Dujiangyan scenic spot

Dujiangyan is a world cultural heritage site (listed as "world cultural heritage" by UNESCO in 2000), a world natural heritage site (Sichuan Giant Panda Habitat), a national key cultural relics protection unit, a national scenic spot and a national AAAAA tourist attraction. Dujiangyan is located in the west of Dujiangyan City, Chengdu City, Sichuan Province. It is located on the Minjiang River in the west of Chengdu Plain. It was built in the last year of King Zhao of Qin Dynasty (about 256-251 BC). It is a large-scale water conservancy project organized by Li Bing and his son, the governor of Shu County, on the basis of the previous bieling excavation. It is composed of water diversion fish mouth, Feisha weir, baopingkou and other parts. It has been playing a role in flood control and irrigation for more than 2000 years Chengdu Plain has become a "land of abundance" characterized by water and drought. Up to now, the irrigated area has reached more than 30 counties and cities, covering an area of nearly 10 million mu. It is the world's oldest, only remaining, still in use, and characterized by water diversion without dam. It embodies the hard work, courage and wisdom of the ancient Chinese working people. Dujiangyan scenic area mainly includes Fulong temple, Erwang temple, Anlan Suoqiao, yuleiguan, Lidui Park, yuleishan Park, yunvfeng, Lingyan temple, Puzhao temple, Cuiyue lake, Dujiangyan water conservancy project, etc. On August 13, 2018, the 69th International Executive Council of the international irrigation and drainage Commission, held in Saskatoon, Canada, announced the world irrigation project heritage list in 2018 (the fifth batch). Among them, China's Dujiangyan and other four projects were all successfully declared.

Location context

Dujiangyan is located in the west of Dujiangyan City (formerly Guanxian county), Chengdu City, Sichuan Province. It is located on the Minjiang River in the west of Chengdu Plain, about 50 km away from Chengdu City and 20 km away from Qingcheng Mountain scenic spot.

Climatic characteristics

Dujiangyan city belongs to the subtropical monsoon humid climate zone, with an average annual temperature of 15.2 ℃, an average annual precipitation of nearly 1200 mm, and an average annual frost free period of 280 days. There are four distinct seasons here. There is no intense heat in summer. The average temperature in July and August is about 24 ℃, and the average maximum temperature is only 28 ℃. There is no severe cold in winter. The average temperature in the coldest January is 4.6 ℃, and the average minimum temperature is about 1 ℃.

The origin of the name

At the beginning of the construction of Dujiangyan by Li Bing, the prefect of Qin Shu County, Dujiangyan was named "Jianpeng". This is because Yulei mountain beside Dujiangyan was called "Jianshan" before Qin and Han Dynasties. At that time, Diqiang people lived around Dujiangyan. They called it "Peng", so Dujiangyan was called "Jianpeng".

During the Shuhan period of the Three Kingdoms, Dujiangyan was set up as Du'an County, which was named "Du'an Weir". At the same time, it is also called "Jindi", which highlights the function of Yuzui water diversion dike and uses dike instead of weir as its name.

In the Tang Dynasty, Dujiangyan was renamed "Fuwei Weir". Because at that time, the materials and methods used to build the embankment were mainly "broken bamboo as a cage, with a diameter of three feet, and filled with stones, so as to accumulate and backwater", that is, to use bamboo cages to load stones, which is called "tail".

It was not until the Song Dynasty that Dujiangyan was mentioned for the first time in the history of the Song Dynasty: "the Yongkang army ruled Dujiangyan at the age of one year, and the cage stone snake conquered the river to suppress the water, so as to irrigate several prefectures and fields."

As for the origin of the name Dujiang, "SHUSHUI Kao" said: "Fu River, a Chengdu river, has two sources, namely Pi River and Liujiang River." Liujiang is another name for Jianjiang. The Fu River in Chengdu Plain is Pi River, and the Nan River is Jianjiang River. The upper reaches of them are Baitiao River and zouma River, which are separated by the rivers in Dujiangyan. "Kuodizhi" said: "Dujiang river is Chengdu river.". Since the Song Dynasty, the whole Dujiangyan water conservancy system project was summarized as Dujiangyan, which accurately represents the whole water conservancy system and has been used up to now.

Construction background

Chengdu Plain, known as "land of abundance", was a place with serious flood and drought disasters in ancient times. Li Bai's exclamations and tragedies in the famous poem "difficult road to Shu" are the true portrayal of that era. This situation is caused by the "bad" natural conditions in the Minjiang River and Chengdu Plain.

Minjiang River is a major tributary of the upper reaches of the Yangtze River. The Western Sichuan Basin is a rainy area in China. It originates from the southern foot of Minshan Mountain at the junction of Sichuan and Gansu. It is divided into East source and West source. The East source comes from gonggangling and the West source comes from langjialing. The two sources meet in Zhangla, Songpan. It flows southward through Songpan County, Dujiangyan City and Leshan City in Sichuan Province, and joins the Yangtze River in Yibin City. It has a total length of 793 kilometers and a drainage area of 133.500 square kilometers. The average slope is 4.83%, and the annual total water volume is about 15 billion m3. The drop of the whole river is 3560m, and the water resources are more than 13 million kilowatts.

