近30年来长江河口南港冲淤变化与微地貌特征

The study investigated micromorphology of the South Channel of the Yangtze River Estuary using multi-beam bathymetric data measured during February 2015.Digitized bathymetric data during 1992~2019 were also used to access long-term morphological changes of the riverbed and how the changes were affected by human activities.Results show that the channel bed changed from aggradation during 1992~2002 to degradation during 2002~2019 due to significant decrease of sediment supply caused by the Three Gorge Dam.There are three common bedforms in natural rivers in the South Channel(i.e., smooth surface, gully and dune).We found two micromorphology usually formed under human intervention which are hollow and dredging marks.The average length, height, and height to length ratio of the dunes are 21.5, 0.91, and 0.06m, respectively.The bed roughness(Ks) associated with the dunes is 0.65.Severe channel erosion and coarse sand supply may contribute to the growth of the dunes and the downstream movement of the dune zone.