Discharge (\( Q \)):

\[ Q = 3.6 \cdot \frac{A \cdot X}{\sqrt{y}} \]

Where:

• \( Q \) is the discharge, in gallons per minute (gpm).
• \( A \) is the cross-sectional area of water at the end of the pipe, in square inches (in²).
• \( X \) is the coordinate of the point on the surface measured parallel to the pipe, in inches (in).
• \( y \) is the vertical coordinate, in inches (in).