Global Flood vs Local Flood
There are two views concerning the Great Flood, one is that the whole world was flooded and the other is that only a part of the world was flooded.
If we consider that Noah represented the 10th generation from Adam, a local flood may well indeed have been enough to cover the entire inhabited earth.
Just a thought.
I believe that this may have been the case as with similar world-wide events such as the famine predicted by Joseph.
Genesis 41:57 "Moreover, people of all the earth came to Egypt to buy from Joseph, because the famine had a strong grip on all the earth.
Bare in mind that Joseph is 14 generations from Noah, how much of the world would have been repopulated since the finish of the flood?
Just another thought.