The navigation and water flow conditions at the entrance of the inland river estuary are complex.Taking the east extension channel regulation project of the Dalu Line as an example,we use the two-dimensional tidal current sediment mathematical model to simulate the layout scheme,and analyze the influence of different diversion dikes on navigation conditions in complex waters.The results show that the scheme of parallel diversion dike outside the entrance has a certain effect on weakening the cross flow of the outer channel,but the scheme has the problems of increasing the cross flow at the head of the dike,increasing the local cross flow and increasing the amount of siltation,which is not conducive to ship navigation and channel maintenance,and cannot completely improve the navigation conditions outside the entrance,so this scheme is not recommended for the project conditions.The straight curved diversion dikes are arranged at the current siltation-promoting dikes on the south and north sides,which can weaken the cross-flow of some waters at the entrance and the outer channel,optimize circulation flow patterns,and improve the navigation conditions at the entrance,so this scheme is recommended for further study.Considering the effect of the comprehensive scheme and economic factors,it is recommended to set up a straight curved diversion dike with a length of 930 m on the south side and a length of 1 500 m on the north side of the current siltation dike in the south and north of the Dalu Line entrance.