The influence of the change of the Yellow River

Section 1 Changes of the Yellow River, the cradle of China culture

The Yellow River, like a golden dragon, lies across the northern land of the motherland. It has a total length of 5,464 kilometers and a drainage area of 752,443 square kilometers. The Yellow River Basin is the earliest birthplace of Chinese civilization, and the downstream area has been the political, economic and cultural center of China for a long historical period.

Second, immigrants from the lower reaches of the Yellow River.

Historically, the Yellow River is famous for its good siltation, determination and good luck. The changes in the lower reaches of the river are extremely complicated. From Jin Dream to Xingyang (South Bank) and Wuzhi (North Bank), because the river is constrained by the South Bank Mountains, it only moves very little in the direction from west to east. The ancient Golden Dream City is located at the north of today's city 12.5 kilometers, and the ancient Yellow River is even in the north of the ancient Golden Dream City. Now the Yellow River is only 2.5km away from Jin Meng, which indicates that this section of the river has moved southward by about10km. Below Wuzhi and Xingyang, the Yellow River officially entered the North China Plain and changed its direction on a large scale. The shunt is not only frequent, the flow path is disordered, but also the coverage is very wide. There are dozens of rivers in history, like the ribs of folding fans. Wuzhi and Xingyang are fan buttons, and the fan bones are distributed to Haihe River in the north and Huaihe River in the south. The diversion of the Yellow River has a great influence on the geomorphological changes in this vast area.

According to the literature, from the pre-Qin period to about 3000 years before liberation, the lower Yellow River burst 1593 times, with an average of two breaches in three years and 26 important diversions. Hu Weiwei, a beginner in Qing Dynasty, collated and summarized the records of thousands of diversions of the Yellow River in ancient times, and put forward five migration theories in Gong Yulue. After the fifth year of Xianfeng (1855), the copper tile compartments burst and diverted, and together with a migration, they were called "six major migrations". Coupled with the primitive old road before the early Warring States period, it can be summarized into seven stages. It is described as follows:

1. Rivers before the early Warring States Period

The "Yu He River" in the lower reaches of the ancient Yellow River, which people are familiar with in the pre-Qin literature, is also called "Gong Yuhe". According to the description in the chapter of "Gong Yu Water Diversion", it is "East Luoling, as for the big one; There is precipitation in the north, as for the mainland; It is also broadcast to the north as the Nine Rivers, and it goes against the water into the sea. " "Luoling" is the place where Luoshui flows into the river, and "Daxian" is in Xunxian County, Henan Province, which means that the ancient river flows northeast from the northern foot of Guangwu Mountain in Xingyang County, Henan Province to Xukou of Xigusu Mountain in the southwest of Xunxian County, and then travels north along the eastern foot of Taihang Mountain. "Precipitation" means taking water, and "mainland" refers to the mainland. It shows that the great river is in the south of quzhou county today, receiving Zhangshui from west to east, and then going north to Lu Ze. "Nine rivers" generally refers to the majority, which refers to the formation of the lower reaches of the Yellow River wandering in the central Hebei plain. "Against the River" is the backward flow of tidal water from the estuary, which enters the sea in the southeast of Tianjin today.

Another river in the lower reaches of the Yellow River in ancient times was found in the pre-Qin literature "Mountain Classics", which was ignored by the world because there was no record of river runoff in Mountain Classics. In recent years, Tan Qixiang found that after the Gong Yu River reached Shenxian County, Hebei Province, the "mountains and rivers" branched off and flowed northward, then merged with Tuotuo River, and then flowed northward to the south of Lixian County.

2. Rivers from the middle of the Warring States Period to the end of the Western Han Dynasty

The third river in the lower reaches of the Yellow River recorded in the literature is the river in Geography of Hanshu and Records of Hanshugou, that is, the "great river custom" in Notes on Shuijing River. Hu Weiwei said: "Five years ago (602 years ago), the river moved eastward from Xukou to Luochuan, to the right of Huatai City, to the south of Liyang County in the northeast, to Liangcheng County in the northeast, and to Changshou Jin in the northeast. So the river left Luochuan and entered the sea in the northeast. " The water mirror is called "the river is so blasphemous" and is considered to be the first diversion of the Yellow River after Dayu's flood control.

