Investigating the effectiveness of bias correction and merging MSWEP with gauged rainfall for the hydrological simulation of the upper Blue Nile basin

•The investigation is made between the simulated flow of gauge merged and unmerged MSWEP.•Tweaking the rainfall factor in the simulation of the unmerged MSWEP is carried out to improve the performance.•Results show that tweaking the rainfall factor gives better performance than the simulated flow of merged MSWEP product. Ethiopia, upper Blue Nile. This research mainly aims to investigate the effectiveness of merging and bias correction of Multi-Sources Weighted Ensemble Precipitation (MSWEP) using gauged rainfall and streamflow data for the hydrological modelling of the upper Blue Nile basin in which rainfall gauging stations are sparsely located. The comparison is made between the two simulated flows obtained from the merged MSWEP and bias-corrected of MSWEP global precipitation product. Fully distributed hydrological model of Coupled Routing and Excess STorage (CREST) is calibrated from 2000 to 2007 and validated from 2008 to 2012 for the upper Blue Nile river at the outlet of Abbay basin between the border of Ethiopia and Sudan. The result manifest that bias correction of MSWEP applying CREST model gives better performance than the simulated flow of merged MSWEP product. The Nash-Sutcliffe coefficient of efficiency (NSCE) and bias of the merged MSWEP are 0.81 and -33.2 %, respectively, as well the bias correction for the unmerged MSWEP shows 0.89 and -12 % of NSCE and bias performances for daily simulation. This suggests that to improve the predictive ability of streamflow rate, no demand to carry out merging MSWEP with sparsely located gauged rainfall, rather bias correction of MSWEP in the simulation of CREST improves the performance to capture the observed streamflow of the upper Blue Nile basin.