[ndt]

"There have been floods for eons, right? What happened to that water?"

Those are local events and amount in a shift of existing water from one point to another. For example, in New Orleans, water evaporated from the ocean and fell as rain; additionally, a swell of water moved from the ocean to the land; both instances resulted in the shifting of existing water.

A world wide flood requires the appearance and disappearance of enormous quantities of water.

[mlc9852]

The oceans are pretty big.