Evaluation of Global Water Resources Data Products for Local Water Management Application in the Upper Blue Nile Basin in Ethiopia
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Date
2018
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Addis Ababa University
Abstract
Under the condition of water scarcity and competing water uses, improved knowledge of basin wide hydrology is pivotal for various water resources management and applications. Availability and quality of hydro-meteorological data sets determine understanding of the hydrology and sustainable planning and management of the basin resources. The quantity and quality of these data vary from region to region, and observations are sparse and irregularly distributed and declining in many countries particularly in Africa. To overcome these challenges and generate a consistent set of hydro-meteorological data products for global climatic and environmental understanding, alternative sources of data are emerging from different global research institutions. The increasing availability of global observation datasets, both from in-situ and remote sensors, along with advancements in earth system models and data assimilation algorithms, have led to the generation of a number of water resources reanalysis products that are available at global scale with high spatial and temporal resolutions. These global products hold great potential for water resource application at local scales in different parts of the world.
The aim of this study is to evaluate these global hydro-meteorological data products and improve the uncertainty for local use in local water resources application in upper Blue Nile basin, Ethiopia. The study has two components. The first component consists of evaluation different global precipitation products for runoff estimation at local level. The second component consists of evaluation of different global available runoff products for local water resources management application. In the first case, a fully distributed hydrological model Coupled Routing and Excess Storage (CREST) is used at different spatio-temporal scales. Two satellite and three reanalysis global gridded precipitation products with resolution of 0.5° and 0.25° are used.In the second case, Water Resources Reanalysis (WRR) river runoff products, WRR1 (seven products) available at 0.5° and WRR2 (four products) available at 0.25° are evaluated. Based on uncertainty analysis of these products, different dynamical bias correction schemes are implemented at each grid to improve the quality of the river runoff data for application at local scale.
Overall, the results show, the global precipitation and runoff products improve tremendously and can be used as alternative sources of data for various water resources applications with limited local fine tuning and bias correction. For the upper Blue Nile basin, the study indicates evaluation and adaptation of global reanalysis datasets is needed before application of the data for local water resources planning, design and management decisions. Using dynamical bias correction implemented at each grid (0.25o), this study develops 30 years (1980-2010) consistent set of daily streamflow data which can be used for various water management applications at local scale for both gauged and ungauged watersheds in the basin.
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Keywords
Global Water Resources, Upper Blue Nile Basin, Local Water Management, Evaluation