Like the West African countries, the Sassandra river basin limited at Soubré is facing the challenges of climate change. Seen anthropogenic activities have contributed to modifying the climate in a sustainable way, it is important to have as clear an idea as possible of possible climate changes. The main objective of this study is to characterize the variability of climate parameters in order to sustainably manage its impacts on basin development projects. So, the methodology adopted is divided into 2 steps: the characterization of climate variability and the characterization of climate change to 2030 and 2050 horizon. The results of climate variability showed a decrease in rainfall and an increase in temperatures. In terms of climate change, under scenario RCP4.5, minimum and maximum temperatures are projected to increase by 1.4°C to 1.8°C by 2030 and 2050. At the same horizons and under scenario RCP8.5, there is an average increase of 1.4°C to 2.4°C. In terms of annual rainfall, projections show an upward trend of 1% by 2030 and a downward trend of 1% by 2050 under the RCP4.5 scenario. The scenario RCP8.5 predicts an increase in precipitation with rates greater than 35% at both future horizons.

The white Bandama watershed in its upstream part is strongly anthrophised. Its position in a semi-arid zone gives it a high vulnerability to water erosion. However, water erosion of soils is at the root of many environmental and socio-economic problems. It therefore appears necessary to evaluate soil losses due to water erosion. To do this, the Wischmeier and Smith equation, or Universal Sol Loss Equation: USLE, is therefore a tool of choice for the modeling of the erosive process. This model works with the multiplication of six erosion factors namely the erosivity of the rain, the erodibility of the soil, the inclination and the slope length, the vegetation cover and the anti-erosion practices, in an Geographical Information System. The results obtained are at the scale of the watershed and in spatial unit (pixel of the DTM). Thus, the value of the average losses in 1986 is 42.87 t / ha / year, this value drops to 25.98 t / ha / year in 2001 and stands at 36.53 t / ha / year in 2016. In addition, vegetation cover, erodibility and erosivity of rainfall are the factors that most modulate erosion in this basin.

This study is performed on the Ramsar site of Sassandra Dagbego complex that houses important wetlands including the estuary of Sassandra river and mangrove forests. It has for objective to study the state of conservation of this wetland of international importance that is this site Ramsar. Its implementation was made from the exploitation of satellite images at medium resolution (Landsat TM and OLI) and of investigations on the ground. The processing of images on the implementation indices, colorful compositions and supervised classification was used to map land cover in 1986 and 2014 and to analyze the dynamics of natural habitats between the two dates. The results show a dynamic land use characterized by regression over time, mangroves and forests for the benefit of the cultivated and residential areas.