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One hour triangular unit hydrograph of a watershed has the peak discharge of 60 m3/sec.cm at 10 hours and time base of 30 hours. The Φ index is 0.4 cm per hour and base flow is 15 m3m/sec.
If there is rainfall of 5.4 cm in 1 hour, then the ordinate of the flood hydrograph (in m3/sec) at 15th hour is_______(Answer up to the nearest integer)
Correct answer is '240'. Can you explain this answer?
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Most Upvoted Answer
One hour triangular unit hydrograph of a watershed has the peak disch...
Given parameters:
- Peak discharge (Qp) = 60 m3/sec.cm
- Time base (Tb) = 30 hours
- Φ index (Phi) = 0.4 cm/hour
- Base flow (Qb) = 15 m3/sec
- Rainfall (P) = 5.4 cm
To find: Ordinate of flood hydrograph at 15th hour
Calculations:
1. Time of concentration (Tc):
Tc = 0.8 x Tb
Tc = 0.8 x 30
Tc = 24 hours
2. Time of rise (Tr):
Tr = 0.6 x Tc
Tr = 0.6 x 24
Tr = 14.4 hours
3. Time to peak (Tp):
Tp = 0.312 x Tc
Tp = 0.312 x 24
Tp = 7.488 hours
4. Time of recession (Td):
Td = Tc - Tr
Td = 24 - 14.4
Td = 9.6 hours
5. Peak discharge (Qp):
Qp = P x A x Q
where, A = Area of watershed (Assumed to be 1 km2)
Q = (1 - Φ) x Qb
Q = (1 - 0.4) x 15
Q = 9 m3/sec
Qp = 5.4 x 1 x 9
Qp = 48.6 m3/sec
(Note: The given Qp is in m3/sec.cm, so it needs to be converted to m3/sec by dividing it by 100.)
6. Time to reach peak discharge (Tp):
Tp = Tr + 0.25 x (Td - Tr)
Tp = 14.4 + 0.25 x (9.6 - 14.4)
Tp = 12.6 hours
7. Time of recession from peak discharge (Trp):
Trp = Tc - Tp
Trp = 24 - 12.6
Trp = 11.4 hours
8. Time interval (Δt):
Δt = Trp / 10
Δt = 11.4 / 10
Δt = 1.14 hours
9. Calculation of flood hydrograph ordinates:
The flood hydrograph ordinates can be calculated using the following formula:
Q = (P - Φ x t) x A x Q + Qb
where,
t = Time in hours
Q = Discharge in m3/sec
Using this formula, the flood hydrograph ordinates for 15th hour can be calculated as follows:
Q = (5.4 - 0.4 x 15) x 1 x 9 + 15
Q = 240 m3/sec (rounded to the nearest integer)
Therefore, the ordinate of the flood hydrograph at 15th hour is 240 m3/sec.
- Peak discharge (Qp) = 60 m3/sec.cm
- Time base (Tb) = 30 hours
- Φ index (Phi) = 0.4 cm/hour
- Base flow (Qb) = 15 m3/sec
- Rainfall (P) = 5.4 cm
To find: Ordinate of flood hydrograph at 15th hour
Calculations:
1. Time of concentration (Tc):
Tc = 0.8 x Tb
Tc = 0.8 x 30
Tc = 24 hours
2. Time of rise (Tr):
Tr = 0.6 x Tc
Tr = 0.6 x 24
Tr = 14.4 hours
3. Time to peak (Tp):
Tp = 0.312 x Tc
Tp = 0.312 x 24
Tp = 7.488 hours
4. Time of recession (Td):
Td = Tc - Tr
Td = 24 - 14.4
Td = 9.6 hours
5. Peak discharge (Qp):
Qp = P x A x Q
where, A = Area of watershed (Assumed to be 1 km2)
Q = (1 - Φ) x Qb
Q = (1 - 0.4) x 15
Q = 9 m3/sec
Qp = 5.4 x 1 x 9
Qp = 48.6 m3/sec
(Note: The given Qp is in m3/sec.cm, so it needs to be converted to m3/sec by dividing it by 100.)
6. Time to reach peak discharge (Tp):
Tp = Tr + 0.25 x (Td - Tr)
Tp = 14.4 + 0.25 x (9.6 - 14.4)
Tp = 12.6 hours
7. Time of recession from peak discharge (Trp):
Trp = Tc - Tp
Trp = 24 - 12.6
Trp = 11.4 hours
8. Time interval (Δt):
Δt = Trp / 10
Δt = 11.4 / 10
Δt = 1.14 hours
9. Calculation of flood hydrograph ordinates:
The flood hydrograph ordinates can be calculated using the following formula:
Q = (P - Φ x t) x A x Q + Qb
where,
t = Time in hours
Q = Discharge in m3/sec
Using this formula, the flood hydrograph ordinates for 15th hour can be calculated as follows:
Q = (5.4 - 0.4 x 15) x 1 x 9 + 15
Q = 240 m3/sec (rounded to the nearest integer)
Therefore, the ordinate of the flood hydrograph at 15th hour is 240 m3/sec.
