There has been great progress in people's awareness in preserving the water resources in Sanjiangyuan. After years of a herding ban and large-scale relocation of herdsmen, things are looking better in the Sanjiangyuan nature reserve more vegetation, and in some major lakes, the water level has gradually risen.

But it's not that simple. Many people have warned that the rising water level could be the result of melting glaciers rather than the restoration of grassland. And they've found there are more creeks drying up. An accurate assessment requires more scientific research.

The same is true for intervention measures which could have negative unintended consequences. For example, moving herdsmen out of the grassland could bring back the grass. But without livestock to graze, grass quality suffers. In at least one case, rats moved in. And poisoning the rats would kill the eagles which prey on them.

Nature has its own circles or cycles for sustainable growth. Man and nature are not enemies. Experts say humans must find ways to cohabit with nature in a harmonious manner. Nature is a complex system, or even systems. To change one thing is to change everything.

Sanjiangyuan is called the water tower, but it's not only the water source for China, but for Asia and the world. Many I have interviewed say that diversion and hydropower projects will inevitably alter the eco-system.

If we put economic development first, we will pay for it in the future. In tomorrow's episode, we profile a dedicated water ranger, a Tibetan environmentalist, whose dream is to build Sanjiangyuan into a paradise ranch with man and nature in harmony.

(Editor:Mirenda Wu)