Document Type : Original Article
Authors
1
Department of Civil Engineering, Najafabad Branch, Islamic Azad University, Isfahan, Iran.
2
Department of Civil Engineering, Isf.C., Islamic Azad University, Isfahan, Iran3
3
Department of Civil Engineering, Najafabad Branch, Islamic Azad University, Najafabad
10.22034/hyd.2026.74322.1867
Abstract
Following the collection of climatic, hydrological, and hydraulic data for the study area, an initial model was developed using the Storm Water Management Model (SWMM). A sensitivity analysis of the model parameters was conducted based on five measured rainfall–runoff events. The model was then calibrated using three measured events and validated using two independent events. Model performance was evaluated through visual comparison of simulated and observed hydrographs and by calculating the Nash–Sutcliffe efficiency (NSE), root mean square error (RMSE), and coefficient of determination (R²). Finally, following calibration and validation, the hydrological performance of the drainage network was evaluated under rainfall events with different return periods.
The sensitivity analysis showed that flow width, Manning’s roughness coefficient of the channels, roughness of impervious areas, and mean slope had the greatest influence on model performance. The model showed satisfactory agreement with the measured data. For the three calibration events, NSE values were 0.79, 0.66, and 0.71; RMSE values were 0.20, 0.73, and 0.10; and R² values were 0.92, 0.87, and 0.88, respectively. For the two validation events, NSE values were 0.74 and 0.66, RMSE values were 0.78 and 0.55, and R² values were 0.90 and 0.86, respectively. Drainage network simulations showed that 2, 6, 7, and 8 channels experienced flooding under the 2-, 5-, 10-, and 25-year return-period rainfall events, respectively. These findings indicate that several secondary channels have insufficient conveyance capacity under design rainfall conditions, highlighting the need to improve their hydraulic capacity and implement targeted management measures in critical areas.
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