Underground, several ancient city pools in Kaifeng were deeply silted up by the flood of the Yellow River and buried underground. On the ground, the riverbed is constantly rising due to the sediment deposition of the Yellow River, forming a "suspended river on the ground" where the river is higher than the city. Both landscapes are wonders of the world and appear in one city at the same time. "Looking at the history of Kaifeng City for more than 3,000 years, its rise and fall are inseparable from the word' river'." Qiu Gang, a researcher who has been engaged in archaeological research for a long time in Kaifeng, said.

1. The mother river gave birth to "overlapping cities"

Walking on the famous Liuyuankou Yellow River levee about 0/0 km north of Kaifeng, you can clearly see that the water of the Yellow River is 3 to 5 meters higher than the ground on both sides. The Yellow River in the north of the levee is running, and the villages, trees and farmland in the south of the levee seem to have fallen into the pit. Even tall poplars are not as high as levees.

According to experts, Kaifeng belongs to the middle and lower reaches of the Yellow River Basin. The Yellow River crosses the world's largest Loess Plateau and enters the vast North China Plain. The terrain is flat and the flow rate is slow, and the huge amount of sediment brought from the middle and upper reaches has been deposited. This phenomenon is most obvious in Kaifeng. According to statistics, 300 million tons of sediment is deposited in the downstream riverbed every year, which makes the riverbed rise by 10 cm on average every year. This kind of accumulation, year after year, makes Kaifeng River gradually form a world-famous "hanging river" spectacle. In the history books of the Qing Dynasty, it is recorded that Kaifeng City is "at the bottom of the kettle, looking at the Yellow River ..."

The flood threat of the Yellow River has always been the most serious downstream, reaching Tianjin in the north and Jianghuai in the south. On the fan-shaped plain of 250,000 square kilometers, the traces left by the overflow and diversion of the Yellow River for more than 2,000 years can be seen almost everywhere, directly causing several ancient city pools in Kaifeng to be deeply deposited underground. According to archaeological excavations, Weidaliangcheng, the lowest city in Kaifeng, is now more than 10 meters underground. Bianzhou City was about 10 meter deep from the ground in Tang Dynasty, 8 meters deep in Tokyo City in Northern Song Dynasty, 6 meters deep in Bianjing City, 5-6 meters deep in Kaifeng City in Ming Dynasty and 3 meters deep in Kaifeng City in Qing Dynasty.

Kaifeng was chosen as the capital because it is close to the Yellow River.

"Water can carry a boat, but it can also overturn it". When discussing the reasons for the formation of Kaifeng wonders, experts summed up the rise and fall of Kaifeng for thousands of years in one sentence, that is: success is also the Yellow River, and defeat is also the Yellow River.

It is understood that Kaifeng, as a city, the first glorious period in history was Dewey Daliang City in the Warring States Period. At that time, Wei Huiwang was the first to choose Kaifeng as its capital, which was related to the fact that the area was not far from the Yellow River and Jishui, and there were four waterways. Soon after he moved to Daliangcheng, he organized a lot of manpower to dig an artificial canal nearby, which is a famous gap in history. However, it is precisely because of this gap that the Great Liangcheng was destroyed.

In the war to unify the six countries in the Qin Dynasty, the two countries fought fiercely at the gates of Daliang. Unable to attack for a long time, Qin Jun poured water into the girder through the Yellow River diversion gap. After three months of water encirclement, the bustling girder city was reduced to ruins. This is also the first time that Kaifeng has been hit by floods.

The Bianhe River, which evolved from the gap, became an important part of the Beijing-Hangzhou Grand Canal. A very important reason why the Northern Song Dynasty, which was in its heyday in Kaifeng's development history, built its capital here is also the word "river", that is, the reason of Bianhe. At this time, the Bianhe River has become a major channel connecting north and south traffic, which has brought unprecedented prosperity to Kaifeng.

It is also the Yellow River that hurts Kaifeng.

The Yellow River flooded for 2000 years, flooding several cities in Kaifeng. This is a popular saying. It is generally believed that these ancient cities were ruthlessly submerged by the sediment of the Yellow River because of the flood of the Yellow River. However, in the process of gradually uncovering the phenomenon of "overlapping cities" in Kaifeng underground, relevant experts corrected this understanding.

