Ecological Security Evaluation Of Coal-mining Supported City Based On PSR Model

In recent years, the traditional coal-mining supported cites in China have been gradually turning into resource-exhausted city, and their ecological environment is much more sensitive and fragile than that of common cities. How to make the new coal-mining supported cities to obtain higher degree ecological security and not to follow the traditional way of ecological damage is an urgent task for those new coal-mining cities to solve.Based on Pressure-State-Response (PSR) model, this paper built an evaluation index system of ecological security evaluation with 4 layers which are target, criteria, factor and variable for coal-mining supported cities. To be concrete, the index system included 3 criteria which were pressure, state and response,8 factors which were population pressure, society and economy development pressure, resources capacity pressure, environmental pollution pressure, resoures state, environment state, environmental governance response and investment response, and 33 variables including the mortality of million tons of coal, mining of industrial added value, energy consumption per 10000 yuan GDP and so on.Analytic hierarchy process (AHP) was chosen as the subjective method, and entropy method(EM) as well as optimization method(OM) were used as the objective ways of weight, and then based on those three kinds of weights, a comprehensive weight model was been established with the overall consideration of subjective and objective iterms. The calculation results showed that the mortality of million tons of coal, sulphur dioxide emission intensity per 10000 yuan GDP, times of sadstorm per year, the treatment rate of industrial emissions, the percentage of environmental investment in GDP shared larger weight.Taking Erdos city as an example, a dynamic assessment of ecological security from 2003 to 2008 was undertaken on the basis of the comprehensive index method. Besides, an analysis of key influencing factors was given by the method of principal component analysis. The results of this research are listed as follows:(1) The ecological index of Ordos city from 2003 to 2008 was improved year by year, and its situation became better and bertter. However, the overall ecological security of Ordos city was not very good, and its average level was in the third place which was an sensitive situation. The poor situation was ascribed to larger pressure as well as fewer responses. (2)The protential factors of insecurity in Ordos were as follows:too low rate of tertiary industry in GDP, large proportion of mining in industrial added value, the energy consumption per 10000 yuan GDP, th sulphur dioxide emission intensity per 10000 yuan GDP, the emission of industrial wastewater and soli waste were higher that the ideal level, and environmental investment was far inadequate.