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 km2, located in the north of the district of Abidjan
(South-East from C?te 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 R2 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
R2 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.
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