The specific runoff of this "big river" is as follows: the section above Suxukou, which is the same as the river course, flows from the northeast of Suxukou to Changshoujin (now northeast of hua county, Henan Province), which is described in detail by Hu Weiwei; After Changshoujin, the river flows northward, so far to the northeast of Guantao County, south of Gaotang County in east longitude, and then to the west of Dongguang County to meet Zhangshui, and then to the northeast through Hanzhangwu County (now Fuyi City in Huanghua County) and eastward into the sea.

Tan Qixiang's textual research shows that although it is not credible to say that this river started from the five-year migration of King Ding of Zhou, the formation of this "great river is so common" is likely to be earlier than that of Gong Yu and the rivers with mountain views. Long-term coexistence during the Spring and Autumn Period and the Warring States Period became the main. Around the 1940s, Qi, Zhao and Wei built dams on the east and west banks of the river for hundreds of miles respectively. After that, the rivers in Gong Yu and Shanjing were cut off, and the rivers in Han Zhi continued until the Han Dynasty.

In the mid-Warring States period, the lower reaches of the river were diked in an all-round way, which played the role of flood storage and sediment retention, so the riverbed was relatively fixed. Although it must have overflowed nine times, the most famous one is the third year of Han Yuanguang (before 132). "The river is determined by Zanzi (now southwest of Puyang, Henan Province), and it flows into Juye (now southwest of Shandong Province) in the southeast, connecting Huai and Si". This is the first time recorded in history that the Yellow River seized the Huaihe River and entered the sea. The flood "xian county 16th" (②) lasted for more than twenty years, and was not stopped until the second year of Yuanfeng (109). A few years later, most of the subsequent breaches were blocked and the river resumed its original route. This river has been stable for 475 years. However, at the end of the Western Han Dynasty, due to the long-term accumulation of sediment, "the river is higher than the flat land" and the major diversion is inevitable.

3. Rivers from the Eastern Han Dynasty to the Early Song Dynasty

Three years after the founding of the People's Republic (1 1), Wang Mang moved for the second time. "He Jue Wei County (governing powers, now southwest of Linzhang County, Hebei Province), several counties east of Pan Qinghe. First of all, the fear of the river in Yuancheng (now Daming East, Hebei Province) is definitely a deep disaster, and it is definitely eastward. Yuancheng doesn't worry about water, so it's not blocked. The western part of Shandong and the eastern part of Henan were flooded for nearly 60 years, until the twelfth year of Yongping in the Eastern Han Dynasty (69 years), when Wang Jing built a canal and embankment at the mouth of Xingyang East to Qiancheng (now northeast of gaoqing county, Shandong Province) (5), the great rivers in the Eastern Han Dynasty were formed, that is, the rivers recorded in the records of Zhu, Yuan and County in the Tang Dynasty.

The great river in the Eastern Han Dynasty lies to the east of the great river in the Western Han Dynasty. From Changshoujin, it bid farewell to the great river of the Western Han Dynasty, followed the Guluo River to the east, and then meandered between the Yellow River and Ma Jiahe, until now it entered the sea south of Binxian County. The distance from the sea is shorter than that of the great rivers in the Western Han Dynasty, and the rivers are relatively straight. After the Eastern Han Dynasty, the sediment concentration of rivers was relatively weakened. For these reasons, the river has been stable for more than 800 years, with no major changes, little overflow and no major diversion. Therefore, the history of Wei, Jin, Southern and Northern Dynasties failed to reach the Canal, and there is no record of the Yellow River in Geography of Sui Shu.

