Permeability is ability of water to seep or percolate through interconnected voids.
The table shows permeability of different soils
|
Soil |
Gravel |
Sand |
Silt |
Clay |
|
Permeability |
10-1
to 101 |
10-1
to 10-3 |
10-3
to 10-5 |
10-5
to 10-7 |
The permeability of clay is 10-5 - 10-7 -Least permeable
This is mainly due lack of large interconnected voids.
It is clear from the figure that gravel has large interconnected void spaces.
Water can easily pass through these voids.
This space gets reduced as we move towards clay.
- Due to the lack of these interconnected voids water takes more time to percolate.
- The adsorbed layer in Clay also plays an important role in reducing the permeability.
This is the major reason why clay is less permeable.
Also, the shape constant of clay is very low compared to other soil. This is another recent why clay is impermeable
Also because of this behavior clay usually acts as an Aquitard impeding the flow of water.
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