Analysis of information sources in references of the Wikipedia article "Dujiangyan" in English language version.
Li Bing was commissioned to conduct an extensive hydraulic survey to regulate the unpredictable course of the swiftly flowing spring-thaw waters of the Min River that regularly flooded areas and settlements on the plains around Chengdu, and simultaneously ensure that the Min River flowed unimpeded through Chengdu, facilitating navigation by military vessels that could service Qin's logistical supply lines.
By 270 BCE he had drawn up plans to mitigate the Min River's floodwaters for year-round irrigation on the Chengdu Plain and navigability to Chengdu. The original plan called for the construction of weirs or levees to harness the Min River at Dujiangyan, where the hills meet the Chengdu Plain, and of a diversion channel to irrigate the plain that would cut straight through the natural barrier posed by Mount Jian.
In 268 BCE, Li Bing is said to have personally led ten of thousands of workers in the initial stage of construction on the Min River banks. The workers made bamboo cages and threw cages of rocks into the middle of the river. It took them four years to complete a water-diversion levee resembling a fish's mouth. When the water reaches Yuzu, the 'fish's mouth,' it is naturally diverted into the inner and outer flows. The inner flow is the diversion channel that leads to Chengdu.
Prior to the invention of gunpowder, manual labourers using only drill rods and stone hammers would have taken 30 years to cut through the mountain. Qin military planners required more immediate results, so Li Bing proposed using the expeditious and simple technology of using controlled blazes to scorch the rocks and then dousing them with cold water. The seemingly limitless forest resources of the region at that time – evidence of which is provided by the Shu kingdom period tree trunk coffins recently unearthed in downtown Chengdu – made such an option possible. King Zhao of Qin allocated 100,000 taels of silver for the project.
It took a further eight years to cut through the mountain, and the 20-meter (66 ft)-wide culvert allows the water to flow into the Chengdu Plain. The key part of the project was the diversion gate called Baopingkou that resembles the neck of a bottle, and through this passage, the waters of the Min River could irrigate the Chengdu Plain in perpetuity. In 256 BCE, after 14 years of arduous labor, the Dujiangyan project was completed. That at least is one received historical account, but it is undeniable that for more than two millennia this irrigation project has been in use on the Chengdu Plain.
[Luo Xinben, a professor at Southwest University for Nationalities] and other scholars say Chengdu's laid-back culture was spawned by its 2-millennium-old irrigation system.
[Tan Jihe, a researcher at the Sichuan Provincial Academy of Social Sciences] says Du Jiang Yan, and Chengdu's fertile soil and moist air, made it easy to plant rice, corn, potatoes and a rich assortment of citrus and other fruits, giving farmers not only good harvests but also plenty of time for leisure.
More than 2,000 years ago, Li Bing (c.250-200 BC) served as a local governor of Shu State. At that time, the Mingjiang River flowed quickly down from the mountains. As it ran across the Chengdu Plain, it frequently flooded the Chengdu agricultural area where local farmers suffered much from the water disaster. Li Bing and his son designed this water control system and organized thousands of local people to construct the project.
The Fish Mouth Water-Dividing Dam is built in the middle of the river. It is the main part of Dujiangyan Irrigation system. The Fish mouth functions to divide the river into an inner canal and an outer canal. Long ago, when Li Ping worked as the local governor of the Shu State, he found the old river canal was too narrow to hold much water, which often overflowed the banks and caused disastrous floods. Based on natural geographic conditions, Li Bing organized the people to build a man-made dam. The whole dam looks like a fish, and the front dam has a circular cone shaped like a fish mouth.
It is the dam that diverts water into the outer canal and the inner canal. The inner water canal functions as the main stream for irrigation purposes; the outer river is mainly used to drain excessive water and sand. During flood seasons the inner canal holds 40 percent of the water in the river, and 60 percent of the water flows into the outer river. It is vice versa in dry seasons. About 80 percent of the silt is carried away along the outer river.
The water flows along the inner canal towards the Bottle-Neck Channel. On the way it passes the Flying Sand Fence, which has a 200-meter (660 ft)-wide opening from south to north. The Fence joins the inner and outer canals. The fence functions to control the flow of water and discharge excess into the outer canal from the inner canal.
During the dry seasons the fence doesn't work much, but when floods occur, the river rushes forward along the inner canal. As it approaches the fence, the river begins to turn fast, and soon many whirlpools are formed. The whirlpools change quickly, swee-ping away sand and pebbles, and throwing them into the outer canal. During the flood seasons, this spillway transports 80 percent of the sediments into the outer river, and at the same time excessive water flows over the Flying Sands Fence into the outer river. In ancient times, there was no cement in use. Instead, huge bamboo cages were used as the fence. They were filled with stones and pebbles. However, at present, a reinforced concrete weir has replaced the ancient fence.
The inner canal leads to the Bottleneck Channel, which is the entrance of the extensive irrigation system. A trunk canal cuts the mountain into two parts. The small part was later called Li Dui, which means an isolated hill. Chengdu looks like a large bottle, and the trunk canal between the mountain and the hill takes the shape of a bottleneck. During the flood seasons, the water will not overflow into the trunk canal. Instead, it flows in whirlpools into the outer canal. The trunk canal works as a check gate to safeguard the Chengdu Plain.
Anlan Suspension Bridge is one of the five ancient bridges in China. The total length is 320 m. Its ancient name was called the Rope Suspension Bridge or the Bamboo and Cane Suspension Bridge. Unfortunately, a fire caused by war towards the end of the Ming dynasty destroyed the original bridge. In 1803, a new bridge was built. It was made with local bamboo rope chains, and the bridge bottom floor was replaced with wooden plates. The old bridge lasted until the 1970s when it was replaced by a steel chains bridge.
