Abstract
Since the beginning of the 2000s, Abidjan, the Ivorian economic capital, has been facing difficulties in providing drinking water to its inhabitants. This situation has led scientific research to look into potential sources of drinking water that can meet the needs of a rapidly growing urban population in both quantitative and qualitative terms.The ‘‘Aghien lagoon’’ project is part of this resarch problem. This lagoon is fed by the surface waters of the Aghien watershed (351 km2) and the Mé watershed (4300 km2). The use of this lagoon as a potential source of drinking water requires a diagnostic and prospective study of land use in the watersheds of Aghien and Mé. Our study analyzes, on the one hand, land-use changes between 1987 and 2015. On the other hand, based on these observed changes, it simulates land use in 2030. The methodology of the study is based on land use mappingfrom satellite images of high spatial resolution (Landsat Thematic Mapper of December 1987 and Sentinel 2 of December 2015). The 2030 simulation of land use was based on a prediction model using a Markov chain. The results of the study show two watersheds with very different uses. The watershed of the Mé is marked by the increase of cultivated agricultural surfaces, while the Aghien watershed is characterized by a decrease of these agricultural spaces of 10%, in favor of the urban extension of Anyama, Abobo and Bingerville cities. In the Méwatershed, extensive agriculture led to deforestation of 18% between 1987 and 2015 (from 159,000 ha to77,000 ha of dense moist forest). The analysis of anthropogenic pressures indicates that the food and urban land needs will intensify until 2030 the land use dynamics already initiated.