# Correlation between Soil Moisture Change and Geological Disasters in E'bian Area (Sichuan, China)
## 2 Materials and Methods
### Study Area
The more diverse the terrain in the study area, and in combination with the terrain and landform features, adjusting the spatial autocorrelation degree of different areas and selecting a smaller calculation window can truly reflect the geological features of the area. By sliding the window on the geographic data, spatial changes and patterns can be detected, which are helpful to understand the spatial distribution and change trend in surface features so that surface features and geographical phenomena can be better understood. \[\text{Mean}(\text{i},\text{j})=\frac{1}{\text{n}^{2}}\sum_{\text{p}=1}^{\text {n}}\sum_{\text{q}=1}^{\text{n}}\text{Z}\Big{(}\text{i}-\text{p}+\frac{\text {n}}{2},\text{j}-\text{q}+\frac{\text{n}}{2}\Big{)} \tag{1}\]  
where Z is the matrix of elevation values (window size n \(\times\) n), Mean(i,j) is the mean of the window at (i,j), and n\({}^{2}\) is the total number of elements of the window. NDVI, TVDI, and LST are currently widely used in the field of environmental research. Among them, the Temperature Vegetation Dryness Index (TVDI) has a certain limitation, that is, it is not applicable to areas with high vegetation coverage (FVC). Vegetation can affect surface temperature by changing the physical characteristics of the surface. In addition, vegetation can induce geological disasters by affecting the stability and erosion resistance of the soil. On the other hand, vegetation can reduce the risk of geological disasters by enhancing the structural stability of the soil through its root system and reducing soil erosion. Surface temperature can affect the development of geological disasters by affecting soil moisture and the evaporation rate. For example, high surface temperatures can accelerate the evaporation of soil moisture, cause soil drying, and increase the risk of geological disasters. Generally speaking, the higher the vegetation coverage, the lower the surface temperature. Therefore, this article uses remote sensing technology as a research method; combines the vegetation coverage, surface temperature, and Temperature Vegetation Dryness Index; constructs a virtual triangle model formed by surface temperature and normalized vegetation index (NDVI), where TVDI is used as an indicator of drought changes and reflects the relationship and change law between NDVI and surface temperature (LST); studies the development law of geological disasters in the research area from an environmental perspective; and opens up a new research direction. In this article, the spectral feature space of normalized vegetation index (NDVI) (Equation (2)) and surface temperature (LST) was constructed by using Landsat high-spatial resolution images, and the Temperature Vegetation Drought Index (TVDI) of the study area was extracted to compare the correlation between vegetation coverage and soil moisture change from a mathematical perspective. Combined with the classification of soil moisture critical values [42; 43], the promoting and hindering effects of soil moisture on geological disasters were analyzed, which provided a basis for the restoration of ecological environment in the later period.