Final answer:
Using the Rational Method, the peak flow rate for 400 acres of asphalt with a runoff coefficient of 0.70 and an intensity of 1in/hr is calculated to be 280 cfs, which corresponds to option A.
Step-by-step explanation:
To calculate the peak flow rate for an area of asphalt for a given rainfall intensity, the Rational Method can be used, which is a widely accepted technique in hydrology for estimating peak discharge. The formula for the Rational Method is:
Q = C x I x A
Where:
- Q is the peak discharge (in cubic feet per second, cfs)
- C is the runoff coefficient for the surface
- I is the rainfall intensity (in inches per hour)
- A is the area (in acres)
For 400 acres of asphalt with a runoff coefficient (C) of 0.70 and a rainfall intensity (I) of 1 inch per hour, the calculation would be:
Q = 0.70 x 1 x 400
Q = 280 cfs
Therefore, the peak flow rate for 400 acres of asphalt under these conditions is 280 cubic feet per second (cfs), which corresponds to option A.