In this study, virtual confluence of 30°, 45°, 60°, 75° type flowing into main channel was designed to comprehend
occlusion phenomenon of the mouth of river, then performed numerical analysis using the RMA-2 and SED2D model of
SMS according to application of 40m, 60m, 80m, 100m Training levee corresponding to main channel width ratio. Results
of simulations analysis are summarized as follows. Applying appropriate Training levee length determined by numerical
analysis results, Training levee dimension for occlusion reduction was studied through the analysis of velocity, water level,
bed variation at the Gamchen confluence and Wichen confluence.