The upstream side of the large watersheds of Benin is undergoing accelerated degradation phenomena, due to human pressure. The objective of this study is to quantify the loss of cultivable soil in the Affon-Donga watershed. The methodological approach adopted was to use the RUSLE model to quantify soil loss. Raster data such as SoilGrids images from ISRIC, elevation images from ASTER GDEM, Landsat OLI images, WoldClim data as well as terrain data were used to prepare the five factors of the model. The results obtained show that the soil loss varies between 0 and 21,598.63 t / ha / year in the Affon-Donga watershed. The loss values ​​of between 10 and 500 t / ha / year occupy 40.54% of the basin. The colossal losses which exceed 500 t / ha / year and go up to 21,598.62 t / ha / year are dispersed over 3.95% of the basin. The average soil loss is 1443.81 t / ha / year and the rate of erosion or the amount of soil moved generally from upstream to downstream is 633,562,753.72 t / year. As the long-term result of such an ecosystem dynamic, cultivable spaces will become scarce while the processes of filling and meandering of downstream rivers will be amplified.

The classified forests of Benin, whether legally protected or traditionally protected, are still under severe pressure. This study object is the evaluation of the degradation of the classified forest of Tchaourou. This Landsat satellite image of 1990, 1999, 2009 and 2019 were used for diachronic analysis and the topo-sequential analysis. The results obtained show that the mosaic of field and fallow in addition to the tree and shrub savannah recorded a growth rate of 21.85 % and 32.05 % respectively for the period from 1990 to 2019. As for the woodland and savannah woodland, it experienced a regression rate of -39.96 %. The gallery forest also fell by -13.94 %. The explanatory factors for this deterioration of the different units of land use are, among others, agriculture, logging, late wildfires, grazing.