At the end of Tang Dynasty and the beginning of Song Dynasty, there were many breaches due to serious siltation and poor drainage in the downstream estuary. The most important one is that in the second year of Tang Jingfu (893), the Yellow River "went northeast from the county boundary, northwest of Bohai County (now Binxian County, Shandong Province), northeast to Wudi County (now Tongxian County) and eastward into the sea". In the first year of Song Jingyu (1034), the river broke through the Henglong River in Zhouyi (now Puyang East, Henan Province), and the next section of the river moved south to Changqing, forming Henglong River ②. However, the rivers below Changqing have not changed, only a small range of diversion.

4. Rivers after Li Qing in Northern Song Dynasty.

The eighth year of Li Qing in the Northern Song Dynasty (1048) witnessed the third great migration. The Yellow River burst at Lake Ku (now Puyang dongchang lake Collection) in Zhuozhou, then turned to the northwest, passed east of the Yellow River in Henan and west of Daming in Hebei, crossed between Fuyang River and South Canal, and flowed into Yu He (now South Canal) and crossed the boundary river (now Haihe River) along the east of Nangong, Zaoqiang, west of Wuyi, east of xian county and Qingxian. Song people called this river "Beiliu" or "Beipai".

Twelve years later, in the fifth year of Jiayou (1060), the Yellow River branched eastward in Wei County (now Nanlexi) of Daming Prefecture, and flowed northeast through a section of the old water channel of the Western Han Dynasty, from today's Tangyi and Xiajin in Shandong Province to Tuma River (now Ma Jiahe) and entered the sea between Hebei and Shandong. It is called Ergu River, and Song people call it "East Stream" or "East School".

Since then, sometimes the Yellow River flows singly, sometimes singly northward, and sometimes eastward and northward in parallel. Since the East River flows through the border of Hebei and Shandong, the river has been flooded and the terrain has been silted since the Han Dynasty. If the area west of the Yu He River is "the lowest place, the river will flow to the north by itself". At that time, there was a constant debate within the ruling class of the Song Dynasty about whether to maintain the Northern School or return to Dongjiang. The former advocated the maintenance of Beiliu in order to resist the invasion of Qidan with the help of the Yellow River. The latter "offered to open two shares and guide the eastward flow." Zongshen adopted the latter opinion and closed Beiliu in the second year of Xining (1069). But in the same year, the Yellow River burst in the south of the mouth. In the tenth year of Xining (1077), it broke through Ganzhou and merged into Liangshan Park. Then it is divided into two branches: one is called Nanqinghe from Si to Huai, and the other is called Beiqinghe from Hejian to Cangzhou. After several overflows, the old "north flow" was restored in the first year of Yuanfeng (108 1) and the second year of Fuyuan (1099) because the "east flow was high and the north flow was smooth". The route taken by the three northern streams is slightly different, either rushing into Zhangshui to the west or flooding into Yu He to the east. During the eighty years from the eighth year of Li Qing in the Southern Song Dynasty to the second year of Jian Yan (1 128), Beiliu was forcibly closed, forcing the single shareholder to flow, but it took 49 years for the single shareholder to flow northward, and it took 15 years, and the east, the west, the north and the south were parallel. Therefore, during this period, the mainstream of the Yellow River basically remained on the line running through the central Hebei plain to Tianjin entering the sea. It was this river that was recorded in the history of the Song Dynasty. During this period, due to the sediment of the Yellow River, "the river bed gradually silted up, and the ancient river belt flowing from the northeast to the Bohai Sea could not be maintained, so" the water potential moved south "was inevitable.

