Upvote:2
When we talk about God's attributes we can't assume He has the same characteristics as the human beings, because we have mortal bodies, limited languages and understanding and a sinful nature, while God is infinite, has a 100% sinless nature, infinite understanding, etc. So, when the bible talks about God's changes of mind, is probably because the author (Moses, for instance) couldn't express in a better way what he was receiving from God, using a limited language as the Hebrew.
It is an interesting question anyway.
Upvote:2
Thomas Aquinas thoughts about God's nature, which was then adopted by Catholic Church, is that there exists a God's plan, which however is very general. A man can change his life, can do good or evil things, however he can't stop general God's plan. This is how free will is explained -- why would we need a free will if it is already determined what we will do?
I think that it is the same with the Flood. As Noah and his family had shown that they are able to follow God's plan, He "changed" His mind.
An interesting interview you can find here. One of the most important (for me) sayings is that we can't think about God and time together. So He can't change mind. Maybe, as Charlie said, it is just a word that the author put as it was the best in his culture.