The calculation of water is likely based on the water needed to cover present mountains. We do not know that the high mountains of today existed. That means possibly a lot less water was needed. Your question is where the water came from (that is known) and where did it go. In my creationist perspective I think that most of the water that covered the earth came from the other side of the firmament. (the firmament is where the stars were made) In creation week waters were separated below and above this firmament, and in the flood portals of heaven were opened allowing those waters beyond where stars are, to be transported to earth. Science envisions wormholes. That might give some small idea of what kind of higher science was involved here. The waters seem to have come across space and time through windows of heaven!
There is no limit as to how much water could come this way.
The fountains of the deep closed. A great wind came. In a hundred and fifty days the waters had receded. I suspect that those windows of heaven stopped bring rain, and maybe started 'sucking' it back up! That explains where the water went and came from. Science is not able to understand these things. That is why there is no scientific explanation.
Science has limits. What lies beyond the known and limits of natural science may seem strange to those pegged to those limits. But by the tone of your posts it seems you don't care and have a religion to defend.
The huge door of the ark was closed by God. The animals called to the ark by God. The waters were sent and taken away by God. There is no natural (where natural is defined by ignoring and omitting all parts of nature that are not physical) explanation possible.
For all we know, it could have been a fountain of the deep that is no longer active in Yucatan that may have shot stuff upward. (impact from below). You could be misreading evidence. Now if you can prove otherwise, fine. Your little statements have zero value as anything other than statements of faith meanwhile though, of course.
So, impact, yes! Impact around the time of the dino demise, yes.
Walt Brown envisioned a great and forceful reuption of the fountains of the deep that ejected stuff violently upward. He even imagined that much of it went into space it was so forceful. Now we do not know the force involved, but it seems a safe bet to assume that the direction of the event may have come from below. Science has assumed it must have been from above. Got anything more than assumptions? Yes we have impacted quartz, but does it show direction?