5. The river course from the fifth year of Ming Dynasty in Jin Zhangzong to the early years of Hongzhi.

In the fifth year of Ming Chang in Jin Zhangzong (1 194), the fourth great migration took place in Guanglu Village, Wu Yang (now Yuanyang County, Henan Province). According to Hu Weiwei's account: "The river moved eastward from Wu Yang, passing through Yanjin, Fengqiu, Changyuan, Yanglan, Dongming, Cao Zhou, Zhou Pu, Yuncheng and Fanxian, reaching Shouzhang and injecting Liang Shanlong. It is divided into two factions: the northern faction enters the sea from the North Qinghe River, and today the Daqinghe River passes through Dong 'e, Pingyin and Changqing from Dongping. Nanpai entered the Huaihe River from Nanqinghe, the old road of Surabaya. Today, Huitong River enters the Huaihe River from Dongping, Li Shen, Jiaxiang, Jining and Surabaya to Qinghe County. After the river was fixed, the Yellow River moved south and entered the old roads of Surabaya and Jishui respectively, forming a new school in the south and north. One-thirtieth of the river flows into the sea from the North Qinghe River (now the Yellow River), and one-eighth flows into the Huaihe River from the South Qinghe River (Surabaya). The water potential of the southern faction is greater than that of the northern faction, which is the beginning of the Yellow River's popularity in the southern hills of Shandong Province.

The Yellow River entered the Huaihe River not in the fifth year of Mingchang, but in the winter of the second year of Jianyan in the Southern Song Dynasty (1 128). Tokyo stayed in Duchong, above hua county, and crossed to the west (now Nansha Store, hua county, Henan Province), where it burst its banks to stop the nomads from going south, which caused a great diversion of the Yellow River and flowed eastward between Henan and Shandong in Juye and Jiaxiang, Shandong. In the sixth year of Jin Shizong Dading (1 166), in May, the river decided to Wu Yang, and from Yuncheng to the east, it merged into the water margin. (2) In the eighth year of Dading (1 168), in June, it "broke the water (now south of hua county, Henan Province) and drowned (now Heze, Shandong Province) and diverted to Shaanxi Province (now Shaanxi County, Shandong Province)." (3) From Cao and Dannan, Xu, Pi and Si entered Huai River. However, at that time, the "North Stream" of the Song Dynasty was not broken, and the Yellow River was still in the situation of north-south diversion. Speaking of "Jin Ming is in the middle and long term, the northern stream is lost, and it all enters the Huaihe River." (4) The Yellow River has never entered Hebei Plain for more than 600 years, which is a major change in the history of the Yellow River.

Five years before and after Jin Mingchang, the Yellow River trunk line also had a tendency to swing southward gradually. In the second year of Tiande (1 150), "the river flooded Juye County", and the main stream of the river moved from hua county and Puyang in northeast Henan to southwest Shandong; In the 19th year of Dading (1 179), "the river breaks the Bianliang River" (5), and the main stream turns south into Kaifeng House; In the 29th year of Dading (1 189), the river overflowed the north of Caozhou small dike, and the main stream has entered the territory of Guide House (now Shangqiu area). At the end of the Jin Dynasty, the Yellow River trunk line was roughly built, passed through Cao and Dan, and merged into the Huaihe River.

After the Yellow River entered the Huai River from Si, every time it decided to migrate, it was often divided into several streams, overlapping each other for the first time, and the river course was very chaotic. It is often seen that in the dry season, one tributary is dominant, while in the flood season, several tributaries are diverted from Huaihe River to Haiqi. In the Yuan Dynasty, three spillway channels, namely edge, vortex and ying, were formed on all previous crevasses. In the 11th year of Zheng Zheng (135 1), Jia Luzhi River, self-styled Huanglinggang River, led by the Yellow River, went out of Xuzhou. The so-called "river returning to the old road" is basically to restore the old road at the end of Jin Dynasty. Jaru blocked the estuary that flowed into the whirlpool and pond. But in this way, the Yellow River lost its vent path, only after fourteen years, and in twenty-five years (1365), it finally crossed Dongping and entered the Daqing River again.

In the Ming Dynasty, the Yellow River changed its course more frequently. On the main stream of the bypass road, when Yuanyang and Fengqiu burst, most of them rushed northward to Zhangqiu and carried the Qinghe River into the sea. In Zhengzhou and Kaifeng, when a breach occurred, many people seized the vortex in the south and entered the Huaihe River. However, the Yellow River in this period

For a long time, the main roads were still Kaifeng, Guide and Xuzhou.

6. The river from Zhongming to Qingxianfeng.

In the eighth year of Hongzhi in Ming Dynasty (1495), the Huangling Mountain was built, which was the fifth great migration of the Huaihe River.

