The Lingqu Canal, also known as the Qin Ditch or Du River, is located in Xing'an County of Guilin City. It can be directly reached 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 (214 BC), it is one of the three major water conservancy projects of the Qin Dynasty, along with the Dujiangyan Irrigation System in Sichuan and the Zhengguo Canal in Shaanxi. It is also one of the oldest canals in the world. To date, it has a history of 2200 years, playing an extremely important role in promoting economic and cultural exchanges between Central Plains and Lingnan regions, and making 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 to attack Baiyue in the south" and marched into the Lingnan region. The Qin army's 550,000 troops were divided into five routes to advance towards the Baiyue lands. Among them, the Qin army advancing towards Guangxi encountered fierce resistance from local tribes, forcing the Qin army to remain armed for "three years without taking off armor and releasing crossbows" (from the Huainanzi: Renjianxun). Investigating the reasons for the unsuccessful military campaign, it was partly due to the Qin army's inability to adapt to mountain warfare, their unsuitability to the southern climate, and a high number of sick soldiers. However, more importantly, the rugged terrain of the Lingnan region, long transportation lines, and insufficient supply of military provisions played a significant role. 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 "send Jian Lu to dig a canal to transport grain" (from the Records of the Grand Historian: Pingjin Hou Zhufu Liezhuan). Under the direction of Shi Lu, through the arduous labor of the conscripted workers and the Qin army, after several cold and hot seasons, the Lingqu Canal was successfully dug. The Qin army's food supplies were transported by ships on the Xiang River, passed through the Lingqu Canal, entered the Lijiang River, and were continuously delivered to the front line, ensuring the needs of the front-line military operations. In the 33rd year of Emperor Qin Shi Huang, the Qin army finally unified the Lingnan region, established the commanderies of Guilin, Nanhai, and Xiang, and stationed troops there. Thus, Emperor Qin Shi Huang completed the great cause of unifying the whole country.
The technology of digging the Lingqu Canal achieved brilliant accomplishments in ancient water conservancy history and still shines 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 Ling, while to the south lies the continuous Haiyang Mountain. To the northwest stands the majestic 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 forms, which is the famous Xiang-Gui Corridor, historically a key transportation route from Hunan to Guangxi. Due to this geographical feature, the Xiang River originating from Haiyang Mountain flows northward to Xing'an County, following the Xiang-Gui Corridor through Quanzhou County and enters Hunan's Dongting Lake; the Lijiang River originating from the main peak of Yuecheng Ridge, Ma'er Mountain, flows southward to Rongjiang, passes through Lingchuan County and Guilin City, and converges into the West River at Wuzhou, eventually flowing into the Pearl River in Guangdong. The Xiang River flows northward, while the Lijiang River flows southward, hence the saying: "Xing'an is ten thousand feet high, water flows in two directions." Although the Xiang River and Lijiang River are only 25 kilometers apart in Xing'an County, it was quite difficult to directly dig a canal connecting the two rivers during the Qin Dynasty. Fortunately, the Lijiang River has a tributary called Ling River, formed by the confluence of many small streams, among which one is named Shian Water. Shian Water originates from Fugui Ridge near Xing'an, with a straight-line distance of only 2.5 kilometers from the Xiang River. It is separated by a ridge over 300 meters wide and 30 meters high called Yuecheng Ridge (also known as Shian Ridge or Linyuan Ridge), which serves as the watershed between the Xiang and Lijiang Rivers. As long as this ridge is pierced through, the higher-altitude Xiang River water can be introduced into the Shian Water, thereby connecting the Lijiang River. After careful surveying, the intelligent 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 cut through the Taishi Temple Mountain on Yuecheng Ridge, introducing the Xiang River water into the Shian Water. The Shian Water was then diverted and modified so that boats could pass through it and enter the Ling River, thus connecting the Xiang and Lijiang Rivers. According to historical records from the Tang Dynasty, in addition to the channel, the Lingqu Canal already had large and small Tianping (i.e., plow dikes), plow nose, Qin dike, water discharge Tianping, and sluice gates, which are basically the same as what we see today in the Lingqu Canal. These structures are scientifically coordinated and closely connected, making the Lingqu Canal an immortal water conservancy project.