The Lingqu lies across the watershed between the Xiang and the Li. In 214 BCE the Qin dug it for its campaign in Lingnan, cutting across the watershed to link the Xiang and the Li and so the Yangtze and Pearl river systems.
Once the canal was finished, there was a waterway boats could use between the Yangtze and Pearl river systems. The Qin dug it to carry supplies for its campaign in Lingnan.
In 825 (Baoli 1 of the Tang), Li Bo, the Guiguan commissioner, rebuilt the Lingqu, built the ploughshare dyke and set lock gates at the mouths of the north and south channels. Doumen is the name for these gates at the channel mouths.
In Xiantong 9 (868) Yu Mengwei repaired it again and the gates were increased to eighteen. The Lingqu is still in use; this record covers its cutting and the two repairs of the Tang.
The Lingqu Canal Project is the class in the chapter on Infrastructure on the Lingqu: the canal the Qin dug in 214 BCE for its campaign in Lingnan, together with its rebuilding in the Tang. It crosses the watershed between the Xiang and Li rivers and joins the Yangtze and Pearl river systems, and in the Tang a ploughshare dyke was built and lock gates were set.
