Risk assessment of disaster chain in multi-seam mining beneath gully topography

Mining-induced geological disasters in gully landforms exhibit distinct characteristics of disaster transformation, with various types of disasters often displaying temporal and spatial chain reactions. The research on the risk assessment of disaster chains in multi-seam mining beneath gully topography is still in its nascent stage. The research area, characterized by its multi-seam mining and gully landforms, has been confronting significant natural and anthropogenic environmental issues within the region. Mining subsidence and mining landslides represent critical disasters in this area. Consequently, this study quantified the degree of disturbance caused by multi-seam mining, considering it as a factor influencing subsidence, which was incorporated into the classification analysis of mining subsidence intensity alongside geological factors and distance from geological structures. A random forest (RF) model was employed to generate a subsidence hazard mapping, and the outcomes of subsidence hazard mapping were utilized as one of the triggering factor parameters for landslide susceptibility mapping (LSM). Simultaneously, a rainfall-runoff layer was introduced to convert the non-uniformity of rainfall, which is challenging to consider in small research areas, into the non-uniformity of runoff, which is used in the LSM together with elevation, slope, aspect, and landcover. The resultant map corresponded with the field investigation results, validating its added value. Moreover, the formation mechanism and risk analysis of the multi-disaster chain, specifically the “subsidence-landslide-barrier lake” in the research area were investigated. The findings indicate that the gully terrain provides a natural advantage for the occurrence of disasters, and rainfall and multi-seam mining exacerbate the vulnerability of the regional geological environment, fostering a complex and protracted disaster chain within the gully area. Lastly, a comprehensive assessment of multi-disaster risks was conducted, and corresponding mitigation measures and recommendations were proposed for various risk stages.