Zheng Bai Qu

　　Zheng Bai Qu, a large irrigation project in the ancient Guanzhong Region (today's Shaanxin Province), was the combined name of Zhengguo Qu and Bai Qu. (Qu means canal.)

　　In 246BC during the Warring States Period (475-221BC), Zheng Guo, a hydraulic engineer from the Han State, began the construction of Zhengguo Qu for the Qin State and finished the project in more than 10 years. The canal was 150 kilometers long, linking the Jingshui River and the Luoshui River. It could irrigate 40,000 hectares of farmlands.

　　Thanks to the function of the canal, the production of the surrounding farmlands surged, providing enough funding for the Qin State which defeated the other six warring states and for the first time in China's history set up a unified county -- the Qin Dynasty (221-206BC).

　　In 95AD, the Eastern Han Dynasty built Bai Qu, linking the Jingshui River and Weishui River. The new canal was 100 kilometers long and could irrigate 4,500 hectares of farmland.

　　Since then, the two canals were called by a joint name: Zheng Bai Qu. During the Tang Dynasty (618-907), Zheng Bai Qu had three branches: Tai Bai Qu, Zhong Bai Qu and Nan Bai Qu, with an irrigation area of over 10,000 hectares. In the later dynasties, Zheng Bai Qu was revamped several times.