I don't think the scientific approach is as effective as an anthropological approach to legitimate the flood story.
Most world religions have a story of a massive flood, and while those stories from the ancient near east have similar characteristics (such as the Stories of Atrahasis, Gilgamesh, and the Flood Story in Genesis), most of the world's flood stories were created independantly of each other.
It is unclear as to whether they were all of the same time period (and I can easily agree that *some* of them could have been regional floods), but I can hardly discount all of them to regional floods.
While I do appreciate science, and studying how and to what extent the Flood took place, I think anthropology has more evidence.