Suitability of global precipitation estimates for hydrologic prediction in the main watersheds of Upper Awash basin

Unavailability of optimum network of rain gauges and lack of well-organized precipitation data are one of the main challenges in hydrologic and climate-related studies. This study aims to evaluate the performance of three global precipitation data obtained from the Climate Forecast System Reanalysis (CFSR), Climate Prediction Center (CPC) and Tropical Rainfall Measuring Mission (TRMM) for hydrologic prediction at four main watersheds in the Upper Awash basin. Statistical indices and graphical efficiency measures were used to examine the CFSR-NCEP, CPC-NOAA, and TRMM data with the gauged data on mean annual, monthly, and daily basis at Upper Basin (UB) and Lower Basin (LB) area. The performance of global precipitation estimates was encouraging. Moreover, the spatial map of annual precipitation products demonstrated comparable spatial patterns with observed annual precipitation. The Soil and Water Assessment Tool (SWAT) model was used for hydrological simulation, and the hydrologic simulation efficiency of gauged data and global precipitation revealed good performance with R² and NS value of > 0.5 for daily, and > 0.7 for monthly scale simulations. However, lower to satisfactory model performance was obtained at the daily simulation in the Mojo and Akaki watersheds. The CPC-NOAA precipitation data was found superior in capturing the hydrologic variability. In relatively smaller watersheds, the suitability of global precipitation was lower due to the limited number of data points resulted from the coarse resolution of the data sources. Improvement in the satellite meteorology and climate reanalysis data could substantially increase the availability of alternative climate data for hydrologic studies.