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Stability of the tidal flat in silt-muddy coast is the ability to keep its terrain from erosion under the ocean dynamic
processes. Evaluating the stability of the tidal flat is one of the most important issues insediment dynamics research field
, and has been attached more and more importance. Dongsha Sandbank is one of the largest sandbanks of the radial sand
ridges, and serves as an important barrier to the inner sandbank and has a direct impact on the process of Tiaozini
Sandbank merging into mainland. To evaluate the stability of Dongsha Sandbank will provide guidance for coastal zone
environmental protection (such as environmental protection and coast protection, etc.) to make a rational use of tidal flat
resources for sustainable development. In the study, 63 scenes of remotely sensed imageries from 1973 to 2007 were
collected, taken by different sensors such as MSS, TM, ETM+, SPOT, ASTER and CBERS. GIS & RS technology was
used in the stability analysis of Dongsha Sandbank tidal flat based on field investigation, RS classification and overlay
analysis. Major relate factors such as sediment dynamic environment, tidal channel and tidal creek system were
discussed in the paper. Some conclusion can be summarized as follows :( 1) Integral stability of Dongsha Sandbank tidal
flat has been gradually declined from 1973 to 2007. This trend was embedded in two aspects: both area of stable tidal flat
and maximum value of stability coefficient degraded. (2) Tidal flat with high stability is mainly distributed on the sand
ridges of Dongsha Sandbank, and has an integrally contractive trend: in the mid-continental region, one region with high
stability coefficient has been broken into two small parts-- the northern part has a southwards movement while the
southern has a northern wards movement; within the north part, stability of the tidal flat reduced with the northwards
movement of the shoreline; in the west part, the tidal flat is in an unstable state due to the lateral swing of Xiyang Tidal
Channel and strengthen of tidal creek activity; and in the south part, the tidal flat has a low stability due to the unstable
flow path of Doufuzhayaomen Tidal Channel.
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