Dujiangyan

Synopsis

Dujiangyan is located in Chengdu, Sichuan Province. It is a large-scale water conservancy project built in 256 BC under the direction of Li Bing and his son, who were governors of the Shu Commandery of the Qin State during the Warring States period, with a history of over 2,200 years. It is the oldest and still operational large-scale water conservancy project in the world. In 2000, it was listed as a UNESCO World Heritage Site and is hailed as the originator of global water conservancy culture.

Overview

The Dujiangyan Irrigation System is located in Dujiangyan City, Chengdu, Sichuan Province, China. It is one of the greatest hydraulic engineering projects of ancient China. Constructed around 256 BC under the direction of Li Bing, the governor of Shu Commandery of the Qin state during the Warring States period, and his son, it has a history of over 2,200 years. Dujiangyan is the world's oldest and only surviving grand-scale hydraulic project characterized by its dam-free water diversion system. It remains fully functional for irrigation and flood control to this day, irrigating an area exceeding 10 million mu (approximately 667,000 hectares). In 2000, Dujiangyan was inscribed on the UNESCO World Heritage List.

The completion of Dujiangyan transformed the Chengdu Plain from a wilderness plagued by frequent floods and droughts into the "Land of Abundance" (Tianfu Zhi Guo), where water regulation was at human command, and famine was unknown. This magnificent project embodies the extraordinary wisdom and creativity of the ancient Chinese working people. Its scientific principles and practical utility continue to amaze modern hydraulic engineers.

Engineering Principles

The core principle of Dujiangyan is to utilize the natural topography and water flow patterns to achieve water diversion, sediment discharge, and flow control of the Minjiang River through three main components, all without constructing any dam.

The Yuzui (Fish Mouth) Levee is named for its resemblance to a fish's mouth. It splits the Minjiang River into two: the Outer River, the main course primarily for flood discharge, and the Inner River, which diverts water for irrigating the Chengdu Plain. During the dry season, the Inner River receives 60% of the water to ensure irrigation, while during the flood season, the Outer River receives 60% to discharge floodwaters—this is the wisdom of the "40-60 split."

Feishayan (Flying Sand Weir) is a spillway that diverts sediment and excess water from the Inner River back to the Outer River. Li Bing ingeniously utilized the centrifugal force generated by the curved water flow to automatically sling sediment towards the Outer River. It is estimated that Feishayan can discharge about 90% of the sediment from the Inner River, a marvel of ancient hydraulic engineering.

Baopingkou (Precious Bottle Neck) is a man-made water intake channel, approximately 20 meters wide, cut through the rock of Mount Yulei. Li Bing employed the "fire and water" method—first heating the rock with fire and then dousing it with cold water to cause it to crack—taking eight years to complete. Shaped like a bottle neck, Baopingkou effectively controls the volume of water entering the Chengdu Plain.

Historical Value

The construction of Dujiangyan completely altered the fate of the Chengdu Plain. Before its existence, the Minjiang River, upon exiting the mountains, would suddenly slow down, causing sediment deposition and frequent flooding or droughts. Through their meticulously designed dam-less hydraulic system, Li Bing and his son achieved automatic water diversion, sediment discharge, and flow control, turning the Chengdu Plain into the "Land of Abundance" secure against both floods and droughts.

For over two millennia, Dujiangyan has undergone repairs and maintenance through successive dynasties. The six-character maxim left by Li Bing, "Deepen the channel, keep the weir low" (深淘滩，低作堰), remains the core principle for its maintenance to this day. The annual Water Releasing Festival held during the Qingming season is one of the most important local folk activities, commemorating the achievements of Li Bing and his son.

Tourist Information

The Dujiangyan Scenic Area is quite extensive. The main attractions include the three major hydraulic components—Yuzui, Feishayan, and Baopingkou—as well as the Anlan Suspension Bridge, the Two Kings Temple (Erwang Miao), and Fulongguan Temple. The Anlan Suspension Bridge spans the Minjiang River, offering a close-up view of its mighty flow. The Two Kings Temple was built to commemorate Li Bing and his son and houses a collection of historical water management documents.

Dujiangyan is adjacent to Mount Qingcheng, and both are UNESCO World Heritage Sites, often visited on the same itinerary. It is about a one-hour drive from downtown Chengdu.

References

1. UNESCO World Heritage Centre: https://whc.unesco.org/en/list/1001
2. Baidu Baike: https://baike.baidu.com/item/都江堰
3. Wikipedia: https://zh.wikipedia.org/zh-cn/都江堰