Extended data
Water conservancy function
Dujiangyan project is mainly used for water diversion irrigation and flood control, and has the functions of water conveyance and urban water supply. It divides the water in the Minjiang River into two parts, one of which leads to the east side of Leiyu Mountain, so that the southern half of Chengdu Plain is no longer troubled by floods, while the northern half is free from drought. For thousands of years, the Minjiang River has turned harm into profit here, benefiting agriculture and mulberry, and turned Chengdu Plain into a "land of abundance" where people depend on floods and droughts and there is no famine, which further promoted the political, economic and cultural development of the whole Sichuan region.
At the beginning of Dujiangyan, shipping was the main thing, supplemented by irrigation. "Historical Records of the River Canal Book" records that "in the middle of Chengdu, this canal can be used for boats, which is more than enough for irrigation and immersion, and the people benefit from it." Because of this, the Minjiang River and the Yangtze River can be navigable, and the timber rich in the upper reaches of the Minjiang River can also be transported to Chengdu, making Chengdu the transportation center of Sichuan since the Qin Dynasty.
In addition to the benefits of water transportation, Dujiangyan's benefits in agricultural irrigation are also increasingly relied on by the world with the development of irrigation canal system. The water on the left bank of Minjiang River flows from Baokou, east of Lei Yu, and then flows to Chengdu along two main canals dug by Li Bing. In the Western Han Dynasty, Wen Weng, the prefect of Shu County, opened a new main canal to bring the Minjiang River water to the east of Chengdu Plain.
In the Eastern Han Dynasty, "Wang Chuanyuan" was "cut through 20 Li", which extended the irrigation canal to the highland of Shuangliu Mumashan. At the same time, the diversion canal on the right bank of Minjiang River extends to the southwest of Chengdu Plain on the basis of the Yang Mo opened in the Li Bing era. After hundreds of years of development, by the Han Dynasty, Dujiangyan irrigation area had developed from Pixian county in the Qin Dynasty to Chengdu, to Pengxian county, Guanghan and Xindu, with an irrigation area of "more than 10,000 hectares" (1 hectare in the Han Dynasty, about 70 mu today).
Geography of Hanshu refers to the Chengdu Plain, saying that "people eat rice and fish, and they don't worry about the years and customs." In the Tang Dynasty, Yizhou Cishi Stone spent a lot of money on digging canals. Since then, after many renovations, the canal system in the irrigation area has become more and more dense, and the irrigation area has been expanding. Dujiangyan's role has since become farmland irrigation.
During the Song Dynasty, Dujiangyan irrigation area developed significantly. According to Wang Anshi's "Epitaph of Liu Jun in JD.COM Prison", the irrigation area had reached at least 1 fu, 2 armies and 2 states * * * 1 2 counties, of which only Lu Guang was responsible for the irrigation area of 1.7 million hectares (about 1.377 million mu today). In Qing dynasty, the irrigation area reached 14 county, about 3 million mu.
By the Republic of China 1937 (in the 27th year of the Republic of China), the irrigation area was 26,375,438+0,000 mu; Summary of Dujiangyan Water Conservancy published by 1938 (twenty-seven years of the Republic of China) describes that the fields benefiting from Du Jiang weir "cover western Sichuan 14 counties ... about 5.2 million mu".
Since the establishment of People's Republic of China (PRC), the irrigation system in Dujiangyan has been continuously expanded and reformed. At the end of 1960, the irrigated area reached 6.78 million mu; By the early 1960s, the irrigation area had expanded to the east of Longquan Mountain, and nearly 300 reservoirs had been built, with an irrigation area of 8.58 million mu. Since then, the further transformation of the irrigation area has expanded the irrigation area to more than 654.38+million mu, with a total water diversion of 654.38+0 billion cubic meters, making it the largest irrigation project in the world at present.
Baidu encyclopedia-Dujiangyan