My visits to Coastal and Central China over the years revealed to me the topography of the country. It seems hilly all over and has little of the great mostly flat farming belt of the USA.
As a consequence, it is ripe for flooding as rainwater collects massively between the hills and furiously travels down to the rivers before the land soaks it in.
Any prolonged rainfall like they appear to be experiencing exacerbates flooding.
This is a big issue for China to handle as its big cities along the rivers have a lot of its commerce.