2007-10-15 17:52:09 · 4 answers · asked by Anonymous in Science & Mathematics ➔ Earth Sciences & Geology
Geologically speaking:
Porosity is the ratio between the volume of voids and the total volume of the rock (how "porous" the rock is; how much pores account its totality).
Permeability, on the other hand, is the rate at which a liquid, such as water, passes through a void.
2007-10-16 01:32:31 · answer #1 · answered by bnj 3 · 1⤊ 0⤋
Porosity is the volume of void space in an object. Permeability is the ability for a fluid to move through an object. They're related, but not the same thing.
Think of it this way: A basketball has very high porosity because the only thing that's not air is the skin of the basketball, but it has no permeability, otherwise you'd have a flat basketball. Your cotton shirt has low porosity, but has permeability that can be seen by putting water in a fold of the shirt. The water will eventually move through the shirt.
2007-10-16 09:37:35 · answer #2 · answered by CSW 3 · 1⤊ 0⤋
All above are good answers, just wanted to add that you can have exactly the same porosity but vastly different permeability. Imagine two vertical tubes one packed with glass marbles the other with well rounded sand, the porosity is about 33% in each.(if you magnified the sand it would look just like the marbles) Now pour identical volume in the top of each cylinder, whats going to happen?, marbles almost 100% of the water will pour out the bottom instantly, sand: it might take a while and you will not recover all the water.
2007-10-16 10:13:11 · answer #3 · answered by cimra 7 · 1⤊ 0⤋
Porosity is the amount of space (void) between grains in a rock.
Permeability is the ability for fluids to move from pore to pore.
They are related but not the same thing. A porous rock can have low permeability. A permeable rock could have low porosity.
2007-10-16 00:54:54 · answer #4 · answered by Lady Geologist 7 · 1⤊ 0⤋