Chapter 20 Section 2 Li Bing built the Dujiang Water Conservancy

The main purpose of enlightened water control is to relieve the water damage of the Minjiang River.The main purpose of Li Bing's water control is to develop the water conservancy of the Minjiang River, that is, to use the water of the Minjiang River to develop agriculture and shipping in the Chengdu Plain. The Chengdu Plain is located among four mountains, Longquan Mountain in the east, Emei Mountain in the south, Qionglai Mountain in the west and Min Mountain in the north.The width from northwest to southeast is about 40-70 kilometers, the length from northeast to southwest is about 180 kilometers, and the area is more than 8,000 square kilometers.Formed by the alluvial deposits of the Minjiang River and the Tuojiang River, the alluvium is thick and rich in organic matter and minerals.The terrain is higher in the northwest and lower in the southeast, with a slope of about 3‰ to 6‰.The climate here is warm, with abundant rainfall, the average annual temperature is 15°C-17.5°C, the frost-free period is as long as 270-340 days, and the average annual rainfall is about 1000 mm.These conditions are very conducive to the development of agriculture.However, there are also unfavorable factors in the Chengdu Plain, especially the seasonal distribution of rainfall is not coordinated with the growth of crops.Less rain in spring affects spring sowing; late summer rain is unfavorable to crop development; heavy rain in midsummer often causes floods.In addition, except for the Minjiang River, most of the natural waterways are short and inconvenient for shipping.

Many of the above data are measured by modern scientific methods. Of course, it was impossible for Li Bing to grasp such details back then.But he is familiar with astronomy, geography, and water veins, and he is very familiar with the advantages and disadvantages of the natural conditions of the Chengdu Plain.Therefore, during the six years he served as the prefect of Shu County, that is, the fifty-first year and fifty-sixth year of King Qin Zhao (256-251 BC), he organized the local people of all ethnic groups to vigorously build the Dujiang water conservancy to make full use of the water conservancy here. favorable conditions and overcome unfavorable conditions.The main engineering projects at that time were: blocking the [Yongyong] River as a gate, piercing the Pi [Pipi] River, checking the River, digging away from the pile, and burning the soldiers.

Shu people call weirs Hou.Blocking up the river is to build a large weir on the Minjiang River in order to block part of the Minjiang River to the east of Jianshan (Yulei Mountain) and develop irrigation and shipping in the Chengdu Plain.It should be said that the structure of the weir was relatively simple, but ingenious.It makes full use of the sandbar in the center of the Minjiang River. On the one hand, the top of the sandbar is transformed into a fish mouth shape to facilitate water diversion; Aquarius mouth.In this way, the Minjiang River was divided into the Neijiang River and the Waijiang River. The east side of Yuzui and Shazhou was called the Neijiang River, and the west side was called the Waijiang River.

"Shui Jing Zhu Jiang Shui Zhu" said that Li Bing not only built Dujiangyan, but also summed up the valuable experience of making weirs.This is what was later called "scouring the beach deep and making weirs low".Deep scouring the beach refers to scouring Neijiang to a deeper level.Because the Chengdu Plain is relatively dry in spring and early summer, it is also the dry season of the Minjiang River. Only by digging the Neijiang River deeper can more water from the Minjiang River flow into the Chengdu Plain.In midsummer, the Chengdu Plain is rainy, and it is also the flood season of the Minjiang River. Only low-level weirs can make the excess flood water flowing into the inner river flow into the outer river, so as to avoid flooding in the Chengdu Plain (Figure 5).

"Huayang Guozhi · Shu Zhi" said that when Li Bing built the weir, he erected a stone figure in each of the three rivers (Minjiang, Waijiang, and Neijiang) in Baishayou (near the mouth of Baisha River), and engraved "Water is not enough, full No shoulders" nine characters.There is a stone man standing in the middle of the river, and Li Bing's intention is to suppress water.The engraved nine characters are also a request to Jiangshen. When he walks in the water, he should neither be too much, covering the stone man's shoulders, nor too little, below the stone man's feet.It is superstitious to use stone men to suppress water and ask the god of the river for water.But the nine characters also show people that the water level between the stone man's shoulders and feet is the safe water level of the Minjiang River, otherwise, preparations should be made for flood control or drought control.Scholars believe that this is the earliest recorded water gauge in my country. From 1974 to 1975, people dug up two stone figures in Waijiang, one of which was 290 cm tall and 96 cm wide at the shoulders.Although it is not Li Bing's original work, it was made by the water officials of the Eastern Han Dynasty, but Li Bing's stone figures, generally speaking, should be the same as it.

The Pijiang River and Jianjiang River that Li Bing crossed are two important canals in the Neijiang irrigation area.They all use the Minjiang River as their water source, in the east of Guanxian County, and divert water from Jiangtuo to the south.Due to the very brief records of the Erjiang River in the original documents, and because the descendants have repeatedly adjusted the Erjiang River waterway, there are different opinions in the academic circles about the routes of the Pi and Jianjing.Based on the later literature, generally speaking, the upper reaches of the Pijiang River are equivalent to today's Baitiao River, and the lower reaches are the Fuhe River; the upper reaches of the Jianjiang River are equivalent to today's Zouma River, and the lower reaches are the Jinjiang River.The two rivers meet in the south of Chengdu, continue to flow south, and return to the Minjiang River in Pengshan County.In addition to digging the Erjiang River, Li Bing also opened an irrigation channel to the west of the Minjiang River, the Yangmo River, which was the predecessor of the later Yangma River.

The drilling of the Erjiang River has greatly improved the shipping and irrigation conditions of the Chengdu Plain.Since then, millions of bamboos and woods produced in Minshan drifted down the Minjiang River, Neijiang River, Pi River and Jianjiang River every year, and entered the Chengdu Plain, providing abundant and cheap building materials for towns along the river.Passenger and cargo ships, like shuttles, travel to and from all over the plain.There are thousands of hectares of fields in the Erjiang River Basin. Since then, "floods and droughts follow people" here, "drought will divert water to infiltrate, and rain will stop water gates."This provides the necessary guarantee for the development of local agriculture.The construction of the Dujiang Water Conservancy Project has made the Chengdu Plain a "Land of Abundance".

The purpose of chiseling off the pile and burning the soldiers is to improve the waterway of the Minjiang River. "Historical Records Hequ Book" contains: "Shu Shoubing cuts away the stone (pile) to avoid the harm of foaming water."Gumoshui is today's Dadu River, therefore,.Binglan is today's Chiyan Mountain in the north of Yibin City, facing the Minjiang River.Because the rock is hard and difficult to cut, it is cracked by exciting water and fire, expanding with heat and contracting with cold.Lidui and Binglan both stand upright against the river, forming rapids and eddies, threatening the safety of ships, so Li Bing wanted to eradicate them.

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