Driveway Runoff Calculator — Calculate Surface Water Runoff from Your Driveway

Driveway Runoff Calculator

Calculate rainwater runoff volume from your driveway or paved surface. Estimate drainage requirements and environmental impact for proper water management.

Step 1: Surface Details

Understanding Runoff Coefficients

Runoff coefficient (C) represents the fraction of rainfall that becomes surface runoff. Impervious surfaces like asphalt have higher coefficients (0.8-0.95) while permeable surfaces have lower values (0.05-0.35).

Step 2: Rainfall Details

Runoff Calculation Formula

Runoff Volume = Area × Rainfall Depth × Runoff Coefficient. This simplified Rational Method helps estimate peak runoff rates for small drainage areas. Actual runoff may vary based on slope, soil type, and antecedent moisture.

Driveway Runoff Calculation Results

Summary
Surface Comparison
Runoff Analysis

Estimated Runoff Volume from Your Driveway

832.5 gallons
Peak Flow Rate: 13.88 gal/min
Driveway Area
1,000 sq ft
Runoff Coefficient
0.95
Runoff Depth
0.95 inches
Environmental Impact
High

Surface Type Runoff Comparison

Surface Type Runoff Coefficient Runoff Volume Infiltration Rate Environmental Impact

Rainfall-Runoff Analysis

Runoff Calculation Formula

Q = C × I × A

Where: Q = Runoff volume, C = Runoff coefficient, I = Rainfall intensity, A = Area. The Rational Method is commonly used for small drainage areas to estimate peak runoff rates for stormwater management design.

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