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If the base period of a 6 hr unit hydrograph (UH) of a basin is 84 hours, then a 12 hr unit hydrograph derived from this 6 hr unit hydrograph will have a base period of :
- a)72 h
- b)78 h
- c)84 h
- d)90 h
Correct answer is option 'D'. Can you explain this answer?
Verified Answer
If the base period of a 6 hr unithydrograph (UH) of a basin is 84hours...
To obtain 12 hr UH, we lag 6hr UH by another 6 hours hence, base period of 12 hr UH is 84 + 6 = 90 hr.
Most Upvoted Answer
If the base period of a 6 hr unithydrograph (UH) of a basin is 84hours...
Explanation:
A unit hydrograph (UH) is defined as the hydrograph resulting from a unit depth of excess rainfall occurring uniformly over the basin and uniformly distributed over the duration of the excess rainfall. It represents the direct runoff from a basin due to a unit depth of rainfall.
The base period of a unit hydrograph is the time interval between the centroid of the excess rainfall and the peak of the resulting unit hydrograph. It represents the time taken for the direct runoff to reach its peak value.
Given:
Base period of a 6 hr unit hydrograph = 84 hours.
To find:
Base period of a 12 hr unit hydrograph derived from this 6 hr unit hydrograph.
Solution:
When a 12 hr unit hydrograph is derived from a 6 hr unit hydrograph, the area under the 12 hr unit hydrograph is twice the area under the 6 hr unit hydrograph. Therefore, the time base of the 12 hr unit hydrograph will be twice the time base of the 6 hr unit hydrograph.
Time base of a 6 hr unit hydrograph = 84 hours.
Time base of a 12 hr unit hydrograph = 2 x 84 = 168 hours.
But the base period of a unit hydrograph is the time interval between the centroid of the excess rainfall and the peak of the resulting unit hydrograph. The centroid time of the excess rainfall remains the same for both the 6 hr and 12 hr unit hydrographs because the rainfall depth and duration are the same. Therefore, the base period of the 12 hr unit hydrograph will also be the same as the base period of the 6 hr unit hydrograph.
Thus, the base period of the 12 hr unit hydrograph derived from a 6 hr unit hydrograph with a base period of 84 hours is 84 hours, which is option D.
A unit hydrograph (UH) is defined as the hydrograph resulting from a unit depth of excess rainfall occurring uniformly over the basin and uniformly distributed over the duration of the excess rainfall. It represents the direct runoff from a basin due to a unit depth of rainfall.
The base period of a unit hydrograph is the time interval between the centroid of the excess rainfall and the peak of the resulting unit hydrograph. It represents the time taken for the direct runoff to reach its peak value.
Given:
Base period of a 6 hr unit hydrograph = 84 hours.
To find:
Base period of a 12 hr unit hydrograph derived from this 6 hr unit hydrograph.
Solution:
When a 12 hr unit hydrograph is derived from a 6 hr unit hydrograph, the area under the 12 hr unit hydrograph is twice the area under the 6 hr unit hydrograph. Therefore, the time base of the 12 hr unit hydrograph will be twice the time base of the 6 hr unit hydrograph.
Time base of a 6 hr unit hydrograph = 84 hours.
Time base of a 12 hr unit hydrograph = 2 x 84 = 168 hours.
But the base period of a unit hydrograph is the time interval between the centroid of the excess rainfall and the peak of the resulting unit hydrograph. The centroid time of the excess rainfall remains the same for both the 6 hr and 12 hr unit hydrographs because the rainfall depth and duration are the same. Therefore, the base period of the 12 hr unit hydrograph will also be the same as the base period of the 6 hr unit hydrograph.
Thus, the base period of the 12 hr unit hydrograph derived from a 6 hr unit hydrograph with a base period of 84 hours is 84 hours, which is option D.
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If the base period of a 6 hr unithydrograph (UH) of a basin is 84hours, then a 12 hr unit hydrograph derived from this 6 hr unithydrograph will have a base periodof :a)72 hb)78 hc)84 hd)90 hCorrect answer is option 'D'. Can you explain this answer? for Civil Engineering (CE) 2025 is part of Civil Engineering (CE) preparation. The Question and answers have been prepared according to the Civil Engineering (CE) exam syllabus. Information about If the base period of a 6 hr unithydrograph (UH) of a basin is 84hours, then a 12 hr unit hydrograph derived from this 6 hr unithydrograph will have a base periodof :a)72 hb)78 hc)84 hd)90 hCorrect answer is option 'D'. Can you explain this answer? covers all topics & solutions for Civil Engineering (CE) 2025 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for If the base period of a 6 hr unithydrograph (UH) of a basin is 84hours, then a 12 hr unit hydrograph derived from this 6 hr unithydrograph will have a base periodof :a)72 hb)78 hc)84 hd)90 hCorrect answer is option 'D'. Can you explain this answer?.
If the base period of a 6 hr unithydrograph (UH) of a basin is 84hours, then a 12 hr unit hydrograph derived from this 6 hr unithydrograph will have a base periodof :a)72 hb)78 hc)84 hd)90 hCorrect answer is option 'D'. Can you explain this answer? for Civil Engineering (CE) 2025 is part of Civil Engineering (CE) preparation. The Question and answers have been prepared according to the Civil Engineering (CE) exam syllabus. Information about If the base period of a 6 hr unithydrograph (UH) of a basin is 84hours, then a 12 hr unit hydrograph derived from this 6 hr unithydrograph will have a base periodof :a)72 hb)78 hc)84 hd)90 hCorrect answer is option 'D'. Can you explain this answer? covers all topics & solutions for Civil Engineering (CE) 2025 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for If the base period of a 6 hr unithydrograph (UH) of a basin is 84hours, then a 12 hr unit hydrograph derived from this 6 hr unithydrograph will have a base periodof :a)72 hb)78 hc)84 hd)90 hCorrect answer is option 'D'. Can you explain this answer?.
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If the base period of a 6 hr unithydrograph (UH) of a basin is 84hours, then a 12 hr unit hydrograph derived from this 6 hr unithydrograph will have a base periodof :a)72 hb)78 hc)84 hd)90 hCorrect answer is option 'D'. Can you explain this answer?, a detailed solution for If the base period of a 6 hr unithydrograph (UH) of a basin is 84hours, then a 12 hr unit hydrograph derived from this 6 hr unithydrograph will have a base periodof :a)72 hb)78 hc)84 hd)90 hCorrect answer is option 'D'. Can you explain this answer? has been provided alongside types of If the base period of a 6 hr unithydrograph (UH) of a basin is 84hours, then a 12 hr unit hydrograph derived from this 6 hr unithydrograph will have a base periodof :a)72 hb)78 hc)84 hd)90 hCorrect answer is option 'D'. Can you explain this answer? theory, EduRev gives you an
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