A computerized device to monitor water levels was successfully installed Thursday in the inlet of Dujiangyan, the world's oldest irrigation works still in operation in China.

The 1-cubic-meter device was placed on a buoy and its movement as the water level changed would be recorded by sensors and relayed to a computer in the monitoring center on the bank, said Peng Shuming, head of the project administration.

Dujiangyan was built in BC 256 in southwest China's Sichuan Province along the upper reaches of the Minjiang River, a major branch of the Yangtze River. The scheme irrigates about 672,700 hectares of farmland and provides water for industrial and household use in 50 large and medium-sized cities.

The level in the inlet of Dujiangyan determined how much water was released for irrigation, said Li Junzhu, a local water conservation expert.

Experts believed that in ancient times residents marked water levels on rocks on the banks and marks made in the Qing Dynasty (1616-1911) were found on Dec.6, Li said.

The use of a computer would improve the efficiency and accuracy of the project, he added.

The river was blocked from Nov.13 to Wednesday for maintenance of the irrigation works at a cost to the government of 30 million yuan (US$3.62 million).

Dujiangyan and nearby Mt Qingcheng were listed as World Heritage sites in 2000 by the United Nations' Educational, Scientific and Cultural Organization (UNESCO).

(Xinhua News Agency December 27, 2002)