Abstract: Huangcao Gorge is located approximately 9km downstream of Changshou District of Chongqing City. Torrent flow and over-ledge current are formed in the lower reach at Huangniu ridge (the left bank) when the water level exceeds 162m. The safe navigation (especially upward navigation) is affected and the navigation cycle is shortened by this flow regime. To improve the navigation condition, we analyzed the water depth and flow pattern in the navigation channel, and proposed two schemes of rock blasting and demonstrated them by establishing 2-D mathematical models (with measured water level and flow as control conditions). By analyzing the computation results, we concluded that both the schemes could meet the requirement, but scheme 1 (simple blasting to the designed elevation) is cost-saving but couldn’t enhance the navigable flow condition much; whereas scheme 2 (by cutting slope and blasting the rock platform at 159-163m) effectively improves the flow condition. Measures should be taken according to specific requirements and budget conditions.

Key words: Huangcao Gorge, channel regulation, mathematical model, comparison and selection of schemes