基于GIS的北京地区生态风险评价

Ecological risk assessment in Beijing based on GIS

生态风险评价是目前环境科学领域的研究重点,而水土流失问题是造成生态风险的主要因素。以生态风险评估理论研究为基础,将该体系按照生态危险性、生态重要性和生态易损性3部分进行分析,以北京市的遥感影像为数据源,同时结合GIS手段,选取多指标,综合分析北京生态风险等级分布,并对各指标因素进行打分,最终得到北京地区生态风险评估图。结果表明:在人口密集区域,由于其与人类活动息息相关,有较高的生态风险等级;总体上看,北京山区北部的生态风险等级要高于南部,西部要高于东部;具有相同生态风险等级的各区域主要风险源不同,但总体上相近地区的主要风险源相同。基于早期的生态风险评估理论,将水土流失问题作为研究重点,克服传统的单因子评价、综合指数评价和生态风险指数评价的不足,构建一种新的生态风险评估方法,为生态风险评估提供参考依据。

[ Background] Ecological risk assessment has been studied by many countries and research scholars. The conventional index of evaluation system is difficult to obtain, which makes ecological risk assessment in some underdeveloped regions infeasible. The constant transformation of land type and structure, the substantial reduction of agricultural land; meanwhile, industrial and mining production emissions of chemicals has caused the environmental degradation in mountainous areas, population exploslon, habitat loss, loss of biodiversity, etc. China＇s current risk assessment borrows from other types of ecological risk assessment system, which does not have an appropriate assessment system, and data collections some evaluation indicators of are too complicated. Thevefore, how to evaluate ecological risk assessment in practice？ How to conduct effective ecological risk assessment and benefit of the production and construction？ [ Methods] Based on the research of ecological risk assessment, we analyzed the system according to sources of risk, risk receptors, exposure and hazard. Taking Beijing as the data source for remote sensing images, combined with GIS tools to analyze Beijing ecological risk level of distribution, selected multiple indicators were analyzed. We also studied key indexes in Beijing ecological risk assessment system, and endowed weights for each indexes, and finally obtained Beijing ecological risk assessment maps. [ Results ] 1 ） In densely populated areas, there have a higher ecological risk levels （Moderate risk and High risk） because of its closely related to human activities. 2） Overall,ecological risk level （ Mild risk） of northern and western mountain area is higher than those in the southern and the eastern. 3） When two regions have the same ecological risk level, the major sources of risk may be different due to regional characteristics, however, neighborhoods trend to have the same major sources of risk. 4） By building and screening the index and ecological risk assessment system, a reasonable transformation of these indicators for ecological risk assessment system has been fitted in this system. At the same time, combined with the current research progress and soil and water loss investigation, it can be used in other parts of ecological risk assessment model for other areas. [ Conclusions] Based on an earlier ecological risk assessment theory, the new ecological risk assessment methods can overcome the shortcomings of traditional single-factor evaluation, comprehensive index evaluation, and conducive to ecological risk assessment for other regions.