BEIJING, Dec. 28 -- Water through the south-to-north diversion project has arrived in Beijing on Saturday after a journey of over 1,200 kilometers, bringing with it a torrent of doubts and worries.

Mao Wei, a resident from a community in Tongzhou District of Beijing, never expected he would benefit from a project conceived by late Chinese leader Mao Zedong, who shares the same family name with him, more than 60 years ago.

But Mao Wei has his own concerns over water from the Hanjiang River, a tributary of the Yangtze River, China's largest waterway.

"It's no difference," said Mao, "but I feel worried when people warned on the Internet that the water may become yellow due to poor quality."

In order to eliminate public concern, Beijing Waterworks Group has sent out educational leaflets. It said if the water becomes yellow, the public does not need to be worried because it is due to a high density of iron ions and will not affect people's health.

The middle route's first-stage project starts at Danjiangkou Reservoir in the central province of Hubei. It was officially put into operation on Dec. 12..

Completion of the first stage is a major sign of progress for the enormous south-north water diversion project, which cost an estimated 500 billion yuan (about 80 billion U.S. dollars) and is the largest of its kind in the world.

It will supply 9.5 billion cubic meters of water per year to the northern regions, including the cities of Beijing and Tianjin, and provinces of Henan and Hebei.

DOUBTS

However, arriving in Beijing is not enough. The water supplied through the project needs to stand the test of time.

A web user named "Ma Ke'an", a self-proclaimed doctor in physics, published an article online claiming China's south-to-north diversion project a failure, sparking debate.

Ma said the average flow rate and carrying capacity of the project failed to meet the design objective, which means the project cannot supply 9.5 billion cubic meters of water per year to the northern regions.

He also said river sand will eventually destroy the middle route of the water project. Water from Danjiangkou Reservoir contains large amounts of sand, but the designers insisted on discharging it directly into the main canal.

The main canal of the middle route is 1,432 km in length, featuring a 1,196.36-km-long open channel. Ma Ke'an said the water may freeze en route and fail to arrive in Beijing.

In response to these doubts, Xinhua interviewed Wang Hao, an academician with the Chinese Academy of Engineering and a famous water expert.

Ma's calculation is based on the motion trail of rubber duck with GPS and camera, which was put into the water in central China's Henan Province by an engineer.

The method was "unreliable" with an "unscientific conclusion", Wang told Xinhua. "Based on official calculations, the normal water flow rate should be one to 1.5 meters per second."

In addition, 9.5 billion cubic meters of water is an average figure. During years with heavy rain, the middle route can supply more than 12 billion cubic meters of water, while in dry years it will provide less.

Moreover, Wang said the Yangtze River has a low sediment load with only one kilograms per cubic meter. Since 2006, China has invested more than 10 billion yuan to prevent and treat water pollution and conserve soil in Danjiangkou Reservoir and its upper reaches.

"So it is ridiculous to say water from the south will have much more sediment," he said.

Wang Hao admitted transporting water in winter is one of the important problems the project has been facing. But plans are in place to prevent freezing.

One plan is to increase the water capacity during the frozen period to ensure water can flow under the icy surface. Other plans include de-icing facilities used along the route.

According to the Beijing office of the South-to-North Water Diversion Project, the project will operate in winter despite freezing rivers in certain sections north of Anyang City in Henan.

The huge project has been widely hailed as an example that the Chinese people are capable to bettering their lives through hard efforts. But since the project was conceived, debate has not ceased.

Just like people worrying about the water quality, they also express concerns about pollution. Some say the scheme's success may damage the water cycle balance and have an adverse impact on local ecology.

Critics even say it will only temporarily quench the thirst in the north.

"Despite those doubts and criticism, time will tell the truth," Mao Wei said.