Underwater reservoirs were most likely a factor, yes, but again, that was not the only source for the water. We see Texas rains--they can flood a place pretty fast. Multiply that by a hundred and you've got Noah's flood.

According to Creationist Literature which passed my way as a kid (and still holds some perverse fascination on me to this day) Pre-Flood Earth was a very different place: shallow seas, no mountains, one central land-mass and the earth contained within a thick sphere of liquid. Basically it was a steamy greenhouse - hot, humid, without rain; apparantly all this can be found in the Bible if you know where to look. When God brought the flood, He collapsed in the liquid sphere, flooding the entire planet and creating the seas we know today; after the flood, He tore apart the land-mass, sank the depths, raised up the mountains thus creating the more familiar landscapes pretty much overnight that Geologists insist are the product of billions of years of tectonic shift.

And what about the drogue stones of Noah's Ark that might still be seen in the Durupinar region?

I dare say all this is on-line if you've a mind to look for it.