Assessment on Surface water potential in Data Scarce River Basin in Ethiopia: Case of Wabi-Shebele River Basin
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Date
2019-05
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Addis Ababa University
Abstract
Quantifying of the potential water resource is the most vital information for appropriate understanding and utilization for diversified economic activities and growth and transformation programs. However, it is hardly challenging, in data scares arid and semi-arid regions. Bias corrected re-analysis climate datasets, like Climate Forecast System Reanalysis (CFSR), became the alternative solutions to model or study the surface as well as the sub surface water resources since the last decade. This study intended to use the bias corrected Climate Forecast System Reanalysis (CFSR) dataset for the assessment of the surface water potential of one of the country data scares basin, Wabi-Shebele River Basin (WSRB). Linear scaling method was applied to avoid the bias on the globally reanalysis CFSR weather dataset to fit for the local conditions. The bias correction was done with limited observed rainfall data collected from National Meteorological Agency of Ethiopia (NMA) holding better records. And the performance of the bias correction evaluated statistically using NSE values ranges from 0.54 – 0.66, for different rainfall stations distributed over the basin. The bias corrected CFSR weather data, currently available local and global soils and land use data sets with better spatial resolution were used to develop the Soil and Water Assessment Tool (SWAT) hydrological model to evaluate the surfaces water potential of Wabi-Shebele River Basin. The statistical model performance evaluation at calibration and validation phase conformed that the model setup to mimic the reality in the ground and be a good tool to quantify the surface water potential of the basin. This model performance described with the statistical measures of NSE and coefficient of determination (R2) with values 0.40 and 0.44 on calibration and 0.11 and 0.12 on validation phase of the model development. Finally, the surface water potential of the basin estimated as 7.7 BCM, which is annually renewed with the normal hydrological conditions of the basin.
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CFSR, Reanalysis, SWAT, Surface Water Potential, Calibration, Validation