"God opened the windows of heaven".
So the water didn't all originate on Earth (according to Iona).

"Heavens" in this case means "Sky/Atmosphere". But the water didn't all come from the sky, as we see; "And all the fountains of the great deep were opened up"...This issue has been dealt with many times by reliable Creation scientists like the ones at ICR. I'm sure they have an article on it.
And, contrary to what was said earlier, I can reference Creationist scientists and still have my own beliefs. It just happens that I agree with them, just as you would agree and reference many evolutionary scientists. I don't have to have a PhD in order to debate, and it's perfectly acceptable for you or I to reference articles, quotes or whatnot that we agree with.

Iona
(Ps. I've heard that PhD is short for Permanent Head Damage, but I can't be sure of the truth of it)