# Correlation between Soil Moisture Change and Geological Disasters in E'bian Area (Sichuan, China)
## 2 Materials and Methods
### Study Area
Industrial pollution, agricultural pollution, and domestic pollution lead to a decline in water quality, soil quality, and air quality, posing threats to human health and the ecological environment. Excessive reclamation and unreasonable construction, etc., lead to land degradation and a decline in ecosystem service functions. These activities have uncovered hidden dangers for the development of geological disasters. The E'bian Yi Autonomous County has an altitude ranging from 1000 to 4000 m, with an average altitude of 1200 m. The terrain is higher in the west and south and lower in the east and north. Influenced by the Longmen Mountain Fault Zone, the current terrain undulations have been formed. The 10 m digital elevation model map, shown in Figure 2, drawn based on satellite image data can clearly reflect the range of elevation changes. Fraction of Vegetation Cover (FVC) refers to the size of the vertical projected area of plants in a specific area, which usually fluctuates according to different factors such as elevation and slope, and is also a key factor affecting soil moisture [19; 20; 21; 22; 23]. The total length of roads along the E'bian area is 1545.2 km, the river system in this area is developed (Figure 3), and the average annual rainfall is as high as 799 mm. In the range of high altitude (1600-4000 m), the distribution of water and heat conditions is not uniform due to the large difference in terrain height, which results in a fluctuation trend in vegetation coverage. In the flat terrain area, the soil moisture content is higher, so there is an increasing trend in vegetation coverage. In the range of elevation below 600 m, the intensification of human activities such as engineering construction and mineral exploitation will lead to a decreasing trend in soil water content (Table 1). The change in ecological environment (temperature, humidity, etc.) in the study area will also have a great impact on vegetation coverage. Therefore, the characteristics of various influencing factors should be combined in the process of geological hazard analysis [24; 25; 26; 27; 28]. Figure 3: Satellite map of the study area. Figure 2: Digital elevation model of the study area. With the rapid development of remote sensing technology, one of its important advantages is that it can provide continuous spatiotemporal data. Higher resolution image data can provide technical means for extracting spatiotemporal information of soil moisture and vegetation coverage in a large range. Soil moisture is an important factor affecting vegetation growth and climate change, and vegetation coverage is an important indicator reflecting the growth status of surface vegetation. Due to the sensitivity of the infrared and microwave bands in remote sensing images to soil moisture and vegetation coverage, through remote sensing technology, we can obtain information such as soil humidity and temperature and analyze the data of these bands to obtain the distribution of soil moisture and vegetation coverage [29; 30; 31; 32]. Based on the acquisition of terrain and landform image data of the study area using remote sensing technology, DEM data are utilized for terrain analysis to extract parameters such as slope and aspect. In this article, slope, slope direction, and surface relief were selected as the constraint factors to study the surface micro-environment and vegetation growth change (Figure 4). Slope can represent the steepness of local surfaces, which is an important factor affecting surface material flow (especially surface water and underground water) and also