# Rainwater Runoff (or) Storm Water Runoff Calculator Using Rational Method

# Rainwater Runoff Calculator

This is to calculate and store your property rainwater runoff.

in

sq.ft

# Rainwater Runoff Formulas

Q = (C x I x A )/96.23

Where,

Q is the storm-water Run-off in Gallons Per Minute (GPM)

C is the Run-off coefficient

I is the Rainfall intensity in inches per hour

A is the Drainage Area in square feet

96.23 is a conversion factor when you want the flow rate in GPM and your driange area in square feet

#### Hundred Year Rainfall Map

The above maps shows the rainfall in inches