Evaluation of the degree of land destruction in mining areas using improved fuzzy comprehensive evaluation method

Evaluation of the degree of land destruction in coal mining areas is critical for suitable land reclamation measures. A number of studies have evaluated the degree of land destruction in coal mining areas in China and around the world. Currently, the common evaluation methods used include the extreme conditions method, fuzzy comprehensive evaluation method, geographic information system (GIS)-based statistical evaluation method, and the index method. While these methods can reflect the degree of land destruction in coal mining areas, there still is difference in evaluation results due to no uniform criteria for determining the index weight. For the same evaluation method, evaluation results are different when different methods are used to determine index weight. Therefore, the precise determination of index weight has remained the core issue of evaluation methods, which directly affects the accuracy of evaluation results. The G1 method proposed by Yajun Guo is an empowerment method that deals with consistency issue of analytic hierarchy process (AHP) and other subjective methods. The characteristics of G1 include a reflection of the importance of indicators by subjective sorting without limiting the number of indicators and dispense with checking consistency. However, the G1 method has no clear description for sorting indicators and is hardly consistent in sorting expert comments. In this study, the fuzzy opinion centralized decision was applied to the G1 method to sort expert comments. This comprehensive treatment of the method gave a group of more reasonable indicator sorting. The method was used to determine the weight of each index and then to establish an improved fuzzy comprehensive evaluation method. The final method successfully resolved excessive subjectivity common in the determination of index weight. The improved fuzzy comprehensive evaluation method was then used to evaluate the degree of land destruction in Fukangyuan Coal Mining area in Shanxi Province. According to the types of land damage, the study area was divided into two categories — subsided land and occupied land, which had a total of 5 evaluation units. An evaluation index system was then established and the weights determined using the improved G1 method. The extents of damage of the 5 evaluation units were eventually evaluated. The results showed that 2 of the 5 land units had moderate destruction, 2 had mild destruction and then 1 had severe destruction. The results obtained with the improved evaluation model were consistent with those obtained with other methods. When combined with field research, the improved method had a higher reliability. Compared with the classical fuzzy comprehensive evaluation method, the improved method emphasized scientific weight determination to overcome the shortcomings of the classical method with which the weight distribution was unreasonable for larger numbers of indicators. This meant that the improved fuzzy comprehensive evaluation method was more suitable for application in evaluating the degree of land disruption in coal mining areas. The method was suitable for determining the state of destroyed lands, establishing land reclamation measures, restoring and reconstructing ecological environments, and consolidating land protection programs.