Abstract:

The Sanxia (Three gorges)Danjiangkou Region and its adjacent Area are，in the area of the middle line for diverting the Yangtze River to the Han River in the SouthtoNorth Water Transfer Project.Fuzzy mathematical method (FMM) was applied in the quantitative assessment of the crust stability of the region，with the priority given to structure stability.The ground stability was also considered.16 indexes such as geological and earthquake activity fault，crust deformation，geological disaster were selected.The power value for each index was confirmed through expert system in order to ensure the rationality of the assessment.It is revealed that the region has 3 sections of relatively less instability，15 sections of relatively hypostability，8 sections of relative stability.Meanwhile，the reliability and limit of the mathematical method were also discussed in this paper.It is shown that the selection of the indexes and their power value are very important for the results and the results obtained at present is of significance for future management of the Three Gorges Project，and will be of reference values for selecting the waterline for diverting the Yangtze River to the Han River.

Key words: Sanxia (Threegorges)Danjiangkou Region, crust stability, fuzzy mathematical method, Diverting the Yangtze River to the Han River