In order to keep the Beijing-Hangzhou Grand Canal unblocked, the Ming government sent Liu Daxia, the deputy capital, to build seven ports, including Huangling Port and Jinglong Port. And built a long embankment on the north bank, starting from Qicheng, passing through Huaxian, Changyuan, Dongming, Cao and Shanxian, and reaching Yucheng, with a total length of 360 miles, called "Taihang Dike". Rebuild new dikes in Jinglong and other places. , starting from the north bank of Jiadian Xiangfu, passing through Tongwa Box and Chen Qiao, and arriving at Little songji in the Northeast (now songji in the northeast of Lankao), the distance is 160 Li. Make the Yellow River channel directly return to Dehua, Xuzhou and Suyu from Yanglan and Kaocheng, enter the canal in the south, and inject water into the sea in the east. With the construction of Huanglinggang and Taihang Dike, "the north flow will never be completed, and the water from the long river in Wan Li will be collected at the first line of Qingkou." (2) Hu Weiwei therefore regarded it as the fifth great change in the history of the Yellow River.

The purpose of river management in Hongzhi period was to prevent the north of the Yellow River from affecting water transport. The river regulation project is mainly to strengthen the north bank dike. The south bank was neither dammed nor blocked. Therefore, the diversion phenomenon of Sui, Vortex and Ying still occurs from time to time, which affects the water source of the main roads below Xuzhou. In order to ensure water transportation, in the 16th year (1537) and 21st year (1542) of Jiajing, water was diverted from Dingjiadoukou and Xiaofuqiao to the Yellow River and into Xuzhou trunk line to help Xu and Lu Erhong. After the diversion outlet on the south bank was blocked, after twenty-five years of Jiajing (1546), "Nanxi old road began to be blocked". So "the river is full of promise, swish, and it has been taken into the Huai River". Since then, the Yellow River has become the only access to the sea.

After the Yellow River trunk highway was repaired, the riverbed became a "suspended river" above the ground due to long-term sediment deposition. Floods are becoming more and more frequent. In the late Jiajing period, the breach was mostly in the area from Cao Xian to Xuzhou. After arriving in Qin Long, it developed from Xuzhou to Huaiyin. Therefore, the focus of the river regulation project has always been "not in Shandong, Henan and Abundance, but in Xuhe and Pi" (5). Pan Jixun, the left assistant minister of the Ministry of Industry, according to the policy of "attacking sand with water" and "storing clear water to brush the Yellow River", completed the river regulation works of Yao Di on both sides of the Yellow River and Gaojiayan levee east of Hongze Lake in the seventh year of Wanli (1579), also in this reach. Its old river course is roughly the blocked Yellow River on today's map.

After entering the Qing Dynasty. As a result of the long-term implementation of "binding water to attack sand", a large amount of sediment is discharged into the estuary, "so that the water flow slows down, the sediment stops and the estuary accumulates day by day." (1) Since the 16th year of Kangxi (1677), the key point of Jinfu River regulation is Huaiyin to Hekou. He took the policy of dredging as the main task, from the steps of Qingjiang River to Haikou, and dug deep into the riverbed by "picking ditches". But it only works for a while. After a long time, the bottom of the river silted up. After Jiaqing, the situation of political darkness, lax river management and overflow of crevasses is increasing day by day, especially the sand bed deposition at the lower reaches of the river and the Huaihe River into the sea is more serious, resulting in the situation of "above-ground water flowing upward". The Yellow River and Huaihe River themselves have to give up this downstream channel with poor water flow and find another way.

7. The river course after five years of Qing Xianfeng.

In June of the fifth year of Xianfeng in Qing Dynasty (1855), the Yellow River burst in the Tongwafang house in Yanglan (near Lankao, Henan Province), crossed the canal in Zhangqiu Town, Shouzhang County, Shandong Province, and carried the Daqing River into the sea. This was the sixth great migration.

