Infiltration Formula Based on SCS Curve Number

A formula was developed for computing infiltration in rainfall-runoff simulations from published U.S. Soil Conservation Service soils data. Cumulative infiltration was treated as the difference between cumulative rainfall and runoff. The SCS runoff formula was then differentiated with respect to precipitation to arrive at an infiltration rate with respect to rainfall increments rather than time as used in most previous formulas. A numerical example is included, and two possible refinements are suggested which would involve additional computational labor but should improve the infiltration simulation.