Specific
Capacity: Specific capacity of a well is
the rate of flow from a well per unit of drawdown. It should be determined for
the fall of the first meter, as it is not the same for all the drawdowns.
Coefficient
of Storage or Storage Coefficient or Specific Storage or Storativity (S): In general, storage coefficient (S) is
defined as the volume of water that
an aquifer releases or stores per unit surface area per unit decline or rise of water table.
Where, S = Storage
Coefficient
yw = unit weight of water
H = confine aquifer thickness
1/Es = compressibility of aquifer, where Es = elasticity of aquifer
1/Ew = compressibility of water, where Ew = elasticity of water = 2.1 x 10-6 KN/m3 at 10°C
yw = unit weight of water
H = confine aquifer thickness
1/Es = compressibility of aquifer, where Es = elasticity of aquifer
1/Ew = compressibility of water, where Ew = elasticity of water = 2.1 x 10-6 KN/m3 at 10°C
Typical
Values of Elasticity (Es) of Aquifer Material
Sl. No.
|
Aquifer
Material
|
Elasticity (Es)
|
1.
|
Loose sand
|
104 to 2 x 104
|
2.
|
Dense sand
|
5 x 104 to 8 x 104
|
3.
|
Dense sandy gravel
|
105 to 2 x 105
|
4.
|
Loose clay
|
103 to 5 x 103
|
5.
|
Stiff clay
|
104 to 105
|
