Jay, and Denial,
Yes that is roughly what I was asserting. When I say "everywhere" I mean it can happen anywhere that a watercourse is given some control by a major project such as damming. Then, land along the banks becomes more desirable for development (housing, industrial, commercial, whatever). That development inevitably changes shore slopes, runoff flows, and on the non-engineering side, the land value which influences political decisions.
Important to note that examples can be cited from any country you choose, and my country, Canada, is no exception. There's no desire to pick on China in what I say. It also happens in Brazil, USA, Germany, and so on. In 2013, much of the Highwood River flooding that ruined parts of the town of High-River Alberta (close to me) have been blamed on over-development of the flood plain and changes to the upstream slopes, which just channeled the slug of water toward the town faster and higher than it would have been with exactly the same amount of rain and runoff, if development wasn't there.
I'm not an environmental engineer so my understanding of the subject is weak. I just go by basic fluid dynamics and volume available to the river, which is what makes sense to me. A watershed with a slope of 100:1 being replaced by a 5 meter rockwall to carry a road will remove some cubic kilometers of volume that a flood could occupy. In my jurisdiction, all of this is hotly contested still, so the parts of the debate that pop up in mass media aren't always the most factual ones. It almost resembles the global-warming argument, as in "how could humans possibly cause an act of god such as a flood" while others have plenty of satellite and terrain maps showing exactly how, if only town officials would listen.