To the west, above the lake, the setting sun colors half of the sky and the lake's surface hues of orange and gold while, opposite it, the pale moon rises gradually, shading the trees along the riverbank silver.

It is a picture-postcard moment and one that is being enjoyed once more this Mid-Autumn Festival after being absent for 30 years.

Wanping Lake, which is alongside Yongding River, had been dry for almost three decades before it was brought back to life a week ago.

During the upcoming National Day holiday, another dry lake next to the watercourse, Mencheng Lake, will also be refilled as part of an ambitious environmental project by the local government aimed at making Yongding River flow once more.

Mencheng Lake will be the third lake next to the Yongding River to be resuscitated since 2008.

"Six lakes along the course are in the refill plan, connected by streams," said Deng Zhuozhi, chief designer of the project.

He was speaking during the 2010 Yongding River Forum on Monday, organized by Beijing Water Association.

"The total area of the project will be 680 hectares when it is completed in 2014," he said.

Yongding River, which spans 170 km within Beijing, used to be the biggest to flow through the capital and has a history dating back 3 million years.

Zhang Minqiu, an engineer with the Beijing Institute of Water, said the river has been almost completely dry since 1992 and the ecosystems that depend on it have been seriously damaged.

The local government plans to invest 16.9 billion yuan on restoring the river's ecosystems, starting with refilling the lakes that feed it with reclaimed water from five sewage treatment plants in Beijing.

"The biggest difficulty is not the source of the water, but how to stop it from sinking so quickly into the ground, since Beijing is so thirsty that the underground water table is decreasing every year," said Deng.

His team uses geomembranes to solve the problem. The membranes are about 0.6 cm thick and can slow the leeching out of the lake water.

"We don't want the water to stop draining off completely. To be honest, that would be very hard to achieve. We are just trying to make it stay in the lake a bit longer," Deng said.

He is confident that the team, which has experience in restoring water systems in Beijng, including in the Olympic Green, will be able to achieve this.

"When the river is completely restored, it will help cool the city down, reduce the amount of dust and sand generated within Beijing by 20 percent and block sandstorms from Inner Mongolia."

Zhang, who is also a designer in Deng's team, said all the participants are under huge pressure but they are relishing the opportunity because few engineers get the chance to take part in such a large project connected to such a major waterway.

"Our plan is being challenged," Zhang said. "Some people say it's nature's choice to dry the river and we should not interfere."

Deng said others have complained that the river's ecosystems are not being restored as much as they are being created anew.

"Whatever it is, it's a good thing for the river and the people living there," he said. "The complainers should have seen the dust-cloud sweeping along the dry river."

China Daily

(China Daily 09/28/2010)