Odd that you use that term. Being from Kansas, I would have thought you’d noticed how farmers dealt with fences that need to cross creeks and such. I guess not. But as you’ll notice in this link, flood gates tend to be wide and rather short. The gates in the border wall are tall and narrow. Just like you’d use for humans to pass through. Flood gates also have the hinges on top, human doors or gates have hinges on the side.
https://lefence.com/specialty-fences/water-gap-fencing-solutions/
Common sense ain’t so common, is it Bob.