Research on Evaluation Methods for Ecological Destruction and Pollution Status of Historical Abandoned Mines—Taking the Gansu Section of the Yellow River Basin as an Example
To evaluate the current state of ecological destruction and pollution at historical abandoned mines in the Gansu section of the Yellow River Basin, and to facilitate comprehensive ecological assessments and remediation strategies, this study introduces a robust evaluation methodology for the mining ecological environment, employing the analytic hierarchy process(AHP). This methodology meticulously accounts for intricate geological conditions, land degradation, pollution levels, and other vital ecological, factors pertinent to mining sites. It is specifically tailored to ensure that the evaluation outcomes align with the multifaceted requirements of natural resource management, forestry and grassland management, and ecological environment authorities. Initially, twelve evaluation indicators were identified across three dimensions: ecological damage, vegetation destruction, and pollution status. A scientifically rigorous indicator system was developed based on empirical field survey data of the mining ecological environment within the study area. Subsequently, judgment matrices were formulated using the analytic hierarchy process, integrating insights from regional mining ecological environment surveys. Scripts were developed using MATLAB software to compute the eigenvectors, eigenvalues, and consistency indices of the matrices. The execution of these scripts resulted in the determination of weight coefficients for each evaluation indicator. Subsequently, the evaluation results were validated through cross-verification with actual survey data and preliminary assessment grades from historical abandoned mining areas within the Yellow River Basin in Gansu Province. This process established definitive threshold values for grading the overall assessment levels. The method facilitates a comprehensive evaluation and grading of mining-related ecological environment issues, thereby providing theoretical support for the formulation of differentiated remediation strategies. The feasibility of the method was demonstrated using Lanzhou as a representative case study, where the evaluation results exhibited a high degree of concordance with on-site investigations. The findings indicate that among the 34 townships affected by mining activities, 10 were classified as severely impacted, 13 as moderately impacted, and 11 as lightly impacted, based on the degree of influence. Consequently, recommendations for ecological restoration strategies that emphasizegraded control and optimized sequencing have been proposed. This approach offers a scientific framework for the implementation of targeted ecological management interventions in mining areas situated within ecologically fragile zones.
①构建判断矩阵。判断矩阵的建立是从层次分析结构的第二层开始,对上一层的某一因素从上到下依次计算各因素在某一层次上的权重,并通过两两对比对矿山生态破坏和污染状况的影响的相对重要性(标度法)来构造判断矩阵(表2)。层次分析法由美国运筹学家托马斯·萨蒂于20世纪70年代提出,通过构建判断矩阵量化因素间的相对重要性,利用线性代数知识,精确地求出判断矩阵的最大特征根所对应的特征向量,目的是对各测评要素的重要程度进行排序,归一化后的特征向量即为评价指标的权重。以构造目标层—准则层判断矩阵为例,其判断矩阵(记为 A )见表3。
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