Experimental Study of Hydrodynamics of Inbank and Overbank Flows in Meandering Compound Channel

Considering the meandering pattern of most rivers in the world and the complicated behavior of the flow within them, studying the hydrodynamics of the flow is necessary due to the occurrence of floods and the spread of the flow from the main channel to the floodplains, causing significant damages. In this study, the hydrodynamics of flow in a meandering compound channel with a sinuosity of 1.3 considering the flow conditions of inbank and overbank flow with a depth and relative depth of 0.12 m and 0.46 respectively, have been analyzed experimentally. Velocity components were measured by an ADV (Acoustic Doppler Velocimetry) velocimeter at six cross sections. The results showed that the magnitude of the longitudinal velocity increases with decreasing relative depth, and the longitudinal velocity in the inbank flow is increased by 30%- 45% compared to the overbank flow. Observing the changes in the transverse velocity of the inbank and overbank flows, it can be seen that with the 92% increase in the depth of the flow, the values ​​of the transverse velocity of the flow have decreased by about 60% in the overbank flow. Core vertical turbulence intensity is $$\:\frac{{w}_{rms}}{{U}_{0}}>0.2$$ for inbank and overbank flows. The maximum position of the secondary flow power in the inbank and overbank flows occurs at a distance from the bed up to 50% of the flow depth. The findings of this study enhance our understanding of turbulence characteristics and flow resistance, river dynamic management and floodplain behavior. The results provide valuable information for flood risk management, identification of areas prone to erosion, sedimentation and erosive forces, the design of hydraulic structures, infrastructures and coastal protection.