This megaflood wasn't in historic times; writing systems of some sort may have been in use, but there's no way to read them, or even know what langauge may have been spoken at the time in the location. Furthermore, the sudden release of meltwater was first identified in the 1930s; it took a long time for the opponents of the idea to die off, but in the 1980s or so, the guy who identified the Channeled Scablands flood event was honored.
IOW, this has nothing to do with the Noachian Deluge.
In her Plato Prehistorian: 10,000 to 5000 B.C. Myth, Religion, Archaeology, Mary Settegast reproduces a table which shows four runic character sets; a is Upper Paleolithic (found among the cave paintings), b is Indus Valley script, c is Greek (western branch), and d is the Scandinavian runic alphabet.
