'The project is a stop-gap measure at best,' said Patricia Adams, an executive director of Probe International, an independent environmental protection advocacy group. 'Expensive and environmentally damaging infrastructure projects like this will not solve Beijing's water crisis.'

Owing to shortages, the city's per capita water use has dropped by about one-third in the past 20 years, said a report published this year by Probe.

Although Beijing's water consumption in 2008 was about the same as in the late 1980s, its population has grown from 11.5 million to 17 million over the period, it said.

Since 1949, the water available to each person in the capital had fallen from 1,000 cubic metres to less than 230 cubic metres in 2008, the report said, adding: 'Beijing has become one of the world's most water-scarce mega cities with per capita water use now less than one-thirtieth of the world average.'

Although the water shortage in Beijing has long been a problem, 'today, the crisis remains unabated'.

To slake Beijing's thirst, the central government began planning a water diversion project back in the 1950s, but work only began in earnest this decade.

When finished in 2050 it will link the country's four main rivers - the Yangtze River, Yellow River, Huai River and Hai River - through three diversion routes stretching south to north across the eastern, central and western parts of the country.

The project is regarded by some as reminiscent of the construction of the Grand Canal 14 centuries ago during the Sui dynasty, when the enormous expense and forced labour contributed to the downfall of the dynasty in less than 40 years.

The modern idea for a diversion project was mooted by Mao Zedong in 1952. In August 2002, the project was approved by the State Council and work began in December 2002.

In 2001, Zhang Jiyao, an official on the project and former vice-minister of water resources, estimated the cost at 149 billion yuan. Today, those costs have almost tripled to double the 180 billion yuan spent on the world's previous biggest infrastructure project, the Three Gorges Dam.

'The project has tripled in cost in less than 10 years. Are we supposed to believe that for the next 40 years they'll be able to control these costs? All evidence says otherwise,' Adams said.

The resettlement costs of the project had soared because property values had climbed and private developers were paying more in compensation, she said.

Controversial resettlements, especially those involving the Three Gorges Dam, had contributed to making a stronger bargaining position for evacuees, she said.

For the south-north project, 330,000 people living around the Danjiangkou reservoir in Hubei province on the Han River are expected to be relocated by 2014, according to officials.

So far, 87,000 people have been moved or are being relocated, according to Brady Yauch, a Probe International researcher.

The central waterway is intended to supply one billion cubic metres of water to Beijing annually from the Danjiangkou reservoir. Construction began in December 2003 and was originally scheduled to be completed by the 2008 Olympics. However, by September 2008, only 307 kilometres of the 1,267km canal had been completed, according to water-technology.net.

The government then put back the date at which the central waterway would begin supplying water to Beijing to this year, with a further delay announced last year citing 2014 as the start date.

The delay will intensify Beijing's water shortage and accelerate the draining of the city's rivers, reservoirs, water table and aquifers, wrote Wang Jian and Liu Qiong on the Probe International website.

By the middle of this year, 98.9 billion yuan had been spent on the first phase of the eastern and central waterways of the south-north water diversion project, according to the government's website on the project. This comprised 23.2 billion yuan invested by the government, national debt of 10.65 billion yuan, project funds of 33.5 billion yuan and 31.6 billion yuan in loans.

'The Chinese government's track record on implementing major infrastructure projects on time and within official budgets is incredibly poor,' said Adams, pointing to the Three Gorges Dam, which ended up several times costlier than original estimates.

In 2008, the Ministry of Water Resources and the Beijing municipal government announced 24 billion yuan would be spent to tackle the city's water shortage with 136 water projects involving the industrial sector over the next few years.

'More dams, canals, pipelines and desalination plants may be technically feasible but they are economically and environmentally ruinous,' said the Probe International report.

The amount of water diverted from other areas like Hebei and Shanxi provinces has grown from less than 0.5 per cent in 2006 to 8 per cent of Beijing's water supply last year, the report said. 'Beijing has exported its water crisis,' it said.

In Hebei province, the water shortage has become an acute problem, with water resources falling about 50 per cent from their 1950 level, Xinhua quoted Li Qinglin, a director of Hebei's water conservation department, as saying last year.

'Beijing can't keep going further afield, with larger engineering projects to take water from other people's watersheds. Beijing needs to implement regulatory and pricing regimes that reflect the scarcity of water in their own watershed and induce conservation and watershed rehabilitation,' Adams said.

'Resource management by decree leads to massive mistakes. Those are now obvious in Beijing,' the Probe report said. 'The political fixation on large engineering projects to keep urban taps flowing at little or no cost to consumers meant consumption was divorced from consequence without price signals to indicate scarcity.'

Beijing has good laws to protect its water, the report said. 'But without effective enforcement, they are irrelevant at best and an excuse at worst. Though Beijing has much work to do to restore its watershed and live within its water means, the goal is achievable.'

Thirsty capital

Beijing's population has grown but its total water consumption has not

The city's per capita water use has dropped in the past 20 years by about: 33%