Ethiopia’s Water Resources: An Assessment Based on Geospatial Data-Driven Distributed Hydrological Modeling Approach

Ethiopia is endowed with huge water potential but uneven distribution in rainfall, increasing demand, and recurrence of droughts have resulted in water scarcity in many parts of the country. The literature lacks spatial water resources assessment at a national scale, covering all the river basins. Large uncertainty in water resource potential is also reported in the literature. The present study utilizes the physics-based, semi-distributed Variable Infiltration Capacity (VIC) model to estimate the hydrological fluxes at national and river basin scales for the entire country of Ethiopia. The model is set up at a grid cell size of 0.05° × 0.05°, and hydrological simulation is carried out for a period spanning 16 years (1998–2013) at a daily time-step. As the model works on each grid cell independently, a geospatial data-driven approach is used for generating the model inputs, performing analysis, and presenting the outputs. The average annual runoff-depth for Ethiopia is estimated as 177 mm, while the average annual evapotranspiration and baseflow are estimated as 737 mm and 27 mm, respectively. Substantial variability in the spatial and temporal distribution of these hydrological fluxes is observed across the country. The runoff coefficient varies from 0.282 (Denakil river basin) to 0.037 (Ogaden river basin), with the country average being ~ 19%. While the spatial pattern of simulated annual runoff is as expected but modeled estimate (present study) is significantly higher than the existing national estimate. The present study underscores the advantage of the geospatial data-driven distributed hydrological modeling approach in assessing the water resource potential in a data-scarce country like Ethiopia. The results will be useful for sustainable development and management of water resources.