## 4 Results of the Experiment
### Analysis of Spatial Variability in Drought  
#### 4.3.1 Monthly-by-Month Drought Changes in Vegetation in Laibin City  
Based on the findings presented in the preceding sections, the research obtained monthly-by-month drought classification maps for Laibin City in the study region for the years 2021, 2022, and 2023. The analysis included calculating the proportion of area occupied \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Time** & **RSM** & **RVI** & **NDWI** & **TVDI** & **VTCI** \\ \hline
2022.3 & 0–10 cm & 0.617 *** & 0.667 *** & \(-\)0.790 *** & 0.724 *** \\
2022.4 & 0–10 cm & 0.776 *** & 0.587 ** & \(-\)0.820 *** & 0.804 *** \\
2023.1 & 0–10 cm & 0.665 *** & 0.633 *** & \(-\)0.774 *** & 0.753 ** \\
2022.3 & 0–20 cm & 0.596 *** & 0.653 *** & \(-\)0.783 *** & 0.708 ** \\
2022.4 & 0–20 cm & 0.741 *** & 0.583 ** & \(-\)0.795 *** & 0.792 ** \\
2023.1 & 0–20 cm & 0.493 ** & 0.398 * & \(-\)0.525 ** & 0.494 * \\ \hline \hline \end{tabular}  
***, **, and * passed significant correlation levels of 1%, 5%, and 10%, respectively.  
\end{table} 
Table 4: Pearson correlation analysis results between different drought monitoring indicators and soil relative humidity. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Time** & **RSM** & **RVI** & **NDWI** & **TVDI** & **VTCI** \\ \hline
2022.3 & 0–10 cm & 0.509 *** & 0.474 *** & \(-\)0.649 *** & 0.637 *** \\
2022.4 & 0–10 cm & 0.595 *** & 0.516 *** & \(-\)0.66 *** & 0.634 *** \\
2023.1 & 0–10 cm & 0.606 *** & 0.524 *** & \(-\)0.628 *** & 0.619 *** \\
2022.3 & 0–20 cm & 0.497 *** & 0.462 *** & \(-\)0.641 *** & 0.579 *** \\
2022.4 & 0–20 cm & 0.608 *** & 0.477 *** & \(-\)0.621 *** & 0.621 *** \\
2023.1 & 0–20 cm & 0.551 *** & 0.422 ** & \(-\)0.68 *** & 0.669 *** \\ \hline \hline \end{tabular}  
*** and ** passed significant correlation levels of 1%, 5%, and 10%, respectively.  
\end{table} 
Table 5: [PERSON]’s tau-b correlation analysis results between different drought monitoring indicators and soil relative humidity. by each drought class. The results of the drought monitoring indicated that the spatial characteristics of drought conditions in Laibin City over the past three years exhibited significant variability and regularity. In 2021, severe drought conditions were observed in April, July, August, and September, with the proportion of severely affected areas exceeding 15%. Notably, July recorded the highest proportion of severe drought, covering 57.06% of the total area, indicating that more than half of the vegetation area in Laibin City experienced severe drought conditions. The severely affected areas were predominantly concentrated in the southwestern and east-central regions of the city. Moderate drought was prevalent in April, June, August, September, October, and November, with over 45% of the vegetation area experiencing such conditions. In September and November, more than 70% of the vegetation area was under moderate drought, with a small portion of the east-central area experiencing heavy drought. In March, the majority of vegetated areas exhibited light drought conditions, representing the highest proportion of light drought throughout the year at 60.85% of the total area. Additionally, the west-central and northeastern regions displayed a minor proportion of severe drought. Figure 8 shows the monthly drought level results of Laibin City in 2021. Figure 9 depicts the variation in the percentage of drought-affected area in Laibin City in 2021. In 2022, Laibin City experienced varying levels of drought conditions across different months. In January and February, a large area faced light drought conditions or higher, with moderate drought affecting parts of the vegetation area. The proportion of the area experiencing moderate drought was 10.72% and 32.83%, while the proportion facing light drought was 53.10% and 29.69% during these months, respectively.