Linqu canal

Linqu canal

This entry is compiled and applied by "popular science China" Science Encyclopedia

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Lingqu, known in ancient times as qinzaoqu, Lingqu, Douhe, Xingan canal and Xianggui canal, is a great project created by ancient Chinese working people. Located in Xing'an County, Guangxi Zhuang Autonomous Region, it was chiseled into navigation in 214 BC. Lingqu flows from east to west, connecting Haiyang River (the source of Xiangjiang River, flowing from south to North) in the east of Xing'an County with Darong River (the source of Lijiang River, flowing from north to South) in the west of Xing'an County. Lingqu is one of the oldest canals in the world and has the reputation of "Pearl of ancient water conservancy buildings in the world".

On August 13, 2018, Lingqu and other four projects were included in the world irrigation project heritage list (the fifth batch) in 2018.

Project composition

The main project of Lingqu is composed of huazui, dadianping, xiaotianping, Nanqu, Beiqu, Shuiping, shuihan, Doumen, weir, qindi and bridge. Although the construction time is different, they are interrelated and become an indispensable part of Lingqu.

Huazui

Located in the upstream of fenshuitang dam of Haiyang River, 3km southeast of Xing'an County, it is called "huazui" because it is sharp in front and blunt in back and shaped like a plowshare. It is a masonry dam connected with the balance and has the function of water diversion. The direction of the sharp angle is opposite to the main stream of the Haiyang river. The Haiyang river is divided into two parts: one is from the south channel to Li, and the other is from the north channel to Xiang. The original length of huazui was 30 Zhang upstream of the existing huazui. When the canal was built in 1885-1888, huazui was submerged by silted sand and stone, so it was moved to its present position. However, today's shape is not sharp in front but blunt in back. One side is 40 meters long, the other side is 38 meters long, 22.8 meters wide and 2.3 meters high. It is surrounded by an inclined square platform made of massive limestone about 1.7 meters long, 60 cm to 1 meter thick and wide. To the south of the end of the platform, a 30 meter long stone dike was built after liberation. The length of the whole nozzle is 90 meters from the joint of the big and small scales to the tip of the nozzle.

Balance, balance

At the downstream of huazui is the barrage which intercepts the Haiyang river. The big balance is the right part of the barrage, and the small balance is the left part of the barrage. The big balance and the small balance are connected in a zigzag shape (the included angle is 108 degrees). Because they belong to the old road of Xiangjiang River, if they collapse slightly, there will be no water dripping into the canal. The left end of xiaopingping is equipped with Nandou, which is the water inlet of the south channel; the right end of datianping is equipped with Beidou, which is the water inlet of the north channel. From December 1985 to January 1986, Guilin water conservancy and Electric Power Design Institute of Guangxi Zhuang Autonomous Region and Hydropower Construction Engineering Office surveyed the Lingqu canal with scales. The results show that the top of datianping dam is 344 meters long and 12.9-25.2 meters wide, the maximum height of masonry is 2.24 meters, the elevation of upstream overflow surface is 213.7 meters, and the height of riverbed bottom is 213.5 meters. The elevation of downstream nose sill is 212.3m, and the elevation of riverbed scouring pit bottom is 210.9m. The top of xiaotianping dam is 130 meters long and 24.3 meters wide, the maximum height of masonry is 2.24 meters, the elevation of upstream overflow surface is 213.3 meters, the elevation of riverbed bottom is 212.8 meters, the elevation of downstream nose sill is 212 meters, and the elevation of riverbed scouring pit is 210.8 meters. The angle between the two axes is 108 degrees, the angle between the two axes and the river bed direction is 57 degrees for the big balance and 51 degrees for the small balance. The outside of the dam body is covered with mortar rubble and ichthyolith. The upstream rubble is stepped. The data are obtained from boreholes 4 and 7. The spacing between the two boreholes is 1 meter. Hole 4 is 0.5 meters in the front edge of Daping, mortar rubble is 2.24 meters high, and the bottom is mixed clay sand pebble. Hole 7 is 0.5 meters in the riverbed, 0-2.8 meters in depth, and 2.8-3.03 meters in depth. The top surface of the upstream strip stone is connected with a stone tenon to form a whole, and the block stone in the middle of the balance is nearly vertical masonry, which is called Ichthyoid stone, with a thickness of 0.7-1.3m. The upper part of the sand pebble dam body is composed of artificial mixed clay, and the lower part is composed of primary sedimentary sand pebbles. It's hard to distinguish between the upper and lower parts. One part of the cement between Tiaoshi and ichthyosite is sandy clay and lime, which has been weathered and loose; the other part is milky white and pink cement mixed with tung oil, which is compact in structure, strong in weathering resistance and especially hard.

