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Stormwater runoff volume is calculated using rainfall and surface area characteristics. It's essential for drainage system design.

Formula

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

Guida passo passo

  1. 1Use rational method: Q = C×I×A where C is runoff coefficient, I is rainfall intensity, A is area
  2. 2C varies by surface: impervious (0.8-0.95), pervious (0.1-0.3)
  3. 3Results show peak flow for design storm

Esempi risolti

Ingresso
Area 10 ha, 60% impervious, rainfall 100 mm/hr
Risultato
Q ≈ 1.8 m³/s peak flow
For drainage system sizing

Errori comuni da evitare

  • Using wrong rainfall intensity for design frequency
  • Neglecting impervious surface increases from development

Domande frequenti

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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