SCS Curve Number
Calculate runoff depth using the USDA SCS (NRCS) Curve Number method. Determine runoff, infiltration, and initial abstraction from precipitation and curve number.
Inputs
Results
Runoff Depth
41.14 mm
Potential Max Retention (S)
84.67 mm
How to Use This Calculator
- Enter Precipitation and Curve Number (CN).
- Review Runoff Depth (mm) and Potential Max Retention (S) (mm).
- Use Initial Abstraction (Ia) (mm) and Infiltration (mm) to inform your decision.
- Use the chart to visualize the results and explore different scenarios by adjusting inputs.
Formula
S = 25400/CN - 254; Q = (P - 0.2S)² / (P + 0.8S)Related Calculators
Rational Method Runoff
Calculate peak stormwater discharge using the Rational Method (Q = CIA/360). Estimate runoff from rainfall intensity, runoff coefficient, and catchment area.
Watershed Area Calculator
Calculate drainage area and morphometric parameters of a watershed from perimeter, shape factor, and longest flow path.
Unit Hydrograph Calculator
Calculate the SCS triangular unit hydrograph peak flow, time to peak, and time base from drainage area, lag time, and storm duration.
Groundwater Recharge
Estimate annual groundwater recharge from precipitation, runoff coefficient, and evapotranspiration using the water balance method.