Zhengguo Canal is located in the middle of Central Shaanxi Plain and it is one of the earliest large-scale dam-less water diversion and irrigation systems in China. Zhengguo Canal was first constructed in 246 BC. and its construction laid the economic foundation for the rise of the Qin Kingdom and the unification of ancient China. The Canal has worked effectively as an irrigation infrastructure for more than 2000 years.
The head of the Canal was located about 1km to the northwest of Wangqiao Town, Jingyang County and the Canal bottom is already about 15m above the bed of the Jing River today. In 95 BC, the Canal was rehabilitated and the canal head was moved upstream by 1297 meter; in the 11th century, the Canal was renovated again, and the bedrock was dug to widen the mouth and the course of the canal. In the 14th century, the intake was moved upstream again. In the 15th century, the canal head was further relocated upstream by 990 meter and a tunnel was excavated for water diversion. This renovation took 18 years to complete. In 1517 and 1822 respectively, another two water diversion tunnels were excavated to shorten the distance the water flows by making it run straight. In 1932, the Canal was rehabilitated again. A water diversion hub with dam was built to the upstream of the original canal intake. And the Canal was renamed Jinghui (the benefits of Jing River). In 1966, the dam was destroyed by the flooding Jing River, and thus a concrete overflow dam was reconstructed 16 meter to the downstream. Other than water diversion and irrigation, this canal also worked for power generation. In the past 2,000 years, the riverbed of the Jing River has cut downwards by nearly 20 meter and the head of Zhengguo Canal has moved upstream by about 5km.
Zhengguo Canal diverted water from the Jing River to the east. When it was first built, the general main canal was built along the contour line and crossed many natural rivers. Its tail water flew into the Luo River. The canal was 125km long and irrigated a farmland area of 186667 hectare. In the dynasties that followed, the Canal and its irrigation system were adjusted for a few times and the irrigation area dwindled. Today, its irrigation area covers the parts to the east of the Jing River and the parts to the west of the Shichuan River, including 48 townships of six districts and counties in a total area of 1,180 km2 and an irrigation area of 97000 hectare.
Zhengguo Canal Irrigation System comprises the canal head, irrigation canal system and auxiliary infrastructures. Currently, the Canal has a designed water diversion discharge of 50m3/s. The irrigation and drainage canal system comprises one general main canal and 5 main canals with a total length of 92.324km; 25 branch canals with a total length of 336.21km; 593 sub-lateral canals with a total length of 1,477.5km. There are 1,984 control works on the main and branch canals. These project infrastructures constitute an integral work to ensure safety of the irrigation area during drought and flood seasons. Today, 14 steles are preserved as a record of the historic events and irrigation regulations of the canal in all the dynasties and a multitude of historic literatures are also available. These written records are all important constituents of the heritage of the Zhengguo Canal Irrigation System.
Historically, Zhengguo Canal had a stringent administrative system which kept improving with the vicissitude of time. Generally, Zhengguo Canal was administered by a combo of government and private resources. The government presided over the construction of main sections and large-scale works of the irrigation area, promulgated regulations and supervised the implementation thereof. The farmers in the irrigation area performed annual maintenance of the lower-level canals and infrastructures under the guidance of the government and distributed the irrigation water. According to historic records, the government already issued a ~~water distribution order~~ in the Western Han Dynasty (the 2nd century BC). In the Tang Dynasty, the Central Government promulgated the ~~Water Law~~ and the ~~Six Statutes of the Tang Dynasty~~, specifically laying down regulations on the construction of sluice gates, weirs, dams and other water flow control works in the irrigation area, the rules on distribution of irrigation water, the designation and dismissal of administrative organs and officials and their duties, assessment and supervision and the coordination of irrigational and hydraulic benefits of the canals. In the subsequent Song, Yuan, Ming and Qing Dynasties, more detailed regulations were issued on the annual maintenance, laborer recruitment, distribution of irrigation water, project and water environment safety and water administration. In 1934, Shaanxi Water Resources Bureau set up the ~~Jinghui Canal Administration~~ which has been preserved until today (the Canal was renamed Jinghui at that time). In 1951, Irrigation Committee of Jinghui Canal Irrigation Area was established, comprising the main officials in charge of Jinghui Canal Administration and the governments of various local cities and counties in the irrigational zone. The Committee was liable for proposing irrigational regulations and coordinating the irrigation water distribution among various areas. Today, section chiefs are selected from farmers and designated by the Administration to see to the patrol, maintenance, and water distribution of a specific area of the System. Such a constantly-updated administration system has guaranteed the irrigation performance of the System.