A water crisis could be the biggest threat to China's rise as a superpower, undercutting the growth and stability so prized by the Government.

Key points: The Yongding River has been dry for 30 years

The Yongding River has been dry for 30 years At its peak, the 700-kilometre river was at least 10 metres deep

At its peak, the 700-kilometre river was at least 10 metres deep The Government's $100 billion South-North Water Transfer Project has been tipped as a solution

In unusually blunt terms, former Chinese premier Wen Jiabao has warned the lack of water threatened the very survival of the Chinese nation itself.

Most of northern China suffers from acute water shortage. The statistics are alarming: in the past 25 years, 28,000 rivers and waterways have disappeared across the country.

The flow of the northern rivers has dramatically slowed or totally dried up.

The iconic Yellow River, the second-longest in Asia, is now a tenth of what it was in the 1940s, and often fails to reach the sea.

The "mother river" of Beijing — the Yongding — used to run long and wide. For centuries it was the lifeblood of the capital, but it has been totally dry for more than 30 years.

On the outskirts of Beijing, all one can see is a massive, sandy riverbed that was once a mighty river.

At its peak, the Yongding River was at least 10 meters deep and the area used to flood. The last big one was in 1958.

The Yongding River Dam, which sits dry. ( ABC News: Brant Cumming )

A dam was built to control and harness the water, but it has never been utilised.

Conservationist Zhang Junheng has walked the entire 700-kilometre length of the river, documenting its demise.

"When I see [the] river without water, it means death," Mr Zhang said.

The dam has never been utilised. ( ABC News: Brant Cumming )

"I searched for reasons — uncontrolled development is one — but the source, the plateaus and mountain ranges, are drying up. There is no water anymore."

Last winter, Beijing endured its longest period without any precipitation, snow or rain — 112 days.

Sitting in the riverbed, Mr Zhang warned it was "inevitable" that Beijing would turn into a desert.

"The rainfall is shrinking and all the rivers are dry; global warming is taking its toll," he said.

Further along the Yongding River, 63-year-old Wang Shuxan is harvesting peanuts. She is one of the few left farming along the riverbanks.

"When I first started farming, the river used to reach the top of the banks [and] children used to drown in the rushing water," she said.

"Now we have to drill to get to water."

For centuries the Yongding River ran long and wide, functioning as the lifeblood of China's capital. ( ABC News: Brant Cumming )

Every year they have to go deeper into the watertable. On average, it is dropping 1 to 3 metres a year around Beijing.

Ms Wang said this season they had to drill down to 70 metres.

Standing next to her, Mr Zhang despaired.

"Once the underground water disappears, what will the people do and how can they survive? No-one is considering this question," he said.

Pollution further compounds the problem.

Government surveys have found that uncontrolled industrialisation and overuse of pesticides and fertilisers have made 70 per cent of China's watertable unfit for human consumption.

Grassroots activists have sprung up, saying the first urgent priority is to communicate the enormity of the crisis to the Chinese people.

Wang Yongchen from the environmental group Green Earth said the Government has to do more.

"It's time the Government places more priority on protecting people and the ecology, not only on economic development," she said.

Government canal systems 'divert other people's water'

The Government said the recently opened South-North Water Transfer Project is the solution.

It has been 60 years in the making, and at a cost of $100 billion, it is the most expensive and biggest engineering project of its type.

The recently opened South-North Water Transfer Project is the most expensive and biggest engineering project of its type. ( ABC News: Brant Cumming )

Water travels from Southern China in the 1,500-kilometre canal for 15 days to get to Beijing. It is a lifeline for the capital, providing about two-thirds of the city's drinking water.

The Government has planned another controversial canal from the Tibetan Plateau.

Wang Yongchen, like many others, said at best it was only a short-term solution.

"Beijing is not so special, why are we diverting other people's water that's also shrinking? We should learn to save water, we only have one Earth."

The canal systems will not be able to satisfy water demands for industry or many northern provinces.

And that is a big problem for state planners as China continues to develop.