Assessing the Hydraulic Resilience of Natural, Open-Channel and Covered-Channel Floodways under Extreme Flood Events: A Case Study of the Abkharar Watershed, Iran

اصغری پری, سید امین; صحرایی, بهنام; عمادعلی, لطف اله

doi:10.22126/atwe.2026.14147.1223

Assessing the Hydraulic Resilience of Natural, Open-Channel and Covered-Channel Floodways under Extreme Flood Events: A Case Study of the Abkharar Watershed, Iran

نوع مقاله : مقاله پژوهشی

نویسندگان

¹ گروه عمران، دانشکده فنی و مهندسی ، دانشگاه صنعتی خاتم الانبیا بهبهان

² Department of Civil Engineering, Faculty of Engineering, Behbahan Khatam Alanbia University of Technology, Behbahan, Iran

10.22126/atwe.2026.14147.1223

چکیده

Urban flood-control channels are increasingly being covered to support urban development and improve land-use efficiency. However, the hydraulic consequences of such interventions under extreme flood conditions remain insufficiently understood. This study evaluates the flood conveyance performance of the Abkharvar floodway in Behbahan, southwestern Iran, using an integrated HEC-HMS–HEC-RAS modeling framework. Design rainfall events with return periods of 2–200 years were estimated using the Generalized Extreme Value (GEV) distribution. Runoff hydrographs were generated in HEC-HMS, and hydraulic simulations and flood-hazard mapping were performed using HEC-RAS and GIS tools. Three scenarios were analyzed: natural-channel conditions, the existing engineered open channel, and a proposed covered-channel configuration. Simulated peak discharges increased from 1.40 m³ s⁻¹ for the 2-year event to 4.60 m³ s⁻¹ for the 200-year event. Results showed that the existing channel provided the most balanced hydraulic performance, whereas the covered-channel scenario generated stronger backwater effects, higher water levels, and greater overtopping potential during extreme floods. Flood depths reached approximately 0.8–1.5 m under the 100-year flood in the existing channel and up to 3 m in critical covered sections. Flood-hazard mapping identified channel contractions, bridge crossings, and covered-channel transitions as the principal hydraulic bottlenecks controlling system performance. The findings demonstrate that channel covering may reduce hydraulic resilience despite its urban-development benefits and highlight the importance of integrated hydrological–hydraulic assessments for sustainable urban flood management.

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