Deficiencies in the Curve Number Method

Abstract

This study investigates the relationship between the curve number and regional rainfall characteristics, and also determines the extent to which intrastorm application of the curve number method is likely to generate infiltration rates that exceed the infiltration capacities of catchment soils. It is shown that there is a sufficiently strong relation between the curve number and regional rainfall characteristics in the US that precludes translating curve numbers between locations based only on land cover, land use, and hydrologic soil group. It is also shown that intrastorm application of the curve number method is valid only for relatively high curve numbers, thereby limiting the application of the curve number method for calculating intrastorm runoff rates.