1. The coefficient of permeability of the two soil layers 1 and 2 in soil deposit is 9*10-7 cm/s and 4*10-7 cm/s respectively. The thickness of the layers is equal. The value of average permeability parallel to bedding planes is ________
a) 4.5*10-7 cm/s
b) 5.5*10-7 cm/s
c) 6.5*10-7 cm/s
d) 7.5*10-7 cm/s
Explanation: Given,
K1=9*10-7 cm/s
K2=4*10-7 cm/s
Let the thickness of each layer be z,
Therefore the total thickness is 2z.
For flow parallel to the bedding plane,
\(K_x=\frac{k_1 z_1+k_2 z_2+⋯.+k_n z_n}{z} \)
\(K_x=\frac{z*9*10^{-7}+ z*4*10^{-7}}{2z} \)
∴ Kx=6.5*10-7 cm/s.
2. The coefficient of permeability of the two soil layers 1 and 2 in soil deposit is 9*10-7 cm/s and 4*10-7 cm/s respectively. The thickness of the layers is equal. The value of average permeability perpendicular to bedding planes is ________
a) 4.5*10-7 cm/s
b) 5.5*10-7 cm/s
c) 6.5*10-7 cm/s
d) 7.5*10-7 cm/s
Explanation: Given,
K1=9*10-7 cm/s
K2=4*10-7 cm/s
Let the thickness of each layer be z,
Therefore the total thickness is 2z.
For flow perpendicular to the bedding plane,
\(K_z = \frac{z}{\frac{z_1}{k_1} +\frac{z_2}{k_2} +⋯+\frac{z_n}{k_n}}\)
\(K_z = \frac{2z}{\frac{z}{9*10^{-7}}+\frac{z}{4*10^{-7}}}\)
∴ Kz = 5.5*10-7 cm/s.
3. Which of the following test is commonly adopted for determining soil permeability of soil formations?
a) Pumping-in test and Pumping-out test
b) Horizontal capillary test
c) None of the mentioned
d) All of the mentioned
Explanation: Pumping-out test is the frequently used field method, as it involves discharging water from the ground.
4. The value of specific yield SY, of an aquifer depends on ___________
a) Grain size
b) Compaction of stratum
c) Grain shape
d) All of the mentioned
Explanation: Since specific yield is the volume of water drained, the drainage of water depend on grain size, shape and compaction of stratum in the soil.
5. Specific yield of unconfined aquifer indicates __________
a) Water capacity
b) Volume of water
c) Water retained
d) All of the mentioned
Explanation: Specific yield is an indication of the water yielding capacity of an unconfined aquifer.
6. Dupuit’s theory was later modified by _________
a) Thiem
b) Darcy
c) Alam Singh
d) Louden
Explanation: The theory proposed by Dupuit’s on radial flow was modified by Thiem in 1906.
7. The parabolic depression in the aquifer is called as __________?
a) Cone of depression and Drawdown curve
b) Parabolic curve
c) None of the mentioned
d) All of the mentioned
Explanation: The parabolic depression formed when water is pumped from the aquifer through well can be called as cone of depression or the drawdown surface.
8. In most of the confined aquifers,the value of storage coefficient ranges between __________.
a) 0.05 to 0.0005
b) 0.5 to 0.005
c) 0.00005 to 0.005
d) 0 to 5
Explanation: By pumping test method, the value of storage coefficient ranges was found to be in between 0.00005 to 0.005.
9. Which of the following is depicted by Dupuit’s theory?
a) The velocity of flow
b) Co-efficient of transmissibility
c) Radial flow of water
d) Volume of aquifer
Explanation: The analysis of the radial flow of water to a well was originally proposed by Dupuit’s theory.
10. The co-efficient of transmissibility (T) of an aquifer is given by which of the following equation?
a) T=b k
b) T=b/k
c) T=(b k)2
d) T=k/b
Explanation: The coefficient of transmissibility T is equals the field of co-efficient of permeability K multiplied by the aquifer thickness b:
T=b k.