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Stormwater runoff volume is calculated using rainfall and surface area characteristics. It's essential for drainage system design.
Formule
Use rational method: Q = C×I×A where C is runoff coefficient, I is rainfall intensity, A is area
- Q
- C×I×A where C is runoff coefficient — C×I×A where C is runoff coefficient
- C
- C value — Variable used in the calculation
- I
- I value — Variable used in the calculation
- A
- A value — Variable used in the calculation
Guide étape par étape
- 1Use rational method: Q = C×I×A where C is runoff coefficient, I is rainfall intensity, A is area
- 2C varies by surface: impervious (0.8-0.95), pervious (0.1-0.3)
- 3Results show peak flow for design storm
Exemples résolus
Entrée
Area 10 ha, 60% impervious, rainfall 100 mm/hr
Résultat
Q ≈ 1.8 m³/s peak flow
For drainage system sizing
Erreurs courantes à éviter
- ✕Using wrong rainfall intensity for design frequency
- ✕Neglecting impervious surface increases from development
Questions fréquentes
Why use runoff coefficient?
Not all rain becomes runoff; some infiltrates soil. Coefficient captures this fraction.
What storm frequency should be designed for?
Typically 10-year storm for urban areas, 100-year for critical facilities, varies by code.
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