Abstract
Sustainable management of Ivory Coast’s freshwater reserve at a catchment scale is an essential way in the policies of land use sustainable management. Thus, the implementation of physical conceptual semi-distributed SWAT model required a good knowledge of the watershed and a large number of physic-chemical data available that have been prior adapted to Ivory Coast’s climatic and soil conditions. The whole simulation span was divided into calibration set (1982-1986) and validation set (1987-1990). The SUFI-2 algorithm was used for parameters optimization. The sensitivity analysis focused on 8 parameters related to runoff, soil, evaporation, main channel and groundwater. The performance criteria were based on the P-factor, R-factor and the two objective functions which are Nash-Sutcliffe coefficient and the coefficient of determination. Although Taabo river basin like African basins suffers from a significant lack of data, the objective functions showed the robustness of the model to climate variability. The calibration launched during a wet period gave objective functions higher than 0.7 while validation performed in less humid period gave performance criteria around 0.6. During the simulation period, Taabo river basin daily green water ranged from 0.044 to 50.257 mm/day with a total average of 3,090.9 mm per year. As for blue water, it is ranged from 0.032 to 0.552 mm/day with an annual total average of 29.19 mm.
Highlights
Taabo river basin like African basins suffers from a significant lack of data, the objective functions showed the robustness of the model to climate variability
The freshwater resources of the basin produced by SWAT model are divided into two components: blue water or internal renewable water resource (IRWR) and green water [16]
Since all the sensitive parameters do not have the same impact on the model output variables, the Table 1 summarizes the SWAT model parameters range included in the final calibration/validation of Taabo river basin
Summary
The purpose of this study is to quantify the current state of Ivory Coast freshwater resources. It will allow from a relevant diagnosis of all physic-chemical phenomena, the assessment at the catchment scale of major water resources. An approach of this problem through tools such as hydrological models [2] [3] [4] [5] appears as a decision support tool to consider [6]. The SWAT (Soil and Water Assessment Tool) model, taking into account the spatial heterogeneity of the soil has been tested on the Taabo watershed. The model may contain errors, the evaluation of its performance was possible using the SUFI-2 (Sequential Uncertainty Fitting-Version 2) algorithm of SWAT-CUP software [20] and [21]
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