Evolution of Coastline and Subaqueous Geomorphology off the Survived River Mouth in the Yellow River Delta

Based on the measured data of coastline and bathometry,processed by software of Surfer and Mapinfo,and in combination with sediment load in different phases at Lijin gauging station,evolution of coastline and subaqueous geomorphology off the survived river mouth in the Yellow River delta is analyzed.The results show that ～68% of the sediment delivered by the Yellow River to the sea deposited in the river mouth and littoral area from 1953 to 2000.The changes of coastline in different coasts had a distinctive characteristic in response to transfers of river course into the sea.The coastline was stable in the coasts west of Diaokou river mouth.The coastline from the east of Diaokou river mouth to the north of Gudong oilfield had experienced siltation,and then serious erosion,finally kept stability with the conservation of sea walls.In general,the coastline at the survived river mouth of Qingshuigou river course stretched seaward,whereas the south side of sand spit at Qingshuigou old river mouth eroded after the Yellow River inpouring into the sea near the position at Qing 8.The subaqueous geomorphology off the survived river mouth exhibited siltation from 1976 to 1996,with flat topset beds and steeper foreset beds.From 1996 to 2005,the subaqueous geomorphology off the Qingshuigou old river mouth experienced erosion in the topset and foreset beds,but siltation in the bottomset beds.