a project, studies were swiftly begun, but technical concerns and lack of capital meant the idea was shelved until a revival by former president Jiang Zemin , whose government approved the scheme in 2002. Its construction has since taken on added urgency with water levels per person in Beijing falling to just 120 cubic metres, less than Algeria and roughly on a par with Yemen, both desert countries. The project's eastern route, built along the 1,400-year-old Grand Canal, began transporting water from the Yangtze River to Shandong province last year, but has been dogged by pollution concerns and some fear the same fate could befall the pricier central section. China Central Television reported last year that the Danjiangkou reservoir in Hubei province , which will feed the water project, had become a "cesspool" due to the rampant discharge of sewage into its tributaries, with human waste and animal corpses a common sight in one of them. Officials have reportedly closed thousands of factories upstream from Danjiangkou and this year announced that the water was good enough to drink. However, tap water could turn brown in Beijing for a while as new supplies come on stream, the authorities admitted. Zhang Tong, the deputy director of the Beijing Institute of Water, told the Beijing Morning Post that a relatively stable layer of rust inside some metallic pipelines could be washed out by the new water supplies. Liang Li, spokeswoman for the Beijing Waterworks Group, said it would not pose a health risk and residents should keep the tap running until the colour returned to normal. Analysts say the diversion scheme will bring supplies to the north, but the south is now regularly seeing droughts of its own and the new project will exacerbate those strains. "The basic trend in the south is that rainfall decreases each year," said Wu Xinmu, of the Water Research Institute at Wuhan University. The central route has forced the relocation of more than 330,000 people, according to state-run media. But the 1.05 billion cubic metres it is intended to deliver to Beijing every year will still not be enough to end the city's thirst. As the nation's cities become richer, water consumption by citizens has rocketed and is set to grow further. The capital's annual water use has reached 3.6 billion cubic metres and with supplies at only about 2.1 billion cubic metres it already faces a 1.5 billion cubic metre shortfall every year. Environmentalists say water conservation is an urgent priority and prices, currently well below global averages at around 4 yuan per cubic metre, need to rise. A "supply-side approach" exemplified by the project "does not address the underlying causes of the region's water stress", said Britt Crow-Miller, assistant professor of geography at Oregon's Portland State University, who has studied the scheme. "China's current development model is very short-sighted," she added. "It's about keeping things growing at all costs and deferring the consequences as far into the future as possible."