At the beginning of the breach, it was flooded in Fengqiu, Xiangfu, Lanyi, Kaocheng, Changyuan and other counties, and then it was "divided into three shares: one was released by Zhaowanghe in the south of Caozhou Prefecture, Shandong Province, and the other two shares were released by the north and south gates of Dongming County, Zhili, passing through Fanxian County, Zhou Pu, Shandong Province to Zhangqiu Town, and finally returning to Daqing River". Since then, the lower Yellow River has ended its 660-year history of entering the sea from the Huaihe River and returned to the situation of entering the sea from the Bohai Sea. At that time, Weng Tonghe and Li Hongzhang represented the interests of the landlord class in Anhui and Jiangsu, and they disagreed with the gag. Ding Baozhen, the governor of Shandong Province, on behalf of the Shandong landlord class, demanded that this matter be settled. The two sides argued endlessly, and the Qing government faced the storm of the Taiping Heavenly Kingdom revolution. "military affairs have no time to take care of river workers." Therefore, in the past 20 years, the flood was allowed to flood in the southwest of Shandong Province until the first year of Guangxu (1875), and the whole river was built from Daqing River to the sea, forming the lower reaches of the Yellow River today.

From the formation of the lower reaches of the Yellow River today to more than 70 years before liberation, the river floods continued year after year, from 1855 to 1938, and the breach reached 124 times. Sometimes it invaded Tuhai River in the north and Xiaoqing River in the south. In the seventh year of Tongzhi (1868), the river burst in Yingze Fangzhuang, and in the thirteenth year of Guangxu (65438+), there were two major breaches in this century: one was the catastrophic flood in 1933, which caused great disasters in 52 places within more than 200 kilometers from wen county to Changyuan; Once, 1938, the Kuomintang government blew up the Huayuankou levee in Zhengzhou to prevent the Japanese army from advancing westward, and the river was chaotic and whirlpool into the Huaihe River, resulting in a nine-year diversion. By March 1947, the mouth was blocked and the old course of the Yellow River was restored.

Historically, the change of the lower reaches of the Yellow River, the general trend is that crevasses change direction more and more frequently. Except for the first and second great migrations, there were few forced migrations for hundreds of years, and there was a long period of stability. After the diversion of Li Qing and Mingchang, there is not even a river that has been fixed for 30 years. After the diversion of Hongzhi, several streams of water still coexist, and the flow direction is disordered, and the mainstream changes from time to time. In order to "protect the Yellow River", the rulers of Ming and Qing dynasties did not hesitate to violate the nature of the river and forcibly "the whole river flows out of Xu, Pi and Si into Huai", but in the end they had to return to Bohai Bay to enter the sea. Throughout the historical period, the change and evolution process of the lower Yellow River is extremely complicated, and what Hu Weiwei did only represents the general trend of its change. In recent years, Zou Yilin put forward four stages according to the main flow direction of rivers: from the Bohai Sea before the Song Dynasty, from several streams to the sea after the Jin and Yuan Dynasties, from one stream to the sea after Jiajing in the Ming Dynasty, to Lijin in Shandong after Xianfeng in the Qing Dynasty. It is more concise and quite unique.

The diversion of the Yellow River is mainly in the lower reaches, but there are also diversions in the upper and middle reaches. The upper reaches mainly occur in the back of Hetao Plain. According to the Water Mirror Notes, this river "crosses the west of Linrong County in Shuofang in the north, ... and flows to the north, so it turns into the South River. This river flows to the north and west, and overflows to the east of the old town of Maohun County ... Its water accumulation is deep and lustrous, making things a hundred miles away. " This river "succumbed to the northeast flow direction of (Lin Rong) County, and ... became the North River". "The river in the south of East Gaojing Que ... north of the old city of He Lin County" (2). It shows that Wujiahe, a tributary of the Yellow River north of Houtao, was called "North River" in ancient times. It is the positive flow of the Yellow River, but now the river course is called "South River", which is a tributary. Therefore, Zhu called Beijiang a "big river". The place in the Qin and Han Dynasties was later called "Henan Land". Until the early Qing Dynasty, the mouth of the Beihe River was gradually silted up. Tu Shenze near the estuary (because it is in the east of Maohun County, also known as Maohunze, later renamed Tengger Caspian Sea) was silted up into a sand pile due to the eastward movement of the Yellow River, and the North River gradually narrowed into a distributary "Wujiahe" (Wujiahe), and the main stream of the Yellow River began to be diverted to the South River.

