## 3 Research Method and Process
### Calculation and Data Processing Method
#### 3.2.2 Calculation of Soil Erosion Modulus  
(1) Under the annual erosion rainfall scale  
The Chinese General Soil Loss Equation (CSLE) proposed by [PERSON] et al. [36; 37] is adopted. The equation is based on the USLE (Universal Soil Loss Equation) and RUSLE (Revised Universal Soil Loss Equation) models in the United States and is combined with the characteristics of soil erosion and soil slope characteristics in China. It is suitable for predicting and calculating soil erosion intensity in China. Since the calculation results of the CSLE model are more in line with the actual situation in China, it has been adopted by the 'Soil Erosion Classification and Grading Standard' (SL190-2007) and has become a recommended method for calculating the soil water erosion modulus at the annual erosion rainfall scale. Therefore, many scholars at home and abroad [38; 39] have carried out research on soil erosion in different types of regions based on this equation, including coal mining areas in the northwest. For example, [PERSON] et al. [40] studied the dynamic changes in soil erosion in the Shendong mining area using this model. In view of this, the CSLE equation is more suitable for the study of soil erosion characteristics and the change rules in the loess coal mining subsidence area in northern Shaanxi. In the CSLE model formula, the rainfall erosivity factor was based on that of [PERSON] et al. [41], and the R in northern Shaanxi was 1471.4 MJ\(\cdot\)mm\(\cdot\)hm\(\cdot^{-2}\)h\({}^{-1}\)a\({}^{-1}\). The soil erodibility factor is combined with the calculation method proposed by [PERSON] et al. [42] and the study of [PERSON] et al. [43] on the soil erodibility of the loess slope in northern Shaanxi. The soil \begin{table}
\begin{tabular}{c c c c c c c} \hline
**Lithologic** & **Elastic** & **Tensile** & **Volumetric** & **The Angle of** & **Poisson** & **Cohesive** \\
**Characters** & **Modulus/(MPa)** & **Strength/(MPa)** & **Weight/(KN\(\cdot\)m\({}^{-3}\))** & **Internal Friction/(\({}^{\circ}\))** & **Ratio** & **Fores/(MPa)** \\ \hline Loess layer & 107.0 & 0.20 & 18.60 & 37.2 & 0.30 & 0.60 \\ Fine-grained & & & & & & \\ sandstone & 3270 & 3.79 & 24.11 & 40.0 & 0.28 & 0.15 \\ Mudstone & 3450 & 2.20 & 24.30 & 37.0 & 0.36 & 1.16 \\ Medium-grained & & & & & & \\ sandstone & & & & & & \\ Silstone & 4430 & 1.31 & 24.50 & 40.0 & 0.44 & 3.20 \\ Coal seam & 2570 & 0.24 & 13.60 & 38.5 & 0.36 & 0.61 \\ Base plate & 4720 & 1.86 & 23.81 & 37.7 & 0.35 & 3.60 \\ \hline \end{tabular}
\end{table} 
Table 2: Physical and mechanical parameters of each rock layer. erodibility K value is 0.306 t\(\cdot\)hm\({}^{2}\cdot\)h\(\cdot\)(MJ\(\cdot\)hm\({}^{2}\cdot\)mm)\({}^{-1}\); the slope length and slope factor (L, S) were calculated by the formula proposed by [PERSON] et al. (2014) and [PERSON] et al. (2015, 2016). The vegetation coverage and biological measures factor B was obtained by the vegetation coverage equation proposed by [PERSON] et al. (2017). The factor E of soil and water conservation engineering measures was selected as 0.9, and the factor T of tillage measures was set as 1. (2) Typical erosion rainfall scale  
The empirical formula of [PERSON] et al. (2016) is based on the long-term rainfall erosion characteristics, slope morphology, and soil erosion dynamics in the Loess Plateau. After many field verifications, it is widely used in soil erosion analysis in the Loess Plateau and other erosion sensitive areas. The formula can effectively predict soil loss under different rainfall conditions by quantifying the interaction between rainfall, slope, slope length, and soil erosion. In this paper, three typical rainfall conditions (16.6 mm, 26.9 mm, 39.7 mm) in the empirical formula of [PERSON] et al. were selected, and the soil erosion modulus was calculated by combining slope and slope length, as shown in Table 3. In the analysis of the model, It is understood that the main erosive rainfall in the Loess Plateau of northern Shaanxi is concentrated within the range of 15 to 45 mm.