At the end of the warring States period, the two major water conservancy projects built by the state of Qin were

Dujiangyan and Lingqu are also called the three major water conservancy projects in ancient China. They have one thing in common: they were all built by Qin.

The first two are pure agricultural irrigation facilities. Dujiangyan, listed as a "World Heritage", created the legend of "Land of Abundance" and provided a strong material foundation for Qin's unified war. Today, people are still benefiting, and Dujiangyan is the most famous. We can only say that the origin of Zheng Guoqu is a super political joke. As a matter of fact, the completion of Zheng Guoqu turned the arid plain into fertile land, and the grain output increased greatly, which directly supported the war of Qin to unify the six countries. The original intention of Lingqu construction is entirely for military purposes.

Lingqu was built after Qin Shihuang unified the Central Plains and attacked Lingnan area.