Application of satellite-derived rainfall for hydrological modelling in the data-scarce Black Volta trans-boundary basin

Abstract

This study, conducted in the Black Volta basin of Ghana, determined how well TRMM Multi-Satellite Precipitation Analysis (TMPA) data compare with rain gauge measurements. The potential of using the TMPA data as inputs into a hydrological model for runoff simulation in a data-scarce basin was also assessed. Using a point-to-grid approach, accumulations of ground measured rainfall on daily, monthly and annual time scales were compared with accumulations derived from TMPA daily rainfall grids. The TMPA derived data together with other free global data were used as input into the soil and water assessment tool (SWAT) to set up a hydrological model for the basin. This model was calibrated and validated using streamflow data from a station located downstream of the basin. The study results showed a correlation from 0.85 to 0.92 for the monthly accumulated rainfall. Also, good Nash-Sutcliffe efficiencies of 0.94 and 0.67 were obtained for calibration and validation, respectively, on monthly scale. Moreover, simulation of streamflow was 'satisfactory' to 'very good' in terms of trends and residual variation. The study, therefore, shows that the use of satellite rainfall in the basin would be of great benefit considering the difficulties in accessing data across the basin.