Abstract:The distributions of hydraulic parameters in the gate chamber change due to flaring gate piers (FGPs). The variations in water level and velocity were analyzed quantitatively using RNG k-εturbulent model. The extent of water level rising on side walls with X-shaped FGP increased from zero to 0.2 during the first 75% of gate chamber, and it grown rapidly during the last 25%. The extent of water level rising with Y-shaped FGP was slightly higher than that with X-shaped and the difference rised during the last 25% of gate chamber. The FGP decreased the velocity gradient in the middle part of gate chamber and the Y-shaped FGP impacted the gradient stronger than X-shaped. FGPs made changes for both the direction and magnitude of velocity in the outlet. The distribution of velocity assumed extremely non-uniform, especially the significant change of direction and the great increase in the horizontal velocity (compared to ordinary pier). The extent of water level rising is a reference for the arrangement of hinge supports, and the quantitative analysis on the velocity is helpful for understanding the longitudinal and vertical developments of flow.