Uh, I was gonna say. Humans practice agriculture around rivers because they flood, fill the area with rich silt and organic matter. Nile delta anyone?
Got a couple of acres of swamp down in Florida. Fascinating seeing this on a microscale. From my tent and north, we got 1-3" of crappy topsoil. Heavy thatch of roots, then sand and some clay. Go 10' south and its rich, black silt, the real sticky icky. 10-seconds with a trowel, you know what's up, where you're at.
Hell, the flora changes within 50-100', just look up. Pine and oak to the north, cypress and the like to the south. Doesn't take a masters in ecology to see the lay of the land.
"Let's build shit here! Look how rich the soil is, surely if will never flood right next to a river!"
I am disappoint at the engineers who didn't make those bridges taller. C'mon guys.
