# Engineering Hydrology Questions and Answers – Factors Affecting Flood Hydrograph – Set 2

This set of Engineering Hydrology Multiple Choice Questions & Answers (MCQs) focuses on “Factors Affecting Flood Hydrograph – Set 2”.

1. In smaller catchments, the overland phase is more predominant over channel flow phase.
a) True
b) False

Explanation: The size of the basin is highly important as it decides the reason behind the occurrence of the peak of the hydrograph. Small basins behave differently from larger basins. In case of smaller basins, the overland phase is predominant over the channel flow phase. Therefore, the rainfall intensity and the land use have important role in determining the peak flood.

2. Which phase is predominant in the case of larger basins?
a) Overland phase
b) Peak phase
c) Discharge phase
d) Channel flow phase

Explanation: In the case of larger basins, the channel flow phase is predominant over overland phase. The peak discharge depends on the channel flow phase mostly. In larger basins the time base of hydrographs is larger than the time base of hydrographs from smaller basins.

3. In case of large catchments, the peak discharge occurs ____________
a) Arithmetically
b) Geometrically
c) Exponentially
d) Parabolically

Explanation: In the case of larger catchments, the peak discharge occurs exponentially. If “A” is the area of catchment and “n” is a number less than unity then the peak discharge occurs as An.

4. The slope of the main stream influences which characteristic of the channel?
a) Discharge of the channel
b) Velocity of flow
c) Pressure of flow
d) Viscosity of fluid

Explanation: The slope of the main stream determines the velocity of flow in the channel. Main streams with larger slopes have more velocity of flow. This velocity of flow effects the shape of the hydrograph.

5. The slope of the main stream will have pronounced effect on the recession limb of the hydrograph.
a) True
b) False

Explanation: The recession limb of the hydrograph depicts the depletion of storage. So, in case of larger slopes, the depletion of storage will take place at a faster rate. So, for larger slopes, the recession limb of the hydrograph will be steeper.

6. In small catchments, sloped basins give high __________
a) Peak discharge
b) Storage
c) Base flow
d) Surface runoff

Explanation: In small catchments, sloped basins are highly important. Overland phase is predominant in small catchment so larger slopes of the basins will give high peak discharge. In case of larger slopes, the time base of the hydrograph is small.

7. What is drainage density?
a) Total channel width / Total drainage area
b) Total channel length / Total drainage area
c) Drainage area / Total channel length
d) Drainage area / Total channel width

Explanation: Drainage density is defined as the ratio of total channel length to drainage area. Drainage density determines the disposal of runoff down the channels.

8. A large drainage density creates a situation of slow disposal of runoff down the channels.
a) True
b) False

Explanation: When the drainage density is more, it is suitable for quick disposal of runoff down the channels. This quick response gives higher peak discharge.

9. The hydrograph is squat in case of _____________
a) High drainage density
b) Smaller drainage density
c) High baseflow
d) Smaller baseflow

Explanation: In areas having smaller drainage density, the overland phase is predominant. The hydrograph obtained in such areas is squat and has slowly rising limb.

10. Vegetation cover increases peak discharge.
a) True
b) False

Explanation: Vegetation and forest increases infiltration and retards overland flow. Therefore, vegetation reduces peak flow or peak discharge.

Sanfoundry Global Education & Learning Series – Engineering Hydrology.

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