This set of Engineering Hydrology Multiple Choice Questions & Answers (MCQs) focuses on “Groundwater – Well Loss”.
1. The total drawdown in an artesian pumping well generally consists of how many parts?
a) 1
b) 2
c) 3
d) 4
View Answer
Explanation: The drawdown inside a pumping well present in a confined aquifer is generally considered to be made of two parts – formation loss and well loss. This is because of the different relation of parts of drawdown to the discharge out of the well.
2. Which of the following is called formation loss of a pumping well?
a) Head loss required to cause laminar flow in a confined aquifer
b) Head loss required to cause turbulent flow in a confined aquifer
c) Head loss required to cause laminar flow in an unconfined aquifer
d) Head loss required to cause turbulent flow in an unconfined aquifer
View Answer
Explanation: The formation loss in pumping wells in confined aquifer is the major contributor to drawdown in the well. It is defined as the head drop required to cause laminar flow in the aquifer medium.
3. Which of the following is a type of loss, which is not a formation loss, in a pumping well in an artesian aquifer?
a) Head loss to maintain laminar flow far from the well
b) Head loss to maintain laminar flow near to the well
c) Head loss to maintain turbulent flow far from the well
d) Head loss to maintain turbulent flow near to the well
View Answer
Explanation: Other than the formation loss, another contributor to the well drawdown is the drop in piezometric head so as to sustain the turbulent flow in regions near to the well, where the Reynold’s number is greater than 1.
4. Which of the following is a minor loss in artesian pumping wells that contributes to the overall drawdown?
a) Formation loss
b) Loss through well casing
c) Loss to cause laminar flow
d) Loss to sustain laminar flow
View Answer
Explanation: Other than the head losses required to cause laminar flow in the aquifer and sustain turbulent flow near the well, there is another minor loss that contributes to the drawdown in the well. This is the head lost through the well screen and well casing.
5. If A and B represent the formation loss and well loss, respectively for an artesian well pumping a discharge at rate Q, which of the following is true?
a) A∝Q;B∝Q
b) A∝Q2;B∝Q
c) A∝Q;B∝Q2
d) A∝Q2;B∝Q2
View Answer
Explanation: The main difference between the formation loss and well loss in an artesian pumping aquifer is their relationship with the discharge rate. The formation loss is directly proportional to Q, whereas the well loss is directly proportional to Q2.
6. The total drawdown (S) in a well in a confined aquifer is represented by which of the following? Let Q be the pumping rate and a, b, c be the well constants.
a) S=aQ
b) S=a+bQ
c) S=aQ+bQ2
d) S=a+bQ+cQ2
View Answer
Explanation: The drawdown in the well can be attributed to two terms, that is the formation loss and well loss. In S=aQ+bQ2, aQ represents the formation loss term and bQ represents the well loss term.
7. High well loss indicates clogging of well screens.
a) True
b) False
View Answer
Explanation: The amount of well loss affects the pump efficiency of the well. Very high values of well loss signals clogging of screens and other issues, that need immediate remedial measures.
Sanfoundry Global Education & Learning Series – Engineering Hydrology.
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