Potential Impact of Climate Change on the Sediment Fluxes of a Watershed in West Africa: Cas of the Aghien Lagoon, Côte D’ivoire

The semi-distributed SWAT (Soil and Water Assessment Tools) model was used in this study to model the sediment yield in the watershed of the Aghien lagoon with an area of 365 km 2 , located in the north of the district of Abidjan (South-East from Côte d'Ivoire).A sensitivity and uncertainty analysis, as well as calibration of the SWAT model, was conducted using the Sequential Uncertainty Adjustment Procedure (SUFI-2) which is one of the programs interfaced with SWAT in the SWAT-Cup package (SWAT-Calibration-Uncertainty Programs).Five parameters of the SWAT model were found to be more sensitive to sediment fluxes.These have been modified (calibration) sparingly in order to improve the reproduction of observed sediments data.Two measures were used to assess the uncertainty analysis of the model: P-factor and R-factor.The R 2 and Nash-Sutcliffe (NS) coefficients of determination were used to assess the quality of the calibration.The P-factor obtained is 0.58 and the R-factor is 2.28.The NS and R 2 coefficients in calibration over the period from June 2014 to January 2015 are 0.51 and 0.86 respectively.These values indicate correct consideration of uncertainties by the model and satisfactory calibration of the SWAT model for solid fluxes.Then, the model was used to simulate the sediment fluxes at the horizons 2040 (2035-2056), 2060 (2057-2078) and 2080 (2079-2100) in order to assess the impact of climate change on sediments in the watershed of the Aghien lagoon.The results indicate that sediment fluxes could increase in the future under the RCP 4.5 and RCP 8.5 scenarios.With RCP 4.5, sediment fluxes would increase on average by 14.42%.They could increase by 17.95% on average under RCP 8.5.