Zhengguo Canal

The Zhengguo Canal, also called Zhengguoqu or the Chengkuo Canal, is a large irrigation canal in Shaanxi province, China, named after its designer, the water engineer Zheng Guo. It irrigates the Guanzhong plain north of Xi'an and connects the Jing River with the Luo River, both northern tributaries of the Wei River. Together with the Dujiangyan Irrigation System and the Lingqu Canal it is counted among the three biggest water conservation projects built before the end of the Qin dynasty. The historian Sima Qian recorded that the state of Han sent Zheng Guo to persuade Qin to dig a long canal, hoping to drain Qin's resources and stop its eastward attack. The plot was found out while the work was half done, but Zheng Guo argued that the finished canal would benefit Qin, and the work went on. The canal irrigated about 27,000 square kilometers of extra farmland, made the surrounding land very fertile and helped Qin grow rich and strong. The Jing River carries heavy sand, so the canal often silted up. In 95 BC the engineer Bai Gong supervised a new canal cut for irrigation, and for the next two thousand years the feeder mouth was repeatedly restructured as silt built up.