The performance and efficiency of irrigation canal systems are critical for sustainable water resource management in agricultural regions. This study investigates overtopping flow in a dual-channel irrigation canal separated by an earthen embankment, under four vegetation configurations: bare, tall vegetation, short/submersible vegetation, and alternating vegetation strips. CFD simulations were conducted in ANSYS Fluent to model the hydraulic behavior for each scenario. A novel image-based method was developed to extract overtopping discharge,head loss, and percentage reduction directly from CFD velocity contours when numerical export files are unavailable. The method was validated against analytical weir-based calculations.

Results show that the tall vegetation reduced overtopping discharge by approximately 61%, short vegetation by 33%, and alternating vegetation by 22% compared with the bare case, demonstrating the significant influence of vegetation arrangement on inter-channel flow control.

This work introduces a practical, image-based quantification method for overtopping discharge and hydraulic losses in CFD-modeled irrigation canals. Unlike prior studies dependent on field measurements, raw data exports, or purely analytical models, the proposed method enables reliable parameter extraction from simulation images alone. The study further provides a comparative evaluation of three vegetation layouts under identical hydraulic and geometric conditions, offering new insights into their relative effectiveness for overtopping mitigation.