The creation of Dujiangyan has its specific historical roots. During the Warring States Period, swordsmen rose to prominence and wars broke out. The people who suffered from wars longed for the early reunification of China. Coincidentally, the Qin State, which had undergone Shang Yang's reforms, had many famous kings and virtuous ministers, and the country became increasingly prosperous. They correctly understood the special strategic position of Ba and Shu in the process of unifying China. "If you win Shu, you will win Chu. If Chu dies, the world will be united." (Qin Prime Minister Sima mistakenly said).

In this historical context, at the end of the Warring States Period, King Zhao of Qin appointed Li Bing, who knew astronomy and geography and lived in seclusion in Min'e, as the prefect of Shu County. After Li Bing took office, he first determined to eradicate the floods in the Minjiang River, develop agriculture in western Sichuan, benefit the Chengdu Plain, and create an economic foundation for the Qin State to unify China.

The Chengdu Plain, known as the "Land of Abundance", was a place prone to severe floods and droughts in ancient times. In the famous poem "The Road to Shu Is Difficult", Li Bai's laments and misery like "there are silkworms and fishtails, how confused the founding of the country is" and "people may become fish and turtles" are true portrayals of that era. This situation is caused by the "harsh" natural conditions of the Minjiang River and Chengdu Plain.

The Minjiang River has more than 90 large and small tributaries, including the Heishui River and Zagunao River in the upper reaches; the Heishi River, Jinma River, Jiang'an River, Zouma River, Baitiao River, Puyang River, etc. in the Dujiangyan Irrigation Area in the middle reaches; The lower reaches include Qingyi River, Dadu River, Mabian River, Yuexi River, etc. The main water source comes from the steep right bank of the mountain. The large tributaries overflow from the gaps in the mountains on the right bank. Rainfall is mainly concentrated in the rainy season, so the water of the Minjiang River rises and falls rapidly and the water is turbulent.

Extended information:

When the rainy season comes every year, the water in the Minjiang River and other tributaries rises sharply, often causing flooding; when there is insufficient rain, it will cause drought. Two or three hundred years before the completion of Dujiangyan, King Du Yu of the ancient Shu Kingdom, as a sign of enlightenment, opened an artificial river at the outlet of the Minjiang River, diverting the water from the Minjiang River and flowing into the Tuojiang River to eliminate water damage.

In the fifty-first year of King Qin Zhaoxiang (256 BC), Li Bing was the governor of Shu County. Based on the water control methods of his predecessors and relying on the local people, Li Bing built Dujiangyan in Guanxian County, where the Minjiang River flows out of the mountains and flows into the plains.

The overall plan of Dujiangyan is to divide the water flow of the Min River into two streams, one of which is introduced into the Chengdu Plain. This can not only divert floods and reduce disasters, but also divert water to irrigate fields and turn harm into benefit. The main project includes the Yuzui diversion dike, Feishayan spillway and Baopingkou water inlet.

Baidu Encyclopedia-Dujiangyan