What is SCS Curve Number Method?

The Soil Conservation Service (SCS) Curve Number (CN) is a parameter used in hydrology to estimate runoff potential from rainfall events over a particular area, typically in the context of watershed management and stormwater management.

Developed by the United States Department of Agriculture (USDA) Soil Conservation Service (now known as the Natural Resources Conservation Service or NRCS), the SCS Curve Number method is widely used due to its simplicity and effectiveness in estimating runoff from different land uses and soil conditions.

The Curve Number (CN) represents the combined effect of land use, soil type, and land management practices on infiltration and runoff. It is essentially an index that ranges from 0 to 100, where lower values indicate greater infiltration potential and higher values indicate greater runoff potential.

The SCS Curve Number method uses various factors such as land use, soil type, hydrologic soil group, antecedent moisture condition, and rainfall characteristics to determine an appropriate Curve Number value for a specific area. This value is then used in conjunction with the rainfall intensity and duration to estimate the amount of direct runoff generated from a storm event.

The SCS Curve Number method is commonly used in hydrologic modeling, stormwater management, flood prediction, and watershed planning to assess the potential impacts of land development, land use changes, and storm events on runoff and water quality.


SCS Curve Number



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