Abstract:Gongqiaogou reaches is a pebble shoal during dry season and a brook outlet rapids during middle and the flood period on the end section of Xiangjiaba Reservoir during subsidence period,and the Fotan is a narrow channel type rapids in pre-flood falling stage of the reservoir.The two beach are close in distance and the navigation environment is relatively complex.On the basis of the relevant research on the beaches carrying capacity of ships in the Yangtze River and Jinsha River,the allowable value of the comprehensive judgment E for beach clearance is fitted.According to the characteristics of rapids and navigation obstruction,the measures are adopted such as clearing obstacles to increase the channel scale and increase the discharge area of the Gongqiaogou reaches,and removing protruding reefs at the entrance of the Fotan rapids to smooth the water flow.The regulation effect of waterway engineering is analyzed and evaluated by actual ship seaworthiness test and mathematical models calculation.The mathematical model calculation results show that,the E value of hydraulic parameter of rapids abating of the Gongqiaogou reaches decreased from 0.60 to 0.48 m at 6,000 m3/s during the subsidence period after regulation,and the Fotan rapids decreased from 0.71 to 0.62 m,and the flow diversion is slowed down.Under the actual ship seaworthiness test conditions,the ships can safely pass through the regulated river section,indicating that the regulation effect of the waterway engineering meets the design requirement.Taking into account the navigation conditions of the river section near the Xiluodu Dam,it is recommended that the restricted discharge during the subsidence period of this river section is 7,000 m3/s.
