# Monitoring of Cropland Non-Agriculturalization Based on Google Earth Engine and Multi-Source Data
## 4 Results
### Spatial and Temporal Analysis of Cropland Occupation  
Verified change patches were overlaid onto the study area map to visualize the spatial distribution of cropland changes across different years (Figure 9). Over the five-year period, Haifeng County exhibited the highest number of change patches, totaling 359, followed by Lufeng City with 278 patches, Chengqu with 121 patches, and Luhe County with only 7 patches. The concentration of changes in Haifeng County aligns with its rapid economic development in recent years, driven by its role within the Shenzhen-Shanwei Special Cooperation Zone in Haifeng County. This finding highlights the link between accelerated economic growth and increasing human-land conflicts.  
Overlaying all the five-year change patches on the DEM of the Shanwei region reveals that changes are mainly concentrated in areas with flat topography (Figure 10), especially in Haifeng County, Lufeng City, and Chengqu. This spatial pattern indicates that areas  
Figure 9: Comparison of cropland extraction results: (**a**) distribution of changes in 2019; (**b**) distribution of changes in 2020; (**c**) distribution of changes in 2021; (**d**) distribution of changes in 2022; (**e**) distribution of changes in 2023.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Year**} & **Number of Preliminary** & **Number of Correct** & \multirow{2}{*}{**Accuracy Ratio (\%)**} \\  & **Change Patches** & & **Change Patches** \\ \hline
2019–2020 & 170 & 120 & 70.58 \\
2020–2021 & 201 & 147 & 70.47 \\
2021–2022 & 201 & 154 & 76.61 \\
2022–2023 & 259 & 198 & 76.44 \\
2023–2024 & 205 & 152 & 74.14 \\ Total/mean & 1036 & 771 & 73.65 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Experimental results of SAR combined with optical image.  
with flat topography and lower elevations are more susceptible to cropland changes, which are often driven by economic development. Therefore, cropland monitoring in Shanwei should prioritize economically active and geographically flat areas.  
The number of cropland change patches in the study area was analyzed temporally on an annual basis. As shown in Figure 11, the analysis reveals that cropland changes in Shanwei City over the past five years followed a pattern of initial increase followed by a decline. Specifically, from 2019 to 2022, the number of change patches increased, with the most rapid growth occurring in 2022. However, in 2023, a noticeable decrease in the number of change patches was observed. This decline is likely attributable to the implementation of strict cropland protection policies and the effectiveness of monitoring technologies, which have played a suppressive role in further land-use changes.  
Overall, the year-on-year increase in the number of cropland occupation patches in Shanwei was suppressed in 2023, but the number remains at a relatively high level. Moreover, there are differences in the trend of patch numbers across different regions. Therefore, it is necessary to strengthen monitoring efforts in economically developed and geographically flat areas, particularly in Haifeng County and Lufeng City.