Modelling water flow in a complex watershed in humid a tropical area using SWAT: a case study of Taabo watershed in Ivory Coast

Understanding the water balance of a basin is the most important aspect in water resources development and management programmes. The objective of this study was to implement an agro-hydrological model (SWAT) to model water flow transport within the river network with a perspective to reduce the sedimentation and eutrophication of lakes in Ivory Coast. The daily simulation of SWAT model carried out in the period from 1979 to 1990 has been divided into warm-up (1979-1981), calibration (1982-1986) and validation (1987-1990). For calibrating the model, a preliminary sensitivity and uncertainty analysis in the SUFI-2 algorithm was performed based on 19 hydrologic parameters. The model has given good results of performance and robustness. All statistical parameters (Nash-Sutcliffe coefficient (NS) and the coefficient of determination (R-2)) used to achieve the model performance of above 0.7 for the calibration period and around 0.6 for the validation period. As for the uncertainty criteria (P-factor and R-factor), the observation data are very good in general because more than 80% are bracketed by the 95PPU both for calibration and validation periods. Graphically, the streamflow predictions match well with actual measurements. Water transfers between the soil, surface water, groundwater and atmosphere are largely conditioned by the uneven spatial distribution of pedology, land use and climate.