So why become inconsistent with belief in the bible when it comes to the creation and flood account?
Well, as Coyote has said, it is because the flood story is demonstrably false. A literal interpretation (of whatever kind) is incompatible with reality.
Now, I know that you are going to disagree with that, so let me beg your indulgence here for a moment. What would you do if, hypothetically, you found a passage in the Bible that you could see was just wrong? I'm talking about a historical/factual type passage here, not one that is merely employing metaphor or poetry. What if you could see that the passage was simply at odds with reality?
Do you reinterpret the passage?
Do you regard the passage as being a human error, but maintain faith in a literal Bible in a more general sense?
Do you decide to treat the Bible as allegorical throughout, whatever the intentions of its authors?
Do you just cast it aside completely?
These are the kinds of questions that Christians (as well as Jews and Muslims) have been forced to confront over the years, as science and history have come into conflict with a literal interpretation of the text.
Mutate and Survive
"A curious aspect of the theory of evolution is that everybody thinks he understands it." - Jacques Monod