Research on the reshaping of the near-natural landform of the internal dump for open-pit mine: a case study of Heishan Open-Pit Mine, Xinjiang, China

Open-pit mining is the main development form of China’s mineral resources. In the process of open-pit mining, the traditional “terraced” internal dumps formed by long-term high-intensity human-made disturbances face problems such as large area and fragmented landscape. As an important means of restoration of the mining area, the near-natural landform remodelling has the unique advantage of integrating the landscape outside the mining area. In order to design an open-pit mine dump that is integrated with the surrounding natural landforms, based on the existing mining technology, this research proposes a near-natural landform remodelling of the internal dump by the adjustment of the curved surface under the integration of mining-disposal-refilling. Taking the Xinjiang Heishan open-pit mine as an example, the paper constructs the nearly natural design landform of the inner dump and two experimental control groups, including natural primitive landform and traditional design landform. Finally, the CLiDE evolution model is used to simulate and evaluate the nearly natural design landform’s anti-water erosion effect within 10 years. The results show that: ① In terms of geomorphology design, the near-natural geomorphology reshaping model can show according to the DEM before mining, the DEM of mine roof and the DEM of mine floor during the mining-disposal-refilling integration process to get the available earthwork for the refilling automatically and then obtain the near-natural design results of DEM of the refilling sub-area; ② In terms of earthwork allocation, the average earthwork distance of the nearly natural design landform is 0.49 m/m3 higher than that of the traditional design landform, which is about 0.06% higher than the latter. Their average earthwork distance values are very similar; ③ Visually, the near-natural design landform can be integrated with the surrounding natural landscape. Compared with the traditional “terraced” internal dump, there is no obvious splicing mark between it and the surrounding natural landform; ④ In the process of soil water erosion simulation, the nearly natural design landform can reduce the amount of soil water erosion by about 39.07% compared with the traditional “terraced” landform in 10 years, which can significantly improve the water erosion resistance of the internal dump’s topsoil; ⑤ In terms of soil migration and evolution, the spatial location of the topsoil loss area and accumulation area of the nearly natural design landform has an overlap rate of 57.27% with the original natural landform, which is 2.96% higher than that of the traditional design landform. The surface soil migration characteristics of the near-natural design landform are more similar to the natural landform before mining.