The dual-nuclei structure composed by ACD and the gateway city has been developing along with the evolution of physical environment of delta, which could be divided into five phases.

• 在内河航运向海运转变过程中，三角洲与区外交流的门户由顶点区域转移至沿海地区，三角洲顶点城市地位逐渐下降，以至落后于门户城市。