Hydrological Modeling and Flood-Generating Sub-Basin Prioritization Using HEC-HMS in the Kalan Dam Watershed

Bashirgonbad, Mohammad; Jafari, Shadi

doi:10.22059/ije.2026.408949.1903

Hydrological Modeling and Flood-Generating Sub-Basin Prioritization Using HEC-HMS in the Kalan Dam Watershed

Articles in Press

Document Type : Research Article

Authors

¹ Department of Nature Engineering, Faculty of Natural Resources and Environment, Malayer University, Malayer, Iran

² M.Sc. in Watershed Management, Department of Nature Engineering, Faculty of Natural Resources and Environment, Malayer University, Malayer, Iran

10.22059/ije.2026.408949.1903

Abstract

Floods are the most devastating natural disasters, making the accurate quantitative and qualitative identification of their source areas crucial for effective management. Hydrological models, capable of the rainfall-runoff process, provide a distinct advantage over purely empirical methods by enabling the precise delineation of critical flood-generating zones. This study aimed to identify and prioritize such areas within the Kalan Dam watershed using the HEC-HMS hydrological model. The model simulated peak discharges utilizing data from ten distinct rainfall-runoff events. Calibration and validation were performed using the Simplex algorithm. For the selected calibration event (February 26, 2020), performance was evaluated as excellent, with an NSE of 0.947, RMSE of 0.2, and PBIAS of 8.56%. The results demonstrated that while larger sub-watersheds contribute a greater absolute peak discharge, prioritizing intervention based on specific discharge yields a markedly different ranking. Analysis revealed sub-watershed W530, with the highest specific discharge of 0.156 m³/s/km², as the top priority for implementing watershed management measures. Conversely, sub-watershed W860, with the lowest specific discharge of 0.144 m³/s/km², was assigned the lowest priority. These findings underscore the critical importance of incorporating qualitative and specific hydrological metrics, beyond simple areal extent, for targeted and efficient flood risk mitigation.

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