Engineering Questions with Answers - Multiple Choice Questions

# Well Hydraulics – Interference among Wells

1 - Question

When two wells are situated near each other, the discharge in individual well is ________
a) increased
b) decreased
c) not effected
d) remains same with respect to each other
Explanation: When two wells are situated near each other, their drawdown curves intersect within their radii of zero drawdown. Thus, the discharge in individual well is decreased.

2 - Question

The discharge for drawdown of well is given by _______
a) q=2πkb(H−h)log10Rr
b) q=2πkb(H−h)logerR
c) q=2πkb(H−h)logeRr
d) q=kb(H−h)logeRr
Explanation: The formula for discharge for drawdown of well is given by, q=2πkb(H−h)logeRr where, q=discharge k=coefficient of permeability b=aquifer thickness R=radius of influence r=radius of tube well (H-h)=drawdown.

3 - Question

The formula for discharge for two wells at distance B is given by ____________
a) q1=q2=2πkb(H−h)logeR2rB
b) q1=q2=2πkb(H−h)BlogerR
c) q1=q2=2πkb(H−h)logeRBr
d) q1=q2=kb(H−h)logeRrB
Explanation: The formula for discharge for two wells at distance B is given by, q1=q2=2πkb(H−h)logeR2rB where, q1=q2=discharge in wells 1 and 2 respectively k=coefficient of permeability b=aquifer thickness R=radius of influence r=radius of tube well (H-h)=drawdown.

4 - Question

The formula for discharge for three wells forming an equilateral triangle at distance B on side is given by ____________
a) q1=q2=q3=2πkb(H−h)logeR2rB
b) q1=q2=q3=2πkb(H−h)logeR3rB2
c) q1=q2=q3=2πkb(H−h)logeRBr
d) q1=q2=q3=kb(H−h)logeRrB
Explanation: The formula for discharge for three wells forming an equilateral triangle at distance B on side is given by, q1=q2=q3=2πkb(H−h)logeR3rB2, where, q1=q2=q3=discharge in wells 1 and 2 respectively k=coefficient of permeability b=aquifer thickness R=radius of influence r=radius of tube well (H-h)=drawdown.

5 - Question

Two tube wells of 20cm diameter each are 100m apart. The coefficient of permeability is 4.15 * 10-4 m/s, drawdown is 4m and aquifer is 30m thick. If radius of influence is 245m, what is the discharge in each well?
a) 0.033 m3/s
b) 0.040 m3/s
c) 0.036 m3/s
d) 0.042 m3/s
Explanation: Given, Interface among two wells, B=100m Radius of tube well=10cm=0.1m coefficient of permeability is 4.15 * 10-4 m/s drawdown (H-h)=4m aquifer=30m radius of influence=245m the discharge is given by, q1=q2=2πkb(H−h)logeR2rB q1=q2=2π∗4.15∗10(−4)∗30∗4loge24520.1∗100 ∴ q1=q2=0.036 m3/s.

6 - Question

In a tube well of 20cm diameter in a soil with coefficient of permeability of 4.15 * 10-4m/s, drawdown is 4m and aquifer is 30m thick. If radius of influence is 245m, what is the discharge in each well?
a) 0.033 m3/s
b) 0.040 m3/s
c) 0.036 m3/s
d) 0.042 m3/s
Explanation: Given, Radius of tube well=10cm=0.1m coefficient of permeability is 4.15 * 10-4 m/s drawdown (H-h)=4m aquifer=30m radius of influence=245m the discharge is given by, q=2πkb(H−h)logeRr q=2π∗4.15∗10−4∗30∗4loge2450.1 ∴ q=0.040 m3/s.

7 - Question

Three tube wells of 20cm diameter each forming an equilateral triangle at distance 100m on side. The coefficient of permeability is 4.15 * 10-4 m/s, drawdown is 4m and aquifer is 30m thick. If radius of influence is 245m, what is the discharge in each well?
a) 0.033 m3/s
b) 0.040 m3/s
c) 0.036 m3/s
d) 0.042 m3/s
Explanation: Given, Interface among three wells, B=100m Radius of tube well=10cm=0.1m coefficient of permeability is 4.15 * 10-4 m/s drawdown (H-h)=4m aquifer=30m radius of influence=245m the discharge is given by, q1=q2=q3=2πkb(H−h)logeR3rB2 q1=q2=q3=2π∗4.15∗10−4∗30∗4loge24530.1∗1002 ∴ q1=q2=q3=0.033 m3/s.

8 - Question

In a artesian well, when water level falls below the top of confined aquifer, then this type of well is known as ______
a) well in unconfined aquifer
b) gravity well
c) combined artesian gravity well
d) artesian well