## 2 Study Area and Data Used
### Data Used
A steep slope increases the gravitational force on the soil and rock mass, making it more likely to become unstable and slide. Numerous studies have provided evidence supporting the significance of slope as a critical factor influencing landslide susceptibility. [34]. Slope was reclassified into five categories: <3\({}^{\circ}\), 3-6\({}^{\circ}\), 6-9\({}^{\circ}\), 9-13\({}^{\circ}\) and >13\({}^{\circ}\). The topographic wettability index (TWI) is a measure of the influence of topography on the underlying hydrological processes and it is commonly used to evaluate the susceptibility of slopes to landslides. Higher TWI values indicate greater soil saturation and a higher likelihood of landslides [35]. In the study area, the TWI values ranged from 2.5-30.5, and five categories of TWI were identified: <5, 5-7, 7-12, 12-17 and >17. Surface cutting depth refers to the difference in elevation between the ridge and valley of the surface terrain [36]. Studies have shown that surface cutting depth has a significant impact on landslides' occurrence. A greater surface cutting depth indicates a larger amplitude of relief and more significant differences in terrain elevation, which can increase the potential for landslides due to factors such as soil erosion and weathering [37]. The surface cut depths were divided into five categories: <3.5, 3.5-6, 6-9.5, 9.5-12.5 and >12.5. Plan curvature is a terrain parameter that measures the change in a slope's orientation along a surface. Numerous studies have investigated the relationship between plan curvature and landslides, with many finding a significant correlation between the two [38; 39]. The values of plan curvature were reclassified into five categories: <-0.7, -0.7--0.3, -0.3-0.02, 0.02-0.6 and >0.6. According to existing research, terrain relief is a significant factor affecting landslides. High terrain relief implies a steep slope, and steep slopes have a higher likelihood of experiencing landslides [40]. The terrain relief map was reclassified into five divisions: <7, 7-11.5, 11.5-18.5, 18.5-28 and >28. The distance to roads is also an important factor affecting landslides. Slopes closer to roads are more prone to landslides due to human activities such as road construction and vehicle traffic, which can alter the natural state of slopes and increase their susceptibility to landslides [41]. The distance to the road was reclassified into five categories: <800 m, 800-1600 m, 1600-2400 m, 2400-3200 m and >3200 m.  
The distance to rivers is another important factor affecting landslides. Some studies have shown that slopes near rivers are more prone to landslides because the erosive effects of rivers may cause the slope to become unstable [42]. The distance to rivers was categorized into five groups: <500 m, 500-1000 m, 1000-1500 m, 1500-2000 m and >2000 m.  
SPI, which is a measure of erosion by flowing water, is also considered an important factor affecting slopes' stability. The values of SPI were reclassified into five groups: <-3, -3-1.5, 1.5-2.5, 2.5-4.5 and >4.5. NDVI, serving as an indicator of vegetation cover and health, can contribute to a slope's stability and lower the risk of landslides in regions characterized by high NDVI values [9]. Therefore, NDVI was selected as an indicator for evaluating the susceptibility of slopes to landslides. The NDVI values were reclassified into five categories: <0.15, 0.15-0.23, 0.23-0.28, 0.28-0.36 and >0.36. The terrain roughness index is considered to be an influential variable in landslide susceptibility modeling [43]. Rougher terrain tends to have steeper slopes and less cohesive soils, making the soil more likely to become unstable. The values of terrain roughness index were reclassified into five groups, i.e., <1.01, 1.01-1.03, 1.03-1.11, 1.11-1.16 and >1.16.