Investigation of Flow Reformation and Deformation Processes in the Junction Zone of Two Open Channels at Different Angles

The hydrodynamic characteristics and channel bed deformation in the confluence zone of two alluvial open channels at different junction angles were studied using laboratory experiments, theoretical modeling, and field observations at the Mirishkor irrigation canal in Uzbekistan. The formation and dimensions of the main flow zones (stagnation, shear layer, separation, recirculation, and recovery) were identified. The results show that the size of the recirculation zone at different angles is approximately 20–30% smaller compared to larger angles, and the flow recovers more rapidly. For vortex-free zones, the potential flow theory and conformal mapping method were applied to determine the streamlines boundaries. Improved empirical equations were developed for the parameters of the recirculation zone, velocity distribution, and bed sediment transport as functions of the junction angle θ and discharge ratio Qr. Hydraulic calculation algorithms that account for vortex effects improved prediction accuracy and enabled an increase in channel conveyance capacity by 5–8% in practical applications. These findings provide practical tools for reducing deformations in irrigation networks.