Erwang (Two King's) Temple was built to commemorate Li Bing and his son. Erwang means two kings. Originally, the temple was called Wangdi Temple in memory of Duyu, the king of the ancient Shu. Later Wangdi Temple was relocated in Pixian county during the Southern and Northern Dynasties. Local people renamed the temple Chongdemiao to express respect for Li Bing and his son. Chongde means worship of virtue or reverence. During the Song dynasty the temple was called Wangmiao, which means the king's temple. Down to the Qing dynasty it was called Erwang Temple. People offered Li Bing and his son the posthumous title of Wang (king).
The temple complex occupies an area of 10,072 square meters. the ancient timber buildings remain similar in design and style to other ancient Chinese architecture. The broad roof, perfect decoration, strict size and traditional use of color meet in harmony with the mountaintop environment. However, the temple buildings are not placed based on the concept of the north-south axis.
The main hall is devoted to Li Bing himself. The statue is newly molded. The old statue was a larger-than-life painted statue, and the figure looked like a wise scholar looking at the rushing river below. The newly molded figure has a silk map in his hand, and appears to be thinking about the blueprint of the project.
According to Folk tale, July 24 of the Chinese Lunar Calendar is Li Ping's birthday. On that day many local people visit the temple where they prostrate themselves before the image of Li Ping and his son and burn incense to honor them. At the same time, the beatings of drums and gongs resound to the sky as incense smoke curls upwards.
Li Bing's hall is a compound. The hall faces an opera stage across the courtyard below, surrounded by other buildings. On July 24 of the Chinese Lunar Calendar during the Ming and Qing dynasties entertainers performed local operas on the stage. People gathered in the courtyard to watch the performance. Legend says the actors offered the performance mainly for Li Bing, as tribute for his great contribution to local people.
The rear hall is devoted to Li Bing's son. His son's statue is newly molded. The figure stands firmly with a tool in his hands as ready to level mountains. Behind the statue is the Minjiang River, which serves as the background. Li Bing's son had a name called Erlang.
Erlang is a popular legendary figure in Chinese folk literature. In the folk stories, he has a close relationship with Li Bing. It should be pointed out that no recorded historical evidence could be found to show Erlang was Li Bing's son. In Chinese feudal society, it was a great problem for a family to have no offspring, so local people regarded Erlang as Li Bing's son. They sincerely wished Li Bing would have a son so that Li's family tree would continue.
There is a delicate pavilion called Guanlantin. Carved characters are on both sides of stonewalls. These are quotations of how to manage the Dujiangyan Irrigation System. One of the famous inscriptions engraved on the wall is an eight-character quotation from Li Ping. It says: When the river flows in zigzags, cut a straight channel; when the riverbed is wide and shallow, dig it deeper.
The Dragon-Taming Temple is located in Lidui Park, which is close to the city. It was built in the 3rd century. Originally, it was devoted to Fan Changsheng, the founder of Tianshi Dao, one Daoist sect in the Jin dynasty (266–420). During the Five Dynasties and Ten States, Li Bing was conferred the posthumous title called Da'anwang, and his hall was set up here in honor of him. A popular legend during the Song dynasty was that Erwang, Li Bing's son, had subdued an evil dragon here. So the temple was renamed as the Dragon-Taming Temple accordingly.
In 1974, a stone statue of Li Bing was unearthed from the river base. Now it is placed in the middle of the main hall. It is 2.9 m in height and 4.5 tons in weight. Based on archeological studies, the statue was carved in 168 during the East Han Dynasty.
Li Bing was commissioned to conduct an extensive hydraulic survey to regulate the unpredictable course of the swiftly flowing spring-thaw waters of the Min River that regularly flooded areas and settlements on the plains around Chengdu, and simultaneously ensure that the Min River flowed unimpeded through Chengdu, facilitating navigation by military vessels that could service Qin's logistical supply lines.
By 270 BCE he had drawn up plans to mitigate the Min River's floodwaters for year-round irrigation on the Chengdu Plain and navigability to Chengdu. The original plan called for the construction of weirs or levees to harness the Min River at Dujiangyan, where the hills meet the Chengdu Plain, and of a diversion channel to irrigate the plain that would cut straight through the natural barrier posed by Mount Jian.
In 268 BCE, Li Bing is said to have personally led ten of thousands of workers in the initial stage of construction on the Min River banks. The workers made bamboo cages and threw cages of rocks into the middle of the river. It took them four years to complete a water-diversion levee resembling a fish's mouth. When the water reaches Yuzu, the 'fish's mouth,' it is naturally diverted into the inner and outer flows. The inner flow is the diversion channel that leads to Chengdu.
Prior to the invention of gunpowder, manual labourers using only drill rods and stone hammers would have taken 30 years to cut through the mountain. Qin military planners required more immediate results, so Li Bing proposed using the expeditious and simple technology of using controlled blazes to scorch the rocks and then dousing them with cold water. The seemingly limitless forest resources of the region at that time – evidence of which is provided by the Shu kingdom period tree trunk coffins recently unearthed in downtown Chengdu – made such an option possible. King Zhao of Qin allocated 100,000 taels of silver for the project.
It took a further eight years to cut through the mountain, and the 20-meter (66 ft)-wide culvert allows the water to flow into the Chengdu Plain. The key part of the project was the diversion gate called Baopingkou that resembles the neck of a bottle, and through this passage, the waters of the Min River could irrigate the Chengdu Plain in perpetuity. In 256 BCE, after 14 years of arduous labor, the Dujiangyan project was completed. That at least is one received historical account, but it is undeniable that for more than two millennia this irrigation project has been in use on the Chengdu Plain.
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