Chapter 31 Section 4 Water Conservancy in Song, Yuan, Ming and Qing Dynasty
During the Song, Yuan, Ming, and Qing dynasties, when the capitals were established in the eastern part of my country, the political status of Guanzhong declined. Generally speaking, the area of irrigated land in Guanzhong is gradually shrinking.
In the Song Dynasty, although the water conservancy in Guanzhong was not as vigorous as that in the Han and Tang Dynasties, because it was the military base of the Song Dynasty's war against Xixia, with heavy troops stationed and a lot of military food and fodder, some forces had to be allocated to build local water conservancy.The Song Dynasty focused on building Sanbai Canal here.It rebuilt the head of Sanbai Canal.Because the Jingshui kept brushing the deep riverbed and the bottom of the canal was constantly silted up, the mouth of the Sanbai Canal could no longer draw water, so Song built a new canal above the original canal mouth to connect to the old canal below.The project of this section of the new canal is relatively complete. In order to prevent erosion, it is constructed of stone materials; in order to reduce the flow of sediment into the downstream, a clear pond is set up; in order to prevent floods from rushing into the irrigation area, a sluice gate is built.In terms of canal system, the Tang Dynasty focused on the Zhongbai Canal, and the Song Dynasty transformed the Taibai Canal into the most important channel.Taibaiqu is located in the north of Zhongbaiqu, with a slightly higher terrain and a larger control area, which can irrigate more farmland.After the efforts of the Song Dynasty, the irrigated area of the Sanbai Canal increased significantly. According to "Cai Pu Xiu Canal Inscription", by the end of the Northern Song Dynasty, more than 35,000 hectares of farmland could be irrigated.Therefore, Sanbaiqu was renamed Fengliqu.However, due to the failure of other irrigation canals to overhaul, the irrigation effect has declined, so the water conservancy in Guanzhong is still showing a landslide trend.
In the Yuan and Ming dynasties, the mouth of the diversion canal had to be moved up again and again because the Jingshui continued to brush the deep riverbed and the sediment continued to silt up the bottom of the canal.Fengli Canal in Song Dynasty was called Wang Yushi Canal and Guanghui Canal in Yuan and Ming Dynasties respectively.According to relevant records in the Yuan and Ming Dynasties, the south of Tang Zhengbai Qukou is more than 2,700 steps away from Qin and Han Zhengbai Qukou (five feet is a step); ; Guanghui Qukou is 384 steps south of Wang Yushi Qukou.At the end of the Yuan Dynasty, the mouths of these canals were much higher than the water surface of Jingshui. The actual measurements at that time showed that the mouths of Zhengbai Quays were more than 50 feet in the Qin and Han Dynasties, more than 13 feet in the mouths of Zhengbai Quays in the Tang Dynasty, and 7 feet in the mouths of Fengli Canals. The mouth of the canal is three feet.
The diversion outlets of Wangyushi Canal and Guanghui Canal are caves with rock structure, and the tunneling project is very arduous. The former has been dug intermittently for 26 years, and the latter has been dug for 17 years.In addition to digging holes, the headworks of the canals are also built with weirs.However, the structures of the weirs in the Song, Yuan, and Ming dynasties were not as strong as those of the generals of the Tang Dynasty. They were a kind of stone weir [qun group Yinping], built with bamboo and wood containers filled with stones. Frequent maintenance.
Regardless of Wang Yushi Canal or Guanghui Canal, the area of irrigated fields is not large, at most about 8000-9000 hectares.
In the Ming Dynasty, in addition to the diversion project, some attention was also paid to the construction of the Wei diversion project, especially the Tongji Canal opened during the Chenghua period of Emperor Xianzong of the Ming Dynasty (1465-1487 A.D.).This irrigation canal runs from Baoji in the west to Wugong in the east, with a length of 210 miles. There are also four branch canals running from north to south, irrigated more than 1,600 hectares of land.In fact, the Tongji Canal is a partial restoration of the Chengguo Canal in the Han and Tang Dynasties.
By the Qing Dynasty, Guanzhong water conservancy had undergone major changes.Because Jingshui, Weishui, Luoshui, etc. all have high sediment content, the irrigation districts that use these rivers as water sources have accumulated more and more serious sand damage.And because the river beds of these waterways are constantly being cut down, the difficulty of diverting water for irrigation canals is also increasing day by day.The above problems are difficult to solve by ancient hydraulic technology.In the Qing Dynasty, people had to gradually abandon large-scale water conservancy projects such as diverting Jing, diverting Wei and diverting Luo, and devoted themselves to the work of opening up new water sources.In Weibei, they developed a large number of springs; in Weinan, they also dug a number of mountain streams to irrigate the fields.However, the flow of spring water and stream water is relatively small, so the scale of irrigation projects using them as water sources is often small.Therefore, although the number is overwhelming, the irrigated area is still very limited.Not only that, the ability of medium and small water conservancy to resist floods and droughts is also very weak, and they are prone to disasters.
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