| The South Yellow Sea radial sand ridges are huge sediment body on the continental shelf. It is located in the offshore of the Jiangsu Provinces. It is concerned by the huge scale, the unique shape, complex reasons and changeful hydrodynamic conditions. In this century, seaport development proposed stability studies on the radial sand ridges.The comprehensive material gain of the radiate sand ridge filed is difficult. At present there is no data that cover the range of the radiate sand ridge filed late in 1979. According to the need, the latest data of the tidal channel of Xiyang and Jiangjiasha which is measured in 2006 collected from 908 Special Investigation. The scale of the chart is 1:100,000. The latest data of the tidal channel of Lanshayang and Huangshayang which is measured in 2005 collected from the Yangkou port. The scale is 1:75,000. The old data of the whole filed which is measured in 1963-68 and 1979 collected from the the Marines Sailing Assurance. The scale of the chart is 1:200,000.The basic data which is measured data collected from the Marines Sailing Assurance and 908 Special Investigation. The basic data is true and correct. The remote sensing inversion water depth data collected from the 908 Special Investigation is inaccurate, which can be proofed by the method of overlay analysis.Currently, the study about Xiyang tidal channel and Lanshayang and Huangshayang tidal channels is increases gradually, but the research about the Jiangjiasha tidal channels does not change. This paper is in the background of the whole radial sand ridges. Using Geographic Information System (GIS) means, through the establishment of digital elevation model to overlay analysis the depth data and get the whole erosion and deposition result from 1963-68 to 1979 and get the erosion and deposition result of tidal channels of Xiyang and Jiangjiasha from 1963-68 to 1979, from 1979 to 2006 and get the erosion and deposition result of tidal channels of Lanshyang and Huangshayang from 1963-68 to 1979, from 1979 to 2005. The aim of the paper is to know the stability of the field and the change trend in the future.The result is:(1) It is showed that from 1963-68 to 1979 the coastwise and northeast of the radial sand ridges being depositing, and the variation of the hub department in the radial sand ridges is frequent, and the most part of the outside sea is stable. The volume of depositing being+2.38×109m3, and the net erosion and deposition rate being +0.01m/a,which is little.(2) It is concluded that from 1963-68 to 1979 the Xiyang tidal channel is in natural erosion state. The net erosion and deposition rate being-0.011 m/a. The erosion in the east channel is stronger than in the west channel and wave flow erosion effect is remarkable. From 1979 to 2006 Xiyang tidal channel is still in the erosion state and even enhanced. The net erosion and deposition rate being 0.016 m/a.(3) From 1963-68 to 1979 the overall of the tidal channel of Lanshayang and Huangshayang tidal channels present erosion and deposition dynamic balance of trend. The net erosion and deposition rate being+0.085 m/a. From 1979 to 2005, the tidal channels in paragraph deepening, tidal channel more forming.(4) From1963-68 to 1979 the overall of the tidal channels of Jiangjiasha present erosion and deposition dynamic balance of trend. The net erosion and deposition rate being-0.008 m/a. From 1979 to 2005, the volume of the erosion and deposition of the tidal channels is stronger, which is the same to the area of the erosion and deposition of the tidal channels. The net erosion and deposition rate being+0.011 m/a. The research results can be directly applied in Jiangsu coastal development, portconstruction and land reclamation work, which have important scientific value.
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