## 2 Study the Regional Profile and Data Sources
### Data Sources
#### 2.2.2 Landslide Influencing Factors Data  
Landslide influencing factors reflect the complex environmental characteristics that contribute to landslide development from different perspectives. There are hundreds of factors that can affect landslides, which can be divided into categories such as geomorphological, geological, human activity, and environmental conditions. Slope and elevation can provide potential energy for the occurrence of landslides [24; 25]. Considering the historical cases, areas with high elevations and steep slopes in the study area are more prone to landslides. Aspect affects the degree of precipitation and solar radiation received by the region [26], which in turn influences water movement and soil properties, thereby affecting landslide occurrence. Lithology and rock types have a significant impact on the type of slope soil, slope structure, and soil shear strength [27]. Distance-based influencing factors are calculated using Euclidean distance. The distance to faults affects the mechanical structure of the landslide body, as the discontinuity of the rock and soil mass cut by various structural surfaces can create conditions for downsliding. The distance to rivers reflects the effects of surface runoff erosion and soil erosion on landslide evolution [28]. Land use and road distance reflect human utilization and modification of natural conditions, and human activities, such as road and railway construction, irrigation, and residential development, can increase the frequency and possibility of landslide disasters [29]. The Normalized Difference Vegetation Index (NDVI) is used to evaluate the growth status of surface vegetation. When the NDVI value is relatively small, it indicates poor vegetation growth and poor soil stability, which may have a higher landslide risk [30]. Rainfall is an important triggering factor for landslides, as abundant precipitation can increase the water content of the surface and subsurface, change the physical properties of the soil, reduce the soil's shear strength, and increase soil permeability, thereby exacerbating the occurrence of landslides [31].  
The above landslide influencing factors all contribute to landslides in Lanzhou to varying degrees. This paper refers to common landslide influencing factors and analyzes the relationship between the geological environment, development, and distribution characteristics of landslide disasters in the study area of Lanzhou City. A total of 10 influencing factors were selected, including distance to roads, elevation, distance to faults, distance to rivers, average annual rainfall, slope, NDVI, aspect, lithology, and land use.  
The construction of landslide influencing factors is shown in Figure 2. The detailed data sources and resolutions of the landslide influencing factors are shown in Table 2. Considering the size of local landslides and the available data, the spatial resolutions of 10 m, 30 m, and 50 m were selected. If the selected resolution is too high, it willintroduce noise and increase data redundancy. Conversely, a low resolution will simplify the data, leading to a decrease in landslide recognition accuracy. This study uses collinearity analysis and the random forest algorithm to determine the final landslide influencing factors for training [32].  
Figure 2: Influencing factors for landslides. (**a**) Influencing factors of elevation. (**b**) Influencing factors of slope. (**c**) Influencing factors of aspect. (**d**) Influencing factors of lithology. (**e**) Influencing factors of distance to faults. (**f**) Influencing factors of distance to rivers. (**g**) Influencing factors of land use. (**h**) Influencing factors of distance to roads. (**i**) Influencing factors of NDVI. (**j**) Influencing factors of average annual rainfall.