Flood hydrograph simulation using the SWMM model: A semiarid zone watershed case study, Shiraz Khoshk River, Iran

In the past few decades, considerable efforts have been made to model rainfall‐runoff and to predict the hydrological impacts of various factors using computer technology. The Environmental Protection Agency Storm Water Management Model (SWMM) has been proved to be a powerful tool which simulates the flow of watersheds with different characteristics. The SWMM model is a dynamic rainfall‐runoff simulation model used for single event and/or continuous runoff simulation. It is widely used throughout the world for analysis, planning, and design related to storm water of drainage systems in urban areas, with many applications in nonurban areas as well. This study aimed to assess the performance of the SWMM model for flood simulation in the Shiraz Khoshk River originated from an arid zone watershed. The study area with a combination of natural and urban watersheds (900.3 km2) is located in South‐West of Iran in Fars Province. In this study, the model was calibrated using 12 flood events recorded at the Eghbal‐Abad gauge station. Then, for validation, 10 and 4 other hydrographs were simulated for the Nahre‐Azam and Chenarsukhte gauge stations, respectively. The calibration and validation results show a good agreement between the observed and simulated flows (R2 = 0.96 for the calibration, 0.91 and 0.87 for validation). The model performance criteria were plausible (e.g., Nash‐Sutcliff coefficient = 0.91 for calibration; and 0.88 and 0.86 for validation). Therefore, the results indicate the high efficiency of the model to simulate the flow in this watershed, useful for predicting the impact of various management scenarios on flow characteristics. Recommendations for resource managers The SWMM model can be successfully applied to semiarid zone watersheds. The model is suitable for urban and nonurban watershed simulations.