Visualization of River Channel Evolution of the South Branch in Yangtze Estuary Supported by GIS

Supported by GIS, several of charts of the South Branch of Yangtze estuary from 1900 to 2001 was digitized and Digital Elevation Model (DEM) of channel was established, based on which evolution of it since 1900 was visualization. The results show that: (1) DEM is an effective means for visualization and quantitative analysis of the channel evolution. (2) From 1900 to 2001, the channel storage volume in the south branch of Yangtze river slightly increased with an average annual increment of 2.7 million m3 at the depth of 0m; the entire river area was characterized by mild erosion, with the average annual erosion volume of 3.3 million m3 and average annual erosion thickness of 0.37 cm (including artificial dredging and reclamation as well as dredging amount). (3) The erosion and deposition state varied in different sections and at different time. Before 1958 and after 1979, the channel was characterized by erosion and expansion, while it was marked by deposition from 1958 to 1979; the erosion and deposition in the section of the entrance and exit of the channel in the south branch varied more violently than that in the middle section of the channel.