read the recent findings about the Bosphorus, the Dardanelles, the Black Sea and earthquake induced floods....here and at other sites.(a google search on bosphorus + dardanelles + noah will give you LOTS of ideas about how such a story could have gotten famous.

Archeology may yet solve many of the historical confusions about how a flood could seem "world wide"...if your world is small, and everything you see is under water, but YOU survived on a shed roof with a few animals...you might embroider the story a bit, too...