It was first seen in the ancient book The Book of Songs: History of Rivers, Hanshu and Southern History.
The Yangtze River is 6300 kilometers long.
The average annual flow into the sea reaches one trillion cubic meters, which is twenty times that of the Yellow River.
There are more than 700 tributaries, with a total basin area of1800,000 square kilometers.
It has a long history, abundant water, numerous tributaries and vast river basins, ranking first among the major rivers in China.
Since ancient times, the Yangtze River basin has been one of the important areas of political, economic and cultural development in China.
Throughout the historical period, great changes have taken place in the Yangtze River.
I. Formation of the Yangtze River
According to the ancient legend of China, Yu's water control "cuts off the river and leads to nine roads".
It is said that people from Wenchuan County, Sichuan Province once dredged the Minjiang River in Tiebaoling area of Wenchuan County. And "definitely Wushan, make the river cross the east" (4).
He also said that he had been to Tushan, Anhui Province and Huiji, Zhejiang Province to manage the water system in the middle and lower reaches of the Yangtze River, and finally made the Yangtze River "the land where the five lakes flowed eastward to benefit Jingchu and Nanyi" (5).
Another legend is that at the beginning of the Warring States Period in the 5th century BC, there was a man named Aoling in Jing. His body died, and he went up with the river and survived.
Meeting with each other, taking Aoling as a phase, Yushan emerges from the water, and Yao Ruo is flooded, which can't be cured, so that Aoling decides Yushan and the people's security is granted by the state.
Aoling acceded to the throne, posthumous title enlightened emperor. "
⑥ Li Daoyuan's Notes on Water Classics records: "Wushan Gorge is narrow, and the Shu River does not flow, and the Emperor makes it (Aoling).
Dig the water of Wuxia Gorge and get the land of Shu.
Looking forward to the emperor's self-reliance and morality, taking national Zen, it is called enlightenment.
All landowners these myths and legends about Dayu's flood control, Ming Chengzu's opening of Lei Yu and martial arts just reflect the strong desire of the ancient working people in the long-term flood control struggle.
The Three Gorges of the Yangtze River is obviously not the result of artificial excavation or ghosts and gods, but the result of natural evolution.
The ancient Yangtze River can be traced back to the Triassic period 200 million years ago. At that time, the terrain in central Chinese mainland was high in the east and low in the west. Now it belongs to the west of Wuxia Gorge and Xiling Gorge in the Yangtze River valley, and it is a part of Wang Yang's boundless ancient Mediterranean.
It is also a huge bay connecting the Indian Ocean and the Pacific Ocean.
About 1 100 million years ago, due to the strong orogeny, Hengduan Mountain and Qinling Uplift were formed in Mesozoic Jurassic. The ancient Mediterranean withdrew from today's Sichuan, Qinghai, Guizhou and western Guangxi, forming a huge Sichuan basin between Qinling, Hengduan Mountains and Yunnan-Guizhou Plateau. At that time, Dongting River Basin, east of Wuxia and Xiling Gorge, became a self-contained internal water system.
Wushan Mountain Range has also become the watershed between Sichuan Basin and Dongting Basin.
About 70 million years ago, at the end of Mesozoic, there was a Yanshan movement, in which the Sichuan Basin rose and the Dongting Basin fell. The ancient Yangtze River in western Hubei began to develop and actively extended to Sichuan Basin. About 30 million to 40 million years ago, the Himalayan orogeny caused the ground of the whole basin to rise intermittently, and the upstream rose most sharply, forming mountains, plateaus and canyons. The middle and lower reaches rose slightly, and hills and mountains appeared, accompanied by intermittent sinking, forming Shui Yuan of Hunan, Hubei, Nanxiang, Poyang, Jiangsu and Anhui.
At the same time, the Book of Songs? Xiaoya? April.
2 Huai Nan Zi? Outline ".
3 Historical Records? Xia Benji? Justice.
4 High temptation: "Huainanzi? Repair "precautions.
(5) "Mozi? Fraternity
⑥ Quoted from Yan Kejun in Qing Dynasty: "Ancient three generations, Qin and Han Dynasties, Three Kingdoms and Six Dynasties".
All landowners "water by note" volume 33 "river note".
In the past, the ancient Yangtze River traced back to Sichuan Basin was connected with the water system of Sichuan Basin. Because of the high terrain in the west and the low terrain in the east, when I watched the long river roll forward, it merged into a big river flowing eastward. This is the process of the formation of the Yangtze River before mankind entered the historical period.