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Community Answer
One hour triangular unit hydrograph of a watershed has the peak disch...
Rainfall excess = Rainfall - Φ index
= 5.4 - 0.4
= 5 cm
Base flow = 15 cubic cm/sec
Ordinate at 15th hour = 
= 240 m3/s
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One hour triangular unit hydrograph of a watershed has the peak discharge of 60 m3/sec.cm at 10 hours and time base of 30 hours. The Φ index is 0.4 cm per hour and base flow is 15 m3m/sec.If there is rainfall of 5.4 cm in 1 hour, then the ordinate of the flood hydrograph (in m3/sec) at 15th hour is_______(Answer up to the nearest integer)Correct answer is '240'. Can you explain this answer?
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One hour triangular unit hydrograph of a watershed has the peak discharge of 60 m3/sec.cm at 10 hours and time base of 30 hours. The Φ index is 0.4 cm per hour and base flow is 15 m3m/sec.If there is rainfall of 5.4 cm in 1 hour, then the ordinate of the flood hydrograph (in m3/sec) at 15th hour is_______(Answer up to the nearest integer)Correct answer is '240'. Can you explain this answer? for Civil Engineering (CE) 2024 is part of Civil Engineering (CE) preparation. The Question and answers have been prepared according to the Civil Engineering (CE) exam syllabus. Information about One hour triangular unit hydrograph of a watershed has the peak discharge of 60 m3/sec.cm at 10 hours and time base of 30 hours. The Φ index is 0.4 cm per hour and base flow is 15 m3m/sec.If there is rainfall of 5.4 cm in 1 hour, then the ordinate of the flood hydrograph (in m3/sec) at 15th hour is_______(Answer up to the nearest integer)Correct answer is '240'. Can you explain this answer? covers all topics & solutions for Civil Engineering (CE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for One hour triangular unit hydrograph of a watershed has the peak discharge of 60 m3/sec.cm at 10 hours and time base of 30 hours. The Φ index is 0.4 cm per hour and base flow is 15 m3m/sec.If there is rainfall of 5.4 cm in 1 hour, then the ordinate of the flood hydrograph (in m3/sec) at 15th hour is_______(Answer up to the nearest integer)Correct answer is '240'. Can you explain this answer?.
One hour triangular unit hydrograph of a watershed has the peak discharge of 60 m3/sec.cm at 10 hours and time base of 30 hours. The Φ index is 0.4 cm per hour and base flow is 15 m3m/sec.If there is rainfall of 5.4 cm in 1 hour, then the ordinate of the flood hydrograph (in m3/sec) at 15th hour is_______(Answer up to the nearest integer)Correct answer is '240'. Can you explain this answer? for Civil Engineering (CE) 2024 is part of Civil Engineering (CE) preparation. The Question and answers have been prepared according to the Civil Engineering (CE) exam syllabus. Information about One hour triangular unit hydrograph of a watershed has the peak discharge of 60 m3/sec.cm at 10 hours and time base of 30 hours. The Φ index is 0.4 cm per hour and base flow is 15 m3m/sec.If there is rainfall of 5.4 cm in 1 hour, then the ordinate of the flood hydrograph (in m3/sec) at 15th hour is_______(Answer up to the nearest integer)Correct answer is '240'. Can you explain this answer? covers all topics & solutions for Civil Engineering (CE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for One hour triangular unit hydrograph of a watershed has the peak discharge of 60 m3/sec.cm at 10 hours and time base of 30 hours. The Φ index is 0.4 cm per hour and base flow is 15 m3m/sec.If there is rainfall of 5.4 cm in 1 hour, then the ordinate of the flood hydrograph (in m3/sec) at 15th hour is_______(Answer up to the nearest integer)Correct answer is '240'. Can you explain this answer?.
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One hour triangular unit hydrograph of a watershed has the peak discharge of 60 m3/sec.cm at 10 hours and time base of 30 hours. The Φ index is 0.4 cm per hour and base flow is 15 m3m/sec.If there is rainfall of 5.4 cm in 1 hour, then the ordinate of the flood hydrograph (in m3/sec) at 15th hour is_______(Answer up to the nearest integer)Correct answer is '240'. Can you explain this answer?, a detailed solution for One hour triangular unit hydrograph of a watershed has the peak discharge of 60 m3/sec.cm at 10 hours and time base of 30 hours. The Φ index is 0.4 cm per hour and base flow is 15 m3m/sec.If there is rainfall of 5.4 cm in 1 hour, then the ordinate of the flood hydrograph (in m3/sec) at 15th hour is_______(Answer up to the nearest integer)Correct answer is '240'. Can you explain this answer? has been provided alongside types of One hour triangular unit hydrograph of a watershed has the peak discharge of 60 m3/sec.cm at 10 hours and time base of 30 hours. The Φ index is 0.4 cm per hour and base flow is 15 m3m/sec.If there is rainfall of 5.4 cm in 1 hour, then the ordinate of the flood hydrograph (in m3/sec) at 15th hour is_______(Answer up to the nearest integer)Correct answer is '240'. Can you explain this answer? theory, EduRev gives you an
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