According to Qiu Gang, director of Kaifeng Cultural Relics Department, before the Northern Song Dynasty, the Yellow River flowed through the northern part of Henan Province and entered the sea from Tianjin, hundreds of miles away from Kaifeng. Although it has been overflowing, it has no direct impact on Kaifeng. The Yellow River really began to threaten Kaifeng's safety after the Yellow River diverted south in the Jin Dynasty.

During the following 1000 years, the Yellow River burst more than 300 times, of which 7 times were flooded into the city. According to historical records, the Yellow River burst in 1305, completely flooding Kaifeng City. 1642, in order to retreat from the peasant army in Li Zicheng, the Ming army dug the Yellow River levee. "The city is flooded from the inside, and the people you see are just the second floor of the bell and drum, the roof of Fan Qun Temple, the top of Suoguo Temple and Zhou Dicheng." The tall Kaifeng city wall is almost flat, with only battlements and parapets exposed. After the flood, there were only 20,000 people left out of 370,000 people, and Kaifeng City suffered heavy losses.

The Yellow River was swallowed up again and again, and wind, sand and fire invaded. As a big city in the Northern Song Dynasty, Tokyo City (former site) was gradually completely buried by sand and disappeared from the ground. Because of the Yellow River, Kaifeng fell from the capital to the provincial capital, and then to the prefecture-level city, and gradually declined.

However, it is precisely because of the "big quilt" of the Yellow River that Tokyo and other places can be protected from more wars, fires and sandstorms, preserved and presented with rich cultural heritage. Every time I think about this, many experts and scholars often sigh: destroying the Yellow River is also the Yellow River.

■ Expert comments

Professor Zhu, an expert in historical geography:

Kaifeng City is a history of dynastic changes.

With the efforts of archaeologists, the mystery of Kaifeng's "city on the city" spectacle has been unveiled layer by layer, and this unique phenomenon has also aroused widespread interest from all walks of life and close attention from academic circles.

Professor Zhu, a well-known expert in historical geography and president of China Ancient Capital Society, is very excited: the phenomenon of "adding cities to cities" has been recorded in the literature for a long time, but there is no archaeological material to prove it. Without the means of archaeological work, it is difficult to reveal the remains of "one city after another" clearly and accurately as it is today.

He said that due to the unique hydrological characteristics of the Yellow River, many towns in the Yellow River Basin suffered the same fate as Kaifeng City, but Kaifeng was the Seven Dynasties, which is unique in the history of China's 5,000-year civilization, world archaeology and capital city.

Professor Zhu also spoke highly of the academic research value of the phenomenon of "cities overlapping cities". He said that the five cities are superimposed on each other, showing the history of the ancient city changes for more than 2,000 years since Kaifeng was founded. To some extent, a Kaifeng city is also a history of dynasty change. Qiu Gang, a researcher in Kaifeng City:

The concentration of "overlapping cities" fluctuates along the Yellow River cities.

For Qiu Gang, director and researcher of Kaifeng Cultural Relics Department who has been engaged in archaeological excavation in the ancient capital for 20 years, the formation of the phenomenon of "overlapping cities" is closely related to the Yellow River, the mother river of the Chinese nation. The rise, development and decline of the Yellow River in ancient China, as well as its influence on the reproduction of the Chinese nation and the formation and development of Chinese culture, are vividly and concretely concentrated in another sense of "overlapping cities", which provides a lot of materials for studying the floods, siltation and disasters of the Yellow River. Cheng Minsheng, Professor of History Department of Henan University:

Kaifeng is the representative of indomitable spirit.

Cheng Minsheng, a professor at the School of History and Culture of Henan University, said that the six floors of Kaifeng City are stacked, especially since the Tang Dynasty, and the central axis of the city has not changed for more than 2,000 years. It is a typical representative of indomitable spirit and a miracle in the history of world civilization.

Cheng Minsheng also said that Weidaliang City, the first capital city in Kaifeng history, was completely submerged and should be preserved more completely than Tokyo City now discovered. If one day it can be discovered by more advanced archaeological means, the phenomenon of "overlapping cities" will be more important in academic research.

Jinghua Times (version A09, February 8, 2002)