Second, the exploration of Jiangyuan in past dynasties.
In the pre-Qin period, Jialing River, a tributary of the Yangtze River, was regarded as the upstream source of the Yangtze River.
"History? Gong Yu has "Minshan River Diversion" and? According to Gu Jiegang's textual research, the so-called Minshan Mountain in ancient times was not the Minshan Mountain in Songpan, Sichuan, but the birthplace of Jialing River, located in the southwest of Tianshui County, Gansu Province 120? Zhushan 1.
Hanshu? "Geography" has a record of "long time out" (2).
Han Sui has been in Naxi Autonomous County of Lijiang, Yunnan Province for a long time. Rope water is Jinsha River, but it was not clear at that time that it was the source of the Yangtze River.
In the Tang Dynasty, the Han people had close contacts with the clans, and they already knew the Tongtian River, where traffic must pass, but their relationship with the source of the Yangtze River was still unclear.
Xu Xiake, a famous geographer in the late Ming Dynasty, wrote Tracing to the Source (a study of the source of the river) after a practical investigation of the Jinsha River, which corrected the wrong understanding that the source of the river was in Fujian.
It is pointed out that Jinsha River originates from and is the positive source of the Yangtze River.
From the forty-seventh year to the fifty-seventh year of Kangxi in the Qing Dynasty (1708- 17 18), the map of the inner hall of Kangxi was actually drawn, and the Muluwusu River (i.e. Tongtian River) was drawn.
Later, Qi pointed out in Jiang Dao Bian: "Jinsha River is the ancient Lishui River, also known as Suoshui, also known as the river. It was once named Mulu Wusu, at the eastern foot of Bashatong Lamu Mountain in the Wei Dynasty. The mountain shape is as tall as an ox, that is, the ancient Lishi Mountain. "
Note: "Twenty-five degrees and four minutes west longitude, extremely thirty-four degrees and six minutes west of the source of the Yellow River, there is a Butun Chu River, also known as Bachu River".
During the Ming and Qing Dynasties, the names of Niulishi, Shilishan or Bashatonglum Mountain were called Dangla Mountain, also known as Wu Chao Lashan, and Dangla was a transliteration of Tanggula.
The Blachu River or Bachu River is the source of the Yangtze River.
Jiang Dao Bian not only points out that the Yangtze River is located in the Tanggula Mountain area west of the source of the Yellow River, but also mentions the Ketuonai Wulanmulun River (Tuotuo River), Kaqi Wulanmulun River (Gaerqu) and Akdag Muhe River (Dangqu River), which describes the source water system quite comprehensively.
However, due to the limitation of production level and scientific activities at that time, it was impossible to find out which of these sources was the positive source of the Yangtze River.
Because the source of the Yangtze River is steep, the air is extremely thin, the climate is changeable, it is inaccessible, and the path is difficult to find. Under the restriction of objective conditions at that time, a unified and correct understanding of the source of the Yangtze River has never been reached. Until the early liberation, the fallacy that the Yangtze River originated at the southern foot of Bayan Kara was still prevalent.
In order to find out the situation of the Yangtze River and make better use of its water resources, the Yangtze River Basin Planning Office organized two river source surveys 1976 and 1978, and confirmed that the real source of the Yangtze River was the detachment of the southwest side of Ladan Winter Snow Mountain at an altitude of 662 1 m on the Qinghai-Tibet Plateau (or Toto River), which was also mentioned in Qi's "Riverside".
In Tanggula Mountain, a continuous snow mountain group, there are dozens of modern canyon glaciers. Melting water and rain and snow springs of these snow-capped mountains converge into Gaerqu, Buqu and Dangqu in the east of Gladin's winter snow. * * * together constitute the source water system of the Yangtze River. They converge from south to north along the east of Tuotuo River, forming a fan-shaped river network in the upper reaches of Tongtian River, flowing to an altitude of 4,500 meters.
(2) hanshu volume 28 geographically.
(3) Qi: Jiang Daobian, "Little Fang Hu Zhai Yu Cong Chao", No.4. ..
In fact, Tongtianhe flows eastward to the west of Qumalai, accepts the Chumar River, which originated at the eastern foot of Hoh Xil, and continues to flow southeast, crossing the Batang estuary of Yushu, which is the Jinsha River.
