The Curve Number (CN) method is a widely used method in hydrology to estimate the amount of stormwater runoff from an area. The CN method is based on the characteristics of the land use, soil type, and antecedent moisture conditions of a particular area. The CN method is commonly used in the design of stormwater management systems, flood control projects, and watershed modeling.

Note that the CN values used in ArcGIS Pro are typically taken from tables or equations that are based on empirical data. The specific CN values used will depend on the land use, soil type, and antecedent moisture conditions of the area being analyzed.