Soil erosion by precipitation, rainfall and runoff is a widespread phenomenon in different countries of the world. It becomes disastrous in particular on the slopes because of the torrentiality of the flow, of the strong vulnerability of the grounds (soft rocks, fragile grounds, steep slopes). The present study has for objective: The analysis of the data of concentrations of sediments in suspension are measured at the station of the rivers highlights relations, linking the concentration (or the solid flow) of the sediments in suspension to the liquid flow and to quantify the seasonal, monthly and interannual and intra annual variation of the surface degradation. Annual tonnage estimates of solids loads to the Mé were derived from the power law for all seasons. From this deduction, the annual quantities of sediment transported by the Mé from 2015/2017 is 7.06.106 t/year, or a specific degradation of 1.79.103 t/km2/year. On the other hand, in 2017, the value of this solid input is 3.06.106 t/year. However, the annual solid input is estimated at 7063.03.103 t/year with a specific degradation of 1784.47 t/km2/year at the Mé from 2015 to 2017.

This study proposes to follow the temporal evolution of nitrate contents of groundwater and to map their spatial distribution. For this purpose, physicochemical analyzes and statistical treatments were carried out on 10 boreholes and 12 wells. The nitrate distribution map is obtained using the IDW (Inverse Distance Weitling) interpolation method. Nitrate levels in the Baya watershed range from 0.5 mgL-1 to 196.2 mgL-1. Well water is richer in nitrate than drilling water with an average grade of 28.77 and 13.51 mg.L-1, respectively. Only 12% of nitrate levels are above the WHO guideline (50 mg.L-1) for drinking water. These are the waters of P3 (79.5 mg.L-1), P5 (110.8 mg.L-1) and P8 (56 mg.L-1) and F1 wells (47.1 mg. L-1) F10 (109.6 mg.L-1). In terms of time, unlike the drilling water, the nitrate concentrations of the wells of the rainy season are generally higher (33.96 mg.L-1) than that of the dry period (23.59 mg. L-1). Excessive nitrate levels are observed in the localities of Agnibilekro, Koun-fao, Tanda and the outlet of the main stream of Baya. This increase in nitrate levels is related to the geological nature of the soil and the anthropogenic pressure in the region.