A Modified SCS-CN Method: Characterization and Testing

The Soil Conservation Service Curve Number (SCS-CN) method (SCS,1956) is modified by accounting for the static portion ofinfiltration and the antecedent moisture. A volumetric analysisshows that the ratio of the potential maximum retention (S) tothe precipitation amount versus the runoff factor relation isequivalent to the average suction pressure-moisture contentrelation for a unit rainfall amount and a given soil porosity. Asimple spreadsheet procedure is suggested for determining S withuse of a 5-day antecedent precipitation amount. The modifiedmethod is found to perform well on the same data sets as used inthe National Engineering Handbook (SCS, 1971). Copyright Kluwer Academic Publishers 2003