# Engineering Hydrology Questions and Answers – Regional Flood Frequency Analysis

This set of Engineering Hydrology Multiple Choice Questions & Answers (MCQs) focuses on “Regional Flood Frequency Analysis”.

1. Which of the following is not true regarding regional flood frequency analysis of a catchment?
a) Used when available data in the catchment is less
b) Climatologically homogeneous region is considered
c) Data from neighboring catchments are checked for homogeneity
d) Hydrologically similar catchments are identified

Explanation: When the data of a catchment is so less that a frequency analysis cannot be conducted, a regional analysis is adopted instead. Hydrologically homogeneous regions that are neighboring to the catchment is considered and their data is gathered.

2. What is the definition of a region as per regional flood frequency analysis of a catchment?
a) Group of homogeneous neighboring stations
b) All the neighboring catchments
c) Meteorologically similar areas
d) All catchments within 100 km of the catchment

Explanation: After the neighboring stations of a catchment are checked for homogeneity by analyzing their long term flood data, a group of stations with satisfactory results are selected. These stations combined, constitute a region and are studied as a group.

3. A flood with what return period is used as a non-dimensionalizing quantity in regional flood analysis?
a) 1 year
b) 1.33 years
c) 2 years
d) 2.33 years

Explanation: A flood corresponding to a return period of 2.33 years is called the mean annual flood as per Gumbel analysis. This quantity is used as a non-dimensionalizing factor in regional flood analysis by taking its ratio with the flood discharge for any given return period.

4. How many basic plots are required in the regional flood frequency analysis of a catchment?
a) 1
b) 2
c) 3
d) 4

Explanation: The data of all the neighboring homogeneous stations are pooled together and analyzed as a single region to study the frequency characteristics of the catchment. Two basic plots are drawn using the data of mean annual flood, return period and corresponding flood, and drainage area.

5. Which of the following is a basic plot used in the regional flood frequency analysis of a catchment?
a) Mean annual flood vs. drainage area
b) Mean annual flood vs. return period
c) Ratio of flood and mean annual flood vs. drainage area
d) Ratio of mean annual flood and flood vs. return period

Explanation: The mean annual flood is that which corresponds to a return period of 2.33 years. As the drainage area changes, the mean annual flood for that region also varies. This is one basic variation used in the regional analysis of a catchment.

6. The variation of flood to mean annual flood ratio and return period is a basic plot used in regional analysis of a catchment.
a) True
b) False

Explanation: The flood discharge for a given return period is converted into a ratio by dividing it by the mean annual flood for a given area. This ratio is plotted against the return period to provide a basic plot in regional flood analysis.

Sanfoundry Global Education & Learning Series – Engineering Hydrology.

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