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 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 acclaimed as one of the three great water conservancy projects of the Qin Dynasty, alongside the Dujiangyan Irrigation System in Sichuan and the Zhengguo Canal in Shaanxi. It is also one of the oldest canals in the world. Having a history of over 2200 years, it has played an extremely important role in promoting economic and cultural exchanges between the Central Plains and the Lingnan region and has made indelible contributions to maintaining national unity and consolidating border defenses.
In 221 BC, after Emperor Qin Shi Huang unified the six states, he aimed to complete the unification of China. He then ordered General Tu Wei to lead naval troops southward to attack the Baiyue people in the Lingnan region. The Qin army, consisting of 550,000 soldiers, advanced towards the Baiyue territory through five routes. Among them, the route attacking Guangxi encountered fierce resistance from local tribes, forcing the Qin army to remain on high alert for "three years without taking off their armor" (Huainanzi: Renjianxun). The reasons for the unfavorable military situation included the Qin army's inadaptability to mountain warfare, their inability to acclimatize to the southern climate, and a significant number of sick soldiers. However, the more critical issue was the rugged terrain of the Lingnan region, the long transportation lines, and the insufficient supply of military provisions and fodder. Solving the transportation of military supplies became the key to determining the success or failure of this war. Emperor Qin Shi Huang decisively made the decision to "order Jian Lu to dig a canal for transporting grain" (Shiji: Pingjin Hou Zhufu Liezhuan). Under the supervision of Shi Lu, after arduous labor by the conscripted workers and the Qin army through several cold and hot seasons, the Lingqu Canal was successfully dug. The Qin army's provisions were transported by ship from the Xiang River through the Lingqu Canal into the Li River, continuously reaching the front lines, 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, establishing the commanderies of Guilin, Nanhai, and Xiang, and dispatching troops to garrison there. Thus, Emperor Qin Shi Huang completed his great cause of unifying the entire country.
The technology used in constructing the Lingqu Canal achieved brilliant accomplishments in the history of ancient hydraulic engineering and continues to shine brightly today. Xing'an County is located in the northern mountainous area of Guangxi, surrounded by towering mountains and crisscrossing rivers. To the southeast stands one of the Five Ridges, the Dupo Ridge, while to the south stretches the continuous Haiyang Mountains. To the northwest looms the majestic Yuecheng Ridge. The prominent geographical features are 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 central part of Xing'an County, a low-lying area with an altitude of only about 200 meters forms, which is the famous Xiang-Gui Corridor and has always been a major transportation route from Hunan to Guangxi. Due to these geographical characteristics, the Xiang River, originating from Haiyang Mountain, flows northward through Xing'an County along the Xiang-Gui Corridor and enters Dongting Lake in Hunan via Quanzhou County; the Li River, originating from the main peak of the Yuecheng Ridge, Mao'er Mountain, flows southward to Rongjiang, passes through Lingchuan County and Guilin City, and joins the Xijiang River at Wuzhou before entering 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." Although the Xiang River and the Li River are only 25 kilometers apart within Xing'an County, 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 convergence of numerous small streams, among which is the Shian Water. The Shian Water originates from the Fugui Ridge near Xing'an, and its straight-line distance from the Xiang River is only 2.5 kilometers, separated only by a ridge about 300 meters wide and 30 meters high called Yuecheng Ridge (also known as Shian Ridge or Linyuan Ridge), which is the watershed between the Xiang and Li Rivers. As long as this ridge is penetrated, the relatively higher Xiang water can be introduced into the Shian Water, thereby connecting the Li River. After careful surveying, the intelligent designers of 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 to introduce the Xiang water into the Shian Water. They also guided and modified the Shian Water so that ships 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, besides the channel, the Lingqu Canal already had structures such as the large and small Tianping (i.e., plow-shaped dikes), plow nose, Qin dike, water-discharging Tianping, and sluice gates, which are basically the same as what we see today. These scientifically coordinated and closely connected structures have made the Lingqu Canal an immortal hydraulic engineering project.