Among the five major rivers in the Jiangyuan area, namely, Chuma River, Tuotuo River, Gaerqu, Buqu and Dangqu, Tuotuo River is the longest, reaching 358 kilometers. According to the principle of "the source of the river is only far away", Tuotuo is the main stream of the Yangtze River, but Dangqu is only one kilometer shorter than Tuotuo, with a drainage area of 302 19 square kilometers, while Chumar River is 20,909 square kilometers. The flow of Dangqu River is 220.58 cubic meters per second, which is five or six times larger than that of Tuotuo River.
Based on the distance from the source of the Yangtze River, the size of the flow, the width of the basin and other factors, it seems that the source of the upper reaches of the Yangtze River should include Jacky Tuotuo River, Nanyuan Dangqu River and Beiyuan Chumar River, which is more acceptable.
Third, the evolution of the middle and lower reaches of the Yangtze River in historical period.
The upper reaches of the Yangtze River in the west of Yichang, Hubei Province, flows between mountains and valleys, and the riverbed is relatively stable in historical period, with no obvious changes.
Below Yichang, the Yangtze River came out of the mountain and entered the vast and flat plain area in the middle and lower reaches, and the riverbed changed greatly in the historical period.
In the early history, the climate in the Yangtze River basin was warm and humid, with dense forest vegetation, wide and shallow riverbeds in the middle and lower reaches of the Yangtze River and numerous distributary channels.
Jianghan Plain, where Guyun Mengze is located, is a delta plain with Jiangling as its apex. During the Spring and Autumn Period and the Warring States Period, distributary channels such as summer water and gushing water developed. On the plain of the lake delta where Gupeng Lize is located, starting from Wuxue (now Guangji, Hubei), Shangshu? Gong Yu's so-called "empty drinking in Jiujiang" is also a description of the diversion of some rivers in this reach during the Warring States Period.
Later, Sima Qian's "Looking at Jiujiang in Yu Shu from Mount Lushan" showed that the distributary channel still existed in the Western Han Dynasty, and the distributary relics of the Yangtze River with Wu point as "* * *" were still faintly discernible in satellite and aerial photos.
With the development of the Yangtze River, the distributary channel to the north of the Yangtze River tends to die out.
Since then, the riverbed in the middle and lower reaches of the Yangtze River has evolved into two different models in the following two sections due to the differences in landforms:
1. Changes of Jingjiang meandering river
Jingjiang River starts from Zhijiang and ends at Chenglingji, with a total length of about 400 kilometers. It is the most typical section of the Yangtze River bed evolution in historical period.
Among them, the Shangjing River, which is about 180 km long from Zhijiang to Ouchikou, is relatively stable because the structural movement of the riverbed is consistent with the flow direction, which enhances the longitudinal velocity of the river and the cementation degree of the sediments on the riverbank is relatively tight. However, at the exit of Dongting Lake in Hunan Province, there is a "Xiajingjiang" with a length of about 240 kilometers from below the Ouchikou to Chenglingji. Its flow direction intersects vertically, and the transverse circulation has obvious scouring effect. The sediments on the shore are also loose and easy to be hollowed out by running water, so it gradually developed into a typical "free meandering" in historical period, that is, a meandering river.
Its tortuosity coefficient reaches 2.0 1-3.57, and it is called "nine-bend ileum".
The channel of the ancient Jingjiang River is submerged in the lake where the ancient Yunmengze is located in Jianghan Plain, and the riverbed shape is not obvious. Jingjiang River is still in the overflow stage.
During the Qin and Han Dynasties, due to the long-term siltation of the Yangtze River, the Jingjiang Delta with Jiangling as its apex developed eastward and southward in Yunmengze, and some distributary channels began to appear in the lower Jingjiang River, which was in a highly limnetic stage.
Wei, Jin, Southern and Northern Dynasties, according to "Water Mirror? According to Jiang Shuizhu, the riverbed of Jingjiang River under Shishou has begun to form, and there are many sandbars in the river, which have developed into a tributary. In the Tang and Song Dynasties, with the disappearance of Yunmengze in Jianli County, the unified riverbed of Jingjiang River finally took shape. At that time, there were more than 20 rivers on both sides of the river, and there were pumping, summer water and crane water diversion in Hebei, which played a regulating role in the flow of Xiajing River.
The history book says: "Before the Song Dynasty, the acupoints were unblocked, so the river course was less affected.
"It can be seen that the riverbed was relatively stable at that time.
① Yangtze River Basin Planning Office and Jingjiang River Bed Experimental Station: River bed evolution and analysis of Jingkou revetment reach, 1975.
