Engineering Questions with Answers - Multiple Choice Questions

Home » MCQs » Engineering MCQs » Well Hydraulics – Interference among Wells

# 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

**
View Answer**

Answer: bExplanation: 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

**
View Answer**

Answer: cExplanation: 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

**
View Answer**

Answer: aExplanation: 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

**
View Answer**

Answer: bExplanation: 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

**
View Answer**

Answer: cExplanation: 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

**
View Answer**

Answer: cExplanation: 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

**
View Answer**

Answer: cExplanation: 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

**
View Answer**

Answer: cExplanation: In an artesian well, when water level falls below the top of confined aquifer, the flow pattern close to the well is similar to that of gravity well. Hence, it is also known as combined artesian gravity well.