Dujiangyan
Ancient Qin irrigation system still in use today.
Dujiangyan is an ancient water management system located in Dujiangyan City, Sichuan, China. Built around 256 BC by the State of Qin to control floods and provide irrigation, it remains operational today. The system works along the Min River, a major tributary of the Yangtze, on the western edge of the Chengdu Plain, where the Sichuan Basin meets the Tibetan Plateau.
Before the project, the Min River surged down from the Min Mountains and slowed abruptly upon reaching the plain, dumping silt and causing frequent floods. King Zhao of Qin ordered the work, and instead of building a dam, engineers devised a method to channel and divide the river. This approach still irrigates over 5,300 square kilometers (2,000 square miles) of land, offering flood control, irrigation, water transport, and general water supply. After more than 2,250 years, it now waters 668,700 hectares of farmland. Along with the Zhengguo Canal in Shaanxi and the Lingqu Canal in Guangxi, it is known as one of the "three great hydraulic engineering projects of ancient China." In 2000, Dujiangyan was added to the UNESCO World Heritage List. It is also a State Priority Protected Site, among the first National Scenic Areas and Historical Sites, and a National ISO14000 Demonstration Area.
During the Warring States period, annual flooding plagued those living near the Min River. Qin hydrologist Li Bing studied the issue and found that fast spring meltwater from the mountains swelled the river, which then burst its banks when it hit the slow, silt-heavy lower stretch. A dam would have blocked military vessels needed to supply frontier troops, so instead, an artificial levee redirected part of the river, and a channel was cut through Mount Yulei to send excess water onto the dry Chengdu Plain.
King Zhao of Qin allocated 100,000 taels of silver and sent tens of thousands of workers. The levee was built using long, sausage-shaped bamboo baskets filled with stones, called Zhulong, held in place by wooden tripods known as Macha. The water-diversion levee, shaped like a fish's mouth, took four years to complete. Cutting the channel was harder; without gunpowder, hand tools would have taken decades. Li Bing used fire and water to rapidly heat and cool the rocks, cracking them for easier removal. After eight years, a channel 20 meters (66 feet) wide was carved through the mountain.
Once finished, the sys
- constructed
- c. 256 BC
- commissioned_by
- King Zhao of Qin
- field
- Hydraulic engineering
- location
- Dujiangyan City, Sichuan, China
- known_for
- Ancient irrigation and flood control system still in use
- world_heritage
- Inscribed in 2000
Lore & Background
During the Warring States period, people living near the Min River suffered annual flooding. Qin hydrologist Li Bing investigated and found that spring meltwater swelled the river, which then burst its banks when it reached the slow, silted lower stretch. Instead of building a dam, which would block military vessels, an artificial levee was constructed to redirect part of the river's flow, and a channel was cut through Mount Yulei to discharge excess water onto the dry Chengdu Plain. King Zhao of Qin allocated 100,000 taels of silver and sent tens of thousands of workers. The levee was built from woven bamboo baskets filled with stones, held by wooden tripods, and took four years to complete. Cutting the channel required eight years, using fire and water to crack the rocks before gunpowder was available. The original Dujiangyan irrigation system was damaged by the 1933 Diexi earthquake but was repaired and continued functioning. The Anlan Bridge is a notable historic structure, though it is not part of a widely recognized list of 'Five Ancient Bridges of China'.
Reader's Guide
The Dujiangyan irrigation system consists of three main constructions: the Yuzui or Fish Mouth Levee, which divides water into inner and outer streams; the Feishayan or Flying Sand Weir, a 200-meter opening that drains excess water and silt; and the Baopingkou or Bottle-Neck Channel, which distributes water to farmlands. The system irrigates over 5,300 km² of land and has provided comprehensive benefits in flood control, irrigation, water transport, and general water consumption for over 2,250 years. It is one of the 'three great hydraulic engineering projects of the Qin,' along with the Zhengguo Canal and the Lingqu Canal. After completion, no more floods occurred, and Sichuan became a highly productive agricultural region. The system was damaged by the 1933 Diexi earthquake and rebuilt by Zhang Yuan and his sons. It became a UNESCO World Heritage Site in 2000 and is now a major tourist attraction.
Did You Know?
- The Dujiangyan system uses a method of channeling and dividing water rather than damming it.
- The Yuzui Levee is named for its conical head that resembles the mouth of a fish.
- The original Dujiangyan irrigation system was destroyed by the 1933 Diexi earthquake.
- The Anlan or Couple's Bridge is known as one of the Five Ancient Bridges of China.
Frequently Asked Questions
What is Dujiangyan?
Dujiangyan is an ancient hydraulic engineering complex in Dujiangyan City, Sichuan, built to tame the Min River's seasonal floods while irrigating the Chengdu Plain. It has been continuously operational for roughly 2,270 years, making it one of the longest-running water-management projects on record.
Who commissioned Dujiangyan and why?
King Zhao of Qin ordered the construction around 256 BC because the Min River would surge down from the Min Mountains, lose speed on the plain, and deposit silt that triggered repeated devastating floods. Instead of a conventional dam, the Qin engineers designed a gravity-fed diversion and channel system that still functions today.
How does the Dujiangyan system work without any pumps or gates?
A fish-mouth diversion structure splits the river's flow, and a series of weirs and channels use gravity and the river's natural gradient to route excess water around the plain during high season while feeding a steady irrigation supply during dry months. The entire mechanism relies on topography and flow dynamics rather than any mechanical components.
Why is Dujiangyan considered so important?
It demonstrates that a well-designed hydraulic system can outlast the empires that built it, having sustained agriculture across the Chengdu Plain for over two millennia without being decommissioned. Its continuous operation and engineering ingenuity earned it recognition as a global cultural and scientific landmark.
When was Dujiangyan inscribed as a UNESCO World Heritage Site?
UNESCO added Dujiangyan to the World Heritage List in 2000, citing it as an outstanding example of ancient hydraulic engineering that remains fully in use. The inscription acknowledged its unique flood-control and irrigation approach, which predates most comparable systems by centuries.
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