obviously the porosity percentage of clay soil is relatively more than sand, but clay is impermeable /seal. what I know is the porous the geologic material the is higher its porosity will be. so how do you convince this confusion me please?
Permeability is more than only porosity. To illustrate this you can take the simplified case of porous media consisting of identical parallel tubes. In that case the permeability equals phi*r^2/8 (phi=porosity, r=pore radius). You can derive this result with the help of the Haagen-Pouiseuille model for flow through a tube. What this equation tells you is that the permeability strongly depends on the pore radius. So, besides looking to the porosity of medium (soil), you should also determine the pore size distribution. To a first order, you could try to measure the specific surface area.
Note that in flow problems you often assume no-slip conditions at surfaces.. That is the source for friction. The more surface per volume (the smaller the pore size), the lower permeability you expect.
Less numbers of pores would cause reduction in hydraulic conductivity of soils.
you are perfect! but, the porosity of a sack of Teff (clay) is higher than a sock of been (sand ) but, if you allow water to pass through in which material could water freely pass through? and why?
Water will freely pass through sand. The effective porosity of a substance facilitates the transmission of fluid. It is the measure of interconnected pores. There are these two absolute porosity and effective porosity. According to me the effective porosity of clay must be less than that of sand. There has to be some research article mentioning about this effective porosity amd absolute porosity of sand/sandy soil and clay/clayey soil.
Dear Mulusew,
The reason is due to the size, sorting, and interconnectedness of the grains found in the porous media of Geological mateials.
Porosity of a soil is the function of chance of having pores for permeability and hydraulic conductivity means porosity is the first concept from which these later words are derived... porosity means pore space..
100%= pore space%+ solid space%
Solid space is bulk density/ particle density
Bulk density= weight of soil solids/ volumn of soil
Partical density= weight of soil solids/ volume of soil solids
(Bulk density/partical density)×100= volume of soil solids/ volume of soil= solid space
Means porosity is (1-BD/PD)× 100, shows the pore space present in the soil to permeate water through soil means permeability is the function or outcome of porosity...
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