Drain Flow Rate Calculator

Formula

To calculate the drain flow rate:

DFR = (C × R × A) / 96.23

Where:

DFR is the Drain Flow Rate (GPM)
C is the coefficient of runoff
R is the rainfall intensity (in/hr)
A is the area of drainage zone (acres)

What is Drain Flow Rate?

Drain flow rate refers to the volume of water that flows through a drainage system over a given period, typically measured in gallons per minute (GPM). It is calculated based on the coefficient of runoff, rainfall intensity, and the area of the drainage zone. This calculation is essential in designing effective drainage systems to prevent flooding and manage water flow.

Example Calculation 1

Let's assume the following values:

Coefficient of Runoff (C): 0.5
Rainfall Intensity (R): 2 in/hr
Area of Drainage Zone (A): 1 acre

Using the formula:

DFR = (C × R × A) / 96.23 = (0.5 × 2 × 1) / 96.23 ≈ 0.0104 GPM

Example Calculation 2

Let's assume the following values:

Coefficient of Runoff (C): 0.7
Rainfall Intensity (R): 1.5 in/hr
Area of Drainage Zone (A): 2 acres

Using the formula:

DFR = (C × R × A) / 96.23 = (0.7 × 1.5 × 2) / 96.23 ≈ 0.0218 GPM