Engineering Hydrology Questions and Answers – Hydrograph Components

This set of Engineering Hydrology Multiple Choice Questions & Answers (MCQs) focuses on “Hydrograph Components”.

1. Which one of the following is not a component of hydrograph?
a) Recession limb
b) Rising arm
c) Crest
d) Rising limb

Explanation: The components of hydrograph include the following:
i) Rising limb
ii) Crest
iii) Recession limb

2. Which part of the hydrograph is known as concentration curve?
a) Rising limb
b) Crest
c) Recession limb
d) Depletion curve

Explanation: Rising limb of hydrograph is known as concentration curve. It represents the increase in discharge due to storage in channels and catchment area.

3. In case of uniform storm, the runoff increases slowly a catchment area.
a) True
b) False

Explanation: When the storm begins, the initial losses and the infiltration losses are high. After sometime as the storm continues, the infiltration loss decreases and the surface runoff increases. So, for uniform storm, the runoff increases rapidly throughout the storm.

4. What does the crest segment represent?
a) Discharge
b) Baseflow
c) Peak flow
d) Depletion curve

Explanation: The crest part of the hydrograph represents the peak flow. The total amount of discharge is collected from different parts of the catchment and accumulated at the basin outlet. This accumulated water helps to give the peak flow.

5. In large catchments, the peak flow is generally obtained after cessation of rainfall.
a) True
b) False

Explanation: In large catchments, the maximum flow at the basin outlet is obtained after the cessation of rainfall. The time interval from the centre of mass of rainfall to the peak flow is controlled by basin and storm characteristics.

6. When two or more storms occur in succession then which of the following hydrograph is obtained?
a) Single-peaked hydrograph
b) Single limb hydrograph
c) Double-peaked hydrograph
d) Multiple-peaked hydrograph

Explanation: When two or more storms occur in succession in a catchment area then multi-peaked hydrograph is obtained. In this case, the hydrograph will have two or more crest portions.

7. The portion of the hydrograph starting from the end of crest portion and extending upto the commencement of groundwater flow is known as ___________
a) Rising limb
b) End limb
c) Rising arm
d) Recession limb

Explanation: The portion of the hydrograph starting from the end of crest that is point of inflection up to the commencement of ground water flow is called the recession limb. It represents the depletion of the built-up storage.

8. The characteristics of recession limb depends entirely on basin characteristics and not on storm characteristics.
a) True
b) False

Explanation: The recession limb represents the portion of the hydrograph starting from point of inflection to the start of base flow. It actually depicts the clearing up of built-up storage. This phase generally takes place after the cessation of rainfall. So, the characteristics or features of recession limb depends entirely on basin characteristics and not on storm characteristics.

9. The surface storage includes which of the following?
a) Baseflow
b) Channel storage and surface detention
c) Channel storage
d) Surface detention

Explanation: The storage in the basin is accumulated by different sources. Surface storage includes surface detention and channel storage. The maximum storage in the basin gives the peak flow.

10. Which of the following is not a form of storage of basin?
a) Underflow storage
b) Interflow storage
c) Surface storage
d) Groundwater storage

Explanation: The basin storage exists in the following forms:
i) Surface storage – Surface storage consists of surface detention and channel storage
ii) Interflow storage
iii) Groundwater storage

11. Which one of the following gives the Barne’s equation for recession of storage?
(Symbols have their usual meanings)
a) Qt = Q0Krt
b) Qt = Q0Kr
c) Qt = Krt
d) Qt = Q0Krt*2

Explanation: In 1940, Barne has given an equation for the recession of storage. It is as follows:
Qt = Q0Krt
Where,
Qt = discharge at time t
Q0 = discharge at time t = 0
Kr = Recession constant having value less than unity

12. The recession constant Kr is made up of three constants Krs, Kri & Krb. State the formula
a) Kr = Krs + Kri + Krb
b) Kr = Krs / Kri * Krb
c) Kr = (Krs + Kri) * Krb
d) Kr = Krs * Kri * Krb

Explanation: The recession constant Kr is estimated by considering three constants. The formula is as follows:
Kr = Krs * Kri * Krb
Krs = Constant due to surface storage
Kri = Constant due to interflow storage
Krb = Constant due to groundwater storage

13. What is the range of value for recession constant for surface storage?
a) 0.5 to 1
b) 0.05 to 0.2
c) 0.6 to 2
d) 0.3 to 1.5

Explanation: The recession storage constant is of three forms. Recession storage constant for surface storage (Krs) has the value in the range of 0.05 to 0.2.

14. What is the range of value of recession constant due to interflow storage?
a) 0.05 to 0.6
b) 0.3 to 0.5
c) 0.1 to 0.3
d) 0.5 to 0.85

Explanation: The recession constant for interflow storage (Kri) has a value ranging from 0.5 to 0.85. If the interflow is not significant then the recession constant due to interflow storage is considered to be unity.

Sanfoundry Global Education & Learning Series – Engineering Hydrology.

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