Water budget modelling of the Upper Blue Nile basin using the JGrass-NewAge model system and satellite data

Abstract

Abstract. The Upper Blue Nile basin is one of the most data-scarce regions in the world, hence, the hydrological information required for informed decision making in water resources management is limited. The hydrological complexity of the basin, tied with the lack of hydrometerological data, means that most hydrological studies in the region are either restricted to small subbasins where there are relatively better hydrometeorological data available, or at the whole basin scale but at very coarse time scales and spatial resolutions. In this study, we develop a methodology that can improve the state-of-art by using the available, but sparse, hydrometerological data and satellite products. To this scope, we use the JGrass-NewAGE system to estimates the water budget components (Precipitation J, Evapotranspiration ET, discharge Q, and storage ds/dt). The satellite products SM2R-CCI is used for obtaining the rainfall inputs; SAF EUMETSAT for cloud cover fraction for proper net radiation estimation; GLEAM for comparison with estimated ET; and GRACE gravimetry data also for comparison of the total water storage amounts available. Results are obtained at daily time-steps for the period 1994–2009 (16 years), and they can be used as a reference for any water resource development activities in the region. The overall long term mean budget analysis shows that precipitation of the basin is 1360 ± 230 mm per year. Evaporation covers 56 % of the yearly budget, runoff is 33 %. Storage varies from minus 9.7 % to plus 6.9 % of the budget.