## 3 Results
### Characterization of HZ Polygon
#### 3.4.2 Clusters Analysis  
The boxplots illustrating the VH/VV ratio (Figure 15) for different clusters reveal a consistent temporal pattern across all clusters. Particularly, there is a distinct rise in the discrepancy between the two bands during late spring and summer, followed by a gradual increase in the index during autumn and winter. Analyzing individual clusters, Cluster 1 consistently exhibits a higher prevalence of the VH band over VV compared to Clusters 2 and 3, both of which show a similar trend and comparable medians.  
Figure 12: Explained variance of the principal components (PC) that accounts for at least 90% of the total variance.  
Figure 13: Curve of Inertia (SSE) values for K-means clustering with the elbow point highlighted.  
Concerning the NDVI index (Figure 16), distinct temporal patterns are observed. Cluster 3 consistently maintains uniform median values throughout the year, experiencing a rapid decline in the index during November and December. Cluster 3 demonstrates higher index values during winter compared to Clusters 1 and 2 but significantly lower values during the summer period. In contrast, Clusters 1 and 2 follow a more analogous temporal trajectory, with values peaking during the summer and experiencing a sharp decline in late autumn. It is noteworthy that Cluster 2 maintains higher median values compared to Cluster 1, except during the summer months, when Cluster 1 exhibits a substantially higher value.  
Figure 14: K-means classification of the HZ cover.  
Figure 15: Panel of boxplots depicting the distribution of VH/VV ratio values in dB across various months for different clusters, obtained from the sampling points.  
Regarding the NDMI index (Figure 17), all clusters show a similar temporal trend characterized by two distinct peaks during spring and late autumn, with a subsequent decrease during the early months of the year and in the summer. Concerning the individual clusters, Cluster 3 displays higher values compared to Clusters 1 and 2 during the initial and final months of the year, while being markedly lower during the summer period. Clusters 1 and 2 demonstrate a pronounced peak in spring and early summer, with the median value of Cluster 1 being consistently higher than Cluster 2 during this period, while the latter exhibits higher values during the winter months.  
From the analysis of elevation data at random sampling points within the different clusters (Figure 18), higher values of Cluster 1 can be observed compared to Clusters 2 and 3, which are more similar. However, when examining the overall data distribution using boxplots, considerable variability is evident in Cluster 3.  
Figure 16: Panel of boxplots depicting the distribution of NDVI index across various months for different clusters, obtained from the sampling points.  
Figure 17: Panel of boxplots depicting the distribution of NDMI index across various months for different clusters, obtained from the sampling points.  
The non-parametric Kruskal-Wallis test was employed to examine statistically significant differences in the elevation of sampling points, as the data deviated from normality assumptions. The consistently low p-values, approaching zero, provide robust evidence for rejecting the null hypothesis of equal altitude distributions (Table 11).