Abstract:

Frequent occurrence of water environmental vulnerability is induced by intensifying shortage of water resource,water environment pollution,drought and flood disasters,and ecoenvironmental deterioration. Studies on the vulnerability of water environmental system have become more and more important. Recent works pay attentions mainly to groundwater environmental vulnerability,water resource vulnerability,water environmental carrying capacity vulnerability and water inrush vulnerability. It's unilateral to study on the water environmental system vulnerability from a sole aspect. It is necessary to study the vulnerability from a combination of water resource,water environmental quality,drought and flood disasters,social,economic and ecoenvironmental aspects. According to the characteristics of the water environmental system vulnerability which is sensitivity response of system status to  pressure,the index system of the regional water environmental system vulnerability is built up based ona pressurestateresponse model. The water environmental system is a complex system involving regional water resource,the quality of water resource,drought and flood disasters,social,economy and ecoenvironment. Many uncertainties caused by discrepancy degree coefficient are uncertain while the uncertainties with connection number in regional water environmental system vulnerability are described. So there are many uncertainties in the research on the regional water environmental system vulnerability. In the process of using a connection number to describe the vulnerability,there is still uncertainty in the difference degree coefficients within ［-1,1］. Structural triangular fuzzy numbers are proposed to characterize the uncertainty of difference degree coefficient value,according to the expectation and square difference method for priorities of connection numbers with confidence level α.The decision analysis model is established using connection numbers of triangular fuzzy number. The model is applied for vulnerability assessment of water environment in Anhui Province. The results show as follows:(1)The vulnerability ratio of regional water environmental system in Anhui Province is between ［2731 3620］,ranking the cities as follows,Chizhou,Huangshan,Anqing,Tongling,Xuancheng,Wuhu,Lu'an,Hefei,Maanshan,Chaohu,Chuzhou,Huaibei,Fuyang,Bengbu,Huainan,Suzhou,Bozhou. According to the distribution of the water environmental system vulnerability in Anhui Province,the stronger vulnerable regions,for example,Bozhou,Suzhou,Huainan,are located in the plain of Northern Anhui. The vulnerability of regional water environment system is high because of the lack of water resources in plain area,mainly to the agricultural production,social and economic development relatively backward. The vulnerability of regional water environment system in riverside area is low because of the relatively abundant water resources,more developed social economy,and larger cost of water environmental treatment or protection,which is a larger role in the improvement of the situation of the water environment.(2)The index system of the regional water environment system vulnerability with clear concept,relatively independent connotation,and no conflict,overlap among the indexes,is scientific and practical.(3)The difference degree coefficient is described by the policydecisionmaking model of the regional water environment system vulnerability based on the structural triangular fuzzy numbers. The uncertainty in standard node of the vulnerability index values of the regional water environment system can be effectively described