Dongting Lake

Dongting Lake

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

to examine

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Dongting Lake, known as Yunmeng, Jiujiang and chonghu in ancient times, is located on the South Bank of Jingjiang River in the middle reaches of the Yangtze River. It spans Yueyang, Guluo, Xiangyin, Wangcheng, Yiyang, Yuanjiang, Hanshou, Changde, Jinshi, Anxiang and Nanxian counties. The name of Dongting Lake began in the spring and Autumn period and Warring States period, and got its name from Dongting mountain in the lake.

Dongting, Hubei Province, receives the water from Songzi, Taiping, Ouchi and Tiaoxin of the Yangtze River. In the South and West, it connects the small tributaries of Xiang, Zi, yuan, Li rivers and Miluo River, and flows into the Yangtze River from Chenglingji of Yueyang City.

In ancient times, Dongting Lake was called "800 Li Dongting". At the end of the 1990s, according to the estimation of the water conservancy department, it covers an area of 2579.2 square kilometers (2740 square kilometers)

）Generally speaking, it is the second largest freshwater lake in China. If we add the four rivers of Hunan, Ziyuan, Yuanli and the "four estuaries of the Yangtze River" with an area of more than 1300 square kilometers of Floodway (18780 square kilometers)

）2 square kilometers (or 4040 square kilometers)

. The perimeter of the lake basin is 803.2 km, with a total volume of 22 billion cubic meters, including 17.8 billion cubic meters of natural lakes and 4.2 billion cubic meters of river channels.

Dongting Lake is an important regulating and storing Lake in the Yangtze River Basin. It has strong flood storage capacity. It has saved the Yangtze River from numerous flood disasters. Jianghan Plain and three towns in Wuhan have been able to pass the flood safely.

Dongting Lake is an important strategic place in history and the birthplace of Chinese traditional culture. There are many scenic spots in the lake area. Yueyang Tower is an important tourism and cultural resource. It is also the birthplace of Chinese traditional agriculture, a famous land of fish and rice, and the most important commodity grain and oil base, aquaculture and breeding base in Hunan Province and even in China.

Business card picture: Dongting Lake from Junshan

The origin of the name

Dongting Lake is historically known as Yunmeng, yunmengze, Jiujiang, wuzhu, Wuhu, Sanhu, chonghu and Taihu.

There are many versions of the name of Dongting Lake. There are records of "Yunmeng" in historical records, Zhouli, Erya and other ancient books. Dream is the meaning of "HuZe" in Chu dialect at that time, which is interlinked with the word "Shou". "In the first year of the spring and Autumn period, Chu Zi and Zheng Botian had a dream in Jiangnan.". He also said: "in the fourth year of the reign of emperor Ding, Chu Zi was involved in the Suiji River and entered the clouds. "Hanyang annals" says: "the cloud is in the north of the river, the dream is in the south of the river. "Together, they are called Yunmeng. At that time, yunmengze covered an area of 40000 square kilometers, which is recorded in the book of geography today: "to Qizhou in the East, to Zhijiang in the west, to the south of Jingshan mountain and to the north of Qingcao are all ancient Yunmeng. "Sima Xiangru's" Zi Xu Fu "said:" the cloud dream is eight or nine hundred Li. "In the late Warring States period, yunmengze was divided into North and south parts due to sediment deposition. The north part of the Yangtze River became a swamp, and the south part of the Yangtze River remained a vast lake. Since then, it is no longer called Yunmeng, but Dongting Lake, because there is a famous Junshan in the lake, formerly known as Dongting mountain. "A brief account of Xiangfei Temple" says: "Dongting is one of the immortal caves. It is called Dongting because it is the court of Dongting. Later generations with its vast ocean, torrential floods, no known, then refers to the mountain of Dongting, named Lake Dongting. "This is the origin of the name of Dongting Lake.

Formation and evolution

Dongting Lake is a faulted basin on the south axis of Yangtze paraplatform, which was formed during the Yanshanian movement and continued to the Himalayan movement. The Cretaceous is the period of basin development and expansion. Since the Quaternary, under the action of neotectonic movement, the Dongting lake depression basin has once again subsided and accepted sedimentation. It has become the area with the widest distribution, the largest thickness and the most complete sedimentary sequence in the Quaternary in Hunan Province. There are more than four evolution processes of lacustrine formation in depression and terrigenous formation in uplift, and the corresponding depression basin disintegrates to form fault depression basin. In the early Pleistocene, lakes were formed in mupinghu, Lixian and Yuanjiang depressions. In the Middle Pleistocene, lake transgression extended to Hanshou, Dingcheng, Anxiang and Xiangyin, and the outflow flowed from Anxiang to the Yangtze River through Lixian depression. In the late Pleistocene, the depression turned to slowly rise, and some lakes shrank and became land. In the late Early Pleistocene, Muping Lake was connected with Yuanjiang depression, and the lake basin expanded. Chishan uplift became an isolated island between the two lakes. The lake water flowed into the Yangtze River from Nanxian County, nianshi city and Ouchi estuary, which was the most prosperous period of the lake in the Quaternary. As the lake basin turned to rise, the lake water retreated and the landscape of Dongting Lake Plain appeared. In the Middle Pleistocene, Dongting Lake basin developed into a lacustrine basin interwoven with river network, and the depositional systems of Lixian, Muping Lake and Yuanjiang Xiangyin. At this time, the lake water had two outlets, one from Junshan of Yueyang to the Yangtze River through guangxingzhou, the other from shejiatai of Anxiang to Jianghan basin through Lixian. In late Pleistocene, mupinghu depression and some areas of Yuanjiang Xiangyin depression were activated and subsided again, and Changde and Anxiang Hehu basins were formed in the west of Chishan, linzikou, huangmaozhou and Beida Hehu basins in the East, but other areas were greatly reduced and the shape was complex. The lake water flowed from south to North, and the East and west water systems confluenced near Tuanshan and flowed into the Yangtze River in Shishou area. In the late Holocene, the whole lake basin was the Dongting plain with crisscross river network. At that time, there was a small lake with a radius of 130 square kilometers in the south of Junshan.

