Time and subject of Dujiangyan construction

I hope it will help you: Dujiangyan Water Conservancy Project was built by Li Bing, the prefect of Shu County in Qin State, and his sons around 256 years ago. Up to now, it is the oldest and only grand water conservancy project in the world, which is characterized by not building a dam to divert water. Dujiangyan got its name from a weir built by Li Bing, the prefect of Shu County in the early Qin Dynasty. This is because Lei Yu, next to Dujiangyan, was called "Yan" before Qin and Han Dynasties. During the Shu and Han Dynasties in the Three Kingdoms, Du 'an County was established in Dujiangyan, which was named "Du 'an Weir". At the same time, it is also called "golden dike", which highlights the water diversion function of fish mouth and uses dike instead of weir as its name. In the Tang Dynasty, Dujiangyan was renamed "Jueweiyan". Because the materials and methods of embankment construction at that time were mainly "broken bamboo as a cage, with a diameter of three feet, filled with solid stone, which was called" open tail ". It was not until the Song Dynasty that Dujiangyan was mentioned for the first time in the history of the Song Dynasty: "Yongkang army ruled Dujiangyan at the age of 20, and the cage stone snake broke the river and stopped water to irrigate several counties' fields. Regarding the origin of this name, Shu Shui Kao said: "Fuhe River has two sources, namely Lijiang River and Liujiang River. "Liu Jiang is another name for Jian Jiang. On the Chengdu Plain, the Fuhe River is Yongjiang River and the Nanhe River is Jianjiang River. Their upper reaches are Baitiao River and Zouma River, which are divided into Dujiangyan and Neijiang. " Kuozhi said: "Du Jiang is the river of Chengdu". Since the Song Dynasty, the whole Dujiangyan water conservancy system project has been generally called Dujiangyan, which accurately represents the whole water conservancy system and has been used ever since. Chengdu Plain, now known as "Land of Abundance", was a place with serious floods and droughts in ancient times. The lamentation and tragic situation of "until two rulers crowded past in the foggy age of this area" and "man or fish became a turtle" in Li Bai's Shu Dao Nan is a true portrayal of that era. This situation is caused by the "bad" natural conditions in Minjiang River and Chengdu Plain. Minjiang River is the main tributary of the upper reaches of the Yangtze River, and the western Sichuan Basin through which it flows is a rainy area in China. Originated in 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 without a dam in Songpan. It flows southward through Songpan County, Dujiangyan City and Leshan City in Sichuan Province and joins the Yangtze River in Yibin City. The total length is 793 kilometers, and the drainage area is133,500 square kilometers. The average slope is 4.83‰, and the annual total water consumption is about 6543.8+0.5 billion m3. Minjiang River originates from Gonggangling and Langjialing of Minshan Mountain, with a total length of 735 kilometers and a drainage area of 6,543,800 square kilometers. The drop of the whole river is 3560 meters, and the hydraulic resources130,000 kilowatts or more. Minjiang River is a tributary with the largest amount of water in the upper reaches of the Yangtze River, and Dujiangyan is the upper reaches, mainly for driftwood and hydropower generation. Dujiangyan City to Leshan is the middle reaches, flowing through Chengdu Plain, and forms Dujiangyan Irrigation District together with Tuojiang River system and numerous artificial river networks. Below Leshan is the downstream, mainly shipping. There are more than 90 tributaries in Minjiang River, with Heishui River and Zagunao River in the upper reaches. Dujiangyan irrigation area in the middle reaches includes Heishi River, Jinma River, Jiang 'an River, Zouma River, Baitiao River and Puyang River. There are Qingyi River, Dadu River, mabian river and Yuexi River downstream. The main water source comes from the steep right bank of the mountain, and the major tributaries all overflow from the gap of the mountain on the right bank. Rainfall is mainly concentrated in the rainy season, so the water level of Minjiang River fluctuates rapidly and the water potential is turbulent. The Minjiang River flows southward from the west side of Chengdu Plain, which is an authentic river hanging on the ground for the whole Chengdu Plain, which is very interesting. The overall topography of Chengdu Plain is from Minjiang River to Leiyu Mountain, and it is inclined to the southeast with a great slope. Dujiangyan is 50 kilometers away from Chengdu, but the drop is 273 meters ... In ancient times, whenever the Minjiang River flooded, the Chengdu Plain was a Wang Yang. Once there is drought, it is thousands of miles away and there is no harvest. The flood of Minjiang River has long harmed Xichuan, devoured fertile land and infringed on people's livelihood, which has become a major obstacle to the survival and development of ancient Shu. The establishment of Dujiangyan has its specific historical roots. During the Warring States Period, people suffering from war longed for the early reunification of China. Coincidentally, after Shang Yang's political reform, Qin was once famous all over the world, virtuous and virtuous, and the country became stronger and stronger. They correctly realized the special strategic position of Bashu in the unification of China, and