Suitability evaluation and reclamation objectives for advanced land reclamation in coal mining pre-subsidence area

The suitability evaluation of land reclamation in coal mining subsidence area is helpful to carry out land reclamation work scientifically in mining areas. In this manuscript, Zhaogu 1st Mine was used as an example, and ten indicators were selected from four aspects of topography, location conditions, soil conditions and human conditions to construct the land reclamation suitability evaluation system, and constructing the spatial dataset of evaluation indicators from the spatial level based on ArcGIS grid analysis function. At the same time, the triangular fuzzy analytic hierarchy process (TF-AHP) was used to empower the evaluation indicators from the suitability of cultivated land, garden and woodland. This method takes into account the subjective ambiguity of the evaluator, thereby improving the accuracy of weight distribution. Then, the weighted superposition of the spatial data of each index was realized by grey correlation analysis, and the suitability distribution of the three reclamation directions was obtained by the natural breakpoint module in ArcGIS. On this basis, we introduced an improved comprehensive extreme evaluation method for suitability analysis, which combined the order of land code of the second national land survey, suitability level of cultivated land, garden and woodland to obtain a five or six evaluation integrated value (MLS). The results can reflect the status of land use of the evaluation unit, and also reflect the suitability level of the unit for different reclamation directions. The research area was divided into 102 evaluation units by using MLS as the fusion field. And according to the principle of “adapting to local conditions, prioritizing cultivated land and reclaiming into the most suitable land type”, the direction of reclamation of each reclamation unit was determined. Finally, the evaluation of the suitability of reclamation in coal mining subsidence area was realized, and the suitability level of each reclamation direction was delimited. The results showed that there are differences in the suitability of different reclamation directions in the study area, mainly manifested as woodland > garden > cultivated land. Based on GIS, the study area was divided into 102 evaluation units with consistent or similar attributes. With comprehensively considering the results of suitability evaluation and natural and economic conditions and infrastructure conditions, the study area was finally divided into four reclamation sub-areas, and 10 sub-division levels: the suitable area of cultivated land was 1 296.09 hm2, accounting for 62.95% of the total area, mainly distributed in the light and moderate damage zone of the central and western subsidence area. The suitable area of the garden was 16.29 hm2, accounting for 0.79%, scattered in the light and moderate damage zone. The suitable area of forest land was 689.49 hm2, accounting for 33.48% of the total area, mainly distributed in the middle-eastern subsidence which had a large terrain relief. The unsuitable area was 57.15 hm2, accounting for 2.78% of the total area, mainly concentrated in the northern edge area of the central severe damage area. The evaluation method of this manuscript took into account the difference of the contribution degree of the evaluation indicators of different reclamation directions and the subjective ambiguity of the evaluator. The use of GIS reduced human interference and made the evaluation unit division more objective. And which has better application than the traditional evaluation method and makes the evaluation results more scientific and reliable.