China has the longest history of severe flooding of any nation. The Yellow River is called “China’s Sorrow” because of its tendency to change its course when it feels the urge. Sometimes the course changes have devastated whole provinces.
In old China a herculean effort was made to build the canal systems to try and contain the floods, with considerable success, but the river was never really tamed. The river also directly affects the traditional, fertile grain growing regions of China. It provides the water and the nutrients, in normal flow, but in flood it destroys them. Flood and famine were often linked in Chinese history.
So “unprecedented” flooding does have a pedigree as a term to describe the present massive deluges which are affecting half of China. The rainfall is extremely heavy, but happening erratically, and bizarrely the actual total rainfall for Beijing is slightly below average this year.
Economic damage will be difficult to assess until after the flooding. There are reports of damage to infrastructure and crops, and it’s estimated that over 3 million people have been displaced.