|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 60 percent of the water in the river, and 40 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.
At the Flying Sand Fence
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-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,.
At the Bottle-Neck Channel
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.
The trunk canal technically has two functions.
1. it distributes the water to irrigate the farming land in western Sichuan.
2. the trunk canal works together with the Flying-Sand Fence to keep the flow below a certain point in the inner canal during the flood seasons.
Some stone tablets stand on the isolated hill. They are engraved in Buddhist Sanskrit. The local people hope that the Buddhist tablets can influence the Buddhist to harness flood disasters. Actually, the three main projects have worked in harmony with one another for centuries. They form a complete and scientific irrigation and drainage network, which successfully ensures that there will be water in the Minjiang River for irrigation.
On the way to Fulonguan (The Dragon-Taming Temple)
The Dragon-Taming Temple is located in the beautiful Lidui Park, which is close to the city. It was built in the 3rd century. Originally, it was devoted to Fan Changsheng (范长生, the founder of Tianshi Dao(天师道), one Daoist sect ) in the Jin Dynasty (265-420). During the Five Dynasties and Ten States, Li Bing was conferred the posthumous title called Da’anwang (大安王), 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. The carved figure looks graceful. Now it is placed in the middle of the main hall. It is 2.9m in height and 4.5 tons in weight. Based on archeological studies, the statue was carved in 168 during the East Han Dynasty.