Relation Between Curve Number and Runoff Coefficient

Abstract

The rational method is probably the one most widely used for estimating peak discharges for inlet designs on small watersheds. The basic input requirements include the drainage area, a rainfall intensity for the design return period, and a runoff coefficient (C). The Soil Conservation Service TR-55 graphical method is another widely used technique for estimating peak discharges for small drainage areas. Input includes the drainage area, the 24 hr precipitation depth for the design return period, the runoff curve number, and the time of concentration. The objective of this study is to demonstrate that the two runoff indices are related.