Modelling Soil and Water Dynamics in the Black Volta Basin Using the Soil and Water Assessment Tool (SWAT) Model

Abstract

The study focused on the Black Volta Basin (BVB) which is one of the major sub-basins of the Volta River. A high dependency of the population on the basin resources and the lack of sufficient and informed data has led to the under management of its water resources. This research investigated how well the Soil and Water Assessment Tool (SWAT) model can be used to obtain modelled surface runoff flows in the BVB. Spatial data (land-use/land-cover, soil and DEM) together with daily weather data (temperature, precipitation, wind, relative humidity and solar radiation) were used to set-up and run the model. Sequential Uncertainty Fitting II (SUFI2) program was used to evaluate the sensitivity of parameters, and to calibrate the results. The model compared reasonably with observed discharges during calibration with a Correlation Coefficient (R²) of 0.73. However, in the initial model run, a Nash Sutcliffe Efficiency (NSE) of -0.02 was obtained. Uncertainties pertaining to the conceptual framework of the model and the high frequency of missing data gaps resulted in the poor model performance.

Keywords: Modelling, Watershed, Water balance, Black Volta Basin, SWAT and SUF2