Analogy Between SCS-CN and Muskingum Methods

Soil Conservation Service Curve Number (SCS-CN) method is one of the most widely used, popular, stable, reliable, and attractive rainfall-runoff methods, initially designed for direct surface runoff estimation in small and medium agricultural watersheds. It, in various forms, is now being employed to several areas other than the intended one, such as infiltration, sediment yield, pollutant transport and so on. In this study, the proportionality concept of the SCS-CN method is further extended to the field of flood routing and is shown to either parallel or be analogous to the Muskingum routing method, which is a simplified variant of St. Venant equations. When employed to various real (typical) flood events of four different river reaches available in literature from different sources, and thus, of varying flow and channel settings, the results of SCS-CN concept compare well with those due to Muskingum method in terms of their evaluation for performance through root mean square error (RMSE) for overall hydrograph, and relative error (RE) for peak discharge (Qp) and time to peak (Tp) of all four flood events. It thus underscores not only the efficacy but also the versatility of the SCS-CN concept in application to one more field of flood/flow routing, which forms to be an element of paramount importance in distributed hydrologic modeling.