Dujiangyan Waterworks: A heritage that barely escaped

Before the earthquake

A small city in Sichuan province - Dujiangyan - has caught the world's attention with Premier Wen Jiabao directing relief efforts from here in the wake of the devastating earthquake. It is also one of the rare survivors in the catastrophe that most of the parts of the ancient hydraulic wonder have been found intact.

According to the local cultural relics bureau, only the front gate at the Dujiangyan scenic region was damaged in this week's quake. But sadly, Erwangmiao - Temple of Two Kings - where people paid tribute to Li Bing and his son for 2,000 years near Dujiangyan city, is said to have totally collapsed after Monday's quake.

"Dujiangyan was built according to the natural flow of the river. I think it is not prone to damage. I'm rather sure of that," Luo Zhewen, director of China Cultural Relics Society who has visited Sichuan many times, told local media.

To the Chinese, Dujiangyan is a source of much pride, and was designated a World Cultural Heritage site in 2000.

In 256 BC, Li Bing, chief of the Shu Prefecture (roughly today's Sichuan) of the Qin Dukedom in the Warring States Period (475-221 BC), led the local people in building a massive water conservancy project that curbed floods and irrigated farmlands.

Known as Dujiangyan, the project has remained functional for the past 2,200 years and has irrigated some 670,000 hectares of fields by 1998. It is vital for turning the Sichuan Basin into one of the country's major grain producing areas.

Minjiang, a major tributary of the Yangtze River, originates from the northern mountains of Sichuan. Every spring and summer, heavy rains wash mud and rocks into the narrow river. Unlike the Nile River that brings fertile sand to the banks every year, Minjiang ravages the area with its annual floods, washing away farmlands.

According to legend, Li Bing and his son, who had strong enough magical powers to curb a vicious dragon, invited local farmers to study the geographical conditions before deciding a tunnel should be dug through a mountain to divert water for irrigation.

They burnt rocks until they exploded and finally managed to dig a tunnel 20 m wide, 40 m high and 80 m long through the Yulei Hill. The tunnel is named Baopingkou (Treasure Bottle Mouth) after its peculiar shape.

To direct water into the "bottleneck," a weir was built upstream. Pebble-filled bamboo cages were placed in the river, forming a narrow islet resembling a fish mouth. The surging river is thus divided into two: The inner part flows toward the "bottle" and irrigates farmlands; the outer part continues its journey south to meet the Yangtze River.