## Method For Determining Runoff

** METHOD FOR DETERMINING RUNOFF FOR MINOR HYDRAULIC STRUCTURES**

*The most common means for determining runoff for minor hydraulic structures is the rational formula:*

*Q=CIA*

*where
Q= peak discharge, ft3/s (m3/s)*

*C =runoff coefficient percentage of rain that appears as direct runoff*

*I= rainfall intensity, in/h (mm/h)*

*A= drainage area, acres (m2)*

* *

*COMPUTING RAINFALL INTENSITY. *

*Chow lists 24 rainfall-intensity formulas of the form:*

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