GIS-based hydrological zones and soil geo-database of Ethiopia

Land and water are vital resources to maintain the environment and livelihoods of mankind. Understanding the spatial variability of these resources has significant importance for planning, management, and utilization thereof. Despite their importance, there is no available, coherent, and systematically organized method for the characterization and mapping of the soil and hydrological systems in Ethiopia. A review-based research aimed at developing a geo-database of soils for hydrological studies and generation of the hydrological zones of the country based on the surface runoff potential is reported. In this analysis, data from 930 rainfall and 212 meteorological stations were used. Analysis based on a weighted overlay technique within ArcGIS using data from various sources and scales was conducted. A regression equation was used to develop the soil geo-database, scale factors of soil, land slope and climatic layers. An iterative analysis and expert knowledge was also used to determine the weights of the layers for the hydrological zoning. Results from this study provide valuable information about the hydrological zones of Ethiopia and an improved spatial soil database at 1:250,000 scale for the first time. Generated maps and zones will improve the hydrological understanding of the various regions of the country.

► We analyzed soils, topography and climatic data from over 1100 stations in Ethiopia.
► We setup a spatial model that uses rainfall, slope, evapotranspiration and runoff.
► We used spatial weighted overlay approach to generate hydrological zones of Ethiopia.
► The study improved the spatial soil database by a scale of four.