Enhanced Runoff Curve Number Model Incorporating Storm Duration and a Nonlinear Ia-S Relation

Incorporating the storm duration and a nonlinear relation for initial abstraction (Ia) , this paper presents an enhanced version of the Soil Conservation Service curve number-based Mishra–Singh model. The proposed version is compared with existing formulations using a large set of storm rainfall-runoff events derived from the water database of the United States. The results of the paired t -test of related samples and standard error of estimate (Se) statistic comparison of split sampling-based calibration and validation and simulation on full data set show that the proposed version performs far better than all other existing versions.