According to the Quran Noah was the only one who survived the FLOOD, then how did he multiply himself?

Nohe survived alone!! WHo told u that , i read that he & his followes built a huge ship & thos who belive in .God & his messenger .Nohe ride the ship with animals & survive but only one of his son didn't ride with his father saying that he'll clamb a mountain to protect himself from flood , he drouwened.