Author(s): Hossein Hamidifar; Michael Nones; Pawel M. Rowinski
Linked Author(s): Michael Nones, Pawel M. Rowinski
Keywords: No Keywords
Abstract: Accurate flood prediction and risk assessment are essential for effective river management, particularly in dynamic alluvial and regulated river systems where sediment transport significantly influences flood behavior. This study investigates the role of sediment dynamics in shaping flood hydraulics and inundation characteristics through two case studies: the Kor River in southwestern Iran and the Middle Vistula River in Poland. For the Kor River, which is regulated by the Mollasadra and Doroodzan dams, sediment transport and deposition processes were incorporated into the HEC-RAS hydraulic model to simulate flood events along a 5.4 km reach upstream of the Doroodzan Dam. Field data on sediment characteristics and hydrological parameters were collected to inform the model. Results indicate that moveable-bed conditions lead to reduced water surface levels compared with fixed-bed assumptions, with sediment deposition and erosion processes substantially affecting flood inundation patterns. In the Middle Vistula River, downstream of the Dęblin hydrometric station, hydrodynamic simulations were conducted under fixed-bed and moveable-bed conditions for floods with 2-, 5-, and 10-year return periods. The results reveal that bed mobility markedly alters flow behavior, with flow velocity increasing by up to 22%, stream power rising by nearly 500% for the 2-year flood, and the Froude number more than doubling for the 10-year event. Despite minor changes in inundation area, flood intensity (defined as depth × mean flow velocity²) increased by up to 85%, highlighting the critical influence of sediment transport on flood hazard characteristics. These case studies underscore the importance of incorporating sediment dynamics and morphodynamic feedback into flood modeling to enhance prediction accuracy.
Year: 2026