Minjiang River is one of the largest tributaries in the upper reaches of the Yangtze River. Above Dujiangyan, it is the upper reaches, mainly for driftwood and hydropower generation. The section from Dujiangyan City to Leshan is the middle reaches, which flows through Chengdu plain area, and forms Dujiangyan irrigation area together with Tuojiang River system and many artificial river networks. Below Leshan, it is the lower reaches, mainly for shipping. There are more than 90 tributaries in Minjiang River, including Heishui River and Zagunao River in the upper reaches, Heishi River, Jinma River, Jiang'an River, Zouma River, Baitiao River and Puyang River in Dujiangyan Irrigation Area in the middle reaches, and Qingyi River, Dadu River, Mabian River and Yuexi River in the lower reaches. The main source of water comes from the steep Right Bank of the mountain. Most of the tributaries overflow from the mountain gap on the right bank. The rainfall is mainly concentrated in the rainy season, so the water of Minjiang River fluctuates rapidly and the water potential is turbulent.

Minjiang River flows southward from the west side of Chengdu Plain out of Minshan Mountain range. It is a real river hanging above the ground to the whole Chengdu Plain, and it is very suspended. The whole terrain of Chengdu Plain inclines southeast from Yulei mountain at the exit of Minjiang River. Dujiangyan is 50km away from Chengdu with a drop of 273m. In ancient times, when the Minjiang River was flooded, the Chengdu Plain was a vast ocean; when there was a drought, the land was bare and there was no harvest. The flood of Minjiang River affected Xichuan for a long time, engulfed fertile land and disturbed people's livelihood, which became a major obstacle to the survival and development of ancient Shu state.

The foundation of Dujiangyan has its specific historical origin. During the Warring States period, there were many wars. The people who suffered from the war were eager for the reunification of China as soon as possible. Coincidentally, after the reform of Shang Yang's political system, the state of Qin was in great numbers, and its power was growing. They correctly recognized the special strategic position of Ba and Shu in the process of unifying China, "if you get Shu, you will get Chu, and if Chu dies, you will have the world united" (SIMA Cuo, Prime Minister of Qin Dynasty). In this historical context, at the end of the Warring States period, King Zhao appointed Li Bing, who knew astronomy, geography and lived in seclusion in min'e, as the prefect of Shu county. After taking office, Li Bing first made up his mind to eradicate the flood of Minjiang River, develop agriculture in Western Sichuan, benefit Chengdu Plain, and create economic foundation for Qin to unify China.

Building environment

Dujiangyan is located in the place where Minjiang River flows from valley to alluvial plain. It irrigates ten thousand hectares of farmland on Chengdu plain to the east of Guanxian county. It turns out that the upper reaches of the Minjiang River flow through the steep mountains. As soon as it reaches the Chengdu Plain, the water speed suddenly slows down, so a large amount of sediment and rocks are deposited and the river channel is silted up.

Every year, when the rainy season comes, the water potential of Minjiang River and other tributaries rises sharply, often flooding; when there is not enough rain, it will cause drought. Two or three hundred years before the completion of Dujiangyan, King Du Yu of the ancient Shu Kingdom opened an artificial river at the exit of the Minjiang River to divide the Minjiang River into the Tuojiang River to eliminate water disasters.

In the 51st year of emperor Zhaoxiang of Qin Dynasty (256 BC), Li Bing was the governor of Shu. Li Bing built Dujiangyan on the basis of previous flood control and relying on the local people in Guanxian, where the Minjiang River flows out of the mountains and into the plain.

Construction process

In the 51st year of emperor Zhaoxiang of Qin Dynasty (256 BC), Li Bing, the governor of Shu County of Qin state, and his son learned from the experience of predecessors in water control and led the local people to preside over the construction of the famous Dujiangyan water conservancy project. The overall planning of Dujiangyan is to divide the Minjiang River into two streams, one of which is introduced into Chengdu Plain, which can not only divert flood and reduce disaster, but also divert water to irrigate farmland and turn harm into benefit. The main works include Yuzui breakwater, Feisha weir spillway and baopingkou intake.

1. The construction process of baopingkou

First of all, Li Bing and his son invited many farmers with experience in water control to make field investigation on the terrain and water regime, and determined to dig through Yulei mountain to divert water. Because gunpowder had not been invented at that time, Li Bing used fire to burn stone and burst the rock. Finally, he chiseled a 20 meter wide, 40 meter high and 80 meter long pass in Yulei mountain. Because its shape is similar to the mouth of a bottle, it is named "baopingkou", and the stone pile separated from Yulei mountain is called "Lidui".

The reason why baopingkou is to be built is that only when Yulei mountain is opened up and the Minjiang River can flow smoothly to the East can the flow of the river in the west be reduced and the river in the west be no longer flooded. At the same time, the drought in the East can be relieved and the surging river can flow into the arid area and irrigate the good farmland there. This is the key link of flood control and the first step of Dujiangyan project.

2. Construction process of water diversion fish mouth

After the completion of baopingkou water diversion project, although it played the role of diversion and irrigation, it was difficult for the river water to flow into baopingkou due to the high terrain in the east of the river. In order to make the Minjiang River flow East smoothly and maintain a certain flow, and give full play to the flood diversion and irrigation function of baopingkou, the builder Li Bing decided to build a water diversion weir in the Minjiang River after digging baopingkou Branch: one goes down the river, the other is forced to flow into baopingkou. Because the front end of the weir is shaped like the head of a fish, it is called "fish mouth".

The construction of Yuzui divides the upstream river into two parts: the west is called Waijiang River, which flows downstream along the Minjiang River; the East is called Neijiang River, which flows into baopingkou. Because the inner river is narrow and deep, the outer river is wide and shallow, so the water is low

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