Since the Three Gorges Reservoir was impounded to 175 meters,the conditions of the navigation channel in the upper reservoir section of the Yangtze River have been greatly improved.However,the navigation channel in the tail section of the reservoir still has many reef obstruction problems during the flood season.Remedial measures need to be taken to improve navigation conditions.Taking Heshangtan,a staggered rapids in the upper reaches of the Yangtze River from Fuling to Fengdu,as an example,aiming at the problem of navigation obstruction during the flood season,the causes and characteristics of navigation obstruction are analyzed by collecting actual measurement data and combining it with a two-dimensional water flow mathematical model.On this basis,corresponding rectification plans are proposed and the rectification effects are analyzed.The results show that by taking remedial measures to remove the reefs at Heshangtan on the right bank and Guojiazui on the left bank,adverse flow pattern problems such as rapid flow speed in the flood season at Heshangtan strong cross currents at the front of the reefs,and strong backflow behind the reefs can be effectively improved.The research results can provide technical support for the improvement of the staggered-mouth rapids in the tail section of the Three Gorges Reservoir.