Chapter 19 Chapter 4 Dujiangyan, Sichuan

The Minjiang River originates at the southern foot of Minshan Mountain in Songpan County, Sichuan Province, at an altitude of more than 4,000 meters, and flows into the Yangtze River in Yibin, with a total length of about 735 kilometers.From the source to Guanxian as the upstream, through the steep mountains and deep valleys, the 340-kilometer water course has a drop of more than 3,000 meters, and the current is turbulent.From Guanxian County to Leshan, and from Leshan to Yibin, they are the middle and lower reaches of the Minjiang River. It meanders on the Chengdu Plain with a small slope, and the water flows slowly.

The western Sichuan area is a famous rainy area in my country, and people call it "Xishu Leaking Sky". .And because the rainfall here is relatively concentrated, nearly 50% of the annual rainfall is concentrated in June, July, and August. Therefore, during this period, the Minjiang River often has flood peaks.In Guan County, the peak of the flood is sometimes as high as 7000 cubic meters per second, which is about 15 times the average annual second flow of medium water. Because the flow of the flood peak of the Minjiang River is very large, and because it begins to enter the plain when it flows to Guanxian County, the flow rate suddenly changes from fast to slow, so the flood is very easy to flood here, turning many places in the Chengdu Plain into a flood country.Therefore, the people of western Sichuan have a very long history of calming down the Minjiang River floods.According to literature records, the earliest and large-scale Mining project was to dig a flood channel, which is "East is Tuo" in "Shangshu·Yugong".It divides the flood of the Minjiang River from Guanxian County to the east and flows into the Tuojiang River.In ancient times, this spillway was called Jiangtuo. "Yu Gong" was written in the Warring States Period. Therefore, there should be no problem with this flood distribution channel in the Warring States Period.However, "Yu Gong" described it as the achievements of Dayu, which is not necessarily credible.The "Shu Wang Benji" written by the Han people and the "Huayang Guozhi" written by the Jin people Changzhu [qu Qu] both recorded this project as "destroying the jade mountain to eliminate water damage", and believed that it was completed under the enlightened leadership of the Prime Minister of Shu. .The "Shui Jing Zhu" written in the Northern Dynasties also said, "The water of the Jiang (Minjiang River) is different from the east, and it is also dug by the enlightened."Kaiming was born in the late Spring and Autumn Period. He presided over the decision of Yulei Mountain to make the east of the Minjiang River different from Tuo, which is closer to the truth.

Yulei Mountain, called Jianshan Mountain in ancient times, is located in the east of Minjiang River and west of Guanxian County.The so-called Jue Yulei Mountain is to open a gap in Yulei Mountain and become the water inlet of the Minjiang River flowing eastward into the spillway.It was later Baopingkou, one of the three canal head projects of Dujiang Water Conservancy.Today, the mouth of the treasure bottle is 20 meters wide, 40 meters high and 80 meters long.Of course, such a large-scale project was not achieved overnight, but the result of successive generations of processing and long-term water and sand erosion.But many people believe that its embryonic form should be laid by enlightenment.On the other hand, Baopingkou is also a water control mouth. Since both sides of the bank are stone walls, they are very strong, and no amount of flood can wash it away, so the performance of water control is good.According to contemporary measurements, even if the peak of the Minjiang River in Guanxian County is as high as 5,000 cubic meters per second, the water inflow at Baopingkou is still around 500 cubic meters per second, which will not cause floods in the Chengdu Plain.The spillway from Baopingkou to Jintang is about 100 kilometers long. Generally speaking, its upstream is equivalent to today's Baitiao River, and its downstream is the Pi (pipi) River.Since Jintang is about 300 meters lower than Guanxian County, the gradient of Jiangtuo is relatively large, and the flood flow is smooth and the flood diversion effect is good.

Enlightenment was originally the prime minister of King Wangdi (Du Yu) of Shu. Because of his meritorious service in water control, the people of Shu "got the land" and avoided being fish and turtles. Soon, he succeeded Du Yu as king and called Emperor Cong.In 316 BC, when the Twelfth Kaiming reigned, Shu was destroyed by Qin generals Zhang Yi and Sima Cuo.

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