Assessment of soil erosion in the Autonomous District of Abidjan, Côte d'Ivoire

Abstract— In a context of global changes and climatic uncertainties, this study poses the problem of the occurrence of water erosion induced by natural constraints and uncontrolled and speculative anthropisation of soils in the Autonomous District of Abidjan. The aim is to propose a decision-making tool that identifies the areas of the Autonomous District of Abidjan (ADA) most prone to soil loss and the risk of water erosion. More specifically, the aim is to evaluate, prioritise and map the levels of susceptibility to the occurrence of this hydroclimatic risk in the ADA. The mapping approach is based on the aggregation of factors such as climatic aggressiveness, soil erodibility, topography, soil cover and anti-erosion practices from the Revised Universal Soil Loss Equation (RUSLE). The exploitation of these data reveals that soil loss in the ADA oscillates between a minimum value of 0 t/ha/year largely observable in the south of the lagoon system to a maximum value of 107.53 t/ha/year which concerns the plateau areas in the north. The average of this series of 0.48 t/ha/year translates into an overall low level of water erosion in the ADA over nearly 95% of the ADA territory. This soil degradation, which impacts human settlements induced by the morphology of the site, is amplified by human activities. In a context of rapid urban expansion linked to a remarkable demographic growth coupled with climatic uncertainties, development policies must better integrate sustainable soil management.