Canal system

The south canal is 33.15 km long. It can be divided into four sections: the first section starts from the South steep, passes through feilaishi, shushuipingping and mahalanqiao, passes through Xing'an County, and reaches dawandiu, with a length of 3.15 km, a water surface width of 8-15 m and a water depth of 1-1.8 M. The canal line runs westward along the left bank of Xiangjiang River, most of which are semi excavated. The left side is excavated along the stone mountain or the ground; the right side is the stone canal embankment, which is commonly known as the Qin embankment. The inner and outer slopes are built with stones, and the middle is filled with soil. At the beginning, a section of stone embankment is 5 meters high, next to the Xiangjiang River. It is said that the construction failed twice, and the canal line was moved to the left side of feilaishi for the third time. The second section from Dawan steep, through Xiangjiang River and Lijiang River Watershed taishimiaoshan to Lijiang River small tributary shi'anshui stop. It is 0.95 km long, 6-13.5 m wide and 0.7-1.5 m deep. The whole line of this section is an excavated channel, which passes through taishimiao mountain and is about 30 meters deep, with a length of more than 300 meters. The excavation of this section is very arduous. The third section starts from shi'anshui, along a small natural river course, where inkstone water flows into xiayun bridge, flows through Lingshan temple, and flows into Qingshui River near zhaojiayan village, which is called Linghe river below. This section is 6.25 km long, which is widened by using natural rivers. At the same time, the curved section of the channel is added to slow down the slope. This section is 7-15m wide and 0.2m-1.3m deep. The fourth section starts from the confluence of Qingshui River, passes through luantang, Chetian and linghekou, and ends at the confluence of Da Rong River, which is called Linghe river. It is 22.8 km long, with some tributaries converging along the way, the water potential increases, the river is wide, the water surface is 25-50 m wide, and the water depth is 0.6-3 M. This section is a natural channel except that a new channel was excavated near Huanglong dyke to make the river zigzag to reduce the slope. The bottom elevation of the South Doukou of the canal is 212.08m, and the riverbed elevation of the linghekou at the confluence of the canal into the darongjiang river is 181.82m, with an average slope of 0.91 ‰. The Yanguan main canal, with a total length of 10 kilometers, divides water from 4.97 kilometers of the south canal (the lower reaches of sanlidou). It was built in 1952. There are two branch canals, Lianhuatang and Xianqiao. The first branch canal is located 2.23km away from the south canal; the second branch canal is located in the middle of qutiandong, which was rebuilt into a common drainage and irrigation channel in 1958; the third branch canal is located 3.1km away from the south canal, passing dawandiu and Tangshi to Dadong village, Jieshou Town, with a total length of 13.5km, which was completed in 1956. The total length of the North Canal is 3.25 km, which is excavated on the broad terrace on the North Bank of Xiangjiang River. From the North steep to the north, through Dayu village, Huaqiao, to shuipo village into Xiangjiang River. It is 10-15m wide. The elevation of beidoukou is 211.8m, the elevation of canal tail is 206.31m, and the average slope is 1.69 ‰. Two continuous S-shaped canal sections are excavated in the middle section to reduce the gradient.

Discharge balance and overflow dam

At 0.89 km of the south canal, there is a discharge balance to release the flood. When the water depth in the canal exceeds the top of the weir, the canal water will be discharged into Xiangjiang River. The weir top is 5 meters wide and built with big stones. The weir is 42 meters long and 17.6 meters wide at the bottom. The original stone bridge on the weir has been changed into reinforced concrete pedestrian bridge after liberation. At 1.95 km away from the south canal, it meets shuangnujing River and has built a marsh bridge overflow weir to release the flood of shuangnujing river. The weir crest is 4 meters wide, 1.5 meters high and 19.5 meters long. It is built with big stones. When it was built in the early Qing Dynasty, a pedestrian stone slab bridge was erected on the weir, and it was rebuilt into a reinforced concrete highway bridge after liberation. The overflow weir 12.43km away from the south canal is called Huanglong dike. It is built with big stones, with a top width of 3.5m and a weir length of 87.6m. The overflow weir at 0.21 km of the North Canal is called Zhuzhi weir. The weir is 8 meters wide and 15 meters long, and is built with stones.

Water culvert

It is also called Tian Han, Qu Yan, or Tang Kong. It is set in the dike and built with stone blocks for irrigation. In the 29th year of Hongwu in Ming Dynasty (1396), when Yan Zhen built the canal directly, 24 irrigation culverts were built. After liberation, due to the construction of irrigation channels, except for the intake gates, most of the other water culverts were blocked. So far, there are still seven in the south channel and two in the north channel.

Doumen

Doumen, or Doumen, is a building used to raise the water level, store water and navigable on the South and North canals, which has the function of ship lock. According to historical documents, Doumen first appeared in the first year of Baoli (825) of Tang Dynasty. When it was rebuilt in the ninth year of Xiantong (868), there were 18 Doumen. In the third year of song Jiayou's reign (1058), there were 36, the largest number since records. By 1885, there were still 35 Doumen. After liberation, according to the investigation in 1975, there were 37 Doumen recorded in historical documents, including 32 in the south channel, 5 in the north channel, 13 in complete or generally complete preservation, and 14 in the north channel reconstructed in 1977. The rest only have a few stones or footstones at the bottom. It can be judged that there were Doumen in this place, but most of them have no relics. From the existing steep slope

Chinese PinYin : Ling Qu