I will stipulate that there may have been some sort of localized flood that inspired the ANE flood mythology, and that the Noahic flood myth is based upon that.
While the Black Sea deluge may seem like a likely candidate, there doesn't seem to be enough solid evidence to really support that hypothesis at this time. I am more inclined to think that the ANE flood mythology is based on something that happened in the region of the Tigris and Euphrates.
While flood stories exist throughout the world and I want to point out the flood mythologies are not universal, and where either the stories and/or mythologies exist there is very liitle in common. There is, I think, no evidence for a universal flood mythology.
A universal, global flood of the proportions described in Genesis is not possible nor is there evidence for it.
The Noahic flood is most likely a story that was borrowed from ANE culture and subverted for specific theological purposes.