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For a 109 ha watershed with a time of concentration of 120 minutes and an excess rain of 31 mm, calculate the peak discharge using a typical SCS synthetic hydrograph. Choose the correct answer:

A. Qp = 3.52 m³/s
B. Qp = 7.00 m³/s
C. Qp = 5.25 m³/s
D. Qp = 52.53 m³/s
E. Qp = 0.53 m³/s

Answer :

Assuming a runoff coefficient of 0.6, the calculated peak discharge is around 0.52 cubic meters/second, closest to option e. Qp = 0.53 [tex]m^3/s[/tex]/.

Area (A) = 109 hectares = 109 × [tex]10^{4[/tex] square meters

Time of concentration = 120 minutes = 2 hours

Excess rain (E) = 31 mm

Assuming Runoff coefficient (C) = 0.6 (for demonstration)

1. Calculate Rainfall Intensity (i):

Rainfall intensity is calculated by dividing the excess rain by the time of concentration:

i = E / Time of concentration = 31 mm / 2 hours

Converting hours to seconds:

i = 31 mm / (2 hours × 3600 seconds/hour) = 2.72 × [tex]10^{-6[/tex] meters/second

2. Calculate Peak Discharge (Qp):

The peak discharge is calculated using the Rational Method formula:

Qp = (C × i × A) / 3600

Substitute the values:

Qp = (0.6 × 2.72 × [tex]10^{-6[/tex] × 109 × [tex]10{^4[/tex]) / 3600 = 0.52 cubic meters/second

Among the provided options, the closest value to the calculated peak discharge is:

Qp = 0.53 cubic meters/second

To learn more questions about runoff coefficient,

https://brainly.com/question/34801767

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