In phase 1 dredging engineering of the 12.5 m deepwater channel of the Yangtze River below Nanjing city,the situation of the Tongzhousha channel depth is influenced by the southward movement of the right edge of Kuzigangsha tail,which directly interferes with the dredging operation within area B. Based on the study on water-sand behaviors,bed sand and tidal features and analysis of flow regime and back-silting characteristics,we preset the sediment kerf to mitigate sand flowing from edges into the inner channel. An analysis of the implementation effect of sediment kerf is presented and advices are given to the follow-up construction.