1. What made Dujiangyan?
Today, Dujiangyan City, 50 kilometers away from Chengdu, Sichuan, stands the world-famous Dujiangyan water conservancy project. Every year in Tomb-Sweeping Day, local people hold a grand celebration here. People pray around Dujiangyan, hoping that the weather will be fine in the coming year. The god people worship is Li Bing, the famous Shu county magistrate in China.
Li Bing statue at the entrance of Dujiangyan scenic spot
The reason why Li Bing changed from an ordinary person to a god is entirely because he built Dujiangyan in the upper reaches of Minjiang River. Dujiangyan has been playing the role of flood diversion and disaster reduction for more than 2000 years since its completion. The reason why Dujiangyan has risen is to start with the unification of Bashu by Qin.
That was in the 4th century BC, when the State of Qin surrounded Chu, Minister Sima Cuo suggested that only by occupying Shu first and taking advantage of its superiority in the upper reaches of the Yangtze River could Chu be defeated from the commanding heights.
The ancient Shu culture is an ancient civilization, which emerged at the historic moment from the Shang Dynasty, creating Sanxingdui culture and Jinsha culture. Controlling Shu is equivalent to controlling the whole Sichuan basin. Strategically speaking, Sichuan basin has become the outpost of Qin's destruction of Chu.
Warring States map
Therefore, King Hui of Qin quickly adopted Sima Cuo's suggestion of destroying Shu before attacking Chu. In 3 16 BC, the state of Qin went south from Jinniu Road, and sent troops to wipe out Shu without blowing off dust, successfully occupying the whole Chengdu Plain. In 280 BC, Qin Jun went to the Minjiang River and used the Yangtze River to transport troops to attack Chu. However, due to the problem of grain and grass, this plan was forced to run aground.
This war against Chu shows that Qin's strategy of attacking Chu with Shu as an outpost is flawed, because at that time, training and training were mainly in Guanghan and Chengdu, the center of Shu, but shipbuilding, grain transportation and grass transportation were all in the upper reaches of Minjiang River, and soldiers and ordnance had to walk at least 50 kilometers from Chengdu to Minjiang River, so it was difficult to replenish troops in combat.
Jinniu avenue
Later, when Li Bing was the prefect of Shu County, the king of Qin decided to divert the Minjiang River on a large scale to meet the needs of military water transportation.
Then how can we let the Minjiang River flow through Chengdu?
Li Bing finally decided to build a water conservancy project that can not only divert water but also prevent floods in the upper reaches of Minjiang River. Later, in order to support Li Bing, the King of Qin sent 654.38+10,000 troops (50,000) to help Li Bing build this water conservancy project.
2. How was Dujiangyan built?
In order to solve this problem, Li Bing finally decided to build Dujiangyan water conservancy project between the mountains where Longmen Mountain and Chengdu Plain meet today. People first make a movable cage out of bamboo, then put pebbles in the cage, and then the ferry throws stones into the river. Through several years' efforts, a dam similar to a fishmouth appeared between the Minjiang River, which divided the Minjiang River into two parts. The inland river was mainly used for irrigation and the outer river was mainly used for flood control and diversion. The inland river was introduced near the Chengdu Plain, which is the famous fishmouth in Dujiangyan today.
When Li Bing built Dujiangyan, in order to realize effective irrigation of Chengdu Plain, he diverted water from Minjiang River twice, and the first diversion was concentrated in Yukou. The function of the fish mouth is to divide water. After the Minjiang River left the mountain pass, the fish mouth in the river began to divert the river for the first time. The Minjiang River separated by the fish mouth is called Neijiang, and the Minjiang River outside the fish mouth is called Waijiang.
But the problem is that the Minjiang River, which originated between Gansu and Sichuan, is blocked by a big mountain! Minjiang River is an important tributary of the upper reaches of the Yangtze River. Due to the great difference in altitude, the Minjiang River is fast-flowing and prone to floods. Before Dujiangyan was built, the Minjiang River was more like a runaway wild horse, which was out of control. Especially today, Leiyushan in the northwest of Chengdu Plain is the only place that Neijiang passes through. The mountain blocks the eastward flow of Minjiang River, which often leads to drought in the east and floods in the west.
Therefore, to build Dujiangyan, we must find a way to get through the obstacle of Leiyushan. In the ancient society without modern machinery, how did the ancients start the mountain?
In fact, the ancients used the principle of thermal expansion and cold contraction. They first burned between stones with fire, then poured cold water on them, and finally cut mountains. It took Li Bing eight years to finally split a gap in Leiyushan, so that water could flow into Chengdu Plain smoothly. Is this famous? Bottle mouth? .
Li Bing chiseled through Lei Yu. Is this a manual chisel? Bottle mouth?
The appearance of the bottle mouth made the water from Minjiang River and Neijiang flow into Chengdu Plain continuously, and Dujiangyan, a world-famous water conservancy project, was declared completed.
There is a local proverb in Sichuan, namely? Dujiangyan first, then Tianfu country? The meaning is obvious, that is, before the construction of Dujiangyan, the floods in Chengdu Plain were continuous, but the construction of Dujiangyan made this once flooded Chengdu Plain known to people? Land of abundance? .