*4.1. Analysis of the Land-Use Evolution*

#### 4.1.1. Cropland and Grassland Evolution

Agricultural land is becoming increasingly scarce and threatened by several factors. This situation can be fast/slow and differs from one country to another. Therefore, the transition of agricultural land is relatively fast in developed countries due to industrialization but is slow in underdeveloped countries. Tables 2 and 3 shed light on the rate of evolution in agricultural land area, and urbanization has been increased in the last few decades. On the other hand, grassland has decreased.

**Table 2.** The statistics of the land-use area in years 2009, 2012, 2015 and 2018 (km2).


**Table 3.** Dynamic land-use evolution in the period of 2009–2012, 2012–2015 and 2015–2018 (%).


(−) Decrease in area; (+) increase in area.

The research revealed that an increase in cropland (Figure 2), at the beginning of the study period, which coincides with the year 2009, the cropland represented around 14,569.53 km2. On the other hand, at the end of the study in 2018, the cropland is around 16,687.16 km2. Therefore, a difference of 2117.63 km2 was noted, including an increase of 14.53%. The dynamic attitude of cropland amounts to 1.45. This dynamic seems to be important. This means a potential doubling of the cultivated areas around 2028.

On the other hand, our analysis shows a decrease in grassland. The grassland represented respectively 18,656.27 km<sup>2</sup> in 2009 and 16,566.23 km<sup>2</sup> in 2018, showing a decrease of about −2090.04 km2 (−11.20%). Therefore, the cropland increases as the grasslands decrease.

**Figure 2.** (**a**–**d**) show land use evolution patterns in years of 2009, 2012, 2015, and 2018 in the study area.

As for the results between periods, the cropland also shows fluctuations. Thus, Table 3 reflects an evolution of 6.67% over the period 2009–2012. This result has decreased to 2.40% between 2012 to 2015 with a deviation of 4.27%. Compared to the second period, we have observed in the third period an increase of 4.86%. Therefore, if we compare the first period to the last period, the results reflect that the cropland has not increased significantly. In summary, the cropland has slightly increased by 1.81% between the first and last periods (Table 3). This situation remains the same for the grassland. Respectively, the results are decreasing by −5.10%, −2.31%, and −4.22% and the difference noted between the first and third periods is about 0.88%. In summary, the study highlights important knowledge that an expansion of cropland during the study period (Figure 2). These results are confirmed by the data of the World Bank site (2020). Indeed, they show that the permanent cropland represented 0.30% in 2009 and 0.35% in 2016, increasing 0.05% in Senegal.
