基于生态风险评价的采煤矿区土地损毁与复垦过程分析

煤炭开采和复垦活动带来强烈的地表变化和生态环境扰动。该文以山西省平朔矿区为例,通过构建评价模型分析采煤矿区的生态风险动态变化。通过采用最小损毁累积模型测算风险源累积损毁影响值,利用遥感影像结合野外实测数据计算生态脆弱度指数,得出矿区2001年和2010年矿区生态风险值,分析不同开采年份中矿区由于采矿和复垦活动带来的生态风险变化。结果表明:随着煤炭产量的增加,2010年土地损毁的累积影响范围比2001年增长了7 095.17 hm2;但是已复垦排土场的损毁累积危害下降明显,并且随着矿区扰动区域的东移,采矿对研究区西部的影响也在减弱。经过10年的土地复垦与生态重建措施,已复垦的排土场生态风险值呈下降趋势,生态系统趋于稳定。在采矿扰动区中,2001年处于中等风险及以下的区域占比为0.02%,到2010年为16.77%。特大型采煤矿区扰动范围较大,但是采后土地复垦有助于降低局部生态风险的影响。通过研究矿区土地损毁情况、复垦过程和复垦后的状态,分析不同区域生态风险的动态变化,可以为矿区的生态环境治理和区域发展规划提供参考,为矿区管理和相关决策提供科学依据。

Process analysis of land destruction and reclamation in coal mining areas using ecological risk assessment

With the development of coal mining and land reclamation, the landforms and environmental conditions in mining areas have been disturbed. It is necessary to take positive initiatives to prevent eco-risks during mining exploitations and construct a key ecological civilization and socio-economic development. This paper used Pingshuo Coal Mine in Shanxi Province as a case study to analyze and build an evaluation model of dynamic ecological risks in coal mining areas. Using 30 m×30 m grid units, the study evaluated, mapped and classified at unit grid scale ecological risks in the mining area. Based on the study, the ecological risk in the mining area varied with land destruction and reclamation processes. A model of the cumulative effect of land destruction was used to assess risk sources. Also remote-sensing images and field measured data were used to calculate the values of ecological vulnerability index in the region. Through index calculations, the ecological risk values for the mining area were determined for 2001 and 2010. Also through the combination of existing remote-sensing techniques with field measurements, the values were reasonably up-scaled for the entire area with a highly visualized evaluation results. Then the effects of potential risks were determined and optimized land use forms and mining technology identified using the dynamic changes in ecological risk. The results showed that with increasing coal production, the cumulative affecting area of land destruction increased by 7 095.17 hm² from 2001 to 2010. However, the cumulative effect decreased obviously for reclaimed dumps. With the continuous eastward open-pit mining, the effect of mining on the west region of the study area weakened. After 10 years of land reclamation and ecological reconstruction, ecological risks in reclaimed dumps declined and the ecosystem seemly stabilized. The medium and low risk area accounted for 0.02% of the disturbed area due to mining in 2001 and up to 16.77% in 2010. This implied that land reclamation reduced the effects of ecological risk in the region. The combined risk value for open-cast and underground mining was unstable, with a value of ecological risk as low as 0.45 or as high as 0.80. The risk of partial uneven subsidence and soil erosion clearly increased in frequency and intensity in the area. The study demonstrated that the analysis of ecological risk could reflect the processes of land destruction and reclamation via mining, changes in ecosystem structure and function, and the spatial heterogeneity in space-time fabric. Hence such analysis was a reference base for planning environment recovery and regional development. As a source of risk for the regional ecosystem, land reclamation in mining areas should focus on increasing the ecological functions of reclaimed areas.