In the Southern Song Dynasty, when the Jin people occupied the north, the Han people moved south on a large scale, built dikes along the river, expanded reclamation, and the two sides were almost completely blocked.
The dam prevented the river from overflowing to the floodplain during the flood season and restricted the water flow to the riverbed. Because of the large amount of sediment deposition, the river bed is raised and the flood process is obvious, it is almost inevitable to break the dam.
In the seventh year of Dade in Yuan Dynasty (1303), the customs resumed at four o'clock in Song Dynasty, Tiao County and Chiba.
Temporarily reduced the threat of floods.
In the Ming Dynasty, these * * * were wiped out again.
During the period of Qin Long (1567- 1572), the hole of the suspension line was dredged, but it was not enough to reduce the change of flow only by this hole.
When the water flows through the bend, due to the centrifugal effect, the concave bank gradually collapses and retreats under the scouring of the mainstream, while the sediment is deposited on the convex bank with slow water flow, and the bend gradually stretches.
In this way, Xiajing River adapts to the increased flow by increasing the length of meander.
In addition, people built dikes on the newly deposited sandy beach on the convex bank of the meandering river for reclamation, which further strengthened the riverbed on the convex bank.
The original single straight line type soon became a meandering river type.
Zhao Nan's Waterway Outline in the Qing Dynasty said: In the late Ming and early Qing Dynasty, Xiajing River "started from Jianli to Baling (Yueyang), and began to merge with Dongting and Northeast China at the zigzag place", which shows that Free River Bend has been highly developed.
During the Tongzhi period of the Qing Dynasty (1862- 1874), there was only one Hudukou in Xiajing River without siltation, and the artificial dikes on both sides of the river developed on a large scale, and the sandbars of Lianjiang River were also enclosed in the dikes.
The length of meandering belt increases sharply, and with the increase of meandering, the bending radius becomes smaller and smaller, and finally a gourd-shaped river ring is formed.
In the flood season with steep slope, under the long-term action of floodplain water, the narrow neck beach surface gradually forms a chord hook. When encountering a big flood, the string hook is washed away and becomes a new river, resulting in natural bending.
According to incomplete statistics, natural bending has occurred more than ten times in the last hundred years, among which Moon Lake (1886), Ancient Long Dike (1887), Huangni■ (1906), Chiyakou (1909) and Drum are the most famous.
Due to natural bending, the length of the lower Jingjiang bend is greatly shortened.
However, under the action of water flow, the new river bed after cutting and bending began a new process of bending.
After liberation, at 1967 and 1969, artificial bending and straightening works were carried out on the two bending sections of Xiajing River, Zhongzhouzi and Shangchengwan.
In addition, in 1972, natural bending occurred on the beach in Jianli county, and the river channel bending coefficient decreased from 3. 19 in/949 to 2.02②.
In total, the length of the river channel is shortened by 80 kilometers, and the flood discharge is increased by about 5,000 seconds cubic meters, which has played a certain role in flood control and navigation.
In the early historical period, there were many distributary channels on the north bank, and the alluvial plain north of Xiajing River had been silted up. In addition, the rising speed of the north bank is higher than that of the south bank. Under the terrain of high in the north and low in the south, most of the bends in the Lower Jingjiang River occur at the southern end of the bend, forcing the main channel to swing to the right bank, with the maximum migration range of 10 to 20 kilometers.
2. Changes of bifurcated rivers below Chenglingji
The Yangtze River is about 1 160 kilometers long from Chenglingji to Jiangyin estuary. It flows on the vast accumulation plain of hilly terraces, with vertical and horizontal tributaries and developed bends, and belongs to a low-degree branching river.
In this reach, the common bedrock on both sides of the river stands by the river, and the cliffs are like obstacles, which are called "rock walls".
From Chenglingji near Yueyang, Hunan, to Huanglingji and Chenjiaji in Hubei, Penglang and Madang in Pengze, Jiangxi, Taizi in Zongyang, Anhui, Cai Shijie in Maanshan, Reading Historical Records, Volume 78, Huguangsi in Shishou County, Jingzhou Prefecture.
(1) Sun: Changes in the Middle and Lower Reaches of the Yangtze River in Historical Period, Science Bulletin, Vol.28, No.2 1983.
(1) Pan Qingshen et al.: Study on the evolution of artificial bends in the middle reaches of the Yangtze River, China Science, No.2, 1978.
② According to the June CCT band of Landsat in the United States 1978+00,10/computer image processing photos.
There are more than 120 rocky places in the northern suburb of Nanjing, such as Yanziji.