As for the middle reaches of the Yellow River meandering between Shaanxi and Shanxi, some areas are swaying from side to side due to floods. For example, in the Ming Dynasty (1465- 1487), the river originally located in the south of Dajinguan (formerly known as Linjinguan) on the west bank of the Yellow River was diverted to the west, turning Luoshui (1), which had "entered Wei" since ancient times, into a river. During the Wanli period (1573- 16 19), a section of the river north of Grand Customs Clearance also changed to flow westward, reaching Chaoyi County, where Grand Customs Clearance was separated from Hedong. During the Xianfeng period of the Qing Dynasty (1851-1861), the southern section of the Qing Dynasty turned eastward again, and Luoshui became the Weihe River again. In the twentieth year of Guangxu (1894), Luoshui was heavy and heavy because of this.

Throw it into the river. 1934 flood, the river turned eastward, Luoshui entered the Weihe River again, and the customs clearance was restored to Hexi position.

Three. Causes and effects of diversion of the lower Yellow River

Soil, climate and the slope of the Yellow River are the natural factors that cause frequent migration and diversion of the lower Yellow River. The middle and upper reaches of the Yellow River flow through the Loess Plateau with an area of 580,000 square kilometers. Loess structure is loose. Once washed away by rain, the soil will go with the water, and the sediment content in the water is extremely high. At the same time, the precipitation in the Yellow River basin is mostly concentrated at the turn of summer and autumn. After the rainstorm in the middle and upper reaches, there will be flood peaks in the riverbed, and both flood and sediment will pose a serious threat to the downstream. In addition, the upper reaches of the Yellow River originated at an altitude of more than 3,000 meters, ran down from Longyang Gorge in Qinghai, ran for thousands of miles, reached the east of Mengxian County in Henan Province, and suddenly reached the plain below 50 meters above sea level. The flow rate slowed down, the sediment sank and gradually silted up. According to the measured data in recent years, the sediment transported to the lower reaches of the Yellow River reaches1600 million tons every year. There are about twelve of them.

Hundreds of millions of tons were transported to the sea and 400 million tons were deposited on the river bed. Over time, the river bed was lifted higher and higher, becoming a "hanging river". Generally, the riverbed is two to ten meters above the ground, and there are dams on both sides of the river. Once it is broken, it will rush to fill and diarrhea, and it will be out of control. Therefore, the Yellow River has been known as "good at silting, settling and moving" since ancient times.

Judging from the migration and diversion of the Yellow River in the whole historical period, the dividing line can be 10 century. In the two thousand years before that, there were two major diversions, and there were few other migration records. The Yellow River is basically stable and calm. This is because the forests and grasslands in the plateau areas in the middle and upper reaches of the ancient Yellow River are still relatively complete. For example, Rushan Canyon and the upper reaches of Jingwei Beiluo are basically animal husbandry areas, and the virgin forests and grasslands have not been destroyed. In the more than 3,000 years before the Tang Dynasty, the average temperature was 2℃ higher than it is now, which was also conducive to the growth of vegetation. This good vegetation condition is enough to keep water and soil. In the middle and lower reaches of the valley plain, the ancients dug countless irrigation canals and ditches on both sides of the Yellow River, among which Wei introduced Zhang Shui to irrigate leaves, Qin introduced Luo, and Han Wudi introduced Jing to Wei. Historical Records Biography of Rivers and Channels said that irrigation canals were "trillion" at that time, and these canals and ditches introduced the sediment carried by river water into farmland as fertilizer. In addition, the famous rivers such as Hebei, Bian, Pu and Luo in the lower reaches of the ancient Yellow River, as well as spider webs, Tianjin, and spread.