**2.3 Validation**

Station records from GRDC for the majority of the rivers in West Africa have missing values. Validation of PCR-GLOBWB for the selected river systems was limited to four gauging stations, where we could get a minimum of 5 hydrological years. Five performance evaluation metrics were used to evaluate discharge simulated at the selected gauging stations [44, 45]. These statistics are the Kling–Gupta efficiency (KGE); the Nash–Sutcliffe Efficiency criteria (NSE); the coefficient of determination (r2) per cent bias (PBIAS); and the ratio of RMSE-observations standard deviation (RSR). The performance ratings for quantitative statistics are presented in **Table 2**.
