Dujiangyan is an irrigation infra-structure built in 256 BC during the Warring States Period of China by the Kingdom of Qin. It is located in the Min River in Sichuan Province, PR China, near the capital Chengdu. It is still in use today and still irrigates over 5,300 square kilometers of land in the region.

During the Warring States period, around 2,300 years ago, the people who lived along the banks of the Min River were plagued by annual flooding. Qin governor Li Bing investigated the problem and discovered that the river was swelled by the fast flowing spring melt-water from the local mountains that burst the banks when it reached the slow moving and heavily silted stretch below.

The most obvious solution would have been to build a dam but Li Bing had also been charged with keeping the waterway open for military vessels to supply troops on the frontier, so instead he preposed to construct an artificial levee to redirect a portion of the river's flow and then to cut a channel through Mount Yulei to discharge the excess water upon the dry Chengdu Plain beyond.

Li Bing received 100,000 taels of silver for the project from King Zhao of Qin and set to work with a team said to number tens of thousands. The levee was constructed from long sausage-shaped basket of woven bamboo filled with stones known as Zhulong held in place by wooden tripods known as Macha. The massive construction took four years to complete.

Cutting the channel proved to be a far greater problem as the tools available to him at the time, prior to the invention of gunpowder, were unable to penetrate the hard rock of the mountain so he used a combination of fire and water to heat and cool the rock until they cracked and could be removed. After eight years of work a 20 m wide channel had been gouged through the mountain.

After the system was finished, no more floods occurred. The irrigation made Sichuan the most productive agricultural place in China. Li Bing was loved so much that he became a god to the people there. On the east side of Dujiangyan, people built a shrine in remembrance of Li Bing.

Li Bings construction is also credited with giving the people of the region a laid-back attitude to life, by eliminating disaster and insuring a regular and bountiful harvest it has left them with plenty of free-time.

Today, Dujiangyan has become a major tourist attraction. It is also the admiration of scientists around the world, because it has one ingenious feature. Unlike contemporary dams where the water is blocked with a huge wall, Dujiangyan still lets water go through naturally. Modern dams do not let fish go through very well, since each dam is a wall and the water levels are different. In 2000, Dujiangyan became a UNESCO World Heritage Site.