Underwater landforms contour extraction and evolution of Yellow River Estuary

Contours are the primary expression of water depth,they reflect an overall regional underwater landform.The traditional extraction methods are based on existing software and short of automatic degree.Based on the data of the Yellow River Estuary,the methods of interpolating points and extracting contours are discussed.Through analyzing the contour extraction steps and the main idea of ArcGIS Engine,the automatic extraction of contours has been realized in the Yellow River Estuary.It is applied to the Yellow River Estuary geographic information system.Using the method of data analysis,the evolution characteristics of underwater delta near the new mouth of the Yellow River Estuary are studied.The Qingshuigou channel has shifted to the Qing8 branch for more than ten years.The results show that because of the depositing and spreading of the incoming sediment,the landforms of underwater delta near the new mouth has been changed greatly.The underwater delta appears as an oval.The major axis of the oval is about 15km long and the minor axis is about 10km long.It illustrates that when the sediment enters the sea,a great deal of sediment deposits in the new mouth;meantime,the old mouth is scoured acutely,and the thickness of depositing or scouring is less than 1m in the rest region.