Zhengguo Canal
The Zhengguo Canal, Zhengguoqu or Chengkuo Canal (), named after its designer, Zheng Guo, is a large canal located in Shaanxi province, China. The canal irrigates the Guanzhong plain, north of Xi'an. Together with the Dujiangyan Irrigation System and Lingqu Canal, it is one of the three biggest water conservation projects built before the Qin dynasty in ancient China. The canal connects the Jing river and Luo river, northern tributaries of the Wei River. History
Historian Sima Qian in his Records of the Grand Historian wrote of the Zhengguo Canal:

The plan to drain the resources of the State of Qin back-fired as Qin successfully completed the canal, which irrigated c. 27,000 square kilometres of additional agricultural land, providing the kingdom with sufficient resources to increase the size of its already massive armies. To this day the land surrounding the Zhengguo Canal is extremely fertile. The Jingshui River flows slowly and is heavy with sand, so the canal was frequently blocked. By the time of the Han dynasty, much of the canal had silted up and only a small section was still flowing. Under the supervision of engineer Bai Gong, a new canal was cut in 95 BC for irrigation. For the next 2000 years, re-cutting and moving the canal's feeder mouth upstream of the Jing River became a pattern as silt built up and river bed deepened, diminishing water flow and the efficiency of the system. See also
 History of canals in China
 Dujiangyan Irrigation System
 Lingqu Canal
 Grand Canal of China

References

Canals in China
Major National Historical and Cultural Sites in Shaanxi
Qin (state)