Application of Satellite Rainfall Products for the Assessment of Water Availability in Ethiopian Highlands: The Case of Ribb Watershed
Melese, Mulugeta Ferede
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One of the versatile use of satellite rainfall products is provision of continuous information which can be used for the assessment of water availability in the data sparse areas. Primarily, we compared the performance of TRMM 3B42 version 7 & CMORPH rainfall with Ribb rain gauge stations on the monthly timescale at the watershed scale. The TRMM 3B42 and CMORPH rainfall have shown similar strong PCC for both (0.99) and R2, 0.98 and 0.97, respectively compared to the rainfall Ribb stations. Both rainfall products are portrayed consistent underestimation evidenced by their bias results, 25.54% and 23.78%, respectively. The errors embedded in TRMM 3B42 V7 and CMORPH rainfall proved by their RMSE values 57.05 and 45.67, respectively. The RMSE% values of TRMM 3B42 V7 and CMORPH are found to be 47 and 37.75, respectively. The SUFI-2 algorithm in SWAT CUP was employed to quantify the parameter sensitivity and predictive uncertainty and we found 8 most sensitive parameters. Then, we obtained the acceptable p-factor and r-factor results, 0.85, 0.65, on calibration and 0.44, 0.28, on validation, respectively. Generally, the performance of SWAT model evaluation results on a monthly time step disclosed in the overall calibration and validation are very good in terms of NSE, R2 and PBIAS with calibration values 0.91,0.92 and 6.1 and validation values 0.85,0.85 and 5.8, respectively. Lastly, we appraised on the water availability of the Ribb watershed through simulated water balance components using both rainfall products. The simulated surface runoff contribution to total flow was found to be very high as compared to the lateral flow. The significant amount of water was lost through evapotranspiration. The overall results of this study can be used for hydro-climatological operations & researches, and could provide an insight to the sustainable water resources development and water management in Ribb and similar watersheds.