Fortunately, we're on a ridge, but a lot of fancy mansions were built too close to Peachtree Creek which has a fairly large watershed. Guess what happens in heavy rains?
The Chattahoochee is mostly hemmed in with bluffs, no real bottomlands around here to build anything, so the river stayed relatively pristine except Lake Lanier.
The Ohio River cuts through bluffs but does have some bottomlands along the path, many of which today are heavy industry. I remember flying our little Cessna up the river a bit, it was pretty neat to see all this stuff along the river.
Well, at least Americans know better than to build a large city somewhere in the middle of a desert. That would be inane. How would they get water?