# Analysing Land Cover Change in the Valencian Community through Landsat Imagery: From 1984 to 2022
## 3 Results
### Land Cover Temporal Analysis  
After model validation, a temporal analysis of land cover change in the Valencian Community was conducted utilising Landsat 5-9 imagery spanning the period from 1984 to 2022. All classification maps obtained can be referenced in Appendix A. Figure 6 provides a zoomed-in depiction of the city of Valencia, showcasing the classification maps derived from Landsat 5 in 1984 and Landsat 9 in 2022, respectively. Figure 6: Land cover classifications of Valencia region obtained with the Random Forest algorithm for the years 1984 (**top**) and 2022 (**bottom**) using Landsat 5 and Landsat 9 images, respectively. A notable surge in the urbanised surface area (Built-up Areas class) over the designated period is evident (Table 2). Specifically, there has been a substantial increase from 481.96 km\({}^{2}\) to 939.40 km\({}^{2}\), indicating a remarkable 94.9% growth for this particular class. This urban expansion has impacted green and cultivated regions (Dense and Sparse Vegetation classes), resulting in a cumulative reduction equivalent to 1.5% of the total area recorded in 1984, transitioning from 22,525.07 km\({}^{2}\) to 22,179.86 km\({}^{2}\). Solely in the Built-up Areas class, there has been an increase of 457.44 km\({}^{2}\), roughly equivalent to 64,000 football fields, signifying a substantial amount of urban expansion. Conversely, the Water Bodies class showed only a slight increase, while the Other class experienced a significant decline, decreasing by 78.8%. This reduction is also attributed to urban expansion. The RF algorithm was systematically applied at five-year intervals throughout the study period (the resulting land covers can be found in Appendix A). This approach facilitated a comprehensive analysis of temporal changes in land cover classes, aiding in the identification of potential trends. Figure 7 visually illustrates these temporal evolutions, graphically depicting the percentage of area occupied by each class referred to as the total area of the Valencian Community. In the case of the Built-up Areas class, a discernible and consistent growth pattern is evident, increasing from 2.08% in 1985 to 3.91% in 2020 (Tables 3 and 4). Conversely, other classes do not exhibit a clear growth or decline trajectory. Notably, the combined areas of Dense and Sparse Vegetation classes remain relatively constant, indicating an inversely proportional relationship between the two classes. This observation aligns with the annual variations in crop density during the summer season, as well as with the variations in overall vegetation density and intensity. Figure 8 presents a composite graph where the percentages occupied by all classes are collectively represented for each year. In the majority of instances, Dense Vegetation emerges as the predominant class, occupying the highest percentage. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Class** & **Area (km\({}^{2}\))** & \multicolumn{2}{c}{**Percentage Change (\%)**} \\ \hline  & **1984** & **2022** & **1984 \(\rightarrow\) 2022** \\ \hline
**Water bodies** & 93.57 & 103.75 & +10.8 \\
**Built-up Areas** & 481.96 & 939.40 & +94.9 \\
**Dense Vegetation** & 10,879.22 & 13,938.30 & +28.1 \\
**Sparse Vegetation** & 11,645.85 & 8241.56 & \(-\)29.3 \\
**Other** & 154.78 & 32.86 & \(-\)78.8 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Area for each class (in km\({}^{2}\)) obtained using the Random Forest algorithm for the years 1984 and 2022, along with the corresponding percentage change within this timeframe.