Evaluation of satellite rainfall products to estimate extreme flow events over the Kulfo watershed in Ethiopia

Abstract

ABSTRACT Satellite rainfall products (SRPs) with high spatial and temporal resolutions offer opportunities to monitor extreme climate event intensities and trends on spatial different scales. A critical evaluation of the satellite precipitation dataset is very important for both the end users and data developers. Meanwhile, this evaluation may provide a benchmark for the product's continued development and future improvement. The main objective of this study is to evaluate the performance of globally gridded high-resolution SRPs (Tropical Rainfall Measuring Mission (TRMM), Climate Prediction Center Morphing (CMORPH), and CHRIPS) under sparse ground-based data and the complex topography of the Kulfo watershed through the semi-distributed hydrological model (SWAT). The model is calibrated for the period of 1991–2008 and validated for the period of 2009–2015. Comparisons of the simulations to the observed stream flow at the outlet of Kulfo watershed form the basis for the conclusions of this study. The Nash–Sutcliffe efficiency and the coefficient of determination were used to benchmark the model performance. The result indicated that all models underestimate the observed rainfall. The accuracy of models is not the same in representing the rainfall of the study area with TRMM performing the best (Bias = −5.78) and CMORPH performing the worst (Bias = −9.87). Overall, the SRPs tend to overestimate inter-annual rainfall variability.