The term survivor is commonly used to indicate people who lived through a traumatic event, even if the event wasn't fatal. It's like abuse survivors, they aren't saying they escaped death (in most cases) they are indicating they experienced something traumatic.
Maybe in the case of the floods it's a bit dramatic, but there are people who were legitimately traumatized by that event, so maybe it's accurate. Maybe we as a society need a more descriptive word, but this seems to be the one most commonly used.