Plus Chibi in Puyin, Yuyue in Jiayu, Snake Mountain in Wuchang, Guanyin Stone in Sun Yicheng, Shi Zhongshan in Hukou and Lion Mountain in Nanjing.
These hills and rocks are a kind of fault fracture zone in geology, and the Yangtze River bed develops along these fracture zones, which restricts the possibility of its complete free swing.
So it can't wander and migrate freely on the endless alluvial plain like the Yellow River.
The riverbed is often very narrow at the outcrop of the rock head. After crossing the rock head, the riverbed widens, forming a coupling knot with alternating width and width.
According to historical records, these hills and rocks have been near the great river for a long time, and the riverbank has been relatively stable, which determines the general flow direction of the Yangtze River in historical period.
The formation of the low-branched channel in the lower reaches of Jingjiang River is determined by its geological and geomorphological conditions and hydrological characteristics.
From the former point of view, it is precisely because there are many nodes on both sides of the Yangtze River, the riverbed is wide and narrow, and the water flow is urgent and slow; From the latter point of view, rivers carry more sediment.
According to the statistics of 1953- 1972, the average sediment concentration in Hankou for many years is 0.6 16 kg/m3.
Close to Loki, the river bed is narrow and the water is fast, which has the function of attacking sand with water. Out of the rocky area, the river bed is wide and the water velocity drops sharply, which often leads to siltation in the Jiang Xinzhou and bifurcation of the river.
At present, there are more than 20 Jiang Xinzhou 120 branches and more than 0/00 branches in the Yangtze River from Xiajing River to the estuary, with a total length of 650 kilometers, accounting for 56% of the total length.
In ancient times, when our ancestors mainly lived in the Yellow River valley, the Yangtze River was wide and deep, and there were few records about the Jiang Xinzhou of the Yangtze River in historical materials before Qin and Han Dynasties.
Since then, the Yangtze River basin has been gradually developed. Due to vegetation destruction, soil erosion and sediment increase, more sandbar records have appeared in the Yangtze River.
The formation of the Jiang Xinzhou of the Yangtze River is not only closely related to the bifurcation of the river.
When the current rises, the river overflows the beach, which leads to the change of the direction of the hydrodynamic axis, which also causes the Jiang Xinzhou.
They restrict and transform each other, and the ups and downs of Jiang Xinzhou and the fork road are still frequent in the historical period.
Under different conditions, it generally shows the following process: (1) On the loose silty river bank, the riverbed widens due to the scouring of the river, and the Jiang Xinzhou deposits, which leads to the development of the entrance.
For example, Nanmenzhou in Xindi reach of Honghu Lake in Hubei Province, Baishazhou in Jiayu reach, and the upper and lower sandbars in Pengze, Jiangxi Province are all single-channel rivers.
Since19th century, under the lateral erosion of the river, the river has widened, and the Jiang Xinzhou has silted up, leading to the bifurcation of the river.
Siltation in Jiang Xinzhou promotes the strengthening of lateral circulation, thus accelerating the collapse of river banks and the widening of river channels.
(2) At the bend stage, the Jiang Xinzhou was formed because the flood cut the beach.
For example, Yejiazhou under Luo Zhen Town, Dongyang, Wuhan, Hubei Province, is the "eventful continent in the Northern Dynasties" mentioned by Li Daoyuan in the Notes on Water Classics in the Northern Wei Dynasty.
The scattered flower island on the other side of the river in Huangshi City was named after "Wu Zhu scattered flowers here" during the Three Kingdoms period, according to the "Illustration of the Yangtze River".
Xiaogushan, Pengze, Jiangxi Province, according to historical records, the county seat is ten miles north, thirty feet high, and one mile in Fiona Fang, where the lonely peak is steep, once half-way into the river, and now stands in the river.
"(2) the long sandstorm near Anqing, Reading Historical Records also records Anqing's" five miles east of the government, also known as Changfeng clip, waterfront river "(3).
These ancient branches and ancient Jiang Xinzhou, which were formed by cutting the beach, were eroded and integrated with the river bank due to the change of river hydrodynamic force.
But in recent years, from aerial photos or satellite photos, we can clearly see the remnants of beach cutting.
(3) Due to the swing of the main channel, the tributary channels gradually silted up, leading to the merger of Jiang Xinzhou.
For example, Water Mirror ① Department of Water Resources, Ministry of Water and Electricity: Statistics of Hydrological Characteristics of Major Rivers in China, 1975.