After the pre Qin period, yunmengze gradually disintegrated and the relationship between the rivers and lakes changed, which directly affected the evolution of Dongting Lake. Since the Han and Jin Dynasties, the population of the Yangtze River Basin has increased gradually, the intensity of reclamation activities has increased, the natural vegetation has been destroyed, and the sediment concentration of the Yangtze River has begun to increase. With the gradual siltation of yunmengze in northern Jingjiang, the riverbed of Jingjiang River rises automatically, and the main channel of Jingjiang River gradually swings southward due to the influence of the northwest southeast neotectonic tilting movement. During the Yonghe period of the Eastern Jin Dynasty, Jingkou and lunkou were formed on the South Bank of Jingjiang River, and the water flowed into Dongting Lake. Because Dongting Lake receives the water and sediment from the two separate rivers, the deposition process of the lake begins to accelerate, forming Lake groups of different sizes. During the Tang and Song Dynasties, the formation of the unified riverbed of Jingjiang river changed the boundary conditions greatly. With the continuous construction of Jingjiang dike, the river surface is narrow and the flood discharge is not smooth, the flood level begins to rise, and the probability of river water jacking and backward irrigation increases. Whenever the flood passes through the Jingjiang section, a breach is often formed, and "nine holes and thirteen outlets" are formed. A large amount of flood from the Yangtze River was diverted from the mouth of the cave, which made the Dongting Lake expand obviously. The lake basin extended westward and southward, connected with Qingcao and Xitun Chisha in the south, and the water area expanded. The word "eight hundred Li Dongting", which describes the magnificent water of the lake, began to appear in the poetry books of this period. With the expansion of water area, Dongting Lake, Qingcao lake and Chisha lake, which were separated from each other in the Han and Jin Dynasties, were connected into a vast ocean at high water level. Due to the increasing influence of the Yangtze River, the flood process of Dongting Lake has also changed significantly. The flood process of Dongting Lake has gradually changed from "spring flood" to "summer and autumn flood" before Tang and Song dynasties. The flood characteristics of Dongting Lake have been highlighted except for the "peach blossom flood" injected by four rivers, which makes the flood process of Dongting Lake change from the original single peak in the year It was found that there were two peaks in the pattern.

After the Song Dynasty, the riverbed of Jingjiang River was silted up continuously, and the flood level continued to rise, which gradually changed the relationship between the lake and the river from "high lake and low river, lake water flowing into the river" to "high river and low lake, river water flowing into the lake" in the Wei and Jin Dynasties, and the flooding of Dongting Lake became more and more serious. During the yuan, Ming and Qing Dynasties, with the continuous construction of Jingjiang dyke and the stoppage of the cave, the river disaster intensified, and the dyke and Lake area of Jingjiang broke frequently. The relationship between the rivers and lakes began to tense, which shows that the relationship between the rivers and lakes began to change historically from the Song Dynasty, and human factors became the important factor of the variation of the relationship between the rivers and lakes.

After Jiajing of Ming Dynasty, the central government adopted the water control policy of "sacrificing the south to save the north". The North Bank of Jingjiang River was completely blocked, and the south bank was reserved with Taiping and tiaoxian, which connected with Dongting Lake. The Qing Dynasty continued to follow the Ming Dynasty's negative water control policy. With the increase of water from the Yangtze River, once there was a flood, the lake overflowed and expanded. The West Dongting Lake and the South Dongting Lake are gradually expanded under this background. During this period, the scope of Dongting Lake was "at the turn of summer and autumn, the lake overflowed, with a radius of 800-900 Li, while Longyang and Yuanjiang were in the southwest." It shows that Dongting Lake developed rapidly to the southwest after Xitun Chisha Lake in Tang and Song dynasties. Until the middle of the Qing Dynasty, Dongting Lake continued to expand. In the reign of Daoguang, Dongting Lake reached its peak since the pre Qin period. According to Daoguang's Dongting Lake annals, its scope is as follows: "the Northeast belongs to baling, the northwest spans Huarong, Shishou and Anxiang, the West connects Wuling, Longyang and Yuanjiang, the south belt Yiyang and the ring Xiangyin, where there are four prefectures and one state, and the boundary is divided into nine cities, spanning eight or nine hundred Li, where the sun and the moon appear and disappear." It can be seen that Dongting Lake has gradually "rejuvenated" since the Wei, Jin and southern and Northern Dynasties. From more than 500 Li in the Wei and Jin Dynasties to seven or eight hundred Li in the Tang and Song Dynasties, and then to eight or nine hundred Li in the middle of the Qing Dynasty, the lake waves can directly beat Yueyang, Huarong, Hanshou, Yuanjiang, Xiangyin and other counties. Junshan, Pengshan, Chenshan, Jishan, Tuanshan, leishishan, Chishan, Moshan and other islands in Wulihu. During the flood season, Dongting Lake covers an area of more than 6000 square kilometers.

In the middle of the 19th century, Dongting Lake began to change from prosperity to decline, and entered the most dramatic stage of evolution since records. It took more than 100 years for the lake to shrink from 6000 square kilometers to 2691 square kilometers. The main reason is the human and policy factors, leading to Xianfeng, Tongzhi

Chinese PinYin : Dong Ting Hu