Without believing every detail in the Genesis account, I think the Noah story plausible. Rather than undermining it, I would say that the Epic of Gilgamesh corroborates it.
Graham Hancock has spent a long time developing his theory that the Flood is a mythicised memory of the melting of the northern European ice sheets some 10,000 years ago. I recall reading somewhere that some Australian aboriginal tales may be as old as their first arrival to the continent, 40 or 60 thousand years ago. Why not? If a story can be passed down from one generation to another, why should the transmission cease, unless the tribe is destroyed by invaders?
I think - I speculate - that there may have been many Noahs. The ice sheets can't have melted in a single season, so quite possibly there was an annual flooding in warmer weather every year for very many years, and this could have stimulated men to learn to build larger and more robust ships, to keep their families and livestock safe, rather than canoes suitable for shoreline fishing. Perhaps this led to the colonisation of central America by oceangoing tribes, since I've read the hunters that came down the ice-free corridor through Canada didn't get that far.
Years ago, I bought my mother the Times Atlas of History, in which it stated that agriculture was invented in Anatolia, northern Turkey, which happens to be the area where the Tigris and the Euphrates rise (two of the rivers that flowed out of Eden). Agriculture and fishing, around the Pontian shore, a shore that would rise every year. And hasn't there been some evidence that there are indeed remains of man-made structures in the oxygen-starved mud in that sea-shelf?
Just because an old, old story doesn't agree in every point with current scientific theory, that doesn't mean it isn't essentially true; the Ark may or may not have been 300 cubits in length, yet it may still have been very big. And many people have noted how the account of Creation itself also comes close to accepted cosmological opinion.
It's like Schliemann and his discovery of the remains of Troy: we're so used to dismissing traditional stories that we may fail to be guided by them.