Chapter 30 Section 3 Expansion of Guanzhong Irrigation District in Tang Dynasty

From the end of the Eastern Han Dynasty to the Three Kingdoms, Jin and Southern and Northern Dynasties, due to the turbulent political situation, the farmland and water conservancy in Guanzhong either had no time to repair it, or were damaged by wars, generally speaking, it was in a state of decline.Among them, because of the management of Cao Wei and Western Wei, only Chengguoqu continued to develop. Guanzhong is the base of Cao Wei's war against Shu, and there are heavy troops stationed here. It started from the needs of military food and water transportation, and expanded the Chengguo Canal twice.For the first time, in the second year of Taihe (AD 228), Wei Zhen first extended the Chengguo Canal from Mei County to Baoji in the west, extending the canal for more than 100 miles.This section of the new canal uses Qianshui (Qianshui), the main tributary of the upper reaches of the Weishui River, as its water source.For the second time, in the first year of Qinglong (233 A.D.) of Emperor Wei Ming, under the auspices of Sima Yi, the Chengguo Canal was extended eastward for more than 100 miles, to the vicinity of Jingshui River entering Wei.Although the Western Wei Dynasty established the country in Guanzhong, Emperor Zuo was very short, only 22 years (535-556 AD), but in order to ensure the necessary food production, in the 13th year of Emperor Wen Datong (547 AD), Liumen Weir was built to the west of Wugong. , to collect some small water from the north of the Weihe River to supplement the water volume of the Chengguo Canal.After construction during the Wei Dynasty, although the irrigated area of ​​the Chengguo Canal has not exceeded, it has become the longest irrigation canal in Guanzhong.

In the Sui and Tang Dynasties, especially the Tang Dynasty, the economic and political power was unprecedentedly strong, and the political situation was stable for a long time, which created conditions for the revival and expansion of Guanzhong Water Conservancy.At the same time, due to the sharp increase in the population of Chang'an, the capital of the Tang Dynasty, which greatly exceeded that of Chang'an, the capital of the Han Dynasty, the food shortage problem in Chang'an in the Tang Dynasty was also more serious than that in the Han Dynasty.During the reigns of Tang Gaozong, Wu Zetian and Tang Xuanzong, because of the lack of food in the capital, they brought a large number of officials and troops to Luoyang, the eastern capital, more than once.Therefore, for the Tang government, it is urgent to increase the production of grain in Guanzhong.Under the impetus of the Tang government, Guanzhong in the Tang Dynasty, like the Western Han Dynasty, formed another climax of water conservancy construction.

After the efforts of the Wei Dynasty, the Chengguo Canal, which has a certain foundation, is still one of the key projects in the Tang Dynasty, and it has been treated repeatedly.The more important ones are: during the Zhenguan period of Emperor Taizong of Tang Dynasty (627-649 A.D.), craftsmen from Kyushu were recruited to repair the channels of Chengguo Canal; Water sources: In the sixth year of Emperor Zongdali of the Tang Dynasty (771 AD) and the thirteenth year of Emperor Yizong of Tang Dynasty (872 AD), Liumen Weir was overhauled twice, and water from Weichuan, Mogu, and Xianggu was added, which further enriched the city. The water volume of the national canal.After such a series of transformations, Chengguo Canal can irrigate more than 20,000 hectares of farmland in Wugong, Xingping, Xianyang, Gaoling and other counties, and the irrigated area is much larger than that of Zhengbai Canal.In the late Tang Dynasty, Chengguo Canal was renamed Weibai Canal.

Both the Zhengguo Canal and the Bai Canal were the most important farmland water conservancy projects in the Guanzhong area during the Qin and Han Dynasties.Due to some engineering problems, most of Zhengguoqu's downstream was scrapped during the Han Dynasty.Later, except for a part of its upper reaches connected to the Baiqu, it was gradually buried.Zheng Baiqu in the Tang Dynasty was actually a canal system dominated by Baiqu.At that time, Zhengbaiqu formed three tributaries, the northernmost one was Taibaiqu; the branch leading out from Taibaiqu and south of Taibaiqu was called Zhongbaiqu; the branch leading out from Zhongbaiqu was called Nanbaiqu in the south.After the Tang Dynasty, Zhengbaiqu was often called Sanbaiqu.Zhengbai Canal irrigates the farmlands of Yunyang (where the government is located in the north of today’s Jingyang County), Sanyuan, Xiagui (guigui) (where the government is located in the north of today’s Weinan County), Gaoling, Liyang, Jingyang and other counties (Figure 8).

The Zhengbai Canal is also an important irrigation canal on the Guanzhong Plain, and the Tang Dynasty also attached great importance to its maintenance and management.Like the Duchengguo Canal, there is also a special water conservancy organization here to manage it.In terms of engineering, a very strong diversion dam named Jiangjun (shasha) was built. Its length and width are 100 steps (each step is five feet), and it is built with block stones, and the blocks are connected by cast iron ingots.The channels have also been tidied up again and again to ensure the smooth flow of water.However, due to the fact that Jingshui contains too much sand, especially the rich and powerful built sluices and water mills on the canal, a large amount of canal water was lost. Therefore, despite frequent maintenance, the irrigated area of ​​Zhengbai Canal is still gradually shrinking, from more than 10,000 hectares. down to thousands of hectares.

Water mills and water mills are facilities that use water power to grind rice and wheat. The dignitaries can use them to process their own grain, and they can also rent them out. Competing to build them seriously affects the irrigation of the fields.For this reason, the bureaucrats who manage the channel have to order to stop it again and again, but it is rarely effective.In the end, the emperor had no choice but to intervene in person. For example, Tang Daizong not only issued an edict to demolish it, but also persuaded his daughter Princess Shengping and the son-in-law Duwei Guo Yan (son of Guo Ziyi) to take the lead in carrying it out, taking the lead among the dignitaries.According to the "Old Tang Book·Guo Yan Biography", "Therefore, more than 80 places in Shimen were crushed, all of which were destroyed."But soon, they built again.

In addition to the above-mentioned irrigation canals such as diverting Wei and Jing, the relatively important farmland water conservancy built in Guanzhong in the Tang Dynasty was between the Yellow River and the Luoshui River. First, in the seventh year of Tang Gaozu Wude (624 AD), water from the Yellow River was diverted from Longmen. There are more than 6,000 hectares of farmland in Guanhan City.Then, in the seventh year of Kaiyuan (719 A.D.) of Emperor Xuanzong of Tang Dynasty, Jiang Shidu, the magistrate of Tongzhou (where the government is located in today's Dali County, Shaanxi Province), also diverted water from Luoshui and the Yellow River to irrigate more than 2,000 hectares of rice fields in Chaoyi County (southeast of today's Dali County).In the west of Chang'an, there is also the Helan Canal, which diverts Fengshui (one called Fengshui or Fengshui) to irrigate more than 10,000 hectares of farmland in Weinan.In addition, in the Sui and Tang Dynasties, there was Guangtong Canal in Weinan, which was beneficial for both water transportation and irrigation.

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