Study On The Modern Trend And Factors Of Change Of Daling River Estuary

Many estuaries in plain always change in their evolution. The changes of most estuaries have similar characteristics, but the changing characteristics of the estuaries vary with different hydrodynamic factors and geographical environments. In this paper, Daling River estuary is selected as the study area. Base on the characteristics of the modern estuary, the changing trend and control factors of the previous estuary have been studied.Daling River Estuary locates in the north of Liaodong Bay. It belongs to the biggest river in western part of Liaoning. According to the historical data, the downstream and estuary of Daling River had changed many times since Ming Dynasty. Affected by the terrain, the changing domain is limited in the east and the south of Linghai city. Linghai city is the vertex in the changing processes. The main changing trend is that the estuary moved to the south in Ming Dynasty. From the late Ming Dynasty to the early 20th century, it moved to the north and then the south again. The change processes indicated the swing characteristics.The factors that influenced the change of the estuary contain the sediment transport and accumulation element and dynamic element. The former which includes the hydrodynamic element is the inducing factor; the latter which includes Coriolis force etc. is the direct factor. The reason the estuary of Daling River moved back and forth since Ming Dynasty was due to dynamic factors.The changes of Daling River estuary have effects on the delta and Panjin wetland. Affected by the change of downstream and estuary, the evolution of delta was limited in the east and the south of Linghai; the development time and the size of the delta is restricted by the changing frequency; the river-sea sedimentation in diifferent periods formed the time range. Because of the complexity of water and sediment sources, there are many controversies over the forming time of Panjin wetland.According to the dynamic factors, the author divided the changing form into the general form and the special form. In the general form, the changes of estuaries are influenced by Coriolis force, and this form is the common change pattern. In the special forms, the estuary overcomes the deflecting move caused by Coriolis force and thus the estuary was pulled to the north. The alternating emergence of the two forms made the Daling River estuary present a to-and-fro movement since Ming Dynasty.