Originally posted by WPRESTO To be tiresome (getting better at it as I get older), what I used to point out to students in geology when discussing streams. There is a reason it is called a "flood plain." In fact, the flood plain is part of the channel of a stream, but the stream only uses when the discharge is uncommonly high. If there were a prolonged drought and a local stream went dry, would you sanction construction of houses in the dry stream bed? When you allow construction in a floodplain, that is precisely what you are doing.
A friend of mine explained this to me. I don't remember his argument exactly, but my take away message was that geologists define flood plane one way, but architects (?) and engineers (?) basically look at the recorded history and go from there. So if the place hasn't flooded in the last 50 years you are good to build there.
What's even more troubling is this. I remember listening to a woman who was was refused compensation for flooding in Alberta a couple of years ago because her house wasn't IN THE FLOOD PLANE. Only people in the flood plane got compensated for their stupidity.