Susceptibility assessment of soil-water hazard chain on a small catchment in gully region of Loess Plateau: Implications for artificially-induced mountaintop removal filling valley and geoheritage

Soil-water hazards are the most common hazards in Loess Plateau, China, and they can impart devastating effects on living environments of human beings, land planning, and geoheritage sites. A typical study area was selected to elucidate the relationship between soil-water hazards chain susceptibility and human activities, geoheritage sites. Landslide and gully erosion susceptibility was obtained by using gradient boosting and support vector machines, and then, hazard matrix was carried out to couple landslide and gully erosion susceptibility. Ultimately, the high susceptibility classes of landslides and gully erosion was selected as the material source of soil -water hazards chain. Meanwhile, Flow-R software was applied to acquire soil-water hazards chain susceptibility. Thereafter, different magnification times of soil-water hazards chain was quantified under different scenarios. Fourteen conditioning factors were considered in different susceptibility mapping after a collinearity test. The medium-high susceptibility of landslide, gully erosion, coupling soil-water hazards, soil-water hazards chain accounted for 41.40 %, 46.96 %, 49.11 %, and 51.14 % of the entire area, respectively. The proportion of magnification times were a trend of decreasing from first scenarios to third scenarios when the soil-water hazards magnification times was <5, however, there was a trend of increasing that of different scenarios when the magnification times was >5. Moreover, a series of geomorphological factors and human activities factors were highly important for the occurrence of geohazards, especially in artificially-induced mountaintop removal filling valley obviously amplified the harm of soil-water hazards. In addition, many geoheritage sites were distributed in medium-high susceptibility areas for different soil-water hazards, and their proportion exceeded 40 %. This study provides a novel and useful paradigm for the relationship between human activities and soil-water hazards can attain an optimal state, and a harmonious balance can be established between human beings and nature.