## 2 Comprehensive Ground Surface Damage Forecast Method
### Comprehensive Damage Area Division  
When it comes to the rural building and cropland damage and destruction level forecast, we first need to extract the displacement and deformation quantities of the research object, and then compare them with the corresponding damage threshold of each deformation index so as to determine the damage level. There are a large number of buildings, random building locations and other problems during the ground surface building damage forecast in the mining area using traditional methods. As for the cropland damage forecast, there are inaccurate damage level forecasts and other problems in view of the planar cropland distribution and its irregular boundary.  
The aforementioned problems can be resolved in a better way through the damage-overridden area division in the mining area. Regarding the damage-overridden area division  
\begin{table}
\begin{tabular}{c c c c} \hline \multirow{2}{*}{**Damage Level**} & \multicolumn{3}{c}{**Surface Movement Deformation Thresholds**} \\ \cline{2-4}  & **Subsidence (mm)** & **Horizontal Deformation (mm/m)** & **Inclined Deformation (10\({}^{-3}\)/m)** \\ \hline mildly damaged & \(<\)1500 & \(<\)4.0 & \(<\)6.0 \\ moderately damaged & 1500–3000 & 4.0–8.0 & 6.0–12.0 \\ severely destroyed & \(>\)3000 & \(>\)8.0 & \(>\)12.0 \\ \hline \end{tabular}
\end{table}
Table 2: The classification standard for coal-mining-induced cropland damages.  
Figure 4: The characteristics of building damages caused by different deformation indexes: (**a**) Positive horizontal deformation; (**b**) Negative horizontal deformation; (**c**) +k Positive curvature deformation [10\({}^{-3}\)/m]; (**d**) Negative curvature deformation [10\({}^{-3}\)/m]; (**e**) Inclined deformation [10\({}^{-3}\)/m].  
sion by virtue of Arc GIS, we first need to discretize the ground surface into regular raster, and then assign the displacement and deformation at each point on the ground surface triggered by coal mining to each raster using the Kriging method. According to the assessment standards of building and cropland damage severities, the damage severities of each raster caused by different displacement indexes are analyzed so as to divide the damage-overridden range determined by each deformation index in the targeted area. The specific division process is shown in Figure 5.  
The damage levels of buildings and croplands on the ground surface are subject to joint influences from multiple displacement indexes. When it comes to the assessment of the same target in the mining-influenced area, the damage judgment thresholds of each deformation index are different, thus resulting in differences in damage levels from the judgment. Therefore, the ultimate building and cropland damage levels in this point should be assigned with the highest values according to the damage levels judged by each deformation index. Based on this judgment rule, we can obtain a map of damage ranges caused by multiple deformation indexes on the ground surface in the targeted area. We can produce a map of damage ranges caused by the multiple deformation indexes integrated on the ground surface in the targeted area. This can be achieved by superimposing multiple damage range maps produced by single deformation indexes by virtue of GIS (The principle is shown in the Figure 6).  
Through the comparison of the comprehensive damaged area division results with the building and cropland locations on the ground surface, the building and cropland damage forecast in the coal-mining-influenced area can be realized in a quick, accurate and visualized manner. The locations of low damage levels can provide guidance and serve as the sites for building relocation and new buildings.  
Figure 5: Process for the regional delineation of surface damage classes in mining-affected areas.