(1) (4) Notes on Water Classics (Volume 35) Notes on River Water.
(2) Reading Historical Records Volume 85, Jiangxi III, Jiujiang House? Pengze county.
(3) Reading Historical Records Volume 26, Jiangnan Volume 8, Anqing House? Huaining county.
Note "records that near Jiangxia (now Wuchang)," the right bank of the river is the south of Nautilus Island "(④). In the Tang and Song Dynasties, Nautilus Island was two miles away from the southwest bank of Wuchang (5). Later, the illustrated "Yangtze River" recorded that during the Hongwu period of the Ming Dynasty (1368- 1399), tidal sand was filled up.
During the Qianlong period of the Qing Dynasty, a new Nautilus Island was deposited near Hanyang, which no longer exists.
Another example is Muluozhou outside the mouth of Poyang Lake, which was formed after the Han Dynasty. In the Song Dynasty, there was still Muluozhou in Dehua County (now Jiujiang)
The record of "⑥" in the fifteen miles of Northeast China.
By the end of the Ming Dynasty, when the bank collapsed, the picture of the Yangtze River said, "Lintan ancient mulberry land is also". Another example is that in the Three Kingdoms period, there was Egret Island at the foot of Liang Qingshan in Nanjing, but not in the Yuan and Ming Dynasties.
(4) The original smaller Jiang Xinzhou merged into a large Jiang Xinzhou, thus reducing the air intake and enhancing the stability.
For example, Nanjing is now along the Yangtze River Bridge. From the Three Kingdoms to the Southern and Northern Dynasties, there were Ma Zhou Ang and Xinzhou in the river.
During the Sui and Tang Dynasties, in addition to Ma Zhou Ang, there were Luzhou and Xinzhou were also divided into upper and lower Xinzhou.
During the Yuan and Ming Dynasties, there were Caoxiezhou, Daoshizhou and Huguozhou.
In the late Ming Dynasty and early Qing Dynasty, it was Caoxiezhou, Baguazhou, Qilizhou and Dahesha.
At the end of Qing Dynasty, these Jiang Xinzhou gradually connected and aggregated into a goose-head-shaped Baguazhou.
Branches have also been reduced, and Baguazhou has been in a relatively stable state since then.
(5) Due to the instability of the main channel of the river, the growth and decline of the branch channel and Jiang Xinzhou also have the characteristics of alternating evolution, which is manifested in the deposition of another new Jiang Xinzhou after the disappearance of the old Jiang Xinzhou.
This alternate evolution sometimes presents periodic changes.
For example, Guanzhou, near Huangshiji, southwest of Anqing, in the eighth year of Qing Xianfeng (1858), the main channel of the river grew eastward and southward, with a length of 7800 meters. Before 1934, the main channel turned to the south branch, and the southeast coast of Guanzhou continued to erode and retreat, leaving only one-eighth of the original area.
After taking measures to protect Guanzhou from bank collapse, the riverbank stabilized and gradually connected with Peiwenzhou, forming a goose-headed Jiang Xinzhou.
In the south, Zhou Xuewen is also newly silted and gradually developed into a vast street clearing island, thus forming a compound gooseneck-shaped bifurcated reach.
In the historical period, the banks of Jiang Xinzhou in the reach below Jingjiang River of the Yangtze River mostly moved closer to the left bank, and rarely moved closer to the right bank.
It always cuts with the natural bend of Xiajing River on the right bank, forcing the main channel of the Yangtze River to move south.
This general trend of migration from the left bank to the right bank has formed a pattern of more wide beaches on the left bank and more rocky heads on the right bank.
Except for the ebb and flow of the Jiang Xinzhou and its tributaries, most of the water in the middle and lower reaches of the Yangtze River flows on the vast floodplain and loose riverbanks. With the change of the main channel and the scouring of the river, there are many records of bank collapse in history. Most of these bank collapses occurred in the river bank below Jiujiang, such as Xuba in Tongling, Anhui (1506- 18). Jiangdu ancient city in Yangzhou collapsed into the river during the Three Kingdoms period, and Guazhou city collapsed into the river in the 10th year of Guangxu (1884), and its banks collapsed on a large scale, engulfing a large number of farmland and towns.
The siltation of the beach by the river made the original wharf abandoned and the ferry moved; The rise and fall of sandbars will affect the passage of navigation channels.
Studying the historical changes and laws of the Yangtze River is of great significance to the comprehensive improvement of the Yangtze River in the future.