How do you determine hydraulic capacity of a storm water drainage pipe?

The hydraulic capacity of a stormwater drainage pipe is determined using the Manning's equation, which calculates flow based on the pipe's diameter, slope, and roughness coefficient. The equation considers the cross-sectional area of flow and the hydraulic radius to assess how much water the pipe can transport. Additionally, factors such as inlet conditions, pipe material, and any potential obstructions should be evaluated to ensure accurate capacity estimation. Flow rate measurements can also be conducted to validate theoretical calculations.