SCS Curve Number Model

The formula:

F/S=Q/(P-Ia)

Therefor,

P=Ia+F+Q

Q=(P-Ia)2/(P+S-Ia), P>=Ia

Q=0 P<

Normally Ia= 0.2

S= 25400/CN- 254

CN ( curve number) value varied depend on hydrological conditions, soil type, land use, vegetation, and crop pattern.

Ia

F

Q

S

P

Time

P

The function was set up from great deal of data test

P: precipitation;

Q: Surface Runoff

Ia: initial loss

F: Current loss

S: Potential loss, = max. value of F

Previous slide

Next slide

Back to first slide

View graphic version