Ok. Change the word plain to zone.
We have ‘mountain’ property bordering the Nantahala National Forest. We’ve seen what heavy/fast rains can do, even create temporary spectacular waterfalls.
Point is, we’d never put human-built structures in those areas at risk from rising and fast flowing waters. These folks lost everything amd its tragic.
I've rafted the Colorado thru Marble canyon a morning after some evening rain.
Muddy waterfalls leaping from cliffs hundreds of feet high are quite an amazing things to see.