Where is the longest underground river in China?

The longest underground river - qanats.

Kanjing is a kind of well where people in Turpan, Xinjiang, mine groundwater. This kind of well is divided into open channel, culvert and straight well, among which the excavation of culvert project is the most arduous. The qanats are a few kilometers short and dozens of kilometers long.

Today, Turpan has an underground river composed of more than 1,000 qanats, with a total length of more than 3,000 kilometers, and is known as the longest underground "river" in China.

Karez. Qanats, called "Kanez" in Uygur language, originally means underground waterway, and is a unique underground water irrigation system. The karez is composed of four parts: a shaft, a culvert, an open channel, and a waterlogging dam (reservoir), and it is an underground water conservancy project that takes advantage of the topography of the north and the south to lead the groundwater out of the surface without power.

Shafts are used to excavate culverts, transport sand and gravel and ventilate. The wellhead is rectangular, generally 1 meter long and 1 meter wide, and a shaft is excavated every 20 30 meters, the more upstream, the longer the shaft distance, the more downstream, and the shorter the shaft interval. The culvert is the main body, that is, the underground channel, which is generally high and wide and 3 5 kilometers long.

The longest culvert in the Qanats in the Turpan area is 25 kilometers, and the shortest is only 1,200 meters. Nullahs are above-ground diversion channels that divert water into dams (reservoirs) or directly irrigate fields. The basic principles of qanats are:

Groundwater from the basin is dug horizontally upstream, into the aquifer and extending as far as possible, and the groundwater in the aquifer continues to seep into the culvert and flow out along the canal.

There are three conditions that must be met for the formation of qanats: first, there are abundant groundwater sources; second, there is a certain slope; Third, there is anti-seepage and anti-collapse soil. And Turpan has these conditions one by one.

Regarding the origin of the qanats, there are three theories: one is the Central Plains theory. According to the "Historical Records of the River Canal Book", in the Western Han Dynasty, a person named Zhuang Xiongzhen wrote to Liu Che, Emperor Wu of the Han Dynasty, suggesting that the Longshou Canal should be dug to divert the water of the Luo River to irrigate the Dali Plain.

He said that if the canal is completed, more than 1 million mu of saline-alkali land can be transformed into fertile land. Emperor Wu of the Han Dynasty made this suggestion and ordered the requisition of more than 10,000 migrant workers to repair the canal. Because the canal bank near the mountain often collapses, the canal water can not pass, Zhuang Xiongzhen took people to measure the route of the channel on the mountain first, along this line to dig a straight well, and then dig each well from the ground, so that it becomes an underground channel connected with the surface channel on both sides and three sides of the mountain, and the canal water flows through the mountain from this underground channel to reach the Dali Plain.

Later, with the opening of the Silk Road and the migration of a large number of people from the interior to the Western Regions to engage in reclamation, this water conveyance technology was gradually introduced to Xinjiang.

China's longest underground river - Xinjiang Karez, with a total length of about 5,000 kilometers! This "project" is in the Xinjiang region of our country, and its construction is called "the longest underground river in China".

The karez wells in Xinjiang are distributed in very arid areas, and it is a special water conservancy project that uses culverts to divert underground undercurrents and carry out artesian irrigation according to the characteristics of local hydrogeology, when people lacked the means to introduce the surface runoff from various mountain streams from the Gobi to the irrigation area for a long distance and the lack of water-lifting machinery.

As we all know, the water resources in Xinjiang are not as abundant as those in the eastern region, so the use of water resources is very important for the people living here, and the construction of this underground river water conservancy project is the result of people making full use of water resources through wisdom. Its construction gave Turpan an oasis and solved many difficulties caused by the lack of water.

At that time, its construction improved the lives of many people and allowed the culture and civilization here to endure for a long time. It is reported that this kind of water conservancy project appeared in relatively arid places, because at that time, people's technology was not enough to be able to drain the surface water on the ground to other places, so the lost rent thought of diverting the water by melting the mountain snow on the surface and underground and inspecting the way underground.

Related Answers to Hongming

The karez water conservancy system is not only a splendid cultural achievement of the Chinese civilization system, but also an important part of the world civilization. The prosperity of Qanats is based on the social, economic and cultural development of the Turpan area, and at the same time, Karez has also witnessed the economic and cultural exchanges between the East and the West.

The Turpan civilization, which has a long history for many years, further illustrates the close relationship between the development and utilization of nature, especially water resources, and the replacement of civilizations in arid areas.

The above content reference: Encyclopedia - Qanats.

Duandisu underground river.

Du'an has a unique karst landform, with a total length of 241 kilometers of underground rivers, which is the longest underground river that has been explored in China. In addition, there are more than 200 underground river skylights with high distribution density and excellent ornamentation, which can be called the world's first.

Located in Du'an Yao Autonomous County, Guangxi Zhuang Autonomous Region, Du'an Disu Underground River is the largest underground river in Guangxi, with a dendritic underground river system with a catchment area of 1054 square kilometers and 12 tributaries. The underground river water level is buried to a depth of 30 meters to 50 meters, and the individual depth is more than 80 meters, and the water level changes by 40 meters to 100 meters. The flow rate is 400 cubic meters per second and 500 cubic meters per second during the flood season, and about 4 cubic meters per second during the dry season.

Its main stream originates in the mountainous area of Qibailong, flows from northwest to southeast from the underground through Qibailong, Baoan, Dongmiao, Disu, Sanlong and other townships, and flows into the Hongshui River in Qingshui Village of Disu Township, with a total length of kilometers and a drop of 342 meters.