Origin of Coastal Landforms From the Zhangweixin River Mouth to the Tuhai River Mouth Along the West Coast of the Bohai Sea

The coast from the Zhangweixin River mouth to the Tuhai River mouth along the west coast of the Bohai Sea was stable and showed a straight coastline during the period of 1128—1904. The distributary channel of the Yellow River shifted to the east of the Tuhai River mouth and the land expanded to the north. A bay was gradually formed during 1904—1929. While the distributary channel of the Yellow River shifted to the middle of the Yellow River delta during 1934-1976, the land expanded further to the north and a wide "V"-shaped open bay was finally formed from Qikou of Hebei Province to the middle of the Yellow River delta. The Tuhai River mouth is just located at the apex of the wide "V"-shaped open bay. The coast from the Zhangweixin River mouth to the Tuhai River mouth is close to the apex and faces to the northeast strong winds, which occasionally induces strong storm tides. Comparing with those before 1904, the tidal range increases, the spring high tide level becomes higher, and much higher water level occurs in the storm tides. The storm tides and waves result in strong erosion, coastline retreat, very developed tidal channel system and remnant alluvium islands in the supratidal zone.