The Lingqu Canal, also known as the Qinzhao Channel or Duh River, is located in Xing'an County, Guilin City. It can be reached directly by National Highway 322, and it is 60 kilometers away from the center of Guilin City. Completed in the 33rd year of Emperor Qin Shi Huang's reign (214 BC), it is one of the three great water conservancy projects of the Qin Dynasty along with Dujiangyan in Sichuan and Zhengguo Canal in Shaanxi, and is one of the oldest canals in the world. It has a history of 2200 years and has played an extremely important role in promoting economic and cultural exchanges between the Central Plains and the Lingnan region. It has made indelible contributions to maintaining national unity and consolidating border defense.
In 221 BC, after Emperor Qin Shi Huang unified the six states, in order to complete the great cause of unifying China, he then "sent General Tu Wei to lead the naval troops southward to attack the Baiyue tribes", advancing into the Lingnan region. The Qin army of 550,000 soldiers advanced towards the Baiyue territories in five routes. Among them, the route attacking Guangxi encountered fierce resistance from local tribes, forcing the Qin army to "remain armed for three years" (from Huainanzi: Renjianxun). Investigating the reasons for the military setbacks, they were related to the Qin army's lack of adaptation to mountain warfare, unsuitability to southern climate and soil, and a large number of sick soldiers. But more importantly, the rugged terrain and long supply lines in the Lingnan region prevented the timely supply of military provisions. Solving the problem of transporting military provisions became the key to deciding the outcome of this war. Emperor Qin Shi Huang decisively made the decision to "send Jian Lu to dig a canal to transport grain" (from Records of the Grand Historian: Biography of Lord Pingjin).
Under the supervision of Shi Lu, after the hard work of the conscripted laborers and the Qin army, enduring several cold and hot seasons, the Lingqu Canal was successfully dug. The Qin army's provisions were transported by ships on the Xiang River, through the Lingqu Canal into the Li River, continuously reaching the front line, ensuring the needs of the front-line military operations. In the 33rd year of Emperor Qin Shi Huang's reign, the Qin army finally unified the Lingnan region, setting up the commanderies of Guilin, Nanhai, and Xiang, and stationed troops there. Thus, Emperor Qin Shi Huang completed his great cause of unifying the whole country.
The canal excavation technology of the Lingqu Canal achieved brilliant success in the history of ancient hydraulic engineering and still shines brilliantly today. Xing'an County is located in the northern mountainous area of Guangxi, surrounded by towering mountains and crisscrossing rivers. To the southeast stands the Dupo Ridge, one of the Five Ridges, while to the south stretches the continuous Haiyang Mountain, and to the northwest looms the Yuecheng Ridge. The prominent feature of the terrain is that the southeastern part is higher in the south and lower in the north, while the northwestern part is higher in the north and lower in the south. In the middle of Xing'an County, a lowland with an altitude of only about 200 meters has formed, which is the famous Xiang-Gui Corridor, historically a major transportation route from Hunan to Guangxi. Due to this geographical feature, the Xiang River originating from Haiyang Mountain flows northward to Xing'an County, along the Xiang-Gui Corridor through Quanzhou County into Dongting Lake in Hunan; the Li River originating from Maer Mountain, the main peak of the Yuecheng Ridge, flows southward to Rongjiang, through Lingchuan County and Guilin City, converging into the Xi River at Wuzhou, and finally into the Pearl River in Guangdong. The Xiang River flows northward, while the Li River flows southward, hence the saying: "Xing'an is ten thousand feet high, water flows in two directions." The Xiang River and the Li River are 25 kilometers apart in Xing'an County, and directly digging a canal to connect the two rivers during the Qin Dynasty would have been quite difficult. Fortunately, the Li River has a tributary called the Ling River, formed by the confluence of many small streams, among which one is named Shian Water. The Shian Water originates from Fugui Ridge near Xing'an, with a straight-line distance of only 2.5 kilometers from the Xiang River, separated only by a ridge over 300 meters wide and 30 meters high called Yuecheng Ridge (also called Shian Ridge or Linyuan Ridge), which is the watershed between the Xiang and Li Rivers. As long as this ridge is breached, the Xiang River water at a higher altitude can be diverted into the Shian Water, thereby connecting the Li River. After careful surveying, the clever designer at the time discovered this secret. Therefore, the Qin army built a dam across the Xiang River to raise the water level, dug a 5-kilometer-long channel, and excavated the Taishi Temple Mountain on the Yuecheng Ridge, diverting the Xiang River water into the Shian Water, and guiding and transforming the Shian Water so that boats could pass through it into the Ling River, and then into the Li River, thus connecting the Xiang and Li Rivers. According to historical records from the Tang Dynasty, apart from the channel, the Lingqu Canal already had structures such as the large and small Tianping (i.e., plowshare embankments), plowshare nose, Qin dike, water discharge Tianping, and sluice gates, which are basically the same as what we see today in the Lingqu Canal. These buildings are scientifically coordinated and closely connected, making the Lingqu Canal an immortal hydraulic engineering project.