Regarding the flood narrative

This question has been bothering me, and I can’t seem to ever get an actual answer. In Genesis 9:11, God states that he will never again wipe out all of mankind with a flood (the seemingly only notable exception being Noah and his family). The real problem comes from the fact that we don’t have evidence for a global flood. But there still would be the option to view the events of the Flood as local. But again, there are floods far more devastating then the biblical flood (if it was a local one). Whenever the flood account is supposed to take place, human populations would have been very small compared to today or even other region, such as China, where singular floods have probably killed more. So what is the answer to this? I can’t seem to figure it out.