put forward that "if you get Shu, you will get Chu, and if Chu dies, the world will be merged" (Sima Cuo's words). Under this historical background, at the end of the Warring States Period, Zhao Haoqi of Qin appointed Li Bing, who was familiar with astronomy and geography and lived in seclusion, as the monarch of Shu. After Li Bing came to power, he first made up his mind to eradicate the flood in Minjiang River, develop agriculture in western Sichuan, benefit the Chengdu Plain and create an economic foundation for Qin to unify China. Construction process In the fifty-first year of the Qin Dynasty (256 BC), Li Bing and his son, the prefect of Shu County in Qin State, absorbed the experience of predecessors in water control and led the local people to build the world-famous Dujiangyan water conservancy project. Dujiangyan's master plan is to divide the Minjiang River into two branches, one of which is introduced into Chengdu Plain, which can not only divert floods and reduce disasters, but also divert water to irrigate farmland and turn harm into benefit. The main works include Yuzui diversion dike, Sha Fei weir spillway and Baojiangkou water intake. 1, the construction process of the bottle mouth First of all, Li Bing and his son invited many farmers with experience in water control, conducted on-the-spot investigation on the terrain and water regime, and decided to dig Leiyushan to divert water. Because gunpowder had not been invented at that time, Li Bing used flint to burst the rock, and finally cut a mountain pass with a width of 20 meters, a height of 40 meters and a length of 80 meters in Leiyushan. Because its shape resembles the bottle mouth, it is named "Treasure Bottle Mouth", and the stone pile separated from Leiyushan is called "Remaining Pile". The reason for repairing the bottle mouth is that only by opening Leiyushan and letting the water of Minjiang River flow eastward smoothly can the flow of the river in the west be reduced, so that the river in the west will no longer flood, and at the same time, the drought in the east can be alleviated, so that the surging river can flow into the arid area and irrigate the fertile fields there. This is the key link of flood control and the first step of Dujiangyan project. 2. The construction process of water diversion fishmouth After the completion of the water diversion project in Baokou, although it played the role of water diversion and irrigation, it was difficult for the river to flow into Baokou because of the high terrain east of the Yangtze River. In order to make the Minjiang River flow eastward smoothly and maintain a certain flow rate, and give full play to the flood diversion and irrigation function of Baokou, the builder libing decided to build a diversion weir on the Minjiang River to divide the river into two streams: one downstream and the other forcibly flowing into Baokou. Because the front end of the diversion weir looks like a fish head, it is called "fish mouth". The completion of the fish mouth divides the river flowing upstream into two parts: the west is called Waijiang, which flows down the Minjiang River in the rain; The east is called Neijiang, which flows into the bottle mouth. Because the Neijiang River is narrow and deep, and the outer river is wide and shallow, the water level is low in the dry season, and 60% of the river water flows into the Neijiang River with a low riverbed, which ensures the production and living water in Chengdu Plain. When the flood came, because of the high water level, most of the river water was discharged from the wide outer river. This design of automatic distribution of water inside and outside the river channel is called "four-six water diversion". 3. Construction of Sha Fei Weir In order to further control the amount of water flowing into Baokou, play the role of flood diversion and disaster reduction, and prevent the water in the irrigation area from fluctuating and becoming unstable, Li Bing also built a Hong Ping-dividing trough and a "Sha Fei Weir" spillway at the end of the Yuzui diversion dike near Baokou, so as to ensure that there is no disaster in Neijiang. There is a bend in front of the spillway, and the river forms a circulation. When the river exceeds the crest of the weir, it will flood. The flying sand weir is made of pebbles in bamboo cages, and the top of the weir is at a suitable height, which plays a role in regulating water quantity. When the water level in Neijiang is too high, the flood will overflow the flying sand weir and flow into the outer river through the flat sink, so that the water entering the bottle mouth will not be too large, and the Neijiang irrigation area will be protected from floods; At the same time, the aquatic products that crossed the Sha Fei weir and flowed into Waijiang created a swimming vortex. Due to centrifugation, mud and even boulders will be thrown over the Sha Fei weir, thus effectively reducing the sediment deposition around the bottle mouth. In order to observe and control the water quantity in Neijiang, Li Bing carved the portraits of three stone piles and put them into the water to determine the water level. Stone horses are also chiseled and placed in the middle of the river as a standard for scouring the beach when the water quantity is the least every year. Under the leadership of Li Bing, people overcame many difficulties, and after eight years of hard work, this historical project-Dujiangyan was finally built.