Water started to flow along the central line of the country's south-north water diversion projects on Friday. After more than a decade of construction, the 1,432-kilometer canal will begin to transport more than 9.5 billion cubic meters of water each year from Danjiangkou reservoir to Beijing and other North China cities - the amount equals one-sixth of the flow of the Yellow River, China's second longest natural waterway.

This is one of the largest water diversion projects in history, with about 100 million people in the dry cities of Beijing and Tianjin and Henan and Hebei provinces benefiting from it. It is definitely a great project.

It is natural that such a mammoth project comes with debate. The biggest opposition focuses on the ecological impact the project might bring. There are also arguments about the fairness of "ensuring Beijing's water use by sacrificing other regions' needs. "

Generally speaking, all artificial constructions impose a certain degree of damage on the ecosystem. The key is whether the positive results are worth it.

In the south-north water diversion project, the positive effects overwhelm the negative ones. It will alleviate the water shortage pressures in North China, while the impact on Hanjiang river areas is within controllable range.

Hundreds of thousands of people in Hubei and Henan were relocated for the project. People in the north should be grateful for their sacrifice.

The successful completion of the first phase of the central water-diversion line shows that China has the capability to balance and coordinate various interests. The project is also a social project that tests the country capability.

Of course, this project is not just a matter for praises. It should also serve as a warning of China's embarrassing water resource situation.

North China is not that naturally short of water resources. The crisis is more a result of the population density and the heavy use of water for living and business uses.

We hope the water diversion is only to solve the emergency of the north's water shortage, not a signal that the north can still squander precious resources in its industrial and urban expansion. The north must be determined to establish higher water use efficiency.

China should not only solve the problems of the moment, but needs to look ahead.

The south-north water diversion may not be the most ideal solution for China's water crisis. But it is the most realistic option. The future assessment of its role lies in how much we try to maximize the positive effects and minimize the negative ones. The flow of water through the canal on Friday is not the end of the scheme, but a new start of a social project.