Evaluation of Oasis Stability in Ejina Based on Rough Set and Grey Theory
基于粗糙集与灰色理论的额济纳绿洲稳定性综合评价

Oases are unique landscapes and form the core of human existence and production in arid areas. Oasis ecosystem stability is directly related to regional economic and social sustainable development. Studies of oasis stability are a focus of oasis research, however, the Ejina Oasis has been little studied. Here, we examined the Ejina Oasis and established an evaluation system for oasis stability (natural resources and environment subsystem, socio-economic subsystem, and natural calamity subsystem). A comprehensive evaluation of the oasis was done from 1990 to 2008, looking at the stability of characterization, drive mechanisms, results of previous studies, methods of rough set and the gray theory. The results show that during the observation period the most important indicator affecting oasis stability was water resource class, including the depth of the groundwater (weighting=0.0974), annual precipitation(0.0926) and runoff from Lang-Xin Mountain (0.0902). The number of dust storms, area of desertification, number of windy days, number of frost days and annual evaporation were also important factors. Socioeconomic indicators were the least important (GDP weighting=0.0615; all other factor weightings less than 0.05). The stability of the Ejina Oasis fluctuated from 1990 to 2004, and followed a steady upward trend from 2005 to 2008. The value of the oasis stability index showed a downward trend from 1990 to 2000, and then a clear upward trend from 2001 to 2008. The oasis stability index was lowest in 1992 and 2001 and highest from 2005 to 2008. Oasis stability is dependent on multiple complex factors in which a single indicator can affect oasis stability only in certain aspects. Our findings indicate that a more comprehensive strategy should be developed to restore the ecological environment of the Ejina Oasis.