Influences of the inclined pressure item caused by salinity - gradient on the flow and those of the deepening of the channel on the invasion of salt water are analyzed by use of a three - dimensional salinity mathematical model for the north channel of the yangtze river estuary 利用长江口北槽三维水流盐度数学模型分析了盐度梯度引起的斜压项对水流的影响,以及航道增深对盐水入侵的影响。