A Modified SCS Curve Number Method for Temporally Varying Rainfall Excess Simulation

The SCS curve number (SCS-CN) method has gained widespread popularity for simulating rainfall excess in various events due to its simplicity and practicality. However, it possesses inherent structural issues that limit performance accurately infiltration over time. objective of this study was develop a modified CN with temporally varying intensity (MCN-TVR) by combining soil moisture accounting (SMA) based SCS-CN the SMA Hydrologic Engineering Center’s Modeling System (HEC-HMS). In MCN-TVR, SMA-based is utilized simulate cumulative infiltration, while HEC-HMS serves as an control function. A key advantage MCN-TVR eliminates need additional input parameters inherently linking two methods. Sixteen hypothetical 24 h Type II different types five real Rush River Watershed North Dakota were used assess performances method. simulations, simulated models compared Green–Ampt model. Discrepancies observed between models, especially coarse soils under relatively light rainfall. model, incorporating function, demonstrated improved closer For all events, Nash–Sutcliffe efficiency (NSE) coefficient model greater than 0.99, root mean standard deviation ratio (RSR) less 0.03. applications, failed provide acceptable simulation direct runoff durations time concentration. contrast, successfully NSE values ranging from 0.65 0.91 RSR 0.31 0.56.