‘Comparison and Evaluation of Satellite Rainfall products for Hydrological Modeling (case of Wabe watershed, Ethiopia

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Addis Ababa University


Satellite-based Rainfall products have been playing an immense role and used as an alternative source of data in regions where conventional rainfall measurements are not readily available or inadequate. The objective of this study is to evaluate and compare high-resolution satellite rainfall products such as CHIRPS, PERSIANN-CCS, RFE and TAMSAT with the ground-based observed rainfall data over the Omo-Gibe River Basin. For spatial assessment, a point to pixel approach at different temporal scale over the time window of 2003-2017 is used. Moreover, the capabilities, applicability, and limitations of satellite rainfall products were also evaluated by forcing the hydrological model (HBV-light) in Wabe Watershed from Omo-Gibe River Basin. Continuous statistics was used to assess their performance in estimating and reproducing rainfall amounts and categorical statistics was used to evaluate rain detection capabilities while Kling-Gupta Efficiency (KGE) is used for model performance evaluation. At mean daily scale, a good correlation agreement was observed by Wolkite with TAMSAT, RFE, PERSSIAN-CCS, CHRIPS (r=0.769, r=0.686, r=0.627, r=0.543) respectively. While the remaining station with the products show a low correlation and the time step has an important influence. This showed when the time step increases the accuracy of satellite rainfall products to predict the rainfall event relative to the station value will increase. The HBV model was simulated using datasets from 2003-2012 considering both satellite rainfall products and ground-based observed dataset. The model has shown good performance when calibrated with the gauged observed rainfall data. During calibration, the objective function showed KGE= 0.42 for daily, and KGE=0.61 for monthly time scale; whereas, the validation period showed KGE=0.54 and 0.71 for daily and monthly time scales respectively. The adjusted satellite rainfall estimates TAMSAT and RFE showed relatively good performance while adjusted PERSIANN-CCS and RFE relatively showed less performance. The adjusted TAMSAT data set perform the best result than that of the other dataset at daily and monthly time scale with KGE=0.39 and KGE=0.54 for calibration and KGE=0.6 KGE=0.72 for validation period respectively. Finally, this study reveals that besides the gauged observed rainfall data the bias-adjusted TAMSAT and RFE dataset can be used as an alternative dataset for hydrological modeling for the study area.