Water flow in the inner canal, the "heart" of the irrigation system, was successfully blocked at 10:50 a.m. on Wednesday, forcing the current to turn and run into the system's outer canal.

The renovation project, due to be completed in 42 days, would focus on dredging silt deposited in the inner canal, and aimed to let the ancient water conservation scheme operate for another 2,000 years, said Peng Shuming, director of the Dujiangyan Administrative Bureau.

The Dujiangyan scheme, some 50 km from Chengdu, capital of Sichuan Province, is said to be the world's oldest irrigation project still operating, supplying water to more than 670,000 hectares of farmland at present.

Built on the upper reaches of the Minjiang River, a major tributary of China's longest river, the Yangtze, Dujiangyan also provides water for daily and industrial use for people and enterprises in 50 big and medium-sized cities in Sichuan Province. 　　

Dujiangyan was included on the World Heritage List of the United Nations Educational, Scientific and Cultural Organization in 2000.

The current renovation project will also examine, repair and update irrigation facilities along the inner canal. Computers will be introduced to control and measure water flow, according to Peng.

To protect the ancient scheme from damage and pollution by modern machinery during the renovation, traditional methods were being used like putting tripods made from several logs bound together, and earth and stone-filled bamboo cages into the water to dam the flow.

Ancient architecture expert Zhong Tiankang said the greatness of the scheme rested on its important role in irrigating local farmland for more than 2,250 years and the fact it was still operating. He attributed this to conservation practices and maintenance by China's central authorities both in the past and at present.

Since the scheme was built in 256 B.C., it has undergone annual dredging and maintenance, a rule established by its builder Li Bing, an official of the Qin Kingdom during the Warring States period (475 B.C-221 B.C.).

Due to fewer floods on the Minjiang River, better water quality and less silt washed into the water control project area over the past decade, Dujiangyan had been not repaired since 1992, said Zhong.

Local tourism sources said tourists could see the whole process of renovating the ancient irrigation scheme, which has become a famous tourist attraction in Sichuan.

Wang Xueping, an official with the Dujiangyan Scenic Zone Administration, said the number of tourists to the zone had risen by 30 percent since October on a yearly basis, many of whom came to see the "real look" of the ancient scheme and how it was renovated.

(Xinhua News Agency November 13,2002)