11 In the six hundredth year of Noah’s life, in the second month, on the seventeenth day of the month, on that day all the fountains of the great deep burst open, and the floodgates of the sky were opened.
Genesis 7:11
So, like, most of the water probably came from underground, not from the rain. Though I'd imagine both were pretty bad.
Not saying the story is true or anything. Just pointing out the straw man, since the Bible doesn't claim all the water was from rain.
There's a number of places where Old Testament stories may actually be describing the stories of Bronze Age Libyans who end up relocated into the Southern Levant along with the sea peoples. Joseph with a colorful coat and an interpreter of dreams is sometimes likened to the Hyskos but compare the coat vs the depiction of the Libu. Not only are the Libu sporting blue in their coats, like the tekhelet later found in the OT, there's even the Tuareg Libyan people known for their blue dye and matriarchal lineage.
Around the time that tomb image is recorded there's even a papyrus talking about how the followers of Set have red hair and interpret dreams, and this is also the period when the Egyptian story "A Tale of Two Brothers" emerges with a number of similarities to the Joseph story.
This is interesting in light of the flood mythos because we now know that at the end of the ice age there was a migration down from Europe across the ice bridge to North Africa. This was around the time there really was coastal flooding including relatively rapid events which may have even persisted in local oral traditions.
Part of the issue with analysis of Biblical stories in terms of historicity (outside of the supernatural stuff) may be that we're analyzing a collection of stories that had been syncretized into a local tradition and later appropriated, much like the story of 'Israel' (Jacob) taking the birthright and blessing of Esau (the eponymous founder of Edom, meaning 'red') in the Bible.
In fact, according to the Dead Sea scroll fragment 4Q534 Noah had red hair.
So it need not even necessarily be that there was flooding in the Southern Levant for the flood mythos to be based on an oral tradition.
All that said, personally I'm rather persuaded by Idan Dershowitz's analysis that the Noah story was originally a story of drought and famine before syncretizing the Babylonian flood mythos into it later on and transforming it into a flood epic.
“At length, behold! there came our Command, and the fountains of the earth gushed forth.” — Holy Qur’an, 11:40
and
“O Earth! swallow up your water, and O Sky! withhold your rain! and the water abated and the matter was ended. The Ark rested on Mount Judi.” — Holy Qur’an, 11:44
No it isn't. Geology does not back up a global flood.
When it rains a lot and the ground gets saturated it can seem like the water is coming up from the ground. Also you know they had wells so they knew water is in ground.
Well aside from trapped water existing or not, this certainly didn’t happen. The geological layering of soil would tell us, the extinction events would tell us, and the fossils would tell us.
Not to mention there’s also a massive problem with heat and moving that much water so quickly.
It isn’t though. A worldwide flood would leave behind plenty of evidence in the geologic record. That it doesn’t exist makes it quite implausible. Making matters worse is the supposed time of the flood had many civilizations with extensive records for hundreds of years before and after forget to mention they were wiped out and instead just continued living through the flood without noticing it.
This relates to the bible concept of firmament, flat earth and separation of waters, as in genesis when it says god separated waters above and below.
The nomads knew wells, rain, islands, tides and flooding rivers, so the world they conceptualised was one where God moved water above and below to reveal dry land. As such in the story it seemed logically consistent to allow massive amounts of water to come from above and below returning the world in what they considered a previous, erased state to reboot it.