According to modern research, the worst-hit area of prehistoric floods should be the lower reaches of the Yellow River, which is the most important place for Dayu to control water. Legend has it that Dayu demarcated Kyushu in Yanzhou, which makes sense.
The word "Yan" in Yanzhou comes from Yanshui. Yanshui, also known as Jishui, is one of the four blasphemies in ancient times. In ancient times, saving water was very important. The ancients called rivers with independent sources that could enter the sea "blasphemy".
The four blasphemies mentioned in Erya: Jiang, He, Huai and Ji, are four rivers that flowed into the sea alone in ancient times, and "Ji" means saving water. Jiyuan in Henan, Jining in Shandong, Jiyang and Jinan are all named after Jishui.
Jishui originated from Taiyi Pool in Wuwang, Jiyuan City, Henan Province. Jishui flows through Henan Province and Shandong Province into the sea. With the passage of history and the change of landforms, Jishui was blocked by drought in the Wangmang period of the Eastern Han Dynasty, and Tang Gaozong resumed its opening and drought. The Yellow River changed its course many times, invaded south, and gradually rushed into the Jishui river bed and into the sea.
In the lower reaches of the Yellow River, Daqing River (formerly Dongping Lake to the Yellow River Estuary) and Xiaoqing River (a small river that flows into the Yellow River from Dongxihu in Dong 'e Town, called Xiaoqing River) are the old roads of Yuanji Water.
The Yellow River is famous for its "good siltation, good decision and good luck", and it is said that it will burst twice every three years and change its course once in a hundred years. According to statistics, in the thousands of years before 1946, the Yellow River burst 1593 times and changed its course 26 times. The northernmost branch flows through the Haihe River, leaving Dagukou; The southernmost point passes through the Huaihe River and enters the Yangtze River.
The accumulation landform formed by sediment carried by the Yellow River is the fundamental reason for the breach. 1855 before the Yellow River burst, Wei Yuan found that the terrain on both sides of the Yellow River was high in the south and low in the north, and thought it was inevitable that the Yellow River burst in the north. Whether there is sediment in the Yellow River does not depend entirely on human unreasonable economic activities.
Beach siltation in flood season, river siltation in dry season and long-term river bed uplift. The Yellow River has less water and more sediment, and the serious imbalance between water and sediment is the crux of the Yellow River problem. During the 2600 years since Zhou Ding's five years, the lower reaches of the Yellow River experienced a great cycle of swinging from north to south and from south to north.
There are countless breakthroughs and shifts. Generally speaking, Jin Meng is the apex, and it is the diversion and migration range of the Yellow River on such a large delta as Tianjin in the north and Huaihe River in the south.