通过对上海国际航运中心洋山深水港所在崎岖列岛海域水、沙运动规律和冲淤环境的调查研究，对港口建设过程中小洋山岛链3个汊道的封堵而导致汊道潮流量的丧失，港区淤积体的生成，进而引起洋山港区海床地形冲淤环境变化的过程进行了深入分析。认为堵汊工程后，在新的边界条件下，经过水沙和地形冲淤的不断调整，原来“冲淤平衡、略有冲刷”的环境逐渐得到恢复，港内水深得到良好维护，确保了深水港的成功建设。

On the basis of survey of the movement law of watersediment and erosion and sedimentation environment at Qiqu Archipelago area where the deepwater harbor of Shanghai International Navigation Center lies, such problems as the lose of tidal discharge at bifurcations, the formation of sedimentation on sea bed at harbors and the change of erosion and sedimentation environment at Yangshan area, which were caused by the construction of dams at three bifurcations along Qiqu Archipelago, are studied in this paper. It is concluded in the paper that new situation has come into being after the construction of dams at bifurcations. As a result, the movement of water current, suspended sediments, and the erosion and sedimentation environment have been adjusted, previous balance between erosion and sedimentation will be resumed, the depth of the harbor will be kept well and the deepwater harbor will be constructed successfully.