Historical Changes of Coastlines on West and South Coasts of Bohai Sea since 7000 a B. P.

The coastal lowland between the Holocene transgression extreme and present coastline is prograded by several river deltas: the Luanhe River Delta,old Yongding River-old Chaobai River Delta,old Ziya River-old Daqing River Delta,Haihe River Delta,Huanghe(Yellow) River Delta and Weihe River-Mihe River Delta.The change of the coastline is controlled by evolution of these deltas: progradation in the active stage of the delta lobe or delta superlobe,retreat in the early time of the abandoned stage and then stabilization.The tremendous sediment discharge of the Huanghe River results in shifting of the delta superlobe and projection of the local coastline.