*4.2. Distribution of Land Cover*

Classifications made on the basis of the different land-cover classes that were identified made it possible to produce a land-cover map of the entire study area for each of the composite images, i.e., 1985, 1990, 2000, 2005, 2015, and 2020. The results of classifications without vegetation indices for the six targeted years were mapped (Figure 3). Regarding the results of the classifications with vegetation indices, predictions of the water body class and those of the built-up and bare land (building + soil) class were overestimated. With regard to the visual interpretation of the image composites before classification and the land cover contained in the field data, it was noted that these results of classifications with vegetation indices were not improved compared to the others and reflected the field realities less. Therefore, we decided to continue the other analyses with only those classifications without vegetation indices, considering that further, more specific studies involving the combination of other data could better elucidate the real impacts of these indices on the image classifications.

**Figure 3.** Land cover maps of the classifications of the six composites without vegetation indices.

Since the study area is located in tropical regions where the availability of optical data is very often limited by cloud cover [77], we included this latter as a land-cover class (but which is not presented in the following analyses). Apart from clouds, results of the classifications indicate that in 1985, there were four main land-cover classes, viz., dense dry

forest (10,722.53 km2), open forest (17,547.75 km2), crops and fallow land (11,940.55 km2), and savannah (14,533.13 km2), which represented 18.92%, 30.97%, 21.07%, and 25.65%, respectively, of the nation's land surface. The lowest land-cover percentages were water bodies (0.09%) and built-up and bare soil (0.50%) classes. A quantitative evaluation of these land-cover changes and conversions between target years, as well as those between starting and ending years, was provided (Table 6).


**Table 6.** Land-cover change and conversions between the target years 1985-2020.

Note: LULC = Land Use and Land Cover; Conv. = Conversions; Sup. = Area (Superficie); Bldg. + soil = buildings and bare land.

The area of each land cover has changed slightly for some and greatly for others in different directions in all the target years during the period considered by this study (Figure 4).

**Figure 4.** LULC changes as percentages of the study area.
