Li Bing built the Dujiangyan Irrigation System-李冰修建都江


Li Bing was a water conservancy expert during the Warring States period, and due to his expertise in flood control, he became a revered figure akin to a water deity in the eyes of the people. One of Li Bing’s most famous achievements in flood control was the construction of the Dujiangyan Irrigation System.

At that time, the Qin Dynasty had conquered the state of Shu, turning it into the Shu Commandery of the Qin Dynasty. The Shu Commandery was located on a plain, rich in grain production, with the Min River flowing through it, making it a vital source of military provisions for the Qin army during their campaigns. In 280 BC, Qin General Sima Cuo led an army to invade the state of Chu via the Min River. However, at Shangyu in Chu, the army faced difficulties in obtaining supplies, hampering their progress. This was because all the military resources were located in Chengdu, and the provisions needed to be transported from Chengdu to the Min River dock via land routes. The inconvenient transportation made it difficult for the army to replenish its provisions in a timely manner, thus affecting its combat effectiveness. Sima Cuo then came up with an idea: to change the course of the Min River so that it flowed through Chengdu.

In 272 BC, King Zhao of Qin appointed Li Bing as the governor of the Shu Commandery, and the task of altering the course of the Min River fell upon him. Li Bing spent over three years studying the water conditions of the Min River, aiming to devise a comprehensive plan that could safely divert the river into Chengdu while preventing the risk of flooding. In 270 BC, he finally formulated a complete water control scheme: to divert the water of the Min River into Chengdu, it was necessary to construct a hydraulic project that could both divert water and prevent flooding.

The Min River, the largest tributary of the Yangtze River, rushed down from the snowy mountains with a swift current, and during dry years, it would run dry, while in flood years, it would overflow. The key to Li Bing’s flood control efforts lay in selecting the right location for the hydraulic project, which would determine the success or failure of the entire endeavor. After conducting extensive on-site surveys, Li Bing ultimately chose the critical point between the mountainous terrain and the plain. This location served as the throat of the Min River, effectively controlling its flow.

With the plan in place, Li Bing began to recruit laborers and initiate construction.

However, a seemingly insurmountable problem arose: to divert the Min River into Chengdu, it had to pass through a sharp mountain called Yulei Mountain. Yulei Mountain blocked the eastern route of the river, so it had to be cut through to allow the river to enter Chengdu. With no other option, Li Bing decided to carve through the mountain.

Carving through the mountain was no easy task. At that time, there was no gunpowder, so blasting the rock with explosives was not possible. Instead, the laborers had to use hammers to chip away at the rock, a painstaking process. However, to split a large mountain like this using manual labor would take at least thirty years, and the Qin Dynasty could not afford to wait that long before launching an attack on Chu. Therefore, Li Bing came up with a solution: he first chiseled a deep groove in the rock and then filled it with a large amount of firewood. After igniting the wood, the rock would heat up and expand, and when cold river water was poured onto the hot rock, it would contract, causing the rock to crack and split. The laborers would then climb onto the rocks and continue chiseling. This significantly accelerated the progress of the project. Eight years later, Li Bing finally led the laborers to open up a gap twenty meters wide, forty meters high, and eighty meters long. This gap, resembling the mouth of a bottle, was named “Bao Ping Kou” (Treasure Bottle Mouth), and the pile of rocks chiseled out of it was called “Li Dui” (Leaving Pile).

The reason Li Bing wanted to create such an opening to divert the Min River to the east was not only to change its course to Chengdu but also to reduce the flow of water to the west. By diverting the water to the east, Li Bing aimed to decrease the volume of water in the western route. This was the focal point of the flood control efforts.

Once this step was completed, Li Bing began to divert the water of the Min River into “Bao Ping Kou.” It took another four years for the laborers to fill bamboo baskets with cobblestones and transport them to the middle of the river with ferries, where they were then thrown into the river. As the cobblestones accumulated, they divided the Min River into two parts. This created two branches of the Min River: the inner river, which was redirected into Chengdu through “Bao Ping Kou,” and the outer river, which followed the original course of the Min River. The stone-constructed diversion dam, exposed on the outside of the Min River, looked like the mouth of a large fish from a distance and was named “Fen Shui Yu Zhou” (Fish Mouth Diversion).

With the Min River divided into two, the inner river was narrow and deep, while the outer river was wide and shallow. During the dry season, most of the river water would flow into the inner riverbed, ensuring that Chengdu would not suffer from water shortages and droughts. During periods of high water volume, the excess water would flow into the wider outer river. This design automatically regulated the water level of the two rivers, preventing both droughts and floods.

To further ensure the balance of water flow in the two rivers, Li Bing built an overflow channel, “Fei Sha Yan” (Flying Sand Weir), between “Fen Shui Yu Zhou” and “Bao Ping Kou.” Constructed using bamboo baskets filled with cobblestones, it served as a lower dam. When the water in the inner river exceeded the capacity of “Bao Ping Kou,” the excess water would spill over “Fei Sha Yan” and flow into the outer river, ensuring that Chengdu Plain would not be threatened by flooding. Additionally, “Fei Sha Yan” had another function – it could redirect sediment carried by the Min River downstream. As the river water flowed down from the snowy mountains, it brought along sand and stones. Without proper management, this sediment could block “Bao Ping Kou.” With “Fei Sha Yan” in place, when the water flowed down, it would create a whirlpool here, and the sediment in the water would be thrown into the outer river.

With these three procedures – “Bao Ping Kou,” “Fen Shui Yu Zhou,” and “Fei Sha Yan” – Li Bing finally completed the construction of the Dujiangyan Irrigation System in 256 BC after fourteen years of effort. To ensure the continued operation of Dujiangyan, Li Bing also established a maintenance system. When he built Dujiangyan, Li Bing buried a stone horse in the riverbed of the inner river diverted by “Bao Ping Kou,” marking the position where the riverbed should be cleared of silt every year during the dry season. Additionally, “Fei Sha Yan’s” height needed to be adjusted annually to ensure it could both divert water and handle floods. Li Bing’s maintenance system remains in use to this day.

After the completion of Dujiangyan, the water from the inner river of the Min River irrigated the Chengdu Plain, and the people began digging channels of various sizes to use the river water for irrigation. Chengdu became a prosperous land within the Shu Commandery. Initially, King of Qin ordered Li Bing to build Dujiangyan to aid in the attack on Chu by supplying provisions for the Qin army. However, unintentionally, it brought benefits to the local people. In commemoration of Li Bing and his son’s assistance, the people built the Erwang Temple at the head of Dujiangyan. Every Qingming Festival, they would come to the temple to pay their respects. After the annual maintenance work was completed, a water release ceremony would also be held at the temple – Li Bing became a divine figure in the hearts of the people in the Dujiangyan irrigation area.