Curve-Number/Green-Ampt Mixed Procedure for Net Rainfall Estimation: A Case Study of the Mignone Watershed, IT

A mixed procedure, referred to as CN4GA (Curve Number for Green-Ampt), was recently introduced with the aim of distributing in time the net rainfall volume provided at event scale by the Soil Conservation Service - Curve Number (SCS-CN) method. The proposed method consists in employing the Green-Ampt infiltration equation and calibrating both the ponding time and the soil hydraulic conductivity using the initial abstraction and the total volume given by the SCS-CN method. The procedure is here applied on several rainfall-runoff events observed in an Italian watershed. Results confirms the general behavior already noticed in previous studies: the CN4GA procedure provides net rainfal intensities consistent with the runoff observations, the SCS-CN method underestimates peak intensity when applied at sub-daily* resolution, and the differences between the two approaches are relevant when the gross rainfall peak occurs at the beginning of the storm and generally in case of multi-peak events.