Dujiangyan Water Conservancy Project consists of three main projects: Yuzui Fenshui Dike, Feishayan Spillway and Baojiangkou Water Intake, as well as auxiliary projects such as Baizhang Dike and herringbone Dike. Scientifically solved the problems of automatic river diversion, automatic sediment discharge and inflow control, eliminated floods, and made the western Sichuan plain a "land of abundance" with people following floods and droughts. For more than two thousand years, it has been playing the role of flood control and irrigation. By the end of 1998, the irrigated area of Dujiangyan has reached more than 40 counties, with an irrigated area of 668,700 hectares.
Yu Zui is a diversion dam built in the middle of the river, which divides the turbulent Minjiang River into an outer river and an inner river. Flood discharge from the outer river and irrigation from the inner river. The flying sand weir plays the role of flood discharge and sediment discharge and water transfer. Treasure bottle mouth controls water inflow, because the mouth looks like a bottleneck, it is called treasure bottle mouth. The inland river flows into the irrigated farmland in the western Sichuan plain through the bottle mouth. The part of the mountain cut from Leiyu Mountain is called "leaving a heap".
Dujiangyan Water Conservancy Project makes full use of the local geographical conditions of high northwest and low southeast, and according to the special topography, water veins and water potential of the river outlet, it takes advantage of the situation, does not build a dam to take water, and irrigates by gravity, so as to achieve the interdependence of dike, water diversion, flood discharge, sediment discharge and flow control, and give full play to the comprehensive benefits of flood control, irrigation, water delivery and social water use. After the completion of Dujiangyan, Chengdu Plain is fertile for thousands of miles. "Floods and droughts come from people, and there is no famine, so it is called abundance." Sichuan's economy and culture have made great progress. Its biggest point is that the weir has been built for more than two thousand years, and it is playing an increasingly important role. The establishment of Dujiangyan is based on the premise of not destroying natural resources and making full use of natural resources to serve mankind, turning harm into benefit, and making people, land and water highly coordinated and unified.
Dujiangyan project still exists today, and it is still in operation. With the development of science and technology and the expansion of irrigation area, since 1936, concrete mortar pebble technology has been gradually used to repair and strengthen the canal head, and some water conservancy facilities have been added. The project layout of the ancient weir and the water control strategies such as "deep scouring beach, low weir", "guiding according to the situation, adapting to the time", "cutting corners when encountering the bay, and pumping heart when encountering the right" have not changed, and Dujiangyan water conservancy has not changed either. After carefully watching the design of the whole project, water conservancy experts were amazed at its high scientific level. For example, the design of flying sand weir is a good use of swirl theory. This kind of weir can divert water for irrigation at ordinary times, and it can be discharged into the outer river during flood. It also has the function of discharging sand and gravel, and sometimes very large stones can be rolled out of the weir. At that time, there was no cement, so such a large project used local materials and used pebbles in bamboo cages as weirs, which saved costs and achieved remarkable results.
Dujiangyan has beautiful scenery and many places of interest, and it is also an ideal tourist destination. Dujiangyan area has Erwang Temple, Fulongguan, An Lan Suoqiao and other places of interest.
Erwang Temple is located on the hillside on the right bank of Minjiang River, in front of Dujiangyan. Originally a memorial hall for the King of Shu, it was renamed "Chongde Hall" because Qi Jianwu (AD 494-498) offered sacrifices to Li Bing and his son. After the Song Dynasty (AD 960 ~ 1279), Li Bing and his son were successively crowned as kings by the emperor, so people later called it the "Two Kings Temple". The main hall of the temple is dedicated to the statue of Li Bing and his son, and there are famous sayings about water control and inscriptions by poets.
Fulongguan is located in Lidui Park. Legend has it that Li Bing descended the dragon here when he was controlling the water. There are three existing halls, and the front hall has a statue of Li Bingshi in the Eastern Han Dynasty (AD 25-220). There are also the ruins of the Eastern Han Dynasty weir stone tripod, and the scene when the sages and princesses in the Tang Dynasty became monks in Qingcheng Mountain.
An Lan Lock Bridge is also called "An Lan Bridge" and "Lovers Bridge". It was built before the Song Dynasty. Located above the fish mouth of Dujiangyan, it is known as the "five ancient bridges in China" and is the most distinctive landscape of Dujiangyan. The cable bridge is supported by wooden rafts and stone piers, suspended by thick bamboo cables, paved with wooden boards and surrounded by bamboo cables on both sides, with a total length of about 500 meters. In the late Ming dynasty (17th century), it was destroyed by war. The present bridge is a steel cable concrete pile.
Dujiangyan is not only a world-famous ancient water conservancy project in China, but also a famous scenic spot. 1982, Dujiangyan, as an important part of Qingchengshan-Dujiangyan scenic spot in Sichuan, was approved by the State Council to be included in the first batch of national scenic spots. On May 8, 2007, Chengdu Qingchengshan-Dujiangyan Scenic Spot was officially approved by the National Tourism Administration as a national 5A-level scenic spot.
According to the definition of cultural heritage in the second paragraph of Article 1 of the United Nations Convention for the Protection of the World Cultural and Natural Heritage: "Architecture: a single or connected architectural group with outstanding universal value in terms of architectural style, uniform distribution or combination with environmental scenery from a historical, artistic or scientific point of view". Dujiangyan water conservancy project has a long history, huge scale, reasonable layout, scientific operation and harmonious combination with the environment, which has outstanding historical and scientific universal value. Dujiangyan was identified as a world cultural heritage at the 24th session of the United Nations World Heritage Committee in 2000.