The great flood debunked by math

An other fairytale is the story of  Noah's ark 

There is absolutely NO evidence of a global flood but even without archaeological proof is can be debunked by doing the math.

Just let us make a crude calculation:(in the metric system)

The total surface of a sphere is 4πR²
We know the circumference of the earth is 40,000  Km
The radius of the earth = 40,000 : π : 2 = ±6366 Km
That makes the surface 4 x π x 6366 x 6366 = ±509.000.000 Km²
To keep it simple the highest point of the earth, Mount Everest, is 8000m = 8Km
We know the earth has 1400000000 Km³ of water and has been constant for the pas billion years..
http://www.unwater.org/statistics_res.html
To flood the earth you need 8 x 509.000.000 Km³ = 4.072.000.000 Km³ of EXTRA water on top of the 14 billion Km³ water the earth already had..
Suppose heavy rains give 100cm a day in rain fall so 8000 meters of rain would take 8000 days and nights of rain and that is 21.9 years..
Again it is a crude calculation, I can be off 10% but it is still a ridiculous amount of water..
And think of this: So much extra clear water added to the sea would have killed 99% of the ocean life ..

OK this raises a few new questions :

#1 where did all this water come from ??
#2 Where did it go to after the flood ?

Answer, it is impossible, the great flood is a myth...